JPH01101211A - Vehicle suspension device - Google Patents

Abstract

PURPOSE:To prevent attitude control trouble from being generated in a suspen sion device by means of an air spring by annunciating abnormality when the low pressure switch of a low pressure reserve tank is left switched off and the number of times of fluid exhaust action detect reaches the prescribed number of times. CONSTITUTION:A control unit 36 detects whether exhaustion is performed or not from valve control signals with respect to solenoid valves 22, 23, 26, 27 accompanying car body attitude control. At the same time exhaust start with respect to a low pressure reserve tank 15b, an exhaust action detect count er CT is counted up. In this case, when a low pressure switch 18 is in an off state and the internal pressure of the low pressure reserve tank 15b is under a setting pressure and a counter value reaches more than a defined value, it is judged as abnormal condition so as to raise an alarm. When the low pressure switch 18 is in an on state and the internal pressure of the tank becomes more than the setting pressure, the low pressure switch 18 is judged as normal. With this arrangement, attitude control trouble is prevented from being generated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention supplies and exhausts compressed air to and from an air spring chamber provided in each suspension unit of a vehicle body, thereby improving the posture of the vehicle body. The present invention relates to a vehicle suspension device that controls a vehicle suspension system.

(Prior art) A suspension unit having an air spring chamber is provided for each wheel. For example, when turning, air is supplied to the air spring chamber of the suspension unit 0 on the compression side, and air is supplied from the air spring chamber of the suspension unit on the rebound side. A vehicle suspension device has been proposed that discharges a set amount of fluid to reduce roll of the vehicle body that occurs when turning.

In such a suspension system for a vehicle, an air spring chamber is provided in each suspension unit for each wheel, and compressed air from a high-pressure reserve tank is supplied to the air spring chamber of the compression side suspension unit. Rolling is prevented by discharging air from the air spring chamber of the suspension unit into a low-pressure reserve tank. Therefore, the internal pressure of the high-pressure reserve tank is always a high pressure value that exceeds the supply air control pressure for the air supply side air spring chamber, and the internal pressure of the low-pressure reserve tank is always a low pressure value that is below the exhaust control pressure for the exhaust side air spring chamber. Retained. Here, for example, the low-pressure reserve tank is provided with a low-pressure switch that is activated when the low pressure reaches a preset low pressure value, and the return pump between the low-pressure reserve tank and the high-pressure reserve tank is activated by the activation of this low-pressure switch. The internal pressure of the low pressure reserve tank is always maintained below the set low pressure value.

(Problem to be Solved by the Invention) However, if the low pressure switch breaks down, problems may occur, such as the return pump not being driven even if the internal pressure of the low pressure reserve tank exceeds the set low pressure value. It becomes difficult to exhaust air from the air spring chamber during control. In this case, there is a risk of loss of posture control.

Therefore, it is necessary to constantly monitor the operating state of the low pressure switch.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a suspension device for a vehicle that can immediately detect an abnormality in a low pressure switch and prevent the occurrence of attitude control malfunctions. .

[Structure of the Invention] (Means and Effects for Solving the Problems) That is, the vehicle suspension device according to the present invention is provided in a low pressure reserve tank and is activated when the internal pressure of the tank reaches a preset low pressure value or higher. a low pressure switch that detects a fluid discharge operation from the air spring chamber to the low pressure reserve tank accompanying posture control; a counting means that counts the number of times the fluid discharge operation is detected by the fluid discharge detection means; switch abnormality detection means for detecting an abnormality in the low pressure switch when the number of detected fluid discharge operations counted by the counting means reaches a predetermined number while the low pressure switch remains inoperative; It is composed of

(Example) An example of the present invention will be described below with reference to the drawings.

In Fig. 1, FSl is a suspension unit on the left front wheel side, FS2 is a suspension unit on the right front wheel side,
R81 is a suspension unit for the left rear wheel, and R82 is a suspension unit for the right rear wheel. Each of these suspension units) FSI, FS2. R8I, RS2
Since the suspension units have the same structure, the suspension units will be described using the reference numeral S, unless the suspension units for the front wheel and the rear wheel or for the left wheel and the right wheel are explained separately.

The suspension unit S includes a shock absorber 1. This shock absorber 1 includes a cylinder attached to a 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 top of this shock absorber L.
An air spring chamber 3 having a vehicle height adjustment function is provided coaxially with the piston rod 2. This air spring chamber 3 is partially formed by a bellows 4, and by supplying and discharging air to and from this air spring chamber 3 through a passage 2a provided in the piston rod 2, the vehicle height can be increased or It can be lowered.

Further, a control rod 5 is disposed inside the piston rod 2 and has a valve 5a at its lower end for adjusting the damping force. The control rod 5 is the piston rod 2
It is rotated by an actuator 6 attached to the upper end of the valve 5a to drive the valve 5a.

By rotating the valve 5a, the damping force of the suspension unit is set to three levels: hard, medium, and soft.

The compressor 11 compresses the atmospheric air taken in from the air cleaners 1 and 2, and connects the dryer 13 and check valve 14.
It is fed to the high pressure reserve tank 15a via. That is, since the compressor 11 compresses the atmospheric air taken in from the air cleaner 12 and supplies it to the dryer 13, 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. 18 is a low pressure reserve tank 15b
When the pressure inside is set to the first setting value (for example, 0.6Kg/cd
) This is a low-pressure switch that turns on when the pressure exceeds. When the low pressure switch 18 outputs an on signal, the return pump 16 is activated by the control unit 3, which will be described later.
Return pump relay 17 turned on by the signal from 6
Driven by. Further, when the low pressure switch 18 outputs an off signal, the return pump 16 is stopped by the return pump relay 17, which is turned off by a signal from the control unit 36.

As a result, the pressure within the low pressure reserve tank 15b is always maintained below the first set value.

Air is supplied from the high-pressure reserve tank 15a to each suspension unit S as shown by solid arrows in FIG. That is, the high pressure reserve tank 15a
The compressed air inside is supplied to the air supply flow control valve 19, the front air supply solenoid valve 20, the check valve 21, the front left corner solenoid valve 22. Suspension unit FSI via front useful solenoid valve 23.

Sent to FS2. Similarly, the compressed air in the high pressure reserve tank 15a is supplied to the suspension unit via the air supply flow control valve 19, the rear air intake solenoid valve 24, the check valve 25, the rear Tachikawa solenoid valve 26, and the rear solenoid valve 27. R8I, R8
2.

On the other hand, exhaust from each suspension unit S is performed as shown by the broken line arrows in FIG. That is, the compressed air in the suspension units FS1 and FS2 is fed into the low pressure reserve tank 15b via the solenoid valve 22.23 and the exhaust direction switching valve 28 consisting of a three-way valve; , exhaust direction switching valve 28, check valve 29, dryer 1
3. The air may be discharged to the atmosphere via the exhaust solenoid valve 31, check valve 46, and air cleaner 12. Similarly, suspension units R8I, R82
The compressed air in
and solenoid valves 26.27,
It may be discharged to the atmosphere via the exhaust direction switching valve 32, check valve 33, dryer 13, exhaust solenoid valve 31, check valve 46, and air cleaner 12. Note that a passage is provided between the check valve 29.33 and the dryer 13, which has a smaller diameter than the passage that directly communicates the exhaust direction switching valve 28.32 and the low pressure reserve tank 15b.

In addition, the above-mentioned solenoid valve 22.23°26.2
7.28 and 32, as shown in Figures 2 (A) and (B), flow air as shown by arrow A when ON (energized state) and flow as arrow B when OFF (de-energized state). Each allows air circulation. In addition, the air supply solenoid valve 20.2
4 and exhaust solenoid valve 31 as shown in Fig. 3 (A) and C.
As shown in B), when ON (energized state), air circulation is allowed as shown by arrow C, and when OFF (non-energized state), air circulation is prohibited. In addition, the air supply flow rate control valve 19 is turned ON.
In the state (energized), air flows through the orifice O as shown in Figure 4 (A), so the air flow rate is small and the O
In the FF state (non-energized), air flows through the orifice 0 and the large path as shown in FIG. 4(B), so the air flow rate increases.

34F is the lower arm 3 of the front right suspension of the vehicle.
5 and the vehicle body to detect the front vehicle height, and 34R is a rear vehicle height sensor installed 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. Signals detected by both vehicle height sensors 34F and 34R are supplied to a control unit 36 including a microcomputer.

38 is a vehicle speed sensor built into the speedometer, and supplies a detected vehicle speed signal to the control unit 36. 39 is an acceleration sensor that detects acceleration acting on the vehicle body, and supplies the detected acceleration signal to the control unit 36.

30 is a roll control mode selection switch that selects the roll control mode from SOFT, AUTO, and sport (5 PORTS), and 40 is a steering sensor that detects the rotational speed of the steering wheel 41, that is, the steering angular velocity. 42 is an accelerator opening sensor that detects the depression angle of an accelerator pedal of the engine (not shown). These roll control selection switch 30, sensor 4
The detected signals of 0 and 42 are sent to the control unit 36.
is supplied to

43 is a compressor relay for driving the compressor 11, and this compressor relay 43 is controlled by a control signal from the control unit 36. 4
4 is a high pressure switch that is turned on when the pressure in the high pressure reserve tank 15a falls below a second set value (for example, 9.5 Ky/cd), and a signal from this high pressure switch 44 is supplied to the control unit 36. Ru.

The compressor 11 is driven by a compressor relay 43 that is turned on by a signal from the control unit 36 when the pressure in the high-pressure reserve tank 15a falls below the second set value and the high-pressure switch 44 outputs an on signal. be done.

The compressor 11 also has a high pressure switch 44
When outputs an off signal, the compressor relay 43 is turned off by a signal from the control unit 36, and the compressor is stopped. As a result, the pressure within the high-pressure reserve tank 15a is always maintained above the second set value. In this case, even if the high pressure switch 44 is on, the low pressure switch 18 is on, that is, the return pump 16
The compressor 11 is configured to be prohibited from being driven when the compressor 11 is being driven. 45 is a pressure sensor provided in a passage that communicates the solenoid valves 26 and 27 with each other, and is connected to the rear suspension units R81 and R.
32 internal pressure is detected.

In addition, each solenoid valve 19.20.22.2 mentioned above
3.24.26.27.28.31 and 32 are controlled by control signals from a control unit 36.

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

This suspension device has an attitude control function.

That is, a description will be given of an attitude control function that suppresses attitude changes occurring in the vehicle body.

When the steering wheel 41 is steered to the right, the vehicle body tends to roll to the left. In response, the control unit 36 turns on the air supply solenoid valve 20.24 for a set period of time, and also turns on the right wheel solenoid valve 23.27.
is turned on, and after the set time has elapsed, the exhaust direction switching valve 32 is turned on. As a result, a set amount of compressed air is supplied from the high-pressure reserve tank 15a to each air spring chamber 3 of the left suspension units FS'1, R81, and the right suspension units FS2.
Low pressure reserve tank 15b from each air spring chamber 3 of R32
A set amount of compressed air is discharged.

This suppresses the displacement of the vehicle body from rolling to the left. In this state, a set amount of compressed air is supplied to each air spring chamber 3 of the left suspension unit FS2, R82, and the right suspension unit FS1
, R81, the state in which a set amount of compressed air is discharged from each air spring chamber 3 is maintained continuously. Then, when the turning operation shifts to straight-line operation and the control unit 36 detects that the steering becomes neutral by the steering sensor 40 or that the lateral acceleration decreases by the acceleration sensor 39, the control unit 36 activates the solenoid 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 maintained at the same pressure as before the start of control.

On the other hand, when the steering wheel 41 is steered to the left, the vehicle body tends to roll to the right. In response, the control unit 36 turns on the air supply solenoid valve 20.24 for a set time, and also turns on the left wheel solenoid valve 20.24.
2.26 is turned on, and after the set time has elapsed, the exhaust direction switching valve 32 is turned on. As a result, the right suspension unit FS2. Each air spring chamber 3 of RS2
A set amount of compressed air is supplied from the high pressure reserve tank 15a to the left suspension unit FS1,
Low pressure reserve tank 15b from each air spring chamber 3 of R81
A set amount of compressed air is discharged. This suppresses the displacement of the vehicle body from rolling to the right. Thereafter, the control is performed in the same manner as when the steering wheel 41 is turned to the right as described above.

Next, a description will be given of attitude control in the case of suppressing a nose dive in which the front part of the vehicle body sinks due to negative acceleration acting on the vehicle body when the brake is activated.

When the acceleration sensor 39 detects that negative acceleration in the longitudinal direction of the vehicle exceeds a set value, such as when the brakes are applied, the control unit 36 turns on the air intake solenoid valve 20 for a set time, and turns on 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 front wheel suspension unit FSI
A set amount of compressed air is supplied from the high pressure reserve tank 15a of the FS2, and a set amount of compressed air is discharged from the rear wheel suspension units R8I and R32 to the low pressure reserve tank 15b. In this way, the nose dive is suppressed. This state continues until the negative acceleration weakens.

Then, when the acceleration sensor 39 detects that the negative acceleration has weakened, the control unit 36 turns on the air intake solenoid valve 22.23 for a set period of time, and turns on the rear wheel solenoid valve 26.2.
Turn off 7. As a result, the low pressure reserve tank 15b is connected to the front suspension unit, FS1, FS2.
At the same time, a set amount of compressed air is discharged from the high-pressure reserve tank 15a to the rear wheel suspension units R31 and R82. In this way, each air spring chamber 3 of each suspension unit S is returned to the state before the start of control.

Next, a description will be given of attitude control in the case of suppressing a drift, in which the front part of the vehicle body rises and the rear part of the vehicle body sinks due to acceleration acting on the vehicle body when the vehicle starts and accelerates. When the accelerator opening sensor 43 or the acceleration sensor 39 detects that the vehicle is rapidly accelerating, the control unit 36 turns on the air intake solenoid valve 24 for a set period of time, turns on the front wheel solenoid valves 22 and 23, Further, after the set time has elapsed, the exhaust direction switching valve 32 is turned on. As a result, a set amount of compressed air is discharged from the front wheel suspension units FSI and FS2 to the low pressure reserve tank 15b, and a set amount of compressed air is supplied from the high pressure reserve tank 15a to the rear wheel suspension units R8I and R82. . In this way, the above-mentioned scattering is suppressed. This state continues until the acceleration weakens. Then, when the control unit 36 detects that the sudden acceleration has weakened by the accelerator opening sensor 42 or the acceleration sensor 39, the control unit 36 controls the intake solenoid valve 20 and the rear wheel solenoid valve 26. .27 is turned on for a set time, and the front wheel solenoid valves 22 and 23 are turned off. This results in
A set amount of compressed air is supplied from the high pressure reserve tank 15a to the front wheel suspension units FSI and FS2, and the rear wheel suspension units R8I and R82
A set amount of compressed air is discharged from the low pressure reserve tank 15b. In this way, each air spring chamber 3 of each suspension knee unit S is returned to the state before the start of control.

Here, to perform roll control or posture control of the vehicle body, the supply source of compressed air to the air spring chamber 3 of each suspension unit S is the high pressure reserve tank 15a, and conversely, the discharge destination is the low pressure reserve tank 15b. be. Therefore, the high pressure reserve tank 15a is set to a second set value (for example, 9.5 kg/cd) higher than the maximum control pressure value of the air spring chamber 3, and the low pressure reserve tank 15b is set to the same minimum control pressure value. It is necessary to maintain the pressure below a first set value (for example, 0.6 to 97 cd) that is lower than the pressure value. Each of these reserve tanks 15a.

The pressure holding operation for the compressor 15b is performed by the control unit 36 driving and controlling the compressor 11 and the return pump 16 in accordance with the tank internal pressure detected by the high pressure switch 44 and the low pressure switch 18, respectively.

Next, a description will be given of an abnormality detection operation of the low pressure switch 18 that is performed in conjunction with the above attitude control.

FIG. 5 is a flow chart showing abnormality detection processing of the low pressure switch 18 in the control unit 36. First, due to the attitude control, the air spring chamber 3 of the suspension unit S on the extension side is connected to the low pressure reserve tank 15.
This exhaust operation can be detected by checking whether any of the solenoid valves 22.2.3.26.27 is turned on. That is, the control unit 36 controls each solenoid valve 22°23.2.
It is detected from the valve control signal in response to 6.27 whether or not the exhaust operation associated with attitude control has started, and when the exhaust operation for the low pressure reserve tank 15b is started, the built-in exhaust operation detection counter CT is counted up (+1). (Steps Sl, S2). Here, low pressure pressure switch 1
8 is "ON", that is, the air spring chamber 3 of the compression side suspension unit S with respect to the low pressure reserve tank 15b.
With the exhaust operation, the tank internal pressure reaches the first set value (0.6K
g/cd), the exhaust operation detection counter CT is cleared and the low pressure switch 18 is cleared.
is determined to be normal.

On the other hand, for example, after the above steps Sl and S2, when the exhaust operation detection counter CT is 12, the low pressure pressure switch 1
8 is "OFF", that is, when it is determined that the internal pressure of the low pressure reserve tank 15b is maintained below the first set value, it is determined whether the value of the counter CT has reached "30" (step S3 → S5).In this step S5, rNOJ, that is, the rebound side suspension unit S
If the number of times it is determined that the internal pressure of the low pressure reserve tough 15b does not reach the first set value or more even if the air is exhausted from the air spring chamber 3 to the low pressure reserve tank 15b is less than 30, then the above procedure is repeated. The process returns to step S1, the exhaust control detection process.

After that, the process from step 81 to S3→S5 is repeated, and in step S5 the answer is "YES", that is, even though the exhaust control for the low pressure reserve tank 15b has been performed "30" times, the low pressure is higher than the first set value. Reserve tank 1
If it is determined that the internal pressure of 5b is not detected by the low pressure switch 18, it is determined that the low pressure switch 18 has a failure such as a disconnection, and the driver is notified of the switch abnormality by an alarm or the like (step S6). In addition, the control unit 36 forcibly drives the return pump 16, assuming that the internal pressure of the low pressure reserve tank 15b has clearly reached the first set value or more, for example, by detecting an abnormality in the low pressure switch 18, This prevents the low pressure reserve tank 15b from becoming high pressure. Therefore, it is possible to prevent the exhaust operation associated with attitude control from becoming difficult.

Therefore, according to the suspension device having the above configuration,
According to the amount of displacement of the vehicle body, compressed air is supplied to the air spring chamber 3 of the suspension unit S on the compression side, and air is exhausted from the air spring chamber 3 of the suspension unit S on the expansion side to perform anti-roll control or anti-nose dive control. Not only can posture control such as this be performed, but also an abnormal state of the low pressure switch 18 that monitors the internal pressure of the low pressure reserve tank 15b can be detected, and countermeasures such as alarm activation can be executed. - Therefore, it is possible to prevent a defective exhaust from the air spring chamber 3 to the low pressure reserve tank 15b, and to prevent a problem from occurring in posture control.

[Effects of the Invention] As described above, according to the present invention, a low pressure switch that is provided in a low pressure reserve tank and is activated when the tank internal pressure reaches a preset low pressure value or more, and an air spring chamber for attitude control are provided. a fluid discharge detection means for detecting a fluid discharge operation from the low pressure reserve tank; a counting means for counting the number of times the fluid discharge operation is detected by the fluid discharge detection means; and a counting means for counting the number of times the fluid discharge operation is detected by the fluid discharge detection means; The present invention includes a switch abnormality detecting means that detects an abnormality in the low pressure switch when the number of detected fluid discharge operations counted by the means reaches a predetermined number, so that abnormality in the low pressure switch can be immediately known. It is possible to provide a vehicle suspension device that can prevent the occurrence of attitude control problems.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a vehicle suspension device according to an embodiment of the present invention, and FIGS. 2 (A) and (B) respectively show the driven and non-driven states of the three-way valve in the vehicle suspension device. Figures 3(A) and 3(B) are diagrams showing the driven and non-driven states of the solenoid valve in the vehicle suspension system, respectively, and Figure 4(A).
) and (B) are diagrams showing the driving and non-driving states of the air supply flow rate control valve in the vehicle suspension system, respectively, and FIG. 5 is a flowchart showing the operation of the vehicle suspension 12232. FSI, FS2. R8I, R32... Suspension unit, 3... Air spring chamber, 4... Bellows, 1
DESCRIPTION OF SYMBOLS 1...Compressor, 15a...High pressure reserve tank, 15b...Low pressure reserve tank, 16...Return pump, 17...Return pump relay, 18.
・・Low pressure switch, 22.23, 26.27...
Solenoid valve, 28. 32... Exhaust direction switching valve, 36... Control unit, 38... Vehicle speed sensor, 43... Compressor relay, 44...
High pressure switch, CT...exhaust operation detection counter. Applicant's agent Patent attorney Takehiko Suzue Figure 2 (A) CB) Figure 3ffl Figure 4 Figure 5

Claims (1)

[Claims] It has an attitude control function that detects the amount of displacement that occurs in the vehicle body, supplies fluid from a high-pressure reserve tank to the fluid spring chamber of the suspension unit on the compression side, and discharges fluid from the fluid spring chamber of the suspension unit on the extension side to the low-pressure reserve tank. In a vehicle suspension system, a low pressure switch is provided in the low pressure reserve tank and is activated when the internal pressure of the tank reaches a preset low pressure value or higher, and a low pressure switch is provided in the low pressure reserve tank and operates when the tank internal pressure reaches a preset low pressure value, and a fluid is supplied from the air spring chamber to the low pressure reserve tank in connection with the above attitude control. a fluid discharge detection means for detecting a discharge operation; a counting means for counting the number of times the fluid discharge operation is detected by the fluid discharge detection means; and a fluid counted by the counting means while the low pressure switch remains inoperative. 1. A suspension device for a vehicle, comprising switch abnormality detection means for detecting an abnormality in the low pressure switch when the number of times the discharge operation is detected reaches a predetermined number.