JP2019124312A - Hydraulic shock absorber - Google Patents

Abstract

To provide a hydraulic shock absorber having low expansion/contraction speed, capable of adjusting generation force, and further capable of improving ride comfort in a vehicle.SOLUTION: In order to achieve above-mentioned goal, problem solution means of this invention comprises: a cylinder 1; a piston 2 sectioning the cylinder 1 into an expansion side chamber R1 and a compression side chamber R2; passages EP, CP communicating between the expansion side chamber R1 and the compression side chamber R2; an electromagnetic pressure regulating valve EV provided in the passages EP, CP, and capable of adjusting valve opening pressure by adjusting pressure in a pilot passage 12 communicating between the expansion side chamber R1 and the compression side chamber R2; a pump P; and a motor 4 configured to drive the motor P, in which liquid discharged from the pump P can be supplied selectively to one of the expansion side chamber R1 and the compression side chamber R2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic shock absorber.

  Some hydraulic shock absorbers used for vehicles have variable damping force, and the structure includes, for example, a cylinder, a rod side chamber and a piston side chamber partitioned by pistons in the cylinder, a reservoir, and an expansion side chamber. And a passage connecting the pressure side chamber and a damping force variable valve provided in the passage.

  The damping force variable valve includes a main valve provided in the passage for opening and closing the passage, and a pilot passage provided with a throttle in the middle to reduce pressure upstream of the passage and guide it as a back pressure biasing the main valve in the closing direction A solenoid controlled by a single solenoid, having a pressure control valve provided downstream of the throttle of the pilot passage to control the back pressure and an on-off valve integrated with the pressure control valve to open and close the pilot passage And a valve (see, for example, Patent Document 1).

  According to this hydraulic shock absorber, the damping force can be adjusted by a single damping force variable valve, and the valve opening pressure of the main valve is adjusted, so the differential pressure between the expansion chamber and the pressure chamber can be controlled according to the current. The desired damping force is obtained.

JP, 2015-59573, A

  In the liquid pressure shock absorber, the damping force variable valve includes the pilot passage connecting the expansion side chamber and the compression side chamber, so the expansion side chamber and the compression side chamber are also in communication through the pilot passage.

  Therefore, when the expansion / contraction speed of the hydraulic shock absorber is low, the liquid passes through the pilot passage to move back and forth between the expansion side chamber and the pressure side chamber even if the flow rate is small and the main valve does not open, as shown in FIG. In the hydraulic shock absorber, there are regions U1 and U2 in which the damping force (generated force) generated by the hydraulic shock absorber can not be output no matter how the valve opening pressure of the main valve is adjusted.

  If it is possible to adjust the generated force in this area, the generated force can be adjusted even in a state in which the expansion and contraction speed is low, which can contribute to the improvement of the riding comfort in the vehicle.

  Therefore, the present invention has been made to solve the above-mentioned problems, and the object of the present invention is a hydraulic shock absorber capable of adjusting the generated force even at a low expansion and contraction speed and improving the ride comfort in a vehicle. Offer.

  In order to achieve the above object, the problem solution means of the present invention is provided in a cylinder, a piston which divides the inside of the cylinder into an expansion side chamber and a compression side chamber, a passage connecting the expansion side chamber and the compression side chamber, The electromagnetic pressure control valve whose valve opening pressure can be adjusted by adjusting the pressure in the pilot passage that connects the expansion side chamber and the pressure side chamber, the pump, and the motor for driving the pump And one of the pressure side chambers can be selected and supplied. As described above, since the hydraulic shock absorber according to the present invention includes the pump in addition to the electromagnetic pressure control valve, the generated force can be adjusted even at a low expansion and contraction speed, and the ride quality in the vehicle can be improved.

  Also, the hydraulic shock absorber can communicate with the accumulator accumulated by the pump, the pump and the accumulator by selecting one of the expansion side chamber and the pressure side chamber, and can shut off the pump and the accumulator from the expansion side chamber and the pressure side chamber. It may be configured to include a switching valve. Thus, when the hydraulic shock absorber is configured, the response delay due to the inertia of the pump and the motor for driving the pump can be eliminated, and the differential pressure between the expansion side chamber and the pressure side chamber can be controlled as intended. Since the generated force does not drop, the ground contact load can be more stable and the ride quality of the vehicle can be further improved.

  Furthermore, the hydraulic shock absorber may include a controller that controls the current supplied to the electromagnetic pressure control valve and the motor based on the target pressures of the expansion chamber and the compression chamber. When the hydraulic shock absorber is configured as described above, since the current command is obtained from the pressure command, it is not necessary to separately obtain control of the electromagnetic pressure control valve and the motor from separate commands, and the generated force of the hydraulic shock absorber is very high. Easy to control.

  The hydraulic shock absorber has a reservoir, a base valve that allows only the flow of liquid from the pressure chamber to the reservoir and resists the flow of liquid, and a suction that allows only the flow of liquid from the reservoir to the pressure chamber. A passage may be provided. By configuring the hydraulic shock absorber in this way, even in a single-rod type shock absorber in which the piston rod is inserted only into the expansion side chamber, the electromagnetic pressure adjustment is performed while compensating for the volume of the piston rod when advancing and retracting into the cylinder. The generated force adjustment by the valve and the generated force adjustment by the pump can be performed.

Also, the hydraulic shock absorber is interposed between the sprung member and the unsprung member in the vehicle,
The motor may be configured to generate a torque that is proportional to the vertical velocity of the sprung member. In the hydraulic shock absorber configured in this way, the skyhook control can suppress the vibration of the sprung member.

  Furthermore, the hydraulic shock absorber is interposed between the sprung member and the unsprung member in the vehicle, and the motor is controlled to generate a torque proportional to the absolute value of the vertical velocity of the sprung member, and the switching valve May be switch-controlled by the direction of the vertical velocity of the sprung member. In the hydraulic shock absorber configured in this way, the skyhook control can suppress the vibration of the sprung member.

  In the hydraulic shock absorber, the passage has an extension passage and a pressure passage, and the electromagnetic pressure control valve has an extension damping valve provided in the extension passage, a pressure damping valve provided in the pressure passage, and an extension chamber. A pilot passage communicating with the pressure side chamber, and an electromagnetic valve provided in the pilot passage, and a pressure upstream of the solenoid valve in the pilot passage as a pilot pressure urging the expansion side damping valve and the pressure side damping valve in the closing direction. It may be led and it may be constituted so that pressure may be adjusted with a solenoid valve and valve-opening pressure of expansion side damping valve and pressure side damping valve may be adjusted. Thus, when the hydraulic shock absorber is configured, it is not necessary to use two electromagnetic damping valves, an electromagnetic damping valve that controls a generation force at extension and a solenoid damping valve that controls a generation force at contraction, but one electromagnetic The valve can control the generated force on both sides of the expansion and contraction. Therefore, according to this hydraulic shock absorber, since the generated force on the extension side and the generated force on the contraction side can be controlled by the control of the solenoid valve and the motor, the cost can be reduced.

  The hydraulic shock absorber is set such that the opening pressure of the expansion damping valve and the compression damping valve increases as the amount of current supplied to the solenoid valve increases, and the direction of the expansion / contraction direction and the force to be generated are the same. In this case, the target current indicating the amount of current of the solenoid valve may be configured to be maximized. The hydraulic shock absorber configured in this manner saves energy when functioning as an actuator.

  As described above, according to the fluid pressure shock absorber of the present invention, the generated force can be adjusted even if the expansion and contraction speed is low, and the ride comfort in the vehicle can be improved.

It is a block diagram of a hydraulic pressure shock absorber in a first embodiment. It is the graph which showed the extension speed and generated force characteristic of the hydraulic shock absorber. It is a block diagram of a controller. It is a block diagram of the hydraulic pressure shock absorber in 2nd embodiment. It is the graph which showed the extension speed of the conventional hydraulic shock absorber, and the characteristic of generated force.

  Hereinafter, the present invention will be described based on the respective embodiments shown in the drawings. In the description of the hydraulic shock absorbers D1 and D2 of the respective embodiments, the same reference numerals are attached to members common to the several embodiments, and the description is the same as that described in the one embodiment. Description of members in the other embodiments is omitted.

First Embodiment
The hydraulic shock absorber D1 in the first embodiment is, as shown in FIG. 1, a cylinder 1, a piston 2 that divides the inside of the cylinder 1 into an expansion chamber R1 and a compression chamber R2, and a piston 2 in this example. A piston rod 3 which is movably inserted into the cylinder 1, an expansion side passage EP as a passage communicating the expansion side chamber R 1 and the pressure side chamber R 2, a pressure side passage CP, and an electromagnetic pressure control valve EV; A pump P, a motor 4 for driving the pump P, and a controller C for controlling the electromagnetic pressure control valve EV and the motor 4 are provided. It is used by being interposed between certain wheels.

  Hereinafter, the hydraulic shock absorber D1 will be described in detail. In the present embodiment, as shown in FIG. 1, the hydraulic shock absorber D1 is provided in the reservoir R communicated with the pressure side chamber R2 via the discharge passage DP and the suction passage SP, and in the discharge passage DP. And a base valve BV that allows only the flow of liquid from the pressure side chamber R2 to the reservoir R and resists the flow of liquid, and only the flow of liquid from the reservoir R toward the pressure side chamber R2 provided in the suction passage SP It has an allowable check valve CV.

  The cylinder 1 is filled with a liquid such as hydraulic oil, and the reservoir R is filled with a gas in addition to the liquid. In addition to the above-described hydraulic oil, water, an aqueous solution, or the like can be used as the liquid used for the hydraulic pressure buffer D1.

  In this example, the electromagnetic pressure control valve EV is a pilot passage that connects the expansion damping valve 10 provided in the expansion channel EP, the compression damping valve 11 provided in the compression channel CP, and the expansion chamber R1 and the compression chamber R2. 12 and a solenoid valve 13 provided in the pilot passage 12.

  The pilot passage 12 is in communication with the expansion side chamber R1 and the pressure side chamber R2, and specifically, the upstream path 14 allowing the inflow of liquid from the higher pressure chamber of the expansion side chamber R1 and the pressure side chamber R2. And a downstream passage 15 for allowing liquid to flow into one of the expansion-side chamber R1 and the compression-side chamber R2, which has a lower pressure, and a pilot pressure control passage 16 for connecting the upstream passage 14 and the downstream passage 15.

  The upstream passage 14 communicates with the expansion side chamber R1 and the pressure side chamber R2, and a pair of check valves 17 are installed opposite each other in the middle so that the expansion side chamber R1 and the pressure side chamber R2 are upstream. It has eighteen.

  The downstream passage 15 communicates with the expansion side chamber R1 and the pressure side chamber R2, and a pair of check valves 19 and 20 are installed in the opposite directions so that the expansion side chamber R1 and the pressure side chamber R2 become downstream in the middle. Is equipped.

  The pilot pressure control passage 16 connects between the check valves 17 and 18 of the upstream passage 14 and between the check valves 19 and 20 of the downstream passage 15. When the pressure in the expansion chamber R1 is higher than the pressure in the compression chamber R2, the liquid in the expansion chamber R1 pushes the check valve 17 open to enter the upstream passage 14 and passes through the pilot pressure control passage 16 to the downstream passage. The 15 check valves 20 are opened to flow into the pressure side chamber R2. On the other hand, when the pressure in the pressure side chamber R2 is higher than the pressure in the expansion side chamber R1, the liquid in the pressure side chamber R2 pushes open the check valve 18 to enter the upstream passage 14 and passes through the pilot pressure control passage 16 Then, the check valve 19 of the downstream passage 15 is opened to flow to the expansion side chamber R1. Since the pilot passage 12 is configured as described above, the liquid flowing through the pilot pressure control passage 16 always flows from the upstream passage 14 side toward the downstream passage 15 side.

  A throttle 21 and a solenoid valve 13 are disposed in series in the middle of the pilot pressure control passage 16. The solenoid valve 13 can adjust the valve opening pressure according to the amount of current supplied. Therefore, by adjusting the amount of current supplied to the solenoid valve 13, the pressure upstream of the throttle 21 of the pilot pressure control passage 16 and upstream of the solenoid valve 13 can be controlled by the valve opening pressure of the solenoid valve 13. As the value is larger, the valve opening pressure of the solenoid valve 13 is set to be larger.

  The expansion damping valve 10 is provided in the middle of the expansion passage EP, and the pressure in the expansion chamber R1 acts in the valve opening direction, and the pressure between the throttle 21 of the pilot pressure control passage 16 and the solenoid valve 13 The pilot pressure acts in the valve closing direction, and further, the biasing force by the spring acts in the valve closing direction. Therefore, if the force by which the expansion side damping valve 10 is opened by the pressure on the upstream side of the extension side chamber R1 exceeds the force by which the expansion side damping valve 10 is closed by the action of the pilot pressure and the spring. It opens to resist the flow of liquid passing through.

  As described above, in the expansion damping valve 10, the valve opening pressure is changed by the adjustment of the pilot pressure because the valve is biased in the valve closing direction by the pilot pressure. And since the pilot pressure is controlled by the solenoid valve 13 as described above, the valve opening pressure of the expansion side damping valve 10 can be adjusted by the amount of current supplied to the solenoid valve 13.

  The pressure side damping valve 11 is provided in the middle of the pressure side passage CP, and the pressure of the pressure side chamber R2 acts in the valve opening direction, and the pressure between the throttle 21 of the pilot pressure control passage 16 and the solenoid valve 13 is a pilot pressure It acts in the valve closing direction, and furthermore, the biasing force by the spring acts in the valve closing direction. Therefore, the pressure side damping valve 11 is opened when the force to open the pressure side damping valve 11 by the pressure on the upstream side of the pressure side chamber R2 exceeds the force to close the pressure side damping valve 11 by the pilot pressure and the action of the spring. To resist the flow of liquid passing through.

  As described above, in the pressure-side damping valve 11, since the pilot pressure is biased in the valve closing direction, the valve opening pressure is changed by the adjustment of the pilot pressure. And since the pilot pressure is controlled by the solenoid valve 13 as described above, the valve opening pressure of the pressure side damping valve 11 can be adjusted by the amount of current supplied to the solenoid valve 13. Therefore, in the electromagnetic pressure control valve EV of this example, the valve opening pressure of the expansion side damping valve 10 and the pressure side damping valve 11 can be adjusted according to the amount of current supplied to the solenoid valve 13. As the amount of current supplied to the solenoid valve 13 becomes larger, the valve opening pressures of the expansion side damping valve 10 and the pressure side damping valve 11 become larger.

  Subsequently, the pump P is a bi-directional discharge gear pump or vane pump driven by the motor 4 or a reversible pump motor similar to these in this example, and the expansion side chamber R1 and the pressure side chamber R2 It is provided in the middle of the pump passage 22 which communicates. When the motor 4 is energized and the pump P is rotated forward, the pump P sucks the liquid from the pressure chamber R2 and sends it to the expansion chamber R1, and when the pump P is reversed, the pump P sucks the liquid from the expansion chamber R1 and the pressure chamber R2 Send to That is, the hydraulic pressure shock absorber D of this example can supply the liquid discharged by the pump P by selecting one of the expansion side chamber R1 and the pressure side chamber R2.

  Since the liquid is supplied from the pressure side chamber R2 to the expansion side chamber R1 when the pump P is rotated forward, the hydraulic shock absorber D1 can be positively contracted, and when the pump P is reversed, the liquid from the expansion side chamber R1 to the pressure side chamber R2 Thus, the hydraulic shock absorber D1 can be actively extended. From this, the hydraulic shock absorber D1 can function as an actuator by the drive of the pump P.

  Subsequently, the operation of the hydraulic shock absorber D1 when the pump P is stopped will be described. When the hydraulic shock absorber D1 exhibits an extension operation of moving the piston 2 upward in FIG. 1 with respect to the cylinder 1 by an external force when the pump P is stopped, the expansion side passage EP is extended from the expansion side chamber R1 where the liquid is compressed. And move to the pressure side chamber R2. In addition, a volume of liquid from which the piston rod 3 exits from the cylinder 1 is supplied from the reservoir R into the cylinder 1 through the suction passage SP.

  During the expansion operation of the hydraulic shock absorber D1, the expansion damping valve 10 opens with respect to the flow of the liquid passing through the expansion passage EP, and the pressure in the expansion chamber R1 becomes equal to that of the expansion damping valve 10. The valve opening pressure is controlled. Therefore, the hydraulic pressure shock absorber D1 outputs the generated force in the direction in which the piston 2 is pushed down with respect to the extension in the first quadrant of the characteristic graph of the expansion / contraction speed and the generated force in FIG. As the extension speed of the hydraulic shock absorber D1 increases, a pressure loss occurs when the liquid passes through the expansion damping valve 10. Therefore, as shown in the first quadrant in FIG. 2, the extension speed increases. A pressure override characteristic appears in which the pressure in the expansion side chamber R1 is larger than the valve opening pressure. Further, since the valve opening pressure of the expansion damping valve 10 can be adjusted by the solenoid valve 13, the hydraulic shock absorber D1 is generated in the first quadrant of the graph in FIG. 2 according to the amount of current supplied to the solenoid valve 13. The generated force can be adjusted in the range from line G1 to line G2. Further, even if the expansion damping valve 10 is closed, the liquid can move from the expansion chamber R1 to the compression chamber R2 via the pilot passage 12. Therefore, in the first quadrant in FIG. In the region, there is a region Z1 (the shaded region in FIG. 2) in which the hydraulic pressure shock absorber D1 can not generate a force when the pump P is stopped.

  When the hydraulic shock absorber D1 exhibits a contraction operation in which the piston 2 moves downward in FIG. 1 with respect to the cylinder 1 by an external force when the pump P is stopped, the pressure side passage CP is It passes and moves to expansion side room R1. Further, a volume of liquid in which the piston rod 3 enters the cylinder 1 is discharged from the pressure side chamber R2 to the reservoir R through the discharge passage DP to the reservoir R.

  When the hydraulic shock absorber D1 is contracted, the pressure damping valve 11 opens with respect to the flow of liquid passing through the pressure passage CP, and the pressure in the pressure chamber R2 is equal to the valve opening pressure of the pressure damping valve 11. Controlled by Therefore, the hydraulic pressure shock absorber D1 outputs a generated force in a direction to push up the piston 2 against contraction in the third quadrant in FIG. Since the pressure loss occurs when the liquid passes through the pressure-side damping valve 11 when the contraction speed of the hydraulic shock absorber D1 increases, as shown in the third quadrant in FIG. A pressure override characteristic appears in which the pressure in the chamber R2 becomes larger than the valve opening pressure. Further, since the valve opening pressure of the pressure side damping valve 11 can be adjusted by the solenoid valve 13, the occurrence of the occurrence of the hydraulic shock absorber D1 according to the amount of current supplied to the solenoid valve 13 in the third quadrant of the graph in FIG. The force can be adjusted in the range of line G3 to line G4. Further, even if the pressure side damping valve 11 is closed, the liquid can move from the pressure side chamber R2 to the extension side chamber R1 via the pilot passage 12, so that the extension speed is extremely low in the third quadrant in FIG. In the case where the pump P is stopped, there is an area Z2 (shaded area in FIG. 2) in which the hydraulic pressure shock absorber D1 can not generate force.

  Next, the operation when driving the pump P to cause the hydraulic shock absorber D1 to function as an actuator will be described. In the hydraulic shock absorber D1, when the pump P is rotated forward, the pump P sucks up the liquid from the pressure side chamber R2 and the liquid is supplied to the expansion side chamber R1 to generate a contraction operation so as to push down the piston 2 Output power. Since the piston rod 3 enters the cylinder 1 by the contraction operation of the hydraulic shock absorber D1, the surplus liquid in the cylinder 1 is discharged to the reservoir R via the discharge passage DP. Since the discharge pressure of the pump P can be adjusted by the amount of current supplied to the motor 4, the amount of current supplied to the motor 4 can control the generated force on the contraction side of the hydraulic shock absorber D1. The valve opening pressure of the expansion damping valve 10 may be set higher than the pressure of the expansion chamber R1 controlled by the pump P. In this case, the pump P discharges the flow moving from the expansion chamber R1 to the pressure chamber R2 via the pilot passage 12 and the flow necessary to contract the hydraulic shock absorber D1. In the present example, in order to maximize the valve opening pressure of the expansion damping valve 10, the target current for instructing the amount of current supplied to the solenoid valve 13 is maximized.

  Since the discharge flow rate of the pump P is limited and the setting of the valve opening pressure of the expansion damping valve 10 is also limited, when the hydraulic shock absorber D1 functions as an actuator and contracts, the second quadrant in FIG. 2 The generated force can be exerted within the range surrounded by the X axis, the Y axis, the line A1 and the line A2. Line A1 shows the limit by setting of expansion side damping valve 10, and line A2 shows the limit which can not generate power by the flow rate limit of pump P.

  When the hydraulic shock absorber D1 reverses the pump P, the pump P sucks the liquid from the expansion side chamber R1 and the liquid is supplied to the pressure side chamber R2 so that the generated force in the direction to push up the piston 2 by exhibiting the expansion operation. Output Since the piston rod 3 is withdrawn from the inside of the cylinder 1 by the extension operation of the hydraulic shock absorber D1, the liquid lacking in the cylinder 1 is supplied from the reservoir R via the suction passage SP. Since the discharge pressure of the pump P can be adjusted by the amount of current supplied to the motor 4, the amount of current supplied to the motor 4 can control the generated force on the extension side of the hydraulic shock absorber D1. The valve opening pressure of the pressure side damping valve 11 may be made higher than the pressure of the pressure side chamber R2 controlled by the pump P. In this case, the pump P discharges the flow rate moving from the pressure side chamber R2 to the expansion side chamber R1 through the pilot passage 12 and the flow rate necessary for extending the hydraulic shock absorber D1. In the present example, in order to maximize the valve opening pressure of the pressure side damping valve 11, the target current for instructing the amount of current supplied to the solenoid valve 13 is maximized.

  Since the discharge flow rate of the pump P is limited and the setting of the valve opening pressure of the pressure side damping valve 11 is also limited, when the hydraulic shock absorber D1 functions as an actuator and contracts, the fourth quadrant in FIG. The generated force can be exerted within the range surrounded by the X axis, the Y axis, the line A3 and the line A4. Line A3 shows the limit by setting of pressure side damping valve 11, and line A4 shows the limit which can not generate power by the flow rate limit of pump P.

  Furthermore, the operation in the case of driving the pump P when the hydraulic shock absorber D1 is expanded and contracted by an external force will be described. When the hydraulic shock absorber D1 is expanded by an external force, if the pump P is rotated forward to feed the liquid from the pressure side chamber R2 to the expansion side chamber R1, the pressure in the expansion side chamber R1 can be controlled by the pump P . Then, when the pump P is stopped, the hydraulic shock absorber D1 outputs the generated force even if it is in the area Z1 in which the generated force can not be output when the expansion speed of the hydraulic shock absorber D1 is low when the pump is stopped. become able to.

  Also, since the expansion damping valve 10 gives resistance to the flow of liquid, a pressure override characteristic appears, but the pump P is reversed so that the liquid is moved from the expansion chamber R1 to the pressure chamber R2 via the pump P. If so, the pressure in the expansion chamber R1 can be reduced. Therefore, the pressure override characteristic appears only by the pressure control by the electromagnetic pressure regulating valve EV, but the override can be cut by the reverse rotation of the pump P when the hydraulic shock absorber D1 is extended by an external force, and the pressure in the expansion chamber R1 It will be possible to bring it closer to the target pressure. At this time, the pump P is generating a brake at a designated pressure or is reversely driven. Whether the pump P is to be braked or driven reversely is determined by the torque control of the motor itself.

  Furthermore, when the hydraulic shock absorber D1 is contracted by an external force, if the pump P is reversely rotated to feed the liquid from the expansion side chamber R1 to the pressure side chamber R2, the pressure in the pressure side chamber R2 can be controlled by the pump P Become. Then, when the pump P is reversed even if the pump P is reversed, the hydraulic shock absorber D1 outputs the generated force even if the pump P is reversed even when the pump P is stopped even when the contraction speed of the hydraulic shock absorber D1 is low when the pump stops. become able to.

  Also, the pressure override characteristic appears because the pressure-side damping valve 11 resists the flow of liquid, but the pump P is rotated forward to move the liquid from the pressure-side chamber R2 to the expansion-side chamber R1 via the pump P. If so, the pressure in the pressure side chamber R2 can be reduced. Therefore, the pressure override characteristic appears only by the pressure control by the electromagnetic pressure adjustment valve EV, but the override can be cut by the forward rotation of the pump P when the hydraulic shock absorber D1 contracts due to an external force. The pressure can be brought close to the targeted pressure. At this time, the pump P generates a brake at a specified pressure or is driven to rotate forward. Whether the pump P is to be braked or driven to rotate forward is determined by torque control of the motor itself.

  When the pump P is rotated by the flow of liquid due to the expansion and contraction of the hydraulic pressure damper D1, when the motor 4 is rotationally driven by the pump P, the motor 4 also functions as a generator. When the hydraulic shock absorber D1 operates in the first quadrant and the third quadrant in FIG. 2, if the regenerative current of the motor 4 is chopped or controlled, the resistance given by the pump P to the flow of liquid is adjusted. The pump P can be used to control the pressure in the expansion chamber R1 and the pressure chamber R2. As described above, the pressure of the expansion side chamber R1 and the pressure side chamber R2 can be controlled by either the electromagnetic pressure regulating valve EV or the pump P, and the pressure can be controlled by both the electromagnetic pressure regulating valve EV and the pump P. However, if the valve opening pressure of the electromagnetic pressure control valve EV and the discharge pressure of the pump P are equal, there may be a situation where both are in balance and the pump P and the motor 4 stop in principle. In practice, there is no pressure override in the electromagnetic pressure control valve EV, so this does not happen, but just in advance, slightly shift the valve opening pressure of the electromagnetic pressure control valve EV and the discharge pressure of the pump P It is good. In addition, when the set pressure of the solenoid pressure adjustment valve EV is increased, the motor 4 is easily rotated, so that a regenerative current can be generated efficiently.

  Subsequently, as shown in FIG. 3, the controller C can control the current of the solenoid valve 13 and the motor 4 in the solenoid pressure regulating valve EV. The controller C includes current sensors S1 and S2 for detecting the amount of current flowing through the solenoid valve 13 and the motor 4, and a stroke sensor S3 for detecting the stroke of the hydraulic shock absorber D1. Control the current flowing to 4. The controller C obtains a pressure command instructing the differential pressure in the expansion chamber R1 and the pressure chamber R2 from the generated force required for the hydraulic shock absorber D1, and instructs the amount of current of the solenoid valve 13 and the motor 4 from this pressure command. Request the current command. Then, the controller C supplies a current such that the amount of current flowing through the solenoid valve 13 and the motor 4 conforms to the current command. In this example, in order to realize skyhook control, the controller C obtains the generated force required for the hydraulic pressure shock absorber D1 from information on the vertical velocity of the vehicle body from the outside, Calculate the generated force by multiplying the skyhook damping coefficient. The generated force is generated according to the differential pressure between the expansion side chamber R1 and the pressure side chamber R2 of the hydraulic pressure shock absorber D1, so the differential pressure between the expansion side chamber R1 and the pressure side chamber R2 can be uniquely determined from the generated force. The controller C may include an acceleration sensor that detects the vertical acceleration of the vehicle body so that the information on the vertical velocity of the vehicle body can be obtained by itself.

  The controller C obtains a stroke speed from the stroke of the hydraulic shock absorber D1 detected by the stroke sensor S3, and obtains a pressure command based on the stroke speed and the generated force. Since the differential pressure instructed by the pressure command changes in accordance with the amount of current supplied to the electromagnetic pressure control valve EV and the motor 4, a current command instructing the amount of current can be obtained from the pressure command. Therefore, the controller C obtains a current command that instructs the amount of current to be supplied to the solenoid valve 13 and the motor 4 from the pressure command.

  When the generated force in the same direction as the expansion and contraction direction of the liquid pressure shock absorber D1 is required, or when the generated force is in the areas Z1 and Z2, the pump P needs to be driven. The controller C performs torque control for the motor 4 that drives the pump P, and the target torque is proportional to the value obtained by multiplying the speed in the vertical direction of the vehicle body by the skyhook damping coefficient. In this way, the controller C can realize skyhook control with the hydraulic pressure damper D1 and suppress the vibration of the vehicle body. Therefore, with regard to driving and braking of the pump P, for example, a dedicated microcomputer may be provided in the controller C and the current may be controlled by the torque control of the motor 4. In this example, in order to determine which state is in the first quadrant to the fourth quadrant and to cooperate with the electromagnetic pressure regulating valve EV, information on the stroke speed of the hydraulic shock absorber D1 is required. So, in this example, the controller C is provided with stroke sensor S3. The controller C uses the stroke speed obtained from the stroke sensor S3 to determine which quadrant in FIG. 2 the expansion and contraction state of the hydraulic shock absorber D1 is in.

  Then, when the generated force to be output to the hydraulic pressure damper D1 is in the second quadrant and the fourth quadrant in FIG. 2, the controller C maximizes the target current indicating the amount of current supplied to the solenoid valve 13 and the current While supplying, the torque control of the motor 4 is performed according to the vertical speed of the vehicle body to cause the hydraulic pressure shock absorber D1 to function as an actuator to suppress the movement of the vehicle body. In this way, the liquid does not pass through the expansion damping valve 10 and the compression damping valve 11, and the torque generated by the hydraulic shock absorber D1 can be controlled by the torque of the motor 4, thereby saving energy.

  Further, the generated force to be output to the hydraulic shock absorber D1 is in the first quadrant and the third quadrant in FIG. 2 and is not in the area Z1 and the area Z2, and the output of the generated force only by the pressure control by the electromagnetic pressure regulating valve EV. If it is possible, the controller C does not supply current to the motor 4, but controls the back electromotive force generated by the motor 4 with a circuit that regenerates the motor 4, and eliminates overriding by the electromagnetic pressure adjustment valve EV. An effective current corresponding to the pressure control target value is regenerated to the power supply side of the motor 4.

  Thus, the controller C obtains information on the required generation force to be output to the hydraulic pressure shock absorber D1 and the stroke speed of the hydraulic pressure shock absorber D1, obtains a pressure command, and based on the pressure command, the motor 4 and By adjusting the amount of current supplied to the solenoid valve 13, generated force can be generated in the hydraulic shock absorber D1 in each of the reflections in FIG. As described above, since the current command is obtained from the pressure command, it is not necessary to separately obtain the control of the electromagnetic pressure regulating valve EV and the motor 4 from different commands, and the generation force of the hydraulic shock absorber D1 can be very easily controlled. .

  The hydraulic shock absorber D1 of the present invention includes a cylinder 1, a piston 2 that divides the interior of the cylinder 1 into an expansion chamber R1 and a compression chamber R2, passages EP and CP that communicate the expansion chamber R1 with the compression chamber R2, The electromagnetic pressure control valve EV, which is capable of adjusting the valve opening pressure by adjusting the pressure in the pilot passage 12 provided in the passages EP and CP and communicating the expansion side chamber R1 and the pressure side chamber R2, drives the pump P and the pump P A motor 4 is provided to select one of the expansion side chamber R1 and the pressure side chamber R2 for the liquid discharged by the pump P to supply the liquid. As described above, since the hydraulic shock absorber D1 of the present invention includes the pump P in addition to the electromagnetic pressure control valve EV, the generated force can be adjusted even at a low expansion and contraction speed, and the ride quality in the vehicle can be improved.

  Further, according to the hydraulic shock absorber D1 of the present invention, it can function not only as a passive shock absorber but also as an active actuator. Therefore, if the wheel falls into the hole while the vehicle is traveling, the wheel can contact the road surface by extending the hydraulic shock absorber D1, and if the wheel rides on an obstacle, the hydraulic shock absorber D1 is contracted. Then, since jumping up of the vehicle body can be suppressed, the wheels other than the wheels riding on the obstacle can come into contact with the road surface. As described above, according to the hydraulic shock absorber D1 of the present invention, it is possible to prevent the release of the ground contact load of the wheel, and the vehicle attitude is stabilized.

  Further, according to the hydraulic shock absorber D1 of the present invention, since the pump P is provided in addition to the electromagnetic pressure control valve EV, the pump functions as a shock absorber passively without using the pump P. It is also possible to adjust the force, and it is sufficient to use a small pump P and motor 4.

  In the case where the vibration of the vehicle body is sufficiently suppressed by the skyhook control, the expansion and contraction speed of the hydraulic pressure shock absorber D1 may be low, but in the hydraulic pressure shock absorber D1 of the present invention, the generated force is generated even when the expansion and contraction speed is low. Since the adjustment range of is secured, the damping effect of the vehicle body by skyhook control is high. In other words, since a large generated force can be generated even when the expansion and contraction speed of the hydraulic pressure shock absorber D1 is low, the skyhook damping coefficient can be set high to further enhance the damping effect of the vehicle body.

  Further, the hydraulic pressure shock absorber D1 of the present embodiment is provided with a controller C that controls the current supplied to the electromagnetic pressure control valve EV and the motor 4 based on the target pressures of the expansion side chamber R1 and the pressure side chamber R2. When the hydraulic shock absorber D1 is configured as described above, since the current command is obtained from the pressure command, it is not necessary to separately obtain control of the electromagnetic pressure regulating valve EV and the motor 4 from separate commands. You can control the power very easily.

  Furthermore, in the hydraulic shock absorber D1 of this example, the reservoir R, the base valve BV that allows only the flow of the liquid from the pressure side chamber R2 to the reservoir R and resists the flow of the liquid, and the pressure side chamber R2 from the reservoir R And a suction passage SP that allows only the flow of liquid toward the head. Thus, when the hydraulic shock absorber D1 is configured, the volume of the piston rod 3 when advancing and retracting into the cylinder 1 is compensated even in a single rod type shock absorber in which the piston rod 3 is inserted only into the expansion side chamber R1. At the same time, the generated force adjustment by the electromagnetic pressure control valve EV and the generated force adjustment by the pump P can be performed. When the hydraulic shock absorber D1 is configured as a so-called double rod type shock absorber in which the piston rod 3 is inserted not only into the expansion side chamber R1 but also into the pressure side chamber R2, the volume change due to the temperature change of the liquid is compensated The temperature compensating accumulator may be connected to the expansion side chamber R1 or the pressure side chamber R2, and in this case, the reservoir R, the discharge passage DP, the base valve BV, the suction passage SP and the check valve CV can be eliminated.

  Further, in the hydraulic shock absorber D1 of this example, the passage has the expansion side passage EP and the pressure side passage CP, and the electromagnetic pressure control valve EV is provided to the expansion side damping valve 10 provided in the expansion side passage EP The pressure-side damping valve 11 provided, a pilot passage 12 communicating the expansion side chamber R1 with the pressure side chamber R2, and the solenoid valve 13 provided in the pilot passage 12 are provided. The pressure upstream of the solenoid valve 13 in the pilot passage 12 is It is led as a pilot pressure that biases the expansion damping valve 10 and the compression damping valve 11 in the closing direction, and the pressure is adjusted by the solenoid valve 13 to adjust the opening pressure of the expansion damping valve 10 and the compression damping valve 11 It is configured to Thus, when the hydraulic shock absorber D1 is configured, it is not necessary to use two electromagnetic damping valves, an electromagnetic damping valve that controls a generation force at extension and a solenoid damping valve that controls a generation force at contraction. The generated force on both sides of the expansion and contraction can be controlled by the solenoid valve 13. Therefore, according to the hydraulic shock absorber D1 of this example, since the generated force on the extension side and the generated force on the contraction side can be controlled by the control of the solenoid valve 13 and the motor 4, the manufacturing cost can be reduced.

Second Embodiment
The hydraulic shock absorber D2 in the second embodiment is, as shown in FIG. 4, a cylinder 1, a piston 2 that divides the inside of the cylinder 1 into an expansion chamber R1 and a compression chamber R2, and a piston 2 in this example. A piston rod 3 which is movably inserted into the cylinder 1, an expansion side passage EP as a passage communicating the expansion side chamber R 1 and the pressure side chamber R 2, a pressure side passage CP, and an electromagnetic pressure control valve EV; A pump P1, a motor 4 for driving the pump P1, an accumulator ACC accumulated by the pump P1, a switch valve SV provided between the pump P1 and the accumulator ACC, an expansion side chamber R1 and a pressure side chamber R2, an electromagnetic pressure regulating valve EV, a switch valve SV, and a controller C for controlling the motor 4 are used, and are interposed between the sprung member and the unsprung member in a vehicle not shown It is.

  In this example, the pump P1 is a charge passage 30 that is downstream of the base valve BV of the discharge passage DP that connects the pressure side chamber R2 to the reservoir R and that connects the accumulator ACC with the upstream of the check valve CV of the suction passage SP. Provided in the middle of the Therefore, when driven by the motor 4, the pump P1 sucks the liquid from the reservoir R and supplies the liquid to the accumulator ACC so that the accumulator ACC can accumulate pressure. The pump passage 22 provided in the hydraulic shock absorber D1 of the first embodiment is abolished in this example.

  The switching valve SV is an electromagnetic directional switching valve, and is switch-controlled by the controller C. The switching valve SV takes the pressure side communication position, the extension side communication position, and the blocking position depending on the energization state of the switching valve SV from the controller C to the solenoid. Specifically, the switching valve SV communicates the supply port Po to the control port A in communication with the pressure side chamber R2 and communicates the discharge port T to the control port B in communication with the expansion side chamber R1; One of a blocking position in which neither the supply port Po nor the discharge port T communicate with any of the control ports A and B, and the extension side communication position in which the supply port Po communicates with the control port B and the discharge port T communicates with the control port A It is supposed to take one. The control port A is in communication with the pressure side chamber R2 through the passage 33, and the control port B is in communication with the expansion side chamber R1 through the passage 34.

  The pump P1 of the charge passage 30 and the accumulator ACC are in communication with the supply port Po of the switching valve SV via the supply passage 31. Further, the discharge port T is in communication with the discharge passage T at a position downstream of the base valve BV of the discharge passage DP communicating the pressure side chamber R2 with the reservoir R and above the check valve CV of the suction passage SP.

  Therefore, when the switching valve SV takes the pressure side communication position, the liquid is supplied from the inside of the accumulator ACC to the pressure side chamber R2, and the extension side chamber R1 is in communication with the reservoir R. In this situation, when the pump P1 is driven by the motor 4, the liquid discharged by the pump P1 is also supplied to the pressure side chamber R2. As described above, when the fluid is supplied to the pressure chamber R2 from the accumulator ACC and / or the pump P1, the hydraulic shock absorber D2 is extended and the fluid discharged from the expansion chamber R1 to be compressed is stored in the reservoir R. Absorbed by

  On the other hand, when the switching valve SV takes the extension side communication position, the liquid is supplied from the inside of the accumulator ACC to the extension side chamber R1, and the pressure side chamber R2 is in communication with the reservoir R. In this situation, when the pump P1 is driven by the motor 4, the liquid discharged by the pump P1 is also supplied to the expansion chamber R1. As described above, when the fluid is supplied to the expansion chamber R1 from the accumulator ACC and / or the pump P1, the hydraulic shock absorber D2 is contracted and the fluid discharged from the compression chamber R2 to be compressed is stored in the reservoir R. Absorbed by

  In addition, when the switching valve SV takes the shutoff position, the pump P1 and the accumulator ACC are not communicated to the expansion side chamber R1 nor to the pressure side chamber R2, and are shut off. Can be supplied to the accumulator ACC to accumulate pressure in the accumulator ACC.

  Even in the hydraulic shock absorber D2 of this example, when the switching valve SV takes the shutoff position, the differential pressure between the expansion side chamber R1 and the pressure side chamber R2 can be controlled by the electromagnetic pressure adjusting valve EV, so the first embodiment The adjustment can be made in the range from line G1 to line G2 and in the range from line G3 to line G4 in the first quadrant and the third quadrant in FIG.

  When the fluid is supplied from the pump P1 to the extension chamber R1 with the switching valve SV in the extension side communication position, the fluid is discharged from the pressure chamber R2 to the reservoir R. It functions as an actuator. And, even in this hydraulic shock absorber D2, since the pressure of the expansion chamber R1 can be controlled by the discharge pressure of the pump P1, generated force on the contraction side of the hydraulic shock absorber D2 according to the amount of current supplied to the motor 4 Control. The valve opening pressure of the expansion damping valve 10 may be set higher than the pressure of the expansion chamber R1 controlled by the pump P1. Since the discharge flow rate of the pump P1 is limited, when the hydraulic shock absorber D2 functions as an actuator and contracts, it is within the range surrounded by the X axis, Y axis, line A1 and line A2 of the second quadrant in FIG. Can generate the Line A1 shows the limit by the set pressure of expansion side damping valve 10, and line A2 shows the limit which can not generate power by the flow rate limit of pump P1.

  Furthermore, when the fluid is supplied from the pump P1 to the pressure side chamber R2 with the switch valve SV at the pressure side communication position, the liquid is discharged to the reservoir R from the expansion side chamber R1. Function as an actuator. And, even in this hydraulic shock absorber D2, since the pressure of the pressure side chamber R2 can be controlled by the discharge pressure of the pump P1, generated force on the extension side of the hydraulic shock absorber D2 according to the amount of current supplied to the motor 4 Control. The valve opening pressure of the pressure side damping valve 11 may be made higher than the pressure of the pressure side chamber R2 controlled by the pump P1. Since the discharge flow rate of the pump P1 is limited, when the hydraulic shock absorber D2 functions as an actuator and contracts, it is within the range enclosed by the X axis, Y axis, line A3 and line A4 of the fourth quadrant in FIG. Can generate the Line A3 shows the limit by the set pressure of pressure side damping valve 11, and line A4 shows the limit which can not generate power by the flow rate limit of pump P1.

  Further, when the hydraulic shock absorber D2 is expanded and contracted by an external force, if the pump P1 is driven, the liquid can be sent to the expansion side chamber R1 or the pressure side chamber R2, so that the hydraulic pressure of the first embodiment As in the case of the shock absorber D1, the generated force can be output also in the above-mentioned regions Z1 and Z2. Also, with regard to the pressure override characteristic that appears because the expansion damping valve 10 and the compression damping valve 11 give resistance to the flow of liquid, the pump P1 and the motor 4 are used as a generator when the hydraulic shock absorber D2 is stretched by an external force. The override component can be cut by using the switching valve SV in the reverse flow direction as the pressure side or the extension side communication position so that it can be used. In the hydraulic shock absorber D2 of this example, since the liquid can also be reversely flowed to the accumulator ACC, the response of the override removal becomes faster than the hydraulic shock absorber D1.

  As described above, the switching valve SV communicates the pump P1 and the accumulator ACC to the expansion chamber R1 or the compression chamber R2 when generating the generated force in the regions Z1 and Z3 when the hydraulic shock absorber D2 functions as an actuator. , I can think of when to cut the override part. When the vertical speed of the vehicle body, which is mainly a sprung member, is switched, etc., the switching valve SV is in the blocking position, and the pressure in the expansion side chamber R1 or the pressure side chamber R2 is supplied with the liquid from the pump P1. In some cases, the expansion damping valve 10 or the compression damping valve 11 is opened to adjust the pressure difference between the expansion chamber R1 and the compression chamber R2.

  By the way, in this example, the accumulator ACC is provided separately from the pump P1. If the accumulator ACC is pre-stored by the pump P1, the liquid can be instantaneously supplied to the expansion chamber R1 or the compression chamber R2 when the switching valve SV switches from the blocking position to the expansion communication position or the pressure communication position. Since the pump P1 and the motor 4 have inertia, the response of the discharge pressure of the pump P1 to the change of the amount of current supplied to the motor 4 takes some time. According to the present invention, since the accumulator ACC is provided, if the necessary pressure is accumulated in advance in the accumulator ACC and the liquid is supplied from the accumulator ACC into the cylinder 1, even if there is a response delay of the discharge pressure of the pump P1. The pressure of the expansion side chamber R1 or the pressure side chamber R2 can be controlled to a target pressure.

  The controller C performs torque control for the pump P in order to perform skyhook control, and the target torque is proportional to the absolute value of the vertical velocity of the vehicle body multiplied by the skyhook damping coefficient. Therefore, as for the driving and the braking (braking) of the pump P, as in the first embodiment, a dedicated microcomputer may be provided in the controller C and the current may be controlled by torque control. Further, the internal pressure of the accumulator ACC is proportional to the torque of the motor 4 that drives the pump P1. Therefore, the torque of the motor 4 and the internal pressure of the accumulator ACC depend on the speed of the vehicle in the vertical direction, and both the torque and the internal pressure increase when the movement of the vehicle becomes fast, and the torque and the internal pressure also increase when the movement of the vehicle is slow. Decrease. When the internal pressure of the accumulator ACC is increased, the motor 4 is driven. When the internal pressure of the accumulator ACC is reduced, the motor 4 can be regenerated by driving the motor 4 with the flow of liquid discharged from the accumulator ACC. The controller C switches between the expansion communication position and the pressure communication position depending on the direction of the vertical velocity of the vehicle body in order to perform skyhook control for the switching valve SV. With such control, it is possible to realize skyhook control by causing the pump P1 and the switching valve SV to function as the pump P in the hydraulic pressure damper D1.

  Then, in the hydraulic shock absorber D2 of this example, even if the movement of the vehicle body is switched to a sudden decrease, the direction of the force exerted by the hydraulic shock absorber D2 can be switched at the speed to switch the position of the switching valve SV. The response speed for switching of the direction of force can be improved compared to the shock absorber D1. Further, in the hydraulic shock absorber D2 of the present example, when the direction of movement of the vehicle body changes rapidly without switching, the fluid can be supplied from the accumulator ACC to the cylinder 1, so the hydraulic shock absorber D2 is higher than the hydraulic shock absorber D1. The force exerted by the hydraulic shock absorber D2 can be changed in response.

  Thus, the hydraulic shock absorber D2 can communicate the accumulator ACC accumulated by the pump P1, the pump P1 and the accumulator ACC with one of the expansion side chamber R1 and the pressure side chamber R2, and can communicate with the pump P1 and the accumulator It is configured to include an expansion side chamber R1 and a switching valve SV that can shut off the ACC from the pressure side chamber R2. Thus, when the hydraulic shock absorber D2 is configured, the response delay due to the inertia of the pump P1 and the motor 4 for driving the pump P1 can be eliminated, and the differential pressure between the expansion side chamber R1 and the pressure side chamber R2 can be controlled as aimed. Since generation | occurrence | production of the driving | running | working initial stage of pump P1 does not produce a fall, the grounding load can be stabilized more and the ride in a vehicle can be improved further.

  This completes the description of the embodiments of the present invention, but it is to be understood that the scope of the present invention is not limited to the exact details shown or described.

DESCRIPTION OF SYMBOLS 1 ... Cylinder 2, 2 ... Piston, 4 ... Motor 10: Expansion side damping valve 11 Pressure side damping valve 12 Pilot passage ACC: Accumulator BV ···· · · · Base valve, C · · · Controller · CP · · · · pressure side passage (passage), D1, D2 · · · hydraulic shock absorber, EP · · · expansion side passage (passage), EV · · · electromagnetic pressure adjustment Valve, P, P1: pump, R: reservoir, R1: extension side chamber, R2: pressure side chamber, SP: suction passage, SV: switching valve,

Claims (8)

With the cylinder,
A piston which divides the inside of the cylinder into an expansion side chamber and a compression side chamber;
A passage communicating the expansion side chamber with the pressure side chamber;
An electromagnetic pressure control valve which is provided in the passage and is capable of adjusting the valve opening pressure by adjusting the pressure in the pilot passage which connects the expansion side chamber and the pressure side chamber;
With the pump,
A motor for driving the pump;
A hydraulic shock absorber characterized in that it is possible to supply liquid discharged by the pump by selecting one of the expansion side chamber and the pressure side chamber. An accumulator accumulated by the pump;
The pump and the accumulator can be selectively communicated with one of the expansion side chamber and the pressure side chamber, and the pump and the accumulator can be separated from the expansion side chamber and the pressure side chamber. A hydraulic shock absorber according to claim 1, characterized in. The controller according to claim 1 or 2, further comprising: a controller that controls a current supplied to the electromagnetic pressure control valve and the motor based on a pressure command that indicates a differential pressure between the expansion side chamber and the pressure side chamber. Hydraulic shock absorber. A reservoir,
A base valve that allows only the flow of liquid from the pressure side chamber to the reservoir and resists the flow of liquid;
The hydraulic shock absorber according to any one of claims 1 to 3, further comprising: a suction passage that allows only the flow of liquid from the reservoir to the pressure side chamber. Interposed between the sprung member and the unsprung member in the vehicle,
The hydraulic shock absorber according to claim 1, characterized in that the motor generates torque proportional to the vertical velocity of the sprung member. Interposed between the sprung member and the unsprung member in the vehicle,
The motor is controlled to generate a torque that is proportional to the absolute value of the vertical velocity of the sprung member;
The hydraulic shock absorber according to claim 2, wherein the switching valve is switch-controlled by the direction of the vertical velocity of the sprung member. The passage has an expansion side passage and a pressure side passage,
The electromagnetic pressure control valve is
An expansion side damping valve provided in the expansion side passage;
A compression side damping valve provided in the compression side passage;
A pilot passage communicating the expansion side chamber with the pressure side chamber;
A solenoid valve provided in the pilot passage;
The pressure upstream of the solenoid valve in the pilot passage is derived as a pilot pressure that biases the expansion damping valve and the compression damping valve in the closing direction,
The hydraulic shock absorber according to any one of claims 1 to 6, wherein the pilot pressure is adjusted by the solenoid valve to adjust the opening pressure of the expansion damping valve and the compression damping valve. . The opening pressure of the expansion damping valve and the compression damping valve is set to increase as the amount of current supplied to the solenoid valve increases.
The hydraulic shock absorber according to claim 7, wherein when the direction of expansion and contraction and the direction of force to be generated are the same, the target current indicating the amount of current of the solenoid valve is maximized.

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