JPH0350029A - Driving torque distribution device for vehicle - Google Patents

Abstract

PURPOSE:To improve turning round property of a vehicle at high speed running by constituting the device so that operation of a driving torque distribution changeable means is controlled to increase transmission quantity of driving torque to the reverse side wheel against the steering speed direction according to magnitude of the steering speed by a controller. CONSTITUTION:A controller 34 controls operation of a driving torque distribu tion changeable means (composed of a hydraulic motor 11, a control valve 26, an oil pump 22) so as to increase transmission quantity of driving torque to the reverse side wheel against the steering speed direction detected with a steering angular speed sensor 35 according to magnitude of the detected steering speed, to change distribution ratio of the torque with a differential device 1. Hereby at turning-in of a steering wheel, distribution of the driving force to the wheel on the outside of turning is increased, and at turning-return of a steering wheel, distribution of the driving force to the wheel on the outside of turning is increased. Hence, yawing response, namely, turning round property of the vehicle is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a drive torque distribution device used in a vehicle drive system to actively control the distribution of drive torque transmitted to left and right wheels.

(Prior Art) Conventionally, as a drive torque distribution device that actively controls the distribution of drive torque transmitted to left and right wheels, Japanese Patent Application Laid-Open No. 62-1999
One disclosed in Japanese Patent No. 94423 is known. In this conventional example, when driving at low speeds, the steering characteristics of the vehicle are set to oversteer by increasing the torque distribution to the wheels on the outside of the turn, and when driving at high speeds, the torque distribution to the wheels on the inside of the turn is increased to set the vehicle's steering characteristics to the oversteer side. The steering characteristic is set to the understeer side.

(Problems to be Solved by the Invention) However, although the above-mentioned conventional example improves the turning performance of the vehicle at the beginning of a turn when running at low speed, there is a risk that the vehicle tends to oversteer constantly during a turn, which may impair safety. When driving at high speeds, understeer tends to occur, which improves the stability of the vehicle when turning, but it has the disadvantage that the vehicle's yaw response at the beginning of a turn deteriorates, reducing the turning ability of the vehicle and impairing the turning feeling. there were.

(Structure of the Invention) The present invention was devised in view of the above points, and includes a differential device configured to distribute and transmit drive torque input from an engine to left and right wheels, A drive torque distribution variable means provided to be able to change the torque distribution ratio by the device; a steering speed detection means for detecting the steering speed of the steering wheel; and a drive torque distribution variable means that detects the steering speed of the steering wheel; and control means for controlling the operation of the distribution variable means, and the control means controls the amount of drive torque transmitted to the wheels on the opposite side to the direction of the detected steering speed in accordance with the magnitude of the detected steering speed. A drive torque distribution device for a vehicle, characterized in that the drive torque distribution variable means is configured to control the operation of the drive torque distribution variable means so as to increase the drive torque distribution.

(Operation) According to the present invention, the control means controls the amount of drive torque transmitted to the wheels on the opposite side to the direction of the steering speed detected by the steering speed detection means, depending on the magnitude of the detected steering speed. controlling the operation of the drive torque distribution variable means to increase the torque distribution;
Since the torque distribution ratio by the differential is changed, when the steering wheel is turned, the distribution of driving force to the wheels on the outer side of the turn increases, and when the steering wheel is turned back, the distribution of driving force to the wheels on the outer side of the turn is increased. This increases the distribution of driving force. Therefore, the vehicle's yaw response, that is, its turning performance is improved.

In addition, since the control amount of torque distribution by the operation of the drive torque distribution variable means is in accordance with the magnitude of the steering speed,
At the beginning of steering, the turning performance of the vehicle is effectively improved, and in areas where the steering speed is low, such as in a state where the steering is held, the amount of control by the drive torque distribution variable means is reduced, and torque distribution is mainly performed by the action of the differential gear. This ensures stable turning.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

Referring to FIG. 2, the differential device 1 includes a differential case 3 having a ring gear 2, and left and right idle gears 7. which mesh with pinion gears 4 provided on the differential case 3 and are connected to left and right output shafts 5.6, respectively. 8, and the ring gear 2 of the differential case 3 meshes with a drive pinion 10 provided on the shaft 9. The shaft 9 receives driving force from the engine side (not shown). Therefore, the driving force transmitted from the shaft 9 to the ring gear 2 rotates the differential case 3, and the left and right side gears 7° are rotated via the pinion gear 4. 8 (output shaft 5.
6), the driving torque is distributed and the distributed driving torque is transmitted to the left and right wheels. Here, the ring gear 2 and differential case 3 serve as input members, and the left and right output shafts 5.6 and side gears 7.8 serve as left and right output members.

A hydraulic motor 11 is provided between the differential case 3 and the left output shaft 5. This hydraulic motor 11 is a reversible type whose rotation direction can be reversed, and its rotational output causes the differential case 3 to It rotates relative to the left output shaft 5.

The hydraulic motor 11 is of a vane pump type, and as shown in FIG. The inner circumferential side of the casing 13, which is formed in the shape of a cam ring, is connected to the inner circumferential side of the differential case 3. The hydraulic motor 11 has a large number of holes gB15 formed at equal intervals in the circumferential direction on the outer peripheral surface 14 of the rotor 12, and a ring 16 is inserted into each of the large number of holes 15 via a spring (not shown). It is fitted. For this reason, each vane 16
is brought into sliding contact with the cam ring-shaped inner peripheral portion of the casing 13 by the biasing force of a spring.

Three pressure chambers 17 are formed at equal intervals in the circumferential direction between the rotor 12 of the hydraulic motor 11 and the casing 13. Bow) 18 and 19 are open respectively. Each of these ports 18 is connected in parallel by an oil passage 20, and each port 19 is connected in parallel by an oil passage 21. For this reason, the hydraulic motor 11
When high oil pressure is introduced into the oil passage 20, high pressure oil flows in from the port 18, the rotor 12 rotates clockwise in FIG. 1 relative to the casing 13, and high oil pressure is introduced into the oil passage 21. High pressure oil flows in from the port 19, causing the rotor 12 to rotate counterclockwise in FIG. 1 relative to the casing 13. In addition, each oil passage 20.21 is the first
As shown in the figure, annular oil passages 30, 31, . It communicates with each port 18, 19 through communication passages 32, 33 bored in the differential case 3.

On the other hand, as shown in FIG. 2, the hydraulic pump 22 serving as a hydraulic pressure source is driven by the aforementioned shaft 9 to suck in oil from the reservoir 23 and discharge it. Since the shaft 9 rotates in proportion to the rotation of the output shaft of the transmission, the hydraulic pump 22 rotates in accordance with the vehicle speed, and the flow rate of oil discharged is proportional to the vehicle speed. Between the supply oil passage 24 communicating with the discharge port of the hydraulic pump 22 and the return oil passage 25 communicating with the reservoir 23 and the aforementioned oil passages 20 and 21, there is provided a system for controlling the hydraulic state acting on the hydraulic motor 11. An electromagnetic control valve 26 is provided. Furthermore, as shown in FIG. 1, a bypass oil passage 27 connected to the supply oil passage 24 and the return oil passage 25 is provided with an upper limit for the flow rate of oil supplied from the hydraulic pump 22 to the control valve 26 side. A flow control valve 28 is provided. In addition, the above-mentioned hydraulic motor 11
° Control valve 26. The hydraulic pump 22 constitutes drive torque distribution variable means.

The control valve 26 is composed of a throttle control type spool valve, and its operating direction is changed by the current selectively supplied to the left and right solenoid coils 37 and 36, and the high oil pressure is controlled depending on the operating direction. The supplied oil path (that is, the rotation direction of the hydraulic motor 11) is switched,
The magnitude of the hydraulic pressure output is determined by the stroke amount determined by the magnitude of the supplied current (i.e., the hydraulic motor 1
1 rotation speed) changes. Note that when neither of the solenoid coils 37 and 36 is energized, the control valve 26 is held at the neutral position by the neutral spring, and when the control valve 26 is at the neutral position, the oil passage 2
0 and 21 are in an equal pressure state, so the hydraulic motor 11 does not rotate.

The operation of the control valve 26 is controlled by the drive current output from the controller 34 to the left and right solenoid coils 37,36.
Reference numeral 4 controls the drive current to be output based on the detection output of a steering angular velocity sensor 35 that detects the steering angular velocity of the steering wheel.

The control operation performed in the controller 34 will be explained based on FIG. 3. First, in step Sl, the steering angular velocity d detected from the steering angular velocity sensor 35 is read, and then in step S2, the 0-i shown in FIG. 4 is read. The current value i to be output is read from the map, and then in step S3 a drive current output according to the read current value 1 is supplied to the control valve 26. In addition, step S
3, the process returns to step S1 and the subsequent processing is repeated.

Here, as is clear from FIG. 4, a dead zone is provided near the neutral position of the steering angular velocity θ, and the current value i output when the steering angular velocity θ exceeds the dead zone is
In consideration of the starting force of No. 6, the current value i is started from a certain value or more, and the output current value i increases in proportion to an increase in the steering angular velocity θ.

Next, the operation of this embodiment having the above configuration will be explained.

When the steering angular velocity θ detected by the steering angular velocity sensor 35 is in the dead zone region shown in FIG. Since no current is output, control valve 26 is maintained in a neutral position. Therefore, each port 18, 19 of the hydraulic motor 11 is in an equal pressure state, and the hydraulic motor 11 does not rotate due to hydraulic pressure.

Therefore, in this state, the differential operation is performed only by the action of the differential gear @1, and the torque distribution is similar to that of a boat fishing vehicle.

Further, when the steering wheel is steered relatively quickly, the steering angular velocity detected by the steering angular velocity sensor 35 is the fourth.
If the steering angular velocity is outside the dead zone shown in the figure, the steering angular velocity should be 6.
A drive current value i corresponding to the current value is supplied from the controller 34 to the solenoid coil of the control valve 26. Now, if we consider the case where the steering wheel is steered to the right,
A current i corresponding to the steering angular velocity θ is supplied to the right solenoid coil 37, the control valve 26 is displaced to the left in FIG. ) 19 acts on each pressure chamber 17, and the high hydraulic pressure introduced from each port ) 19 causes the rotor 12 of the hydraulic motor 11 to
Relative rotation is made in the counterclockwise direction as shown by the arrow in the figure. In FIG. 1, the left side of the figure is the front of the vehicle, so the rotation of the hydraulic motor 11 is caused by the rotation of the rotor 12.
This reaction force acts on the differential case 3 via the casing 13 to increase the driving force of the left drive shaft 5 .

Here, if the rotational torque of the hydraulic motor 11 is ΔT, then
As shown in FIG. 5, the torque transmitted to the left drive shaft 5 increases by ΔT, and this reaction force -ΔT acts on the differential case 3. At this time, the driving torque input from the engine is sufficiently large compared to the reaction force -ΔT transmitted to the differential case 3, so the differential case 3 is not decelerated, and the reaction force -ΔT transmitted to the differential case 3 is , -ΔT/2 is transmitted to the left and right side gears 7.8 via the pinion gear 4, respectively. Since the left side gear 7 is connected to the drive shaft 5, in the drive shaft 5, the increase ΔT in the drive torque directly transmitted from the hydraulic motor 11 is reduced by the decrease in the drive torque transmitted from the side gear 7 -ΔT/ 2 is subtracted, and the torque transmitted to the drive shaft 5 due to the rotation of the hydraulic motor 11 increases by ΔT/2.

In addition, in the right drive shaft 6, the right side gear 8
Since the drive torque transmitted from the side gear 8 decreases by -ΔT/2, the torque transmitted to the drive shaft 6 due to the rotation of the hydraulic motor 11 decreases by ΔT/2.

Therefore, when the steering wheel is quickly steered to the right, the driving force of the right rear wheel, which is the outer wheel of the turn, increases by ΔF, as shown in Figure 6, while the driving force of the left rear wheel, which is the inner wheel of the turn, increases by ΔF. The driving force will decrease by ΔF (ΔF
). Therefore, the force ΔF applied in this way causes an additional yaw moment ΔM(Δ
Fx) red) occurs, and the turning performance of the vehicle improves.

Furthermore, since the hydraulic motor 11 rotates according to the steering angular velocity of the steering wheel, the rotational output of the hydraulic motor 11 will stop when the steering is held after the above-mentioned yaw moment is generated at the beginning of a turn. , stable turning of the vehicle is guaranteed as before by the action of only the differential device l.

Further, when the steering wheel is quickly turned back from the steering state, the steering angular velocity is reversed, so a yaw moment is generated in the opposite direction to that in the above case, improving the responsiveness of returning from the turning state to the straight-ahead state.

Furthermore, since the hydraulic pressure generated by the control valve 26 changes according to the steering angular velocity and vehicle speed, the rotational output of the hydraulic motor 11 also depends on the steering angular velocity and vehicle speed, so that the vehicle can be controlled properly in a wide range of vehicle running conditions. Turning ability will be improved.

According to the above embodiment, the hydraulic motor 11 is provided in the differential l, and the rotation of the hydraulic motor 11 is controlled, thereby forcibly correcting the action of the differential and controlling the torque transmitted to the left and right wheels. Therefore, even if the hydraulic motor were to fail, the existence of the differential device 1 would prevent the vehicle from becoming unable to travel, resulting in an excellent safety effect.

In addition, since the hydraulic motor 11 is reversible, only one is needed, and the control system is one system, so the structure is relatively simple compared to conventional ones that control left and right clutches. This is an advantage.

Furthermore, since the hydraulic motor 11 is rotated in accordance with the steering angular velocity to increase the drive torque transmitted to the wheels on the opposite side to the direction of the steering angular velocity, the turning performance of the vehicle can be improved without any problems. This has the effect of improving the turning feeling of the vehicle and also improving the ability to avoid danger.

It should be noted that the present invention is not limited to the above-mentioned embodiment in any way, and it is possible to use a device having independent left and right hydraulic motors as the drive torque distribution variable means, or a device that applies independent braking force to the left and right wheels. It goes without saying that various modifications may be made without departing from the spirit of the present invention.

(Effects of the Invention) As described above in detail with the embodiments, according to the present invention, the operation of the drive torque distribution variable means provided to be able to change the torque distribution ratio by the differential device is controlled, Since the amount of drive torque transmitted to the wheels on the opposite side to the direction of the steering speed increases in accordance with the magnitude of the steering speed, the turning performance of the vehicle at the beginning of a turn is efficiently improved, and the steering speed, such as when the steering is held, is increased. In the region where the torque is small, torque is distributed mainly by the action of the differential, so stable turning is guaranteed.We provide a vehicle drive torque distribution device that can efficiently improve the turning feeling while ensuring safety. It has the effect of

[Brief explanation of drawings]

1 is a schematic configuration diagram showing an embodiment of the present invention, including a view taken along the line A-A in FIG. 2; FIG.
The figure is a flowchart showing the control operation executed in the controller 34, and FIG. 4 shows the steering angular velocity υ and the output current value i.
FIG. 5 is an action explanatory diagram showing the torque distribution action by the hydraulic motor, and FIG. 6 is an action explanatory diagram showing the action on the behavior of the vehicle. 1... Differential device, 3... Differential case. 5.6...Output shaft, 11...Hydraulic motor. 22... Hydraulic pump, 26... Control valve.

Claims (1)

[Claims] A differential device configured to distribute and transmit drive torque input from the engine to left and right wheels, a drive torque distribution variable means provided to be able to change the torque distribution ratio of the differential device, and a steering wheel. It has a steering speed detection means that detects the steering speed of the wheel, and a control means that controls the operation of the drive torque distribution variable means according to the steering speed detected by the steering speed detection means, and the control means detects the steering speed of the wheel. The drive torque distribution variable means is configured to control the operation of the drive torque distribution variable means so as to increase the amount of drive torque transmitted to the wheels on the opposite side to the direction of the detected steering speed in accordance with the magnitude of the detected steering speed. A vehicle drive torque distribution device characterized by: