JP2019093822A - Suspension device - Google Patents

Abstract

To provide a suspension device which prevents that control of a control valve becomes hard, and suppresses valve vibration of the control valve, and thus, can stably control the control valve.SOLUTION: This suspension device S comprises: an actuator AC including an extension side chamber R1 and a compression side chamber R2; a pump 4; a reservoir R; a feed passage 5 connected to the pump 4; an exhaust passage 6 connected to the reservoir R; an extension side passage 7 connected to the extension side chamber R1; a compression side passage 8 connected to the compression side chamber R2; a changeover valve 9 which selectively connects one of the extension side passage 7 and the compression side passage 8 to the feed passage 5 and connects the other of the extension side passage 7 and the compression side passage 8 to the exhaust passage 6; a control passage 19 at a middle of which a control valve V, which can adjust a pressure in the feed passage 5, is provided; and a flow priority valve FPV which is provided at a middle of the control passage 19 and on an upstream side with respect to the control valve V, permits only passage of a fluid of a prescribed flow quantity or less, and discharges the fluid of an excess flow quantity exceeding the prescribed flow quantity to the reservoir R.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a suspension device.

  As this type of suspension apparatus, for example, there is one that functions as an active suspension interposed between a vehicle body of a vehicle and an axle, and more specifically, the cylinder is movably inserted into the cylinder and the cylinder to be in the cylinder A suspension body including a piston that divides the pressure chamber into an expansion side chamber and a pressure side chamber, a rod connected to the piston, a pump, a reservoir connected to the suction side of the pump, and a supply path connected to the discharge side of the pump A discharge passage connected to the reservoir, an expansion side passage connected to the expansion side chamber, a pressure side passage connected to the pressure side chamber, and one of the expansion side passage and the pressure side passage selectively connected to the supply path; A control valve that connects the other of the side passage and the pressure side passage to the discharge passage, and a control valve that connects the supply passage and the discharge passage and that can adjust the pressure of the supply passage according to the supplied current There is one configured to include a passage, a suction passage for allowing only flow of fluid to the supply passage from the discharge passage as well as connecting the discharge passage and the supply passage (for example, Patent Document 1).

  In such a suspension device, the destination of the fluid discharged by the pump can be switched between the expansion side chamber and the pressure side chamber by the switching valve, and when the fluid discharged by the pump is supplied to the expansion side chamber, the piston moves downward. As a result, the suspension body is contracted, and when it is supplied to the pressure side chamber, the piston moves upward to extend the suspension body. Further, the pressure of the supply passage, that is, the pressure of the fluid which the pump discharges into the cylinder can be adjusted by the control valve, so that the magnitude of the thrust in the extension direction or the contraction direction of the suspension body can be adjusted.

JP 2016-88358

  In such a suspension device, the suspension main body may expand and contract under external force due to the unevenness of the road surface while the vehicle is traveling.

  Then, in the case where the suspension device exerts a thrust that pushes the piston downward and the suspension main body is operated to expand by an external force, the volume of the expansion side chamber becomes small, so the excess fluid in the expansion side chamber is the cylinder It is discharged outside. At this time, the fluid discharged from the expansion chamber is discharged to the discharge channel through the expansion channel, the supply channel, and the control channel. Further, since the supply passage also communicates with the control passage, the fluid discharged from the pump also passes through the control passage.

  Also, in the case of causing the suspension device to exert a thrust that pushes the piston upward, the fluid excess in the pressure side chamber is also discharged through the control passage even when the suspension body is contracted by an external force. The fluid discharged into the passage and discharged from the pump also passes through the control passage.

  As described above, in the conventional suspension device, when the suspension device expands and contracts due to an external force, a large flow rate obtained by totaling the flow rate of the fluid discharged out of the cylinder and the flow rate of the fluid discharged from the pump is provided to the control valve provided in the control passage. It may flow.

  In addition, when the suspension device exerts a thrust that pushes the piston downward, if the suspension main body expands and contracts due to an external force, there is no problem if the discharge flow rate of the pump exceeds the volume increase of the expansion side chamber or the pressure side chamber. However, when the discharge flow rate of the pump falls below the volume increase, all the fluid discharged from the pump is absorbed in the expansion side chamber or the pressure side chamber, and the fluid does not flow to the control valve.

  Thus, in the conventional suspension system, the flow rate of fluid passing through the control valve fluctuates significantly from zero to a large flow rate.

  Therefore, in the conventional suspension device, when a large flow of fluid flows through the control valve, a huge fluid force may act on the control valve to make control of the control valve difficult, or the flow rate fluctuation is large. In the vicinity of the closing of the valve of the control valve, the pressure change with respect to the displacement of the valve becomes large, which may cause valve vibration.

  Therefore, in the present invention, it is an object of the present invention to provide a suspension device capable of stably controlling a control valve by preventing difficulty in control of the control valve and suppressing valve vibration of the control valve.

  Means for solving the above problems include an actuator including a piston which is movably inserted in a cylinder and divides the inside of the cylinder into an expansion side chamber and a compression side chamber, and a reservoir connected to the suction side of the pump A supply passage connected to the discharge side of the pump, a discharge passage connected to the reservoir, an expansion side passage connected to the expansion side chamber, a pressure side passage connected to the pressure side chamber, and the expansion side A selector valve selectively connecting one of the passage and the pressure side passage to the supply passage and connecting the other of the extension side passage and the pressure side passage to the discharge passage, and the pressure of the supply passage according to the supply current. A control passage provided with an adjustable control valve in the middle, a suction passage connecting the supply passage and the discharge passage, and a fluid flow provided from the discharge passage to the supply passage provided in the middle of the suction passage Suction that only allows A check valve, a supply-side check valve provided midway in the supply passage between the control valve and the pump and permitting only the flow of fluid from the pump side to the control valve side; A flow priority valve is provided on the upstream side of the control valve in the middle of the passage to allow only the passage of fluid having a predetermined flow rate or less, and the excess flow rate exceeding the predetermined flow rate is discharged to the reservoir. It is characterized by

  Further, the flow priority valve connects the upstream and downstream of the control passage and has a restricted passage having an orifice for resisting the flow of the passing fluid, and the reservoir branched from upstream from the orifice of the restricted passage. , A valve seat provided in the middle of the return passage, a valve body seated on the valve seat for opening and closing the return passage, and biasing the valve body toward the valve seat And the pressure on the upstream side of the control passage is applied to the valve body in the valve opening direction, and the pressure on the downstream side of the control passage is applied in the valve closing direction, When the valve seat is seated on the valve seat, the pressure receiving area of the pressure received from the upstream side of the control passage in the valve body is equal to the pressure receiving area of the pressure received from the downstream side of the control passage. According to this configuration, the pressure receiving area for receiving pressure from the upstream side of the control passage in the valve body and the pressure receiving area for receiving pressure from the downstream side of the control passage are equal, so even if the valve opening pressure of the control valve changes The pressing force does not change, and the flow rate of the fluid flowing to the control valve can be made constant.

  Further, an orifice may be provided in the control passage in parallel with the control valve. According to this configuration, the flow priority valve functions as a relief valve because the control passage is communicated with the discharge passage through the orifice even if the control valve is mechanically broken and is in the closed / closed state. Relieve pressure.

  The expansion side damping element is provided in the expansion side passage to provide resistance to the flow from the expansion side chamber toward the switching valve and allows the flow in the opposite direction, and the expansion side damping element is provided in the pressure side passage. A pressure damping element may be provided to provide resistance to the flow from the pressure chamber to the switching valve and allow for flow in the opposite direction. According to this configuration, since the suspension device functions not only as an active suspension but also as a semi-active suspension, driving of the pump is not essential in situations where the exertion of thrust as a semi-active suspension is expected, and the energy of the suspension device Consumption is reduced.

  According to the suspension device of the present invention, since the flow priority valve can set the upper limit of the flow rate of the fluid passing through the control valve, excessive fluid force does not act on the control valve, and the control valve can be stably controlled.

It is a figure showing a suspension device concerning this embodiment. FIG. 2 is a view showing a state in which the suspension device in the present embodiment is interposed between a vehicle body and wheels of a vehicle. It is a figure showing the flow priority valve concerning this embodiment with a circuit diagram. It is a figure showing a concrete example of a flow priority valve concerning this embodiment. It is the figure which showed the relationship between the flow volume of the fluid which passes the control valve of the suspension apparatus which concerns on this Embodiment, and the flow volume of the fluid discharged | emitted by the bypass. It is the figure which showed the characteristic of the thrust at the time of making the suspension apparatus in this Embodiment function as an active suspension. It is the figure which showed the characteristic of the thrust at the time of making the suspension apparatus in this Embodiment function as a semi active suspension. It is a figure showing the characteristic of the thrust at the time of failure of the suspension device concerning this embodiment. It is the figure which expanded and showed a part of modification of the suspension apparatus which concerns on this Embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings. Like numbers refer to like parts throughout the several views.

  As shown in FIG. 1, a suspension device S according to the present embodiment includes a cylinder 1 and a piston 2 movably inserted into the cylinder 1 to divide the inside of the cylinder 1 into an expansion chamber R1 and a compression chamber R2. And a pump R, a reservoir R connected to the suction side of the pump 4, and a fluid pressure circuit FC provided between the actuator AC and the pump 4 and the reservoir R. .

  The fluid pressure circuit FC of this example includes the supply passage 5 connected to the discharge side of the pump 4, the discharge passage 6 connected to the reservoir R, the expansion passage 7 connected to the expansion chamber R1, and the pressure chamber R2. Side of the expansion side passage 7 and the pressure side passage 8 selectively connected to the supply passage 5 and the switching valve 9 of the other side of the extension side passage 7 and the pressure side passage 8 to the discharge passage 6 And a control passage 19 provided on the way with a control valve V capable of adjusting the pressure of the supply passage 5 according to the supplied current, a suction passage 10 connecting the supply passage 5 and the discharge passage 6, and a middle of the suction passage 10 And a suction check valve 11 for permitting only the flow of fluid from the discharge passage 6 to the supply passage 5, and between the control valve V and the pump 4 in the middle of the supply passage 5 Supply side check valve 12 that allows only fluid flow from the valve to the control valve V side, and control A flow priority valve FPV is provided on the upstream side of the control valve V in the middle of the passage 19 to allow only the passage of the fluid having a flow rate equal to or less than a predetermined flow rate. Is configured.

  Further, in the present embodiment, the fluid pressure circuit FC is provided in the extension side passage 7 to provide resistance to the flow from the extension side chamber R1 to the switching valve 9 and allows the flow in the opposite direction to be extended. A damping element VE, and a compression-side damping element VC which is provided in the compression-side passage 8 and which resists the flow from the pressure-side chamber R2 to the switching valve 9 and allows the flow in the opposite direction is provided.

  Subsequently, each part will be described in detail. The actuator AC of this example includes a rod 3 which is movably inserted into the cylinder 1 and connected to the piston 2. The rod 3 is inserted only into the expansion chamber R1, and the actuator AC is a so-called actuator. The single rod type cylinder device is used. The reservoir R is provided independently of the actuator AC at the position shown in FIG. 1, and although not shown in detail, an outer cylinder disposed on the outer peripheral side of the cylinder 1 in the actuator AC is provided, It may be formed of an annular gap between the cylinder 1 and the outer cylinder.

  When the suspension device S is applied to a vehicle, as shown in FIG. 2, the cylinder 1 is connected to one of the sprung member B and the unsprung member W of the vehicle, and the rod 3 is mounted on the sprung member B and unsprung It may be connected to the other one of the members W and interposed between the sprung member B and the unsprung member W.

  Then, the expansion side chamber R1 and the pressure side chamber R2 are filled with a fluid such as hydraulic oil as a fluid, for example, and the reservoir R is also filled with the liquid and the gas. As the liquid filled in the expansion 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 other than the hydraulic oil. Further, in the present invention, the chamber compressed in the extension stroke is the expansion side chamber R1, and the chamber compressed in the contraction stroke is the pressure side chamber R2.

  The pump 4 of this example is set to a one-way discharge type that sucks in fluid from the suction side and discharges fluid from the discharge side, and is driven by the motor 13. Various types of motors, for example, a brushless motor, an induction motor, a synchronous motor, and the like can be adopted as the motor 13 regardless of direct current or alternating current.

  The suction side of the pump 4 is connected to the reservoir R by the pump passage 14, and the discharge side is connected to the supply passage 5. Therefore, when driven by the motor 13, the pump 4 sucks the fluid from the reservoir R and discharges the fluid to the supply passage 5.

  As shown in FIG. 1, the switching valve 9 in this example is an electromagnetic switching valve with four ports and two positions. The switching valve 9 communicates port A and port P while communicating port B and port T, and communicates pressure between port A and port T and port B and port P. A valve body 9a having a position 9c, a spring 9d for energizing the valve body 9a, and a solenoid 9e for giving a thrust force against the spring 9d to the valve body 9a. When the power is not supplied to the solenoid 9e, the valve body 9a is biased by the spring 9d to take the expansion side supply position 9b, and when the solenoid 9e is energized, the valve body 9a is pushed by the thrust from the solenoid 9e. , And the pressure side supply position 9c.

  The port P of the switching valve 9 is connected to the discharge side of the pump 4 via the supply passage 5, the port T is connected to the reservoir R via the discharge passage 6, and the port A is via the extension passage 7. The port B is connected to the pressure side chamber R 2 via the pressure side passage 8.

  Therefore, when the switching valve 9 takes the extension side supply position 9b, the supply passage 5 is communicated with the extension chamber R1 through the extension passage 7, and the discharge passage 6 is communicated with the pressure chamber R2 through the pressure passage 8. Therefore, when the pump 4 is driven in this state, the fluid is supplied to the expansion side chamber R1 and the fluid is discharged from the pressure side chamber R2 to the reservoir R, so that the actuator AC contracts. On the other hand, when the switching valve 9 takes the pressure side supply position 9c, the supply passage 5 is communicated with the pressure chamber R2 through the pressure passage 8, and the discharge passage 6 is communicated with the extension chamber R1 through the extension passage 7. Therefore, when the pump 4 is driven in this state, the fluid is supplied to the pressure side chamber R2 and the fluid is discharged from the expansion side chamber R1 to the reservoir R, so that the actuator AC extends.

  In addition, as described above, the extension-side damping element VE which resists the flow from the extension-side chamber R1 to the switching valve 9 and allows the flow in the opposite direction is provided in the middle of the extension-side passage 7 It is provided.

  The expansion-side damping element VE only provides the expansion-side damping valve 15 that provides resistance to the flow from the expansion-side chamber R1 toward the switching valve 9, and the flow from the switching valve 9 toward the expansion-side chamber R1 in parallel with the expansion-side damping valve 15. And an expansion side check valve 16 that allows the Thus, for the flow of fluid moving from the expansion chamber R1 toward the switching valve 9, the expansion check valve 16 is maintained in the closed state, so the fluid passes only the expansion damping valve 15 It flows toward the switching valve 9 side. Conversely, for the flow of fluid moving from the switching valve 9 toward the expansion chamber R1, the expansion check valve 16 opens and the expansion check valve 16 resists the flow compared to the expansion damping valve 15 Is smaller, the fluid preferentially flows through the expansion check valve 16 and flows toward the expansion chamber R1. Note that 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 only allows flow from the expansion-side chamber R1 to the switching valve 9 Good.

  Further, as described above, the pressure-side damping element VC is provided in the middle of the pressure-side passage 8 to resist the flow from the pressure-side chamber R2 toward the switching valve 9 and to allow the flow in the opposite direction. ing.

  The compression side damping element VC is provided in parallel with the compression side damping valve 17 that gives resistance to the flow from the pressure side chamber R2 toward the switching valve 9, and parallel to the pressure side damping valve 17 to allow only the flow from the switching valve 9 toward the pressure side chamber R2. The pressure side check valve 18 is provided. Therefore, for the flow of the fluid moving from the pressure side chamber R2 toward the switching valve 9, the pressure side check valve 18 is maintained in the closed state, so the fluid passes only the pressure side damping valve 17 and the switching valve It flows toward the 9 side. On the other hand, for the flow of fluid moving from the switching valve 9 toward the pressure side chamber R2, the pressure side check valve 18 is opened, and the pressure side check valve 18 has less resistance to the flow compared to the pressure side damping valve 17. The fluid preferentially passes through the pressure check valve 18 and flows toward the pressure 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 allows only the flow from the pressure-side chamber R2 toward the switching valve 9 .

  Further, the fluid is discharged from the pump 4 to the supply passage 5, and in order to control the pressure of the supply passage 5, the control valve V is provided in the fluid pressure circuit FC. Specifically, the control valve V is provided in the middle of the control passage 19 connecting the supply passage 5 and the discharge passage 6, and the pressure of the supply passage 5 upstream of the control valve V is adjusted when the valve opening pressure is adjusted. Can be controlled.

  In this example, the control valve V is an electromagnetic pressure control valve, and the valve 20a provided in the middle of the control passage 19 and the pressure on the upstream side which is the supply passage 5 side to the valve 20a are the pilot pressure A pilot passage 20b that causes the body 20a to act in the valve opening direction, and a solenoid 20c that applies a thrust to the valve body 20a. The solenoid 20c is composed of a spring and a coil (not shown). The spring in the solenoid 20c always biases the valve body 20a in the valve opening direction, while the solenoid 20c can generate a thrust against the spring biasing the valve body 20a when energized. There is. Therefore, the valve opening pressure of the control valve V can be adjusted to a high or low level by adjusting the amount of current supplied to the solenoid 20 c, so the pressure in the supply passage 5 can be controlled to the valve opening pressure of the control valve V. As described above, the control valve V can adjust the pressure of the supply passage 5 according to the supply current, but the specific configuration of the control valve V described above is an example and is not limited thereto. .

  Further, in the control valve V of this embodiment, the valve opening pressure proportional to the amount of current supplied to the solenoid 20 c can be obtained, and the valve opening pressure increases as the amount of current increases. When the current is not supplied, the valve opening pressure is minimized. Further, the control valve V has a characteristic in which there is no pressure override in which the pressure loss increases in proportion to the flow rate in the practical area of the suspension device S. In the practical area, for example, when the actuator AC is used by being interposed between the vehicle body B of the vehicle and the wheel W as shown in FIG. And it is sufficient. Moreover, in the practical area, the control valve V has the characteristic that there is no pressure override in which the pressure loss increases in proportion to the flow rate. The flow rate that can pass through the control valve V when the actuator AC expands and contracts within the range of 1 m per second. The control valve V has the characteristic that the pressure override can be ignored. Further, in the present embodiment, the control valve V has a very small valve opening pressure at the time of non-energization, and hardly gives resistance to the flow of fluid passing at the time of non-energization.

  Further, as described above, only the passage of fluid having a predetermined flow rate or less is permitted on the control passage 19 and on the upstream side of the control valve V, and the excess flow rate exceeding the predetermined flow rate is passed through the bypass passage BP. There is provided a flow priority valve FPV which discharges to the reservoir R. The bypass passage BP is connected to the discharge passage 6 connecting the control passage 19 to the reservoir R via the flow priority valve FPV. The bypass path BP may be directly connected to the reservoir R without via the discharge path 6.

  By the way, the predetermined flow rate mentioned here can be arbitrarily set as long as the control valve V is not difficult to control when passing through the control valve V.

  Hereinafter, the flow priority valve FPV will be described in detail. The flow priority valve FPV of this example connects the upstream and downstream of the control passage 19 and has an orifice O for resisting the flow of the passing fluid, as shown in FIG. A return passage 31 branched from the upstream side of O and leading to the reservoir R via the bypass passage BP, a valve seat 41 provided in the middle of the return passage 31, and a valve seat 41 It has a valve body 42 which opens and closes, and a biasing spring SP as a biasing member which biases the valve body 42 toward the valve seat 41.

  Further, the pressure on the upstream side of the control passage 19 acts on the valve body 42 in the direction of opening the valve body 42 and the pressure on the downstream side of the control passage 19 acts on the valve body 42 in the direction of closing the valve body 42. ing.

  According to the above configuration, when the fluid flows into the control passage 19, the fluid passes through the control passage 30 and passes through the control valve V, but at this time, a pressure loss due to the orifice O occurs. Then, since the pressure on the upstream side is higher than that on the downstream side, a difference occurs between the pressure on the upstream side of the flow priority valve FPV in the control passage 19 and the pressure on the downstream side of the flow priority valve FPV.

  Further, in this example, when the valve body 42 is seated on the valve seat 41, the pressure receiving area of the pressure on the upstream side of the control passage 19 in the valve body 42 and the pressure receiving area of the pressure on the downstream side of the control passage 19 Are set to be equal.

  Here, the force for pushing the valve body 42 in the valve opening direction is determined by the product of the pressure on the upstream side of the control passage 19 and the pressure receiving area receiving the pressure, and the force for pushing the valve body 42 in the valve closing direction is It is determined by the product of the biasing force of the biasing spring SP, the pressure on the downstream side of the control passage 19, and the pressure receiving area for receiving the pressure.

  Therefore, the force pushing the valve body 42 in the valve opening direction by the pressure on the upstream side exceeds the pushing force in the direction to close the valve body 42 by the pressure on the downstream side and exceeds the biasing force of the biasing spring SP. The valve body 42 separates from the valve seat 41 and opens the return passage 31. Thus, when the flow rate of the fluid flowing into the control passage 19 exceeds the predetermined flow rate, the biasing force of the biasing spring SP is set to be smaller than the force pressing the valve body 42 in the valve opening direction. The excess flow rate exceeding the flow rate is discharged to the reservoir R via the return passage 31 and the bypass passage BP. Therefore, only the fluid having a predetermined flow rate or less flows through the control valve V disposed downstream of the flow priority valve FPV.

  Further, by adjusting the biasing force of the biasing spring SP, the pressing force in the direction to close the valve body 42 can be adjusted, so that the flow rate flowing to the control valve V disposed downstream of the flow priority valve FPV can be determined. .

  Subsequently, a specific example of the flow priority valve FPV described above will be described based on FIG. The flow priority valve FPV of this example includes a bottomed cylindrical housing 40, an annular valve seat member 43 provided on an inner peripheral portion of the housing 40, a valve body 42 that is seated on the valve seat member 43, and a valve A biasing spring SP as a biasing member that biases the body 42 toward the valve seat member 43 is provided.

  The housing 40 of the present example is formed in a bottomed cylindrical shape, including a cylindrical portion 40 a and a bottom portion 40 b closing an opening on one end side of the cylindrical portion 40 a. The cylindrical portion 40a of this example has a small diameter portion 40c formed on the bottom 40b side and a large diameter portion 40d formed on the opposite bottom side and having a larger inside diameter than the small diameter portion 40c. A stepped portion 40e is formed between the portion 40c and the large diameter portion 40d.

  Further, a communication port 40g connected to the downstream side of the control passage 19 is provided at the bottom 40b of the housing 40. Further, the opening 40 f of the housing 40 is connected to the upstream side of the control passage 19. The cylindrical portion 40 a of the housing 40 is provided with a discharge port 40 h connected to the bypass path BP.

  Further, the valve seat member 43 vertically rises from the inner peripheral end of the flange portion 43a toward the bottom portion 40b side, with the annular flange portion 43a fixed on the upstream side of the discharge port 40h of the large diameter portion 40d. It has an annular seat 43b which functions as the valve seat 41 of FIG. 3 and on which the valve body 42 is seated.

  The valve seat member 43 may be formed integrally with the housing 40. However, as in this example, when provided separately from the housing 40, the valve body of the flow priority valve FPV is assembled to the housing 40. After mounting 42, the valve seat member 43 can be fixed. Therefore, if the valve seat member 43 is separated from the housing 40 as in this example, it is advantageous for the assembling operation of the flow priority valve FPV. The method for fixing the valve seat member 43 to the housing 40 is not particularly limited, and for example, it may be fixed by caulking or screwing.

  The valve body 42 is provided so as to stand up from the disc-like valve head 42a that is seated on and seated on the seat portion 43b of the valve seat member 43 and the side of the valve seat of the valve head 42a. And a cylindrical sliding portion 42b which is freely inserted. Further, the valve head 42a is formed with an orifice O which connects the upstream side and the downstream side of the control passage 19 and which resists the flow of the passing fluid.

  Further, between the valve head 42a of the valve body 42 and the bottom portion 40b of the housing 40, a biasing spring SP is provided as a biasing member for biasing the valve body 42 toward the seat portion 43b of the valve seat member 43. It is done. Thus, the valve body 42 is biased by the biasing spring SP and is seated on the seat portion 43 b of the valve seat member 43. The biasing member is not limited to a spring, and may be an elastic body such as rubber.

  And, in the embodiment of FIG. 4, the restricted passage 30 is constituted by the opening 40f of the housing 40, the orifice O and the communication port 40g, and the return passage 31 is constituted by the opening 40f of the housing 40 and the discharge port 40h. It is configured.

  Further, in the present embodiment, the pressure receiving area for receiving pressure on the upstream side of the control passage 19 in the valve body 42 is an area of a circle whose outer diameter is the inner diameter D1 of the seat portion 43b in contact with the valve head 42a of the valve body 42 It becomes the area except the area of the circle which makes the diameter of O an outside diameter. On the other hand, the pressure receiving area of the valve body 42 receiving the pressure on the downstream side of the control passage 19 is the area of a circle whose outer diameter is the inner diameter D2 of the small diameter portion 40c of the housing 40, and the area of the circle whose outer diameter is the orifice O Is the area excluding

  The inner diameter D1 of the seat portion 43b of the valve seat member 43 and the inner diameter D2 of the small diameter portion 40c of the housing 40 are set equal. Therefore, in this example, when the valve body 42 is seated on the seat portion 43 b of the valve seat member 43, the pressure receiving area of the valve body 42 receiving the pressure on the upstream side of the control passage 19 and the downstream side of the control passage 19 The pressure receiving area for receiving pressure is equal.

  Further, the operation of the flow priority valve FPV of this example will be described. First, the case where the flow rate of the fluid flowing into the control passage 19 is equal to or less than the predetermined flow rate will be described. The fluid flowing into the control passage 19 flows to the downstream side provided with the control valve V through the restriction passage 30 constituted by the opening 40f of the housing 40, the orifice O, and the communication port 40g.

  At this time, since the orifice O causes a pressure loss in the fluid flow, the pressure on the upstream side of the control passage 19 becomes higher than the pressure on the downstream side of the control passage 19. However, the biasing force of the biasing spring SP is set to be larger than the pressing force in the direction to open the valve body 42 when the flow rate of the fluid flowing into the control passage 19 is less than the predetermined flow rate. Therefore, when the flow rate of the fluid flowing in from the upstream side is equal to or less than the predetermined flow rate, the valve body 42 does not separate from the seat portion 43b of the valve seat member 43, and all the fluid flowing in from the upstream side is provided downstream. Flows to the control valve V.

  Therefore, in the graph shown in FIG. 5 in which the flow rate through the communication port 40g and the discharge port 40h is taken on the vertical axis and the flow rate through the opening 40f on the housing 40 is taken along the horizontal axis, The flow characteristic of the flow priority valve FPV in the case where the amount of fluid flowing in is less than or equal to the predetermined flow rate is the characteristic shown by (1) in FIG.

  In contrast, when the flow rate of the fluid flowing in from the upstream side of the control passage 19 exceeds the predetermined flow rate, the pressure loss that occurs when the fluid flowing in from the upstream side through the opening 40f of the housing 40 passes through the orifice O is The pressure on the upstream side also increases according to the inflow since the flow rate is larger than the case where the flow rate is less than or equal to the predetermined flow rate. At this time, the biasing force of the biasing spring SP is set to be smaller than the pressing force in the direction of opening the valve body 42 when the flow rate of the fluid flowing into the control passage 19 exceeds a predetermined flow rate. Therefore, when the flow rate of the fluid flowing in from the upstream side of the control passage 19 exceeds the predetermined flow rate, the force pushing the valve body 42 in the valve opening direction overcomes the biasing force of the biasing spring SP and The seat portion 43 b of the seat member 43 is separated.

  At this time, the size of the gap generated between the valve body 42 and the seat portion 43 b of the valve seat member 43 changes in accordance with the flow rate of the fluid flowing in from the upstream side of the control passage 19. Therefore, the excess flow rate exceeding the predetermined flow rate is discharged to the bypass path BP through the discharge port 40 h through the gap generated between the valve body 42 and the seat portion 43 b of the valve seat member 43. Therefore, as shown in (2) in FIG. 5, the flow rate flowing through the communication port 40g becomes constant regardless of how much the flow rate of the fluid flowing in from the upstream side of the control passage 19 increases. Since the increase in the flow rate of the fluid flowing in from the upstream side of the control passage 19 is all discharged into the bypass passage BP through the discharge port 40h, the flow rate through the discharge port 40h when the inflowing fluid exceeds the predetermined flow rate. The flow rate characteristic of the discharged fluid is the characteristic shown by (3) in FIG.

  However, the specific example of the above-mentioned flow priority valve FPV is an example, and it is not limited to this.

  Returning to the control passage 19, a suction passage 10 connecting the supply passage 5 and the discharge passage 6 is provided in parallel. In the middle of the suction passage 10, there is provided a suction check valve 11 which permits only the flow of fluid from the discharge passage 6 to the supply passage 5, and the suction passage 10 is provided with fluid flowing from the discharge passage 6 to the supply passage 5. It is set in a one-way passage that allows only flow.

  A supply side check valve 12 is provided between the control valve V and the pump 4 in the middle of the supply passage 5. More specifically, the supply-side check valve 12 is provided on the pump 4 side in the middle of the supply passage 5 and at the pump 4 side of the connection point between the control passage 19 and the suction passage 10. Only the flow from the valve to the control valve V side is permitted, and the opposite flow is blocked. Therefore, even if the pressure on the switching valve 9 side is higher than the discharge pressure of the pump 4, the backflow of the fluid to the pump 4 side is prevented by closing the supply side check valve 12.

  The suspension device S is configured as described above, and subsequently, its operation will be described. First, an operation at a normal time when the motor 13, the pump 4, the switching valve 9, and the control valve V can be operated normally will be described.

  Basically, the pump 4 is driven by the motor 13 and the fluid discharged by the pump 4 is supplied to the chamber connected to the pump 4 of the expansion side chamber R1 and the pressure side chamber R2 by the switching valve 9 while the other The chamber is in communication with the reservoir R. Thus, the actuator AC can be actively extended or contracted. When the thrust force generated by the actuator AC is in the extension direction of the actuator AC, the switching valve 9 is set as 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. Conversely, when the thrust force generated by the actuator AC is in the contraction direction of the actuator AC, the extension valve R1 is connected to the supply passage 5 and the pressure chamber R2 is connected to the reservoir R, with the switching valve 9 as the expansion side supply position 9b. Do. Then, by adjusting the pressure of the supply passage 5 by the control valve V, it is possible to control the magnitude of the thrust in the extension direction or the contraction direction of the actuator AC.

  In controlling the thrust, for example, as shown in FIG. 2, information capable of grasping the vibration condition of the vehicle necessary for a control law suitable for vibration suppression of the vehicle, for example, the vertical direction of the sprung member B and the unsprung member W Obtain vehicle information such as information on acceleration and velocity and information on expansion and contraction velocity and expansion and contraction acceleration of actuator AC, obtain the target thrust to be generated by actuator AC according to the above control law, and determine the thrust of actuator AC according to the target thrust A controller C for determining the amount of current to be supplied to the control valve V necessary to generate the current, the selection of the expansion side supply position 9b and the pressure side supply position 9c in the switching valve 9, and the amount of current to be supplied to the motor 13 driving the pump 4; In response to a command from controller C, control valve V, switching valve 9 and motor 13 are The may be provided with driver devices Dr supplies. The driver device Dr includes, for example, a drive circuit for PWM driving the solenoid 20c and the solenoid 9e in the control valve V and the switching valve 9, and a drive circuit for PWM driving the motor 13. The current is supplied to the solenoid 20c, the solenoid 9e and the motor 13 as determined by the controller C. In addition, each drive circuit in driver device Dr may be drive circuits other than the drive circuit which performs PWM drive. Then, the controller C may select the pressure-side supply position 9 c for the switching valve 9 in the direction in which the target thrust force generated by the actuator AC is in the extension direction of the actuator AC. In this way, in the contraction direction of the actuator AC, the controller C selects the expansion side supply position 9 b for the switching valve 9 in the contraction direction of the actuator AC, and the driver device Dr selects the switching valve 9 as described above. The current is supplied to or shut off from the solenoid 9e to switch to the selected position. Specifically, in the present embodiment, when the actuator AC is caused to contract, in order to supply the fluid to the expansion chamber R1 and discharge the fluid from the pressure chamber R2 to the reservoir R, the expansion supply position 9b is taken. The current is not supplied to the solenoid 9e in the switching valve 9, and the current is not supplied. Conversely, when the actuator AC is operated to extend, the solenoid 9e in the switching valve 9 is set to take the pressure side supply position 9c in order to supply the fluid to the pressure side chamber R2 and discharge the fluid from the expansion side chamber R1 to the reservoir R. It suffices to supply current. As a control law used for controlling the thrust in the suspension device S, a control law suitable for a vehicle may be selected, and for example, it is preferable to adopt a control law which is excellent in suppression of vehicle vibration such as skyhook control. Further, in this case, although the controller C and the driver device Dr are described separately, the suspension device S may be controlled by one controller having the functions of the controller C and the driver device Dr. The information input to the controller C may be any information suitable for the control rule adopted by the controller C, and although not shown, the information may be detected by a sensor or the like and input to the controller C.

  The operation in the case of positively expanding and contracting the actuator AC has been described above. However, during traveling of the vehicle, the actuator AC expands and contracts due to the unevenness of the road surface. The operation based on the points to be

  First, an operation in a state where the pump 4 is driven to discharge the fluid to the supply path 5 will be described. When the actuator AC expands and contracts due to a disturbance, four cases can be considered in the case of dividing the direction in which the actuator AC generates thrust and the expansion and contraction direction of the actuator AC.

  First, a case where the suspension device S is caused to exert a thrust that pushes the piston 2 downward and a case where the actuator AC is extended due to an external force will be described. Since the direction of the thrust generated by the actuator AC is the direction in which the piston 2 is pushed downward, it is necessary to supply the fluid to the expansion chamber R1. Therefore, the switching valve 9 is switched to take the expansion side supply position 9 b to connect the expansion side chamber R 1 to the supply path 5 and communicate the pressure side chamber R 2 to the reservoir R through the discharge path 6.

  Since the volume of the expansion side chamber R1 decreases when the actuator AC is operated for expansion, the reduced amount of fluid is discharged from the expansion side chamber R1 through the expansion side damping valve 15, and the control valve V is further supplied via the supply passage 5. Flow to reservoir R. In addition, since the supply side check valve 12 is provided, even if the pressure of the supply passage 5 dynamically becomes higher than the discharge pressure of the pump 4, the fluid does not flow back to the pump 4 side. On the other hand, the fluid corresponding to the volume expansion is supplied from the reservoir R via the discharge passage 6 to the pressure side chamber R2 whose volume is increased.

  Since the pressure in the supply passage 5 is controlled by the control valve V to the opening pressure of the control valve V, the pressure in the expansion side chamber R1 is such that the fluid discharged from the expansion side chamber R1 passes through the expansion side damping valve 15 The pressure loss that occurs during the operation is higher than the pressure in the supply passage 5. Therefore, the expansion side chamber R1 in this case is higher than the pressure of the reservoir R by a pressure in which the pressure loss by the expansion side damping valve 15 is superimposed on the valve opening pressure of the control valve V. Therefore, the thrust of the actuator AC takes the pressure receiving area of the piston 2 and the pressure of the extension side chamber R1 with the area facing the extension side chamber R1 of the piston 2 (area obtained by subtracting the cross sectional area of the rod 3 from the area of the piston 2) It is the product of Therefore, in the graph shown in FIG. 6 in which the direction of thrust of the actuator AC is taken on the vertical axis and the expansion / contraction speed of the actuator AC is taken on the horizontal axis, the thrust of the actuator AC when the valve opening pressure of the control valve V is maximized. Becomes the characteristic shown by line (1) in FIG. In this case, a force that is the product of the pressure of the pressure side chamber R2 and the pressure receiving area facing the pressure side chamber R2 of the piston 2 is generated as a thrust that pushes up the piston 2. However, since the pressure side chamber R2 has the same pressure as the reservoir R, and the pressure of the extension side chamber R1 is captured as a pressure difference with the pressure of the reservoir R, the thrust that pushes up the piston 2 can be regarded as zero.

  Further, as described above, in the case where the suspension device S is caused to exert a thrust that pushes the piston 2 downward and the actuator AC is operated to extend by an external force, the fluid discharged from the expansion side chamber R1 and the pump 4 Any fluid discharged from the fluid passes through the control passage 19. That is, in this case, a large flow of fluid, which is the sum of the flow rate of the fluid discharged from the expansion chamber R1 and the flow rate of the fluid discharged from the pump 4, flows into the control passage 19. However, in the present embodiment, since the flow priority valve FPV is provided upstream of the control valve V of the control passage 19, the excess flow amount exceeding the predetermined flow rate set in the flow priority valve FPV is the bypass passage BP. And is discharged to the reservoir R through the discharge passage 6. Therefore, only a predetermined flow of fluid flows through the control valve V.

  Subsequently, a case where the suspension device S is caused to exert a thrust that pushes the piston 2 downward and a case where the actuator AC is contracted due to an external force will be described. Since the direction of the thrust generated by the actuator AC is the direction in which the piston 2 is pushed downward, it is necessary to supply the fluid to the expansion chamber R1. Also in this case, the switching valve 9 is switched to take the expansion side supply position 9 b to connect the expansion side chamber R 1 to the supply path 5 and connect the pressure side chamber R 2 to the reservoir R through the discharge path 6.

  When the actuator AC is contracting, the volume of the expansion chamber R1 increases, and the flow required for the expansion chamber R1 when the discharge flow rate of the pump 4 is equal to or more than the volume increase of the expansion chamber R1 per unit time. The discharge flow rate of the pump 4 is further increased. Therefore, the fluid discharged from the pump 4 flows into the expansion chamber R1 through the expansion check valve 16, and the remaining fluid not absorbed in the expansion chamber R1 of the discharge flow rate of the pump 4 is stored in the reservoir R through the control valve V. Flow to Therefore, the pressure of the expansion side chamber R1 becomes equal to the pressure of the supply passage 5, and the valve opening pressure of the control valve V is controlled. In the pressure side chamber R2 in which the other volume decreases, the fluid for the volume reduction is discharged to the reservoir R from the pressure side chamber R2 via the pressure side damping valve 17 and the discharge passage 6. The pressure in the pressure side chamber R2 is higher than the pressure in the reservoir R by the pressure loss generated when the fluid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17. Therefore, in such a situation, the pressure in the expansion chamber R1 is equal to the valve opening pressure of the control valve V, but the pressure in the pressure chamber R2 is higher than the pressure in the reservoir R by the pressure loss by the pressure damping valve 17. As the flow rate discharged from the pressure side chamber R2 increases, the pressure loss also increases. Therefore, the thrust of the actuator AC is a force obtained by subtracting the product of the pressure in the pressure chamber R2 and the pressure receiving area in the pressure chamber R2 of the piston 2 from the product of the pressure in the expansion chamber R1 and the pressure receiving area of the piston 2 Become. Here, as the flow rate discharged from the pressure side chamber R2 increases, the pressure loss also increases, and the thrust of the actuator AC decreases. From the above, in the case where the suspension device S is caused to exert a thrust that pushes the piston 2 downward and the actuator AC is contracted by an external force, the discharge flow rate of the pump 4 is the volume of the expansion side chamber R1 per unit time. The thrust of the actuator AC when the valve opening pressure of the control valve V is maximized when the amount is equal to or more than the increase amount has a characteristic shown by a line (2) in FIG.

  On the other hand, when the contraction speed of the actuator AC is high and the discharge flow rate of the pump 4 is less than the volume increase of the expansion chamber R1 per unit time, the fluid supply from the pump 4 is the volume per unit time of the expansion chamber R1. It can not catch up with the amount of increase, and all the fluid discharged from the pump 4 is absorbed by the expansion side chamber R1. Then, the fluid does not flow to the control valve V, and the fluid of an insufficient amount in the expansion side chamber R1 is supplied from the reservoir R through the discharge passage 6 and the suction passage 10 with the suction check valve 11 opened. In such a situation, the pressure in the expansion chamber R1 is substantially equal to the pressure in the reservoir R, but the pressure in the compression chamber R2 is higher than the pressure in the reservoir R by the pressure loss due to the pressure damping valve 17. Therefore, the actuator AC can not exert a thrust in the direction of pushing the piston 2 downward, and exerts a thrust in the opposite direction, that is, a direction of pushing the piston 2 upward. From the above, in the case where the suspension device S is caused to exert a thrust that pushes the piston 2 downward and the actuator AC is contracting by the external force, the discharge flow rate of the pump 4 is the unit time of the expansion side chamber R1. If it is less than the increase in the volume of the hit, the thrust can not be exerted in the direction of pushing the piston 2 downward. Therefore, regardless of the valve opening pressure of the control valve V, the thrust of the actuator AC has the characteristic shown by the line (3) in FIG. Therefore, when the valve opening pressure of the control valve V is maximized, the characteristic of line (2) in FIG. 6 is obtained when the discharge flow rate of the pump 4 is equal to or greater than the volume increase per unit time of the expansion chamber R1. When the flow rate is less than the volume increase per unit time of the expansion side chamber R1, the characteristic changes to the characteristic of the line (3) in FIG.

  Next, a case where the suspension device S is caused to exert a thrust that pushes up the piston 2 upward, and the case where the actuator AC is contracting due to an external force will be described. The direction of the thrust generated by the actuator AC is the direction in which the piston 2 is pushed upward, and it is necessary to supply the fluid to the pressure side chamber R2. Therefore, the switching valve 9 is switched so as to adopt the pressure side supply position 9c, and the pressure side chamber R2 is connected to the supply passage 5, and the extension side chamber R1 is communicated with the reservoir R through the discharge passage 6.

  When the actuator AC is contracting, the volume of the pressure side chamber R2 is reduced, so the amount of the reduced fluid is discharged from the pressure side chamber R2 through the pressure side damping valve 17, and the control valve V is further It passes to the reservoir R. In addition, since the supply side check valve 12 is provided, even if the pressure of the supply passage 5 dynamically becomes higher than the discharge pressure of the pump 4, the fluid does not flow back to the pump 4 side. On the other hand, the expansion side chamber R1 whose volume is increased is supplied with the fluid corresponding to the volume expansion from the reservoir R via the discharge passage 6.

  The pressure in the supply passage 5 is controlled by the control valve V to the valve opening pressure of the control valve V. Therefore, when the fluid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17, the pressure in the pressure side chamber R2 is controlled. The pressure loss that occurs in the pressure supply line 5 is higher than the pressure in the supply line 5 by the amount of pressure loss that occurs. Accordingly, the pressure side chamber R2 in this case is higher than the pressure of the reservoir R by a pressure in which the pressure loss due to the pressure side damping valve 17 is superimposed on the valve opening pressure of the control valve V. Therefore, the thrust of the actuator AC is the product of the pressure receiving area of the piston 2 and the pressure of the pressure chamber R2, where the area (area of the piston 2) facing the pressure chamber R2 of the piston 2 is a pressure receiving area. Therefore, in the graph shown in FIG. 6, the thrust of the actuator AC when the valve opening pressure of the control valve V is maximized has the characteristic shown by the line (4) in FIG. In this case, a force which is the product of the pressure of the expansion chamber R1 and the pressure receiving area of the expansion chamber R1 of the piston 2 is generated as a thrust that pushes the piston 2 down. However, since the expansion side chamber R1 has the same pressure as the reservoir R, and the pressure of the pressure side chamber R2 is captured as a differential pressure with the pressure of the reservoir R, the thrust that pushes down the piston 2 can be regarded as zero.

  Further, as described above, in the case where the suspension device S is caused to exert a thrust that pushes the piston 2 upward, and the actuator AC is contracted by an external force, the fluid discharged from the pressure side chamber R2 and the pump 4 Any fluid discharged from the fluid passes through the control passage 19. That is, in this case, a large flow of fluid, which is the sum of the flow rate of the fluid discharged from the pressure side chamber R2 and the flow rate of the fluid discharged from the pump 4, flows into the control passage 19. However, in the present embodiment, since the flow priority valve FPV is provided upstream of the control valve V of the control passage 19, the excess flow amount exceeding the predetermined flow rate set in the flow priority valve FPV is the bypass passage BP. And is discharged to the reservoir R through the discharge passage 6. Therefore, only a predetermined flow of fluid flows through the control valve V.

  Furthermore, a case where the suspension device S is caused to exert a thrust that pushes the piston 2 upward, and a case where the actuator AC is operated to extend by an external force will be described. Since the direction of the thrust generated by the actuator AC is the direction in which the piston 2 is pushed upward, it is necessary to supply the fluid to the pressure side chamber R2. Therefore, in this case, the switching valve 9 is switched so as to adopt the pressure side supply position 9c, and the pressure side chamber R2 is connected to the supply passage 5, and the extension side chamber R1 is communicated with the reservoir R through the discharge passage 6.

  When the actuator AC is operated for extension, the volume of the pressure side chamber R2 increases, but if the discharge flow rate of the pump 4 is equal to or more than the volume increase per unit time of the pressure side chamber R2, the pressure side chamber R2 is required. The discharge flow rate of the pump 4 is larger than the flow rate. Therefore, the fluid discharged from the pump 4 flows into the pressure chamber R2 through the pressure check valve 18, and the remaining fluid not absorbed in the pressure chamber R2 of the discharge flow rate of the pump 4 flows to the reservoir R through the control valve V. Flow. Therefore, the pressure of the pressure side chamber R2 becomes equal to the pressure of the supply passage 5, and the valve opening pressure of the control valve V is controlled. In the expansion side chamber R1 in which the volume of the other decreases, fluid of a volume reduction amount is discharged to the reservoir R from the expansion side chamber R1 via the expansion side damping valve 15 and the discharge passage 6. The pressure in the expansion chamber R1 is higher than the pressure in the reservoir R by the pressure loss generated when the fluid discharged from the expansion chamber R1 passes through the expansion damping valve 15. Therefore, in such a situation, the pressure in pressure side chamber R2 becomes equal to the valve opening pressure of control valve V, but the pressure in expansion side chamber R1 becomes higher than the pressure in reservoir R by the pressure loss by expansion side damping valve 15. The larger the flow rate discharged from the expansion chamber R1, the larger the pressure loss. Therefore, the thrust of the actuator AC is a force obtained by subtracting the product of the pressure in the expansion chamber R1 and the pressure receiving area in the expansion chamber R1 of the piston 2 from the product of the pressure in the pressure chamber R2 and the pressure receiving area of the piston 2 Become. Here, as the flow rate discharged from the expansion side chamber R1 increases, the pressure loss also increases, and the thrust of the actuator AC decreases. From the above, in the case where the suspension device S is caused to exert a thrust that pushes up the piston 2 upward and the actuator AC is operated to extend by an external force, the discharge flow rate of the pump 4 is the volume per unit time of the pressure side chamber R2. The thrust of the actuator AC when the valve opening pressure of the control valve V is maximized if the amount is equal to or more than the amount of increase has a characteristic shown by line (5) in FIG.

  On the other hand, when the extension speed of the actuator AC is high and the discharge flow rate of the pump 4 is less than the volume increase per unit time of the pressure side chamber R2, the fluid supply from the pump 4 is the volume per unit time of the pressure side chamber R2. It can not catch up with the amount of increase, and all the fluid discharged from the pump 4 is absorbed by the pressure side chamber R2. Then, the fluid does not flow to the control valve V, and the fluid of the insufficient amount in the pressure side chamber R2 is supplied from the reservoir R through the discharge passage 6 and the suction passage 10 with the suction check valve 11 opened. In such a situation, the pressure in the pressure side chamber R2 becomes substantially equal to the pressure in the reservoir R, but the pressure in the expansion side chamber R1 becomes higher than the pressure in the reservoir R by the pressure loss by the expansion side damping valve 15. Therefore, the actuator AC can not exert a thrust in the direction of pushing the piston 2 upward, and exerts a thrust in the opposite direction, that is, a direction of pushing the piston 2 downward. From the above, in the case where the suspension device S is caused to exert a thrust that pushes up the piston 2 upward and the actuator AC is operated to extend by an external force, the discharge flow rate of the pump 4 is the unit time of the pressure side chamber R2. If it is less than the increase in volume of the hit, the thrust can not be exerted in the direction of pushing up the piston 2. Therefore, regardless of the valve opening pressure of the control valve V, the thrust of the actuator AC has the characteristic shown by the line (6) in FIG. Therefore, when the valve opening pressure of the control valve V is maximized, the characteristic of line (5) in FIG. 6 is obtained when the discharge flow rate of the pump 4 is equal to or greater than the volume increase per unit time of the pressure side chamber R2. When the flow rate is less than the volume increase per unit time of the pressure side chamber R2, it changes to the characteristic of the line (6) in FIG.

  The actuator AC exhibits a characteristic that the thrust changes from the line (2) to the line (3) on the contraction side, and the thrust changes from the line (5) to the line (6) on the expansion side Although the characteristics are shown, the change of the characteristics occurs almost instantaneously, and the influence on the ride quality is minor.

  From the above, if the valve opening pressure of control valve V is adjusted, the range from the line connecting line (1) to line (3) to the connected line from line (4) to line (6) in FIG. The thrust of the actuator AC can be made variable in the range of When the pump 4 is driven to supply the discharge flow rate of the pump 4 to the expansion side of the expansion side chamber R1 and the pressure side chamber R2, the discharge flow rate of the pump 4 is larger than the volume increase of the expansion chamber. Then, the thrust can be exerted in the same direction as the expansion and contraction direction of the actuator AC.

  Subsequently, the operation of the suspension device S when the pump 4 is stopped without driving will be described. Also in this case, four cases can be considered in the case where the direction in which the actuator AC receives a disturbance and expands and contracts, and the direction in which the actuator AC generates a thrust are classified.

  First, a case where the suspension device S is caused to exert a thrust that pushes the piston 2 downward and a case where the actuator AC is extended due to an external force will be described. Since the direction of the thrust generated in the actuator AC is the direction to push down the piston 2, the switching valve 9 is switched so as to adopt the expansion side supply position 9 b to connect the expansion side chamber R1 to the supply path 5 and discharge The pressure side chamber R2 is communicated with the reservoir R through the passage 6.

  Since the volume of the expansion chamber R1 decreases when the actuator AC is operated for expansion, the reduced fluid is discharged from the expansion chamber R1 through the expansion damping valve 15 and passes through the control valve V through the supply passage 5. Flow to the reservoir R. In addition, since the supply side check valve 12 is provided, the fluid does not flow to the pump 4 side. On the other hand, the fluid corresponding to the volume expansion is supplied from the reservoir R via the discharge passage 6 to the pressure side chamber R2 whose volume is increased.

  Since the pressure in the supply passage 5 is controlled by the control valve V to the opening pressure of the control valve V, the pressure in the expansion side chamber R1 is such that the fluid discharged from the expansion side chamber R1 passes through the expansion side damping valve 15 The pressure loss that occurs during the operation is higher than the pressure in the supply passage 5. Therefore, the expansion side chamber R1 in this case is higher than the pressure of the reservoir R by the pressure in which the pressure loss by the expansion side damping valve 15 is superimposed on the valve opening pressure of the control valve V. The product of the pressure receiving area of the expansion side chamber R1 and the pressure of the expansion side chamber R1. Therefore, in the graph shown in FIG. 7 in which the direction of thrust of the actuator AC is taken on the vertical axis and the expansion / contraction speed of the actuator AC is taken on the horizontal axis, the thrust of the actuator AC when the valve opening pressure of the control valve V is maximized. Is the characteristic shown by line (7) in FIG. Therefore, if the valve opening pressure of the control valve V is adjusted, the thrust of the actuator AC can be made variable in the range from the line (10) to the line (7) described later in the first quadrant in FIG.

  In this case, a force that is the product of the pressure of the pressure side chamber R2 and the pressure receiving area facing the pressure side chamber R2 of the piston 2 is generated as a thrust that pushes up the piston 2. However, since the pressure side chamber R2 has the same pressure as the reservoir R, and the pressure of the extension side chamber R1 is captured as a pressure difference with the pressure of the reservoir R, the thrust that pushes up the piston 2 can be regarded as zero.

  Subsequently, a case where the suspension device S is caused to exert a thrust that pushes the piston 2 downward and a case where the actuator AC is contracted due to an external force will be described. Although the pump 4 is at rest and no fluid is supplied from the pump 4, the direction of the thrust force generated by the actuator AC is the direction to push the piston 2 downward, so the switching valve 9 is set to take the expansion side supply position 9b. Switch. Thus, the expansion side chamber R1 is connected to the supply path 5, and the pressure side chamber R2 is in communication with the reservoir R through the discharge path 6.

  When the actuator AC is contracting, the volume of the expansion side chamber R1 increases, but no fluid flows in the control valve V because the pump 4 does not discharge fluid. Therefore, the suction check valve 11 is opened and the insufficient amount of fluid in the expansion side chamber R1 is supplied from the reservoir R through the discharge passage 6 and the suction passage 10. In this situation, the pressure in the expansion chamber R1 is approximately equal to the pressure in the reservoir R. In the pressure side chamber R2 in which the other volume is reduced, fluid of a volume reduction amount is discharged to the reservoir R from the pressure side chamber R2 via the pressure side damping valve 17 and the discharge passage 6. The pressure in the pressure side chamber R2 is higher than the pressure in the reservoir R by the pressure loss generated when the fluid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17. Therefore, the actuator AC can not exert a thrust in the direction of pushing the piston 2 downward, and exerts a thrust in the opposite direction, that is, a direction of pushing the piston 2 upward. From the above, in the case where the suspension device S is caused to exert a thrust that pushes down the piston 2 downward, the actuator 2 is contracted due to an external force, and when the pump 4 is stopped, the piston 2 is The thrust can not be exerted in the downward direction. Therefore, regardless of the valve opening pressure of the control valve V, the thrust of the actuator AC has the characteristic shown by the line (8) in FIG. This has the same effect as controlling the compression side damping force to the lowest damping force in the damping force variable damper.

  Next, a case where the suspension device S is caused to exert a thrust that pushes up the piston 2 upward, and the case where the actuator AC is contracting due to an external force will be described. Since the direction of the thrust force generated in the actuator AC is a direction to push up the piston 2, the switching valve 9 is switched so as to adopt the pressure side supply position 9 c to connect the pressure side chamber R2 to the supply path 5 and The expansion chamber R1 is made to communicate with the reservoir R through 6.

  When the actuator AC is contracting, the volume of the pressure side chamber R2 decreases, so the fluid for the reduction is discharged from the pressure side chamber R2 through the pressure side damping valve 17 and passes through the control valve V through the supply passage 5. Flow to the reservoir R. In addition, since the supply side check valve 12 is provided, the fluid does not flow to the pump 4 side. On the other hand, the expansion side chamber R1 whose volume is increased is supplied with the fluid corresponding to the volume expansion from the reservoir R via the discharge passage 6.

  The pressure in the supply passage 5 is controlled by the control valve V to the valve opening pressure of the control valve V. Therefore, when the fluid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17, the pressure in the pressure side chamber R2 is controlled. The pressure loss that occurs in the pressure supply line 5 is higher than the pressure in the supply line 5 by the amount of pressure loss that occurs. Therefore, the pressure side chamber R2 in this case is higher than the pressure of the reservoir R by the pressure in which the pressure loss due to the pressure side damping valve 17 is superimposed on the valve opening pressure of the control valve V. It is the product of the pressure receiving area of the pressure side chamber R2 and the pressure of the pressure side chamber R2. Therefore, in the graph shown in FIG. 7, the thrust of the actuator AC when the valve opening pressure of the control valve V is maximized has the characteristic shown by the line (9) in FIG. Therefore, by adjusting the valve opening pressure of the control valve V, the thrust of the actuator AC can be made variable in the range from the line (8) to the line (9) in the third quadrant in FIG. In this case, a force that is the product of the pressure of the expansion chamber R1 and the pressure receiving area facing the expansion chamber R1 of the piston 2 is generated as a thrust that pushes the piston 2 down. However, since the expansion side chamber R1 has the same pressure as the reservoir R, and the pressure of the pressure side chamber R2 is captured as a differential pressure with the pressure of the reservoir R, the thrust that pushes down the piston 2 can be regarded as zero.

  Subsequently, a case where the suspension device S is caused to exert a thrust that pushes the piston 2 upward, and a case where the actuator AC is operated to extend by an external force will be described. The pump 4 is stopped and no fluid is supplied from the pump 4, but the direction of the thrust force generated by the actuator AC is the direction to push the piston 2 upward, so the switching valve 9 is set to take the pressure side supply position 9c. Switch. Thus, the pressure side chamber R2 is connected to the supply passage 5, and the expansion side chamber R1 is in communication with the reservoir R through the discharge passage 6.

  When the actuator AC is in the extension operation, the volume of the pressure side chamber R2 increases, but no fluid flows in the control valve V because the pump 4 does not discharge the fluid. Therefore, the suction check valve 11 is opened and the insufficient amount of fluid in the pressure side chamber R2 is supplied from the reservoir R through the discharge passage 6 and the suction passage 10. In this situation, the pressure in the pressure chamber R2 is approximately equal to the pressure in the reservoir R. In the expansion side chamber R1 in which the volume of the other decreases, fluid of a volume reduction amount is discharged to the reservoir R from the expansion side chamber R1 via the expansion side damping valve 15 and the discharge passage 6. The pressure in the expansion chamber R1 is higher than the pressure in the reservoir R by the pressure loss that occurs when the fluid discharged from the expansion chamber R1 passes through the expansion damping valve 15. Therefore, the actuator AC can not exert a thrust in a direction to push the piston 2 upward, and exerts a thrust in the opposite direction, that is, a direction to push the piston 2 downward. From the above, when making the suspension device S exert a thrust that pushes up the piston 2 upward, the actuator 2 is extended due to an external force, and when the pump 4 is stopped, the piston 2 is The thrust can not be exerted in the upward direction. Therefore, regardless of the valve opening pressure of the control valve V, the thrust of the actuator AC has the characteristic shown by the line (10) in FIG. This has the same effect as controlling the expansion damping force to the lowest damping force in the damping force variable damper.

  Normally, in semi-active suspension, when considering to perform skyhook control according to the Karnop rule using a damping force variable damper, if expansion side damping force (force in the direction to depress the piston) is required, extension operation Sometimes, the damping force of the damping force variable damper is controlled to a damping force capable of obtaining a target thrust. And at the time of contraction operation, since the expansion side damping force can not be obtained, it is controlled to exhibit the lowest damping force to the pressure side. On the other hand, when a compression side damping force (force in a direction to push up the piston) is required, the damping force of the damping force variable damper is controlled to a target thrusting force during contraction operation and compression side damping force is obtained during extension operation. It is controlled to exert the lowest damping force to the expansion side. On the other hand, in the suspension device S of the present invention, in a state where the pump 4 is stopped, when the actuator AC exerts a thrust that pushes the piston 2 downward, the thrust of the actuator AC is controlled at the time of extension operation It is controlled within the possible output range by adjusting the valve opening pressure of the valve V. On the other hand, at the time of contraction, even if the actuator AC tries to exert a thrust that pushes the piston 2 downward, the actuator AC exerts the lowest thrust among the thrusts that push the piston 2 upward. On the other hand, when causing the actuator AC to exert a thrust that pushes the piston 2 upward, the thrust of the actuator AC is controlled within the output available range by adjusting the valve opening pressure of the control valve V during the contraction operation. On the other hand, at the time of the extension operation, even if the actuator AC tries to exert a thrust that pushes the piston 2 upward, the actuator AC exerts the lowest thrust among the thrusts that push the piston 2 downward. Therefore, in the suspension device S of the present invention, when the pump 4 is stopped, it can automatically exhibit the same function as the semi-active suspension. This means that the suspension device S automatically functions as a semi-active suspension when the discharge flow rate of the pump 4 is less than the volume increase of the expansion side chamber R1 or the pressure side chamber R2 which is expanding even while the pump 4 is operating. It is shown that.

  Finally, the operation of the suspension device S will be described when the motor 13, the switching valve 9 and the control valve V of the suspension device S fail to be energized due to some abnormality. For example, the motor 13, the switching valve 9, and the control valve V can not be energized, and the motor 13, the switching valve 9, and the control valve are abnormal when abnormality is found in the controller C and the driver device Dr. This includes the case of stopping the power supply to V.

  At the time of failure, the motor 13, the switching valve 9 and the control valve V are de-energized or in a non-energizable state, the pump 4 is stopped, and the control valve V has the minimum valve opening pressure. 9 is in a state of being biased by the spring 9d and taking the expansion side supply position 9b.

  In this state, when the actuator AC is operated to be extended by an external force, the volume of the expansion chamber R1 is reduced, so the reduced amount of fluid is discharged from the expansion chamber R1 through the expansion damping valve 15 and controlled through the supply passage 5 It flows to the reservoir R through the valve V. In addition, since the supply side check valve 12 is provided, the fluid does not flow to the pump 4 side. On the other hand, the fluid corresponding to the volume expansion is supplied from the reservoir R via the discharge passage 6 to the pressure side chamber R2 whose volume is increased.

  Although the fluid discharged from the expansion chamber R1 passes through the control valve V, the pressure in the supply passage 5 is substantially equal to that of the reservoir because the fluid has a property that hardly gives resistance to the flow passing through when the control valve V is not energized. It becomes equal to the pressure of R. Therefore, the pressure in the expansion chamber R1 is higher than the pressure in the supply passage 5 by the pressure loss generated when the fluid discharged from the expansion chamber R1 passes through the expansion damping valve 15. Therefore, the reservoir by the pressure loss It becomes higher than the pressure of R.

  Therefore, the thrust of the actuator AC is a force obtained by multiplying the pressure loss due to the expansion damping valve 15 by the pressure receiving area of the expansion chamber R1 of the piston 2, and in the graph shown in FIG. It becomes the characteristic shown by). In this case, a force that is the product of the pressure of the pressure side chamber R2 and the pressure receiving area facing the pressure side chamber R2 of the piston 2 is generated as a thrust that pushes up the piston 2. However, since the pressure side chamber R2 has the same pressure as the reservoir R, and the pressure of the extension side chamber R1 is captured as a pressure difference with the pressure of the reservoir R, the thrust that pushes up the piston 2 can be regarded as zero.

  On the other hand, when the actuator AC contracts due to an external force, the volume of the pressure side chamber R2 decreases, so the fluid corresponding to the decrease 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, fluid corresponding to the volume expansion is supplied from the reservoir R from the reservoir R via the discharge passage 6 to the expansion side chamber R1 where the volume increases. In addition, since the supply side check valve 12 is provided, the fluid does not flow to the pump 4 side.

  Therefore, the pressure in the pressure side chamber R2 is higher than the pressure in the reservoir R by the pressure loss generated when the fluid discharged from the pressure side chamber R2 passes through the pressure side damping valve 17.

  Therefore, the thrust of the actuator AC is a force obtained by multiplying the pressure loss corresponding to 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. In the graph shown in FIG. It becomes the characteristic shown by. In this case, a force that is the product of the pressure of the expansion chamber R1 and the pressure receiving area facing the expansion chamber R1 of the piston 2 is generated as a thrust that pushes the piston 2 down. However, since the expansion side chamber R1 has the same pressure as the reservoir R, and the pressure of the pressure side chamber R2 is captured as a differential pressure with the pressure of the reservoir R, the thrust that pushes down the piston 2 can be regarded as zero.

  As described above, in the state where the suspension device S fails, the actuator AC functions as a passive damper to suppress the vibration of the vehicle body B and the wheel W, so that the fail safe operation is surely performed at the time of the failure.

  As described above, the suspension device S according to the present embodiment is provided on the upstream side of the control valve V in the middle of the control passage 19, and allows only the passage of fluid having a predetermined flow rate or less, A flow priority valve FPV is provided which discharges the excess flow rate into the reservoir R.

  According to this configuration, even when the total flow of the fluid discharged from the inside of the cylinder 1 at the time of expansion and contraction of the actuator AC and the fluid discharged from the pump 4 flows through the control passage 19, the control valve V Flow to Therefore, since excessive fluid force can be prevented from acting on the control valve V, it is possible to reliably prevent the control valve V from becoming difficult to control. Further, since the upper limit flow rate of the fluid flowing through the control valve V is determined by the flow priority valve FPV, the variation of the flow rate of the fluid flowing through the control valve V becomes small, and valve oscillation of the control valve V can be suppressed. Therefore, according to the suspension device S of this example, the control valve V can be stably controlled.

  In the flow priority valve FPV of this example, when the valve body 42 is seated on the valve seat 41, the pressure receiving area of the pressure received from the upstream side of the control passage 19 in the valve body 42 and the downstream side of the control passage The pressure receiving areas of the received pressure are set to be equal.

  Here, the force pushing the valve body 42 is determined by the product of the pressure acting on the valve body 42 and the pressure receiving area receiving the pressure. Therefore, if the pressure receiving area for receiving the pressure on the upstream side of the control passage 19 in the valve body 42 and the pressure receiving area for the pressure received from the downstream side differ when the valve body 42 is seated on the valve seat 41, the acting pressure Even if the pressure is equal pressure, the force pressing the valve body 42 from the side having a large pressure receiving area becomes stronger. Since the pressure upstream of the control valve V of the control passage 19 is controlled by the control valve V, the force pressing the valve body 42 becomes large when the valve opening pressure of the control valve V is high. When the valve opening pressure is small, the force pressing the valve body 42 is small. Then, the pressure at which the valve body 42 leaves the valve seat 41 also changes in accordance with the valve opening pressure of the control valve V.

  Therefore, when the pressure receiving area of the valve body 42 receiving the pressure on the upstream side of the control passage 19 is different from the pressure receiving area of the pressure received from the downstream side when the valve body 42 is seated on the valve seat 41, the control valve The flow rate of the fluid flowing to the control valve V fluctuates according to the valve opening pressure of V.

  On the other hand, as described above, when the valve body 42 is seated on the valve seat 41, the flow priority valve FPV of this example has a pressure receiving area for receiving the pressure on the upstream side of the control passage 19 in the valve body 42. The pressure receiving area of the pressure received from the downstream side is equal. Therefore, even if the valve opening pressure of the control valve V changes, the force pressing the valve body 42 does not change, and the flow rate of the fluid flowing to the control valve V can be made constant.

  However, even if the pressure receiving area for receiving the pressure on the upstream side of the control passage 19 in the valve body 42 and the pressure receiving area for the pressure received from the downstream side are different, a large flow of fluid can be prevented from flowing in the control valve V The object of the present invention can be achieved.

  Further, in the flow priority valve FPV shown in FIG. 4 of this example, the orifice O is provided in the valve body 42 to form the restricted passage 30, so another passage connecting the upstream of the control passage 19 and the downstream of the control passage 19 is The flow priority valve FPV can be made compact as well as being easier to manufacture than provided. However, the present invention can be realized even if another passage connecting the upstream of the control passage 19 and the downstream of the control passage 19 is provided.

  Further, as shown in FIG. 9, the control passage 19 may be provided with a bypass passage 50 for bypassing the control valve V, and the bypass passage 50 may be provided with an orifice 51 disposed in parallel with the control valve V.

  According to this configuration, the control passage 19 is communicated with the discharge passage 6 by the orifice 51 even if the control valve V is mechanically broken and is in the closed / closed state. Therefore, a pressure loss occurs when the fluid passes through the orifice O provided in the restriction passage 30, and a pressure difference between the upstream side and the downstream side of the control passage 19 in the flow priority valve FPV occurs by the pressure loss. Thus, in the present embodiment, the control valve V is closed and the valve body 42 is detached from the valve seat 41 if the pressure on the upstream side of the control valve V becomes high, as the control valve V is closed. The pressure on the more upstream side can be relieved to the reservoir R through the return passage 31.

  Further, in the example of FIG. 9, since the flow priority valve FPV functions as a relief valve for releasing the pressure on the upstream side of the control valve V when the control valve V breaks down and enters the closed / closed state, the fluid pressure circuit FC There is no need to separately provide a relief valve.

  Furthermore, since the orifice 51 provided in the bypass path 50 is merely a throttling, there is no mechanical failure, so it is a case where the control valve V has a mechanical failure and is in a closed state. However, the control passage 19 can be reliably communicated.

  If the flow resistance of the orifice 51 of the present embodiment is too small and the control valve V is not broken, as long as the flow rate flowing into the control passage 19 is small, the bypass is provided with the orifice 51 preferentially. It flows into the road 50. Therefore, if the flow path resistance of the orifice 51 is set too small, the control range of the pressure that can be controlled by the control valve V when the control valve V is not broken becomes narrow.

  Conversely, if the flow path resistance of the orifice 51 is increased too much, the damping force of the actuator AC that functions as a passive damper becomes too high when the control valve V mechanically fails, and the suspension device S It makes the rider of the mounted vehicle feel stiff.

  Therefore, the diameter of the orifice 51 may be arbitrarily determined in consideration of the control range of the pressure that can be controlled by the control valve V when the control valve V is not faulty and the damping force of the actuator AC at the time of fault.

  Further, in the present embodiment, the expansion side damping element VE which is provided in the expansion side passage 7 and provides resistance to the flow from the expansion side chamber R1 to the switching valve 9 and allows the flow in the opposite direction, A pressure-side damping element VC is provided which is provided in the passage 8 and which resists the flow from the pressure-side chamber R2 to the switching valve 9 and which allows the flow in the opposite direction.

  According to this configuration, not only can the actuator AC be positively expanded and contracted to function as an active suspension, but also in a scene where the exertion of thrust as a semi-active suspension is expected, the driving of the pump 4 is not essential. Energy consumption is reduced because driving is required only when driving 4 is required. Therefore, according to the suspension device S of the present invention, it is possible to function as an active suspension and reduce energy consumption.

  However, in the suspension device S of this example, the expansion damping element VE and the compression damping element VC may be omitted. Even when the expansion damping element VE and the compression damping element VC are omitted, the flow rate obtained by superimposing the fluid discharged from the inside of the cylinder 1 when the actuator AC expands and contracts and the fluid discharged from the pump 4 Since the fluid flows, the flow rate of the fluid flowing to the control valve V becomes a large flow rate. Therefore, by providing the flow priority valve FPV on the upstream side of the control valve V, the flow rate of the fluid flowing to the control valve V can be reduced to a predetermined flow rate or less, and the effect of the present invention capable of stably controlling the control valve V can be achieved.

  While the preferred embodiments of the present invention have been described above in detail, it goes without saying that modifications, variations and changes can be made without departing from the scope of the claims.

Reference Signs List 1 cylinder 4 pump 5 supply passage 6 discharge passage 7 extension side passage 8 pressure side passage 9 switching valve 10 · · Suction passage, 11 · · · suction check valve, 12 · · · supply side check valve, 19 · · · control passage, 30 · · · restriction passage, 31 · · · return passage, 41 · · · seat, 42: valve body, 51: orifice, AC: actuator, FPV: flow priority valve, O: orifice, R: reservoir, R1: expansion side chamber, R2: R2: Pressure side chamber, S: Suspension device, SP: Biasing spring (biasing member), V: Control valve, VC: Pressure side damping element, VE: Expansion side damping element

Claims (4)

An actuator comprising: a cylinder; and a piston movably inserted in the cylinder to divide the inside of the cylinder into an expansion side chamber and a compression side chamber.
With the pump,
A reservoir connected to the suction side of the pump;
A supply passage connected to the discharge side of the pump;
An outlet connected to the reservoir;
An expansion side passage connected to the expansion side chamber;
A pressure side passage connected to the pressure side chamber;
A switching valve that selectively connects one of the extension side passage and the pressure side passage to the supply path and connects the other of the extension side passage and the pressure side passage to the discharge path;
A control passage provided with a control valve capable of adjusting the pressure of the supply passage according to a supply current;
A suction passage connecting the supply passage and the discharge passage;
A suction check valve provided in the middle of the suction passage to allow only the flow of fluid from the discharge passage toward the supply passage;
A supply-side check valve provided midway in the supply path between the control valve and the pump and permitting only the flow of fluid from the pump side to the control valve side;
The flow priority valve is provided on the upstream side of the control valve in the middle of the control passage, and allows only the passage of fluid having a predetermined flow rate or less, and the excess flow rate exceeding the predetermined flow rate is discharged to the reservoir. Suspension apparatus characterized by having. The flow priority valve is
A restricted passage having an orifice connecting upstream and downstream of the control passage and providing resistance to the flow of fluid passing therethrough;
A return passage branched from upstream of the orifice of the restricted passage and leading to the reservoir;
A valve seat provided in the middle of the return passage; a valve body that is seated on the valve seat to open and close the return passage; and a biasing member that biases the valve body toward the valve seat. Have
The pressure on the upstream side of the control passage is exerted on the valve body in the valve opening direction, and the pressure on the downstream side of the control passage is exerted in the valve closing direction,
When the valve body is seated on the valve seat, the pressure receiving area of the pressure received from the upstream side of the control passage in the valve body is equal to the pressure receiving area of the pressure received from the downstream side of the control passage. The suspension device according to claim 1. The suspension device according to claim 1, wherein an orifice is provided in the control passage in parallel with the control valve. An expansion damping element provided in the expansion passage for resisting the flow from the expansion chamber toward the switching valve and allowing it to flow in the opposite direction;
4. A pressure side damping element provided in the pressure side passage for providing resistance to the flow from the pressure side chamber to the switching valve and permitting the flow in the opposite direction. The suspension apparatus according to any one of the above.

Images