JPH06166315A - Suspension controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a suspension control device in which a switching valve does not switch even when oil leaks from a drain valve or the like. [Structure] A controller 20 is provided which opens the oil supply / drain valve 8 when the detected value of the main pressure sensor 17 provided in the main oil passage 6a is smaller than the reference value. When the oil pressure in the main oil passage 6a drops below the reference value, the controller 20 opens the oil supply / exhaust valve 8, and accordingly, the main oil passage 6a is supplied with pressurized oil from the cylinder 1 through the oil supply / exhaust valve 8. The main oil passage 6a that flows in and does not operate the pump 2
Keeps the oil pressure high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension controller for controlling the attitude of a four-wheeled vehicle.

[0002]

2. Description of the Related Art As a suspension control device of this type, the present applicant has already applied for a device disclosed in Japanese Patent Application No. 3-245069. In this technique, a cylinder connected to a pump via an oil supply / exhaust oil valve is interposed between the vehicle body and the axle side corresponding to each wheel, and a plurality of gas springs are connected to the cylinder.
A pilot type switching valve for switching the communication state between the plurality of gas springs is interposed, and the other end of the pilot pipe line, one end of which is connected to the switching valve, is connected to the oil between the pump and the oil supply / exhaust valve. The suspension control device is provided with an oil discharge valve connected to an oil passage between the pump and the oil supply / exhaust oil valve.

In this suspension control device, while the vehicle is not running, oil is supplied to and drained from the cylinder to adjust the vehicle height, and at the time of running, the pump is stopped and the oil supply / drain valve is closed. The valve is made to be filled with pressure oil in the cylinder side, and the impact of the vehicle body and the vibration of the vehicle body are suppressed by the cooperation of the cylinder and the gas spring. Further, when the oil supply / exhaust oil valve is closed, the oil exhaust valve is closed and the pump is operated to increase the pilot pressure, or the pump is stopped and the oil exhaust valve is opened. Thus, the pilot pressure is lowered and the communication state of the switching valve is switched and adjusted to adjust the spring constant of the entire gas spring.

[0004]

However, in the above-mentioned suspension control device, when the pilot pressure is high, oil liquid leaks from the oil discharge valve or the like to lower the pilot pressure, and the switching valve is unplanned accordingly. As a matter of course, there was a fear that the switching would occur.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a suspension control device in which the switching valve does not switch even when oil leaks from an oil discharge valve or the like.

[0006]

In order to achieve the above object, a cylinder connected to a pump between a vehicle body and an axle side corresponding to each wheel via a supply / drain oil valve. A plurality of gas springs are connected to the cylinder, and the communication state between the plurality of gas springs is switched between the plurality of gas springs when the pilot pressure is equal to or higher than a predetermined pressure. A switching valve is interposed, and the other end of the pilot pipe, one end of which is connected to the switching valve for guiding pilot pressure to the switching valve, is connected to an oil passage between the pump and the oil supply / exhaust valve.
A suspension provided with an oil discharge valve connected to an oil passage between the pump and the oil supply / exhaust oil valve, and further with control means for changing the pilot pressure by controlling the pump and the oil discharge valve. In the control device, a pressure sensor for detecting the pilot pressure of the switching valve is provided, and when the control unit controls the pilot pressure to be a reference value higher than the predetermined pressure, the detected value of the pressure sensor is A supply / exhaust oil valve control means for opening the supply / exhaust oil valve when it becomes smaller than the reference value is provided.

In order to achieve the above object, a second aspect of the present invention includes a cylinder connected between a vehicle body and an axle side corresponding to each wheel, the cylinder being connected to a pump via an oil supply / exhaust oil valve. A plurality of gas springs are connected to the cylinder, and a pilot type switching valve that switches the communication state between the plurality of gas springs when the pilot pressure is equal to or higher than a predetermined pressure is provided between the plurality of gas springs. Connecting the other end of a pilot line, one end of which is connected to the switching valve for guiding pilot pressure to the switching valve, to an oil line between the pump and the oil supply / exhaust oil valve, and In the suspension control device, an oil discharge valve is provided in connection with an oil passage between the oil discharge valve and the control means for changing pilot pressure by controlling the pump and the oil discharge valve. The pilot pressure from the predetermined pressure When and are controlled so that the reference value or more have, characterized in that a feed discharge valve time control means for opening the feed discharge valve in a predetermined cycle.

[0008]

Since the invention of claim 1 is configured as described above, when the control means controls the pilot pressure to a predetermined pressure or higher, the oil liquid leaks from the oil discharge valve or the like and the pilot pressure becomes the reference value. When it drops below, the oil supply / exhaust oil valve control means opens the oil supply / exhaust oil valve, and the pilot pressure is maintained at a high hydraulic pressure by the pressure oil flowing from the cylinder side through the oil supply / exhaust oil valve accordingly. .

Since the invention of claim 2 is configured as described above, when the control means controls the pilot pressure to be equal to or higher than a predetermined pressure, when the predetermined operation cycle elapses, the oil supply / exhaust oil valve time control means. Opens the oil supply / exhaust oil valve, and accordingly, the pilot pressure is maintained at a high hydraulic pressure by the pressure oil flowing from the cylinder side through the oil supply / exhaust oil valve.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A suspension control device according to an embodiment of the present invention will be described below with reference to FIGS. First, Fig. 1
The first embodiment of the present invention will be described with reference to FIGS.
In FIG. 1, a vehicle body (not shown) and wheels (not shown)
A total of four cylinders 1 (only one corresponding to one wheel is shown in FIG. 1) are interposed between the cylinder 1 and the side, and oil liquid (fluid It is possible to adjust the vehicle height by expanding and contracting by supplying and discharging.

A pump 2 is connected to the cylinder 1 through an oil passage.
Are connected. The pump 2 is driven by the electric motor 3,
The oil liquid stored in the reservoir tank 4 is sucked through the suction filter 5 to be pressurized and discharged as pressure oil to the cylinder 1 side. A check valve 7 and a supply / discharge oil valve 8 are provided in this order in an oil passage 6 connecting the pump 2 and the cylinder 1.

The first and second branch oil passages 9 and 10 are provided in the portion of the oil passage 6 where the check valve 7 and the oil supply / exhaust oil valve 8 are connected.
Are connected. The other end of the first branched oil passage 9 extends to the reservoir tank 4, and an electromagnetic switching type oil drain valve 11 that can be turned on / off (open / close) is provided in the middle. The oil discharge valve 11 is in the on (open) state so that the oil liquid is discharged to the reservoir tank 4 through the first branched oil passage 9 and is normally in the off (closed) state.

A third branch oil passage 12 is connected to a portion of the oil passage 6 that connects the cylinder 1 and the oil supply / exhaust valve 8. In the third branch oil passage 12, a cylinder pressure sensor 13 for detecting the internal pressure of the cylinder 1 and first and second gas springs 14 and 15 having damping force generating mechanisms 14a and 15a respectively composed of orifices or disk valves are provided. Are connected in this order. When the cylinder 1 expands and contracts, the first and second gas springs 14 and 15 absorb the force of the oil corresponding to the stroke thereof, and thus suppress the vibration of the vehicle body. The third branch oil passage 12 has an orifice portion 16a and a communication portion 16b at a portion between the first and second gas springs 14 and 15 so that the communication state can be switched by a predetermined pilot pressure or more and below. A pilot type switching valve 16 is provided.

The other end of the pilot pipe 16c, one end of which is connected to the switching valve 16, has a second end and a check valve 7 in the oil passage 6.
Between the branch oil passage 10 and the branch oil passage 10 (hereinafter referred to as main oil passage 6a)
In a normal state in which the hydraulic pressure of the main oil passage 6a (hereinafter referred to as the main pressure) is lower than a predetermined pressure, the pilot pressure applied to the switching valve 16 via the pilot pipe passage 16c becomes low, and the switching is performed. The valve 16 has the orifice portion 16a located in the third branch oil passage 12. As a result, the oil passage connecting the second gas spring 15 is almost shut off by the flow passage resistance of the orifice portion 16a, and the spring force and damping force for the cylinder 1 are generated only by the first gas spring 14 and are large. Generates spring force and high damping force. The orifice section 16
Although a may be a blocking part instead of the orifice part, when it is a blocking part, when the switching valve 16 is switched from the blocking state to the communicating state, the pressure of the first gas spring 14 and the second gas spring 15 is increased. Impact may occur because of the difference. Therefore, by using the orifice portion 16a as an orifice, the spring force and damping force of the first gas spring 14 can be reduced.
The second gas spring 15 and the second gas spring 15 are cut off from each other, and the pressure difference gradually disappears through the orifice.

When the main pressure increases, the pilot pressure applied to the switching valve 16 via the pilot pipe 16c also increases, and the switching valve 16 has the communicating portion 16b positioned in the third branch oil passage 12. As a result, the oil passage connecting the first gas spring 14 and the second gas spring 15 is in a communication state, and the spring force and the damping force on the cylinder 1 are both the first gas spring 14 and the second gas spring 15. Is generated in, generating a small spring force and a low damping force. A main pressure sensor 17 is provided in the main oil passage 6a, and in order to detect the pilot pressure, a main pressure that is the same as the pilot pressure is detected and output as a main pressure signal.

At the other end of the second branched oil passage 10, the cylinder 1, the cylinder pressure sensor 13, the oil supply / exhaust oil valve 8, the first and second gas springs 14 and 15 and the changeover configured as described above are provided. The valves 16 and the like are connected corresponding to the other three wheels in the same manner as shown in FIG. It should be noted that the illustration of devices provided at the other end of the second branched oil passage 10 is omitted.

A vehicle height sensor 18 for detecting the expansion / contraction amount of the cylinder 1 is provided between the vehicle body and each wheel, and detects the expansion / contraction amount of the cylinder 1 (that is, the vehicle height) and uses this as a vehicle height signal. It is designed to output. In the figure, 19 is a vehicle speed sensor for detecting the traveling speed of the vehicle.

A controller 20 which is connected to the electric motor 3, the oil drain valve 11, the oil supply / oil drain valve 8, the main pressure sensor 17, the cylinder pressure sensor 13, the vehicle height sensor 18 and the vehicle speed sensor 19 and serves as control means.
Is provided.

The controller 20 comprises a main control circuit 21 for carrying out the processing shown in FIG. 3, a memory 22, a main pressure judging means 23 and an oil supply / exhaust oil valve control means 24, and fulfills the functions described later. It is like this. The memory 22 stores a reference value i higher than the predetermined pressure used for comparison with the detection signal value (main pressure) from the main pressure sensor 17.

The main pressure judging means 23 judges whether the detection signal value (main pressure) from the main pressure sensor 17 is less than the reference value i, and outputs the judgment result signal to the oil supply / exhaust valve control means 24. To do. The oil supply / exhaust valve control means 24 inputs the determination result signal from the main pressure determination means 23 and controls the oil supply / exhaust valve 8 in cooperation with the main control circuit 21. In this suspension control device, the electric motor 3, the oil drain valve 11, and the oil supply / drain valve 8 are in the off state in the normal running state.

The control contents of the controller 20 will be described with reference to FIGS. 2 and 3. First, performs initialization by the power switch (not shown) is turned on (step S1), the control cycle t _ms elapsed whether determined (step S2), the determination is YES when has passed control cycle t _ms Proceed to step S3, and if NO is determined, step again
Judge S2.

In step S3, various signals are input, and in subsequent steps S4 and S5, a vehicle height determination subroutine and a spring / damping force switching subroutine are executed, respectively. The vehicle height determination subroutine is set to work only when the vehicle is not in the traveling state or is in the traveling state and the speed is extremely slow. Spring
A damping force switching subroutine is performed.

FIG. 3 shows the spring / damping force switching subroutine.
It will be described based on. In step S6, spring / damping force switching is performed based on a switch input (not shown), a detection signal of the vehicle speed sensor 19, and the like. In a succeeding step S7, it is determined whether or not the spring / damping force instruction is a soft instruction, that is, an instruction to position the communication portion 16b of the switching valve 16 in the third branch oil passage 12 is issued, and if YES is determined, the step is determined. Go to S8,
When it is determined to be NO, the process returns to the main routine.

In step S8, it is determined whether the detected value (main pressure) from the main pressure sensor 17 is less than the reference value i, and YES
If it is determined that the oil supply / drain valve 8 is turned on (opened) (step
S9) Return the process to the main routine. Also, in step S8
If NO is determined, the oil supply / drain valve 8 is maintained in that state (OFF state) (step S10).

The operation of the suspension control device configured as described above will be described. Normal electric motor 3 while the vehicle is running
Is off and the oil drain valve 11 and the oil supply / drain valve 8 are closed (off)
The pressure oil is sealed in the cylinder 1 side. The cylinder 1 and the gas spring cooperate to suppress the impact on the vehicle body, the vibration of the vehicle body, and the like, and the first and second gas springs are switched by switching the orifice portion 16a and the communication portion 16b of the switching valve 16. The spring constant of 14 and 15 and the damping force of the orifices 14a and 15a are adjusted.

Then, when the oil liquid leaks from the oil discharge valve 11 or the like during traveling, and the main pressure (= pilot pressure) decreases accordingly and becomes a value less than the reference value i, the controller 20 causes the oil supply / exhaust valve. 8 is turned on (open valve). Then, pressure oil flows from the cylinder 1 side into the main oil passage 6a side through the oil supply / exhaust oil valve 8, and the main oil passage 6a
6a hydraulic pressure becomes high. As a result, the switching operation of the switching valve 16 is not performed, and the switching valve 16 is maintained in a state where the orifice portion 16a communicates with the third oil passage 6 (step S10 in FIG. 3).
reference).

In this way, when the pilot pressure of the switching valve 16 is lowered due to leakage of oil liquid from the drain valve 11 or the like, the supply / drain valve 8 is opened by the operation of the controller 20 and the pilot pressure is immediately increased. Can be maintained above a predetermined pressure. As another method, when the pilot pressure is reduced, it is possible to maintain the pressure higher than a predetermined pressure by operating the pump 2 again. However, according to the first embodiment, the pump 2 is operated. This eliminates the need for the pump 2 and reduces the frequency of operation of the pump 2, which improves the durability of the pump 2 and reduces the frequency of operating noise of the pump 2.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. The controller 20
In place of the memory 22, the main pressure determining means 23 and the oil supply / exhaust oil valve control means 24 in FIG. 1, a counter 40, a cycle determining means 41, and a cycle determining means 41, which count an operation cycle based on a control cycle t _ms Memory 4 that stores the reference cycle used for judgment
2, and the oil supply / drain valve control means 43 is provided.

The cycle determining means 41 determines whether the operating cycle from the counter 40 has reached the reference cycle. The oil supply / exhaust oil valve control means 43 cooperates with the main control circuit 21 to open the oil supply / exhaust oil valve 8 by inputting the determination result signal indicating that the operation cycle has reached the reference cycle from the cycle determination means 41. The valve operates.

In the suspension control device configured as described above, the counter 40, the cycle determination means 41, the memory 42, the oil supply / exhaust oil valve control means 43, and the main control each time the operation cycle reaches the reference cycle during traveling. Controller 20 with circuit 21
Turns on (opens) the oil supply / drain valve 8. Then, pressure oil flows into the main oil passage 6a from the cylinder 1 side through the oil supply / exhaust valve 8, and the main pressure (= pilot pressure) of the main oil passage 6a is maintained at a high value. As a result, the switching operation of the switching valve 16 is not performed, and the switching valve 16 maintains the state in which the orifice portion 16a is located in the third oil passage 6.

As described above, the oil supply / drain valve 8 is provided every predetermined operation cycle.
The valve can be opened to maintain the pilot pressure at a predetermined pressure. In order to maintain the pilot pressure, as another method, it is possible to maintain the pressure equal to or higher than the predetermined pressure by operating the pump 2 at predetermined intervals. However, according to the second embodiment described above, Since the operation does not have to be performed, the frequency of operation of the pump 2 is reduced, which improves the durability of the pump 2 and reduces the frequency of occurrence of operating noise of the pump 2.

[0032]

According to the invention of claim 1, when the pilot pressure is controlled to a predetermined pressure or higher by the control means and the pilot pressure falls below a reference value, the oil supply / discharge oil valve control means controls By opening the oil valve and maintaining the pilot pressure high, it is possible to maintain the oil pressure in the oil passage above a certain level, and the switching valve shuts off unexpectedly due to leakage of oil liquid from the oil discharge valve, etc. It is possible to prevent replacement.

Since the invention of claim 2 is configured as described above, when the control means controls the pilot pressure to be equal to or higher than a predetermined pressure, when a predetermined operation cycle elapses,
The oil supply / exhaust oil valve time control means opens the oil supply / exhaust oil valve to maintain the pilot pressure high, and it is possible to maintain the pilot pressure above a predetermined pressure. It is possible to prevent the switching valve from being switched unexpectedly.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a suspension control device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a main routine in control contents of a controller of the suspension control device.

FIG. 3 is a flowchart showing a spring / damping force switching subroutine in the control content of the controller of the suspension control device.

FIG. 4 is a diagram schematically showing a suspension control device of a second embodiment of the present invention.

[Explanation of symbols]

 1 cylinder 2 pump 8 oil supply / drain valve 11 oil drain valve 14 first gas spring 15 second gas spring 16 switching valve 16a orifice part 16b communication part 16c pilot line 17 main pressure sensor 20 controller (control means) 21 main Control circuit 23 Main pressure determination means 24 Supply / drain valve control means

Claims (2)

[Claims] 1. A cylinder connected to a pump via an oil supply / drain valve is provided between a vehicle body and an axle side corresponding to each wheel, and a plurality of gas springs are connected to the cylinder. A pilot type switching valve that switches the communication state between the plurality of gas springs when the pilot pressure is equal to or higher than a predetermined pressure is provided between the individual gas springs, and the switching is performed to guide the pilot pressure to the switching valves. The other end of the pilot conduit, one end of which is connected to the valve, is connected to the oil passage between the pump and the oil supply / exhaust oil valve, and is connected to the oil passage between the pump and the oil supply / exhaust valve. In a suspension control device provided with an oil drain valve and further with control means for changing pilot pressure by controlling the pump and the oil drain valve, a pressure sensor for detecting pilot pressure of the switching valve is provided, and The pilot pressure is controlled by the control means. A supply / exhaust oil valve control means is provided for opening the supply / exhaust oil valve when the detected value of the pressure sensor becomes smaller than the reference value while controlling to be equal to or higher than a reference value higher than a constant pressure. A suspension control device characterized by the above. 2. A cylinder connected to a pump via an oil supply / exhaust oil valve is provided between the vehicle body and the axle side corresponding to each wheel, and a plurality of gas springs are connected to the cylinder. A pilot type switching valve that switches the communication state between the plurality of gas springs when the pilot pressure is equal to or higher than a predetermined pressure is provided between the individual gas springs, and the switching is performed to guide the pilot pressure to the switching valves. The other end of the pilot conduit, one end of which is connected to the valve, is connected to the oil passage between the pump and the oil supply / exhaust oil valve, and is connected to the oil passage between the pump and the oil supply / exhaust valve. In a suspension control device provided with an oil drain valve and further with control means for changing the pilot pressure by controlling the pump and the oil drain valve, the control means sets the pilot pressure to a reference value higher than the predetermined pressure. When controlling so that A suspension control device comprising a supply / exhaust oil valve time control means for opening the supply / exhaust oil valve at regular intervals.