JPH0635243B2 - Vehicle suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a vehicle for controlling the posture of a vehicle body by supplying and discharging a fluid to and from a fluid spring chamber provided for each suspension unit. Suspension system for automobiles.

(Prior art) A suspension unit having a fluid spring chamber is provided for each wheel, and fluid is supplied to the fluid spring chamber of the suspension unit on the contraction side during braking or acceleration at start, and from the fluid spring chamber of the suspension unit on the extension side. A vehicle suspension device is proposed in which fluid is discharged to reduce the ups and downs in the vehicle front-rear direction (when braking: nose dive, when starting: squat) that occur during braking or starting acceleration.

(Problems to be Solved by the Invention) However, for example, when the number of passengers exceeds the specified number or when a heavy load is placed, the internal pressure of the fluid spring chamber of the suspension unit on the rear side is particularly the pressure of the fluid supply source. Since the pressure becomes extremely high, the fluid is supplied from the fluid supply source to the fluid spring chamber of the rear suspension by anti-squat control in this state, no more fluid is supplied, and useless posture control is performed. Processing will be carried out.

The present invention has been made in view of the above problems, and when the internal pressure of the fluid spring chamber of the rear suspension unit becomes close to the internal pressure of the fluid supply source and normal fluid supply operation cannot be obtained, An object of the present invention is to provide a vehicle suspension device that can prevent unnecessary attitude control.

[Configuration of Invention] (Means and Actions for Solving Problems) That is, the vehicle suspension device according to the present invention is
The rear pressure sensor that detects the internal pressure of the fluid spring chamber of the rear suspension unit, and the fluid spring chamber of the rear suspension unit when a pressure in the spring chamber that is equal to or greater than a preset pressure value is detected by the rear pressure sensor. And a high-voltage posture control prohibiting means for prohibiting the posture control only with respect to the above.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, FS1 is a left front wheel side suspension unit, FS2 is a right front wheel side suspension unit,
RS1 is a suspension unit on the left rear wheel side, and RS2 is a suspension unit on the right rear wheel side. Each of these suspension units FS1, FS2, RS1, RS2
Since each has the same structure as each other, the suspension unit will be described by using the reference symbol S, except for the case of distinguishing between the front wheels and the rear wheels or the left wheels and the right wheels.

The suspension unit S includes a shock absorber 1. The shock absorber 1 includes a cylinder mounted on the wheel side, and a piston rod 2 having a piston slidably fitted in the cylinder and having an upper end supported on the vehicle body side. In addition, the suspension unit S is attached to the upper part of the shock absorber 1.
An air spring chamber 3 having a function of adjusting the vehicle height is provided coaxially with the piston rod 2. A part of the air spring chamber 3 is formed by a bellows 4, and air is supplied to and discharged from the air spring chamber 3 through a passage 2a provided in the piston rod 2 to raise or lower the vehicle height. Can be lowered.

Further, inside the piston rod 2, a control rod 5 having a valve 5a for adjusting the damping force at the lower end is arranged. The control rod 5 is a piston rod 2
The valve 6 is driven by being rotated by an actuator 6 attached to the upper end of the valve. By the rotation of the valve 5a, the damping force of the suspension unit is set to three levels of hard (hard), medium (medium), and soft (soft).

The compressor 11 compresses the air taken in from the air cleaner 12 and sends it to the high pressure reserve tank 15 a via the dryer 13 and the check valve 14. That is,
Since the compressor 11 compresses the air taken in from the air cleaner 12 and supplies it to the dryer 13, the compressed air dried by silica gel or the like in the dryer 13 is stored in the high-pressure reserve tank 15a. The return pump 16 has its suction port connected to the low-pressure reserve tank 15b and its discharge port connected to the high-pressure reserve tank 15a. Reference numeral 18 denotes a low pressure switch which is turned on when the pressure in the low pressure reserve tank 15b reaches or exceeds a first set value (eg, 0.6 kg / cm ² ). Then, when the low-pressure pressure switch 18 outputs an ON signal, the return pump 16 is driven by a return pump relay 17 which is turned ON by a signal from a control unit 36 described later. Further, the return pump 16 is stopped by the return pump relay 17 which is turned off by a signal from the control unit 36 when the low pressure switch 18 outputs an off signal. As a result, the pressure in the low pressure reserve tank 15b is always kept below the first set value.

Then, air is supplied from the high-pressure reserve tank 15a to each suspension unit S as shown by solid line arrows in FIG. That is, the high pressure reserve tank 15a
Compressed air in the suspension units FS1, F is supplied through the air supply flow rate control valve 19, the front air supply solenoid valve 20, the check valve 21, the front left solenoid valve 22, and the front right solenoid valve 23.
It is sent to S2. Similarly, high pressure reserve tank 1
The compressed air in 5a is sent to the suspension units RS1 and RS2 via the air supply flow rate control valve 19, the rear air supply solenoid valve 24, the check valve 25, the rear left solenoid valve 26, and the rear right solenoid valve 27. It

On the other hand, the exhaust from each suspension unit S is performed as indicated by the broken line arrow in FIG. That is, the compressed air in the suspension units FS1 and FS2 is supplied to the low pressure reserve tank 15b via the exhaust direction switching valve 28 including the solenoid valves 22 and 23 and the three-way valve, and the solenoid valves 22 and 23. , Exhaust direction switching valve 28, check valve 29, dryer 1
3, it may be discharged to the atmosphere via the exhaust solenoid valve 31, the check valve 46 and the air cleaner 12. Similarly, the suspension units RS1 and RS2
Compressed air in the low pressure reserve tank 15b passes through the solenoid valves 26 and 27 and the exhaust direction switching valve 32.
When it is fed into the solenoid valve 26, 27,
It may be discharged to the atmosphere via the exhaust direction switching valve 32, the check valve 33, the dryer 13, the exhaust solenoid valve 31, the check valve 46 and the air cleaner 12. A passage having a smaller diameter than the passage that directly connects the exhaust direction switching valves 28 and 32 and the low pressure reserve tank 15b is provided between the check valves 29 and 33 and the dryer 13.

The above-mentioned solenoid valves 22, 23, 26, 2
As shown in FIGS. 2 (A) and 2 (B), 7, 28 and 32 indicate that air flows as indicated by arrow A when ON (energized state) and as indicated by arrow B when OFF (non-energized state). Allows air circulation, respectively. Also, the air supply solenoid valves 20, 2
4 and the exhaust solenoid valve 31, as shown in FIGS. 3 (A) and 3 (B), allow air to flow as indicated by arrow C when ON (energized state) and flow air when OFF (non-energized state). Prohibit In addition, the supply air flow control valve 19 is ON
In the state (energized), air flows through the orifice o as shown in FIG.
In the FF state (non-energized), air flows through the orifice o and the large diameter path D as shown in FIG.

34F is the lower arm 3 of the right front suspension of the vehicle.
5 is a front vehicle height sensor that is mounted between the vehicle body and the vehicle body to detect the front vehicle height; and 34R is a rear vehicle height that is mounted between the lateral rod 37 of the rear left suspension of the vehicle and the vehicle body to detect the rear vehicle height. It is a sensor. The signals detected by the vehicle height sensors 34F and 34R are supplied to a control unit 36 equipped with a microcomputer.

A vehicle speed sensor 38 is incorporated in the speedometer and supplies the detected vehicle speed signal to the control unit 36. Reference numeral 39 denotes an acceleration sensor that detects the acceleration acting on the vehicle body, and supplies the detected acceleration signal to the control unit 36. Reference numeral 30 is a roll control mode selection switch for selecting the roll control mode from soft (SOFT), auto (AUTO), and sport (SPORTS), and 40 is a steering sensor for detecting the rotation speed of the steering wheel 41, that is, the steering angular speed. Reference numeral 42 is an accelerator opening sensor for detecting the depression angle of the accelerator pedal of the engine (not shown). The signals detected by the roll control selection switch 30, the sensors 40 and 42 are supplied to the control unit 36. Reference numeral 43 is a compressor relay for driving the compressor 11, and the compressor relay 43 is controlled by a control signal from the control unit 36. 44 is a high pressure reserve tank 15a
It is a high pressure switch which is turned on when the internal pressure becomes equal to or lower than a ^second set value (for example, 9.5 kg / cm ² ). Then, in the compressor 11, when the pressure in the high pressure reserve tank 15a becomes equal to or lower than the second set value and the high pressure switch 44 outputs an ON signal,
It is driven by a compressor relay 43 which is turned on by a signal from the control unit 36. and again,
When the high pressure switch 44 outputs an off signal, the compressor 11 is stopped by a compressor relay 43 which is turned off by a signal from the control unit 36.
As a result, the pressure in the high pressure reserve tank 15a is always maintained at the second set value or higher. In this case, even if the high pressure switch 44 is turned on, the drive of the compressor 11 is prohibited when the low pressure switch 18 is turned on, that is, when the return pump 16 is driven. Reference numeral 45 denotes a rear pressure sensor provided in a passage that connects the solenoid valves 26 and 27 to each other.
The internal pressure P _R of the rear suspension units RS1 and RS2 is detected.

The solenoid valves 19, 20, 22, 2 described above
Control of 3, 24, 26, 27, 28, 31 and 32 is performed by a control signal from the control unit 36.

Next, the operation of the suspension device according to the embodiment configured as described above will be described.

This suspension device has an attitude control function and a vehicle height adjustment function. Here, the attitude control function for suppressing the attitude change occurring in the vehicle body will be described.

When the steering wheel 41 is steered to the right, the vehicle body tries to roll to the left. On the other hand, the control unit 36 turns on the air supply solenoid valves 20 and 24 for a set time, and also controls the solenoid valves 23 and 27 of the right wheel.
Is turned on, and after the set time has elapsed, the exhaust direction switching valve 32 is turned on. As a result, the set amount of compressed air is supplied from the high-pressure reserve tank 15a to the air spring chambers 3 of the left suspension units FS1 and RS1, and the right suspension units FS2 and RS2 are supplied.
The set amount of compressed air is discharged from each of the air spring chambers 3 to the low pressure reserve tank 15b. This suppresses the displacement of the vehicle body that attempts to roll to the left. In this state, that is, the set amount of compressed air is supplied to the air spring chambers 3 of the left suspension units FS2 and RS2, and the set amount of compressed air is discharged from the air spring chambers 3 of the right suspension units FS1 and RS1. The state is maintained continuously. When the control unit 36 detects that the steering sensor 40 makes the steering neutral, or the acceleration sensor 39 reduces the lateral acceleration, the control unit 36 solenoids. The valves 23 and 27 are turned off, and the exhaust direction switching valve 32 is turned off.
As a result, the air spring chambers 3 of the left and right suspension units are kept at the same pressure as before the control was started.

On the other hand, when the steering wheel 41 is steered to the left, the vehicle body tries to roll to the right. On the other hand, the control unit 36 turns on the air supply solenoid valves 20 and 24 for the set time, and at the same time, the left solenoid valve 2
2, 26 are turned on, and after the set time has elapsed, the exhaust direction switching valve 32 is turned on. As a result, each air spring chamber 3 of the right suspension unit FS2, RS2
The compressed air is supplied from the high pressure reserve tank 15a to a set amount, and the left suspension unit FS1,
Low pressure reserve tank 15b from each air spring chamber 3 of RS1
The set amount of compressed air is discharged to. As a result, the displacement of the vehicle body attempting to roll to the left is suppressed. Hereinafter, control is performed in the same manner as when the steering wheel 41 is steered to the right.

Next, a description will be given of attitude control in the case of suppressing a nose dive in which the front portion of the vehicle body sinks due to the negative acceleration acting on the vehicle body when the brake is operated. When the acceleration sensor 39 detects that the negative acceleration in the front-rear direction of the vehicle body is equal to or greater than the set value, for example, when the brake is operated, the control unit 36 turns on the air supply solenoid valve 20 for the set time, and also controls the rear wheel. The solenoid valves 26 and 27 are turned on, and after the set time has elapsed, the exhaust direction switching valve 32 is turned on. As a result, the set amount of compressed air is supplied from the high pressure reserve tanks 15a of the front wheel suspension units FS1 and FS2, and the set amount of compressed air is discharged from the rear wheel suspension units RS1 and RS2 to the low pressure reserve tank 15b. In this way, the nose dive is suppressed. This state continues until the negative acceleration is weakened. Then, when the acceleration sensor 39 detects that the negative acceleration is weakened thereafter, the control unit 3
6 turns on the air supply solenoid valves 22 and 23 for a set time and turns off the rear-wheel solenoid valves 26 and 27. As a result, a set amount of compressed air is discharged from the front wheel suspension units FS1 and FS2 to the low pressure reserve tank 15b, and the high pressure reserve tank 15a is discharged to the rear wheel suspension units RS1 and RS2.
A set amount of compressed air is supplied from. In this way, each air spring chamber 3 of each suspension unit S is returned to the state before the start of control.

Next, the attitude control in the case of suppressing the squat in which the front portion of the vehicle body lifts and the rear portion of the vehicle body sinks due to the acceleration acting on the vehicle body when the vehicle starts to accelerate will be described. When the accelerator opening sensor 43, the acceleration sensor 39, or the like detects that the vehicle is in rapid acceleration, the control unit 36 turns on the air supply solenoid valve 24 for a set time and turns on the solenoid valves 22 and 23 of the front wheels. Further, after the set time has elapsed, the exhaust direction switching valve 32 is turned on. As a result, the set amount of compressed air is discharged from the front wheel suspension units FS1 and FS2 to the low pressure reserve tank 15b, and the set amount of compressed air is supplied to the rear wheel suspension units RS1 and RS2 from the high pressure reserve tank 15a. . In this way, the squat is suppressed. This state is continued until the acceleration is weakened. Then, after that, the control unit 36 controls the accelerator opening sensor 42.
Alternatively, when the acceleration sensor 39 or the like detects that the rapid acceleration is weakened, the control unit 36
Turns on the air supply solenoid valve 20 and the rear-wheel solenoid valves 26 and 27 for a set time, and turns off the front-wheel solenoid valves 22 and 23. As a result, the set amount of compressed air is supplied from the high pressure reserve tank 15a to the suspension units FS1 and FS2 for the front wheels, and the suspension units RS1 and R for the rear wheels are provided.
The set amount of compressed air is discharged from S2 to the low pressure reserve tank 15b. In this way, each air spring chamber 3 of each suspension unit S is returned to the state before the start of control.

Here, when performing the posture control of the anti-nose dive and the anti-squat, the internal pressure of each air spring chamber 3 of the rear suspension units RS1, RS2 is checked, and the air supply control accompanying the posture control for the air spring chamber 3 is performed. It is judged whether or not it is possible.

FIG. 5 shows the rear suspension units RS1 and RS.
2 is a flowchart showing a process of determining whether or not the attitude control of the air spring chamber 3 of No. 2 is performed. First, the control unit 36 reads the average internal pressure value in each air spring chamber 3 of the rear suspension units RS1 and RS2 from the rear pressure sensor 45. Then, it is judged whether or not the pressure value P _R is equal to or higher than a preset posture control impossible high pressure value (for example, 7.5 kg / cm ² ) (step S1). If "NO" in step S1, that is, the average air pressure in the rear air spring chamber 3 is less than 7.5 kg / cm ² , and it is determined that compressed air supply control is possible, the front suspension unit FS1 , FS2 and the rear suspension units RS1 and RS2 perform the usual anti-nose dive or anti-squat attitude control (step S2).

On the other hand, if it is determined that P _R ≧ 7.5 kg / cm ² by the internal pressure determination of the air spring chamber 3 of the rear suspension units RS1 and RS2 before the posture control in step S1, the rear air spring chamber 3 is determined. Only for the above, the compressed air supply / exhaust operation by the attitude control is prohibited (step S
3). As a result, it is not necessary to perform a wasteful attitude control operation in which air is not supplied even if compressed air is supplied during anti-squat control, even though the rear side air spring chamber 3 is in a high pressure state. . It should be noted that only the internal pressure of the rear side air spring chamber 3 is detected, and even if the internal pressure of the rear side air spring chamber 3 becomes 7.5 kg / cm ² or more, only for the rear side air spring chamber 3, Although the compressed air supply / discharge control by the attitude control is prohibited, this is particularly the case in passenger cars, where the change in the internal pressure of the air spring chamber 3 on the front side with respect to the change in the load due to the occupant and luggage causes the change in the rear side. Considering the fact that it is extremely small compared to the above, only the supply / discharge control for the air spring chamber 3 on the front side is secured, and even if the internal pressure of the air spring chamber 3 on the rear side is 7.5 kg / cm ² or more. Since the attitude control for the air spring chamber 3 on the front side is executed even if the height becomes extremely high, the attitude control effect can be obtained although it is inferior to the case where the attitude control on the rear side is simultaneously performed.

Therefore, according to the suspension device configured as described above,
Compressed air is supplied to the air spring chamber 3 of the compression side suspension unit S in accordance with the amount of ups and downs of the front and rear parts of the vehicle body that may occur due to the acceleration generated in the front-rear direction of the vehicle body, and the extension side suspension unit S Not only can the posture control of the anti-nose dive or the anti-squat be performed by exhausting air from the air spring chamber 3 of the above, but the internal pressure of the rear air spring chamber 3 is too high and the air supply / exhaust operation accompanying the posture control cannot be performed normally. If determined, the posture control is prohibited only for the rear suspension units RS1 and RS2, so that lean posture control is possible.

[Advantages of the Invention] As described above, according to the present invention, the rear pressure sensor that detects the internal pressure of the fluid spring chamber of the rear suspension unit and the spring chamber pressure that is equal to or higher than the pressure value preset by the rear pressure sensor When it is detected, the high-pressure posture control prohibiting means for prohibiting the posture control only for the fluid spring chamber of the rear suspension unit is provided.
For example, if the internal pressure of the fluid spring chamber of the suspension unit on the rear side becomes close to the pressure of the fluid supply source due to the occupant in the rear seat or the luggage in the rear luggage compartment, and normal fluid supply cannot be obtained, it is unnecessary. It is possible to prevent the posture control from being performed, and even if the internal pressure of the rear fluid spring chamber becomes equal to or higher than the set pressure value, the posture control for the front fluid spring chamber is executed. Although it is inferior to the case where the rear side posture control is performed at the same time, it is possible to provide the vehicle suspension device that can obtain the posture control effect.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a vehicle suspension device according to an embodiment of the present invention, and FIGS. 2 (A) and 2 (B) respectively show driving and non-driving states of a three-way valve in the vehicle suspension device. FIGS. 3 (A) and 3 (B) are views showing driving and non-driving states of the solenoid valve in the vehicle suspension device, and FIGS. 4 (A) and (B) are views in the vehicle suspension device, respectively. FIG. 5 is a flowchart showing a drive / non-drive state of the supply air flow rate control valve, and FIG. 5 is a flowchart showing an operation for determining whether or not attitude control for the rear suspension unit of the vehicle suspension device is possible. FS1, FS2, RS1, RS2 ... Suspension unit, 3 ... Air spring chamber, 4 ... Bellows, 11 ...
Compressor, 15a ... High pressure reserve tank, 15b
...... Low pressure reserve tank, 16 ...... Return pump, 1
7 ... Return pump relay, 18 ... Low pressure switch, 36 ... Control unit, 38 ... Vehicle speed sensor, 39 ... Acceleration sensor, 40 ... Steering sensor, 43
...... Compressor relay, 44 …… High pressure switch,
45 ... Rear pressure sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Tadamoto 5-3-8 Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (72) Inventor Shozo Takizawa 5-33-8 Shiba, Minato-ku, Tokyo No. Mitsubishi Motors Co., Ltd. (72) Inventor Tetsuya Terada 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Co., Ltd. (56) Bibliographic data Sho 64-45507 (JP, U) 64-45511 (JP, U) Actual public Sho 63-41211 (JP, Y2)

Claims (1)

[Claims] 1. A posture control function of detecting a factor that causes acceleration in the front-rear direction of a vehicle body, supplying fluid to a fluid spring chamber of a suspension unit on the contraction side, and discharging the fluid from a fluid spring chamber of a suspension unit on the extension side. In the vehicle suspension device that has the rear pressure sensor that detects the internal pressure of the fluid spring chamber of the rear suspension unit, and when the rear pressure sensor detects a pressure in the spring chamber that is equal to or greater than a preset pressure value, A suspension device for a vehicle, comprising: a high-pressure posture control prohibiting unit that prohibits posture control only for a fluid spring chamber of a rear suspension unit.