JPH0635248B2 - Vehicle suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention supplies air to an air spring chamber of a suspension unit on the outside of a turn and discharges air from a suspension unit on the inside of a turn during turning. By doing so, the present invention relates to a vehicle suspension device that prevents the occurrence of rolls.

(Prior Art) A suspension unit having an air spring chamber is provided for each wheel, and air is supplied to the air spring chamber of the suspension unit on the outer side of the turn at the time of turning, and the air is discharged from the suspension unit on the inner side of the turn. There is known a vehicle suspension device that prevents the occurrence thereof.

(Problems to be solved by the invention) In such a suspension device, a high pressure side reserve tank and a low pressure side reserve tank are provided, and air is supplied to the air spring chamber from the high pressure side reserve tank and discharged from the air spring chamber. A return pump that sends the stored air to the low-pressure side reserve tank and squeezes the air in the low-pressure side reserve tank to the high-pressure side reserve tank is used as a closed loop system, and the humidity of the outside air into the system It is possible to prevent the intrusion of rust, and thereby to reduce the trouble such as the generation of rust in each part.

However, in such a suspension device, when the load capacity or the number of passengers is large, the absolute amount of air required for the system as a closed loop increases, so that means for adjusting the absolute amount of air in the system is required. Become.

Therefore, the applicant of the present application has previously proposed a suspension device in which a compressor for compressing the outside air and sending it to the high pressure side reserve tank is provided separately from the above return pump in such a suspension device. In the proposed device, the return pump is driven when the internal pressure of the low pressure side reserve tank becomes higher than the first set value, and when the internal pressure of the high pressure side reserve tank becomes lower than the second set value. It is configured to drive a compressor.

However, in the device configured as described above, when the above-described supply / discharge control during turning and the vehicle height adjustment for increasing the vehicle height overlap, the internal pressure of the low-pressure side reserve tank is set to the first value. There is a possibility that the internal pressure of the high-pressure side reserve tank is higher than the set value and lower than the second set value, so that the return pump and the compressor are simultaneously driven. Furthermore, from this state, even after the internal pressure of the high pressure side reserve tank becomes higher than the second set value and the compressor stops, the internal pressure of the low pressure side reserve tank is still higher than the first set value, so the return pump is still driven. It is possible that a situation of continuing to occur. In that case, there is a problem that the internal pressure of the high-pressure side reserve tank becomes unnecessarily high and the durability of the tank is deteriorated, or unnatural control is performed.

The present invention has been made in view of the above points, and an object thereof is to provide a vehicle suspension device that solves the above problems by appropriately controlling a return pump and a compressor.

[Configuration of Invention] (Means and Actions for Solving Problems) An air spring chamber is provided for each suspension unit that supports each wheel, and compressed air is supplied from the high-pressure side reserve tank during turning to a suspension unit outside the turning. The air from the suspension unit inside the turning is discharged to the low-pressure side reserve tank,
In a vehicle suspension device that prevents the occurrence of rolls, a high-pressure pressure detection unit that detects the internal pressure of the high-pressure reserve tank, a low-pressure pressure detection unit that detects the internal pressure of the low-pressure reserve tank, and the high-pressure reserve A compressor for compressing and sending the outside air to the tank, a return pump for compressing the air in the low-pressure side reserve tank and sending it to the high-pressure side reserve tank, and a low-pressure side reserve tank detected by the low-pressure pressure detection means. The return pump is driven when the internal pressure is higher than the first set value, and the compressor is driven when the internal pressure of the high pressure side reserve tank detected by the high pressure detecting means is lower than the second set value. However, even if the internal pressure of the high pressure side reserve tank is lower than the second set value, the low pressure side reserve tank When the internal pressure of the click is higher than the first set value is a vehicle suspension system, characterized by comprising a control means for prohibiting the driving of the compressor.

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 left rear wheel side suspension unit, RS
2 is a suspension unit on the right rear wheel side. Each of these suspension units FS1, FS2, RS1, R
Since S2 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 suction port of the compressor 16 is connected to the low pressure reserve tank 15b, and the discharge port thereof is connected to the high pressure reserve tank 15a. Reference numeral 18 denotes a pressure switch which is turned on when the pressure in the low pressure reserve tank 15b becomes equal to or higher than a first set value (for example, atmospheric pressure). When the compressor 16 outputs an ON signal of the pressure switch 18, the compressor 16 is driven by a compressor relay 17 which is turned on by a signal from a control unit 36 described later. As a result, the pressure in the low pressure reserve tank 15b is always kept below the first set value.

The air is supplied from the high pressure reserve tank 15a to each suspension unit S as shown by the solid line arrow in FIG. That is, the compressed air in the high pressure reserve tank 15a is supplied to the suspension units FS1 and FS via 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.
Delivered to 2. Similarly, the high pressure reserve tank 15
The compressed air in a 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. To be done.

On the other hand, the exhaust from each suspension unit S is performed as shown 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 (B), reference numerals 7, 28 and 32 denote air flow as indicated by an arrow A when ON (energized state) and air as indicated by an arrow B when OFF (non-energized). To allow the distribution of each. The air supply solenoid valves 20 and 24 and the exhaust solenoid valve 31 are shown in FIGS. 3 (A) and 3 (B).
As shown in, the air flow is allowed as shown by an arrow C when it is off (non-energized state), and the air flow is prohibited when it is off (non-energized state). Further, when the supply air flow control valve 19 is in the off state (non-energized), the orifice o as shown in FIG.
The air flow rate is small because it circulates through the air passage, and the air flow rate is large in the ON state (energized state) because the air circulates through the orifice o and the large path D as shown in FIG. 4 (B). .

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
This is a pressure switch that is turned on when the internal pressure falls below a ^second set value (for example, 7 kg / cm ² ), and the signal of this pressure switch 44 is supplied to the control unit 36.
Then, when the pressure in the high-pressure reserve tank 15a becomes equal to or lower than the set value and the pressure switch 44 is turned on, the control unit 36 turns on the pressure switch 18, that is, when the compressor 16 is driven, It is configured to prohibit driving. Reference numeral 45 is a pressure sensor provided in a passage that connects the solenoid valves 26 and 27 to each other, and detects the internal pressure of the rear suspension units RS1 and RS2.

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 apparatus according to the embodiment configured as described above will be described. This device has a posture control function and a vehicle height adjusting mechanism. First, the attitude control function of 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. Then, 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 causes the solenoid valve to move. 23 and 27 are turned off, and the exhaust direction switching valve 32 is turned off. As a result, the air spring chambers 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. In response to this, the control unit 36 turns on the air supply solenoid valves 20 and 24 for a set time, and at the same time, controls the solenoid valve 2 for the left wheel.
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 solenoids 26 and 27. As a result, the front wheel suspension unit FS
The set amount of compressed air is discharged from the first 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, each air spring chamber 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, when the control unit 36 thereafter detects that the rapid acceleration is weakened by the accelerator opening sensor 42, the acceleration sensor 39, or the like, the same control unit 36 is detected.
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 of each suspension unit S is returned to the state before the start of control.

By the way, while the roll control as described above is being executed, the drive of the return pump and the compressor 11 is controlled according to the determinations of the high pressure side pressure switch 44 and the low pressure side pressure switch 18. First, it is determined whether the pressure of the pressure switch 18 is on, that is, is equal to or higher than the first set value (step S1). If the determination in step S1 is "NO", the return pump 16 is stopped (step S2). Then, it is determined whether the pressure switch 44 on the high pressure side is on, that is, is equal to or less than the second set value (step S3). In the determination of step S3, "N
When it is determined to be "O", the compressor 11 is stopped, and when it is determined to be "YES", the compressor 11 is stopped.
Is driven.

By the way, when it is determined to be "YES" in the step S1, it is determined whether or not the high pressure side pressure switch 44 is turned on (step S6). If it is on, the compressor 11 is stopped (step S7). If it is not turned on, the return pump 16 is driven (step S8). That is, the above steps S1, S6 to S8
The pressure switch 18 on the low pressure side is turned on by the processing of
When the condition for driving the return pump 16 is satisfied, and when the compressor 11 is driven, the compressor 11 is stopped. That is, the drive of the return pump 16 is given priority over the compressor 11. That is, at the point a in FIG. 5, the drive condition of the compressor 11 is also satisfied, but the drive condition of the return pump 16 is also satisfied, so that the drive of the return pump 16 is prioritized, so only the return pump 16 is turned on. Then, the compressor 11 is stopped.

[Effects of the Invention] As described in detail above, according to the present invention, when air is supplied from the high-pressure side reserve tank to each air spring chamber by adjusting the vehicle height, only the internal pressure of the high-pressure side reserve tank decreases and the low pressure decreases. Since the internal pressure of the high-side reserve tank does not rise, outside air compressed by the compressor will be supplied to the high-pressure side reserve tank when the internal pressure of the high-side reserve tank becomes lower than the second set value. The absolute amount of air required in the system as a closed loop constituted by the reserve tank, the low pressure side reserve tank, and the air spring chambers can be increased, and the roll control can be appropriately performed during turning traveling. Further, even if the internal pressure of the high pressure side reserve tank is lower than the second set value, the control means prohibits the drive of the compressor when the internal pressure of the low pressure side reserve tank is higher than the first set value. It is possible to eliminate the above-described problems caused by simultaneous supply and discharge control during traveling and vehicle height adjustment for increasing the vehicle height, and the return pump and the compressor being driven at the same time.

[Brief description of drawings]

FIG. 1 is a diagram showing a vehicle suspension device according to an embodiment of the present invention, FIG. 2 is a diagram showing a three-way valve driven / non-driven state, and FIG. 3 is a solenoid valve driven / non-driving state. Fig. 4 is a diagram showing driving and non-driving states of the supply air flow control valve, Fig. 5 is a flow chart showing driving of the return pump, and Fig. 6 is a pressure change in the high pressure side reserve tank and the low pressure side reserve tank. FIG. 3 is a diagram showing driving of a return pump and a compressor. 15a ... high pressure reserve tank, 15b ... low pressure reserve tank, 19 ... supply air flow control valve, 22, 23,
26, 27 ... Solenoid valve, 36 ... Control unit, 45 ... Pressure sensor.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shozo Takizawa 5-3-8 Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (72) Inventor Minoru Tadamoto 5-33-8 Shiba, Minato-ku, Tokyo No. Mitsubishi Motors Corporation (56) Reference JP-A-47-44527 (JP, A) JP-A-62-199510 (JP, A) JP-A-62-178412 (JP, A) JP-B-48- 20571 (JP, B2)

Claims (1)

[Claims] An air spring chamber is provided for each suspension unit that supports each wheel, and compressed air is supplied from a high pressure side reserve tank to the air spring chamber of a suspension unit on the outside of a turn during turning, and the suspension on the inside of the turn is provided. In a vehicle suspension device that prevents the generation of rolls by discharging air from the unit to the low pressure side reserve tank, a high pressure detecting means for detecting the internal pressure of the high pressure side reserve tank, and the low pressure side reserve tank. Low pressure detection means for detecting the internal pressure of, a compressor for compressing and sending the outside air to the high pressure side reserve tank, a return pump for compressing the air of the low pressure side reserve tank and sending it to the high pressure side reserve tank, The internal pressure of the low-pressure side reserve tank detected by the low-pressure pressure detection means is the first The return pump is driven when the pressure is higher than the set value, and the compressor is driven when the internal pressure of the high pressure side reserve tank detected by the high pressure detecting means is lower than the second set value, And a control means for prohibiting driving of the compressor when the internal pressure of the low-side reserve tank is higher than the first set value even if the internal pressure of the low-side reserve tank is lower than the second set value. Characteristic vehicle suspension device.