JPH042526A - Four wheel drive automobile - Google Patents

Abstract

PURPOSE:To produce great driving force automatically by putting a differential gear into a direct connection condition to allow car driving in the condition of direct-connection four wheel drive when the shift range of a shift lever is a low-speed range and the opening of a throttle is in a kick-down region. CONSTITUTION:The output of an engine 2 is transmitted to a planetary gear type differential gear 12 to distribute engine torque to front wheels and rear wheels in a required condition via an automatic transmission. To the differential gear 12, a hydraulic multiplate clutch 28 is attached as a driving force distribution control means which can change the distribution of engine output torque to the front wheel and the rear wheels by locking the operation thereof. In this case, a shift lever position sensor 110 and a throttle sensor 38 are provided to input these detected signals to a controller 48. In selecting the case that a shift range is a L range or a R range and the opening of a throttle is in a kick-down region, the multiplate clutch 28 is put into a completely connected condition, resulting in the condition of direct-connection four wheel drive.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a four-wheel drive vehicle capable of controlling driving force distribution.

[Prior Art] In a four-wheeled vehicle, a drive system has conventionally been configured to control the ratio of torque transmitted to the front wheels and torque transmitted to the rear wheels according to driving conditions. Various force transmission devices are known.

For example, a driving force transmission device has been developed in which a differential limiting device such as a VCU (viscous coupling unit) is attached to the center differential to appropriately regulate the difference in rotational speed of the center differential.

It is conceivable that such a driving force transmission device performs various controls depending on the driving state of the vehicle and the like.

[Problems to be Solved by the Invention] By the way, it is possible to automatically obtain as much driving force as possible using the above-mentioned automobile driving force transmission device, especially when the driver desires a large driving force. There is a request to do so.

The present invention was devised in view of the above-mentioned problems, and an object of the present invention is to provide a four-wheel drive vehicle that can obtain as much driving force as possible when the driver desires a large amount of power. It is said that

[Means for Solving the Problems] Therefore, the four-wheel drive vehicle of the present invention is a four-wheel drive vehicle that drives the vehicle by transmitting the output torque of the engine to the front wheels and the rear wheels. a differential device that distributes torque between the front wheels and the rear wheels; and a driving force attached to the differential device that can change the state of torque distribution between the front wheels and the rear wheels by constraining the differential. The vehicle is equipped with a distribution control means, a shift range detection means for detecting the operating position of a shift lever of an automatic transmission installed in the automobile, and a throttle opening detection means for detecting the opening degree of a throttle valve of the engine. Based on calibration information from the shift range detection means and the throttle opening detection means, it is detected that the shift range is a low speed range (L range or R range) and that the throttle opening is in a kickdown region. The present invention is characterized in that a controller is provided that outputs a drive control signal to the drive force distribution control means to directly connect the differential gear.

[Function] In the four-wheel drive vehicle of the present invention described above, when the shift range of the shift lever is in the low speed range and one throttle opening is in the kickdown region, the driving force distribution means is controlled by the controller. With the differential device in the direct connection state, the vehicle is driven in the direct connection 41N4 cantering state.

[Example] Examples 1 to 17 of the present invention will be described below.
The figure shows a four-wheel drive vehicle as an embodiment of the present invention. Figure 1 is a basic block diagram of a control system showing its configuration in accordance with the content of the claims, and Figure 2 is its overall configuration. Fig. 3 is an explanatory diagram showing the configuration of the hydraulic system, Fig. 4 is a block diagram showing the relationship between each control state, Fig. 5 is a graph to explain the operating effect, Figs. 6 to 13 Each is a problem analysis diagram to explain the operation of the control system.]
-4 to 17 are graphs for explaining the operation.

In FIGS. 1 to 3 showing the configuration of this embodiment, reference numeral 2 denotes an engine, and the output of the engine 2 is transmitted to an output shaft 8 via a torque converter 4 and an automatic transmission 6.

The output of the output shaft 8 is transmitted via an intermediate gear to a planetary gear type differential bag w12 as an actuating device that distributes the engine torque between the front wheels and the rear wheels in a required state.

The output of this planetary gear type differential 12 is transmitted on the one hand to a reduction gear mechanism 19. The transmission is transmitted from the axles 17L, 17R to the left and right front wheels 16.18 via the front wheel differential gear mechanism 14, and the bevel gear mechanism 15. Propeller shaft 20 and bevel gear mechanism 21. Differential type vehicle equipment W2 for rear wheels
2 from the axles 25L and 25R to the left and right rear wheels 24.2
6. The planetary gear type differential device 12, like the conventional one, includes a sun gear 12a, a planetary gear]-2b arranged outside the sun gear 12a, and a ring gear 12c arranged outside the planetary gear 12b. and a carrier 12d that supports the planetary gear 12b.
The output of the output shaft 8 of the automatic transmission 6 is input to the sun gear 12a, and the sun gear 12a is interlocked with the front wheel differential gear device 14 via the front wheel output shaft 27 and the reduction gear mechanism 19.
2c is interlocked with the propeller shaft 20 via the rear wheel output shaft 29 and the bevel gear mechanism 15.

Further, the planetary gear type differential device 14 is provided with a hydraulic multi-disc clutch 28 as a driving force distribution control means that can change the distribution of engine output torque between the front wheels and the rear wheels by restricting its operation. ing.

That is, the hydraulic multi-disc clutch 28 is connected to the sun gear 12a (
or ring gear]-2c) and the carrier 12d, and the frictional force changes depending on the pressure applied to its own hydraulic chamber.
2c) and the carrier] and 2d.

Therefore, the planetary gear type differential device 2 appropriately controls the hydraulic multi-disc clutch 28 from a completely free state to a locked state, thereby transmitting torque to the front wheels and the rear wheels. Ring is about 33: 67 to 5
It can be controlled between 0:50. Specifically, when the pressure in the hydraulic chamber of the hydraulic multi-disc clutch 28 is zero and it is completely free, the ratio of front wheels to rear wheels is approximately 33:67 (depending on the load balance between the front and rear wheels, etc.). The pressure in the hydraulic chamber is set to the set pressure (9 kg/d), and the hydraulic multi-disc clutch 28
When the wheels are in a locked state and the differential limit becomes substantially zero, the ratio of front wheels to rear wheels becomes 50:50, resulting in a direct connection state.

Further, reference numeral 30 is a steering sensor that detects the rotation angle of the steering wheel 32 from the neutral position, that is, the steering angle θS, and 34a and 34b detect the lateral acceleration G F vGR acting on the front and rear parts of the vehicle body, respectively. Lateral acceleration sensor 36 indicates acceleration Gx in the longitudinal direction acting on the vehicle body
38 is a throttle sensor that detects the throttle opening θT of the engine 2, 39 is an engine key switch of the engine 2, 40.42.44.
46 are the left front wheel】-6, right front wheel 18, left rear wheel 26 respectively
, a wheel speed sensor that detects the rotational speed of the right rear wheel 28, and the outputs of these switches and each sensor are controlled by the controller 4.
8 is entered.

Reference numeral 50 denotes an anti-lock brake device, and this anti-lock brake device 50 operates in conjunction with a brake switch 50A. In other words, when the brake switch 50A is turned on when the brake pedal 51 is depressed, an anti-lock brake activation signal is output in conjunction with this.
Anti-lock brake device 50 is activated. Further, when the anti-lock brake activation signal is output, a signal indicating the state thereof is simultaneously input to the controller 48. Further, 52 is a controller 48
This is a warning light that lights up based on the control signal.

Note that the controller 48 includes a CPU, Roffi RAM, an interface, etc., which are not shown but are necessary for control to be described later.

Reference numeral 54 indicates a hydraulic power source, and 56 indicates a controller 48 which is interposed between the hydraulic power source 54 and the hydraulic chamber of the hydraulic multi-disc clutch 28.
Pressure control valve system (hereinafter referred to as
(abbreviated as pressure control valve).

Additionally, this car is equipped with an automatic transmission.
Reference numeral 110 is a shift lever position sensor (shift range detection means) that detects the selected shift range of the shift lever 110A of the automatic transmission, and this detection information is also sent to the controller 48.

The details of the hydraulic system related to the hydraulic multi-disc clutch 28 are shown in FIG.

That is, as shown in FIG. 3, the reservoir also serves as that of the automatic transmission 6, and the pump 58 that sucks the oil in the reservoir 6 pumps oil from its discharge port through a check valve 60 and a pressure control valve 62. and is connected to the hydraulic chamber of the hydraulic multi-disc clutch 28. The pressure control valve 62 is connected to the hydraulic multi-disc clutch 2
A first position in which the hydraulic chamber of No. 8 communicates with the pump 58 and a second position in which the hydraulic chamber communicates with the reservoir of the automatic transmission 6 can be taken.

A relief valve 64 that opens at a set pressure (9 kg/d) to release oil to the reservoir of the automatic transmission 6 is provided in the passage between the check valve 60 and the pressure control valve 62, and an accumulator 66 is provided in this passage. and a pressure switch 68 are connected. A detection signal from the pressure switch 68 is input to the controller 48. Note that the motor 58a that drives the pump 58 is controlled by a control signal from the controller 48.

Next, the traction control system 101 as engine output control means will be explained. That is,
The engine 2 is equipped with a main throttle valve 102 whose opening degree is controlled according to the amount of depression of the accelerator pedal 112, and is equipped with an accelerator pedal system engine output adjustment device (an artificial engine The sub-throttle valve 103, which constitutes the engine output control device (output control device) and serves as an engine output control means that is controlled independently of the accelerator pedal-based engine output adjustment device, is connected to the main throttle valve in the intake passage of the engine 2. 102 in series. This sub-throttle valve 103 is driven by a motor, and the motor is driven by the rear wheel speed sensors 44 and 4.
．． 6 Front wheel speed sensor 40.42, engine speed sensor]
, 04, the drive is controlled based on the detection results of the engine load sensor 105 and the like.

Such a traction control system 101
The control of the engine output by this will be referred to as driving force control (or engine output control) B hereinafter.

On the other hand, the hydraulic multi-disc clutch 28 causes a planetary gear type differential [
The control that constrains the 12 differentials is the following 5 driving force distribution control (
or center differential control) A.

Next, the operation of the controller 48, that is, the controller 48 is activated.
Block diagrams and problem analysis diagrams (PAD; ProblemAna
lysis diagram) ◇By the way, the above-mentioned center differential control A and engine output control B
That is, center differential control A is first performed, and if further control is required, engine output control B is executed in addition to center differential control A. However, depending on the type of control, engine output control B is not performed and only center differential control A is performed.

When performing center differential control A and engine output control B, first, as shown in FIG.
In this step, initial processing such as clearing a required memory area in the RAM necessary for control is performed (step al).

Then, sampling was performed every 1.5 ms (
In step a2), data input from each sensor is performed (
In step a3), it is determined whether to perform center differential control A according to the output signal of the sensor (step a4),
When it is determined that the situation is such that center differential control A should be performed, a control signal is output to the pressure control valve 62 of the driving force distribution control means 28, and the center differential control A is performed, that is, hydraulic pressure is supplied to the hydraulic chamber and the hydraulic pressure is Center differential control A that restrains the differential of the planetary gear type differential device 12 by the multi-plate clutch 28
(step a5).

Here, the decision whether to perform engine output control B is as follows:
In each control, the controller 48 determines whether the improvement in the vehicle driving state obtained by the center differential control A is insufficient (step a6), and the center differential The engine output control B is configured to be performed when control A alone is insufficient (step a7).

By the way, engine output control B is so-called traction control, and a control signal is output from the controller 48 to the traction control system 101.
Reduce the engine power to the required state.

In traction control, normally when a vehicle suddenly starts or accelerates and enters a slip state, the rear wheel speed sensor 44.46 and the front wheel speed sensor 40.42 read the difference in rotational speed between the front and rear wheels. Then, the operating state of the engine 2 is detected by the engine rotation speed sensor 104 and the engine load sensor 105, calculation is performed, and the motor is operated in accordance with the calculation result to drive the sub-throttle valve 1.3 in the closing direction. .

This controls the amount of air flowing into the engine, suppresses engine rotational torque, and suppresses slippage.

However, in this embodiment, prior to traction control, the center differential control A adjusts the distribution of driving force between the front and rear wheels to stop the front and rear wheels from spinning.

This makes it possible to stop the wheels from spinning even when the vehicle is running on a low-friction road where the wheels would otherwise spin.

Furthermore, if the center differential control A alone does not stop the wheels from spinning, engine output control B is performed to reduce the output of the engine 2, thereby reliably stopping the wheels from spinning.

The above-mentioned stopping of wheel slipping has been confirmed through experiments, and there is an advantage that wheel slipping can be reliably stopped with a good feeling.

That is, FIG. 5 shows the experimental results of the device in this example on a straight low-friction road, and in the same figure,
The curve L□ shows the change in the actual speed of the vehicle, and the curves L2 to L4
shows the wheel speed of the idling wheels converted into vehicle speed, of which curve L2 is for the center differential free state, curve L4 is for the center differential control A, and curve L4 is for the center differential control A. This is the case when engine output control B is also performed. Region (2) indicates a region where wheel slipping is suppressed by center differential control A, and region (2) shows a region where wheel slipping is suppressed by engine output control B.

In this way, by activating engine output control B& after center differential control A, and combining both controls,
For example, in less than one second after the start of control, most of the idling is eliminated.

Note that in the problem analysis diagram (PAD), step a4.
For judgment steps such as in a6, the upper right corner is Y.
The ES route and the lower right corner indicate the NO route, and those to which the next process is not connected are displayed as returning to the basic line connecting the start and end.

Further, for a step such as step a7 for which the next process is not specified, the process is displayed as returning to the basic line connecting the start and end after the process of that step.

By the way, engine output control B is performed in addition to center differential control A, mainly for control related to wheel slipping as described above.In the case of control not related to wheel slipping, only center differential control A is performed. Do this.

The controls performed in this embodiment are described in order of priority: brake switch [control (1)], high speed running control [control (2)], large driving force control [control (3)],
Spin control [control (4)], drift control [control (5)]
], longitudinal slip control [control (6)], and direct 4WD control [control (7)], and these controls are interrelated as shown in FIG.

In addition, center differential free in Figure 4 is when the brake is ON.
Control [Control (1)] and High Speed Travel Control [Control (2)]
corresponds to

Among these, the controls related to wheel slipping are spin control [control (4)], drift control [control (5)], and longitudinal slip control [control (6)].
As mentioned above, engine output control B may be performed in addition to center differential control A, but other controls [control (1)
) to (3), (7)], center differential control A
only will be done.

Each of these controls (1) to (7) will be sequentially explained below.

(1) Brake ON Control As shown in FIGS. 1 and 2, in this embodiment, the braking means (brake) is activated in response to the depression of the brake pedal 51.
50B is equipped with an anti-lock brake device 50 as a brake limiting device that limits the braking force of the braking means 50B to a required state.

The anti-lock brake device 50 is activated when the brake switch 50A is turned on, and the controller 48 receives the anti-lock brake activation signal.
Accordingly, the anti-lock brake device 50 is operated under control based on detection signals from the wheel speed sensors 40, 42, 44, 46, and the like.

On the other hand, the multi-disc clutch 28 as a power distribution control means operates normally when the brake switch 50A is in the OFF state when the brake pedal 5]- is not depressed, but when the brake pedal 51 is depressed and the brake switch 50A is in the OFF state. 50A is turned on, the controller 48 outputs an operation stop signal, that is, a hydraulic pressure supply stop signal, to the multi-disc clutch 28, and the engagement of the multi-disc clutch 28 is prohibited.

That is, the operation stop signal regulates the operation of the pressure control valve 56 so that the oil pressure in the hydraulic chamber of the multi-disc clutch 28 becomes O, and when the brake switch 50A is turned on, the center differential becomes free.

Hereinafter, this state will be referred to as center differential free.

At this time, the vehicle is driven through the driving force distribution of the planetary gear type differential device 12.

To explain the processing within the controller 48 regarding this operation, as shown in FIG. 7, the state of the brake switch 50A is input by sampling every 15 m5 (step b1.),
It is determined whether A is in the ON state (step b
2). When the brake switch 50A is in the ON state, the brake control flag is set to "1" (step b3).

Next, it is determined whether the brake control flag is "1" (step b4), and when the brake control flag is "1", it is determined whether the brake switch 50A is in the OFF state (step b5), and the brake control flag is determined to be "1". If the switch 50A is in the OFF state, the brake control flag is set to rQJ (step b6).

Next, it is determined whether the brake control flag is “1” (
After step b7), when the brake control flag is "]-", center differential free control (step b8)
), a release signal for releasing the engagement of the multi-disc clutch 28 is output from the controller 48 to the pressure control valve 56 of the multi-disc clutch.

Then, a process for setting the traction control system 101 into a non-operating state (step b9) is performed.

Therefore, when the brake switch 50A is in the ON state, steps bl, b2. b3. b4゜b5. b7. b
8. Proceeding in the order of b9, center differential free control A and processing for setting the Traxibon control system 101 into a non-operating state are performed.

On the other hand, when the brake switch 50A is switched to the OFF state, steps bl, 'b2. b4. Proceed in the order of b5 and b6, and in step b6, the brake control flag is set to "O".
can be switched to

This creates a center differential free state (step b).
8) The traction control off state l11 (step b9) is released, and the planetary gear type differential device 12 and the multi-disc clutch 28 return to normal operation.

By controlling as described above, when the anti-lock brake system 101 is activated, the operation of the driving force distribution control means 28 can be restricted to avoid control interference, and the performance of the anti-lock brake system 101 can be fully exhibited. be done.

That is, since the driving force distribution control means 12.28 controls the driving force distribution in accordance with the current driving condition, it is expected that the distribution condition will not be suitable for braking, which is not preferable from the viewpoint of avoiding danger. By performing this brake switch, priority is given to braking, so safety is sufficiently ensured.

(2) High-speed driving control As shown in FIG.
18, 24, and 26, and the traveling speed of the automobile is inputted to the controller 48 as an output signal from these.

The controller 48 outputs an activation signal to the multi-disc clutch 28 and the pressure control valve 56 as driving force distribution control means.

By the way, if the car is driven at high speeds with the multi-plate clutch 28 in operation in the same way as when it is running at low speeds, torque will flow to the front wheels, creating a dragging condition and causing power circulation.

For this reason, the multi-disc clutch 2 as a driving force distribution control means
It is desirable to stop the operation of 8 and put the center differential in the above-mentioned free state to increase the torque distributed to the rear wheels.

In addition, when driving at high speeds, centrifugal oil pressure is generated by the hydraulic oil in the multi-disc clutch 28, and at high speeds above a certain level, the center differential can be controlled to the above-mentioned free state. Become.

Under such conditions, the multi-disc clutch 28 is kept in a center differential free state in which no hydraulic pressure is supplied, in order to ensure stable high-speed running, and in order to perform other controls without delay when the vehicle deviates from high speed. This is desirable.

Therefore, this control is based on setting the center differential free during high-speed driving.

And this transition to center differential free means that the vehicle speed is V
■ The specified high speed. This is carried out in advance when it is judged that the above will definitely be reached.

In other words, o: Vehicle speed at which the center differential does not become free due to centrifugal oil pressure (constant) To: Time required for the center differential to become free from direct 4WD (constant) V: Vehicle speed a: Vehicle acceleration, then vehicle speed V is a predetermined value High speed V. The speed V' that is certain to be reached is V' = Vo-T, X a , and the center differential may be set free when v>v'.

Therefore, at this point, a deactivation signal for the multi-disc clutch 28 is output from the controller to the pressure control valve 56.

Regarding this operation, the processing within the controller 48 will be explained. As shown in FIG. At the same time, the acceleration a is calculated as a′=(Vi Vi−
x)/T (step f2).

Here, Vi is the vehicle speed according to the current sampling, Vi-1 is the vehicle speed according to the previous sampling, and T is the sampling time (
15ms).

Next, the aforementioned value V' is calculated (step f3), and it is determined whether the current vehicle speed Vi is greater than V' (step f4).

If Vl>V', the high-speed control flag is set to "1" (step f5), and V' is stored as v'' (step f6).

Next, it is determined whether the high-speed control flag is rlJ (step f7), and if the high-speed control flag is "1J", it is determined whether ■ is tJl larger than the previous v'' (
Step f8).

If the vehicle speed has decreased, V will be smaller than the previous v'', so proceed to step f9, and if the vehicle speed has not decreased, V
is not smaller than the previous v'', the process advances to step f14.

Proceeding to step f9, it is determined whether the timer is set. If the timer is not set, the timer is set (step flo), and if the timer is set, it is determined whether the timer value exceeds a certain value (step f11).

If the timer value exceeds a certain value, the high-speed control flag is set to "0" (step f12) and the timer is cleared (step f13).

On the other hand, when the process proceeds to step f14, the timer is also cleared.

Furthermore, in step f15, the high-speed control flag is set to "1".
, and the high-speed control flag is set to rlJ.
In other words, a signal to free the center differential (in other words,
A disengagement release signal for the multi-disc clutch 28 is output (step f]6).

Therefore, when the vehicle speed Vi becomes larger than V' during acceleration, steps f4, f5, f6, and so on start from step f4. f7
．． f8. f14, the timer is reset in step f14, and then step f15. Control proceeds to f16, and at step f16, control such as setting the center differential free is continued while the vehicle is accelerating. In this case, while continuing high-speed driving, step f14
The timer is cleared and continues to be reset.

Then, when the vehicle speed V becomes smaller than the previous V'', the YES route is taken at step f8, and step f9
The timer is reset via step flo.

At this time, initially, the timer is not larger than a certain value, so steps fll to f15. The process advances to f16, and the center differential free state continues without setting the high speed control flag to rQJ.

Then, in step flu, this state continues until the timer count value exceeds a predetermined value, and when the timer count value exceeds a predetermined value, the high-speed control flag is changed to rQJ (step f12). - The timer is cleared (step f13), and the center differential returns to its normal operating state.

By the way, the above-mentioned timer count is for preventing chattering, and is intended to cancel the high-speed running control when it is confirmed that the vehicle is in a deceleration state for a predetermined period of time or more.

To prevent this chattering, the vehicle speed at which the high-speed control flag is set to "1" is, for example, 14] am/h, and the vehicle speed at which the high-speed control flag is returned to "0" is set to 100 b/h, and the vehicle speed at which the high-speed control is switched to and canceled is set to 14 am/h. This may be done by providing a difference between the vehicle speed and the vehicle speed.

Note that in this control, engine output control B is not performed.

By performing such high-speed control, a situation where torque is dragged toward the front wheels is avoided, power circulation is avoided, and maximum speed running can be improved.

Furthermore, when the vehicle exits a high-speed driving state, various controls such as the center differential can be performed without delay.

(3) u Large power control As shown in FIG. 2, this embodiment is equipped with a shift lever position sensor]-10 as a shift range detection means, and a throttle sensor that detects the throttle opening oT of the engine 2. 38 are provided, and these detection signals are input to a controller 48.

The controller 48 outputs an activation signal to the multi-disc clutch 28 and the pressure control valve 56 as driving force distribution control means.

Incidentally, when the vehicle is running and the driver desires a large driving force, it is desirable to drive the vehicle in a directly coupled four-axle driving state, regardless of whether a driving force distribution control means is installed.

Therefore, this control selects the case where the shift range is in the L range or the R range and the throttle opening is in the kickdown region as when the driver wants a large driving force. By bringing the plate clutch 28 into a fully engaged state, differential movement of the planetary gear type differential device 12 is not allowed, and the direct coupling 41
1! The content is to put it in a cantering state.

Regarding this control, the processing within the controller 48 will be explained. As shown in FIG. d1), shift lever is L
Whether it is in range or R range (step d2)
, whether or not the throttle opening is in the kickdown range (step d3) are determined.

If both conditions are met, the large driving force control flag is set to rIJ.
(step d4), and step d5. d6. d
After LO, the program proceeds to steps d and 11, where direct 4WD control is performed to bring the multi-disc clutch 28 into a fully engaged state. This is done by outputting an actuation signal to the pressure control valve 56 from the controller 48 to the hydraulic pressure supply position to increase the hydraulic pressure in the hydraulic chamber.

At this time, the 1-hexion control (engine output control B), which is the control to reduce the driving force, is canceled (
Step d12).

On the other hand, if the operating condition changes and the shift range is no longer in the 1° range or the R range, the process proceeds from step d6 to step d7, and if the throttle opening becomes 50% or less, the process proceeds from step d8 to step d9. Advance,
Each step d7. At d9, set the large driving force control flag to "0"
to return to. In this case, the process does not proceed to steps sll and s12, so the direct 4WD state is canceled and the high power control state returns to the normal state.

With the above-described control, when the driver desires a large driving force, the vehicle enters direct 4WD driving, ensuring that the driving force is exerted through each wheel, and the desired power performance is obtained.

(4) Spin Control This control is based on the output signals of the shift lever position sensors 1 and 0 and the output signal of the steering angle sensor 30. This is performed on the condition that the spin condition is not in range or R range and that the spin condition is met.

The spin condition is determined by determining whether the running state is in a required range from the angular velocity θH' of the steering wheel angle θH and the yaw angular acceleration.

If the above-mentioned conditions are satisfied, the above-mentioned driving force distribution control (
Center differential control) A restricts the operation of the center differential and performs feedback control of engine output control B.

According to this control, spin is avoided and inoperability is avoided.

Also, if the spin condition is not satisfied, the wheel slip condition is not satisfied, and the shift range is not in the R or L range or the condition regarding lateral acceleration is not satisfied,
This control is canceled.

(5) Drift control This control is based on the output signal of the lever position sensor 110 and the detection signals of the lateral acceleration sensors 34a and 34b, and confirms that the shift 1 range is not in the R or L range and that the required conditions for lateral acceleration are met. It will be carried out on the condition that it is established.

In this control, center differential control A is canceled and engine output control B is performed by feedback control.

According to this control, it is possible to detect drift and avoid inoperability.

This control is performed when the shift range is the R or L range, or when the required conditions are not satisfied in the lateral acceleration, and the opening degree of the main throttle valve 102 and the sub-throttle valve 103 are changed.
It is released when the opening degree matches the opening degree of .

(6) Longitudinal slip control This control consists of the output signal of the lever position sensor 1-10, the throttle sensor 38, the wheel speed sensor 40, 42,
Based on the detection signal of 44.46, the shift range is R, L.
This is done when all of the following conditions are met: the engine is not in the range, the engine is not in an idling state, and the wheels are idling.

In this control, center differential control A is performed and engine output control B is also performed.

According to this control, wheel slipping can be detected based on the difference between the front wheel speed and the rear wheel speed, and drivability can be improved.

This control satisfies that the spin condition is not satisfied and the idling condition is not satisfied, and at the same time, either the idle state, the shift range is in the R2L range, or the steering wheel angle θH is large. It will be canceled when

(7) Direct-coupled 4WD preparation control As shown in FIG. 2, this embodiment is equipped with a hydraulic multi-disc clutch 28 in order to restrain the planetary gear type differential device 12 and control the driving force distribution state. However, during normal driving without performing other special controls (1) to (6), the multi-disc clutch 28 is controlled to an intermediately engaged state in which it is not completely engaged.

By the way, during this intermediate connection, centrifugal oil pressure is generated in the hydraulic oil in the multi-disc clutch 28 as the vehicle travels.

Furthermore, the friction plates (clutch disks) in the multi-disc clutch 28 are biased by a return spring, and the force of the return spring resists the centrifugal hydraulic pressure to achieve an intermediately engaged state.

By the way, the centrifugal oil pressure P□ in the multi-disc clutch 28 is
As shown in the graph of FIG. 4, it has a characteristic of increasing as the vehicle speed (2) increases, and depending on the vehicle speed (2), it may be larger than the return spring force FS or smaller than the return spring force FS.

Therefore, when the centrifugal oil pressure P1 is larger than the return spring force Fs, the multi-plate clutch 28 is in a directly connected state, and when it is smaller, it is in a center differential free state.

In this way, since the oil pressure at which the center differential becomes free differs depending on the vehicle speed V, if the control oil pressure in the pressure control valve 56 is kept constant, the center differential becomes free at constant vehicle speed, but as the vehicle speed increases. There is a possibility that it will become directly connected.

Therefore, the control oil pressure of the multi-disc clutch 28 is corrected by a correction oil pressure P□ corresponding to the vehicle speed ■.

Furthermore, as shown in FIG. 15, since the driving force distribution ratio changes in response to the engine torque Te, in this control, the driving force distribution ratio is controlled to a required parking power distribution ratio in response to the engine torque Te. The oil pressure P2 is determined by calculation or based on a map stored in advance, and the required control is performed based on this oil pressure P2.

Furthermore, as shown in FIG. 16, the control hydraulic pressure is adjusted to correspond to the hydraulic pressure P□ in order to avoid the tight corner braking phenomenon, corresponding to the rotation angle of the steering wheel 32 from the neutral position, that is, the steering wheel angle θH. Make a correction by subtracting the amount.

The hydraulic pressure P2 required to obtain the required power distribution ratio corresponding to the engine torque also changes depending on the state of the gear, so based on the characteristics shown in Fig. 17, the hydraulic pressure P2 is adjusted to correspond to each gear. Obtain oil pressure P2 and use it as the basis of control oil pressure.

Regarding this control, the processing within the controller 48 will be explained. As shown in FIG. from,
The throttle opening degree is input to the controller 48 from the throttle sensor 38, the engine speed Ne from the engine speed sensor 104, and the gear position i5 from the gear position sensor 130 (step el).

Next, it is determined whether or not it is normal driving in which no other control law is detected (step e2), and steps e3 to e are performed.
At step 6, the control oil pressure in the multi-disc clutch 28 is calculated.

That is, in step e3, the corrected hydraulic pressure P corresponding to the vehicle speed V is determined. In step e4, engine torque T
Corresponding to the gear position e and the gear stage i5, a hydraulic pressure P2 is determined so as to obtain a driving force distribution ratio of 4:6 as shown by the dashed line in FIG. In step e5, a correction oil pressure P3 for avoiding tight corner braking is determined in accordance with the steering wheel angle θH.

In step e6, from these calculation results, the control oil pressure P to be applied to the multi-disc clutch 28 is 5P=Fs-P, +P
2-P.

It is determined by

Here, Fs indicates return spring force.

Duty D for generating control oil pressure P
is determined from the relationship such as D=f (P) (step e7), and a control signal corresponding to this duty is applied to the pressure control valve 56 (step e8).

As a result, the multi-disc clutch 28 enters the required intermediate engagement state, and normal driving is performed at a driving force distribution ratio (in this example, a ratio of 1 m4 of front wheels to rear wheels 6) that is convenient for the driver.

At this time, the vehicle speed ■ and the engine torque Te.

Even if the gear position IS changes, the control oil pressure P is automatically adjusted, and tight corner braking is avoided even if the steering wheel 32 is rapidly rotated.

By the way, the above-mentioned controls (1) to (7) are executed in an integrated state by the controller 48 in the order of their numbers.

That is, as shown in FIG. 11, in the controller 48, the corresponding RAM is cleared and set as an initial setting (step S1), and then a sampling loop is performed every 15 m5 (step S2).

This sampling loop consists of an input specification A1, a calculation specification A2 performed based on the input specification, and an output specification A3 performed based on the result of the calculation specification.

For input specification A1, wheel speed input J1, steering wheel angle input ■
2, G sensor input 3, other inputs 14, etc. are performed.

In calculation specification A2, data calculation c1, detection processing C2, cancellation C3, and determination processing C4 are sequentially performed, and further, operation specification C5 is performed.

Regarding the data calculation C1, each calculation described on the right side of the figure is performed. Regarding operation specification C5, calculation of oil pressure (SC2,) for center differential control and engine output (
ENG output) is calculated.

In the output specification A3, based on the division result in the operation specification C5, the sub-throttle valve 103 is driven to adjust the engine output (ENG output), and the hydraulic pressure (SQL) of the hydraulic multi-disc clutch for center differential control is controlled. Drive is performed by.

By the way, in the detection process C2, as shown in FIG. 12, it is examined in order whether the input data and the calculated data match each of the control conditions of brake ON control C21 to longitudinal slip control C26, and a match is detected. At times, the flags KENI to KEN6 of the corresponding controls become "1", and when no detection is performed, the state of rQJ continues.

In addition, the release process C3 includes release conditions related to each control from brake ON control C3 to longitudinal slip control C36.
It is examined in order whether the human data and the calculated data match, and when a match is detected, the cancellation flag KAI~KAI6 of each corresponding control becomes "1", and when it is not detected, the rQJ of AI6 is set to KAT1~. The state continues.

Next, the determination process C4 is shown in FIG. 13(a).

It is carried out according to the flow shown in (b), and KEN1 to K
A control flag HAN indicating the type of control to be performed is determined to be one of 1 to 7 based on the values of EN6 and KAII to KAI6.

In addition, flag HAN takes any one of 1 to 7, and each numerical value 1 to 7 of flag HAN corresponds to control (1) to (7), respectively.
(corresponds to steps D1 to D7 in the figure).

Thereby, each control (1) to (7) is performed based on the value of each flag HAN, as shown in FIG. 12.

By the way, in FIGS. 13(a) and 13(b), in step B1, if the previous flag HAN was 1,
The flow for determining the current control type (flag HAN type) is described, and other (7) steps B2 to B7 are similar to those in the case where the previous flag HAN was 2 to 7 control. It is stated.

In this way, in each step B1 to B7, the current flag HAN is changed from the previous flag HAN to HAN=1 to B7.
7.

Therefore, if a situation in which a certain type of control is required continues, control divided into 15 m5 segments is continued multiple times, and if a different situation occurs, the control type is changed using the 15 m5 segment as a switching time.

By controlling with such a system.

Various controls for HAN=1 to 7 are performed with priority given to the smaller number.

As a result, various controls have a hierarchical structure, and interference between controls is prevented.

[Effects of the Invention] As detailed above, according to the four-wheel drive vehicle of the present invention, in a 4Ilii+11 drive vehicle that drives the vehicle by transmitting the output torque of the engine to the front wheels and rear wheels, the output torque is a differential device that distributes torque between the front wheels and the rear wheels;
A driving force distribution control means attached to the differential device and capable of changing the state of torque distribution between the front wheels and the rear wheels by restricting the differential, and a shift lever of an automatic transmission installed in the automobile. - a shift range detection means for detecting the operating position of the engine, and a throttle opening detection means for detecting the opening of the throttle valve of the engine, and detecting information from the shift range detection means and the throttle opening detection means. When it is detected that the shift range is in the low speed range and the throttle opening is in the kickdown range, a drive control signal is output to the drive force distribution control means to directly connect the differential gear. With a simple configuration that requires no controller, when the driver desires a large amount of driving force, the differential gear is directly connected, ensuring that large driving force is transmitted to the road surface in a directly connected 4-wheel drive state. This will improve the driving performance of cars.

[Brief explanation of the drawing]

1 to 17 show a four-wheel drive vehicle as an embodiment of the present invention, FIG. 1 is a basic block diagram of a control system showing its configuration in accordance with the content of the claims, and FIG. is its overall configuration diagram, and Figure 3 is an explanatory diagram showing the configuration of its hydraulic system.
FIG. 4 is a block diagram showing the relationship between each control state, and FIG.
The figures are graphs 6 to 13 to explain the operating effects.
Each figure is a problem analysis diagram (PAD) for explaining the operation of the control system, and each of FIGS. 14 to 17 is a graph for explaining the operation. 2-engine, 4-torque converter, 6-automatic transmission, 8-output shaft, 10-intermediate gear, 2--planetary gear type differential device as differential device, 12a--sun gear, 12b
・-Planetary gear, 12c...Ring gear, ],
2 d--carrier, 14-differential gear device, 15-bevel gear mechanism, 16-front wheel, 17L. 17 R-axle, 18-front wheel, 20-propeller shaft, 21-bevel gear mechanism, 22-differential gear device,
24-rear wheel, 25L, 25R-axle, 28-hydraulic multi-plate clutch, 30--steering sensor, 32-- steering wheel, 34a, 34b-lateral acceleration sensor, 38-throttle sensor, 39-engine key switch, 40,4
2, 44, 46 - wheel speed sensor, 48 - controller, 50 - anti-lock brake device, 50A - brake switch, 50 B - brake (braking means), 51
・-brake pedal, 52-warning light, 54-hydraulic source, 5
6-Pressure control valve system (pressure control valve), 58...-pump,
6゜--Check valve, 62--Pressure control valve, 64-
Relief valve, 66-Accumulator, 68-Pressure switch, 1.01-Traction control system as engine output control means, 102-Main slot 1
- throttle valve (accelerator pedal-based engine output adjustment device as an artificial engine output adjustment device), 103 - auxiliary throttle valve, 104 - engine rotation speed sensor, 105 - engine load sensor, 11.0 - shift range detection means Shift lever position sensor, 110A-:/7 lever, 1.30-gear position sensor, A-driving force distribution control (
center differential control), B = engine power control, engine output control). Fig. 3 Fig. 7 Section 14 Fig. 15 Fig. 16 Fig. Ha/Yru Mountain H Fig. 17 Engine Torque Te

Claims (1)

[Claims] In a four-wheel drive vehicle that drives the vehicle by transmitting engine output torque to the front wheels and rear wheels, a differential device that distributes the output torque between the front wheels and the rear wheels, and a differential device attached to the differential device are provided. a driving force distribution control means capable of changing the state of torque distribution between the front wheels and the rear wheels by restricting the differential; and detecting the operation position of a shift lever of an automatic transmission installed in the automobile. and a throttle opening detecting means for detecting the opening of a throttle valve of the engine, and detecting information from the shift range detecting means and the throttle opening detecting means to determine the shift range. A controller is provided that outputs a drive control signal to the drive force distribution control means to directly connect the differential gear when it is detected that the throttle opening is in the kickdown range and the throttle opening is in the low speed range. A four-wheel drive vehicle that is characterized by