JPH042528A - Four wheel drive automobile - Google Patents

Abstract

PURPOSE:To avoid the interference of control with each other by allowing at first control by a driving force distribution control means when a required running condition is detected and, if such control is insufficient to improve the driving condition of a vehicle, allowing engine output control by an engine output control means. CONSTITUTION:A driving force distribution control means 28 such as a multiplate clutch which can control the distribution of engine output torque to front wheels and rear wheels, a human-initiated engine output adjusting device 102 such as a throttle valve which serves for human-initiated adjustment of engine output, and an engine output control means 101 which can control engine output independently of the output adjusting device 102 are provided. When a required running or driving condition is detected in accordance with information from a vehicle condition detecting means, preset signals are output from a controller 48 to the driving force distribution control means 28 in order to improve the running condition of the vehicle. Also, if the control by the driving force distribution control means 28 is insufficient to improve the running condition of the vehicle, preset control signals are output to the engine output control means 101.

Description

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

[Prior Art] In a four-wheel drive vehicle, a driving force 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 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.

On the other hand, apart from such a driving force transmission device, control for wheel slipping has also been considered, but this control for wheel slipping is generally performed independently of the above-mentioned driving force transmission control.

[Problems to be Solved by the Invention] However, in the conventional driving force transmission device as described above, control of the center differential and control of wheel slipping in various normal controls are independent of each other, so they are not compatible with each other. There is a risk of interference, and there is a problem that good control results cannot be obtained.

The present invention was devised in view of the above-mentioned problems, and aims to provide a four-wheel drive vehicle that avoids interference between various controls and can obtain reliable and stable control results. .

[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. an artificial engine output adjustment device that artificially adjusts the output of the engine; and an artificial engine output adjustment device that is separate and independent from the artificial engine output adjustment device. and an engine output control means capable of controlling the output of the engine, and a vehicle state detection means for detecting the running state and driving state of the vehicle, and a vehicle state detection means that detects a required running state based on information from the vehicle state detection means. Alternatively, when the driving condition is detected, a predetermined control signal is output to the driving force distribution control means in order to improve the driving condition of the vehicle, and the driving force distribution control means controls the driving force distribution control means in accordance with the control signal to improve the driving condition of the vehicle. The present invention is characterized in that a controller is provided which outputs a predetermined control signal to the engine output control means when the improvement is insufficient.

[Function] In the four-wheel drive vehicle of the present invention described above, when a required running state or driving state to be controlled is detected, first,
Control is performed by the driving force distribution control means, and when the driving force distribution control is insufficient to improve the driving state of the vehicle, the engine output control means performs engine output control.

[Example 7] 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 is ee r
tt is also a problem analysis diagram to explain the operation of the control system,
14 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 10 to a planetary gear type differential device 12, which serves as an actuating device that distributes engine torque between front wheels and rear wheels as required.

The output of this planetary gear type differential wave [12] is transmitted on the one hand by the reduction gear mechanism 19. The transmission is transmitted from the axles 17 7, 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. The left and right rear wheels 24.
26. The planetary gear type differential device 1-2 includes a sun gear 12a and a sun gear 12a, similar to the conventionally known one.
planetary gear disposed on the outside of the planetary gear 12b], and a ring gear 1 disposed on the outside of the planetary gear 12b.
2c, the output of the output shaft 8 of the automatic transmission 6 is input to the carrier 12d supporting the planetary gear 12b,
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, and the ring gear 12c is interlocked with the propeller shaft 20 via the rear wheel output shaft 29 and the bevel gear mechanism 15. ing.

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. Till.

That is, the hydraulic multi-disc clutch 28 is connected to the sun gear 12a (
or ring gear 12c) and carrier] 2d, and the frictional force changes depending on the pressure applied to its own hydraulic chamber.
C) and the carrier 1.2d is restrained.

Therefore, the planetary gear type differential device 12 appropriately controls the hydraulic multi-disc clutch 28 from a completely free state to a locked state, thereby transmitting torque to the front wheel side and the rear wheel side. The axis is about 33:67 to 50:
It can be controlled between 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 at the set pressure (9 kg/ci), the hydraulic multi-disc clutch 28 is in the locked state, and the differential restriction is substantially zero. Then, the ratio of front wheels to rear wheels becomes 50:50, resulting in a direct connection.

Further, reference numeral 30 denotes a steering sensor 34a, 34. b is the lateral acceleration G F acting on the front and rear parts of the vehicle body, respectively.

A lateral acceleration sensor that detects GB; 36 is a longitudinal acceleration sensor that detects acceleration Gx in the longitudinal direction acting on the vehicle body;
8 is a throttle sensor that detects the throttle opening of engine 2, 39 is an engine key switch of engine 2, and 40, 42, 44, and 46 are front left wheel 16, front right wheel 18, rear left wheel 26, and rear right wheel, respectively. 28, and the outputs of these switches and each sensor are input to the controller 48.

Reference numeral 50 is an anti-lock brake device.

This anti-lock brake device 150 operates in conjunction with the brake switch 50A. That is, when the brake switch 50A is turned on when the brake pedal 5 is depressed, an anti-lock brake activation signal is output in conjunction with this, and the 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. Also, 52 is Con1
~This is a warning light that lights up based on the control signal for the roller 48.

Note that the controller 48 includes a CPU, ROM, RAM, interface, etc., which are not shown but are necessary for control 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 where the hydraulic chambers 8 and the pump 58 are communicated, and a second position where the hydraulic chambers 2 and the reservoir of the automatic transmission 6 are communicated.

A relief valve 64 is provided in the passage between the check valve 60 and the pressure control valve 62 and opens at a set pressure (9 kgldi) to release oil to the reservoir of the automatic transmission 6. A switch 68 is 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 1-roller 48.

Next, the traction control system 101- as an engine output control means will be explained 6. 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. 112 and the connecting means, etc., constitute an accelerator pedal system engine output adjustment device (artificial engine output adjustment device). A sub-throttle valve 103 as engine output control means that is controlled independently of the accelerator pedal-based engine output adjustment device is provided in series with the main throttle valve 102 in the intake passage of the engine 2. This sub-throttle valve 103 is driven by a motor.

The motor has rear wheel speed sensors 44, 46 and front wheel speed sensors 40.4.
2. The drive is controlled based on the detection results of the engine rotation speed sensor 104, engine load sensor 105, etc.

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 control for restraining the differential of the planetary gear type differential device 12 by the hydraulic multi-disc clutch 28 is hereinafter referred to as power distribution control (
or center differential control) A.

Next, the operation of the controller 48, that is, the controller 48 is activated.
8], the plotter diagram and problem analysis diagram (P A D ; Problem An
lysis diagram).

By the way, the above-mentioned center differential control A and engine output control B are such that center differential control A is first performed, and when 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 (
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 opening state obtained by the center differential control A is insufficient (step a6), and the center differential control A is determined according to each control type described later. If the control alone is insufficient, engine output control B is performed (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 sensors 44, 46 and the front wheel speed sensors 40, 42 read the difference in rotational speed between the front and rear wheels. The operating state of the engine 2 is detected and calculated by the engine rotation speed sensor 104 and the engine load sensor] 05, and the motor is operated in accordance with the calculation result, and the sub-throttle valve 10 is activated.
3 in the closing direction.

This controls the amount of air flowing into the engine to suppress the rotational torque of the carrot and prevent 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 one curve with center differential free, curve L4 is with center differential control A, and curve L4 is the one with 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) indicates a region where wheel slipping is suppressed by engine output side #B.

In this way, by operating the engine output control B after the center differential control A and combining it with the surface control,
For example, in less than - seconds after control is started, 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 nine control performed in this embodiment is described in its priority order as follows: brake ON control [control (1)], high speed driving control [control (2)], [power increase control [control (3)],
Spin control [control (4)], drift control [control (5)]
], longitudinal slip control control (6)], 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.

(]-) Brake switches 11 and 2 As shown in FIG. An anti-lock brake device 50 is provided as a brake restriction device.

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 51 is not depressed, but when the brake pedal 51 is depressed and the brake switch 50A is in the OFF state. As soon as the controller 4 turns on,
8 outputs an operation stop signal, that is, a hydraulic pressure supply stop signal, to the multi-disc clutch 28, and 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 bl),
is in the ON state (step b2).
)6 When the brake switch 50A is in the ON state, the brake control flag is set to rlJ (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 "0" (step b6).

Next, it is determined whether the brake control flag is “1” (
After step b7), if the brake control flag is "]", center differential free control (step b8)
As a result, a release signal for disengaging 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 (step b9) is performed to make the traction control system 01 inactive.

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, the center differential free control A and the process of deactivating the traction control system]-01 are performed.

On the other hand, when the brake switch 50A is switched to the OFF state, steps bl, b2. b4. The process proceeds in the order of b5 and b6, and in step b6, the brake control flag is switched to "0".

This creates a center differential free state (step b).
8),) - The traction control off state (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 1 power 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, the driving force distribution control means 12 and 28.

Since the driving force distribution is controlled according to the current driving condition, it is expected that the distribution condition will not be suitable for braking.
Although this is not desirable in terms 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 these output signals are inputted to the controller 48 as the traveling speed data of the automobile.

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 power 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 cannot be controlled to the above-mentioned free state, and the center differential becomes constrained to some extent. .

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
is the predetermined high speed V. 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 reach is: ■ '=:V, -T. X a , and when v>v', the center differential may be set free.

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-V 1-x
) / T (step f2).

Here, Vi is the vehicle speed according to the current sampling, ■□-1 is the vehicle speed according to the previous sampling, and T is the sampling time (1
5ms).

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 Vi>v', the high-speed control flag is set to 1.
(Step f5), and store V' as V'' (Step f6).

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

If the vehicle speed has decreased, ■ will be smaller than the previous V'', so proceed to step f9, and if the vehicle speed has not decreased, ■
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, and if the timer is not set, the timer is set (step flO); 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 "O" (step f12) and the timer is cleared (step fi3).

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 "]-
'', a signal for freeing the center differential (that is, a signal for releasing the engagement of the multi-disc clutch 28) is output (step f16).

Therefore, when the vehicle speed v1 becomes greater than V' during acceleration, the process starts from step f4, steps f5, f6, and so on. f7
．． f8. f14, reset the timer in step f1.4, and then step f15. Proceeding to f16, the center differential is set free at step f16.

Such control continues while the vehicle is accelerating.

In this case, while continuing high-speed running, step f1
4, the timer is cleared and continues to be reset.

Then, when the vehicle speed ■ decreases and ■ 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 "O".

Then, in step fil, 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 "O" (step fil). 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.

This chattering can be prevented by setting the vehicle speed at which the high-speed control flag is set to "1" to be, for example, 1.40 km/h, and the vehicle speed at which the high-speed control flag is returned to "0" to be 1100 km/h.
This may be done by providing a difference between the vehicle speed at which high-speed control is entered and the vehicle speed at which high-speed control is released.

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) Large driving force control As shown in FIG. 2, this embodiment is equipped with a shift lever position sensor 110 as shift range detection means, and a throttle sensor 38 that detects the throttle opening of the engine 2 at 0. are provided, and these detection signals are input to the 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.

By the way, when the driver wants a large driving force while the vehicle is running, it is desirable to drive the vehicle in a state where the four wheels are directly connected, regardless of whether the 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, resulting in a direct four-wheel drive state.

Regarding this control, the processing within the controller 48 will be explained. As shown in FIG. d1), shift lever is L
Whether 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 “1”.
(step d4), and step d5. d6. d
After LO, proceed to step dll and install multi-disc clutch 2.
Direct-coupled 4WD control is performed with 8 fully engaged.

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, traction control (engine output control B), which is control to reduce the driving force, is canceled (step d]2).

On the other hand, if the operating condition changes and the shift range is no longer in L range or 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. Then, each step d7. At c19, set the large driving force control flag to "0"
to return to. In this case, Sten"11/'sll, s1
Since it does not proceed to 2, the direct 4WD state is canceled and the high driving force 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 axis, and the desired power performance is obtained.

(4) Spin control This control is based on the output signal of the shift lever position sensor 110 and the output signal of the steering angle sensor 30 to detect that the shift lever is not in the L range or the R range and that the spin condition is satisfied. It is done on condition.

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 θ1 (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.

In addition, 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 the shift range is not in the R or L range, and the required conditions are satisfied for the lateral acceleration. This will be done on the condition that the

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 in the R, T- 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 1 are changed.
It is canceled when the opening degree matches the opening degree of 03.

(6) Longitudinal slip control This control consists of the output signal of the lever position sensor 110, the throttle sensor 38, and the wheel speed sensor 40.4.2.
Based on the detection signal of 44.46, the shift range is R, L.
This is done when the following conditions are met: the engine is not in the range, the engine is not in an idling state, and the wheels are spinning.

In this control, center differential control A is performed and engine output control mB 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 the conditions that the spin condition is not satisfied and the slip condition is not satisfied, and if either the idle state, the shift range is in the R or L range, or the steering wheel angle θH is large. It will be released when it is satisfied.

(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 P1 in the multi-disc clutch 28 is the first
As shown in the graph of FIG. 4, it has a characteristic of increasing as the vehicle speed V increases, and depending on the vehicle speed V, it may be larger or smaller than the return spring force Fs.

Therefore, when the centrifugal oil pressure l)1 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.

As described above, 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 a constant vehicle speed, but as the vehicle speed increases, the center differential becomes free. 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 driving force 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. 36, the control hydraulic pressure is applied to tie 1 in accordance with the rotation angle of the steering wheel 32 from the neutral position, that is, the steering wheel angle θH, in order to avoid the corner braking phenomenon. A correction is made by subtracting an amount corresponding to the oil pressure P.

Since the oil pressure P2 required to obtain the required driving force distribution ratio corresponding to the engine torque also changes depending on the state of the gear position, the oil pressure P2 corresponding to each gear position is determined based on the characteristics shown in Fig. 17. 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. ,
The throttle opening is input from the throttle sensor 38, the engine speed Ne from the engine speed sensor]-04, and the gear position i5 from the gear position sensor 130, respectively, to the controller 48 (step el).

Next, it is determined whether or not it is normal driving when 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, a corrected oil pressure P□ corresponding to the vehicle speed ■ 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, the control oil pressure P to be applied to the multi-disc clutch 28 is determined from the calculation results of these calculations as P=Fs-P1+P
2-P3.

Here, FS indicates return spring force.

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

As a result, the multi-disc clutch 28 is brought into the required intermediate engagement state, and normal driving is performed in a state where the driving force distribution ratio (in this example, the ratio of the front axle 4 to the rear wheels 6) is suitable for the driver.

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

Even if the gear stage 1s changes, the control oil pressure P is automatically adjusted, and tight corner braking is avoided even if the steering wheel 32 is rotated rapidly.

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.

In the input specification A1, wheel quick entry crab 1, handle bird man crab 2, G sensor input crab 3, other entry crab 4, etc. are performed.

In calculation specification A2, data calculation CI, 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 (SQL) for center differential control and engine output (E
NG output) is calculated.

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

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. Sometimes the flags KENI to KEN6 of the corresponding controls become "1", and when no detection is detected, the "Oj" state continues.

In addition, the release process C3 includes release conditions regarding each control of brake ON control C31 to longitudinal slip control C36.
It is examined in order whether the input data and calculated data match, and when 5 matches are detected, the release flags KA11 to KAI6 of each corresponding control become "1", and when non-detection, the state of KAII to KAI6 is "0". will continue.

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

It is carried out according to the flow shown in (b), KEN]-~
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 KEN6 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 the other steps B2 to B7 are also described in the same way when the previous flag HAN was 2 to 7 control. ing.

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

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, HAN
Various controls for =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 four-wheel drive vehicle that drives the vehicle by transmitting the output torque of the engine to the front wheels and rear wheels, A driving force distribution control means that can control the distribution of output torque between the front wheels and the rear wheels, an artificial engine output adjustment device that artificially adjusts the output of the engine, and a separate device from the artificial engine output adjustment device. and an engine output control means capable of independently controlling the output of the engine, a vehicle state detection means for detecting the traveling state and driving state of the vehicle, and a necessary When the running condition or driving condition is detected, a predetermined control signal is output to the driving force distribution control means to improve the running condition of the vehicle, and the driving force distribution control means controls the vehicle according to the control signal. The simple configuration includes a controller that outputs a predetermined control signal to the engine output control means when the condition is insufficiently improved. First, driving force distribution control is performed, and if this driving force distribution control is sufficient, Since engine output control is performed when a suitable control effect cannot be obtained, interference between driving force distribution control and engine output control is avoided, and the advantage is that the desired vehicle driving state can be reliably and stably obtained. be.

[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, 12--planetary gear type differential device as differential device, 12a sun gear, 12b-planetary gear, 12c -Ring gear, 12 d-Carrier, 14...-Differential gear device, 15-...Bevel gear mechanism, 16-...Front wheel, 17L. 17R.--Axle,]-8.--Front wheel, 20-.-Propeller shaft, 21-.Bevel gear mechanism, 22-.Differential gear device, 24.--Rear wheel, 25L, 25R.--Axle, 2.
8...-Hydraulic multi-plate clutch, 30-Steering sensor, 32-
- Steering wheel, 34a, 34b - Lateral acceleration sensor, 38 - Throttle sensor, 39 - Engine key switch, 40, 42.44.46 - Wheel speed sensor, 48 - Controller, 50 - Anti-lock Brake device, 50A--Brake switch, 50B-
Brake (braking means), 51-brake pedal, 52-
・・Warning light, 54-Hydraulic pressure source, 56-Pressure control valve system (pressure control valve), 58-Pump, 60-・Check valve, 62
- Pressure control valve, 64 - Relief valve, 66 - Accumulator, 68 - Pressure switch, 101 - Traction control system as engine output control means, 102 - 4 Throttle valve (artificial engine output adjustment device) accelerator pedal system engine output adjustment device), 103--auxiliary throttle valve, 104--engine rotation speed sensor, 105--engine load sensor, 11
0...-shift lever position sensor as shift range detection means, 1.1OA-shift lever 1130-gear position sensor, A-1 power distribution control (center differential control), B
-4 Power control (engine output control). Figure 1

Claims (1)

[Claims] In a four-wheel drive vehicle that drives a vehicle by transmitting output torque of an engine to front wheels and rear wheels, a driving force distribution control means capable of controlling the distribution of the output torque between the front wheels and the rear wheels; an artificial engine output adjustment device that artificially adjusts the output of the engine; and an engine output control means that can control the output of the engine separately and independently from the artificial engine output adjustment device; a vehicle state detection means for detecting the vehicle state and driving state, and when a required running state or driving state is detected based on information from the vehicle state detection means, the driving force distribution control is performed to improve the running state of the vehicle. a controller that outputs a predetermined control signal to the engine output control means, and outputs a predetermined control signal to the engine output control means when the driving condition of the vehicle is insufficiently improved by the control by the driving force distribution control means according to the control; A four-wheel drive vehicle characterized by being equipped with.