JP2017196919A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device that enables regeneration of energy.SOLUTION: A suspension device S1 is configured to comprise: a damper D; a pump 4; a reservoir R to be connected to a suction side of the pump 4; a supply path 5 to be connected to a discharge side of the pump 4; an exhaust path 6 to be connected to the reservoir R; an extension-side passage 7 to be connected to an extension-side chamber R1 of the damper D; a pressure-side passage 8 to be connected to a pressure-side chamber R2 of the damper D; a direction switching valve 9; an electromagnetic valve V1 provided between the supply path 5 and the exhaust path 6; a hydraulic motor Hm to be provided in the exhaust path 6; and a power generator G to be driven by the hydraulic motor Hm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a suspension device.

  As this type of suspension device, for example, there is one that functions as an active suspension interposed between a vehicle body and an axle of a vehicle. Specifically, the suspension body including a cylinder and a piston that is movably inserted into the cylinder and defines a pressure chamber in the cylinder, a hydraulic pump, and an oil that connects the pressure chamber in the suspension body and the hydraulic pump. A path, an electromagnetic on-off valve provided in the middle of the oil path for opening and closing the oil path, and an electromagnetic pressure control valve for controlling the pressure in the pressure chamber (see, for example, Patent Document 1).

JP-A-9-240241

  In the suspension device functioning as the active suspension described above, vibration energy cannot be recovered as electric energy only by consuming energy.

  In view of this, the present invention was devised to improve the above-mentioned problem, and its object is to provide a suspension device capable of energy regeneration.

  In order to solve the above-described object, the suspension device in the problem solving means of the present invention includes a damper, a pump, a reservoir connected to the suction side of the pump, a supply path connected to the discharge side of the pump, and a reservoir A discharge path connected to the extension side chamber of the damper, an extension side passage connected to the extension side chamber of the damper, a pressure side passage connected to the pressure side chamber of the damper, a direction switching valve, and an electromagnetic wave provided between the supply path and the discharge path It comprises a valve, a hydraulic motor provided in the discharge path, and a generator driven by the hydraulic motor. If comprised in this way, a hydraulic motor can be driven using the flow of a liquid, a generator can be driven, and electrical energy can be obtained from vibration energy.

  In the suspension device according to the second aspect, the electromagnetic valve is provided in the control passage connecting the supply passage and the discharge passage, and the hydraulic motor is provided in the control passage downstream of the electromagnetic valve. If comprised in this way, a hydraulic motor can be driven using the flow of the liquid which passes an electromagnetic valve, and a dynamo can be driven, and regeneration which acquires electric energy from vibration energy is attained.

  According to a third aspect of the present invention, the hydraulic motor is provided in the discharge path, the supply-side pressure sensor for detecting the pressure in the supply path, the discharge-side pressure sensor for detecting the pressure in the discharge path, and the discharge path. A bypass passage that bypasses the hydraulic motor, and a bypass passage-side check valve that is provided in the bypass passage and allows only the flow of liquid from the reservoir side toward the direction switching valve side. If the suspension device is configured in this way, the hydraulic motor is driven and the generator generates electricity whenever the liquid returns to the reservoir, so that there are many generation opportunities and the vibration energy is efficiently regenerated and electric energy can be obtained. .

  Furthermore, in the suspension device according to claim 4, an extension side damping element that provides resistance to the flow from the extension side chamber toward the direction switching valve and that allows the opposite direction flow is provided in the extension side passage, and the compression side. A pressure-side damping element that provides resistance to the flow from the pressure-side chamber toward the direction switching valve and allows the flow in the opposite direction; a suction passage that connects the supply passage and the discharge passage; A suction check valve that is provided in the middle of the passage and allows only the flow of liquid from the discharge path to the supply path, and is provided in the middle of the supply path between the solenoid valve and the pump, from the pump side to the solenoid valve side. And a supply-side check valve that allows only the flow to the front. According to the suspension device configured in this manner, not only the damper is actively expanded and contracted to function as an active suspension, but also in a scene where a thrust as a semi-active suspension is expected to be driven, it is not necessary to drive the pump. Disappear. Therefore, this suspension device needs to be driven only when the pump needs to be driven, so that the energy consumption is extremely reduced, and can automatically function as a semi-active suspension.

  In the suspension device according to the fifth aspect, the extension side damping element provides resistance to the flow from the extension side chamber to the direction switching valve, and the extension side damping valve is arranged in parallel with the extension side damping valve to move from the direction switching valve to the extension side chamber. A pressure-side damping valve having a pressure-side damping element that provides resistance to a flow from the pressure-side chamber toward the direction switching valve, and a pressure-side damping valve in parallel with the pressure-side damping valve. And a pressure check valve that allows only flow toward the chamber. In this way, when supplying the liquid from the pump to the extension side chamber or the pressure side chamber, the liquid can be supplied to the extension side chamber or the pressure side chamber through the extension side check valve or the pressure side check valve with almost no resistance. Therefore, in this suspension device, the load on the pump can be reduced when the expansion / contraction direction of the damper matches the direction of the generated thrust. Further, when the liquid is discharged from the expansion side chamber or the pressure side chamber, resistance is given to the flow of the liquid passing through the expansion side damping valve or the pressure side damping valve, so that the pressure in the expansion side chamber or the pressure side chamber is controlled by the control pressure of the solenoid valve. A large thrust can be obtained as described above. Therefore, even if the thrust of the solenoid valve is reduced, a large thrust can be generated in the suspension device, so that the solenoid valve can be reduced in size and the cost can be reduced.

  According to the suspension device of the present invention, energy regeneration is possible.

It is the figure which showed the suspension apparatus in 1st embodiment. It is the figure which interposed the suspension apparatus between the vehicle body and the wheel of the vehicle. It is a figure showing the characteristic of thrust at the time of making a suspension device function as an active suspension. It is a figure showing the characteristic of thrust at the time of making a suspension device function as a semi-active suspension. It is the figure which showed the characteristic of the thrust at the time of failure of a suspension apparatus. It is the figure which showed the suspension apparatus in 2nd embodiment.

  Hereinafter, the present invention will be described based on the first and second embodiments shown in the drawings. In the suspension device S1 of the first embodiment and the suspension device S2 of the second embodiment, the members and parts denoted by the same reference numerals have the same configuration. Therefore, in order to avoid duplication of description, it will be described in detail in the description of the suspension device S1 of the first embodiment, and detailed description will be omitted in the description of the suspension device S2 of the second embodiment.

<First embodiment>
As shown in FIG. 1, the suspension device S <b> 1 in the first embodiment includes a damper D, a pump 4, a reservoir R connected to the suction side of the pump 4, and a supply path connected to the discharge side of the pump 4. 5, a discharge path 6 connected to the reservoir R, an extension side passage 7 connected to the extension side chamber R1 of the damper D, a pressure side passage 8 connected to the pressure side chamber R2 of the damper D, and a direction switching valve 9 The electromagnetic valve V1 provided between the supply path 5 and the discharge path 6, a hydraulic motor Hm provided in the discharge path 6, and a generator G driven by the hydraulic motor Hm. Yes.

  In this suspension device S1, the damper D is disposed in the cylinder 1, the piston 2, which is movably inserted into the cylinder 1, and divides the cylinder 1 into the expansion side chamber R1 and the pressure side chamber R2, and the cylinder 1. A rod 3 that is movably inserted and connected to the piston 2 is provided. This rod 3 is inserted only into the extension side chamber R1, and the damper D is a so-called single rod type damper. The damper D may be a so-called double rod type damper in which the rod 3 is inserted into the extension side chamber R1 and the compression side chamber R2. Further, in this example, the reservoir R is provided independently of the damper D, but an outer cylinder disposed on the outer peripheral side of the cylinder 1 in the damper D is provided, and an annular shape between the cylinder 1 and the outer cylinder is provided. The reservoir R may be formed with a gap.

  As shown in FIG. 2, the damper D of the suspension device S1 connects the cylinder 1 to one of the sprung member Bo and the unsprung member W of the vehicle, and connects the rod 3 to the sprung member Bo and the unsprung member W. It connects with the other among them, and is interposed between the sprung member Bo and the unsprung member W.

  The extension side chamber R1 and the pressure side chamber R2 are filled with, for example, hydraulic oil as liquid, and the reservoir R is also filled with liquid and gas. As the liquid filled in the extension side chamber R1, the pressure side chamber R2, and the reservoir R, for example, a liquid such as water or an aqueous solution can be used in addition to the hydraulic oil. In the present invention, the chamber compressed during the expansion stroke is referred to as an expansion side chamber R1, and the chamber compressed during the contraction stroke is referred to as a compression side chamber R2.

  The pump 4 is set to a one-way discharge type that sucks liquid from the suction side and discharges liquid from the discharge side, and is driven by a motor 13. Various types of motors such as brushless motors, induction motors, synchronous motors and the like can be adopted as the motor 13 regardless of whether they are direct current or alternating current.

  The suction side of the pump 4 is connected to the reservoir R by a pump passage 14, and the discharge side is connected to the supply path 5. Therefore, when driven by the motor 13, the pump 4 sucks liquid from the reservoir R and discharges the liquid to the supply path 5. The supply path 5 has one end connected to the pump 4 as described above and the other end connected to the direction switching valve 9.

  The discharge path 6 has one end connected to the reservoir R and the other end connected to the direction switching valve 9. The discharge path 6 returns the excess liquid out of the liquid discharged from the damper D or the liquid discharged from the pump 4 to the reservoir R, and supplies the liquid from the reservoir R to the damper D when the liquid is insufficient in the damper D. The function to perform is also demonstrated.

  The extension side passage 7 has one end connected to the extension side chamber R <b> 1 of the damper D and the other end connected to the direction switching valve 9. In this example, an extension side damping element VE that provides resistance to the flow of liquid from the extension side chamber R1 to the direction switching valve 9 and allows the flow of liquid in the opposite direction is provided in the middle of the extension side passage 7. Yes.

  The extension side damping element VE includes an extension side damping valve 15 that provides resistance to the flow of liquid from the extension side chamber R1 to the direction switching valve 9, and the extension side damping valve 15 in parallel with the extension side damping valve 15 from the direction switching valve 9 to the extension side chamber R1. And an extension-side check valve 16 that allows only the flow of liquid toward it. Therefore, when the liquid flows from the expansion side chamber R1 toward the direction switching valve 9, the expansion side check valve 16 is closed, so that the liquid flows only through the expansion side damping valve 15 toward the direction switching valve 9 side. On the contrary, when the liquid flows from the direction switching valve 9 toward the extension side chamber R1, the extension side check valve 16 is opened. Since the extension side check valve 16 has a smaller resistance to the liquid flow than the extension side damping valve 15, the liquid preferentially passes through the extension side check valve 16 and flows toward the extension side chamber R1. The expansion side damping valve 15 may be a throttle valve that allows bidirectional flow, or may be a damping valve such as a leaf valve or a poppet valve that allows only the flow of liquid from the expansion side chamber R1 toward the direction switching valve 9. Also good.

  The pressure side passage 8 has one end connected to the pressure side chamber R <b> 2 of the damper D and the other end connected to the direction switching valve 9. In this example, a pressure-side damping element VC is provided in the middle of the pressure-side passage 8 to provide resistance to the liquid flow from the pressure-side chamber R2 toward the direction switching valve 9 and to allow the liquid flow in the opposite direction.

  The pressure-side damping element VC includes a pressure-side damping valve 17 that provides resistance to the flow of liquid from the pressure-side chamber R2 toward the direction switching valve 9, and a liquid that is parallel to the pressure-side damping valve 17 and travels from the direction switching valve 9 toward the pressure-side chamber R2. And a pressure side check valve 18 that allows only the flow of gas. Therefore, when the liquid flows from the pressure side chamber R2 toward the direction switching valve 9, the pressure side check valve 18 is closed, so that the liquid flows only through the pressure side damping valve 17 toward the direction switching valve 9 side. On the contrary, when the liquid flows from the direction switching valve 9 toward the pressure side chamber R2, the pressure side check valve 18 is opened. Since the pressure side check valve 18 has a smaller resistance to the liquid flow than the pressure side damping valve 17, the liquid preferentially passes through the pressure side check valve 18 and flows toward the pressure side chamber R2. The pressure side damping valve 17 may be a throttle valve that allows bidirectional flow, or may be a damping valve such as a leaf valve or a poppet valve that only allows flow from the pressure side chamber R2 toward the direction switching valve 9.

  The direction switching valve 9 is a 4-port 2-position electromagnetic switching valve. Specifically, a valve body 9a, a spring 9d that biases the valve body 9a, and a solenoid 9e that applies a thrust to the valve body 9a against the spring 9d are provided. The valve body 9a communicates the port A and the port P and communicates the port B and the port T with the expansion side supply position 9b, and communicates the port A and the port T with the pressure side supply communicating the port B and the port P. And a position 9c. When no power is supplied to the solenoid 9e, the valve body 9a is urged by the spring 9d to take the extended supply position 9b. When the solenoid 9e is energized, the valve body 9a is pushed by the thrust from the solenoid 9e. The pressure side supply position 9c is adopted.

  The port P of the direction switching valve 9 is connected to the discharge side of the pump 4 via the supply path 5, the port T is connected to the reservoir R via the discharge path 6, and the port A passes through the expansion side path 7. The port B is connected to the pressure side chamber R2 via the pressure side passage 8.

  Therefore, when the direction switching valve 9 adopts the expansion side supply position 9b, the supply path 5 is communicated with the expansion side chamber R1 through the expansion side passage 7, and the discharge path 6 is communicated with the pressure side chamber R2 through the pressure side passage 8. When the pump 4 is driven in this state, the liquid is supplied to the expansion side chamber R1 and the liquid is discharged from the compression side chamber R2 to the reservoir R. Therefore, when no external force acts on the damper D, the damper D contracts. On the other hand, when the direction switching valve 9 adopts the pressure side supply position 9c, the supply path 5 is communicated with the pressure side chamber R2 through the pressure side path 8, and the discharge path 6 is communicated with the expansion side chamber R1 through the expansion side path 7. When the pump 4 is driven in this state, the liquid is supplied to the pressure side chamber R2 and discharged from the extension side chamber R1 to the reservoir R. Therefore, when no external force acts on the damper D, the damper D extends. As described above, the direction switching valve 9 selects and communicates the supply path 5 with one of the expansion side path 7 and the pressure side path 8, and connects the discharge path 6 with the other of the expansion side path 7 and the pressure side path 8.

  In addition, although liquid is discharged from the pump 4 to the supply path 5, in this example, an electromagnetic valve V1 is provided in order to control the magnitude of thrust generated by the damper D of the suspension device S1. Specifically, the electromagnetic valve V1 is provided in a control passage 19 that connects the supply passage 5 and the discharge passage 6, and in this example, as will be described later, the supply passage of the electromagnetic valve V1 by adjusting the valve opening degree. The difference (pressure difference) between the pressure 5 and the pressure in the discharge path 6 is controlled.

  In this example, the electromagnetic valve V <b> 1 is an electromagnetic throttle valve, and is provided in the middle of the control passage 19. Specifically, the solenoid valve V1 has a valve body 20a that opens and closes the control passage 19, a spring 20d that biases the valve body 20a in the direction of taking the open position 20b, and a thrust that opposes the spring 20d. The solenoid 20e which can be provided is provided. The valve body 20 a has an open position 20 b that opens the control passage 19 and a closed position 20 c that blocks the control passage 19. The solenoid 20e is composed of a spring and a coil (not shown). When energized, the solenoid 20e generates a thrust force that opposes the spring that urges the valve body 20a, and drives the valve body 20a to the closed position 20c side to drive the electromagnetic valve V1. Reduce the valve opening at. Therefore, when the energization amount to the solenoid 20e is adjusted, the valve opening degree of the electromagnetic valve V1 can be adjusted, and the differential pressure can be controlled to a control pressure corresponding to the valve opening degree of the electromagnetic valve V1. As described above, the electromagnetic valve V1 can adjust the differential pressure in accordance with the supply current. However, the specific configuration of the electromagnetic valve V1 is merely an example, and is not limited thereto. It may be a pressure control valve.

  In this electromagnetic valve V1, a valve opening proportional to the amount of current supplied to the solenoid 20e can be obtained. The larger the amount of current, the smaller the valve opening. The resistance given to the flow of liquid increases. On the other hand, when no current is supplied to the electromagnetic valve V1, the valve opening becomes maximum, and the resistance that the electromagnetic valve V1 gives to the flow of liquid becomes minimum.

  In order to control the differential pressure between the upstream supply path 5 and the downstream discharge path 6 with the electromagnetic valve V1, in this example, the pressure on the supply side pressure sensor 31 that detects the pressure on the supply path 5 and the pressure on the discharge path 6 are used. A discharge-side pressure sensor 32 that detects this is used. In addition, the suspension device S1 of this example includes a controller C and a driver device Dr, as shown in FIG. 1, and controls the thrust exerted by the damper D. Specifically, the pressures of the supply passage 5 and the discharge passage 6 are detected by the pressure sensors 31 and 32, and the controller C obtains a differential pressure that is a difference between the detected pressures, and the target differential pressure obtained by the controller C. The target current to be supplied to the solenoid 20e is obtained from the detected deviation of the actual differential pressure. In the controller C, the target differential pressure may be obtained from the target thrust generated by the damper D.

  In addition to the pressure detected by the pressure sensors 31 and 32 described above, the controller C is input with vehicle vibration information capable of grasping the vehicle vibration state necessary for the control law suitable for vehicle vibration suppression. The vehicle vibration information is, for example, information such as the vertical acceleration and speed of the sprung member Bo and the unsprung member W, information such as the expansion and contraction speed and expansion acceleration of the damper D, and the like. As a control law used for thrust control in the suspension device S1, a control law suitable for the vehicle may be selected, and for example, a control law excellent in vehicle vibration suppression such as skyhook control may be employed. The controller C obtains the target thrust of the damper D from the vibration information in accordance with the control law, and the amount of current applied to the electromagnetic valve V1 and the positions 9b and 9c of the direction switching valve 9 to generate the thrust on the damper D according to the target thrust. And the amount of current applied to the motor 13 is determined.

  The driver device Dr includes, for example, a drive circuit for PWM driving the solenoid 20e and the solenoid 9e in the electromagnetic valve V1 and the direction switching valve 9, and a drive circuit for PWM driving the motor 13. When the driver device Dr receives a command from the controller C, the driver device Dr supplies current to the solenoids 9e and 20e and the motor 13 as determined by the controller C. Note that each drive circuit in the driver device Dr may be a drive circuit other than the drive circuit that performs PWM drive. When the target thrust generated in the damper D is the extension direction of the damper D, the controller C selects the pressure side supply position 9c for the direction switching valve 9. Further, when the target thrust generated in the damper D is the contraction direction of the damper D, the controller C selects the extension side supply position 9b for the direction switching valve 9. Further, the driver device Dr supplies or stops the current to the solenoid 9e in order to switch the direction switching valve 9 to the position selected as described above. Specifically, in this example, when the damper D is contracted, the liquid is supplied to the extension side chamber R1 and the liquid is discharged from the pressure side chamber R2 to the reservoir R. For this purpose, the directional control valve 9 is not supplied with current but is de-energized so that the directional control valve 9 takes the extended supply position 9b. On the other hand, when the damper D is operated to extend, the liquid is supplied to the compression side chamber R2 and the liquid is discharged from the extension side chamber R1 to the reservoir R. For this purpose, current is supplied to the solenoid 9e in the direction switching valve 9 so that the direction switching valve 9 takes the pressure side supply position 9c. In this case, the controller C and the driver device Dr are described as separate units, but the suspension device S1 may be controlled by a single control device having the functions of the controller C and the driver device Dr. The information input to the controller C may be information suitable for the control law adopted by the controller C. Although not shown, the information may be detected by a sensor or the like and input to the controller C.

  When the target current obtained by the controller C is input in this way, the driver device Dr supplies current to the solenoid 20e according to the target current, and the valve opening degree of the electromagnetic valve V1 is controlled. Then, the differential pressure between the supply path 5 and the discharge path 6 is controlled according to the target differential pressure, and the thrust of the damper D is also controlled as intended. In controlling the electromagnetic valve V1, the pressure sensors 31 and 32 detect the pressure in the supply path 5 and the discharge path 6, so that it is possible to monitor whether the suspension device S1 is functioning normally. In this example, as the electromagnetic valve V1, various valves such as an electromagnetic pressure control valve can be used as the electromagnetic valve V1 as long as the differential pressure between the supply path 5 and the discharge path 6 can be adjusted according to the supply current.

  Further, a suction passage 10 that connects the supply passage 5 and the discharge passage 6 is provided in parallel to the control passage 19. A suction check valve 11 that allows only the flow of liquid from the discharge path 6 to the supply path 5 is provided in the middle of the suction path 10, and the suction path 10 has a liquid flow from the discharge path 6 to the supply path 5. It is set as a one-way passage that allows only flow.

  A supply side check valve 12 is provided in the middle of the supply path 5 and between the electromagnetic valve V 1 and the pump 4. More specifically, the supply side check valve 12 is provided in the middle of the supply path 5 and closer to the pump 4 than the connection point of the control passage 19 and the suction passage 10, and from the pump 4 side to the electromagnetic valve V1 side. Only allow the flow of liquid to go, and block the opposite flow. Therefore, even if the pressure on the direction switching valve 9 side becomes higher than the discharge pressure of the pump 4, the supply side check valve 12 is closed, so that the back flow of liquid to the pump 4 side is prevented.

  The hydraulic motor Hm is provided in the middle of the discharge passage 6 and between the connection point of the control passage 19 and the suction passage 10 and the connection point of the pump passage 14. The hydraulic motor Hm is driven to rotate by the flow of liquid from the direction switching valve 9 side toward the reservoir R side. The output shaft of the hydraulic motor Hm is connected to the input shaft of the generator G, and when the hydraulic motor Hm is driven to rotate, the generator G is driven to generate power.

  In this example, the discharge passage 6 is provided with a bypass passage Bi that bypasses the upstream and downstream of the hydraulic motor Hm. Specifically, one end of the bypass passage Bi is in the middle of the discharge passage 6, and the other end is a connection point of the pump passage 14 between the connection point of the control passage 19 and the suction passage 10 and the hydraulic motor Hm. Between the hydraulic motor Hm and the hydraulic motor Hm. Further, the bypass passage Bi is provided with a bypass passage-side check valve 21 that allows only the flow of liquid from the reservoir R side to the direction switching valve 9 side.

  Therefore, in this example, when the liquid flows through the discharge path 6 from the direction switching valve 9 side to the reservoir R side, the hydraulic motor Hm is rotationally driven and the generator G generates power. On the other hand, when the liquid goes from the reservoir R side to the direction switching valve 9 side through the discharge path 6, the bypass passage side check valve 21 opens to bypass the hydraulic motor Hm and pass through the bypass passage Bi.

  The suspension device S1 is configured as described above, and the operation thereof will be described. First, the operation at the normal time when the motor 13, the pump 4, the direction switching valve 9 and the electromagnetic valve V1 can be normally operated will be described.

  Basically, the pump 4 is driven by the motor 13, and one of the expansion side chamber R1 and the pressure side chamber R2 is connected to the supply path 5 by the direction switching valve 9 and is connected to the pump 4 to supply the liquid, and the discharge path When the other chamber is communicated with the reservoir R through 6, the damper D expands or contracts. In this case, the damper D can be positively extended or contracted to cause the damper D to function as an actuator. When the thrust generated in the damper D is in the extension direction of the damper D, the direction switching valve 9 is set to the pressure side supply position 9c, the pressure side chamber R2 is connected to the supply path 5, and the extension side chamber R1 is connected to the reservoir R. On the other hand, when the thrust generated in the damper D is in the contraction direction of the damper D, the direction switching valve 9 is set to the expansion side supply position 9b, the expansion side chamber R1 is connected to the supply path 5, and the pressure side chamber R2 is connected to the reservoir R. Connecting. When the differential pressure between the supply passage 5 and the discharge passage 6 is adjusted by the electromagnetic valve V1, the differential pressure between the expansion side chamber R1 and the compression side chamber R2 in the damper D is controlled, and the thrust in the extension direction or contraction direction exerted by the damper D is controlled. Can be controlled.

  The controller C obtains the target thrust of the damper D from the vibration information in accordance with the control law, and the amount of current applied to the electromagnetic valve V1 and the positions 9b and 9c of the direction switching valve 9 to generate the thrust on the damper D according to the target thrust. And the amount of current applied to the motor 13 is determined.

Specifically, when the shrinkage force of the damper D is positive, the target force and F, the cross-sectional area of the piston 2 and A _P, the cross-sectional area of the rod 3 and A _R, the pressure of the expansion side chamber R1 and P _1, if the pressure in the compression side chamber R2 and _{P 2,} the target differential pressure _P 1 -P ₂ is the pressure of _{P 2, P 1 -P 2 =} (F + a R · P 2) / (a P -A _R ).

The controller C supplies the current to the motor 13 via the driver device Dr to control the pump 4 and controls the pump 4 to keep a predetermined rotational speed even if the discharge pressure of the pump 4 changes. On top of that, the controller C, the pressure in the supply path 5 detected by the supply-side pressure sensor 31 and P _H, the pressure P _L of the discharge channel 6 for detecting the discharge-side pressure sensor 32, the actual differential pressure P _H - P _L controls the electromagnetic valve V1 to be equal to the target difference pressure _P 1 -P _2. Specifically, the controller C makes the deviation between the target differential pressure P ₁ -P ₂ and the actual differential pressure P _H -P _L obtained from the target thrust F and the pressure P ₂ of the compression side chamber R2 become zero. The amount of current supplied to the solenoid valve V1 is adjusted. The pressure P ₂ of the compression side chamber R2 can be grasped from one of the pressure which is connected to the compression side chamber R2 via the directional control valve 9 of the discharge passage 6 and the supply passage 5.

When the target thrust F is a force in the direction of pushing down the piston 2 with respect to the cylinder 1, the controller C does not energize the direction switching valve 9, but communicates the supply path 5 with the extension side chamber R1, and discharges the path 6 Is communicated with the compression side chamber R2. Then, the controller C is as described above, while controlling the pump 4, the actual differential pressure P _H -P _L adjusts the amount of current of the electromagnetic valve V1 such that the target difference pressure P ₁ -P _2. As a result, the damper D exerts a thrust in a direction in which the piston 2 is pushed down against the cylinder 1 in accordance with the target thrust F.

On the other hand, when the target thrust F is a force in the direction of pushing up the piston 2 with respect to the cylinder 1, the controller C energizes the direction switching valve 9, communicates the supply path 5 with the compression side chamber R2, and discharges the discharge path. 6 communicates with the extension chamber R1. Then, the controller C is as described above, while controlling the pump 4, the actual differential pressure P _H -P _L adjusts the amount of current of the electromagnetic valve V1 such that the target difference pressure P ₁ -P _2. Thereby, the damper D exhibits the thrust of the direction which pushes up the piston 2 with respect to the cylinder 1 according to the target thrust F.

  The operation in the case where the damper D is actively expanded and contracted has been described above. However, while the vehicle is traveling, the damper D expands and contracts due to disturbance due to the unevenness of the road surface. The operation based on the points to be described will be described.

  First, the operation in a state where the pump 4 is driven and liquid is discharged to the supply path 5 will be described. When the damper D expands and contracts due to a disturbance, four cases can be considered if the damper D is divided into the direction in which thrust is generated and the expansion and contraction direction of the damper D.

  First, a case where the damper D exerts a thrust force that pushes the piston 2 downward and the damper D is extended by an external force will be described. The direction of thrust generated in the damper D is a direction in which the piston 2 is pushed down, and it is necessary to supply liquid to the extension side chamber R1. Therefore, the controller C switches the direction switching valve 9 so as to adopt the expansion side supply position 9 b, connects the expansion side chamber R 1 to the supply path 5, and connects the pressure side chamber R 2 to the reservoir R through the discharge path 6.

  When the damper D is extended, the volume of the extension side chamber R1 is reduced. Therefore, the reduced amount of liquid is discharged from the extension side chamber R1 through the extension side damping valve 15, and further the electromagnetic valve V1 via the supply path 5. Flows to the reservoir R. Although the liquid discharged from the expansion side chamber R1 flows into the pressure side chamber R2 whose volume increases through the discharge path 6, the liquid corresponding to the volume retreated from the cylinder 1 of the rod 3 is insufficient in the pressure side chamber R2. The deficiency is replenished via the discharge path 6 by the liquid discharged from the pump 4. Of the flow rate of the liquid discharged from the pump 4, the surplus that could not be absorbed by the pressure side chamber R2 is returned to the reservoir R via the discharge path 6, but at that time, the liquid is supplied to the hydraulic motor Hm. Since it passes, the generator G is driven to generate electricity. Since the supply-side check valve 12 is provided, the liquid does not flow back to the pump 4 side even when the pressure in the supply path 5 is dynamically higher than the discharge pressure of the pump 4.

  When the extension speed of the damper D is fast and the discharge flow rate of the pump 4 cannot supply the liquid flow rate that is insufficient in the cylinder 1, the liquid is replenished from the reservoir R into the cylinder 1 via the discharge path 6. In this case, since the liquid is only supplied from the reservoir R to the damper D through the discharge path 6, the hydraulic motor Hm is not driven and power generation by the generator G is not performed.

  The differential pressure, which is the difference between the pressure in the supply path 5 and the pressure in the discharge path 6, is controlled by the electromagnetic valve V1, and the pressure in the expansion side chamber R1 is such that the liquid discharged from the expansion side chamber R1 passes through the expansion side damping valve 15. It becomes higher than the pressure of the supply path 5 by the amount of pressure loss that occurs. Therefore, in this case, even if the solenoid valve V1 controls the actual differential pressure according to the target differential pressure, the differential pressure between the expansion side chamber R1 and the compression side chamber R2 is equal to the target differential pressure by the pressure loss of the expansion side damping valve 15. And the thrust generated by the damper D increases accordingly. Here, the relationship between the thrust of the damper D is as follows: the area facing the expansion side chamber R1 of the piston 2 (the area obtained by subtracting the cross-sectional area of the rod 3 from the area of the piston 2) is the pressure receiving area, and the pressure receiving area of the piston 2 and the expansion side chamber It is a product of the pressure of R1. Therefore, in the graph shown in FIG. 3 in which the vertical axis represents the thrust direction of the damper D and the horizontal axis represents the expansion / contraction speed of the damper D, when the differential pressure is maximized by the electromagnetic valve V1, that is, the electromagnetic valve V1. The thrust of the damper D when the control pressure is maximized has the characteristic indicated by the line (1) in FIG.

  Next, a description will be given of a case where the damper D exerts a thrust force that pushes the piston 2 downward, and the damper D is contracted by an external force. Since the direction of thrust generated in the damper D is a direction in which the piston 2 is pushed down, it is necessary to supply liquid to the extension side chamber R1. In this case as well, the direction switching valve 9 is switched so as to adopt the expansion side supply position 9b, so that the expansion side chamber R1 is connected to the supply path 5 and the pressure side chamber R2 is connected to the reservoir R through the discharge path 6.

  When the damper D is contracting, the volume of the extension side chamber R1 increases. When the discharge flow rate of the pump 4 is equal to or larger than the volume increase amount of the expansion side chamber R1 per unit time, the discharge flow rate of the pump 4 is larger than the flow rate required in the expansion side chamber R1. In such a situation, the liquid discharged from the pump 4 flows into the expansion side chamber R1 through the expansion side check valve 16, and the liquid remaining from the discharge flow rate of the pump 4 without being absorbed in the expansion side chamber R1 is solenoid valve. It flows to the reservoir R through V1. Therefore, the pressure in the extension side chamber R1 is controlled to be equal to the pressure in the supply path 5. In the pressure side chamber R2 in which the other volume decreases, the volume-reduced liquid is discharged from the pressure side chamber R2 to the reservoir R via the pressure side damping valve 17 and the discharge path 6. Therefore, the liquid flow corresponding to the excess flow rate from the pump 4 and the liquid flow discharged from the pressure side chamber R2 are merged and returned to the reservoir R via the hydraulic motor Hm. The hydraulic motor Hm is driven and the generator G generates power.

  The pressure in the pressure side chamber R2 is higher than the pressure in the discharge path 6 by the amount of pressure loss that occurs when the liquid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17. Therefore, in this case, even if the solenoid valve V1 controls the actual differential pressure according to the target differential pressure, the differential pressure between the expansion side chamber R1 and the compression side chamber R2 is greater than the target differential pressure by the pressure loss of the compression side damping valve 17. And the thrust generated by the damper D decreases accordingly. From the above, when the damper D exerts thrust in the contraction direction, when the damper D contracts with external force and the discharge flow rate of the pump 4 exceeds the volume increase amount of the expansion side chamber R1 per unit time, the difference is generated in the solenoid valve V1. The thrust of the damper D when the pressure is maximized has the characteristic indicated by the line (2) in FIG.

  On the other hand, when the contraction speed of the damper D is high and the discharge flow rate of the pump 4 falls below the volume increase amount of the extension side chamber R1 per unit time, the liquid supply from the pump 4 is the volume per unit time of the extension side chamber R1. Can't keep up with the increase. As described above, when all of the liquid discharged from the pump 4 is absorbed in the extension side chamber R1, the liquid does not flow into the electromagnetic valve V1, and the suction check valve 11 is opened for the insufficient amount of liquid in the extension side chamber R1. The pressure is supplied from the pressure side chamber R2 whose volume decreases through the discharge passage 6 and the suction passage 10. The volume of the compression side chamber R2 that decreases is larger than the volume of the expansion side chamber R1 that increases by the volume that the rod 3 enters into the cylinder 1. Therefore, the liquid flow rate deficient in the expansion side chamber R1 is covered by the liquid flow rate discharged from the compression side chamber R2, and the volume of liquid that the rod 3 enters into the cylinder 1 moves to the reservoir R through the discharge path 6. Therefore, also in this case, the hydraulic motor Hm is rotationally driven and the generator G generates power. In such a situation, the pressure in the pressure side chamber R <b> 2 becomes higher than the pressure in the supply path 5 by the pressure loss due to the pressure side damping valve 17. Therefore, the damper D cannot exert a thrust in a direction in which the piston 2 is pushed down, and exerts a thrust in the opposite direction, that is, in a direction in which the piston 2 is pushed up. Therefore, when the damper D is contracted by an external force when the damper D tries to exert a thrust force that pushes down the piston 2, and the discharge flow rate of the pump 4 becomes less than the volume increase amount per unit time of the extension side chamber R 1, the damper D cannot exert thrust in the direction of pushing down the piston 2 downward. In this case, the differential pressure cannot be controlled by the electromagnetic valve V1, and the thrust of the damper D has the characteristic indicated by the line (3) in FIG. Therefore, when the differential pressure is maximized by the solenoid valve V1, the characteristic of the line (2) in FIG. 3 is obtained when the discharge flow rate of the pump 4 exceeds the volume increase amount per unit time of the expansion side chamber R1, and the discharge flow rate of the pump 4 Changes to the characteristic of the line (3) in FIG. 3 when the volume is less than the volume increase per unit time of the extension side chamber R1.

  Next, a case where the damper D exerts a thrust force that pushes the piston 2 upward and the damper D is contracted by an external force will be described. The direction of thrust generated in the damper D is a direction in which the piston 2 is pushed upward, and it is necessary to supply liquid to the pressure side chamber R2. Therefore, in this case, the controller C switches the direction switching valve 9 so as to adopt the pressure side supply position 9c, connects the pressure side chamber R2 to the supply path 5, and connects the extension side chamber R1 to the reservoir R through the discharge path 6. .

  When the damper D is in a contracting operation, the volume of the pressure side chamber R2 decreases, so that the reduced liquid is discharged from the pressure side chamber R2 through the pressure side damping valve 17 and passes through the electromagnetic valve V1 via the supply path 5. To the discharge path 6. On the other hand, the liquid corresponding to the volume expansion is supplied from the compression side chamber R2 through the discharge path 6 to the expansion side chamber R1 whose volume increases. At this time, the volume of liquid that the rod 3 enters into the cylinder 1 becomes excessive, and thus the liquid and the liquid discharged from the pump 4 flow to the reservoir R through the hydraulic motor Hm. Therefore, the hydraulic motor Hm is driven and the generator G generates power. Since the supply-side check valve 12 is provided, the liquid does not flow back to the pump 4 side even when the pressure in the supply path 5 is dynamically higher than the discharge pressure of the pump 4.

  In this case, the pressure in the pressure side chamber R2 becomes higher than the pressure in the supply path 5 by the amount of pressure loss that occurs when the liquid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17. Therefore, in this case, even if the solenoid valve V1 controls the actual differential pressure according to the target differential pressure, the differential pressure between the expansion side chamber R1 and the compression side chamber R2 is greater than the target differential pressure by the pressure loss of the compression side damping valve 17. And the thrust generated by the damper D increases accordingly. Therefore, in the graph shown in FIG. 3, the thrust of the damper D when the differential pressure is maximized by the electromagnetic valve V1 has the characteristic indicated by the line (4) in FIG.

  Further, a case will be described in which the damper D exerts a thrust force that pushes the piston 2 upward, and the damper D is extended by an external force. Since the direction of thrust generated in the damper D is a direction in which the piston 2 is pushed upward, it is necessary to supply liquid to the pressure side chamber R2. Therefore, in this case, the controller C switches the direction switching valve 9 so as to adopt the pressure side supply position 9c, connects the pressure side chamber R2 to the supply path 5, and connects the extension side chamber R1 to the reservoir R through the discharge path 6. .

  When the damper D is extended, the volume of the pressure side chamber R2 increases. However, when the discharge flow rate of the pump 4 is equal to or larger than the volume increase per unit time of the pressure side chamber R2, it is necessary in the pressure side chamber R2. The discharge flow rate of the pump 4 is larger than the flow rate. Therefore, the liquid discharged from the pump 4 flows into the pressure side chamber R2 through the pressure side check valve 18, and the liquid remaining from the discharge flow rate of the pump 4 without being absorbed in the pressure side chamber R2 passes through the electromagnetic valve V1 to the discharge path 6. To flow. Therefore, the pressure in the pressure side chamber R2 is equal to the pressure in the supply path 5. In the extension side chamber R1 in which the other volume is reduced, the volume-reduced liquid is discharged from the extension side chamber R1 to the reservoir R via the extension side damping valve 15 and the discharge path 6. Therefore, the liquid flow corresponding to the excess flow rate from the pump 4 and the liquid flow discharged from the extension side chamber R1 are merged and returned to the reservoir R via the hydraulic motor Hm, and the hydraulic motor Hm is driven to generate the generator G. Will generate electricity.

  The pressure in the extension side chamber R1 is higher than the pressure in the discharge path 6 by the amount of pressure loss that occurs when the liquid discharged from the extension side chamber R1 passes through the extension side damping valve 15. Therefore, in this case, even if the solenoid valve V1 controls the actual differential pressure according to the target differential pressure, the differential pressure between the expansion side chamber R1 and the compression side chamber R2 is equal to the target differential pressure by the pressure loss of the expansion side damping valve 15. And the thrust generated by the damper D also decreases accordingly. From the above, when causing the damper D to exert the thrust in the extension direction, if the damper D is extended by an external force and the discharge flow rate of the pump 4 exceeds the volume increase amount of the pressure side chamber R2 per unit time, the electromagnetic valve V1 The thrust of the damper D when the differential pressure is maximized has the characteristic indicated by the line (5) in FIG.

  On the other hand, the extension speed of the damper D is high, the discharge flow rate of the pump 4 falls below the volume increase per unit time of the pressure side chamber R2, and the liquid supply from the pump 4 is the volume per unit time of the pressure side chamber R2. Can't keep up with the increase. As described above, when all of the liquid discharged from the pump 4 is absorbed in the pressure side chamber R2, the liquid does not flow into the electromagnetic valve V1, and the suction check valve 11 is opened for the insufficient amount of liquid in the pressure side chamber R2. It is supplied from the extension side chamber R1 via the discharge path 6 and the suction path 10. The volume of the expansion side chamber R1 that decreases is smaller than the volume of the compression side chamber R2 that increases by the volume of the rod 3 withdrawing into the cylinder 1. When the liquid flow rate deficient in the pressure side chamber R2 can be covered only by the discharge flow rate of the pump 4 and the liquid flow rate discharged from the extension side chamber R1, the liquid flows from the damper D to the reservoir R through the discharge path 6. Therefore, also in this case, the hydraulic motor Hm is driven and the generator G can generate power. On the other hand, when the extension speed of the damper D is further increased and the liquid flow rate deficient in the pressure side chamber R2 cannot be covered only by the discharge flow rate of the pump 4 and the liquid flow rate from the expansion side chamber R1, the bypass passage side check valve 21 opens, Liquid is supplied from the reservoir R to the pressure side chamber R2 via the bypass passage Bi. In this case, the liquid does not pass through the hydraulic motor Hm, and the generator G does not generate power. Thus, when the extension speed of the damper D is high and the discharge flow rate of the pump 4 falls below the volume increase amount per unit time of the compression side chamber R2, the pressure in the expansion side chamber R1 is equal to the pressure loss due to the expansion side damping valve 15. Only the pressure in the discharge path 6 becomes higher. For this reason, the damper D cannot exert thrust in the direction in which the piston 2 is pushed upward, and exerts thrust in the opposite direction, that is, in the direction in which the piston 2 is pushed downward. Therefore, when the damper D is extended by the external force when trying to exert the thrust to push the piston 2 upward, and the discharge flow rate of the pump 4 becomes less than the volume increase amount per unit time of the compression side chamber R2, the damper D cannot exert thrust in the direction in which the piston 2 is pushed upward. In this case, the differential pressure cannot be controlled by the electromagnetic valve V1, and the thrust of the damper D has the characteristic indicated by the line (6) in FIG. Therefore, when the differential pressure is maximized by the solenoid valve V1, if the discharge flow rate of the pump 4 exceeds the volume increase per unit time of the pressure side chamber R2, the characteristic of the line (5) in FIG. When the pressure becomes less than the volume increase amount per unit time of the compression side chamber R2, the characteristic changes to the line (6) in FIG.

  From the above, by adjusting the valve opening degree of the electromagnetic valve V1, in FIG. 3, between the line connecting the lines (1) to (3) to the line connecting the lines (4) to (6). The thrust of the damper D can be varied within the range. Further, when the discharge flow rate of the pump 4 is supplied to the expansion side chamber R1 and the compression side chamber R2 by driving the pump 4, the discharge flow rate of the pump 4 is larger than the volume increase amount of the expansion chamber. In some cases, thrust can be exerted in the same direction as the expansion and contraction direction of the damper D.

  In each case described above, the characteristic that the thrust generated by the damper D varies depending on the expansion / contraction speed by the expansion side damping valve 15 and the compression side damping valve 17 functions as a function as a shock absorber. Therefore, this suspension device S1 can be regarded as equivalent to an actuator and a passive shock absorber interposed in parallel between the sprung member Bo and the unsprung member W. And according to this suspension apparatus S1, the function as this passive shock absorber is exhibited and the vibration of the unsprung member W can be suppressed.

  The damper D exhibits a characteristic that the thrust changes from the line (2) in FIG. 3 to the line (3) on the contraction side, and the thrust changes from the line (5) to the line (6) in FIG. Although the characteristic is shown, the change in the characteristic occurs very instantaneously, and the influence on the ride comfort is slight.

  Next, the operation of the suspension device S1 when the pump 4 is stopped and not driven will be described. Also in this case, four cases can be considered if the direction in which the damper D is expanded and contracted by a disturbance and the direction in which the damper D generates a thrust are divided into cases.

  First, a case where the damper D exerts a thrust force that pushes the piston 2 downward and the damper D is extended by an external force will be described. The direction of thrust generated in the damper D is a direction in which the piston 2 is pushed down. Therefore, the controller C switches the direction switching valve 9 so as to adopt the expansion side supply position 9b, connects the expansion side chamber R1 to the supply path 5, and connects the pressure side chamber R2 to the reservoir R through the discharge path 6.

  When the damper D is extended, the volume of the extension side chamber R1 is reduced. Therefore, the reduced liquid is discharged from the extension side chamber R1 through the extension side damping valve 15 and passes through the electromagnetic valve V1 via the supply path 5. And flows to the discharge path 6. On the other hand, the liquid corresponding to the volume expansion is supplied from the expansion side chamber R1 and the reservoir R via the discharge path 6 to the pressure side chamber R2 whose volume increases. In this case, since the bypass passage side check valve 21 is opened and the liquid passes through the bypass passage Bi, the hydraulic motor Hm is not driven and the generator G stops and does not generate power. In addition, since the supply side check valve 12 is provided, the liquid does not flow to the pump 4 side.

  The differential pressure between the supply path 5 and the discharge path 6 is controlled to the target differential pressure by the electromagnetic valve V1, but the pressure in the extension side chamber R1 is such that the liquid discharged from the extension side chamber R1 passes through the extension side damping valve 15. It becomes higher than the pressure of the supply path 5 by the amount of pressure loss that occurs. Therefore, in the graph shown in FIG. 4 in which the vertical axis represents the direction of the thrust of the damper D and the horizontal axis represents the expansion / contraction speed of the damper D, the thrust of the damper D when the differential pressure is maximized by the solenoid valve V1 is The characteristic indicated by the line (7) in FIG.

  Next, a description will be given of a case where the damper D exerts a thrust force that pushes the piston 2 downward, and the damper D is contracted by an external force. Although the pump 4 is in a stopped state and no liquid is supplied from the pump 4, the direction of the thrust generated by the damper D is a direction in which the piston 2 is pushed down. Therefore, the controller C switches the direction switching valve 9 so as to adopt the expansion side supply position 9 b, connects the expansion side chamber R 1 to the supply path 5, and connects the pressure side chamber R 2 to the reservoir R through the discharge path 6.

  When the damper D is contracted, the volume of the expansion side chamber R1 increases. However, since the pump 4 is stopped, no liquid flows through the solenoid valve V1, and the amount of liquid deficient in the expansion side chamber R1 is sucked. The check valve 11 is opened and supplied from the pressure side chamber R2 through the discharge passage 6 and the suction passage 10. In this situation, the pressure in the extension chamber R1 is substantially equal to the pressure in the supply path 5. The liquid discharged from the pressure side chamber R2 with the other volume decreasing flows into the expansion side chamber R1 via the pressure side damping valve 17 and the discharge path 6, and the flow rate for the volume at which the rod 3 enters the cylinder 1 is reduced to the reservoir R. To flow. Therefore, in this case, since the liquid passes through the hydraulic motor Hm, the generator G generates power. The pressure in the pressure side chamber R2 is higher than the pressure in the discharge path 6 by the amount of pressure loss that occurs when the liquid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17. Therefore, the damper D cannot exert thrust in the direction in which the piston 2 is pushed down, but exerts thrust in the opposite direction, that is, in the direction in which the piston 2 is pushed upward. From the above, when trying to cause the damper D to exert a thrust force to push the piston 2 downward, when the damper D is contracted by an external force and the pump 4 is stopped, the piston 2 is moved downward. The thrust cannot be exerted in the direction of pushing down. And the differential pressure cannot be controlled by the electromagnetic valve V1, and the thrust of the damper D has the characteristic indicated by the line (8) in FIG. This brings about an effect equivalent to controlling the compression side damping force to the lowest damping force in the damping force variable damper.

  Next, a case where the thrust that pushes the piston 2 upward is exerted on the damper D and the damper D is contracted by an external force will be described. The direction of thrust generated in the damper D is a direction in which the piston 2 is pushed upward. Therefore, the controller C switches the direction switching valve 9 so as to adopt the pressure side supply position 9 c, connects the pressure side chamber R 2 to the supply path 5, and connects the extension side chamber R 1 to the reservoir R through the discharge path 6.

  When the damper D is in a contracting operation, the volume of the pressure side chamber R2 decreases, so that the reduced liquid is discharged from the pressure side chamber R2 through the pressure side damping valve 17 and passes through the electromagnetic valve V1 via the supply path 5. To the discharge path 6. On the other hand, the liquid corresponding to the volume expansion is supplied from the compression side chamber R2 through the discharge path 6 to the expansion side chamber R1 whose volume increases. In this case, since the rod 3 enters the cylinder 1, the liquid discharged from the pressure side chamber R2 cannot be absorbed by the extension side chamber R1 alone, and excess liquid flows to the reservoir R through the hydraulic motor Hm. Therefore, the hydraulic motor Hm is driven and the generator G generates power. In addition, since the supply side check valve 12 is provided, the liquid does not flow to the pump 4 side.

  Since the differential pressure between the supply passage 5 and the discharge passage 6 is controlled to the target differential pressure by the electromagnetic valve V1, the pressure in the pressure side chamber R2 is determined when the liquid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17. It becomes higher than the pressure in the supply path 5 by the amount of pressure loss that occurs. Therefore, in the graph shown in FIG. 4, the thrust of the damper D when the control pressure of the solenoid valve V1 is maximized has the characteristic indicated by the line (9) in FIG.

  Subsequently, a case where the damper D exerts a thrust force that pushes the piston 2 upward, and the damper D is extended by an external force will be described. Although the pump 4 is in a stopped state and no liquid is supplied from the pump 4, the direction of thrust generated by the damper D is a direction in which the piston 2 is pushed upward. Therefore, the controller C switches the direction switching valve 9 so as to adopt the pressure side supply position 9 c, connects the pressure side chamber R 2 to the supply path 5, and connects the extension side chamber R 1 to the reservoir R through the discharge path 6.

  When the damper D is extended, the volume of the pressure side chamber R2 increases. However, since the pump 4 is stopped, liquid does not flow to the solenoid valve V1, and an insufficient amount of liquid is sucked in the pressure side chamber R2. The check valve 11 is opened and supplied from the extension side chamber R1 via the discharge path 6 and the suction path 10. In this situation, the pressure in the pressure side chamber R2 is substantially equal to the pressure in the supply path 5. The liquid discharged from the expansion side chamber R1 in which the other volume is reduced flows to the compression side chamber R2 via the expansion side damping valve 15 and the discharge path 6. In the pressure side chamber R2, since the volume of the liquid in which the rod 3 retreats from the cylinder 1 is insufficient, the insufficient amount of liquid is supplied from the reservoir R through the supply path 5 to the pressure side chamber R2. Therefore, in this case, since the bypass passage side check valve 21 is opened and the liquid traveling from the reservoir R to the pressure side chamber R2 moves around the hydraulic motor Hm, the hydraulic motor Hm is not driven and the generator is driven. G stops and does not generate electricity. The pressure in the extension side chamber R1 is higher than the pressure in the discharge path 6 by the amount of pressure loss that occurs when the liquid discharged from the extension side chamber R1 passes through the extension side damping valve 15. Therefore, the damper D cannot exert a thrust in the direction in which the piston 2 is pushed up, but exerts a thrust in the opposite direction, that is, in a direction in which the piston 2 is pushed down. From the above, when trying to cause the damper D to exert a thrust force that pushes the piston 2 upward, when the damper D is extended by an external force and the pump 4 is stopped, the piston 2 is moved upward. The thrust cannot be exerted in the direction of pushing up. And the differential pressure cannot be controlled by the electromagnetic valve V1, and the thrust of the damper D has the characteristic indicated by the line (10) in FIG. This brings about an effect equivalent to controlling the extension side damping force to the lowest damping force in the damping force variable damper.

  If the differential pressure is adjusted by the solenoid valve V1, the damper D adjusts the extension side damping force in the first quadrant in FIG. 4 within the range from the line (7) to the line (10) (extension side output possible range). In the third quadrant in FIG. 4, the compression side damping force can be adjusted in the range from line (8) to line (9) (pressure side output possible range).

  Normally, in a semi-active suspension, skyhook control is executed according to the Karnop law using a damping force variable damper. Therefore, when the extension side damping force (force in the direction of pushing down the piston) is required, the damping force of the damping force variable damper is controlled to the damping force that can obtain the target thrust during the extension operation, and the extension side damping force during the contraction operation. Therefore, the lowest damping force is controlled to the compression side. Also, when compression side damping force (force in the direction of pushing up the piston) is required, the damping force of the damping force variable damper is controlled to the damping force that can obtain the target thrust during contraction operation, and the compression side damping force is obtained during extension operation. It is controlled so as to exhibit the lowest damping force toward the extension side. On the other hand, in the suspension device S1 of the present invention, when the damper D is intended to exert a thrust in the contraction direction when the pump 4 is stopped, the damper D is adjusted with a thrust adjusted within the extension-side output possible range when extended. And exerts the lowest thrust in the extension direction when contracted. On the other hand, when the damper D is intended to exert a thrust in the expansion direction when the pump 4 is stopped, the damper D exhibits a thrust that is adjusted within the stretchable output range during contraction, and is most in the contraction direction during expansion. Delivers low thrust. Therefore, the suspension device S1 of the present invention automatically exhibits the same function as the semi-active suspension when the pump 4 is stopped. This is because even if the pump 4 is being driven, the suspension device S1 automatically functions as a semi-active suspension when the discharge flow rate of the pump 4 becomes less than the volume increase amount of the expansion side chamber R1 or the compression side chamber R2. Means. The suspension device S1 automatically functions as a semi-active suspension because the supply side check valve 12 is provided so that the liquid is supplied to the pump 4 side even when the pressure in the supply path 5 is dynamically higher than the discharge pressure of the pump 4. This is because it was designed not to flow backward.

  Finally, the operation of the suspension apparatus S when the energization to the motor 13, the direction switching valve 9 and the electromagnetic valve V1 of the suspension apparatus S1 cannot be performed due to some abnormality will be described. Such failures include, for example, when the motor 13, the direction switching valve 9 and the electromagnetic valve V1 cannot be energized, and when the controller C and the driver device Dr are abnormal, the motor 13, the direction switching valve 9 and The case where the energization to the solenoid valve V1 is stopped is also included.

  At the time of failure, the energization to the motor 13, the direction switching valve 9 and the electromagnetic valve V1 is stopped or cannot be energized, the pump 4 is stopped, the control pressure of the electromagnetic valve V1 is minimized, and the direction switching is performed. The valve 9 is biased by the spring 9d and assumes the extended side supply position 9b.

  In this state, when the damper D is extended by an external force, the volume of the extension side chamber R1 is reduced. Therefore, the reduced liquid is discharged from the extension side chamber R1 through the extension side damping valve 15 and is electromagnetically transmitted through the supply path 5. It flows to the reservoir R through the valve V1. In addition, since the supply side check valve 12 is provided, the liquid does not flow to the pump 4 side. On the other hand, the liquid corresponding to the volume expansion is supplied from the reservoir R through the discharge path 6 to the pressure side chamber R2 whose volume increases.

  Although the liquid discharged from the extension side chamber R1 passes through the electromagnetic valve V1, the pressure of the supply path 5 is almost equal to the reservoir because the electromagnetic valve V1 has a characteristic that hardly gives resistance to the flow that passes when the solenoid valve V1 is not energized. It becomes equal to the pressure of R. Accordingly, the pressure in the expansion side chamber R1 is higher than the pressure in the supply path 5 by the amount of pressure loss generated when the liquid discharged from the expansion side chamber R1 passes through the expansion side damping valve 15. It becomes higher than the pressure of R.

  Therefore, the thrust of the damper D becomes a force obtained by multiplying the pressure corresponding to the pressure loss by the expansion side damping valve 15 by the pressure receiving area of the expansion side chamber R1 of the piston 2, and in the graph shown in FIG. ).

  On the other hand, when the damper D is contracted by an external force, the volume of the pressure side chamber R2 decreases, so that the reduced liquid is discharged from the pressure side chamber R2 through the pressure side damping valve 17 and flows to the reservoir R. On the other hand, the liquid corresponding to the volume expansion is supplied from the reservoir R through the suction passage 10 and the suction check valve 11 to the expansion side chamber R1 whose volume increases. In addition, since the supply side check valve 12 is provided, the liquid does not flow to the pump 4 side.

  Therefore, the pressure in the pressure side chamber R2 becomes higher than the pressure in the reservoir R by the amount of pressure loss that occurs when the liquid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17. Accordingly, the thrust of the damper D is a force obtained by multiplying the pressure commensurate with the pressure loss by the pressure side damping valve 17 by the pressure receiving area of the pressure side chamber R2 of the piston 2, and in the graph shown in FIG. 5, the line (12) in FIG. It becomes the characteristic shown by.

  Thus, in the state where the suspension device S has failed, the damper D functions as a passive damper and suppresses the vibration of the sprung member Bo and the unsprung member W, so that fail-safe operation is reliably performed in the event of a failure. Is called.

  In the suspension device S1 of the present invention, when one or both of the liquid discharged from the cylinder 1 or the excess liquid out of the liquid flow rate discharged by the pump 4 is returned to the reservoir R, the hydraulic motor Hm is driven. Can generate electricity. Although not shown, the power obtained by this power generation is stored in a storage battery and supplied to the controller C, the driver device Dr, the motor 13, the electromagnetic valve V1, the direction switching valve 9 or an external device not shown as required. May be. Therefore, according to the suspension device S1 of the present invention, the vibration energy of the suspension can be regenerated and taken out as electric energy, and the electric power obtained by the power generation can be supplied to the consuming member in the suspension device S1 such as the motor 13.

  As described above, the suspension device S1 of the present invention is connected to the damper D, the pump 4, the reservoir R connected to the suction side of the pump 4, the supply path 5 connected to the discharge side of the pump 4, and the reservoir R. Discharge path 6, extension side passage 7 connected to extension side chamber R 1 of damper D, pressure side path 8 connected to pressure side chamber R 2 of damper D, direction switching valve 9, supply path 5 and discharge path 6, an electromagnetic valve V <b> 1 provided between the hydraulic pressure motor 6, a hydraulic motor Hm provided in the discharge path 6, and a generator G driven by the hydraulic motor Hm. If comprised in this way, the hydraulic motor Hm can be driven using the flow of the liquid which returns to the reservoir | reserver R, and the generator G can be driven, and the regeneration which acquires an electrical energy from vibration energy is attained.

  Further, in the suspension device S1 of this example, the hydraulic motor Hm is provided in the discharge path, and the supply side pressure sensor 31 that detects the pressure of the supply path 5 and the discharge side pressure that detects the pressure of the discharge path 6 are provided. A sensor 32, a bypass passage Bi provided in the discharge passage 6 and bypassing the hydraulic motor Hm, and a bypass passage provided in the bypass passage Bi and permitting only a liquid flow from the reservoir R side toward the direction switching valve 9 side. And a side check valve 21. In the suspension device S1 of the present example, the supply side pressure sensor 31, the discharge side pressure sensor 32, and the bypass passage side check valve 21 can be installed to control the thrust generated by the damper D while discharging the hydraulic motor Hm. 6 can be installed. In the suspension device S1 of this example configured as described above, when the liquid returns to the reservoir R, the hydraulic motor Hm is always driven and the generator G generates electric power. Thus, electric energy can be obtained.

  Further, in the suspension device S1 of the present example, the extension provided in the extension side passage 7 gives resistance to the flow from the extension side chamber R1 toward the direction switching valve 9, and allows the extension in the opposite direction. A pressure-side damping element VC that is provided in the pressure-side passage 8 and that gives resistance to the flow from the pressure-side chamber R2 toward the direction switching valve 9 and allows the flow in the opposite direction; A suction passage 10 that connects the exhaust passage 6 and the suction passage 10, a suction check valve 11 that is provided in the middle of the suction passage 10 and allows only the flow of liquid from the discharge passage 6 toward the supply passage 5, and in the middle of the supply passage 5. A supply-side check valve 12 is provided between the solenoid valve V1 and the pump 4 and allows only a flow from the pump 4 side toward the solenoid valve V1 side. According to the suspension device S1 configured as described above, the pump 4 is driven in a scene where not only the damper D is actively expanded and contracted to function as an active suspension but also the thrust as a semi-active suspension is expected to be exhibited. Is no longer required. Therefore, in the suspension device S1 of this example, it is sufficient to drive the pump 4 only when the pump 4 is necessary, so that energy consumption is extremely reduced, and the suspension device S1 can automatically function as a semi-active suspension.

  Further, in the suspension device S1 of this example, the extension side damping element VE is provided in parallel with the extension side damping valve 15 and the extension side damping valve 15 that provide resistance to the flow from the extension side chamber R1 toward the direction switching valve 9. A compression side damping valve 16 that allows only a flow from the direction switching valve 9 toward the expansion side chamber R1, and the pressure side damping element VC provides resistance to the flow from the pressure side chamber R2 toward the direction switching valve 9. 17 and a pressure side check valve 18 that is arranged in parallel with the pressure side damping valve 17 and allows only a flow from the direction switching valve 9 toward the pressure side chamber R2. In this way, when supplying the liquid from the pump 4 to the extension side chamber R1 or the pressure side chamber R2, the liquid is supplied to the extension side chamber R1 or the pressure side chamber R2 through the extension side check valve 16 or the pressure side check valve 18 with almost no resistance. it can. Therefore, in the suspension device S1, the load on the pump 4 can be reduced when the expansion / contraction direction of the damper D coincides with the direction of the generated thrust. Further, when the liquid is discharged from the expansion side chamber R1 or the pressure side chamber R2, resistance is given to the flow of the liquid passing through the expansion side attenuation valve 15 or the pressure side attenuation valve 17, so that the pressure in the expansion side chamber R1 or the pressure side chamber R2 A large thrust can be obtained by making the pressure equal to or higher than the control pressure of the electromagnetic valve V1. Therefore, even if the thrust of the solenoid 20e in the electromagnetic valve V1 is reduced, a large thrust can be generated in the suspension device S1. From this, according to the suspension device S1 of this example, the electromagnetic valve V1 can be reduced in size and the cost can be reduced.

  Note that the extension side damping element VE and the compression side damping element VC may give resistance to the flow of the liquid regardless of the direction in which the liquid flows. In this case, the extension side check valve 16 and the pressure side check valve 18 can be omitted if the extension side attenuation valve 15 and the pressure side attenuation valve 17 allow bidirectional flow. Even in that case, the energy consumption is reduced because the driving of the pump 4 is not essential in the scene where the suspension device S1 is expected to exhibit the thrust as a semi-active suspension.

<Second Embodiment>
Next, the suspension device S2 in the second embodiment will be described. As shown in FIG. 6, the suspension device S <b> 2 of the second embodiment includes a damper D, a pump 4, a reservoir R connected to the suction side of the pump 4, and a supply connected to the discharge side of the pump 4. A passage 5, a discharge passage 6 connected to the reservoir R, an extension side passage 7 connected to the extension side chamber R 1 of the damper D, a pressure side passage 8 connected to the pressure side chamber R 2 of the damper D, and a direction switching valve 9. And a solenoid valve V2 provided in the control passage 19 connecting the supply passage 5 and the discharge passage 6, a hydraulic motor Hm provided downstream of the solenoid valve V2 in the control passage 19, and the hydraulic motor Hm. And a generator G.

  The suspension device S2 in this example is different from the suspension device S1 of the first embodiment in that the hydraulic motor Hm is provided in the middle of the control passage 19 and downstream of the electromagnetic valve V2, and the bypass passage. Bi differs in that the bypass passage side check valve 21 and the discharge side pressure sensor 32 are abolished.

In this suspension device S2, the discharge path 6 communicates with the reservoir R without the hydraulic motor Hm, and is always maintained at the reservoir pressure. Thus, the pressure P _L of the discharge channel 6 because the reservoir pressure, it is not necessary to correct the target difference pressure in response to pressure changes in the discharge path 6. Thus, the suspension device D2 of the present embodiment, the differential pressure of the exhaust passage 6 and the supply path 5 by detecting a feed-side pressure sensor 31 only the pressure P _H of the supply path 5 and there is no need to detect the pressure of the exhaust passage 6 And the thrust of the damper D can be controlled as described above. Even in the suspension device S2 of this example, the operations for switching the position of the direction switching valve 9 when the damper D exerts thrust, adjusting the valve opening of the electromagnetic valve V2, and driving the pump 4 are as follows. This is the same as the suspension device S1.

  In the suspension device S2 of this example, when the liquid flows through the control passage 19, the hydraulic motor Hm is driven and the generator G generates power. That is, power generation is possible in a situation where the liquid passes through the electromagnetic valve V2. When the pump 4 is being driven, the generator G generates power because the liquid passes through the solenoid valve V2 in a state where the liquid flow rate deficient in the cylinder 1 can be covered by the discharge flow rate of the pump 4. Further, when the pump 4 is stopped, when the expansion / contraction direction of the damper D is different from the direction in which the thrust is exerted, the liquid passes through the electromagnetic valve V2, so that the generator G generates power.

  Thus, in the suspension device S2 of this example, the damper D, the pump 4, the reservoir R connected to the suction side of the pump 4, the supply path 5 connected to the discharge side of the pump 4, and the reservoir R are connected. Discharge path 6, extension side passage 7 connected to extension side chamber R 1 of damper D, pressure side path 8 connected to pressure side chamber R 2 of damper D, direction switching valve 9, supply path 5 and discharge path 6 is provided with a solenoid valve V2 provided in the control passage 19 for connecting to the hydraulic passage 6, a hydraulic motor Hm provided downstream of the solenoid valve V2 in the control passage 19, and a generator G driven by the hydraulic motor Hm. Composed. If comprised in this way, the hydraulic motor Hm can be driven using the flow of the liquid which passes the electromagnetic valve V2, and the generator G can be driven, and the regeneration which acquires an electrical energy from vibration energy is attained.

  Further, in the suspension device S2 of this example, the bypass passage Bi, the bypass passage side check valve 21 and the discharge side pressure sensor 32 need not be provided, so that the number of parts is reduced and the cost of the entire device is reduced.

  The electromagnetic valve V2 is an electromagnetic throttle valve, and can control the pressure of the supply path 5, so that only the supply side pressure sensor may be used for controlling the thrust of the damper D. In contrast, the electromagnetic valve V2 may be an electromagnetic pressure control valve. In this case, the electromagnetic valve V2 controls the differential pressure between the upstream and downstream, and a pressure loss occurs when the liquid passes through the hydraulic motor Hm. Therefore, the electromagnetic valve V2 is between the electromagnetic valve V2 and the hydraulic motor Hm. It is necessary to detect the pressure. When the electromagnetic valve V2 is an electromagnetic throttle valve, the thrust of the damper D can be controlled by using only the supply side pressure sensor. However, when the electromagnetic pressure control valve is used, the bypass passage Bi and the bypass passage side check valve 21 can be eliminated. Two pressure sensors are required to control the thrust of the damper D.

  This is the end of the description of the embodiments of the present invention, but the scope of the present invention is not limited to the details shown or described.

DESCRIPTION OF SYMBOLS 1 ... Cylinder, 2 ... Piston, 4 ... Pump, 5 ... Supply path, 6 ... Discharge path, 7 ... Extension side path, 8 ... Pressure side path, 9 ... Direction switching valve, 10 ... suction passage, 11 ... suction check valve, 12 ... supply side check valve, 15 ... extension side damping valve, 16 ... extension side check valve, 17 ... -Pressure side damping valve, 18 ... Pressure side check valve, 19 ... Control passage, 21 ... Bypass passage side check valve, 31 ... Supply side pressure sensor, 32 ... Discharge side pressure sensor, Bi ..Bypass passage, D ... Damper, G ... Generator, Hm ... Hydraulic motor, R ... Reservoir, R1 ... Extension side chamber, R2 ... Pressure side chamber, S1, S1 ..Suspension devices, V1, V2 ... solenoid valves, VC ... compression side damping elements, VE ... extension side damping elements

Claims (5)

A damper having a cylinder and a piston that is movably inserted into the cylinder and divides the cylinder into an extension side chamber and a pressure side chamber;
A pump,
A reservoir connected to the suction side of the pump;
A supply path connected to the discharge side of the pump;
A discharge path connected to the reservoir;
An extension passage connected to the extension chamber;
A pressure side passage connected to the pressure side chamber;
A direction switching valve for selecting one of the extension side passage and the pressure side passage and connecting the other side of the extension side passage and the pressure side passage to the discharge passage, and connecting to the supply passage;
A solenoid valve provided between the supply path and the discharge path;
A hydraulic motor provided downstream of the solenoid valve or in the discharge path;
A suspension device comprising: a generator driven by the hydraulic motor. The solenoid valve is provided in a control passage that connects the supply passage and the discharge passage,
The suspension apparatus according to claim 1, wherein the hydraulic motor is provided downstream of the electromagnetic valve in the control passage. The hydraulic motor is provided in the discharge path;
A supply-side pressure sensor for detecting the pressure of the supply path;
A discharge-side pressure sensor for detecting the pressure in the discharge path;
A bypass passage provided in the discharge passage and bypassing the hydraulic motor;
The suspension device according to claim 1, further comprising a bypass passage side check valve provided in the bypass passage and allowing only a liquid flow from the reservoir side toward the direction switching valve side. An extension-side damping element that is provided in the extension-side passage and that provides resistance to the flow from the extension-side chamber toward the direction switching valve, and allows the opposite-direction flow;
A pressure-side damping element that is provided in the pressure-side passage, provides resistance to the flow from the pressure-side chamber toward the direction switching valve, and permits the flow in the opposite direction;
A suction passage connecting the supply passage and the discharge passage;
A suction check valve that is provided in the middle of the suction passage and allows only the flow of liquid from the discharge passage to the supply passage;
A supply-side check valve provided between the electromagnetic valve and the pump in the middle of the supply path and allowing only a flow from the pump side toward the electromagnetic valve side. Item 4. The suspension device according to any one of Items 1 to 3. The extension side damping element includes only an extension side damping valve that provides resistance to a flow from the extension side chamber toward the direction switching valve, and a flow that is parallel to the extension side attenuation valve and that flows from the direction switching valve toward the extension side chamber. The pressure side damping element includes a pressure side damping valve that provides resistance to a flow from the pressure side chamber toward the direction switching valve, and the direction switching valve in parallel with the pressure side damping valve. The suspension device according to claim 4, further comprising: a pressure side check valve that allows only a flow from the pressure side chamber toward the pressure side chamber.

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