JP3059199B2 - Electronically controlled hydraulic suspension - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vehicle height control system in which a fluid actuator such as a hydraulic cylinder is individually interposed between a vehicle body and each wheel, and a working fluid of the fluid actuator is controlled. An adjustable electronically controlled hydraulic suspension.

[Conventional technology]

Conventionally, suspensions equipped with various vehicle height adjustment devices have been used.
A suspension described in Japanese Patent No. 15109 is known.

The conventional suspension described in this publication, for a plurality of wheel positions, when the actual vehicle height value detected by each vehicle height sensor is higher than the target vehicle height region, lowers the vehicle height by discharging air from the air chamber of the suspension device, Conversely, when the actual vehicle height value is lower than the target vehicle height region, the vehicle height is increased by driving the compressor or supplying air from the reservoir tank to the air chamber, whereby the actual vehicle height values at a plurality of wheel positions are constantly It is designed to be within the target vehicle height range.

However, such a conventional vehicle height adjustment device controls an actuator such as an air chamber so that the road surface and the vehicle body are parallel to the last, and when the vehicle is stopped on a slope such as a slope or a sidewalk, The vehicle body posture becomes parallel to the inclined surface. This is not always a convenient posture, for example, when sleeping or working in a car.

Thus, a manually operated vehicle height adjustment device capable of leveling the floor surface of the vehicle body in an absolute space or adjusting the floor surface to an arbitrary angle when the vehicle is stopped can be considered. This vehicle height adjustment device is an indicator that can be operated when the occupant stops.
For example, a joystick switch (hereinafter, referred to as a joystick switch) is provided. The joystick switch outputs a signal corresponding to a single (for example, front left) or a plurality of (front wheel side, that is, front left, front right) wheel positions for which the vehicle height adjustment is desired in accordance with the operation, and this signal is output. The received control means, for example, supplies and discharges the working fluid to and from the fluid chamber at the designated wheel position, so that the vehicle height at the desired wheel position rises or falls, whereby the inclination of the vehicle body can be corrected by manual operation. (This is referred to as “4-axis vehicle height control”).

[Problems to be solved by the invention]

However, in the above-described vehicle height adjustment device, the eighth
As shown in FIG. 7A, for example, the vehicle is stopped on a stepped road between a sidewalk E and a road surface F having different heights on the left and right road surfaces, and the four-axis vehicle height control is performed so that the vehicle body B is horizontal in the absolute space. When returning to the running state, when the vehicle runs on the flat road F as shown by the imaginary line in FIG. 9, the vehicle height is set by the 4-axis vehicle height control while the vehicle is traveling on the sidewalk E. The state shifts from the state to the normal vehicle height control (the actual vehicle height value is automatically set to the target value). As a result, a relatively large change in the step may cause the step and the vehicle body B to interfere with each other as shown in FIG.

The present invention has been made in view of such an unsolved problem, and its purpose is to enable the floor surface of a vehicle body to be horizontal in absolute space or to be adjusted to an arbitrary angle, Even when the vehicle is started from a state in which the vehicle is stopped on an inclined road such as a stepped road and four-axis vehicle height control is performed, interference between the road surface and the vehicle body due to normal vehicle height control is prevented.

[Means for solving the problem]

In order to solve the above-mentioned problem, as shown in FIG. 1, a fluid actuator 100 which is individually interposed between a vehicle body and each wheel, and each fluid actuator 100 is connected to a fluid pressure source 101 as shown in FIG. In the electronically controlled hydraulic suspension including a switching mechanism 102 that is interposed in the flow path corresponding to each of the fluid actuators 100 and controls the flow of the working fluid, one wheel position or left / right or left / right or vehicle height adjustment is performed. An indicator 103 for manually instructing the front and rear two wheel positions and the vehicle height adjustment direction at the position, a stop determination unit 104 for determining a stop state, and the instruction when the stop determination unit 104 determines the stop state. A vehicle height individual changing means 105 for switching the state of the switching mechanism 102 corresponding to the wheel position indicated by the indicator 103 in the vehicle height adjustment direction indicated by the indicator 103; A travel determining means 106 determines the transition from the vehicle height changing state to the running state by the vehicle height individually changing means 105, the running determination means 1
06 determines the transition to the running state, the switching mechanism 10
2 and a vehicle height increase command means 107 for switching each of the two to a vehicle height increase state, and a vehicle height value which is increased by a command of the vehicle height increase instruction means 107 is increased to a constant value sufficiently higher than a target vehicle height value set during normal driving. When the vehicle has reached the position, each of the switching mechanisms 102 is switched to a position corresponding to the vehicle height, and the positions are maintained until the traveling determination unit determines that the vehicle has traveled on a flat road after determining the transition to the traveling state. And vehicle height maintenance command means 108.

[Action]

In the electronically controlled fluid pressure suspension of the present invention,
For example, suppose that the right wheel side is inclined in a low state when the left wheel rides on the sidewalk and stops, and the stop determination unit 104 determines the stop state. When the occupant instructs, for example, to increase the vehicle height on the right side of the vehicle body with the indicator 103, the individual vehicle height changing means 105 controls the switching mechanism 102 corresponding to the front right and rear right wheels, and the front right and rear right fluid actuators 100 For example, the working fluid is supplied from the fluid pressure source 101 to the vehicle, so that the stroke value of the fluid actuator 100 increases the vehicle height value on the right wheel side. Thereby, the degree of inclination of the vehicle body can be adjusted by the intention of the occupant, and for example, the vehicle body can be set to a horizontal horizontal position. This manual vehicle height control is
The same applies to the left and right two wheels or each wheel. When it is desired to lower the vehicle height, the direction indicated by the indicator 103 is set to the down side, so that each wheel or the front and rear,
The vehicle height of the left and right wheels goes down.

Further, when the vehicle height is changed by operating the individual vehicle height changing means 105 to start running, the running determination means 106 determines the start of the running. In response to this, the vehicle height increase instructing means 107 instructs an increase in the vehicle height at the four-wheel position,
When the vehicle height reaches a constant value sufficiently higher than the target vehicle height set during normal driving, the vehicle height maintenance command means 10
8 commands the maintenance of the vehicle height. This maintenance of the vehicle height value is continued by the vehicle height maintenance instruction means 108 until the vehicle comes out on a flat road.

For this reason, for example, from the state where the left wheel side is placed on a step like a sidewalk and manual vehicle level control is performed, while traveling with one wheel mounted on the step road, the vehicle height value is higher than usual. It has been evacuated to high values. Therefore, interference between the vehicle body and the road surface can be avoided.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 2 to 7 of the accompanying drawings. In this embodiment, a full hydropneumatic suspension which does not have an auxiliary spring such as a metal spring and receives a load by a force generated by a hydraulic cylinder is used.

In FIG. 2, 2FL to 2RR indicate front left to rear right wheels, 4 indicates a wheel side member, 6 indicates a vehicle body side member, and 8 indicates an electronic control hydraulic suspension (electronic control fluid pressure suspension).

The electronically controlled hydraulic suspension 8 includes a hydraulic pump 10 and an oil tank 12 serving as a hydraulic pressure source as a hydraulic pressure source, an accumulator 14, a check valve 16, and a hydraulic source side oil passage opening / closing unit disposed on the load side of the hydraulic pressure source. 18 and front and rear wheel side oil passage opening / closing sections 20F, 20R, variable suspension characteristic mechanisms 22FL-22RR installed for each wheel 2FL-2RR, hydraulic cylinders 24FL-24RR as fluid actuators, Up / down switch 25A for high control, joystick
It includes a switch 25B and a parking switch 25C, a sensor group including vehicle height sensors 26FL to 26RR, an acceleration sensor 28, and a vehicle speed sensor 29, and a controller 30 for arithmetic processing. In this embodiment, the up-down switch 25A and the joystick switch 25B constitute the indicator of the present invention.

Among them, the hydraulic pump 10 is configured by a tandem pump that rotates using the vehicle engine as a drive source, and that discharges hydraulic pressure to the power steering device and the hydraulic suspension 8. The suction side of the hydraulic pump 10 is connected to the oil tank 12 by a pipe 31, and the discharge side thereof is connected to a pipe 32. The load side of the pipe 32 is connected to the pulsation absorbing accumulator 14 and is connected to the hydraulic power source side oil passage opening / closing section 18 via the check valve 16.

The oil passage opening / closing section 18 is provided with an electromagnetically operated unload valve 34.
And a relief valve 36 having a predetermined relief valve pressure, and a flow divider 38 for distributing the oil passage to the front and rear wheels.
34, the relief valve 36, and each port on the hydraulic pressure source side of the flow divider 38 communicate with each other. Unloading valve 34, the control signals S ₁ to be supplied to the electromagnetic solenoid takes the communicating position when off,
Control signals S ₁ assumes a blocking position when on, always has an open structure. The tank-side ports of the unload valve 34 and the relief valve 36 are connected to the oil tank 12 by a pipe 40. A filter 42 for filtration is inserted in the middle of the pipe 40. Pipes are connected to the two ports on the load side of the shunt 38
The pipes 32F and 32R are connected to the front and rear oil passage opening / closing sections 20F and 20R, respectively.

The front wheel side oil passage opening / closing unit 20F includes a flow divider 42F having an input port connected to the pipe 32F at a position on the hydraulic pressure source side,
Flow limiting type check valves 44FL, 44
It is provided with FR, electromagnetically operated two-port switching valves 46FL, 46FR, 48F, and relief valves 50FL, 50FR. To elaborate on this,
The two load-side ports of the flow divider 42F are connected to one ends of pipes 32FL and 32FR corresponding to the front left and front right wheels, respectively. The other end of the pipe 32FL on the front left wheel side communicates with one port of another switching valve 48F via the check valve 44FL and the switching valve 46FL, and the high pressure side port of the relief valve 50FL. The suspension characteristics variable mechanism on the side reaches 22FL. Similarly, the other end of the pipe 32FR on the front right wheel side includes a check valve 44FR and a switching valve 46FR.
Through the other port of another switching valve 48F and the high pressure side port of the relief valve 50FR, and reaches the front left wheel side suspension characteristic variable mechanism 22FR.

The switching valve 46FL, which is inserted in series with each of the pipes 32FL, 32FR,
46FR is the control signal S ₂ to be supplied to the electromagnetic solenoid takes the blocking position due to the check valve incorporated in the off, the control signal S ₂ takes the communicating position when on, has a normally closed structure . Further, piping 32FL, also switching valve 48F that is interposed between 32FR, control signal S ₃ which is supplied to the electromagnetic solenoid takes the blocking position due to the check valve incorporated in the off, the control signal S ₃ is turned on It has a normally closed structure that sometimes takes a communicating position.

Further, the rear-wheel-side oil passage opening / closing section 20R is also provided with a flow divider 42R for diverting hydraulic oil to the rear left and rear right wheels, and a flow restriction type check valve 44.
RL, 44RR, electromagnetically operated two-port switching valves 46RL, 46RR, 48R, and relief valves 50RL, 50RR are provided, and are connected in the same manner as the front wheels via pipes 32RL, 32RR. Here, each of the relief valves 50FL to 50RR prevents an abnormal pressure increase on the load side, and is set to a predetermined relief pressure higher than a normally available pressure range. It is connected to the.

Each of the suspension characteristic variable mechanisms 22FL to 22RR is
Free piston type first and second accumulators 54 and 56 as gas springs, and a two-port switching valve 58 for varying the spring constant
And a variable throttle 60 that generates a damping force. A first accumulator 54 is directly connected to the pipe 32FL, a second accumulator 56 is connected via a switching valve 58, and a variable throttle 60FL is inserted in series with the pipe 32FL. Switching valve 58 that opens the motor 58A as an actuator, a closed position is switched, the motor 58A is rotated by a drive signal S _4. The wide of the flow path and is biased to the rotation of the variable throttle 60 is also motor 60A, the narrow is adjusted, the motor 60A so that the drive signal S ₅ is supplied.

Further, each of the hydraulic cylinders 24FL to 24RR has a cylinder tube 24a as shown in FIG. 2, and the cylinder tube 24a has a pressure chamber L separated by a piston 24b.
Are formed. Pipe 32FL (~ 32RR) in this pressure chamber L
Is connected. And the front wheel side hydraulic cylinder 24FL, 2
In the 4FR, the cylinder tube 24a is attached to the wheel-side member 4, and the end of the piston rod 24c is
On the other hand, on the contrary, rear wheel side hydraulic cylinder 24RL, 24R
In R, the cylinder tube 24a is attached to the vehicle body-side member 6, and the end of the piston rod 24c is attached to the wheel-side member 4.

On the other hand, the up-down switch 25A is constituted by a slide switch that takes two designated positions, up and down, and its output signal UD is "on" when in the up position and "off" when in the down position. The joystick switch 25B has a stick 25Ba that automatically returns to the center neutral position N, and can be freely turned in the radial direction from the neutral position N. As shown in FIG. Right side, back side, left side, front left side,
Eight directions, "front right", "rear right", and "rear left" can be indicated, and "JS ₁ ", "JS ₂ ",
“JS ₃ ”, “JS ₄ ”, “JS ₅ ”, “JS ₆ ”, “JS ₇ ”, “JS
Switch signal JS of S ₈ "is set to be obtained. Further, the parking switch 25C outputs a signal PK that is turned on only when the gear lever is at the parking position.

Further, the vehicle height sensors 26FL~26RR is constituted by a potentiometer or the like, mounted between the wheel-side member 4 and the vehicle body member 6, the vehicle height signal H _FL voltage value corresponding to the relative distance amount
HH _RR is output to the controller 30. The acceleration sensor 28 is mounted at a predetermined position on the vehicle body and acts on the vehicle body (width (vehicle width)).
A signal G corresponding to the direction and the longitudinal acceleration is output to the controller 30. The vehicle speed sensor 29 outputs a signal V corresponding to the vehicle speed to the controller 30, for example, by detecting the rotation speed of the output shaft of the transmission.

The controller 30, as shown in FIG. 4, vehicle height detection signal H _FL to H _RR to enter, and the gain adjuster 70 for gain multiplying the acceleration detection signal G, A digitizing the output of the gain adjuster 70 / D converter 72 and interface circuit 74 for inputting vehicle speed detection signal V and switch signals UD, JS, PK
And a microcomputer (CPU) 76 which takes in output signals of the A / D converter 72 and the interface circuit 74 and performs predetermined processing, and a drive which drives each solenoid and a motor according to a control signal outputted by the computer 76. Circuit 78
And The controller 30 includes a timer mechanism that keeps the power on for a predetermined time after the ignition switch is turned off.

The microcomputer 76 inputs the acceleration signal G based on a predetermined program stored in advance, adjusts the rotation of the motor 58A of the switching valve 58 and the motor 60A of the variable throttle 60, and changes the spring constant and the damping force according to the running state. In addition to inputting the vehicle height detection signals H _{FL to} H _RR and the vehicle speed signal V to perform conventional well-known vehicle height control for raising and lowering the average vehicle height value, FIG. 5 and FIG. The four-axis vehicle height control is performed in response to a manual operation command based on the processing in FIG.

 Next, the operation of this embodiment will be described.

First, the flowchart of FIGS. 5 and 6 executed by the controller 30 will be described. The process of FIG. 5 is performed as an interrupt routine in normal vehicle height control (for example, control described in Japanese Patent Application Laid-Open No. 63-154413). When the switch signal PK (interrupt signal) of the parking switch 25C is input, the normal vehicle height control is temporarily interrupted and executed. The process of FIG. 6 is executed as a subroutine during the execution of the process of FIG. 5, and shows a representative flow thereof. The controller 30 is started by turning on the ignition switch, starts the vehicle height control and the attitude control including the processing of FIG. 5, and continues the processing until the ignition switch is turned off.

In the step of FIG. 5, the microcomputer 76 of the controller 30 determines whether or not the vehicle is in a stopped state by checking whether or not the switch signal PK of the parking switch 25C is turned on.

When it is determined in this processing that the vehicle is in the stopped state in which the parking switch 25C is turned on, the process proceeds to step and the switch signal UD of the up / down switch 25A is input. Thereafter, the process proceeds to a step, and it is determined whether or not the read signal UD of the step is UD = ON corresponding to the increase in the vehicle height to determine whether or not the vehicle height is increased. In this judgment, "YE
When “S” is reached, the process proceeds to the step and the control signal S ₁ =
Is turned on, and the unload valve 34 is closed (cutoff position). Further, when the determination of “NO” is made in the step, the process proceeds to the step and the control signal S _{1 is} turned off, and
This brings the unload valve 34 into the open state (communication position).

When this step or the processing is completed, the process proceeds to the step, and the output signal JS of the joystick switch 25B is output.
After entering, move to the step. In the step, it is determined whether or not the stick 25Ba has been operated by checking whether or not the read signal of the step is JS = OFF corresponding to the neutral position N of the joystick switch 25B.

If the determination in this step is "NO", the process returns to the step assuming that the joystick switch 25B has not been operated. Among them, whether readings JS from the front side of the vehicle body up or down steps are commanded in step, it is determined by whether JS = JS _1. If "NO" in this step, JS determines whether or not the right
= Judged by whether JS ₂ or not. In the same manner, it is determined in step 1 whether or not a rear up or down command (JS = JS ₃ ) or a left up or down command (JS = JS ₄ ).

Further, if “NO” in the step, it is determined whether or not the front left up or down (JS = JS ₅ ) is instructed in the step. Similarly, in steps 1 to 5, whether or not the front right up or down command (JS = JS ₆ )
It is determined whether the rear right up or down command (JS = JS ₇ ) or not, and the rear left up or down command (JS = JS ₈ ).
If the answer is "NO" also in the step, it is determined that the position command is in a play state and the process returns to the step.

On the other hand, when the judgment of step is YES, the processing shifts to step and, respectively, and a subroutine process represented by FIG. 6 is performed.

Among them, a subroutine of steps intended to take place before the left switching valve 46FL, to the front right switching valve 46FR, the microcomputer 76, both switching valves 46FL in step of FIG. 6, the control for 46FR signals S _2, S Turn on only ₂ As a result, both switching valves 46FL and 46FR are opened,
The cylinder chamber L of the front hydraulic cylinders 24FL, 24FR communicates with the hydraulic pressure source.

Next, go to the step and select the joystick signal JS.
And then go to step. By checking whether or not the read value JS of the step has changed in this step, it is determined whether or not the stick position of the joystick switch 25B has been changed (including the neutral position N). If the determination is “NO”, it is determined that the vehicle body front side up or down is being continued, and the process returns to the step. "YE
In the case of "S", it is determined that the operation of raising or lowering the front side of the vehicle body is to be ended or stopped, and the process proceeds to step.

In the step, the front left switching valve 46FL, the front right switching valve 46F
The control signals S ₂ and S ₂ for R are turned off, whereby the two switching valves 46FL and 46FR are closed. For this reason, the cylinder chambers of the front left and front right hydraulic cylinders 24FL, 24FR and the hydraulic pressure source are shut off.

Thereafter, the microcomputer 76 returns the processing to the step of FIG. In the step, a flag F is set to indicate that the 4-axis vehicle height control has been performed, and thereafter, the process returns to the step.

Similarly, in the subroutine processing of the step of FIG. 5, the processing for the front right switching valve 46FR and the rear right switching valve 46RR is performed, the processing for the rear right switching valve 46RR and the rear left switching valve 46RL is performed in the step, and the processing for the rear right switching valve 46RL is performed in the step. The processing for the left switching valve 46RL and the front left switching valve 46FL is performed.

When the determination in step,, is "YES", the process proceeds to step,, respectively, and a subroutine process represented by FIG. 6 is performed. The subroutine processing of these steps,..., Is different from the subroutine processing of the above-described steps,.
Control of the front left switching valve 46FL in the step processing, control of the front right switching valve 46FR in the step processing, control of the rear right switching valve 46RR in the step, and control of the rear left switching valve 46RL in the step are performed in the same manner as described above.

On the other hand, "NO" in step mentioned above, that is, when it is determined that the running state, the process proceeds to step reads the vehicle speed detection signal V, and compares the read value with the reference value V _0. This reference value V ₀ is set near vehicle speed = 0.
In this step, the process returns to the step when the determination is “NO”, but shifts to the step when the determination is “YES”.

In the step, it is determined whether or not the flag F = 1. This determination is made in order to check whether or not the start of the travel is the travel after the vehicle height is set by the four-axis vehicle height control. For this reason,
If “NO” is determined in the step, the process returns to the step, and if “YES” is determined, the flag F is determined in the step.
After clearing, move to step.

In step turns on the control signal S _1, instructs the "closed" of the unloading valve 34. In the step, the control signal S ₂ ,
..., turn on the S _2, an instruction to "open" of the four-wheel electromagnetic switching valve 46FL~46RR. This allows the hydraulic oil to be
It flows into the cylinder chamber L of 24FL to 24RR, and the vehicle height increases. Next, the process proceeds to step S, where the vehicle height detection signals H of the four wheels are obtained.
Input _{FL to} H _RR, and read in steps H _{FL to} H
_RR is determined whether reaches the vehicle height reference value H _H. This vehicle height reference value H _H is sufficiently higher than the vehicle height target value H _N to be set in normal running. Therefore, to continue the vehicle height increases as does not reach the reference value H _H When the "NO" in step, when the "YES" four-wheel both as reaches the reference value H _H Step, the Transition.

In step sets the switching valve 46FL~46RR four-wheel each control signal S ₂ as an off to "closed", stop the vehicle height up.
Then in step to unload valve 34 in the "open" state turns off the control signal S _1.

Next, the microcomputer 76 proceeds to the step, and determines with a software timer whether or not a predetermined time T ₁ (for example, several seconds) has elapsed while keeping the vehicle height at H _H. This determination step is, after starting to drive,
The vehicle height control is not immediately shifted to, for example, the normal control in accordance with the vehicle speed V. The state in which the vehicle height is forcibly increased once is held for a certain period of time, and the state in which the vehicle is traveling on a stepped road or the like during that time is maintained. They try to overtake.

Therefore, when "YES" is determined in the step, the process proceeds to the step, and the vehicle height detection signals H _{FL to} H _RR are input, and the read values are stored as the vehicle height value.

Then, the process proceeds to the step, and the read value H of the step is obtained.
Based on the _{FL ~H RR, | H FR -H} FE | ≦ ΔH F and | H _RR -H _RL | ≦
It is determined whether ΔH _R or not. The process waits until the result of this determination becomes "YES", and then proceeds to the step after the wait.

In step switches the electromagnetic switching valve 46FL~46RR in the "open" state to turn on the control signal S ₂ again. Now that the unload valve 34 is in the open state, the hydraulic fluid is gradually discharged from each cylinder chamber L by the step command, and the vehicle height starts to decrease. Next, the vehicle height detection signals H _{FL to} H _RR are read in a step, and each vehicle height value H is read in a step.
_FL to H _RR determines whether decreased to the target value H _N in the normal ride height control. When the determination of “NO” is made in this step, the vehicle height is reduced continuously, and the process proceeds to the step when the determination of “YES” is made. And turning off the respective control signals S ₂ in step, switching the switching valve 46FL~46RR a "closed" state. Thus, the vehicle height down stops, vehicle height of each wheel is set to the reference value H _N substantially lower speed during normal running.

When the interrupt processing is completed in this manner, the microcomputer 76 returns the processing to the above-described main program for the normal vehicle height control.

In this embodiment, the unload valve 34 on the hydraulic power source side and the electromagnetic switching valve 46FL (-46RR) on each wheel load side correspond to the switching mechanism for each wheel of the present invention. Also a parking switch
25C and the processing of FIG. 5 step (including the interrupt processing based on the switch signal PK) form the stop determination means, and the interface circuit 74, the processing of FIG. And a vehicle speed sensor 29,
The interface circuit 74, the processing of steps 5 to 5 in FIG. 5 form travel determination means, the processing of step 5 in FIG. 5, and the drive circuit 78 form vehicle height increase command means, and the vehicle height sensors 26FL to 26RR, a gain adjuster. 70, the A / D converter 72, and the processing of steps 1 to 5 in FIG. 5 form the vehicle height maintenance command means.

 Next, the overall operation of the present embodiment will be described.

When the vehicle is in an idling state and is in a stopped state in which the parking switch 25C is turned on, the controller 3
The microcomputer 76 of 0 starts the processing of FIG. 5 relating to the 4-axis vehicle height control by interrupt processing from the normal vehicle height control.

Now, (in the figure using the Figure 8 the same reference numerals) Figure 7 (a) as shown in, stops rides the left wheel W _L side on the sidewalk E, and the vehicle body B and the right side down. In this state, if the occupant does not operate the joystick switch 25B, the microcomputer 76 executes the steps shown in FIG.
(The step is determined to be "NO") is repeated and the communication switching valves 48F and 48R at this time are closed.
At this time, when the indicated position of the up-down switch 25A is on the up side, the unload valve 34 is closed, the discharge pressure of the hydraulic pump 10 is supplied to the switching valves 46FL to 46RR in advance, and the standby state with respect to the vehicle height increase is performed. Becomes on the other hand,
When it is on the down side, the unload valve 34 is opened, whereby all the pump discharge oil flows into the tank 12 and the consumption flow rate decreases.

In this stopped state, to raise the vehicle height only on the right side of the vehicle body and take a substantially horizontal body posture in absolute space,
The occupant turns the up / down switch 25A up and puts the stick 25Ba of the joystick switch 25B to the “right” position. As a result, as described above, the unload valve 34 is closed first to be in the standby state. Thereafter, the microcomputer 76 shifts the processing from step 1 to step 5 in FIG. _2, and turns on the S _2. As a result, the switching valves 46FR and 46RR on the right wheel side are opened, and the hydraulic oil is supplied to the two hydraulic cylinders 24FR and 24RR on the right wheel side, and the vehicle height value on the right wheel side is proportional to the supply amount of the hydraulic oil. Rises.

Then, when the occupant releases the stick 25Ba when the vehicle body attitude is substantially horizontal, the stick 25Ba returns to the neutral position N by automatic return. When energized, the microcomputer 76 performs the process of FIG. 6, so that the right-wheel switching valves 46FR, 46RR are returned to the closed state, and the hydraulic oil of the hydraulic cylinders 24FR, 24RR is sealed. , The vehicle height at the time when the stick 25Ba is released.

To further correct the inclination of the vehicle body (for example, to lower the right wheel side), the up / down switch 25A may be slid to the down side, and the joystick switch 25B may be turned on again from the neutral position N to the “right” position. Thereby, the processing of FIG. 5 is repeated, the unload valve 34 is opened first, the corresponding switching valves 46FR, 46RR are opened, the hydraulic fluid of the cylinder is discharged, and the vehicle height at the designated wheel position is reached. Decrease. Then, when the operation of the joystick switch 25B is stopped when the vehicle body is lowered to the desired height, the vehicle body can take the desired height and inclination state.

Such manual control of the vehicle height value is the same for other wheel positions. For example, if the up-down switch 25A is set to the up side and the joystick switch 25B is in the "front side" position, the front left and front right hydraulic cylinders 24FL, Hydraulic oil is supplied to the 24FR and only the front side of the vehicle is raised. For example, if it is "front left", hydraulic oil is supplied (or discharged) only to the front left hydraulic cylinder 24FL, and the front left vehicle height value increases (or decreases).

After stopping on a slope or sidewalk in this way, the height and inclination of the vehicle body can be arbitrarily adjusted by manual operation, and naps and work in the vehicle are facilitated.

Further, after the vehicle is stopped on the sidewalk E, a substantially horizontal vehicle height value is set in the absolute space as shown in FIG. 7B by the four-axis vehicle height control according to the manual operation as described above (the vehicle height setting). After that, the same applies to the case where the engine is turned off), and it is assumed that traveling has started. Along with this, the microcomputer 76 of the controller 30 continues the processing of FIG. 5 or performs a new interrupt (at this time, the normal vehicle height control of the main program is temporarily suspended). That is, since it is determined as “NO” in the step of FIG. 5, the processing of steps 1 to 5 is performed.

As a result, when the vehicle speed reference value V ₀ is exceeded and the 4-axis vehicle height control has been performed (flag F = 1) before, first,
"Close" unload valve 34 and "open" switching valves 46FL-46RR
Is instructed to raise the vehicle height (step in FIG. 5,
). The vehicle height value of up, 4-wheel vehicle height is continued until the higher reference value H _H of, then posture of the vehicle height retention is taken (Fig step ~). When the vehicle height is increased, the vehicle body is substantially parallel to the inclination by the sidewalk E and higher than the normal vehicle height value as shown in FIG. 7 (c).

Thereafter, the predetermined time T ₁ is a four-wheel vehicle height is maintained by H _H (FIG step), during which will come off the flat road F finishing sidewalk traveling. That is, even when the sidewalk is forced to some extent or the vehicle descends from a high step due to road surface conditions, a sufficient margin is secured between the step, the protrusion, and the like and the vehicle body. Therefore, interference between obstacles such as steps and the vehicle body due to the shift to the normal vehicle height control immediately after the start of traveling as described above can be almost certainly avoided, and vehicle body damage can be prevented beforehand.

Furthermore, when as described above completes the vehicle height maintaining for a predetermined time T _1, looking at the left-right difference of the four-wheel vehicle height, gradually the four-wheel vehicle height to the target value H _N of a normal vehicle height when the difference between right and left thereof is small (From the fifth step), and thereafter, the routine shifts to the normal vehicle height control. Thus, while in the normal vehicle height control change vehicle height target value in accordance with the example the vehicle speed V, the front and rear adapted for fluid flow switching valve 48F, made to communicate with either 48R (on the control signal S _3), so-called 3 The actual vehicle height value is made to follow the target value in the point control state. The vehicle height up / down control is the same as described above.

On the other hand, assuming that the ignition switch is on, the controller 30 inputs a detection signal G of the acceleration sensor 28 based on a predetermined program, and when a predetermined roll condition, acceleration, or deceleration condition is satisfied, the gas spring constant is increased.
By controlling the electromagnetic switching valve 58 and the variable throttle 60 in the direction of the large damping force, the change of the vehicle body posture during traveling is suppressed, and when those conditions are not satisfied, the control is performed in the direction of the small gas spring constant and the small damping force. As a result, vibration transmitted from the road surface to the vehicle body is reduced, and riding comfort is improved.

In each of the above embodiments, the case where the working fluid is oil has been described. However, the present invention is not necessarily limited to this, and may be a gas having a low compression ratio.

Further, the fluid actuator of the present invention is not limited to the hydraulic cylinder described in the above-described embodiment, and for example, as described in JP-A-63-154413, an air chamber made of an elastic body is provided for each wheel in a suspension device. The configuration provided may be used.

Further, the switching mechanism of the present invention is not limited to the one constituted by the unload valve 34 and the two-port two-position electromagnetic switching valves 46FL to 46RR as described in the above-described embodiment. Instead of “communication to pump side”, “cut off”,
A three-port three-position solenoid-operated switching valve having a switching position for “communicating with the tank side” may be used for each wheel. Further, the vehicle height may be adjusted by controlling the operating pressure by using a pressure control valve capable of controlling the cylinder pressure in accordance with the control signal corresponding to each of the hydraulic cylinders 24FL to 24RR.

Furthermore, in addition to those in the vehicle height maintaining command means of the present invention described above, for example, attaching a pressure sensor for detecting the operating pressure of the hydraulic cylinders 24FL~24RR the pipe 32FL～32RR, after waiting for a predetermined time T ₁ as described above ( (See Fig. 5 step)
Next, as an alternative to the process of FIG. 5, the pressure detection signal of each pressure sensor is read, and it is determined whether or not the absolute value of the left-right difference between the front and rear wheels is smaller than a reference set value. When "YES" is reached, it is assumed that the left and right wheel loads are on the flat road due to the averaging direction, and the control may be shifted to the control for decreasing the vehicle height value as described in the above-described embodiment. According to this, together with waiting for a predetermined time T _1, certainly up vehicle height until it exits the flat road is maintained. Also, in such control, during the predetermined time T ₁ while a waiting vehicle height up state, in the standby, is determined on a flat road running by pressure detection described above, immediately when running on a flat road is determined The process may be shifted from the standby loop to the next step.

Furthermore, in addition to the control method by the individual vehicle height changing means of the present invention described in the above-described embodiment, the opening and closing of the communication switching valves 48F and 48R in FIG. 2 may be controlled together. That is, in the process of the step of FIG. 6, when the wheel position indicated by the joystick switch 25B is “front side”, the rear-wheel switching valve 48
R in the open state, in the case of `` rear side '', the front-wheel switching valve 48F is in the open state, and in the case of `` front left '' and `` front right, '' respectively, the rear-wheel switching valve 48R is in the open state, In the case of "rear left side" and "rear right side", the instruction to open the switching valve 48F on the front wheel side is performed together, and in the step, those switching valves 48F or 48R that are opened are combined. To return to the closed state. Thereby, the front wheel side or the rear wheel is used in the pitch operation mode in which the designated position is “front side” or “rear side”, or in the diagonal roll operation mode in which the designated position is “front left side” to “rear right side”. The left and right cylinder pressures on the wheel side are the same, and the increase or decrease of the vehicle height is a three-point control of the left and right wheel positions on the independent side and the left and right center position on the communication side. As a result,
Compared with the case where only the hydraulic oil of the cylinder to be raised or lowered is supplied and discharged as in the above-described embodiment, the ground reaction force (cylinder pressure) of the four wheels with respect to the vehicle center of gravity can be favorably bounced, The force can be settled easily. In the roll operation mode in which the designated position is “left” or “right”, the operation is the same as that described in the above-described embodiment.

Meanwhile, in the above embodiment, after the vehicle height is temporarily saved to a normal value higher than the time to lower the vehicle height to the target value H _N of the normal control, normal car and returns to this after the main program Although the height control is performed, for example, the vehicle height control may be immediately returned to the normal vehicle height control after the maintenance of the vehicle height, and the vehicle height reduction may be left to the normal vehicle height control.

〔The invention's effect〕

As described above, according to the present invention, when traveling from a state in which the vehicle height is changed by the individual vehicle height control (4-axis vehicle height control) of each wheel position by manual operation or front and rear or right and left two wheel positions, a flat road is used. The vehicle height at the four-wheel position is forcibly raised to a certain value until the vehicle goes out, so that the floor surface of the vehicle body can be leveled in absolute space or adjusted to an arbitrary angle. Furthermore, when the vehicle is stopped, the vehicle body attitude can be set according to the occupant's intention by the 4-axis vehicle height control, while at the start of traveling, a sufficient height is secured between the step and the like and the vehicle body. Accordingly, even when the vehicle travels on a step such as a sidewalk or descends from this step, interference between the step and the like and the vehicle body can be almost certainly avoided, and the vehicle body can be prevented from being damaged.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims, FIGS. 2 to 7 are views showing an embodiment of the present invention, FIG. 2 is a block diagram showing an overall configuration, and FIG. 3 is a pointing position of a joystick switch. FIG. 4 is a block diagram of the controller, FIG. 5 and FIG. 6 are schematic flowcharts showing a processing procedure of 4-axis vehicle height control executed by the controller in response to a manual operation, FIG. FIGS. 8 (a) to 8 (c) are diagrams showing examples of controlling the vehicle body posture, FIGS. 8 (a) and 8 (b) are explanatory diagrams each showing an example of control by a conventionally conceivable device, and FIG. It is. In the figure, 100: fluid actuator, 101: fluid pressure source,
102 ... switching mechanism, 103 ... indicator, 104 ... stop determination means, 105 ... vehicle height individual change means, 106 ... travel determination means,
107 vehicle height increase command means, 108 vehicle height maintenance command means, 4 wheel side member, 6 body side member, 8 electronically controlled hydraulic suspension, 10 hydraulic pump, 12 reservoir Tank, 24FL-24RR… Hydraulic cylinder, 25A… Up / down switch, 25B… Joystick switch, 25C… Parking switch, 30… Controller, 34… Unload valve, 46FL–46RR… Electromagnetic Switching valve.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomio Nakajima 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Yasuo Mori 2548 Tsuchida, Kani-shi, Gifu Pref. (72) Inventor Koji Takase 2548 Dota, Kagi City, Gifu Prefecture Kayaba Industry Co., Ltd.Gifu Kita Plant, Inc. (72) Inventor Kani Asahi 2548 Dota, Kani City, Gifu Prefecture Kayaba Industry Co., Ltd. Field (Int.Cl. ⁷ , DB name) B60G 17/015

Claims (1)

(57) [Claims] 1. A fluid actuator individually interposed between a vehicle body and each wheel, and each fluid actuator is interposed in a flow path connected to a fluid pressure source corresponding to each fluid actuator and operated. An electronically controlled fluid pressure suspension having a switching mechanism for controlling the flow of fluid, an indicator for manually instructing a one-wheel position for adjusting the vehicle height or a two-wheel position of left, right, front and rear, and a vehicle height adjusting direction at the position. And stop determination means for determining a stop state, and when the stop state is determined by the stop determination means, the state of the switching mechanism corresponding to the wheel position indicated by the indicator is indicated by the indicator. Individual height changing means for switching to the vehicle height adjusting direction, and determining a transition from a state in which the vehicle height has been changed by the individual height changing means to a traveling state. Traveling determination means, vehicle height increase instruction means for switching each of the switching mechanisms to a vehicle height increase state when the travel determination means determines transition to a traveling state, When the vehicle height value reaches a constant value sufficiently higher than the target vehicle height value set during normal traveling, each of the switching mechanisms is switched to a vehicle height holding state, and the traveling determination means makes a transition to a traveling state. An electronically controlled fluid pressure suspension comprising: vehicle height maintenance command means for maintaining the position from the determination to traveling on a flat road.