JP3015833B2 - Vehicle control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a traction control for controlling a torque applied to a drive wheel to prevent an excessive slip of the drive wheel on a road surface. The present invention relates to a control device for a vehicle provided with means.

[Conventional technology]

Conventionally, in order to prevent excessive slip of the drive wheel when traveling on a slippery road such as a snowy road or at the time of cornering, for example, as shown in JP-A-57-22948, There is known a traction control means for controlling a brake or a throttle valve of an engine to reduce the torque applied to the drive wheels when the occurrence of the traction occurs.

Further, in order to improve the running stability and steering response of the vehicle, for example, as shown in Japanese Utility Model Laid-Open Publication No. 56-147107, the suspension characteristics of a suspension mechanism that supports the weight of the vehicle according to the running state of the vehicle are disclosed. Or, as disclosed in Japanese Patent Application Laid-Open No. 55-55059, the steering characteristics of a steering mechanism for steering a vehicle are changed.

[Problems to be solved by the invention]

In order to properly carry out the traveling control of the vehicle by the suspension mechanism and the steering mechanism, it is desirable to operate these mechanisms in cooperation with traction control means for suppressing the slip of the drive wheels. The means operates both when traveling on slippery roads such as snowy roads, and when performing extreme driving at the time of starting and cornering, etc., so-called sports driving, which clearly differ from each other in the running condition of the vehicle. Therefore, there is a problem that the suspension mechanism and the steering mechanism cannot be controlled simply in conjunction with the operation state of the traction control.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can operate a traction control unit and a steering mechanism in proper cooperation with each other, and can control the steering mechanism according to a driving state of a vehicle. It is an object of the present invention to provide a control device for a vehicle capable of executing the following.

[Means for solving the problem]

The present invention includes traction control means for controlling the applied torque to the drive wheels to prevent the slip of the drive wheels on the road surface from becoming excessive, and a steering mechanism capable of changing the steering characteristics. In the vehicle, a road surface state detecting means for detecting a state of slipperiness of the road surface, a running state determining means for determining a running state of the vehicle according to signals output from the traction control means and the road surface state detecting means, Steering characteristic control for changing the steering characteristics of the steering mechanism in a direction to weaken the assist force at the time of steering when the traction control unit determines that the vehicle is traveling on a slippery road surface when the traction control unit operates. Means.

[Action]

With the above configuration, in the present invention, according to signals output from the traction control unit and the road surface condition detection unit,
When the traveling state determination unit confirms that the vehicle is traveling on a slippery road surface when the traction control unit is operated, it is determined that the vehicle is in a sports traveling state.
The steering characteristic of the steering mechanism is changed to a state suitable for the sport running state.

〔Example〕

FIG. 1 shows a control device for a vehicle according to one embodiment of the present invention. The vehicle has rear wheels 2L, 2L driven by an engine 1.
R and front wheels 3L and 3R to be driven wheels. The driving force generated in the engine 1 is transmitted to the rear wheels 2L, 2R via the clutch 4, the transmission 5, the propeller shaft 6, the differential gear 7, and the axle shafts 8, 9.
To rotate the rear wheels 2L and 2R.

Each of the wheels 2L, 2R, 3L, 3R has a rotational speed sensor 10a to
d are provided, and detection signals of the rotational speed sensors 10 a to 10 d are input to the traction control unit 11. Then, in the traction control means 11, the slip ratio of the rear wheels 2L, 2R, which are driving wheels, is calculated from the difference in rotation speed between the front wheels 3L, 3R and the rear wheels 2L, 2R, and the calculated value of the slip ratio is set in advance. A control signal is output from the traction control means 11 to the throttle valve 12 and the rear wheel brakes 13a and 13b of the engine 1 so that the target slip ratio is obtained. That is, in order to prevent the rear wheels 2L, 2R from being excessively slipped on the road surface, when it is confirmed that the slip ratio of the rear wheels 2L, 2R is equal to or more than a predetermined value in the traction control unit 11, The throttle valve 12 and the rear wheel brakes 13a to 13b are feedback-controlled in accordance with a control signal output from the traction control unit 11, whereby the torque applied to the rear wheels 2L and 2R is controlled. .

Further, the detection signals of the rotation speed sensors 10a to 10d are
The condition is input to a road surface condition detecting means 14 for detecting the condition of slipperiness of the road surface, so-called road surface μ. This road surface condition detecting means 14
For example, at the time of operation of the traction control means 11, the rear wheels 2L, 2R and the rear wheels 2L, 2R, which are driving wheels, have a preset target slip ratio from the difference in rotation speed between the rear wheels 2L, 2R and the front wheels 3L, 3R. After confirming that the vehicle is in the maximum grip state, at this time, the acceleration of the vehicle body is calculated based on the change in the rotational speed of the front wheels 3L and 3R, which are driven wheels, and the road surface μ is calculated in accordance with the acceleration.
Is to be detected. That is, when the rear wheels 2L and 2R are in the maximum grip state, the acceleration of the vehicle
, The road surface μ is read out by the road surface condition detecting means 14 according to the acceleration of the vehicle body in the maximum grip state, and the condition of slipperiness of the road surface is detected. .

An output signal indicating the operation state is input from the traction control unit 11 to a traveling state determination unit 15 that determines the traveling state of the vehicle, and a detection signal from the road surface state detection unit 14 is input to the traveling state determination unit 15. Is done. The running state determination means 15 determines whether the vehicle has a high μ when the traction control means 11 is operated in accordance with the output signal and the detection signal.
By determining whether or not the vehicle is in a road running state, it is determined whether or not the vehicle is in a sports running state in which severe driving is required, and it has been confirmed that the vehicle is in this sports running state. In this case, the suspension characteristic control means 16 of the suspension mechanism 17 and the steering mechanism 19
The control signal is output to the steering characteristic control means 18.

The suspension mechanism 17 is, as shown in FIG.
A shock absorber 22 comprising a spring 20 and an oleo damper 21 is provided. An air spring 23 comprising a diaphragm made of an elastic member is provided around the oleo damper 21. An orifice is provided on the piston of the shock absorber 22, and a plunger rotationally driven by a solenoid 25 is provided in a piston rod 24 to change the diameter of the orifice. When the solenoid 25 is excited according to a control signal output from the suspension characteristic control means 16, the plunger rotates to reduce the diameter of the orifice, the damping force is increased, and the suspension characteristic of the suspension mechanism 17 is hardened. It is configured to be switched to the side.

Further, the air spring 23 is connected to a control air chamber 27 by an air pipe 26, and the air spring 23 and the control air chamber 27 are connected to each other in accordance with the operation of a solenoid valve 28 provided at an inlet of the control air chamber 27. The communication state is controlled. That is, when the solenoid of the solenoid valve 28 is excited in response to a control signal output from the suspension control means 16 to the suspension mechanism 17 of each wheel, the communication state between the air spring 23 and the control air chamber 27 is cut off, As a result, the effective volume of the chamber of the air spring 23 decreases, and the spring constant increases.
Is configured such that the suspension characteristics can be switched to the hard side.

As shown in FIG. 3, the steering mechanism 19 has a steering handle 28 and a steering shaft 29 that is rotationally driven by the steering handle 28.
A pinion shaft 31 having a steering pinion 30 is provided at its tip. The above steering pinion 30
Is engaged with a rack 33 on a steering rack shaft 32, and the steering rack shaft 32 moves left and right in accordance with the rotation of the steering pinion 30, and the knuckle arms 34, 35
The steering force is transmitted to the front wheels 3L, 3R through the steering wheel.

The steering mechanism 19 is provided with a hydraulically operated power assist device 36 for assisting the steering force. The power assist device 36 has a control valve 37 provided on a pinion shaft 31 and a power cylinder 38 provided on a steering rack shaft 32, and an oil pump for supplying hydraulic pressure to the power cylinder 38. 39
Is connected to the engine 1. After the pressure oil supplied from the oil pump 39 passes through the hydraulic supply passage 40 and is introduced into the control valve 37, the hydraulic oil is supplied to one of the hydraulic chambers 43 and 44 in the power cylinder 38 through the hydraulic passages 41 and 42. Guided to one side, the piston 45 is moved to assist the steering force. At the time of this assist, the hydraulic passage to which the pressure oil is not supplied communicates with the hydraulic return passage 46 to return the hydraulic oil in the cylinder 38 to the pump 39.

The hydraulic return passage 46 has a pump
A solenoid valve 47 for adjusting the amount of oil returned to 39 is provided. The hydraulic pressure supply passage 40 is provided with a bypass passage 48 communicating with the solenoid valve 47. When a control signal is output from the steering characteristic control means 18 to the solenoid valve 47, the plunger 49 of the solenoid valve 47 moves in the direction of the arrow, and the amount of oil introduced into the bypass passage 48 from the hydraulic pressure supply pipe 40. Is increased, the assist force of the power assist device 36 is weakened.

A control operation for switching the suspension characteristics of the suspension mechanism 17 in the above configuration will be described with reference to a flowchart shown in FIG. When the control operation starts, first, in step S1, signals output from the respective rotation speed sensors 10a to 10d are read into the control device, and then, in step S2, the slip ratio of the rear wheels 2L, 2R is equal to or more than a predetermined value. It is determined whether or not the traction control is being executed. If it is confirmed in step S2 that the traction control means 11 is operated to execute traction control, it is determined in step S3 whether or not the vehicle is traveling on a high μ road. That is,
The road surface μ is read by the road surface condition detecting means 14 based on the acceleration of the vehicle at the time when it is confirmed that the predetermined slip ratio such as the rear wheels 2L and 2R are in the maximum grip state is obtained. The traveling state determination means 15 determines whether or not the vehicle is higher than a preset reference value, thereby confirming whether or not the vehicle is traveling on a high μ road.

In addition, as a result of the above determination, when it is confirmed that the vehicle is in a high μ road running state when the traction control unit 11 is operated, and the vehicle is in a sports running state such as suddenly starting or turning sharply on a mountain road or the like, In step S4, a flag indicating that the vehicle is in a sport running state is set to 1, and in step S5, a control signal is output from the running state determining means 15 to the suspension characteristic controlling means 16 to cause the suspension mechanism 17 to perform suspension. Control is performed to switch the characteristics to the hardware side.

In step S2, the traction control means 11 is not operating, or in step S3, the vehicle
If it is confirmed that the vehicle is not running on the road,
Whether or not the above flag is set to 1 in S6,
That is, it is determined whether or not the suspension characteristic has been switched to the hard side in accordance with the current sport running state. As a result of this determination, if it is confirmed that the flag has been set to 1, the timer is set in step S7, and the flag is reset to 0 in step S8. It is determined whether or not a set predetermined time (about 5 seconds) has elapsed. Until the timer expires, the suspension characteristics are maintained on the hard side in step S5, and when it is confirmed that the time has elapsed, control is performed such that the steering characteristics of the suspension mechanism 17 are switched to the software side in step S10. I do.

In this way, according to the signals output from the traction control means 11 and the road surface condition detection means 14, the traveling state determination means 15 determines whether or not the vehicle is in a high μ road traveling state when the traction control means 11 is operated. As a result, it is possible to accurately determine the traveling state of the vehicle that causes the traction control for preventing the rear wheels 2L and 2R from excessively slipping. That is, traction control is executed because the vehicle is in a sports running state that requires severe driving of the vehicle when traveling on a high μ road, or traction control is executed because the vehicle is traveling on a low μ road such as a snowy road. Can be accurately determined.

If the result of the determination by the traveling state determination means 15 indicates that the vehicle is traveling on a low μ road and is in a non-sports traveling state, the suspension characteristic is switched by the suspension characteristic control means 16. Instead, the suspension characteristics are switched to the hard side when it is confirmed that the vehicle is in a sports running state, thereby effectively preventing rolling or pitching of the vehicle body due to extreme driving, and driving stability Performance can be improved.

Further, in the above embodiment, a timer is set when the sports running state of the vehicle is released, and the suspension characteristics are set to the soft side when the non-sports running state is continued until the timer expires. For example, when the vehicle is traveling on a mountain road or the like, the traveling state of the vehicle is frequently switched, and when the traction control is performed intermittently, the suspension characteristics are frequently changed. There is an advantage that an excessive change in the operating characteristics due to switching to the above can be prevented.

In the above embodiment, the road surface condition is detected in accordance with the acceleration of the vehicle body. However, the presence or absence of rain, snow or ice burn is detected, or the operation state of the manual input means is detected. For example, the road surface condition may be determined. In addition, the suspension characteristics of the suspension mechanism 17 do not necessarily need to be configured so that all four wheels can be switched.
Only the suspension characteristics of 2L and 2R may be switched. In this case, by switching the suspension characteristics to the hard side, the tendency of the vehicle to understeer is weakened, the steering response is improved, and the driving characteristics suitable for the sport running state of the vehicle can be obtained.

Next, a control operation for changing the steering characteristics of the steering mechanism 19 will be described with reference to a flowchart shown in FIG. Steps S1 to S9 are configured similarly to the control operation of the suspension mechanism 16.
If it is determined in steps S1 to S3 that the vehicle is in the sport running state, and if the flag indicating this is set to 1 in step S4, step S1
In 1, a control signal is output from the traveling state determination means 15 to the steering characteristic control means 18 to
The steering mechanism is controlled to reduce the assist force of the steering mechanism so that a large steering force is required when turning.
Change the 19 steering characteristics. As a result, the steering wheel 28 is prevented from being excessively turned, so that a steering feeling suitable for the sport running state is obtained, and the running stability is improved.

When it is confirmed in step S9 that the non-sports running state of the vehicle has continued for a predetermined time, step S1 is executed.
The process proceeds to 2, and the assist force of the power assist device 36 is returned to the original state.

Note that, instead of the steering mechanism 19 having the power assist device 36, a steering mechanism having a gear device configured to be able to change the gear ratio is provided, and the traveling state determination unit 15 may determine that the vehicle is in a sports traveling state. When it is confirmed, the gear device may be switched to reduce the steering gear ratio. In this case, a large steering force is required at the time of turning, so that the steering wheel 28 can be prevented from being excessively turned, and even when the steering wheel 28 is slightly operated, the steering angles of the front wheels 3L and 3R greatly change. There is an advantage that a proper steering can be performed.

Further, when the front wheels 3L, 3R are steered, in a vehicle equipped with a rear wheel steering device that steers the rear wheels 2L, 2R based on a preset steering ratio characteristic, the vehicle is in the sport running state. Is confirmed, the turning ratio of the rear wheels 2L and 2R based on the turning ratio characteristic I indicated by the solid line in FIG. 6 is changed from the turning control state of the rear wheels 2L and 2R to the opposite phase side as indicated by the broken line. The steering responsiveness may be improved by shifting to the steering control state of the rear wheels 2L, 2R based on the corrected steering ratio characteristic II that is deviated.

When the traveling state determination unit 15 confirms that the vehicle is in a sports traveling state, the suspension characteristic switching by the suspension characteristic control unit 16 and the change of the steering characteristic by the steering characteristic control unit 18 are performed simultaneously. It may be configured as follows. In this case, the characteristic control by the suspension characteristic control means 16 and the characteristic control by the steering characteristic control means 18 and the traction control by the traction control means 11 are appropriately executed in cooperation with each other, so that the suspension characteristic and the steering characteristic adapted to the sport running state are adjusted. Properties can be obtained.

〔The invention's effect〕

As described above, the present invention relates to a vehicle in which the steering characteristics can be changed, when it is confirmed that the vehicle is traveling on a slippery road surface when the traction control unit is operated by the traveling state determination unit, By changing the steering characteristic of the steering mechanism in a direction to weaken the assist force at the time of steering,
There is an advantage that a steering feeling and a steering response suitable for a sport running state are obtained, and the running stability of the vehicle is improved.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing an embodiment of a vehicle control device according to the present invention, FIG. 2 is a schematic diagram showing a specific example of a suspension mechanism, FIG. 3 is a schematic diagram showing a specific example of a steering mechanism, 4 is a flowchart showing a control operation of the suspension mechanism, FIG. 5 is a flowchart showing a control operation of the steering mechanism, and FIG. 6 is a characteristic diagram showing a steering ratio characteristic of a rear wheel in a rear wheel steering device. 2L, 2R: rear wheels (drive wheels), 11: traction control means, 14: road surface condition detection means, 15: running state determination means, 16: suspension characteristic control means, 17: suspension mechanism, 18 …… Steering characteristic control means, 19…
... steering mechanism.

Claims (1)

(57) [Claims] 1. A traction control means for controlling a torque applied to a driving wheel to prevent an excessive slip of the driving wheel on a road surface, and a steering mechanism capable of changing a steering characteristic. In the vehicle, a road surface state detecting means for detecting a state of slipperiness of the road surface, a running state determining means for determining a running state of the vehicle according to a signal output from the traction control means and the road surface state detecting means, A steering characteristic for changing a steering characteristic of the steering mechanism in a direction to weaken an assist force at the time of steering when it is confirmed by the traveling state determination means that the vehicle is traveling on a slippery road surface when the traction control means is operated. A control device for a vehicle, comprising: a control unit.