JPH04345512A - Height control device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a substantial difference in the internal pressure of each fluid chamber, even when the height of a vehicle is increased from extremely low level to proper level. CONSTITUTION:When rear side height HR for integrally controlling the internal pressure of right and left air chambers 3RR and 3RL is equal to or below the predetermined level, the air is fed to air chambers 3FR to 3RL, thereby performing control for increasing height. Thereafter, feed valves 13FR to 13RL are made continuous to each other for the predetermined time, thereby making the air chambers 3FR to 3RL continuous to each other. According to this construction, differential pressure is eliminated, because of the continuity of the chambers 3FR to 3RL, even if a difference is existing in internal pressure. Unstable state to support body weight actually at two points is, therefore, turned into stable state to support the weight at four points.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a vehicle height control device that controls vehicle height by adjusting the internal pressure of a fluid chamber interposed between a sprung mass and a sprung mass, and particularly relates to a vehicle height control device that controls vehicle height by adjusting the internal pressure of a fluid chamber interposed between a sprung mass and a sprung mass, particularly when the vehicle height is extremely low. Even when the vehicle height is raised to an appropriate height, the internal pressures of the fluid chambers do not vary greatly.

0002

2. Description of the Related Art As a conventional technique for controlling vehicle height by adjusting the internal pressure of a fluid chamber provided with a suspension, for example, the technique described in Japanese Patent Application Laid-open No. 82421/1983 is known. . This conventional vehicle height control device is a device that maintains an appropriate vehicle height by regulating the pressure in a fluid chamber interposed between a sprung mass and a sprung mass, and the fluid chamber is connected to a fluid pressure source or drain side. For example, each fluid chamber has a supply valve that communicates or shuts off between the two, and the vehicle height at three positions, for example, the vehicle height at the left and right wheel positions on the front wheel side and the vehicle height at the center part on the rear wheel side. is detected, and the internal pressure of the fluid chambers on the front wheel side is controlled individually on the left and right sides, and the internal pressure of the fluid chambers on the rear wheel side is controlled integrally on the left and right sides.By executing three-point control, the fine adjustment stage of vehicle height adjustment is performed. The hunting phenomenon was prevented.

0003

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, when raising the vehicle height, first, fluid is supplied to the left and right fluid chambers on the rear wheel side according to the vehicle height value on the rear wheel side. is supplied to raise the rear wheel side vehicle height, then fluid is supplied to the left and right fluid chambers of the front wheels according to the average vehicle height value of the front wheels to raise the front wheel side vehicle height, and finally, By finely adjusting the vehicle height difference by supplying and discharging fluid to the left and right fluid chambers on the front wheel side according to the vehicle height detection value, a horizontal vehicle posture is achieved within the appropriate vehicle height range. Therefore, if it takes a long time to supply fluid to the rear wheel fluid chamber, for example, when raising the vehicle height after the fluid in the rear wheel fluid chamber has completely drained, Even though they are integrally controlled, there is a risk that there will be a difference in internal pressure between the left and right fluid chambers on the rear wheel side.

[0004] Then, if the internal pressure of the front wheel side fluid chamber is adjusted with a difference remaining between the internal pressures of the left and right fluid chambers of the rear wheel side, the difference in the internal pressure of the left and right fluid chambers of the rear wheel side becomes diagonal. This appears as a difference between the internal pressures of the left and right fluid chambers on the front wheel side, so even if the vehicle is horizontal, the internal pressure of the two fluid chambers on one diagonal will be the same as that of the two fluid chambers on the other diagonal. This results in an unstable state where the pressure becomes higher than the internal pressure of the fluid chamber.

[0005] The present invention has been made by paying attention to the unresolved problems of the conventional technology, and it is possible to solve the problem in a situation where there is a difference in the internal pressure of the left and right fluid chambers that are integrally controlled. It is an object of the present invention to provide a vehicle height control device that can avoid the above-mentioned unstable situation even if the vehicle height control device exists.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a suspension including a fluid chamber disposed at each wheel position and capable of adjusting vehicle height by supplying and discharging fluid;
The vehicle height adjusting means has a supply valve disposed for each of the fluid chambers and adjusts the vehicle height by controlling the internal pressure of the fluid chambers, and the vehicle height adjusting means has supply valves disposed in each of the fluid chambers. In a vehicle height control device that integrally controls the internal pressure of one of the left and right fluid chambers, the vehicle determines whether the vehicle height of one of the front wheel side and the rear wheel side is less than or equal to a predetermined vehicle height. height determination means; and when the vehicle height determination means determines that the one vehicle height is less than or equal to the predetermined vehicle height, the Fluid chamber communication means is provided for communicating the fluid chambers with each other by setting the respective supply valves in a communicating state.

[0007]

[Operation] When the vehicle height determining means determines that the vehicle height of the front wheel side or the rear wheel side, the one whose internal pressure of the left and right fluid chambers is integrally controlled by the vehicle height adjusting means, is less than the predetermined vehicle height. Since it takes a long time to raise the vehicle height, it can be determined that there is a high possibility that a difference will occur between the internal pressures of the left and right fluid chambers after the control is completed.

When the vehicle height determination means makes such a determination, the fluid chamber communication means communicates each supply valve for a predetermined period of time after the vehicle height adjustment means completes the vehicle height adjustment. Since the fluid chambers are brought into communication with each other, even if a difference remains in the internal pressure of each fluid chamber, such difference in internal pressure is eliminated.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. In this embodiment, the vehicle height control device according to the present invention is
This is applied to a so-called air suspension in which an air chamber is interposed between the sprung mass and the unsprung mass. First, the configuration will be explained.

In FIG. 1, a front right wheel, a front left wheel, a rear right wheel,
Suspensions 1FR, 1FL,
1RR and 1RL are interposed, and each of these suspensions 1FR to 1RL includes shock absorbers 2FR to 2RL that generate damping force, and air chambers 3FR to 3RL as fluid chambers that support the static load of the vehicle body. have.

Each of the air chambers 3FR to 3RL is formed by an elastic body 4 made of, for example, rubber, which vertically expands and contracts between a vehicle body side member (not shown) and the shock absorbers 2FR to 2RL. Each of the air chambers 3FR and 3FL on the front side of the vehicle is provided with an electromagnetic switching type cut valve 11FR and 11FL, which maintains communication by the biasing force of a spring when a command signal is not supplied from a controller, which will be described later. An electromagnetic switching type supply valve 13FR that maintains the shutoff state by the biasing force of a spring when a command signal is not supplied from the controller.
, 13FL to a pipe line 7 leading to the discharge side of the compressor 5.

Similarly, the air chambers 3RR and 3RL on the rear side of the vehicle
Each of these is an electromagnetic switching type cut valve 11RR, 11R that maintains a communication state by the urging force of a spring when a command signal is not supplied from a controller to be described later.
A conduit 7 that leads to the discharge side of the compressor 5 via L and electromagnetic switching type supply valves 13RR and 13RL that maintain the shutoff state by the biasing force of a spring when a command signal is not supplied from a controller to be described later. It is connected to the.

Further, on the compressor 5 side of the cut valves 11FR to 11RL, an accumulator 1 is provided for adjusting the capacity of the air chambers 3FR to 3RL and changing the spring constant thereof.
7FR to 17RL are connected. That is, cut valve 1
If 1FR to 11RR are in communication, air chamber 3FR to
Since 3RL and the accumulators 17FR to 17RL are in communication, the expansion and contraction action of the accumulators 17FR to 17RL is added, and the spring constants of the air chambers 3FR to 3RL are in a small state, and conversely, the cut valves 11FR to 11RR are in a closed state. If there is, the air chambers 3FR to 3RL and the accumulators 17FR to 17RL are separated, so that the spring constants of the air chambers 3FR to 3RL are large.

The discharge side of the compressor 5 and the filter 9 are connected to the suction side of the compressor 5 via a return path 19, and no command signal is supplied to the return path 19 from a controller to be described later. In this case, an electromagnetic switching type exhaust valve 21 is installed which maintains the shut-off state by the biasing force of a spring. The compressor 5 is rotatably driven by receiving the output of an electric motor 23 connected to a power source such as a battery (not shown), and the electric motor 23 is operated in response to a command signal supplied from a controller to be described later. Or take a stopped state.

A controller 25 is provided for outputting command signals to each of the cut valves 11FR to 11RL, the supply valves 13FR to 13RL, the communication valve 15, the exhaust valve 21, and the electric motor 23. Microcomputer, interface circuit,
It consists of a storage device, etc. Furthermore, the controller 25 includes a vehicle height detection value HFR detected by a front right wheel vehicle height sensor 27 that detects the vehicle height of the right wheel position on the front side of the vehicle body, and a front left wheel vehicle height detection value HFR that detects the vehicle height of the left wheel position on the front side of the vehicle body. The vehicle height detection value HFL detected by the height sensor 29, the vehicle height detection value HR detected by the rear wheel height sensor 31 which detects the average vehicle height of the left and right wheel positions at the rear of the vehicle body, and the vehicle speed which detects the vehicle speed. The vehicle speed detection value V detected by the sensor 33 is supplied.

The front right wheel height sensor 27 and the front left wheel height sensor 29 are installed near the suspensions 1FR and 1FL, for example, and include a potentiometer or the like for detecting relative displacement between the vehicle body side member and the wheel side member. used. The rear wheel height sensor 31 may be a sensor such as a potentiometer that detects the relative displacement between the rear axle and the vehicle body side member, or if the vehicle uses a stabilizer, a sensor located in the center of the stabilizer. It is possible to use a sensor that detects the angle of rotation.

The controller 25 executes predetermined arithmetic processing based on the supplied detected values and signals and outputs a command signal, thereby adjusting the air pressure in each of the air chambers 3FR to 3RL and adjusting the vehicle height. control to keep the vehicle parallel to the road surface within the target vehicle height range. FIG. 2 is a flowchart showing an overview of the processing executed by the microcomputer in the controller 25, and the operation of this embodiment will be described below with reference to FIG.

First, in step 100, the vehicle height detection value HFR supplied from each vehicle height sensor 27, 29, 31 is
, HFL and HR, then step 10
1, and these vehicle height detection values HFR, HFL, HR
and the target vehicle height HOFR, HOF at each wheel position.
Based on L and HOR, the vehicle height deviations ΔHFR and ΔHFL at each wheel position are calculated according to the following formulas (1) to (3).
, ΔHR is calculated.

ΔHFR=HFR−HOFR

...(1) ΔHFL=HFL-HOFL

...(2) ΔHR =HR −HO
R
...(3) These vehicle height deviations ΔHF
Once R, ΔHFL, and ΔHR are calculated, step 10
2, it is determined whether the vehicle height deviation ΔHR on the rear wheel side is smaller than a predetermined value -H0 at which it can be determined that the vehicle height is extremely low.

Immediately after the start of control, the determination in step 102 is "
If “NO”, the vehicle height HR on the rear wheel side is the standard vehicle height HO.
Since this is higher than or slightly lower than R, it can be determined that there is little possibility that the difference in internal pressure between the air chambers 3FR and 3FL will become large after the vehicle height control is completed, and the process moves to step 103. In step 103, the determination in step 102 is “YES”.
”, it is determined whether the flag F that is raised is raised or not, but in step 1 immediately after the start of control
If the determination in step 02 is "NO", flag F remains lowered, so the determination in step 103 is "NO".
Then, the process moves to step 104.

Then, in step 104, the vehicle height deviation Δ
Air chamber 3FR to 3 depending on HFR, ΔHFL, ΔHR
By supplying air to RL or discharging air from air chambers 3FR to 3RL, the vehicle height at each wheel position is set to the target vehicle height HOFR,
Vehicle height control is executed to match HOFL and HOR (or to make the difference between them less than or equal to an allowable value). Specifically, first, air is supplied to the air chambers 3RR, 3RL according to the vehicle height deviation ΔHR on the rear wheel side, or air is supplied to the air chambers 3RR, 3RL.
Control is executed to exhaust air from RL and make the vehicle height deviation ΔHR zero.

For example, if the vehicle height deviation ΔHR is a positive value, this means that the vehicle height is too high, so the controller 25 stops the electric motor 23 and puts the compressor 5 into a non-driving state. And the front wheel side supply valve 13FR
, 13FL are cut off, while the supply valve 13 on the rear wheel side
The air in the air chambers 3RR and 3RL is discharged by putting the RR, 13RL and the exhaust valve 21 into communication.

Then, the internal pressure of the air chambers 3RR and 3RL decreases, and the vehicle height on the rear wheel side gradually decreases.
Adjust the rear wheel side to an appropriate vehicle height by repeating the process until it reaches zero or a sufficiently small value. Conversely, if the vehicle height deviation ΔHR is a negative value, it means that the vehicle height is lower.
The controller 25 outputs a command signal to the electric motor 23 to drive the compressor 5, and shuts off the front wheel side supply valves 13FR, 13FL and the exhaust valve 21, while the rear wheel side supply valves 13RR, 13RL is brought into communication, and air is supplied to the air chambers 3RR and 3RL.

[0024] Also in this case, since the vehicle height gradually rises,
By repeatedly performing steps 100, 101, and 104, the rear wheel side is adjusted to an appropriate vehicle height. When such rear wheel side vehicle height adjustment is completed, next, front wheel side vehicle height control is executed. Vehicle height control for the front wheels is performed in two stages. First, based on the average value of the left and right vehicle height deviations ΔHFR and ΔHFL, control is performed to raise or lower the overall vehicle height of the front wheels, similar to the vehicle height control of the rear wheels.

When the control for the entire front wheels is completed, the vehicle height control for the rear wheels is completed, and the tilt of the vehicle body in the pitch direction is eliminated. and,
After completing vehicle height control for the entire front wheel side, next
Based on the left and right vehicle height deviations ΔHFR and ΔHFL, the internal pressures of the air chambers 3FR and 3FL are adjusted to finely adjust the left and right vehicle height difference.

When the individual control of the left and right air chambers 3FR and 3FL is completed, the difference in vehicle height between the left and right front wheels disappears, and the inclination of the vehicle body in the roll direction is eliminated. As a result,
The vehicle height is adjusted to an appropriate value, and the tilt in the pitch direction and the tilt in the roll direction are eliminated, and the vehicle attitude becomes horizontal with respect to the road surface. On the other hand, the determination in step 102 is “Y
ES", the vehicle height on the rear wheel side is extremely low, and if the vehicle height is raised from this state, a relatively long time will be spent on control. etc. becomes so large that the left and right air chambers 3RR,
Since there is a high possibility that the difference in the internal pressures of 3RL will become large, the process moves to step 105, flag F is raised, and then the process moves to step 103.

Then, the subsequent determination at step 103 becomes ``YES'', so that step 103 does not directly proceed to step 104, but proceeds to step 106. Then, in step 106, it is determined whether or not the vehicle height control on the rear wheel side described above has been completed. If it is determined that the vehicle height control on the rear wheel side has not been completed, the process moves to step 104 and the above-described processing is executed.

Even after the process in step 104 is executed, flag F remains raised, so the subsequent determination in step 103 is ``YES'', and therefore, the determination in step 106 is repeated. And step 1
If it is determined that the process has been completed in step 06, step 10
7, it is determined whether or not the vehicle height control for the entire front wheel side described above has been completed. If it is determined that the vehicle height control has not been completed, the process advances to step 104.

If it is determined in step 107 that the control has been completed, the process proceeds to step 108, in which it is determined whether or not the individual control of the left and right air chambers 3FR and 3FL on the front wheel side is completed. If it is determined that the process has not been completed, the process moves to step 104. That is, when all the processes executed in step 104 are completed, the determinations in steps 106 to 108 all become "YES", and the processes after step 109 are executed.

That is, the flag F is lowered in step 109, and then the process proceeds to step 110, in which each air chamber 3FR is
~3RLs are communicated with each other for a predetermined period of time (for example, 60 seconds). Specifically, in step 110, the controller 25 stops the electric motor 23 to put the compressor 5 into a non-driving state, shuts off the exhaust valve 21, and sends a command signal to each of the supply valves 13FR to 13RL. By outputting and bringing these into communication state, the air chambers 3FR to 3RL are communicated with each other via the piping 7,
After a predetermined period of time has elapsed, each supply valve 13FR to 13RL is placed in a cutoff state.

As a result, when the process of step 110 is executed, even if a large difference remains in the internal pressures of the air chambers 3FR to 3RL upon completion of the vehicle height control executed in step 104, the air chambers 3FR to 3RL While the 3RLs are in communication with each other, the difference in internal pressure is eliminated, and the vehicle weight, which was supported by two points before step 110, is now supported by four points, so the vehicle is stabilized. It becomes a state.

Moreover, in this embodiment, there is no need to separately provide piping or valves for communicating or blocking the air chambers 3RR and 3RL on the rear wheel side, so a significant increase in cost can be achieved. There are no problems caused. Note that step 11
Even if the air moves between the air chambers 3FR to 3RL by executing process 0, the weight of the vehicle that was supported by two points will only be supported by four points, so the vehicle posture will not deteriorate significantly. , a small tilt of the vehicle is then performed in step 100,
If the processes 101 and 104 are executed, the problem can be easily resolved.

[0033] In this embodiment, the compressors 5,
The piping 7, the supply valves 13FR to 13RL, the exhaust valve 21, and the processing in step 104 correspond to the vehicle height adjustment means, the processing in step 102 corresponds to the vehicle height determination means, and the processing in step 106
The processing from step 110 corresponds to the fluid chamber communication means. In addition, in the above embodiment, the left and right air chambers 3FR on the front wheel side
, 3FL are individually controlled to eliminate the inclination of the vehicle in the roll direction.Instead, the internal pressures of the left and right air chambers 3RR and 3RL on the rear wheel side are individually controlled. You can.

Further, in the above embodiment, a case has been described in which air is used as the fluid, but the present invention is not limited to this, and it is also possible to use gases other than air, fluids, etc.

[0035]

[Effects of the Invention] As explained above, according to the present invention,
If a long time is spent controlling the vehicle height,
Since each supply valve is placed in communication for a predetermined period of time after the control ends, and the fluid chambers are communicated with each other, there is an effect that the vehicle can be kept in a stable state without causing a significant increase in cost.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an overview of processing executed within the controller.

[Explanation of symbols]

Claims (1)

[Claims] Claim 1: A suspension including a fluid chamber disposed at each wheel position and capable of adjusting the vehicle height by supplying and discharging fluid, and a supply valve disposed for each fluid chamber, and a suspension for controlling the vehicle height of the fluid chamber. and a vehicle height adjusting means for adjusting the vehicle height by controlling internal pressure, the vehicle height adjusting means integrally controlling the internal pressure of the left and right fluid chambers of one of the front wheel side and the rear wheel side. In the device, the vehicle height determining means determines whether the vehicle height of one of the front wheel side and the rear wheel side is less than or equal to a predetermined vehicle height; Fluid chamber communication means for communicating each of the supply valves and communicating the fluid chambers with each other for a predetermined period of time after the vehicle height adjustment by the vehicle height adjustment means is completed when it is determined that the vehicle height is lower than the vehicle height. A vehicle height control device comprising: