JPH06247169A - Drive device for vehicle - Google Patents

Abstract

(57) [Abstract] [Purpose] For a vehicle in which one of the left and right front wheels and the left and right rear wheels is driven by a motor, the use of the motor improves the turning performance of the vehicle during turning. . [Structure] The left and right front wheels 1FL and 1FR are driven by the engine 2 and the left and right rear wheels 1RL and 1RR are driven by hydraulic motors ML and MR, and a rear wheel target vehicle speed is given to the rear wheels 1R and 1FR.
The hydraulic motor M is set so that L and 1RR become the target vehicle speed.
For a vehicle in which L and MR are driven, when the vehicle turns, the target vehicle speeds given to the left and right rear wheels 1RL and 1RR are individually adjusted according to the vehicle speed to generate a yaw rate in the turning direction. As a result, steering using the motors ML and MR can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a vehicle in which a motor is used in addition to an engine to obtain rotational driving force for wheels, and more particularly, control of the drive device during turning of the vehicle. Regarding

[0002]

2. Description of the Related Art In recent vehicles, the number of four-wheel drive vehicles tends to increase. However, in a general four-wheel drive vehicle, for example, a vehicle in which an engine is arranged in the front part of the vehicle, the drive of the engine is A propeller shaft or the like for transmitting the force to the rear wheels is arranged below the floor panel, and it is necessary to bulge the floor panel toward the vehicle interior side in order to secure this accommodation space. There is a problem that it increases or the interior space of the vehicle is reduced.

In order to solve these problems, the left and right front wheels and the left and right rear wheels have heretofore been disclosed, for example, in Japanese Patent Laid-Open Nos. 57-74222 and 63-38031. It has been proposed to use one of them as a main drive wheel driven by an engine and the other as an auxiliary drive wheel driven by a motor. In the former publication, the distribution of the hydraulic pressure to the two hydraulic motors (hydraulic cylinders) on the left and right is automatically performed according to the road surface load applied to the left and right auxiliary drive wheels, and the function of the differential device is described. In the latter publication, two left and right electric motors are used, the generated voltage is increased as the vehicle speed increases, and the torque generated by the motor becomes constant.
A configuration is disclosed in which a manual switch can be used to switch between driving execution and driving stop by a motor.

[0004]

By the way, a vehicle equipped with a four-wheel steering device is generally known in order to improve the turning performance at the time of turning, but among the above-mentioned left and right front wheels and left and right rear wheels. If a vehicle in which either one of them is driven by a motor is provided with a conventional four-wheel steering system, not only the overall configuration of the vehicle becomes complicated, but also each control system is required, which makes the control complicated. There was a problem that it caused the change.

Therefore, the inventors of the present invention pay attention to a vehicle in which either the left front wheel or the right rear wheel is driven by a motor as described above, and improve this type of vehicle. Therefore, it was considered that the turning performance is improved without providing the conventional four-wheel steering device.

The present invention has been made in view of this point, and by using this motor for a vehicle in which one of the left and right front wheels and the left and right rear wheels is driven by the motor. An object of the present invention is to obtain a configuration capable of improving the turning performance when the vehicle turns.

[0007]

In order to achieve the above object, the present invention provides a yaw rate to a vehicle body by a driving force of a motor for driving one of the left and right front wheels and the left and right rear wheels when the vehicle turns. To improve the turning performance. Specifically, the invention according to claim 1 is, as shown in FIG. 1, left and right front wheels 1FL and 1FR and left and right rear wheels 1RL and 1RL.
One of the wheels 1FL and 1FR of 1RR is a main drive wheel that receives the driving force of the engine 2, and the other wheel 1R.
It is premised on a vehicle in which L and 1RR are auxiliary drive wheels that receive the driving force of the motors ML and MR. The motor drive force adjusting means U1 for adjusting the drive force of the motors ML and MR and the vehicle speed state recognizing means 91 for recognizing the vehicle speed state corresponding to the ground vehicle speed of the vehicle are provided. Then, the motor driving force adjusting means U1 is provided with the vehicle speed state recognizing means 91.
When the vehicle turns, the driving force of the motors ML and MR is controlled so that the rotational driving forces generated on the left and right auxiliary driving wheels 1RL and 1RR are individually adjusted according to the vehicle speed state. In addition, the yaw rate adjusting means 90 for generating the yaw rate in the turning direction is provided.

According to a second aspect of the present invention, the yaw rate adjusting means 90 is provided in the vehicle drive device according to the first aspect.
Of the left and right auxiliary drive wheels 1RL and 1RR, the motors ML and M are arranged to adjust the rotational driving force of only one auxiliary drive wheel.
The driving force of R is controlled to generate a yaw rate in the turning direction in the vehicle.

According to a third aspect of the present invention, in the vehicle drive device according to the first or second aspect, the yaw rate adjusting means 90 reduces the rotational driving force of the turning inner wheel when the vehicle speed state is a low vehicle speed state. The yaw rate in the turning direction is generated in the vehicle by controlling the driving force of the motors ML and MR.

According to a fourth aspect of the present invention, in the vehicle drive system according to the first or second aspect, the yaw rate adjusting means 90 increases the rotational driving force of the turning outer wheel when the vehicle speed state is a high vehicle speed state. The yaw rate in the turning direction is generated in the vehicle by controlling the driving force of the motors ML and MR.

According to a fifth aspect of the present invention, in the vehicle drive device according to the first aspect, a turning detection means 92 for detecting the turning of the vehicle is provided, and the yaw rate adjusting means 90 comprises:
In response to the detection signal of the turning detection means 92, the rotational driving force generated on the left and right auxiliary drive wheels 1RL and 1RR is individually adjusted according to the vehicle speed state when the vehicle turns, and a yaw rate in the turning direction is generated in the vehicle. It has such a configuration.

According to a sixth aspect of the present invention, in the vehicle drive device according to the first aspect, the vehicle speed state recognition means 91 is
The vehicle speed state of the vehicle is recognized based on the shift gear position, and the vehicle speed state recognizing means 91 recognizes that the vehicle speed state is the low vehicle speed state when the shift gear is in the low speed gear position, When the vehicle is in the high speed gear position, the vehicle speed state is recognized to be the high vehicle speed state.

According to a seventh aspect of the present invention, in the vehicle drive device according to the first aspect, friction coefficient detecting means 93 for detecting the friction coefficient of the road surface is provided. Then, the motor drive force adjusting means U1 is capable of changing the slip rate for restricting the rotational drive force of the auxiliary drive wheels 1RL, 1RR so that slip does not occur in the auxiliary drive wheels 1RL, 1RR. The slip ratio changing means 94 receives the output of the friction coefficient detecting means 93, and when the friction coefficient of the road surface is low, the slip ratios of the auxiliary drive wheels 1RL, 1RR are set to the slip ratios of the main drive wheels 1FL, 1RL. The value is set to a value different from.

According to an eighth aspect of the present invention, in the vehicle drive apparatus according to the first aspect, yaw rate detecting means S15 for detecting the yaw rate of the vehicle body is provided, and the yaw rate adjusting means 90 outputs the yaw rate detecting means S15. Therefore, when the yaw rate of the vehicle body exceeds the maximum value during turning, the driving force of the motors ML and MR is controlled so that the yaw rate generated in the vehicle during this turning becomes small.

[0015]

With the above construction, the present invention provides the following actions. In the invention according to claim 1, the main drive wheels 1FL, 1FR are rotated by the drive force of the engine 2, and the auxiliary drive wheels 1RL, 1RR are motors ML, M whose drive force is adjusted by the motor drive force adjusting means U1.
It is rotated by the driving force of R. When the vehicle turns, the yaw rate adjusting means 90 causes the vehicle speed state recognizing means 9 to operate.
1 signal, the left and right auxiliary drive wheels 1 depending on the vehicle speed
The driving forces of the motors ML and MR are controlled so that the rotational driving forces generated in the RL and 1RR are individually adjusted, whereby a yaw rate in the turning direction is generated in the vehicle, and the turning performance of the vehicle is achieved. Is improved.

According to the second aspect of the present invention, when the vehicle turns, the yaw rate adjusting means 90 causes the left and right auxiliary drive wheels 1R.
The yawing rate in the turning direction is generated in the vehicle by controlling the driving force of the motors ML and MR so that the rotational driving force of only one auxiliary driving wheel of L and 1RR is adjusted.

According to the third aspect of the present invention, when the vehicle speed state is a low vehicle speed state, the yaw rate adjusting means 90 controls the driving force of the motors ML and MR so as to reduce the rotational driving force of the turning inner wheel. This is an operation that actively generates this behavior by utilizing the fact that the behavior of the vehicle body is likely to occur greatly when the yaw rate is generated by braking to change the vehicle body posture. Therefore, the vehicle body posture is changed to improve the vehicle performance.

According to the fourth aspect of the present invention, when the vehicle speed state is the high vehicle speed state, the yaw rate adjusting means 90 controls the driving force of the motors ML and MR so as to increase the rotational driving force of the turning outer wheel. This is an operation for generating the required yaw rate while maintaining a stable high speed operation state without causing the above-described behavior during high speed operation.

In the fifth aspect of the invention, the yaw rate adjusting means 90 receives the detection signal of the turning detection means 92, and when the turning detection means 92 detects the turning of the vehicle, it causes the vehicle to generate a yaw rate in the turning direction. .

According to the sixth aspect of the invention, when the transmission gear is in the low speed gear position, the vehicle speed state recognizing means 91 recognizes that the vehicle speed state is the low vehicle speed state, and when the transmission gear is in the high speed gear position. The vehicle speed state recognizing means 91 recognizes that the vehicle speed state is a high vehicle speed state, and the yaw rate adjusting means 90 causes the vehicle to generate a yaw rate in the turning direction in accordance with the vehicle speed state.

According to the seventh aspect of the invention, the slip ratio changing means 94 receives the output of the friction coefficient detecting means 93, and when the friction coefficient of the road surface is low, the auxiliary drive wheels 1RL, 1RR.
Is set to a value different from the slip rates of the main drive wheels 1FL and 1RL. As a result, the posture of the vehicle body is adjusted by changing the gripping force of the front and rear wheels with respect to the road surface.

In the eighth aspect of the invention, the yaw rate adjusting means 90 receives the output of the yaw rate detecting means S15,
When the yaw rate of the vehicle body exceeds the maximum value during turning, the driving forces of the motors ML and MR are adjusted so that the yaw rate generated in the vehicle during this turning becomes small. As a result, the posture of the vehicle body in the latter half of the turn can be oriented in the escape direction of the curve, and the escape speed from the curve can be improved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the present invention will be described with reference to the drawings. Hereinafter, the procedure of the description will be described in the order of the configuration of the hydraulic system and the like, the description of each control mode, the description of the control system, and the description based on the flowchart of each control.

[Description of hydraulic system (FIG. 2)] In FIG. 2, 1FL is a left front wheel, 1FR is a right front wheel, 1RL is a left rear wheel, and 1RR is a right rear wheel. The engine 2 is arranged in front of the vehicle body, and the driving force of the engine 2, that is, the generated torque is
It is transmitted to the differential device 5 via the manual transmission 4 in which the clutch 3 and the forward gear are in the fifth gear and the reverse gear is in the first gear. And the differential device 5
From the above, the driving force of the engine 2 is transmitted to the left front wheel 1FL via the left drive shaft 6L, and the driving force of the engine 2 is transmitted to the right front wheel 1FR via the right drive shaft 6R. That is, the left front wheel 1FL and the right front wheel 1FR are the main drive wheels in the present invention.

Further, the left and right front wheels 1FL which become steering wheels,
The 1FRs are linked by a steering link 7 such as a tie rod, and the steering link 7 and the handle 8 are linked via a rack and pinion mechanism 9.

The left and right rear wheels 1RL, 1RR are the engine 2
Independently of, a pair of left and right hydraulic motors ML, MR
Is driven by. That is, the left rear wheel 1
The RL is driven by the left motor ML via the left drive shaft 11L, and the right rear wheel 1RR is driven by the right motor MR via the right drive shaft 11R. This left motor ML, that is, the left drive shaft 11L,
The right motor MR, that is, the right drive shaft 11R, is separated from each other and can be driven independently on the left and right sides. The left and right drive shafts 11L and 11R are
The hydraulic clutch 12 can be engaged and disengaged.
That is, the left rear wheel 1RL and the right rear wheel 1RR are the auxiliary drive wheels in the present invention.

The motor ML (MR) is of a turbine type (impeller type), has a first connection port La (Ra) and a second connection port Lb (Rb), and from La (Ra) to Lb ( Rb)
When the high-pressure oil liquid flows in, the rotation is in the forward direction, and when the high-pressure oil liquid flows in the opposite direction, the rotation is in the backward direction. The motors ML and MR have the same specifications, and the total value of the maximum generated torque is about 1/3 to 1/2 of the maximum generated torque of the engine 2.

In this embodiment, the rear wheel drive by the motors ML and MR is executed only under a predetermined condition described later. That is, the left and right front wheels 1F by the engine 2
Left and right rear wheels 1R even when L and 1FR are driven
L and 1RR may not be driven by the motors ML and MR.

P is a pump as a hydraulic pressure generation source, and this pump P is of a variable capacity type, and has an output shaft 2 of the engine 2.
It is driven by a via the drive pulley 13, the belt 14, and the driven pulley 15. The high-pressure oil liquid pumped up from the reservoir tank 16 by the pump P is discharged to the high-pressure line 18 to which the check valve 17 is connected. From the high-pressure line 18, the first and second hydraulic pressure supply lines 3 to which the check valves 10 or 32 are connected and which are parallel to each other are provided.
1A and 31B have been derived. Further, a release line 23 is led out from the reservoir tank 16. Furthermore, the connection ports La and Lb (Ra, of the motor ML (MR) are
From Rb), lines 20L, 21L, which are parallel to each other,
(20R, 21R) has been derived.

The lines 20L and 21L of the left motor ML are the switching valve VVA, the lines 19 and 19L and the lines 22 and 22L which are parallel to each other, and the switching valves VVB.L and VVE.
L can be used to selectively connect to the first hydraulic pressure supply line 31A and the release line 23. Similarly,
The lines 20R and 21R of the right motor MR connect the switching valve VV.
A, lines 19 and 19R and lines 22 and 2 parallel to each other
2R and switching valves VVB ・ R, VVE ・ R
The first hydraulic pressure supply line 31A and the release line 23 can be selectively connected.

A switching valve VVI is connected to the second hydraulic pressure supply line 31B downstream of the check valve 32, and a flow dividing valve 34 is connected further downstream thereof. Shunt valve 3
One branch supply line 33L branched into two by 4
Is connected to the line 19L, and the other branch supply line 33R is connected to the line 19R.

An accumulator 41 for storing a high pressure oil pressure is connected to the high pressure line 18. For this high-pressure line 18, line 20L (20R)
Are connected by a passage 42L (42R). In this passage 42L (42R), a check valve 43L (43
R) and the switching valve VVF · L (VVF · R) are connected. The passages 42L and 42R are parallel to each other, and each of the valves VVA, VVB · L (VVB · R), VVE · L (V
VE / R), VVI, the shunt valve 34, etc. are bypassed.

The line 20L (20R) and the line 21
The L (21R) is communicated with the communication passage 51L (51R), and the variable orifice VVC · L (VVC · R) is connected to the communication and 51L (51R).

Further, an actuator for connecting and disconnecting the clutch 12 is indicated by reference numeral 61. The supply line 62 for the actuator 61 can be selectively connected to the high pressure line 18 and the discharge line 63 can be selectively connected to the release line 23 by using the switching valve VVJ. Both lines 62 and 63 can be in a state of being cut off.

The left and right motors ML and MR are connected to each other by a communication passage 71, and the opening / closing valve V is connected to the communication passage 71.
VD is connected.

The release line 23 is connected to the high-pressure line 18 on the upstream side (pump P side) of the check valve 17 via a load / unload valve VVH and on the downstream side of the check valve 17. At safety valve V
It is connected via VG.

[Explanation of Control Modes (Table 1)] In this embodiment, there are a total of eight control modes as will be described later, and the operating states of the above-mentioned valves when each mode is executed are summarized. Are shown in Table 1 below. In Table 1, the symbols "L" and "R" for identifying the left and right are omitted. In addition, load / unload valve V not shown in Table 1
The VH is controlled to open and close so that the pressure in the high pressure line 18 falls within a predetermined pressure range between the lower limit value and the upper current value.

[0038]

[Table 1]

In the respective control modes shown in Table 1, the operating states of the valves which perform the main functions will be specifically described.
It is as follows.

(1) Integrated Mode As will be described later in detail, the integrated mode controls the drive of the motors ML and MR so that the left and right rear wheels 1RL and 1RR have the same rotational speed. There are two types, auxiliary and reverse drive (braking). In this integrated mode, the clutch 12 is engaged (the switching valve VVJ is connected to the line 6).
2 open and line 63 closed), switching valve VVB ・ L
(VVB / R), VVE / L (VVE / R) and VV
The operation mode of I is the state shown in FIG. In this state,
The switching valve VVA is controlled to switch the hydraulic pressure supply direction according to the forward drive or the reverse drive (forward / reverse direction setting of the motors ML and MR) and the supply flow rate to the motors ML and MR (first). (1) Hydraulic pressure supply using the supply line 31A). It should be noted that in reverse driving, a larger deceleration force is obtained than in a hydraulic lock mode, which will be described later, but of course, when the vehicle is moving forward, the rear wheels 1RL, 1RR
Does not give a large driving force to rotate in the direction opposite to the traveling direction of the vehicle, but gives a braking force to the rear wheels 1RL, 1RR.

(2) Independent Mode In the independent mode, as will be described in detail later, the drive control of the motors ML and MR is performed so that the left and right rear wheels 1RL and 1RR respectively have the target wheel speeds independently set. As in the case of the integrated mode described above, there are two types, that is, forward drive and reverse drive. Also, in this independent mode,
The clutch 12 is released (the switching valve VVJ closes the line 62 and opens the line 63). Switching valve VVE
The operating mode of L (VVE · R) is set to the state shown in FIG. 2, but the switching valve VVA is set to the central switching position and the first hydraulic pressure supply line 31A is shut off. The switching valve VVI is in the open position, and is in the hydraulic pressure supply mode using the second hydraulic pressure supply line 31B. In this state, the switching valve VVB ・ L (VVB ・ L
R) is controlled to switch the hydraulic pressure supply direction according to the forward drive or the reverse drive (setting of the forward and reverse directions of the motors ML and MR) and the supply flow rate to the motors ML and MR.

(3) LSD mode The LSD mode obtains an operation limiting function and is a switching valve V
VB • L and VVB • R are lines 20L and 21L (2
0R, 21R) are both closed to completely cut off the supply and discharge of hydraulic pressure to the motors ML and MR. And
It is prevented that the opening / closing valve VVD is opened to communicate the closed left and right hydraulic paths of the two motors ML and MR with each other to cause a large rotation difference between the left and right motors ML and MR. To do. In this LSD mode, the variable orifice VVC.L (VVC.R) is fully closed.

(4) Hydraulic lock mode The hydraulic lock mode uses the passage resistance, that is, the variable orifice V.
The deceleration force is obtained by using the throttle resistance of VC · L (VVC · R). In this hydraulic lock mode, the switching valve V
The VB / L and VVB / R are in the central switching position, the lines 20L, 21L, 20R and 21R are shut off, and the open / close valve VVD is closed. And the variable orifice V
VC / L and VVC / R are opened. In this state, the oil liquid circulates in the closed hydraulic circuit formed including the variable orifices VVC · L (VVC · R) in response to the rotation of the motor ML (MR). Variable orifice VVC ・ L (VVC ・ R) that allows oil to pass through during circulation
The throttle resistance of (2) gives a deceleration force to the vehicle. Then, the opening amounts of the variable orifices VVC · L and VVC · R are controlled so as to become smaller as the vehicle deceleration increases (variable orifices VVC · L, V depending on the deceleration).
The setting of the VC / R opening is illustrated in step E37 of FIG. 5). The clutch 12 may be either in the engaged state or the disengaged state.

(5) Accumulation mode In the accumulation mode, the vehicle, that is, the rear wheels 1RL, 1RR is in motion.
The motors ML and MR driven by the pump function as pumps to cause the accumulator 41 to accumulate pressure. In this pressure accumulation mode, the line 21L (21R) is communicated with the reservoir tank 16, while the on-off valve VVF · L
(VVF · R) is opened, and the oil liquid is pumped up into the reservoir tank 16 by the motor ML (MR) and accumulated in the accumulator 41.

(6) Stopping mode In the stopping mode, the motors ML and MR are used to stop the vehicle when the parking brake is not operating.
Drive control. (The drive of the motors ML and MR is controlled so that the vehicle speed becomes the target vehicle speed 0). In this case, the second hydraulic pressure supply line 31B is used as the hydraulic pressure supply line, and the hydraulic pressure supply / discharge control is performed by the switching valve VVB · L (VVB
・ R) is used.

(7) Parking Mode The parking mode enhances the action of maintaining the parking state when the parking brake is operated. That is, in the parking mode, the switching valve VVB · L
(VVB · R) is set to the closed position of the central switching position to disconnect the hydraulic pressure supply / discharge line, and the clutch 12 is engaged.

(8) F / S mode The F / S mode is a fail-safe mode, and when there is some abnormality, for example, when the high voltage line 18 becomes abnormally high, the motors ML and MR are normally operated. When it is no longer driven, when a certain valve is stuck, or when the oil temperature rises above a certain temperature,
The safety valve VVG is opened and the hydraulic pressure in the high pressure line 18 is released.

[Explanation of Control System (FIG. 3)] FIG. 3 shows a control system according to the present invention. U1 and U in the figure
Reference numerals 2 and U3 are control units each configured by using a microcomputer, and the control unit U1 is a main control unit that controls the above-described valves VVA and the like. That is, the main control unit U1 serves as the motor driving force adjusting means in the present invention. The control unit U2 is for ABS control (antilock brake control), and the control unit U3 is for traction control. Further, S1 to S15 are sensors or switches, respectively.

The sensors S1 to S4 are used for the wheels 1FL to 1R, respectively.
The rotation speed of R, that is, the wheel speed is independently detected, and the wheel speed detected by each of the sensors S1 to S4 is transmitted from the control unit U2 to the control units U1 and U3. The sensor S5 detects the vehicle speed, and in the present embodiment, detects the vehicle speed to ground (absolute vehicle speed detection). The sensor S6 detects the shift position of the transmission 4, that is, the gear position. The sensor S7 detects the engine speed. The sensor S8 detects the steering angle of the steering wheel. The sensor S9 detects the accelerator opening. The sensor S10 detects the amount of depression of the brake pedal. The switch S11 is an ignition switch. The switch S12 is for detecting whether or not the parking brake is operated. The sensor S15 is a yaw rate sensor as the yaw rate detecting means in the invention described in claim 8, and detects the angular velocity around the vertical axis of the vehicle body.

The switch S13 is a manual switch, and is "AUTO", "integrated control", "independent control", "O".
Four control modes of "FF" are selected. The sensor S14 detects a bad road (uneven road). In this rough road detection, for example, the sensor S14 detects the vertical stroke of the suspension, and the main control unit U1 determines that the rough road is when a stroke of a predetermined amount or more occurs a predetermined number of times within a predetermined time. Further, the main control unit U1 determines that the sensor S14 detects up and down G (acceleration) acting on the vehicle body and that when the up and down G above a predetermined number occurs a predetermined number of times or more within a predetermined time, it is a bad road. It can also be configured to. The degree of bad road may be determined by changing one or more of the threshold values for the bad road determination.

The signals from the sensors or switches S5 to S15 are input to the main control unit U1, and the main control unit U1 controls the above-mentioned valves VVA to VVJ. Of course, the control unit U2 is for preventing the wheels from locking during braking,
From 2 onward, the brake fluid pressure adjusting means 81 for individually adjusting the brake of each wheel is controlled. Further, the control unit U3 reduces at least the engine output (torque generated by the engine 2) when the left and right front wheels 1FL and 1FR, which are constantly driving wheels, slip excessively on the road surface during acceleration or the like. The torque adjusting means 82 for adjusting the opening of the throttle valve of the engine 2, the ignition timing, the fuel injection amount, etc. is controlled.

From the control unit U2 to the main control unit U1, in addition to the wheel speed signals detected by the sensors S1 to S4, an ABS signal indicating that ABS control is being executed and a μ signal indicating the road surface μ (friction coefficient). Is transmitted. Further, a wheel speed signal is transmitted from the control unit U2 to the control unit U3. Further, from the control unit U3 to the main control unit U1, a TRC signal indicating that the traction control is being executed, a torque reduction amount signal indicating a reduction amount of the engine torque performed by the traction control, and a road surface μ signal are transmitted. It The road surface μ may be detected by the main control unit U1, and the wheel speeds detected by the sensors S1 to S4 may be directly input to the main control unit U1.

[Description of Main Flowchart (FIG. 4)]
Next, the control content of the main control unit U1 will be described with reference to the flowcharts in FIG. In the following description, D, E, W and Z indicate steps, respectively.

First, the main flow chart of FIG. 4 will be described. In this main flow chart, first, after signals from the respective sensors are input at DO, the ignition switch S11 is turned on at D1.
It is determined whether or not it is in the FF state. The ignition switch S11 is not in the OFF state according to the determination of D1 NO
If it is, the ignition switch S1 is set at D2.
It is determined whether or not 1 is in the ON state, and the determination of D2 indicates that the ignition switch S11 is not in the ON state.
At this time, at D3, the safety valve VVG is opened, and the pressure in the high-pressure line 18 is released. Also,
The ignition switch S11 is turned on by the determination of D2.
If YES in the state, at D4, the safety valve VV
G is closed, and a high pressure hydraulic pressure is supplied to the high pressure line 18. Then, at D5, the vehicle speed sensor S
It is determined whether or not the vehicle speed (ground vehicle speed) detected by 5 is approximately 0, and the vehicle speed is approximately 0 in this determination of D5 Y
When ES, at D6, the gear position detection sensor S6
Is detected, it is determined whether the gear position of the transmission 4 is neutral. If YES in step D6, that is, if the gear position of the transmission 4 is in neutral, in step D7 it is determined whether or not the parking brake is activated by detection of the parking brake detection switch S12. In step D7, parking is performed. If YES, that is, if the brakes are operated, the above-described parking mode control is executed in D8 so that the performance of maintaining the parking state of the vehicle is enhanced. If the parking brake is not operated in the determination of D7, NO
At 9, the vehicle stop mode control as described above is executed so that the vehicle speed becomes zero. On the other hand, when the vehicle speed is not substantially 0 in the determination of D5, that is, when the vehicle is traveling, or in the determination of D6, the transmission 4
When the gear position of is NO, which is not neutral, D10
At, it is determined whether the gear position of the transmission 4 is the reverse position. If the determination at D10 is NO, that is, the gear position of the transmission 4 is not the reverse position, then at D11, it is determined whether or not the vehicle is currently stuck. Whether or not the vehicle is in this stack is determined by, for example, detecting that the accelerator opening detection sensor S9 is operating the accelerator pedal,
When the vehicle speed is substantially zero and the rotation speeds of the left and right front wheels 1FL, 1FR detected by the wheel speed sensors S1 to S4 are sufficiently higher than the vehicle speed, it can be determined that the vehicle is in a stack. If the determination in D11 is NO, that is, if the vehicle is not in the stack, it is determined in D12 whether or not the control conditions for performing other control modes other than the parking mode and the stop mode, which will be described later, are satisfied. At D13, as will be described later, the execution of the control mode is determined, and the control is executed / not executed. Also, the D10
If the determination result is YES and the gear position of the transmission 4 is in the reverse position, the drive using the motors ML and MR is executed in D15, but in this case, the reverse drive is performed in the independent mode ( Drive the rear wheels 1RL, 1RR in the backward direction). If YES in the determination of D11 that the vehicle is in the stack, drive assistance using the motors ML and MR is executed in D14. In this case, the target vehicle speed is set to a low vehicle speed (for example, 10 km that is a stack release condition). / H)) and the positive drive is performed in the independent mode described later.
Further, the ignition switch is turned off by the determination of D1.
In the case of YES in the F state, after the clutch 12 is engaged in D16, the clutch engagement is maintained in D17 (the switching valve VVJ closes both the lines 62 and 63), and then in D18, the safety valve VVG. Is opened.

[Description of Mode Determination Flowchart (FIG. 5
(FIG. 8)] Next, the details of the determination operation as to whether or not the control condition for performing the control mode of D12 in the main flow chart (FIG. 4) described above is satisfied will be described based on the mode determination flow charts of FIGS. explain. This mode determination flowchart is based on the premise that it is not a good road, that is, a bad road. First, at E24 in FIG.
It is determined whether or not the traction control is currently being performed by the control unit U3. If NO in traction control based on the determination at E24, it is determined at E25 whether the road surface is low μ. If NO at step E25, the road surface is not low μ. It is determined whether or not it is in the middle. In the present embodiment, whether or not the vehicle is going straight is determined by calculating the lateral G based on the steering wheel steering angle detected by the steering wheel steering angle sensor S8 and the vehicle speed detected by the vehicle speed sensor S5. When it is less than a predetermined value, it is determined that the vehicle is traveling straight ahead. If YES in the determination of E26, the processing of E27 to E39 is performed, but this processing is based on the premise that the road is a good road, a high μ road, and the vehicle is in a straight line. It is determined whether or not the control conditions for performing the forward drive (E28) and the reverse drive (E35) in the integrated mode, the pressure accumulation mode (E33, E39) or the hydraulic lock mode (E31, E37) are satisfied. Specifically, E27
At E28, it is determined whether or not the vehicle is in the rapid acceleration operation state, and when the determination at E27 is YES that is the sudden acceleration operation state, it is determined at E28 that the condition for the positive drive in the integrated mode is satisfied. In other words, the driving force is assisted by driving the rear wheels 1RL and 1RR in the forward direction when the vehicle runs straight on a high μ road and is suddenly accelerated. Further, when the determination in E27 is NO, that is, when the vehicle is not in the rapid acceleration operation state, E
At 29, it is determined whether or not the vehicle is in the high speed operation state.
When the determination in E29 is NO, which is not the high speed operation state, it is determined in E30 whether the vehicle is in the slow deceleration operation state, and in the determination in E30, the vehicle is in the slow deceleration operation state YES.
When it is, it is determined at E31 that the hydraulic lock mode condition is satisfied. In other words, the rear wheels 1RL and 1R are operated when traveling straight on a high μ road and during slow deceleration in the medium-low speed operation state.
The deceleration force is slightly increased by giving a resistance to the rotation of R. On the other hand, if NO in the slow deceleration operation state in the determination of E30, it is determined in E32 whether the rapid deceleration operation state is in effect. If the determination in E32 is YES in the rapid deceleration operation state, the pressure accumulation mode condition is determined in E33. Is determined to have been established. That is,
At the time of going straight on a high μ road and at the time of sudden deceleration in a medium-low speed operation state, resistance is applied to the rotation of the rear wheels 1RL, 1RR, while the rotation of the rear wheels 1RL, 1RR is used to accumulate pressure in the accumulator 41. ing. Further, if the determination in E29 is YES, which is the high-speed operation state, it is determined in E34 whether or not the rapid deceleration operation state is established, and this E3
When it is YES in the sudden deceleration operation in the determination of 4, E3
In 5, it is determined that the condition for reverse driving in the integrated mode is satisfied. That is, the deceleration force is increased by applying a large braking force to the rotation of the rear wheels 1RL and 1RR when the vehicle runs straight on a high μ road and is rapidly decelerated in a high speed operation state. On the other hand, if the determination in E34 is NO, which is not the rapid deceleration operation state, it is determined in E36 whether the vehicle is in the slow deceleration operation state. If the determination in E36 is YES in the slow deceleration operation state, the hydraulic lock mode is set in E37. It is judged that the condition is satisfied, and the opening of the variable orifice VVC is set according to the deceleration. That is, when the vehicle runs straight on a high μ road and is slowly decelerated in a high speed operation state, a resistance corresponding to the deceleration is applied to the rotation of the rear wheels 1RL, 1RR to slightly increase the deceleration force. If NO in the slow deceleration operation state in the determination of E36, it is determined in E38 whether it is the steady operation state. If the determination in E38 is YES in the steady operation state, the pressure accumulation mode condition is set in E39. Is determined to have been established. In other words, the rear wheels 1RL and 1RR are traveling straight on a high μ road and in a steady state in a high-speed driving state.
The pressure is stored in the accumulator 41 by utilizing the rotation of. When the determination in E32 and E38 is NO, the operation mode is not established and the process ends.
In other words, the rear wheels 1RL,
The RR is not driven. The degree of acceleration and the degree of deceleration as described above can be made by various known methods. For example, the degree of acceleration can be known by any one or a plurality of combinations of the accelerator pedal depression speed, the accelerator pedal depression amount, the vehicle body acceleration obtained by differentiating the vehicle speed, and the like. The degree of deceleration is, for example, the magnitude of the accelerator release speed, the magnitude of the brake depression speed, the increase amount of the brake depression amount,
It can be known from any one of the vehicle body decelerations obtained by differentiating the vehicle speed or any combination thereof.

If NO in the straight running state as determined by the determination of E26 (FIG. 5), the process of FIG. 6 is executed, but this FIG. 6 is premised on a good road, a high μ road and turning. Will be things. And finally, the forward drive (E42) and the reverse drive (E44) in the independent mode or the LSD mode (E42).
It is determined whether or not the control condition for performing 45) is satisfied. Specifically, in E41, it is determined whether or not the vehicle is in the rapid acceleration operation state. When the determination in E41 is YES, that is, the rapid acceleration operation state, it is determined in E42 that the condition for the positive drive in the independent mode is satisfied. To be done. That is, high μ
At the time of sudden acceleration accompanied by turning on the road, the rear wheels 1RL and 1RR are independently driven to rotate normally to assist the turning driving force. When the determination in E41 is NO, which is not the rapid acceleration operation state, it is determined in E43 whether the deceleration operation state is in effect. If YES in the deceleration operation state in the determination in E43, it is determined in E44 that the reverse driving condition in the independent mode is satisfied. In other words, the rear wheels 1RL, 1R during deceleration accompanied by turning on a high μ road
The deceleration force is increased by applying a large independent braking force to each R. On the other hand, when the determination in E43 is NO, that is, when the vehicle is not in the deceleration operation state, L is set in E45.
It is determined that the SD mode condition is satisfied. That is, when turning without acceleration / deceleration on a high μ road, the left and right rear wheels 1RL, 1
Smooth turning is performed while suppressing the occurrence of a large rotation difference in RR.

Further, if the determination in E25 (FIG. 5) is YES, that is, the road surface is low μ, the processing shown in FIG. 7 is performed. In FIG. 7, first, at E51, it is judged if the vehicle is traveling straight ahead. If YES in the determination of E51 when the vehicle is traveling straight, the processing of E52 to E59 is performed, but this is processing on the condition that the vehicle is a good road, a low μ road, and traveling straight. And finally, the forward drive (E55) and the reverse drive (E57) in the independent mode, and the hydraulic lock mode (E
54), it is determined whether the control condition for performing the LSD mode (E59) is satisfied. Specifically, at E52, it is determined whether or not the vehicle is in the high speed operation state. If the determination at E52 is YES, that is, the high speed operation state, then at E53, it is determined whether or not the vehicle is in the deceleration operation state.
If YES in the deceleration operation state according to the determination of 3, E54
At, it is determined that the condition of the hydraulic lock mode is satisfied. That is, the deceleration force is slightly increased by imparting resistance to the rotation of the rear wheels 1RL and 1RR when the vehicle runs straight on a low μ road and decelerates from a high speed operation state. If the determination in E53 is NO, which is not the deceleration operation state, it is determined in E55 that the condition for the positive drive in the independent mode is satisfied. That is, the driving force is assisted by independently driving the rear wheels 1RL and 1RR in the forward direction during straight traveling on a low μ road and at high speed operation. On the other hand, when the determination in E52 is NO, which is not the high speed operation state, it is determined in E56 whether or not it is in the rapid acceleration operation state, and in this E56 determination, the rapid acceleration operation state is YE.
When S, it is determined in E57 that the condition for the positive drive in the independent mode is satisfied. That is, the driving force is assisted by independently driving the rear wheels 1RL and 1RR in the forward direction even when the vehicle runs straight on a low μ road and is suddenly accelerated from a stopped state or a medium-low speed operation state. Also, the E5
When it is NO in the sudden acceleration operation state according to the determination of 6, E58
It is determined whether or not the vehicle is in the deceleration operation state at
If it is NO in the deceleration operation state in the determination of 58, E5
At 9, it is determined that the LSD mode condition is satisfied. That is, stable traveling is performed while suppressing the occurrence of a large rotation difference between the left and right rear wheels 1RL and 1RR during straight traveling without acceleration / deceleration on a low μ road. The above E
When the result of the determination at 58 is YES, the operation mode is not established and the process ends.

If NO in the straight running state in the determination of E51 (FIG. 7), the process shown in FIG. 8 is executed, but this process is premised on a good road, a low μ road and at the time of turning. It becomes the processing that was done. And finally, the positive drive (E62) in the independent mode, the hydraulic lock mode (E65), the LSD
It is determined whether the control condition for performing the mode (E66) is satisfied. Specifically, it is determined in E61 whether or not the vehicle is in the rapid acceleration operation state. If the determination in E61 is YES, that is, the rapid acceleration operation state, it is determined in E62 that the condition for the positive drive in the independent mode is satisfied. To be done. In other words, the rear wheels 1RL, 1R during sudden acceleration accompanied by turning on a low μ road
The rotation driving force is assisted by independently driving R to rotate normally. On the other hand, when the determination in E61 is NO, which is not the rapid acceleration operation state, it is determined in E63 whether the vehicle is in the high speed operation state. When the determination in E63 is YES, which is the high speed operation state, the deceleration operation state is in E64. It is determined whether or not there is this E6
If YES in the deceleration operation state in the determination of 4, it is determined that the condition of the hydraulic lock mode is satisfied. That is, the rear wheel 1R is decelerated during deceleration from high speed operation involving turning on a low μ road.
The deceleration force is slightly increased by giving a resistance to the rotation of L and 1RR. If NO in the deceleration operation state in the determination of E64 or NO in the high speed operation state in the determination of E63, L is set in E66.
It is determined that the SD mode condition is satisfied. That is, during high-speed operation accompanied by turning without acceleration / deceleration on a low μ road or during medium-low speed operation, smooth turning is performed while suppressing the occurrence of a large rotation difference between the left and right rear wheels 1RL, 1RR.

[Explanation of Execution Judgment Flowchart (FIG. 9)] Next, the control content of D13 in the above-mentioned main flow chart (FIG. 4) will be described with reference to FIG. The process of FIG. 9 is for finally executing and not executing the mode satisfying the control conditions of FIGS. 5 to 8 described above. First, in W0, it is determined whether or not the control conditions for performing the control modes other than the integrated mode and the independent mode are satisfied. If YES in the determination of W0 that the control condition for performing the control mode other than the integrated mode and the independent mode is satisfied, the control mode satisfying the control condition is executed in W4 (LSD mode, hydraulic lock mode, pressure accumulation mode). Mode execution). When the determination condition of W0 is NO and the control condition for performing the control mode of the integrated mode or the independent mode is satisfied, in W1, the operation state (selected state) of the manual switch S13 is “OFF”.
Is determined. With this determination of W1, the operation state of the manual switch S13 is “OFF” YES
In this case, it is assumed that the driver does not want the drive assist using the motors ML and MR, and the drive assist using the motors ML and MR is prohibited (not executed) in W2. On the other hand, when the operation state of the manual switch S13 is not “OFF” in the determination of W1, the operation state of the manual switch S13 is “AUT” in W3.
It is determined whether or not it is "O". If the operation state of the manual switch S13 is "AUTO" in the determination of W3, that is, if YES, then in W4, the control mode satisfying the control conditions is executed including the driving assistance by the motors ML and MR. Further, when the operation state of the manual switch S13 is NO, which is not "AUTO" in the determination of W3, it is determined in W5 whether or not the control condition in the integrated mode is satisfied. When the determination condition of W5 is YES and the control condition in the integrated mode is satisfied, W
In 6, it is determined whether or not the operation state of the manual switch S13 is the "integrated mode" selection. This W
If the operation state of the manual switch S13 is YES in the "integrated mode" selection in the determination of 6, then in W7,
It is determined whether or not the road is a bad road, and if NO in the determination of W7, that is, the road is a bad road, the motors ML and MR are driven in the integrated mode in W8. When the operation state of the manual switch S13 is NO in the determination of W6 and the "integrated mode" is not selected, or when the determination of W7 is YES which is a bad road, the motors ML and MR are driven in the independent mode in W9. To be executed. On the other hand, when the determination of W5 is NO, that is, when the control condition in the integrated mode is not satisfied, the processing of W10 to W15 is performed, but this processing corresponds to the processing of W6 to W9 described above. ing. That is, in W10, it is determined whether or not the control condition in the independent mode is satisfied, and in this determination in W10, the control condition in the independent mode is satisfied. If YES, then in W11, the manual switch S13 is pressed. It is determined whether or not the operation state is the selection of “independent mode”. Manual switch S depending on W11
When the operation state of 13 is YES in the selection of the "independent mode", the motor ML in the independent mode in W13,
Driving assistance by MR is executed. In addition, if the operation state of the manual switch S13 is NO in the selection of "independent mode" in the determination of W11, it is determined whether or not the road is a bad road in W12. , W14, it is determined whether or not the vehicle is turning, and if the determination in W14 is NO, that is, the vehicle is not turning, then in W15, the motor ML in the integrated mode,
Driving assistance by MR is executed. In addition, when the determination condition of W10 is NO and the control condition in the independent mode is not satisfied, and when the determination of W12 is YES, which is a bad road, or W14
If it is YES at the time of turning according to the determination, the drive assistance by the motors ML and MR is prohibited in W2.

[Explanation of Independent Mode Positive Drive Flowchart (FIGS. 10 and 11)] FIGS. 10 and 11 show the details of the positive drive control in the independent mode. The normal drive control in the integrated mode is substantially the same as the normal drive control in the independent mode, except that the same target vehicle speed is applied to the left and right rear wheels. First, after signals such as the ground vehicle speed VA and the wheel speed VB are input in Z1, the target vehicle speed VTR is set in Z2 using the accelerator opening and the shift position of the transmission 4 as parameters. Then Z
At 3, it is determined whether or not the value obtained by subtracting the actual wheel speed VBL of the left rear wheel 1RL from the target vehicle speed VTR is equal to or higher than the predetermined speed V1. If the determination of Z3 is NO, it is determined that the drive assistance by the positive drive is not necessary, and the normal drive of the left rear wheel is stopped at Z14. The processes of Z3 and Z14 are performed independently for the right rear wheel 1RR and separately for the left rear wheel 1RL. The predetermined speed V1 is set to a speed indicating a slip amount sufficient for acceleration, but it may be set to a constant value, or may be set to a variable value so that the vehicle speed VA increases as the vehicle speed VA increases. Z3
If the determination is YES, it is determined whether or not the accelerator is fully closed in Z4. Even if the determination in Z4 is YES, it is determined that the drive assistance using the motors ML and MR is not necessary and Z14 is performed. (In this case, the right and left rear wheels 1RL, 1RR are simultaneously stopped for normal driving). When the determination in Z4 is NO, in Z5, the lateral G acting on the vehicle body is calculated based on the vehicle speed VA and the steering wheel steering angle. Thereafter, in Z6, the correction coefficient k1 based on the lateral G,
k2 is set. That is, here, the correction coefficient for correcting the target wheel speeds of the outer turning wheel and the inner turning wheel that cause a difference in rotation at the time of turning is obtained. The correction coefficients k1 and k2 are coefficients for giving the target wheel speeds of the left and right rear wheels 1RL and 1RR in order to obtain a neutral steered traveling state (a traveling state in which neither an understeer state nor an oversteer state occurs) in the vehicle. . Then, Z7 (Fig. 1
In 1), it is determined whether or not the vehicle is making a right turn. If YES in the determination of Z7, in Z9, the left rear wheel 1
The target wheel speed VTRL of the RL is a correction coefficient k1 and a correction coefficient k described later with respect to the target vehicle speed VTR determined in Z2.
Calculated by multiplying by 1A, similarly, the right rear wheel 1
The target wheel speed VTRR of the RR is calculated by multiplying the target vehicle speed VTR by a correction coefficient k2 and a correction coefficient k2A described later. If NO in Z7, Z8
At, the respective target wheel speeds of the left and right rear wheels 1RL, 1RR are calculated. After all, the processing of Z6 to Z9 corresponds to the processing of increasing the target wheel speed on the turning outer wheel side and decreasing the target wheel speed on the turning inner wheel side, and as a feature of this example, the correction coefficients k1A and k2A are used to adjust the left and right rear wheels 1RL. The target vehicle speed of 1RR is corrected so that the vehicle shifts from the neutral steer running state to the over steer running state, that is,
A yaw rate in the turning direction is generated in the vehicle to improve the turning performance of the vehicle (this correction coefficient k1
Details of setting A and k2A will be described later). However, when going straight, the determination in Z7 is NO and the process moves to Z8. At this time, the correction coefficients k1, k2, k1A,
Both k2A are set as 1 as a reference value, and the left and right rear wheels 1R
The target wheel speeds of L and 1RR are made equal to each other. After Z8 or Z9, at Z10,
Target wheel speed VTRL (VTRR) to rear wheel 1RL (1R
The amount Q of oil supplied to the motor ML (MR) is determined according to the value obtained by subtracting the actual wheel speed VBL (VBR) of R). This oil liquid amount Q is independently determined for the left and right motors ML and MR. And Z1
In 1, the switching valves VVB · L and VVB · R are independently controlled so that the determined oil liquid amount Q is realized. Thereafter, at Z12, it is determined whether or not the road surface is in the low μ state. If YES in the determination at Z12, that is, if the road surface is in the low μ state, the left and right rear wheels 1 are sent at Z13.
Motor M so that slip does not occur in RL and 1RR
The slip ratio SR for regulating the driving force of the L and MR is multiplied by 0.8 to set the slip ratio SR low, while when NO, the left and right rear wheels 1RL, 1RL at Z14.
The slip ratio SR of the RR is made equal to the slip ratio SF of the front left and right wheels 1FL, 1FR, and then the process is returned. That is, here, on low μ roads, the left and right rear wheels 1RL, 1RR are less likely to slip, so that the grip force on the road surface is made larger than that of the left and right front wheels 1FL, 1FR, and the yaw rate in the turning direction of the vehicle is increased. It is designed to maintain high turning performance without overrunning. Therefore, Z
The friction coefficient detecting means 93 according to the invention of claim 7 is constituted by 12 and the slip ratio changing means 94 is constituted by Z13. In the normal drive control in the integrated mode, the processes of Z5 to Z9 are unnecessary, and the target vehicle speed VTR determined by Z2 becomes the target wheel speeds VTRL and VTRR of the left and right rear wheels 1RL and 1RR. Also, the flow rate Q at Z11
The switching valve VVA is used to realize the above.

[Explanation of Turning Performance Control Flowchart (FIG. 12)] FIG. 12 shows the left and right rear wheels 1 when turning as described above.
By setting the correction coefficients k1A and k2A by which the target wheel speeds VTRL and VTRR of RL and 1RR are set, the motors ML and
The details of the control for improving the turning performance by generating a predetermined yaw rate in the vehicle by the driving force of the MR are shown. To explain the outline of this control, when the vehicle is turning at high speed, the rotational driving force of the turning outer wheel is increased to generate the necessary yaw rate in the turning direction on the vehicle body, while the vehicle is turning at medium or low speed. At times, the respective correction coefficients k1A and k2A are set so as to reduce the rotational driving force of the inner turning wheel to generate the necessary yaw rate in the turning direction on the vehicle body. The setting operation of the correction coefficients k1A and k2A will be specifically described below. After the start, it is determined whether or not the turning performance control flag F is set to 1 in Z71, and when the turning performance control flag F is not set to 1 in this determination of Z71, NO
At Z72, it is determined whether or not the steering angular velocity calculated based on the steering wheel steering angle detected by the steering wheel steering angle sensor S8 is equal to or higher than a predetermined value. When the steering wheel angular velocity is NO which is smaller than the predetermined value in the determination of Z72, it means that the vehicle is not in a turning state or is traveling on a very gentle curve, and it is not necessary to generate a yaw rate in the vehicle body so that the turning performance control is performed. Will be returned without doing. On the other hand, if the steering wheel angular velocity is equal to or greater than the predetermined value in the determination of Z72, it is determined in Z73 whether the ground vehicle speed VA detected by the ground vehicle speed sensor S5 is equal to or higher than the predetermined value V0. If the ground vehicle speed VA is equal to or higher than the predetermined value V0 in the determination of Z73, the correction coefficient k1A corresponding to the absolute value of the steering angular velocity is set in Z74. The correction coefficient k1A is a value of 1 or more, and in a region where the steering angular velocity is equal to or greater than a predetermined value, the correction coefficient k1A is set to a larger value as the steering angular velocity increases. On the other hand, if the ground vehicle speed VA is smaller than the predetermined value V0 in the determination of Z73, NO
At this time, the correction coefficient k2A is set in Z75 according to the absolute value of the steering angular velocity. The correction coefficient k2A is a value of 1 or less, and is set to a smaller value as the steering angular velocity is higher in a region where the steering angular velocity is a predetermined value or more. Then, after the correction coefficients k1A and k2A are set according to the ground vehicle speed and the steering angular speed in this way, Z
At 76, the turning performance control flag F is set to 1,
The values set here are substituted into the correction coefficients k1A and k2A of Z8 and Z9 in the independent mode positive drive flowchart (FIGS. 10 and 11) described above, and the left and right rear wheels 1R are set.
The target vehicle speeds VTRL and VTRR of L and 1RR are calculated. Further, when k1A is set in Z74, k2A is set to 1 as a reference value, and conversely, Z75 is set.
When k2A is set in, k1A is set to 1 as a reference value. Therefore, when the vehicle is turning at high speed, the rotational driving force of the outer turning wheel is increased to generate the necessary yaw rate in the turning direction on the vehicle body, while at the time of turning at medium to low speed operation, the inner turning wheel is driven to rotate. The target vehicle speeds of the left and right rear wheels are given so as to reduce the force and generate the necessary yaw rate in the turning direction in the vehicle body. Therefore, Z8, Z9 and Z74, Z75, Z7
6, yaw rate adjusting means 90, Z72 constitutes turning detection means 92, and Z73 constitutes vehicle speed state recognizing means 91. As described above, the reason why the wheels to be controlled differ according to the vehicle speed is that the behavior of the vehicle body is likely to greatly occur when the yaw rate is generated by braking to change the vehicle body posture. The rotational driving force of the turning outer wheel is increased for the purpose of generating the required yaw rate while maintaining a stable high-speed operation state without causing this behavior. Specifically, it is a case where the turning performance is improved while maintaining a stable high-speed driving state in a situation where the vehicle is traveling on a highway and the road curves. On the other hand, during medium to low speed driving, this behavior is positively generated to change the body posture quickly to improve the vehicle's kinetic performance and achieve agile movement. Is being reduced. Specifically, this is a case where the vehicle's kinetic performance is improved when the vehicle is traveling on a winding road. Then, in such a turning performance control state, YES is determined in Z71, and thereafter, it is returned to the straight traveling state in Z77, that is,
It is determined whether or not the vehicle has deviated from the curve of the road, and in this determination of Z77, the vehicle has not yet returned to the straight traveling state NO
When, the yaw rate sensor S15 is set at Z78.
It is determined whether the yaw rate of the vehicle body detected by exceeds a peak value (maximum value). And this Z78
When the determination is NO, that is, when the yaw rate has not yet exceeded the peak value, the routine returns to Z73, and the turning performance control as described above is continuously performed. On the other hand, when the yaw rate exceeds the peak value in Z78, YES in Z79.
At, it is determined whether or not the control state in which the correction coefficient k1A is changed, that is, the high-speed operation state in which the outer turning wheel is controlled. The correction coefficient k1 is determined by the determination of Z79.
When A is the changed control state, YES, Z80
In, the correction coefficient k1A is multiplied by 0.9 to reduce the value. On the other hand, if NO in the control state where the correction coefficient k1A is changed in the determination of Z79, the correction coefficient k2A is returned to the reference value 1 in Z81, and then in Z80, the correction coefficient k1A is multiplied by 0.9 to be reduced. . In this way, the correction coefficient k1A can be reduced or the correction coefficient k1A can be reduced.
By reversing the magnitude relationship between A and k2A, the oversteer running state of the vehicle in the latter half of the turn is canceled and the vehicle is returned to the neutral steer running state, and the vehicle body posture is directed toward the escape direction of the curve. I am trying to improve the escape rate. In other words, if the vehicle remains in the oversteer state, it will not be able to apply the acceleration force toward the escape direction of the curve, so near the exit of this curve, the vehicle will quickly return to the neutral steer state. Therefore, the vehicle can be accelerated. When YES in Z77, the turning performance control flag is set to 0, and then in Z83, the correction coefficients k1A and k2 are set.
A is returned to the reference value 1. Due to such a turning state, it is possible to improve the turning performance without providing a conventional four-wheel steering device, and
In the high-speed operation state, the turning performance can be improved without lowering the vehicle speed, and in the medium-low speed operation state, the required yaw rate can be quickly generated.
Further, as an embodiment according to the invention as claimed in claim 2, the rotational driving force of only one of the left and right rear wheels 1RL, 1RR is adjusted, that is, only the turning outer wheel at high speed operation, and only the turning inner wheel at medium and low speed operation. Is adjusted so that the driving force is not applied to the other rear wheel, it is possible to generate an appropriate yaw rate in the turning direction in the vehicle while suppressing the energy consumption of the motors ML and MR.

[Description of Independent Mode Reverse Driving Flowchart (FIG. 13)] FIG. 13 shows the details of the reverse driving in the independent mode. The reverse drive control in the integrated mode is different from the changeover valve used in the independent mode only in the switching valve used for the flow rate adjustment, and the other operations are performed in the same manner as the forward drive control in the independent mode.

First, after various signals are input in Z21, it is determined in Z22 whether the reverse drive flag is 1 or not. If NO in this determination of Z22, Z3
At 0, it is confirmed where the current state is in the region set by using the steering angle and the vehicle speed VA as parameters. After this, in Z31, the current state is Z
It is determined whether or not there is a hatched C area in the area indicated by 30. If YES in the determination of Z31,
After the reverse drive flag is set to 1 in Z32, Z2
Returning to 1 and if the determination in Z31 is NO, the process returns to Z21 without passing through Z32. When Z32 has passed, the determination of Z22 is YES, and at this time, it is determined in Z23 whether or not ABS control is currently being performed. This Z23
If the determination is NO, it is determined in Z24 whether the brake depression amount is large. If NO in Z24, the vehicle speed VA is set to the predetermined value V3 in Z25.
It is determined whether or not the following low vehicle speed is reached. If NO in Z25, in Z26, the motors ML and MR are set using the vehicle speed VA and the shift position of the transmission 4 as parameters.
The supply flow rate Q for is determined. Thereafter, in Z27, the flow rate Q determined in Z26 is set to the left and right motors ML,
Switching valves VVB ・ L, VVB ・
R is controlled. After Z27, the processes of Z28 and Z29 are performed. This process corresponds to the processes of Z12 and Z13 in FIG. 11, and is a process for correcting the reverse driving force becoming too large. If YES in any of Z23, Z24, and Z25, the reverse drive control is stopped in Z33, and then the reverse drive flag is set to 0 in Z34.
Is reset to. In the reverse drive control in the integrated mode, VVA is used as a switching valve that realizes the flow rate Q determined in Z26.

[Explanation of Traction Control Flowchart (FIGS. 14 and 15)] FIGS. 14 and 15 show E of FIG.
This is performed when the determination in step 24 is YES, and is drive assist control (independent left and right forward drive) using the motors ML and MR when the traction control is being executed by the control unit U3. First, after various signals are input in Z41, in Z42, the front wheel 1F caused by the traction control of the control unit U3.
Reduction amount of torque applied to L and 1FR, that is, engine 2
The torque reduction amount TF generated in the above is read based on the signal from the control unit U3. After this, in Z43,
The vehicle speed reduction amount VC is determined according to the torque reduction amount TF. At Z44, the supply flow rate Q to be supplied to the motors ML and MR is determined according to the vehicle speed reduction amount VC. The supply flow rate Q is determined so that the total generated torque of the motors ML and MR becomes the same as the generated torque reduction amount of the engine 2. After that, in Z45, it is determined whether or not the traction control is stopped. If NO in Z45, the lateral G acting on the vehicle body is calculated in Z46 based on the vehicle speed VA and the steering angle of the steering wheel. After this,
In Z47, the correction factors F1 and F based on the lateral G are
2 is set. That is, here, the motors ML and MR corresponding to the outer turning wheel and the inner turning wheel that cause a rotation difference during turning.
A correction coefficient for determining the distribution ratio of the supply flow rate to, that is, the torque distribution ratio is obtained. And Z
At 48 (FIG. 15), it is determined whether or not the vehicle is making a right turn. If YES in the determination of Z48, in Z49, the supply flow rate QTRL of the oil liquid to the motor ML that drives the left rear wheel 1RL is multiplied by the correction coefficient F1 with respect to the supply flow rate Q determined in Z44. Similarly, the supply flow rate QTRR of the oil liquid to the motor MR that drives the right rear wheel 1RR is calculated by multiplying the supply flow rate Q determined in Z44 by the correction coefficient F2.
If NO in Z48, in Z50,
It is determined whether or not it is a left turn. If YES in the determination of Z50, the supply flow rate QTRL of the oil liquid to the motor ML for driving the left rear wheel 1RL is Z4 in Z51.
It is calculated by multiplying the supply flow rate Q determined in 4 by the correction coefficient F2, and similarly, the supply flow rate QTRR of the oil liquid to the motor MR for driving the right rear wheel 1RR is Z4.
It is calculated by multiplying the supply flow rate Q determined in 4 by the correction coefficient F1. Furthermore, NO in the determination of Z50
At this time, since the vehicle is in a straight traveling state, at Z52, the supply flow rates QTR (L, R) of the oil liquid to the motors ML, MR are
It is calculated by multiplying the supply flow rate Q determined in Z44 by 0.5. After all, the processing of Z47 to Z52 corresponds to the processing of increasing the driving force on the turning outer wheel side and decreasing the driving force on the turning inner wheel side. After such processing, in Z53, the determined oil liquid amount QTR (L,
R) to realize the switching valve VVB / L, VVB / R
Are independently controlled. At Z54, the vehicle speed V
It is determined whether or not the value obtained by subtracting the actual wheel speed VBL of the left rear wheel 1RL from A is smaller than the predetermined speed "-V4". The determination of Z54 is, after all, the left rear wheel 1
This is a determination as to whether or not the actual wheel speed VBL of the RL is too large compared to the vehicle speed VA, and the determination of Z54 is YES.
At this time, in Z55, correction is made to reduce the supply flow rate Q so that the rear wheels maintain the predetermined slip value. The processing of Z54 and Z55 is similarly performed for the right rear wheel 1RR. If NO in the determination of Z54, the process returns without passing through Z55.

[Description of Stop Mode Flowchart (See FIG. 1
6)] FIG. 16 shows the control contents of the stop mode in D9 of FIG. First, after various signals are input in Z61, it is determined in Z62 whether or not the accelerator is depressed. In the case of NO in Z62, after the target vehicle speed VTR is set to 0 in Z63, the actual wheel speed VBL or VBR of the left and right rear wheels 1RL, 1RR becomes the target vehicle speed VTR in Z64. , The supply flow rates to the motors ML and MR are feedback-controlled (right and left independent control).
By the way, when the transmission 4 is an automatic transmission (in this case, the clutch 3 is a torque converter), as is called creep, traveling at an extremely low speed is possible even if the accelerator is not stepped on. It is supposed to be done. If the target vehicle speed VTR is set to, for example, 5 km / h in order to obtain this creep, the creep speed can always be kept constant regardless of the slope of the road surface while the vehicle is stopped. Then, the target vehicle speed VTR can be manually selected, for example, in the range of 0 to 15 km / h in a continuously variable manner or in a stepless manner (when the target vehicle speed is 0, no creep occurs).

Although one embodiment according to the present invention has been described above, as an embodiment according to the invention described in claim 6, the vehicle speed state of the vehicle may be recognized based on the speed change gear position. In this case, the vehicle speed is estimated by the gear position detected by the gear position detection sensor S6, the vehicle speed is recognized as being low when the shift gear is in the low speed gear position, and the vehicle speed is high when the shift gear is in the high speed gear position. When the vehicle speed is recognized, the correction coefficients k1A and k2A are set to generate the required yaw rate. As described above, the vehicle speed state recognizing means 91 according to the present invention.
In addition to the ground vehicle speed, the vehicle speed state recognized by means of the speed change gear position, the engine speed, a combination thereof, and the like. Further, in this example, the control for improving the turning performance by the driving force is performed in the independent positive drive mode, but the LSD is performed at E45 in FIG. 6 or E66 in FIG.
The mode may be canceled and the independent drive mode may be performed to perform control for improving the turning performance by the driving force.

Although the embodiment has been described above, the present invention is not limited to this, and includes the following cases, for example.

(1) The mode selected by the manual switch (integrated mode or independent mode) and D1 in FIG.
2 (FIGS. 5 to 8), when the control condition is satisfied (integrated mode or independent mode), the drive assist using the motors ML and MR may not be performed at all.

(2) In the case of a bad road, the drive assistance using the motors ML and MR may be performed in the same manner as in the case of a good road.

(3) Prioritizing the mode selection by the manual switch, the control areas of the integrated mode and the independent mode depending on the rough road may be set.

Further, only the control in the independent mode may be permitted on the bad road, while the control in the integrated mode may be permitted on the slow road. On the contrary, only the control in the integrated mode may be permitted on the bad road, while the control in the independent mode may be permitted on the slow road.

(4) Left and right rear wheels 1RL, 1RR are engine 2
Drive the left and right front wheels 1FL, 1FR by the motor ML,
It may be driven by MR. Of course, the motor M
The L and MR may be electrically driven, and the motors ML and MR may be constantly used during driving.

(5) When traveling straight, set the independent mode at low speed,
The integrated mode may be used at high speed. Such settings are
Although it can be performed on a high μ road, it is particularly preferable to perform on a low μ road in order to satisfy the improvement of running performance at low speed and the straight running stability at high speed.

[0074]

As described above, according to the present invention, the following effects can be obtained. According to the first aspect of the invention, the motor driving force adjusting means receives the signal from the vehicle speed state recognizing means, and when the vehicle turns, the rotational driving force generated on the left and right auxiliary driving wheels is individually generated according to the vehicle speed state. Since the vehicle is provided with the yaw rate adjusting means for controlling the driving force of the motor so that the yaw rate in the turning direction is generated, the driving force of the motor can exert a steering function. It is possible to improve turning performance without providing a four-wheel steering device.

According to the second aspect of the present invention, the yaw rate adjusting means controls the driving force of the motor so as to adjust the rotational driving force of only one of the left and right auxiliary driving wheels and turns the vehicle. Since the yaw rate in the direction is generated, it is possible to generate an appropriate yaw rate in the turning direction in the vehicle while suppressing the energy consumption of the motor.

According to the third aspect of the present invention, when the vehicle speed state is a low vehicle speed state, the yaw rate adjusting means controls the driving force of the motor so as to reduce the rotational driving force of the turning inner wheel, thereby turning the vehicle. Direction yaw rate is generated, and especially when the vehicle body attitude is changed by generating a yaw rate by braking, the behavior of the vehicle body is likely to occur greatly. It is possible to improve the kinetic performance of the vehicle by making various changes in the body posture.

According to the fourth aspect of the present invention, the yaw rate adjusting means controls the driving force of the motor so as to increase the rotational driving force of the turning outer wheel when the vehicle speed state is a high vehicle speed state, thereby turning the vehicle. By generating the yaw rate in the direction, it is possible to generate the required yaw rate while maintaining a stable high speed operation state without generating the above-described behavior during high speed operation.

According to the fifth aspect of the present invention, the turning detection means for detecting the turning of the vehicle is provided, and the yaw rate adjusting means receives the detection signal of the turning detection means and responds to the vehicle speed condition when the vehicle turns. Since the yaw rate in the turning direction is generated in the vehicle by individually adjusting the rotational driving force generated on the left and right auxiliary drive wheels, the turning of the vehicle can be surely recognized and the control malfunction can be prevented.

According to the sixth aspect of the invention, the vehicle speed state recognizing means is adapted to recognize the vehicle speed state of the vehicle based on the speed change gear position, and the vehicle speed state recognizing means has the speed change gear at the low speed gear position. In this case, the vehicle speed state is recognized as the low vehicle speed state, and when the transmission gear is in the high speed gear position, the vehicle speed state is recognized as the high vehicle speed state.
It is possible to easily recognize the vehicle speed state of the vehicle.

According to the seventh aspect of the present invention, the friction coefficient detecting means for detecting the friction coefficient of the road surface is provided, and the motor driving force adjusting means is provided so as to prevent the auxiliary driving wheel from slipping. Slip rate changing means for changing the slip rate for regulating the rotational driving force is provided, and when the slip rate changing means receives the output of the friction coefficient detecting means and the friction coefficient of the road surface is low, the auxiliary drive wheel is provided. Since the slip ratio of the vehicle is set to a value different from the slip ratio of the main drive wheels, the body posture can be adjusted by changing the grip force of the front and rear wheels with respect to the road surface, and the turning performance is further improved. be able to.

According to the present invention, the yaw rate detecting means for detecting the yaw rate of the vehicle body is provided, and the yaw rate adjusting means receives the output of the yaw rate detecting means and the yaw rate of the vehicle body reaches the maximum value during turning. The motor drive force is controlled so that the yaw rate generated in the vehicle during this turn becomes smaller when the vehicle crosses the crossing.Therefore, the posture of the vehicle body during the latter half of the turn can be oriented toward the escape direction of the curve. The escape rate can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a diagram showing a hydraulic system of a vehicle according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a control system.

FIG. 4 is a diagram showing a main flowchart of motor drive control.

FIG. 5 is a diagram showing a part of a flowchart of mode determination control.

FIG. 6 is a diagram showing a part of a flowchart of mode determination control.

FIG. 7 is a diagram showing a part of a flow chart of mode determination control.

FIG. 8 is a diagram showing a part of a flowchart of mode determination control.

FIG. 9 is a diagram showing a flowchart of execution determination control.

FIG. 10 is a diagram showing a part of a flowchart of independent positive drive control.

FIG. 11 is a diagram showing a part of a flowchart of independent positive drive control.

FIG. 12 is a view showing a flowchart of turning performance control.

FIG. 13 is a diagram showing a flowchart of independent reverse drive control.

FIG. 14 is a diagram showing a part of a flowchart of traction control.

FIG. 15 is a diagram showing a part of a flowchart of traction control.

FIG. 16 is a diagram showing a flowchart of control in a vehicle stop mode.

[Explanation of symbols]

1FL, 1FR Front wheel (main drive wheel) 1RL, 1RR Rear wheel (auxiliary drive wheel) 2 Engine ML, MR motor U1 Main control unit (motor drive force adjusting means) 90 Yaw rate adjusting means 91 Vehicle speed state recognizing means 92 Turn detecting means 93 Friction coefficient detecting means S15 Yaw rate sensor (yaw rate detecting means)

Claims (8)

[Claims] 1. A vehicle in which one of the left and right front wheels and the left and right rear wheels is a main drive wheel for receiving a driving force of an engine, and the other wheel is an auxiliary drive wheel for receiving a driving force of a motor, The motor drive force adjusting means for adjusting the drive force of the motor, and the vehicle speed state recognizing means for recognizing the vehicle speed state corresponding to the ground vehicle speed of the vehicle are provided, and the motor drive force adjusting means includes the vehicle speed state recognizing means. In response to the signal, the yaw rate in the turning direction is generated in the vehicle by controlling the driving force of the motor so that the rotational driving force generated in the left and right auxiliary drive wheels is individually adjusted according to the vehicle speed when the vehicle turns. A drive device for a vehicle, which is provided with yaw rate adjusting means for controlling the yaw rate. 2. The yaw rate adjusting means controls the driving force of the motor so as to adjust the rotational driving force of only one of the left and right auxiliary driving wheels to generate a yaw rate in the turning direction of the vehicle. The drive device for a vehicle according to claim 1, wherein the drive device is configured as follows. 3. The yaw rate adjusting means generates a yaw rate in the turning direction of the vehicle by controlling the driving force of the motor so as to reduce the rotational driving force of the turning inner wheel when the vehicle speed state is a low vehicle speed state. The drive device for a vehicle according to claim 1 or 2, wherein the drive device is configured. 4. The yaw rate adjusting means generates a yaw rate in the turning direction in the vehicle by controlling the driving force of the motor so as to increase the rotational driving force of the turning outer wheel when the vehicle speed state is the high vehicle speed state. The drive device for a vehicle according to claim 1 or 2, wherein the drive device is configured. 5. A yaw rate adjusting means is provided with a turning detection means for detecting turning of the vehicle, and the yaw rate adjusting means receives a detection signal from the turning detection means and generates rotation in left and right auxiliary drive wheels according to a vehicle speed state when the vehicle turns. The drive system for a vehicle according to claim 1, wherein the drive force is individually adjusted to generate a yaw rate in the turning direction in the vehicle. 6. The vehicle speed state recognizing means is adapted to recognize the vehicle speed state of the vehicle based on the speed change gear position, and recognizes that the vehicle speed state is a low vehicle speed state when the speed change gear is at the low speed gear position. The drive device for a vehicle according to claim 1, wherein when the shift gear is in a high speed gear position, the vehicle speed state is recognized as a high vehicle speed state. 7. A friction coefficient detecting means for detecting a friction coefficient of a road surface, wherein the motor driving force adjusting means is a slip for restricting a rotational driving force of the auxiliary driving wheel so that the auxiliary driving wheel does not slip. The slip ratio changing means receives the output of the friction coefficient detecting means, and when the friction coefficient of the road surface is low, the slip ratio changing means changes the slip ratio of the auxiliary driving wheel to the main driving wheel. The vehicle drive device according to claim 1, wherein the drive device is configured to have a value different from the slip ratio. 8. A yaw rate detecting means for detecting a yaw rate of a vehicle body, wherein the yaw rate adjusting means receives an output of the yaw rate detecting means and, when the yaw rate of the vehicle body exceeds a maximum value during turning, the vehicle is turned during this turning. 2. The vehicle drive device according to claim 1, wherein the drive force of the motor is controlled so that the generated yaw rate becomes small.