JPH08258532A - Damping force controller - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent pressure drop in the line passage without providing pressurizing means. A back pressure valve 62 is provided in a return path 42 from a hydraulic pump 38 for power steering to a reservoir tank 41, and an accumulator 61 is provided in a flow path 45 connected to a second return path 46 so that a pressure from the return path 45 side is provided. The oil is allowed to flow to the side of the return path 42 only when the oil becomes a predetermined value or more, and the inside of the second return path 46 is pressurized without constantly pressurizing the inside of the pipe. The pressure oil is accumulated by the accumulator 61, the pressure in the reservoir tank 41 is increased, and the oil in the check valve 47 is surely flowed in without constantly pressurizing the inside of the pipe to generate bubbles in the pipe. Without providing a large-scale pressurizing means in the reservoir tank 41 or firmly fixing the pipe, the hydraulic pump 38 can be operated without affecting the hydraulic system for power steering. The pressure drop in the line passage 43 is prevented regardless of the rolling state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force control device that absorbs a relative posture change between two members, and is particularly suitable for application to a suspension device in an automobile.

[0002]

2. Description of the Related Art As a suspension system (suspension) for supporting a vehicle body of an automobile, an actuator is interposed between the vehicle body side and the wheel side, and the actuator is positively controlled by operating the actuator according to a change in the posture of the vehicle body. A suspension that is designed to shake is known. A conventional suspension will be described with reference to FIG. FIG. 2 shows a hydraulic circuit state of an actuator in a conventional suspension.

A main body 2 of the actuator 1 is attached to a vehicle body side (not shown), and a movable portion 4 which is movable with respect to the body 2 via a piston rod 3 is attached to a wheel side (not shown). When the pressure oil is supplied to the first hydraulic chamber 5 of the actuator 1 and the pressure oil is discharged from the second hydraulic chamber 6, the movable portion 4 moves upward in the figure via the piston rod 3, and conversely, When the pressure oil is supplied to the second hydraulic chamber 6 and the pressure oil is discharged from the first hydraulic chamber 5, the movable portion 4 moves downward in the figure via the piston rod 3. A compression coil spring 7 is provided between the main body 2 of the actuator 1 and the movable portion 4, and the compression coil spring 7 urges the movable portion 4 downward in the figure to support a 1G load of a vehicle body (not shown). There is.

On the other hand, a hydraulic pump 8 for power steering is connected to an engine (not shown), and a part of the pressure oil generated by driving the hydraulic pump 8 is sent to the actuator 1 via a priority valve 9. There is. A switching valve 10 is provided between the priority valve 9 and the actuator 1, and a pressure oil flow path is provided in a return path 12 to the reservoir tank 11 and a line path 13 connected to the actuator 1 side by turning the switching valve 10 on and off. Are switched. That is, when the switching valve 10 is turned off (state shown in the drawing), the pressure oil from the priority valve 9 is sent to the return path 12 and returned to the reservoir tank 11. Also,
When the switching valve 10 is turned on, the pressure oil from the priority valve 9 is sent to the line passage 13.

An electromagnetic pressure control valve 14 is provided in the line passage 13, and the line passage 13 is connected to the first hydraulic chamber 5 and the second hydraulic chamber 6 of the actuator 1 via the electromagnetic pressure control valve 14. The electromagnetic pressure control valve 14 has a structure in which a thrust force proportional to the current is generated by the solenoid, and the spool stops at a position where the spool balances the output pressure. Therefore, it is possible to generate a pressure according to the command signal, and the first pressure can be generated at an arbitrary pressure.
Sending pressure oil to the hydraulic chamber 5 or the second hydraulic chamber 6,
Pressure oil can be circulated between the hydraulic chamber 5 and the second hydraulic chamber 6.

The discharge port of the electromagnetic pressure control valve 14 is the flow path 1
5 is connected to the return path 12 by the electromagnetic pressure control valve 14
A second return path 16 is provided branching from each line path 13 on the wake side. Each second return path 16 merges with the flow path 15, and the second return path 16 is in a state of being connected to the return path 12. Each second return path 16 has a flow path 1
When the check valves 17 that allow the oil to flow from only the 5 side (only from the return path 12 side) are respectively provided and the pressure in the first hydraulic chamber 5 or the second hydraulic chamber 6 becomes relatively low The oil from the return passage 12 side flows into the line passage 13 in accordance with the pressure difference.

The reservoir tank 11 is provided with a sealing lid 18, and the oil in the reservoir tank 11 is sealed by the sealing lid 18. The enclosing lid 18 is provided with a pressurizing device 19, and the inside of the reservoir tank 11 and the inside of the flow path connected to the reservoir tank 11 are pressurized with a predetermined pressure.
In the drawings, reference numeral 20 is a return pipe from a power steering device (not shown), and 21 is an oil return pipe for the sliding portion of the actuator 1. The sealing lid 18 and each pipe are fixed with a sufficient attachment force against the pressure applied by the pressurizing device 19.

In the conventional suspension described above, the switching valve 10 is turned off during normal traveling and the hydraulic pump 8 is
The pressure oil from 1 is returned to the reservoir tank 11 through the return path 12. In this state, if there is an input from the wheel side due to the unevenness of the road surface, the movable portion 4 of the actuator 1 will move to the main body 2
And moves up and down with respect to each other, and oil flows between the first hydraulic chamber 5 and the second hydraulic chamber 6 via the electromagnetic pressure control valve 14. This time,
The flow resistance of the oil discharged from the hydraulic chamber on the side compressed by the set pressure of the electromagnetic pressure control valve 14 is adjusted, and the input from the wheel side is attenuated by the actuator 1.
When the predetermined posture control conditions (during braking or turning) are satisfied, the switching valve 10 is turned on and the posture control by the actuator 1 is executed. That is, the hydraulic pump 8
Is sent to the electromagnetic pressure control valve 14, and for example, a predetermined pressure oil flows into the first hydraulic chamber 5 and the second hydraulic chamber 6
The pressure oil is discharged from the vehicle, and the movable portion 4 is positively raised with respect to the main body 2 to suppress the leaning of the vehicle body.

In the suspension described above, the switching valve 10
Is off, the input from the wheel side is attenuated by the actuator 1 by the set pressure of the electromagnetic pressure control valve 14. Therefore, continuous input from the wheel side due to unevenness of the road surface results in continuous reciprocating motion of the movable portion 4, and oil discharged from one hydraulic chamber passes through the electromagnetic pressure control valve 14 and enters the other hydraulic chamber. The flow is repeated. If the continuous reciprocating movement of the movable part 4 becomes faster, the pressure on the inflow side may be reduced to a negative pressure. However, when the pressure is reduced, the oil on the reservoir tank 11 side from the check valve 17 may become the second pressure. It is designed to flow into the return path 17. Since the inside of the reservoir tank 11 is pressurized by the pressurizing device 19, even if the movable portion 4 continuously reciprocates fairly quickly, the inflow of the oil from the check valve 17 is reliably performed, and the inflow side has a negative pressure. No air bubbles will be generated in the pipe.

[0010]

In the conventional suspension, the interior of the reservoir tank 11 is pressurized by the pressurizing device 19, so the interior of the pipe is pressurized and the actuator 1
Even if the reciprocating movement of the movable part 4 continues, there is no possibility that bubbles will be generated in the pipe. However, since the inside of the reservoir tank 11 is pressurized, it is necessary to seal the reservoir tank 11 and the pipe connection portion with a fixing force according to the pressurized state. Therefore, the reservoir tank 11 and the pipe connecting portion are large-scaled, and the cost and the labor for mounting are required. In particular, when the operating hydraulic pressure of the actuator 1 is obtained from the hydraulic pump 8 for power steering, the connection of the return pipe 20 from the power steering device must be strengthened. It will affect you.

Further, due to the temperature change, the reservoir tank 1
When the temperature of the oil sealed inside 1 rises, the liquid level of the reservoir tank 11 changes due to the expansion of the oil, causing a pressure fluctuation, and the oil pressure equivalently increases. For this reason,
In consideration of this point, it was necessary to strengthen the reservoir tank 11 and the pipe connection. Furthermore, when maintenance such as replenishment of oil into the reservoir tank 11 is performed, it is necessary to reconnect the pipes and pressurize the inside of the reservoir tank 11, which results in very poor maintainability.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a damping force control device that prevents a pressure drop in a pipe without pressurizing the hydraulic path.

[0013]

The structure of the present invention for achieving the above object comprises a double-acting actuator which is interposed between two members and absorbs a relative change in posture between the two members. A hydraulic pump for supplying pressure oil to the actuator, and a switching valve provided between the actuator and the hydraulic pump for switching the pressure oil flow path to a return path to a reservoir tank and a line path connected to the actuator side. And 2 of the actuator provided in the line path
A control valve for controlling the hydraulic pressure in one hydraulic chamber, a second return path branched from the line path on the downstream side of the control valve and joined with the return path, and provided in the middle of the second return path A check valve that allows oil to flow only from the return path side and a return valve provided between the return path and the reservoir tank only when the oil pressure from the return path side becomes a predetermined value or more. From the reservoir tank to the reservoir tank side.

Further, the structure of the present invention for achieving the above object includes a double-acting type actuator which is interposed between two members and absorbs a relative posture change between the two members, and the actuator. A hydraulic pump that supplies pressure oil,
A switching valve provided between the actuator and the hydraulic pump to switch the flow path of the pressure oil to a return path to the reservoir tank and a line path connected to the actuator side; and two actuators provided on the line path. A control valve for controlling the hydraulic pressure in the hydraulic chamber, a second return path that branches from the line path on the downstream side of the control valve and joins with the return path, and a second return path are provided in the middle of the second return path. A check valve that allows oil to flow only from the return path side and a second return path that is closer to the return path than the check valve, and is provided in the second return path, and accumulates the hydraulic pressure in the second return path. It is provided between the accumulator and the return passage and the reservoir tank, and allows the oil to flow from the return passage side to the reservoir tank side only when the oil pressure from the return passage side exceeds a predetermined value. Characterized in that a back pressure valve for.

Further, the structure of the present invention for achieving the above object is a double-acting type actuator which is interposed between two members and absorbs a relative posture change between the two members, and the actuator and A hydraulic pump that divides and supplies the pressure oil to another hydraulic system, a flow path of the pressure oil that is provided between the actuator and the hydraulic pump, and a return path to the reservoir tank and a line path that connects to the actuator side. Switching valve, a control valve provided in the line passage for controlling the hydraulic pressure in the two hydraulic chambers of the actuator, and branched from the line passage on the downstream side of the control valve and joined with the return passage. The second return path and the second
A check valve that is provided in the middle of the return path and allows oil to flow only from the return path side, and a hydraulic pressure from the return path side that is provided between the return path and the reservoir tank exceeds a predetermined value. And a back pressure valve that allows the oil to flow from the return path side to the reservoir tank side only in the case of the above.

Further, the structure of the present invention for achieving the above object is a double-acting type actuator which is interposed between two members and absorbs a relative posture change between the two members, and the actuator and A hydraulic pump that divides and supplies the pressure oil to another hydraulic system, a flow path of the pressure oil that is provided between the actuator and the hydraulic pump, and a return path to the reservoir tank and a line path that connects to the actuator side. Switching valve, a control valve provided in the line passage for controlling the hydraulic pressure in the two hydraulic chambers of the actuator, and branched from the line passage on the downstream side of the control valve and joined with the return passage. The second return path and the second
A check valve that is provided in the middle of the return path and allows oil to flow only from the return path side; and a second return path that is provided on the second return path on the confluence side of the return path with respect to the check valve. An accumulator for accumulating the hydraulic pressure in the return path, and a return path side to the reservoir tank side provided only when the hydraulic pressure from the return path side provided between the return path and the reservoir tank exceeds a predetermined value. And a back pressure valve that allows the oil to flow therethrough.

The two members are a vehicle body side and a wheel side of an automobile, and the actuator is a damper of a suspension device for supporting the vehicle body. Further, the two members are a vehicle body side and a wheel side of an automobile, the actuator is a damper of a suspension device for supporting the vehicle body, and the other hydraulic system is a hydraulic pressure of a power steering device that assists a steering force of steering. It is characterized by being a system.

[0018]

In the first aspect of the invention, when the flow path of the pressure oil is switched to the line path by the control valve, the actuator is operated by the pressure oil supplied by the hydraulic pump, and the relative posture between the two members is maintained. Is actively controlled. Further, when the flow path of the pressure oil is switched to the return path to the reservoir tank by the control valve, if a relative posture change occurs between the two members, the oil flow between the two hydraulic chambers of the actuator is controlled by the control valve. Done through. Even if the pressure in the line passage on the oil inlet side decreases due to continuous posture change, the back pressure valve keeps the second return passage pressurized to a predetermined pressure. Through this, the oil in the second return passage surely flows into the inlet side line passage.

In the second aspect of the invention, when the flow path of the pressure oil is switched to the line path by the control valve, the actuator is operated by the pressure oil supplied by the hydraulic pump,
The state of the relative posture between the two members is actively controlled.
Further, when the flow path of the pressure oil is switched to the return path to the reservoir tank by the control valve, if a relative posture change occurs between the two members, the oil flow between the two hydraulic chambers of the actuator is controlled by the control valve. Done through. Even if the pressure in the line passage on the oil inlet side decreases due to continuous posture change, the back pressure valve and accumulator keep the second return passage pressurized to a predetermined pressure, so check The oil in the second return passage surely flows into the inlet side passage through the valve.

In the third aspect of the invention, when the flow path of the pressure oil is switched to the line path by the control valve, the actuator is operated by the pressure oil which is supplied by being divided together with the other hydraulic system by the hydraulic pump, and the two members are operated. The relative posture state between them is actively controlled. Further, when the flow path of the pressure oil is switched to the return path to the reservoir tank by the control valve, if a relative posture change occurs between the two members, the oil flow between the two hydraulic chambers of the actuator is controlled by the control valve. Done through. Even if the pressure in the line passage on the oil inlet side decreases due to continuous posture change, the back pressure valve keeps the second return passage pressurized to a predetermined pressure. Through this, the oil in the second return passage surely flows into the inlet side line passage.

According to the fourth aspect of the invention, when the flow path of the pressure oil is switched to the line path by the control valve, the actuator is actuated by the pressure oil which is divided and supplied together with the other hydraulic system by the hydraulic pump, and the two members are operated. The relative posture state between them is actively controlled. Further, when the flow path of the pressure oil is switched to the return path to the reservoir tank by the control valve, if a relative posture change occurs between the two members, the oil flow between the two hydraulic chambers of the actuator is controlled by the control valve. Done through. Even if the pressure in the line passage on the oil inlet side decreases due to continuous posture change, the back pressure valve and accumulator keep the second return passage pressurized to a predetermined pressure, so check The oil in the second return passage surely flows into the inlet side passage through the valve.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the damping force control device of the present invention will be described below with reference to the drawings. The illustrated embodiment is applied to a suspension of a vehicle as a damping force control device and corresponds to claims 4 and 6. FIG. 1 shows a hydraulic circuit state of an actuator in a vehicle suspension applied as a damping force control device according to an embodiment of the present invention.

An actuator 31 is provided on the vehicle body side (not shown).
The main body 32 is attached, and the movable portion 34 that is movable with respect to the main body 32 via the piston rod 33 is attached to the wheel side (not shown). That is, the two members are the vehicle body and the wheels of the automobile. Pressure oil is supplied to the first hydraulic chamber 35 of the actuator 31 and the second hydraulic chamber 3
When the pressure oil is discharged from 6, the movable portion 34 moves upward in the figure via the piston rod 33, and conversely, the second hydraulic chamber 36
When the pressure oil is supplied to the first hydraulic chamber 35 and the pressure oil is discharged from the first hydraulic chamber 35, the movable portion 34 moves downward in the drawing via the piston rod 33. Also, the main body 3 of the actuator 31
A compression coil spring 37 is provided between the movable portion 34 and the movable portion 34, and the compression coil spring 37 urges the movable portion 34 downward in the figure to support a 1G load of the vehicle body (not shown).

On the other hand, a hydraulic pump 38 for power steering is connected to an engine (not shown), and the hydraulic pump 3
A part (about 0.3 MPa) of the pressure oil generated by the driving of No. 8 is sent to the actuator 31 via the priority valve 39. That is, the hydraulic pump 38
The pressure oil is shunted and supplied to the actuator 31 and a power steering device (not shown) as another hydraulic system. A switching valve 40 is provided between the priority valve 39 and the actuator 31, and a pressure oil flow path is provided in a return path 42 to the reservoir tank 41 and a line path 43 connected to the actuator 31 side by turning the switching valve 40 on and off. Are switched. That is, when the switching valve 40 is turned off (the illustrated state), the pressure oil from the priority valve 39 is sent to the return path 42 and returned to the reservoir tank 41. Further, when the switching valve 40 is turned on, the pressure oil from the priority valve 39 is supplied to the line passage 4
Sent to 3.

The line passage 43 is provided with an electromagnetic pressure control valve 44 as a control valve, and the line passage 43 is connected via the electromagnetic pressure control valve 44 to the first hydraulic chamber 3 of the actuator 31.
5 and the second hydraulic chamber 36. The electromagnetic pressure control valve 44 has a structure in which a thrust force proportional to the current is generated by the solenoid, and the spool stops at a position where the spool balances the output pressure. Therefore, it is possible to generate a pressure according to the command signal, to send pressure oil to the first hydraulic chamber 35 or the second hydraulic chamber 36 at an arbitrary pressure, or to send a pressure between the first hydraulic chamber 35 and the second hydraulic chamber 36. The pressure oil can be circulated by. That is,
The electromagnetic pressure control valve 44 controls the hydraulic pressure in the first hydraulic chamber 35 and the second hydraulic chamber 36 of the actuator 31.

The discharge port of the electromagnetic pressure control valve 44 is the flow path 4
5 is connected to the return path 42 by the electromagnetic pressure control valve 44
A second return path 46 is provided branching from each line path 43 on the downstream side. Each second return path 46 merges with the flow path 45, and the second return path 46 is in a state of being connected to the return path 42 via the flow path 45. Each of the second return passages 46 is provided with a check valve 47 that allows oil to flow only from the flow passage 45 side (only from the return passage 42 side), and the inside of the first hydraulic chamber 35 or the second hydraulic chamber 36. The oil from the side of the return passage 42 flows into the line passage 43 in accordance with the pressure difference when the pressure becomes relatively low.
In the drawings, reference numeral 20 is a return pipe from a power steering device (not shown), and 21 is an oil return pipe for the sliding portion of the actuator 1.

On the other hand, an accumulator 61 is provided in the passage 45, and the accumulator 61 accumulates the hydraulic pressure in the second return passage 46 and the passage 45 on the downstream side from the check valve 47. In other words, the return path 42 rather than the check valve 47.
The accumulator 6 is provided in the second return path 46 at the confluence portion with
1 is provided. In addition, a back pressure valve 62 is provided in the return passage 42, and the back pressure valve 62 allows the passage 4
The oil is allowed to flow from the flow path 45 side to the reservoir tank 41 side only when the oil pressure from the 5 side (second return path 46 side) becomes equal to or higher than a predetermined value. That is, when the switching valve 40 is turned off and the pressure oil is sent to the return passage 42 side, the return passage 42 and the accumulator 61 are pressurized by the pressure oil until the back pressure valve 62 is opened when the pressure becomes equal to or higher than a predetermined pressure. It is in the state of being Although the case where the accumulator 61 is provided has been described in the above embodiment, the accumulator 61 does not necessarily have to be provided (claims 1 and 3).

The operation of the above-mentioned suspension will be described. When a predetermined attitude control condition is satisfied while the vehicle is traveling, that is, when the vehicle travels straight, the value detected by the vertical G sensor exceeds a predetermined value, or the calculated lateral g calculated by the steering wheel angle and the vehicle speed is predetermined. When the value is exceeded and the control for suppressing rolling or pitching is performed, the switching valve 40 is turned on and the attitude control by the actuator 31 is executed. That is, the pressure oil from the hydraulic pump 38 is sent to the electromagnetic pressure control valve 44, and for example, the predetermined pressure oil flows into the first hydraulic chamber 35 and the pressure oil is discharged from the second hydraulic chamber 36, so that the movable portion 34 is moved. Is positively raised with respect to the main body 32, and the actuator 31 is operated in a state where vertical G and lateral g are not generated on the vehicle body.

During normal traveling, the switching valve 40 is turned off and the pressure oil from the hydraulic pump 38 is sent to the return path 42. Since the back passage valve 62 is provided in the return passage 42, the pressure oil sent to the return passage 42 is not sent to the reservoir tank 41 as it is, and the return passage 42 and the accumulator 61 are pressurized until the back pressure valve 62 is opened. . In this state, if there is input from the wheel side due to unevenness of the road surface,
The movable portion 34 of the actuator 31 moves up and down with respect to the main body 32, and the oil flows between the first hydraulic chamber 35 and the second hydraulic chamber 36 via the electromagnetic pressure control valve 44. At this time, the flow resistance of the oil discharged from the hydraulic chamber on the side compressed by the set pressure of the electromagnetic pressure control valve 44 is adjusted, and the input from the wheel side is attenuated by the actuator 31.

As described above, when the switching valve 40 is in the off state, the input from the wheel side is damped by the actuator 31 by the set pressure of the electromagnetic pressure control valve 44. In this case, continuous input from the wheel side due to unevenness of the road surface results in continuous reciprocating motion of the movable portion 34, and the oil discharged from one hydraulic chamber causes the electromagnetic pressure control valve 4 to move.
The flow through 4 into the other hydraulic chamber is repeated. When the continuous reciprocating movement of the movable portion 34 becomes faster, the pressure in the inflow-side line passage 33 temporarily decreases. Flows into the line passage 43 through the second return passage 46. Since the back pressure valve 62 is provided,
Since the flow passage 45 is pressurized and the pressure oil is accumulated in the accumulator 61, the inflow of the oil from the check valve 47 is surely performed even if the movable portion 34 reciprocates in a relatively rapid manner. Therefore, the line passage 43 on the inflow side does not become a negative pressure and bubbles are not generated in the pipe.

In the above-mentioned suspension, since the accumulator 61 and the back pressure valve 62 are provided, the inside of the flow path 45 is pressurized and the inside of the reservoir tank 41 is pressurized so that the inside of the pipe is constantly pressurized. Since it is possible to reliably carry out the inflow of oil from the check valve 47 and to prevent bubbles from being generated in the pipe, it is not necessary to seal the reservoir tank 41 and the pipe connection portion can be simply fixed. Therefore, the hydraulic path for power steering is not affected by pressurization for preventing bubble generation. For this reason,
It is not necessary to strengthen the pipes and connection parts in anticipation of pressure fluctuations due to temperature changes of the oil in the reservoir tank 41, and there is no need to perform any special pressurizing operation even when maintenance such as oil replenishment is performed. Further, since the accumulator 61 is provided, the negative pressure can be reliably supplied even when the rotation speed of the hydraulic pump 38 becomes low. This accumulator 61 does not need a large-scale device, because it only needs to store a negative pressure equivalent to the deformation of the pipe.

In the above embodiment, an example in which the suspension is provided with the actuator 31 operated by the power steering hydraulic pump 38 has been described, but an actuator operated by a dedicated hydraulic pump may be used. (Claims 1 and 2). Further, although the example in which the damping force control device is applied to a suspension for a vehicle has been described, the present invention is not limited to this and can be used for controlling the damping force of an industrial machine or the like ( Claims 1 to 4).

[0033]

According to the first aspect of the present invention, a back pressure valve is provided in the return path from the hydraulic pump to the reservoir tank, and the back pressure valve is provided from the second return path side only when the pressure oil from the second return path side becomes a predetermined value or more. Since the circulation of oil is allowed on the return road side,
The inside of the second return path is pressurized without the inside of the pipe being constantly pressurized, and the inside of the reservoir tank is pressurized to keep the inside of the pipe from being pressurized all the time. It is possible to reliably carry out the inflow and eliminate the generation of bubbles in the pipe. As a result, it is possible to prevent the pressure drop in the line path without providing a large-scale pressurizing means in the reservoir tank or rigidly fixing the pipes, and maintain good maintainability and prevent the generation of bubbles in the pipes. It becomes possible to do.

According to the second aspect of the present invention, the back pressure valve is provided on the return path from the hydraulic pump to the reservoir tank, and the accumulator is provided on the second return path, so that the pressure oil from the second return path side becomes a predetermined value or more. In this case, the oil is allowed to flow from the second return path side to the return path side only, so that the inside of the second return path is pressurized and accumulated without constantly pressurizing the inside of the pipe, and the reservoir It is possible to reliably inject oil from the check valve without pressurizing the inside of the tank to constantly pressurize the inside of the pipe, and to eliminate the generation of bubbles in the pipe. As a result, it is possible to prevent pressure drop in the line passage regardless of the rotation state of the hydraulic pump without providing a large-scale pressurizing means in the reservoir tank or rigidly fixing the pipes, and maintainability is good. It is possible to prevent the generation of air bubbles in the pipe by keeping the above.

According to the third invention, a back pressure valve is provided in the return path from the hydraulic pump sharing the other hydraulic system to the reservoir tank, and only when the pressure oil from the second return path side exceeds a predetermined value. Since the oil is allowed to flow from the second return path side to the return path side, the inside of the second return path is pressurized without constantly pressurizing the inside of the pipe, and the inside of the reservoir tank is pressurized. It is possible to reliably carry out the inflow of oil from the check valve without constantly pressurizing the inside of the pipe to eliminate the generation of bubbles in the pipe. As a result, it becomes possible to prevent the pressure drop in the line passage without affecting other hydraulic systems that are commonly used by providing a large-scale pressurizing means in the reservoir tank or by firmly fixing the pipes. It becomes possible to prevent the generation of air bubbles in the pipe by keeping it in good condition.

According to the fourth invention, a back pressure valve is provided in the return path from the hydraulic pump sharing the other hydraulic system to the reservoir tank, and an accumulator is provided in the second return path.
Since the oil is allowed to flow from the second return path side to the return path side only when the pressure oil from the second return path side becomes equal to or more than a predetermined value, it is possible to prevent the second pipe from being constantly pressurized in the pipe.
The inside of the return path becomes pressurized and accumulated, and the oil in the check valve is reliably flowed in without constantly pressurizing the inside of the reservoir tank to keep the inside of the piping pressurized. Occurrence can be eliminated. As a result, a large-scale pressurizing means is provided in the reservoir tank or strong piping is fixed so that other shared hydraulic systems are not affected, and pressure drop in the line passage is prevented regardless of the rotating state of the hydraulic pump. Therefore, it is possible to prevent air bubbles from being generated in the pipe while maintaining good maintainability.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit configuration diagram of an actuator in a vehicle suspension applied as a damping force control device according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit configuration diagram of an actuator in a conventional suspension.

[Explanation of symbols]

 31 actuator 32 main body 33 piston rod 34 movable part 35 first hydraulic chamber 36 second hydraulic chamber 37 compression coil spring 38 hydraulic pump 39 priority valve 40 switching valve 41 reservoir tank 42 return path 43 line path 44 electromagnetic pressure control valve 45 flow path 46 Second Return Path 47 Check Valve 50 Piping 51 Piping 61 Accumulator 62 Back Pressure Valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Morita 5-3-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (6)

[Claims] 1. A double-acting actuator interposed between two members to absorb a relative change in posture between the two members, a hydraulic pump for supplying pressure oil to the actuator, the actuator, and the actuator. A switching valve provided between the hydraulic pump and a return passage to the reservoir tank and a line passage connected to the actuator side, and a switching valve, and an oil provided in the line passage in the two hydraulic chambers of the actuator. A control valve for controlling the pressure, a second return path that branches from the line path on the downstream side of the control valve and joins the return path, and a second return path provided in the middle of the second return path from the return path side. A check valve that allows the passage of oil only, and is provided between the return passage and the reservoir tank, and only when the oil pressure from the return passage side exceeds a predetermined value, the front side from the return passage side A damping force control device, comprising: a back pressure valve that allows oil to flow to the reservoir tank side. 2. A double-acting actuator interposed between two members to absorb a relative posture change between the two members, a hydraulic pump for supplying pressure oil to the actuator, the actuator and the actuator. A switching valve provided between the hydraulic pump and a return passage to the reservoir tank and a line passage connected to the actuator side, and a switching valve, and an oil provided in the line passage in the two hydraulic chambers of the actuator. A control valve for controlling the pressure, a second return path that branches from the line path on the downstream side of the control valve and joins the return path, and a second return path provided in the middle of the second return path from the return path side. A check valve that allows the flow of oil only, and an accumulator that is provided in the second return path on the side of the return path that is closer to the return path than the check valve, and that accumulates the hydraulic pressure in the second return path. A back pressure valve which is provided between the return path and the reservoir tank and allows the oil to flow from the return path side to the reservoir tank side only when the oil pressure from the return path side exceeds a predetermined value. A damping force control device comprising: 3. A double-acting actuator which is interposed between two members and absorbs a relative attitude change between the two members, and pressure oil is shunted and supplied to the actuator and other hydraulic systems. A hydraulic pump, a switching valve provided between the actuator and the hydraulic pump, for switching the flow path of the pressure oil to a return path to the reservoir tank, and a line path connected to the actuator side; A control valve that controls the hydraulic pressure in the two hydraulic chambers of the actuator, a second return path that branches from the line path on the downstream side of the control valve and joins with the return path, and the middle of the second return path. A check valve that is provided in a section that allows oil to flow only from the return path side, and a case where the oil pressure from the return path side that is provided between the return path and the reservoir tank exceeds a predetermined value. And a back pressure valve that allows the oil to flow from the return path side to the reservoir tank side only when the damping force control apparatus is in a closed state. 4. A double-acting actuator which is interposed between two members and absorbs a relative attitude change between the two members, and pressure oil is shunted and supplied to the actuator and other hydraulic systems. A hydraulic pump, a switching valve provided between the actuator and the hydraulic pump, for switching the flow path of the pressure oil to a return path to the reservoir tank, and a line path connected to the actuator side; A control valve that controls the hydraulic pressure in the two hydraulic chambers of the actuator, a second return path that branches from the line path on the downstream side of the control valve and joins with the return path, and the middle of the second return path. A check valve that is provided in a portion that allows the oil to flow only from the return path side, and a second return path that is provided in the second return path on the side of the merging portion with the return path that is closer than the check valve. Hydraulic pressure An oil accumulator for accumulating and provided between the return path and the reservoir tank to allow oil to flow from the return path side to the reservoir tank side only when the oil pressure from the return path side becomes a predetermined value or more. And a back pressure valve for controlling the damping force control device. 5. The damping force according to claim 1 or 3, wherein the two members are a vehicle body side and a wheel side of an automobile, and the actuator is a damper of a suspension device for supporting the vehicle body. Control device. 6. The two members are a vehicle body side and a wheel side in an automobile, the actuator is a damper of a suspension device for supporting the vehicle body, and the other hydraulic system is a power steering assisting steering force of the steering. The damping force control device according to claim 2 or 4, which is a hydraulic system of the device.