JPH11263112A - Control device of suspension mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damping force of a hydraulic shock absorber from becoming excessively large to cause locking of a vehicle wheel by adding a correction depending upon the external air temp. to the control of the damping force of the hydraulic shock absorber. SOLUTION: In this control device a suspension mechanism to be controlled is equipped with a hydraulic shock absorber A having variable damping force, a sensor to sense the vehicle running condition and operating condition, and an optimum damping force calculating means to calculate the optimum value of the damping force the shock absorber A in accordance with the output of the sensor. This control device controls the damping force of the shock absorber A so that it becomes the optimum value determined by the optimum damping force calculating means. The vehicle is further equipped with an external air temp. sensor 27 to sense the external temp., and the value obtained is used to correct the optimum value of the shock absorber A in accordance with the external air temp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a suspension mechanism of a vehicle, which adjusts a damping force of a hydraulic shock absorber in accordance with an outside air temperature in addition to a running state and an operating state of the vehicle.

[0002]

2. Description of the Related Art A conventional active suspension mechanism detects a running / driving state of a vehicle such as a steering angle, a steering speed, a vehicle speed, a lateral acceleration and the like, and based on the running / driving state of a vehicle, a damping force of a hydraulic shock absorber is determined. Controlled optimally. Specifically, during normal running, the damping force of the hydraulic shock absorber is reduced to improve ride comfort. For example, when the vehicle posture becomes unstable, such as when the lateral acceleration acting on the vehicle is large and the vehicle tilts sideways, In this case, the damping force of the hydraulic shock absorber is increased in order to suppress the posture change. However, the above-mentioned suspension mechanism does not perform control that takes into account the friction coefficient (μ) of the road surface. Therefore, even if the riding comfort is improved, the change in the vehicle attitude is suppressed in accordance with the friction coefficient of the road surface. It is not something that can be done.

[0003] In the suspension mechanism disclosed in Japanese Patent Application Laid-Open Nos. 61-67606 and 63-88515, which is provided with a hydraulic shock absorber capable of gradually increasing and decreasing damping force, the outside air temperature is low and the road surface is low. If the damping force of the hydraulic shock absorber is increased when the friction coefficient of the hydraulic shock absorber is small, there is a disadvantage that the wheels are likely to be locked. Therefore, the outside air temperature is used as a parameter for controlling the damping force of the hydraulic shock absorber. That is, the condition for switching the damping force of the hydraulic shock absorber is changed in accordance with the outside air temperature, and the opportunity (frequency) of increasing the damping force of the hydraulic shock absorber when the outside air temperature is low is reduced. However, since the above suspension mechanism does not reduce the maximum value of the damping force of the hydraulic shock absorber, the damping force of the hydraulic shock absorber becomes excessive depending on the running conditions, which causes the wheels to be locked and the running stability of the vehicle to be stable. May be impaired.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the object of the present invention is to correct the control of the damping force of a hydraulic shock absorber by the temperature of the outside air, so that the damping force of the hydraulic shock absorber becomes excessive, It is an object of the present invention to provide a control device for a suspension mechanism, which prevents locking of the suspension mechanism.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a configuration of the present invention comprises a variable damping force type hydraulic shock absorber, a sensor for detecting a running state and a running state of a vehicle, and an output of the sensor. And an optimal damping force calculating means for calculating an optimal damping force value of the damping force of the hydraulic damper in accordance with the control means, wherein the hydraulic damper is controlled so as to have the optimum damping force obtained from the optimum damping force calculating means. In the control device for a suspension mechanism, the optimal damping force of the hydraulic shock absorber is corrected according to an outside air temperature detected by an outside air temperature sensor disposed outside the vehicle body.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention predicts that the coefficient of friction of a road surface changes according to the outside air temperature, and corrects the damping force of a hydraulic shock absorber to an optimum value. This is to change the maximum damping force that can be generated by the shock absorber. Preferably, the correction value is changed for each roll (lateral tilt) control, pitch control, dive (forward tilt) control, and squat (backward tilt) control of the vehicle. In other words, when the coefficient of friction of the road surface becomes low, the damping force of the hydraulic shock absorber is reduced, the roll of the vehicle body during turning and the pitch of the vehicle body during acceleration / deceleration are suppressed, the wheels are prevented from locking, and traveling safety is reduced. Ensure the nature. Especially,
When the outside air temperature becomes low, the friction coefficient of the road surface becomes small due to freezing or the like, the wheels are locked at the time of deceleration, and the cornering force at the time of cornering becomes small, and the vehicle tends to be understeer. Then, the vehicle body is rolled by reducing the damping force of the hydraulic shock absorber to reduce the load movement of the vehicle body.

In the roll control and the dive control, since the load applied to the wheels is large, if the correction width is increased, the effect of improving the attitude stability and running stability of the vehicle is great. When the vehicle is in a bouncing or bottoming state, no temperature correction is applied to the control of the damping force of the hydraulic shock absorber because the wheel does not slip even if the wheel locks.

[0008]

FIG. 1 is a plan view showing a schematic structure of a suspension mechanism according to the present invention. The suspension mechanism includes a variable damping force type hydraulic shock absorber A, an outside air temperature sensor 27 for detecting an outside air temperature, and an electronic control unit 35. The electronic control unit 35 is a sensor for detecting a running / driving state of the vehicle. C and an optimum damping force calculating means D for obtaining an optimum damping force based on the output of the sensor C
And a correcting means E for correcting the optimum damping force based on the outside air temperature.

That is, in the present invention, the damping force of the actuator 36 of each of the hydraulic shock absorbers A of the front, rear, left and right wheels 2 and 3 is controlled by the electronic control unit 35 according to the running state and the driving state. For this purpose, a steering angle sensor 24 is provided on the steering shaft of the steering wheel 4. Preferably, an outside air temperature sensor 27 is provided at the front of the vehicle body, and a vertical acceleration sensor 26 is provided near the vehicle center of gravity.
Is arranged. Further, a vehicle speed sensor 23 is provided to face the output shaft of the transmission, an accelerator sensor 25 is provided to face the accelerator pedal, and a brake sensor 22 is provided to face the brake pedal. The brake sensor 22 may be a switch that closes when a brake pedal is depressed, a switch of an exhaust brake, a switch of a retarder, or the like. The signals from the sensors 27, 26, 23, 25, and 22 described above are input to the electronic control unit 35.

As shown in FIG. 3, the mode determiner 28 inputs a signal corresponding to the running mode to the electronic control unit 35 based on the signal of the system switch 21. The brake dive determiner 29 outputs a brake dive control signal for suppressing the forward lean of the vehicle body based on the signal of the brake sensor 22 to the electronic control unit 3.
Enter 5 The signal of the vehicle speed sensor 23 is output to the deceleration calculator 3
0, a roll judging unit 31, a pitch judging unit 32, a high-speed running judging unit 33, and a vibration judging unit 34. The deceleration calculator 30 calculates the acceleration from the signal of the vehicle speed sensor 23. The roll determiner 31 inputs a control signal for suppressing the roll of the vehicle body to the electronic control device 35 based on the signal of the steering angle sensor 24. The pitch determination unit 32 inputs a control signal for suppressing the pitch of the vehicle body to the electronic control unit 35 based on the accelerator pedal depression speed detected by the accelerator sensor 25. The high-speed running determiner 33 inputs a signal indicating whether or not the vehicle is in a high-speed running state to the electronic control unit 35 based on the signal of the vehicle speed sensor 23. The vibration determiner 34 is a vertical acceleration sensor 2
Based on the signal of No. 6, a signal indicating whether the bouncing of the vehicle body is larger (bouncing) or smaller (bottoming) than a predetermined level is input to the electronic control unit 35.

In the present invention, in particular, the roll, pitch and bounce of the vehicle body are controlled, and the damping force of each hydraulic shock absorber A is controlled stepwise or continuously according to the outside air temperature. As shown in FIG. 2, the hydraulic shock absorber A is configured such that a piston 60 is inserted into a cylinder 56 and a chamber 58 is provided above the piston 60.
A chamber 59 is formed on the lower side, and an oil chamber 74 of the accumulator 70 is provided in one of the chambers 58, 59 with a known two-way check valve 71.
Connected via The pressure accumulator 70 is partitioned into an oil chamber 74 and a compressed air chamber 75 by a diaphragm 73 inside the container 72. A hollow rod 53 integral with the piston 60 protrudes from the upper end wall 56a via the sealing member 55. A mounting flange 54 is connected to the upper end of the rod 53, and the mounting flange 54 is connected to the vehicle body.
A mounting member 77 connected to the lower end wall 56b of the vehicle is connected to a suspension arm (not shown) supporting the wheels.

The basic configuration of the control valve B for adjusting the damping force of the hydraulic shock absorber A includes a valve chamber 67 formed inside the piston 60 and a valve body rotatably fitted to the valve chamber 67. 66
The control rod 52 is connected to the rod 53 from the valve body 66.
The actuator 36 is connected to the upper end of the control rod 52. Valve chamber 67
An annular groove is formed on the inner peripheral surface of the intermediate portion of the, and is communicated with the chamber 58 through the passage 61. In addition, arc-shaped grooves 63 a and 69 a formed on the inner peripheral surfaces of the upper and lower ends of the valve chamber 67 communicate with the chamber 59 via the passage 68. A passage 62 extending radially outward from an intermediate portion of an axial passage 76 of the valve body 66 is always in communication with the passage 61 through an annular groove, while check valves 64 and 6 of the passage 76 are provided.
A plurality of passages 63 extending radially outward from upper and lower ends than
Some of the 69 can be selectively communicated with the grooves 63a and 69a, respectively. Chamber 58 when hydraulic shock absorber A extends
Flows into the chamber 59 through the passages 61 and 62, the check valve 65, and the passages 69 and 68, and when the hydraulic shock absorber A is contracted, the oil in the chamber 59 flows through the passages 68 and 63, the check valve 64, and the passages 62 and 61. Through the chamber 58. The valve body 66 is rotated by the actuator 36, and the grooves 63 of the passages 63 and 69 extending from the passage 76.
a, 69a, the damping force F
Becomes smaller (see FIG. 5), and the damping force F increases as the number of passages 63, 69 extending from the passage 76 communicating with the grooves 63a, 69a decreases.

As shown in FIG. 3, the present invention provides a hydraulic shock absorber A
Is controlled so as to be the optimum damping force obtained from the optimum damping force calculating means D, and the optimum damping force of the hydraulic shock absorber A is corrected according to the outside air temperature. FIG. 4 is a flow chart of a control program for performing the above-described control by an electronic control device including a microcomputer. In the figure, p
11 to p20 represent each step of the control program. This program is repeatedly executed at predetermined time intervals. The control program is started at p11, the running state and the driving state are detected from the sensor C at p12, and it is determined whether the vehicle body is in the bouncing state at p13. If the body is in the bouncing state, proceed to p20. If the body is not in the bouncing state, go to p20.
At 14, it is determined whether or not the vehicle body is in a boating state. When the vehicle body is in the bottling state, the process proceeds to p20, and when the vehicle body is not in the bottling state, the optimal damping force F is obtained from the running state and the driving state in p15. Outside air temperature sensor 27 at p16
, A correction coefficient k corresponding to the outside air temperature t is obtained from the control map shown in FIG. At p18, the damping force F1 (=) corrected from the correction coefficient k and the optimum damping force F
F · k). The hydraulic shock absorber A is controlled so that the damping force becomes F1 at p19, and the process ends at p20.

[0014]

As described above, the present invention provides a variable damping force type hydraulic shock absorber, a sensor for detecting a running state and an operating state of a vehicle, and a damping force of the hydraulic shock absorber according to an output of the sensor. An optimal damping force calculating means for calculating the optimum optimal damping force value of the suspension mechanism, wherein the control device of the suspension mechanism controls the hydraulic shock absorber so that the optimal damping force obtained from the optimal damping force calculating means is obtained. The optimal damping force of the hydraulic shock absorber is corrected in accordance with the outside air temperature detected by an outside air temperature sensor disposed outside the device, and the maximum damping force that can be generated by the hydraulic shock absorber is changed in accordance with the outside air temperature. Therefore, when the outside air temperature is low, locking of the wheels during deceleration and understeering during turning are prevented, and the running stability of the vehicle is improved.

When the vehicle is in a bouncing or bottoming state, the temperature correction of the damping force of the hydraulic shock absorber is interrupted, so that an optimum damping force of the hydraulic shock absorber can be obtained while preventing slipping of the wheels. .

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of a suspension mechanism according to the present invention.

FIG. 2 is a side sectional view showing a schematic configuration of a variable damping force type hydraulic shock absorber.

FIG. 3 is a block diagram showing an outline of a control device of the suspension mechanism.

FIG. 4 is a flowchart of a program for controlling a damping force of a hydraulic shock absorber by an electronic control device including a microcomputer.

FIG. 5 is a diagram illustrating characteristics of a hydraulic shock absorber;

FIG. 6 is a diagram showing a control map for obtaining a correction coefficient of a damping force.

[Explanation of symbols]

A: Hydraulic shock absorber B: Control valve C: Sensor D: Optimum damping force calculation means E: Correction means 2: Front wheel 3: Rear wheel
4: steering wheel 21: system switch 22: brake sensor 23: vehicle speed sensor 24: steering angle sensor 2
5: accelerator sensor 26: vertical acceleration sensor 27: outside air temperature sensor 2
8: Mode determiner 29: Brake dive 30: Deceleration calculator 31: Roll determiner 32: Pitch determiner
33: High-speed running judgment unit 34: Vibration judgment unit 35: Electronic control unit 36: Actuator 52: Control rod
53: Rod 54: Mounting flange 55: Seal member 56: Cylinder 58, 59: Chamber 60: Piston
64, 65: check valve 66: valve body 67: valve chamber 70:
Accumulator 71: Two-way check valve 72: Container 73: Diaphragm 74: Oil chamber 75: Compressed air chamber 77: Mounting member

Claims (2)

[Claims] 1. A variable damping force type hydraulic shock absorber, a sensor for detecting a running state and an operating state of a vehicle, and an optimal damping force value of the damping force of the hydraulic shock absorber calculated according to an output of the sensor. And a control device for a suspension mechanism that controls the hydraulic shock absorber so as to have an optimum damping force obtained from the optimum damping force calculating means. A control device for a suspension mechanism, wherein an optimum damping force of the hydraulic shock absorber is corrected according to an outside air temperature detected by a sensor. 2. The method according to claim 1, wherein when the running state of the vehicle is one of bouncing and bottoming, the correction of the optimal damping force of the hydraulic shock absorber in accordance with the outside air temperature is interrupted.
3. The control device for a suspension mechanism according to claim 1.