JP6607022B2 - Damping force adjustment mechanism - Google Patents

Description

  The present invention relates to a damping force adjusting mechanism, and more particularly to a damping force adjusting mechanism suitable for a shock absorber of an automobile.

  Some shock absorbers mounted on vehicles have a damping force adjusting mechanism. This mechanism can adjust the damping force generated by the piston because the damping force is determined uniquely with respect to the operating speed of the piston, and it is impossible to satisfy the contradictory riding comfort and steering stability. Various types are known. For example, in the following Patent Document 1, for the purpose of “providing a damping force adjusting shock absorber capable of generating a stable damping force even when an actuator fails”, “a cylinder in which a fluid is sealed, A piston slidably provided in the cylinder; a piston rod connected to the piston and extending outward from the cylinder; and a passage in which fluid flows by sliding of the piston in the cylinder; A pilot-type damping valve that controls a flow of oil and fluid in the passage to generate a damping force and adjusts a valve opening pressure by using a part of the fluid flow as a pilot pressure; and a part of the fluid flow And a damping force adjusting buffer that adjusts the damping force by adjusting the pilot pressure and an actuator that operates the damping force adjusting valve. The damping force adjusting valve restricts the flow of fluid when the actuator fails, a relief valve is provided in parallel with the damping force adjusting valve, and a sub-flow that controls the flow of fluid downstream of the relief valve. A damping force adjusting type shock absorber provided with a damping valve has been proposed (described in paragraphs [0010] and [0011] of Patent Document 2).

Japanese Patent No. 4985984

  The damping force adjustment type shock absorber described in Patent Document 1 includes a pilot type damping valve and a damping force adjustment valve, and is configured to be able to perform pilot pressure control with respect to bidirectional fluid flow in the extending direction and the contracting direction. However, the number of parts is large, the structure becomes large with a complicated structure, and this increases the cost. Further, it is not possible to adjust to different damping force characteristics with respect to the fluid flow in the extension direction and the contraction direction.

  Accordingly, an object of the present invention is to provide a damping force adjusting mechanism that can secure a desired damping force characteristic by pilot pressure control with respect to a bidirectional fluid flow with a simple configuration.

  To achieve the above object, the present invention provides a case for containing a working fluid, a seal member that separates the inside of the case into a first fluid chamber and a second fluid chamber, and the case that holds the seal member and holds the case. A damping force adjusting mechanism that controls the pressure of the working fluid and adjusts the damping force of the working fluid pressure receiving portion in the housing, and is housed in the housing, and the first fluid chamber And a damping valve that controls opening and closing between the second fluid chamber and the second fluid chamber. The damping valve is fluidly coupled to the pilot chamber via the pilot chamber, and the damping valve is opened according to the pressure control of the fluid in the pilot chamber. A control valve that controls the valve pressure; an actuator that electrically drives and controls the control valve; a switching valve that is movably accommodated in the housing and disposed so as to contact the damping valve; and the switching valve Between the valve and the damping valve A valve chamber that communicates with the pilot chamber through an orifice formed in the damping valve, and is normally in communication with the first fluid chamber, and the pressure of the fluid in the second fluid chamber is the first chamber. When the pressure of the fluid in one fluid chamber becomes larger than the pressure of the fluid, the switching valve is moved so that the communication with the first fluid chamber is blocked, and the valve chamber is connected to the first chamber via the pilot chamber. A first communication path that communicates with the first fluid chamber, a second communication path that communicates the valve chamber with the second fluid chamber via the pilot chamber, and a first communication path that communicates with the second fluid chamber. And a first check valve that allows the flow of fluid in the direction of the first fluid chamber and prevents a reverse flow, and the second fluid chamber. A second check valve that permits fluid flow in the direction and prevents flow in the reverse direction, wherein the switching valve includes the second check valve. A configuration is provided that includes a valve mechanism that allows a flow of fluid to the valve chamber and prevents a reverse flow when the pressure of the fluid in the fluid chamber exceeds a predetermined pressure by a pressure of the fluid in the valve chamber. Is.

  In the above damping force adjusting mechanism, the switching valve has a pressure receiving area larger than the pressure receiving area of the damping valve, and when the fluid flows into the valve chamber from the first fluid chamber, the pressure receiving pressure of the damping valve The damping force characteristic is adjusted based on the differential pressure between the fluid pressure corresponding to the area and the fluid pressure in the pilot chamber, and the communication between the first fluid chamber and the valve chamber is cut off by moving the switching valve. In some cases, the damping force characteristic may be adjusted based on the differential pressure between the fluid pressure corresponding to the pressure receiving area of the switching valve and the fluid pressure in the pilot chamber.

  Alternatively, the switching valve is disposed so as to be able to contact the damping valve, and has a contact portion that has a flow area smaller than a flow area of the orifice of the attenuation valve when the switching valve contacts the attenuation valve. It is good.

  In the above-described damping force adjusting mechanism, the case is configured by a cylindrical body that accommodates a working fluid, and the housing and the seal member each slide in the cylindrical body and serve as the first fluid chamber in the cylindrical body. It consists of a piston that is separated into an upper chamber and a lower chamber that is the second fluid chamber, and a seal member attached to the piston, and controls the working fluid that flows through the piston in the cylinder to adjust the damping force Can be configured to.

  Since this invention is comprised as mentioned above, there exist the following effects. That is, the damping force adjusting mechanism of the present invention is housed in the housing, and controls the opening and closing between the first fluid chamber and the second fluid chamber. And a control valve for controlling the valve opening pressure of the damping valve according to the pressure control of the fluid in the pilot chamber, an actuator for electrically driving and controlling the control valve, and a damping valve movably accommodated in the housing A switching valve that is arranged so as to be able to contact the valve, and a valve chamber that is formed between the switching valve and the damping valve and communicates with the pilot chamber via an orifice formed in the damping valve. A valve that communicates with the fluid chamber, and when the pressure of the fluid in the second fluid chamber becomes greater than the pressure of the fluid in the first fluid chamber, the switching valve moves to cut off the communication with the first fluid chamber. The chamber and the valve chamber communicate with the first fluid chamber via the pilot chamber A first communication path, a second communication path that communicates the valve chamber with the second fluid chamber via the pilot chamber, and a first communication path that are disposed in the direction of the first fluid chamber. A first check valve that allows fluid flow and blocks reverse flow, and a second communication passage, allows fluid flow toward the second fluid chamber and allows reverse flow. A second check valve for preventing the fluid from flowing into the valve chamber when the pressure of the fluid in the second fluid chamber exceeds the pressure of the fluid in the valve chamber by a predetermined pressure or more. It is configured to have a valve mechanism that allows and prevents reverse flow, and a simple one-way fluid control valve mechanism having a single damping valve is provided with a switching valve and two check valves. With the configuration, the variable width can be set wide by pilot pressure control for bidirectional fluid flow, ensuring the desired damping force characteristics It is possible.

  In the above damping force adjusting mechanism, the switching valve has a pressure receiving area larger than the pressure receiving area of the damping valve, and when the fluid flows from the first fluid chamber into the valve chamber, the fluid corresponding to the pressure receiving area of the damping valve When the switching valve moves and the communication between the first fluid chamber and the valve chamber is blocked by adjusting the damping force characteristics based on the pressure difference between the pressure and the fluid pressure in the pilot chamber, the pressure response area depends on the pressure receiving area of the switching valve. If the damping force characteristic is adjusted based on the differential pressure between the fluid pressure and the fluid pressure in the pilot chamber, for example, the damping force characteristic can be adjusted differently when the housing is raised and lowered. .

  Alternatively, the above switching valve is arranged so as to be able to contact the damping valve, and when it contacts the damping valve, it has a contact portion that has a flow area smaller than the flow area of the orifice of the attenuation valve. It is possible to adjust the damping force characteristics to be different when the housing is raised and lowered.

  In the above-described damping force adjusting mechanism, the case is configured by a cylindrical body that contains a working fluid, and the housing and the seal member slide in the cylindrical body, and the upper chamber that is the first fluid chamber in the cylindrical body. And a piston that is separated into a lower chamber that is a second fluid chamber, and a seal member that is attached to the piston, and controls the working fluid that flows through the piston in the cylinder to adjust the damping force. It is possible to provide a damping force adjusting mechanism suitable for an automobile shock absorber.

It is sectional drawing of the damping-force adjustment mechanism which concerns on one Embodiment of this invention. It is sectional drawing which shows the expansion operation state of the damping-force adjustment mechanism which concerns on one Embodiment of this invention. It is sectional drawing which shows the contraction operation state of the damping force adjustment mechanism which concerns on one Embodiment of this invention. It is sectional drawing of the damping force adjustment mechanism which concerns on other embodiment of this invention. It is sectional drawing which shows the expansion operation state of the damping force adjustment mechanism which concerns on other embodiment of this invention. It is sectional drawing which shows the contraction operation state of the damping force adjustment mechanism which concerns on other embodiment of this invention. It is sectional drawing which shows another aspect of the switching valve and damping valve with which it uses for the damping-force adjustment mechanism which concerns on other embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a damping force adjusting mechanism according to an embodiment of the present invention, and is used for, for example, a shock absorber of an automobile. In the present embodiment, the housing 3 (corresponding to the piston of the shock absorber) of the working fluid pressure receiving part is accommodated in the case 1 (corresponding to the cylinder of the shock absorber) containing the working fluid via the seal member 2, 2, the inside of the case 1 is separated into a first fluid chamber UC (corresponding to the upper chamber of the shock absorber) and a second fluid chamber LC (corresponding to the lower chamber of the shock absorber). 6 and the rod 7 are joined. The housing 3 accommodates a damping valve 4 that controls opening and closing between the first fluid chamber UC and the second fluid chamber LC. Further, a control valve 5 that is fluidly coupled to the damping valve 4 via the pilot chamber CP and controls the valve opening pressure of the damping valve 4 in accordance with the pressure control of the fluid in the pilot chamber CP is provided. An actuator 6 for electrically driving and controlling this is provided. That is, the control valve 5 is electrically driven and controlled by the actuator 6 so that the fluid pressure in the pilot chamber CP is controlled. A seal member 2 shown in FIG. 1 represents a labyrinth portion formed on the piston.

  The switching valve 8 is movably accommodated in the housing 3 and disposed so as to be able to contact the damping valve 4. A valve chamber VC is formed between the switching valve 8 and the damping valve 4. This valve chamber VC communicates with the pilot chamber CP through an orifice OR formed in the damping valve 4 and always communicates with the first fluid chamber UC (via the communication path P3) to provide the second fluid. When the pressure of the fluid in the chamber LC becomes larger than the pressure of the fluid in the first fluid chamber UC, the switching valve 8 is moved so that the communication with the first fluid chamber UC is blocked. Yes.

  Further, in the housing 3, the first communication passage P <b> 1 that communicates the valve chamber VC with the first fluid chamber UC through the pilot chamber CP, and similarly the valve chamber VC communicates with the second fluid chamber LC. A second communication path P2 is formed. A first check valve 91 that allows a fluid flow in the direction of the first fluid chamber UC and prevents a reverse flow is interposed in the first communication passage P1, and the second communication passage P2 includes a first check valve 91. Is provided with a second check valve 92 that allows the flow of fluid in the direction of the second fluid chamber LC and blocks the flow in the reverse direction. That is, when the fluid introduced into the housing 3 is discharged, the first check valve 91 or the second check valve 92 is set to open.

  In the present embodiment, an annular valve seat portion 3a is formed in the housing 3, the damping valve 4 is formed in a cup shape of a bottomed cylindrical body, and the bottom surface of the valve seat portion 3a is in contact with the seat. In order to obtain, it is accommodated in the housing 3 and slidably supported at a predetermined axial distance. A damping valve spring 41 of a compression coil spring is accommodated in the housing 3 and is stretched between a bottom portion of the damping valve 4 and a valve seat member 52 described later. The housing 3 is composed of a plurality of members so as to form the chambers and the communication passages. However, in FIG. 1, the whole is represented by a single symbol for ease of explanation.

  The control valve 5 according to the present embodiment includes a valve body 51 and a cup-shaped valve seat member 52 supported by the housing 3 so as to abut against the valve body 51. A return spring 53 is interposed between the valve body 51 and the valve seat member 52 and biases the valve body 51 and the valve seat member 52 so as to expand them. A communication hole 54 communicating with the valve chamber VC is formed at the bottom of the valve seat member 52, and the actuator 6 is controlled so that the tip of the valve body 51 is closely spaced from the communication hole 54. The actuator 6 has a general configuration including a linear solenoid (not shown) mounted on the housing 3 and a plunger (not shown) that drives the valve body 51 in response to excitation of the linear solenoid. Since there is, description is abbreviate | omitted.

  The switching valve 8 of the present embodiment has a pressure receiving area larger than the pressure receiving area of the damping valve 4, and when the fluid flows into the valve chamber VC from the first fluid chamber UC, the pressure receiving area of the damping valve 8 is increased. The damping force characteristic (pressure-flow rate characteristic) based on the differential pressure between the corresponding fluid pressure and the fluid pressure in the pilot chamber CP is adjusted, and the switching valve 8 moves to change between the first fluid chamber UC and the valve chamber VC. When the communication is cut off, the damping force characteristic (pressure-flow rate characteristic) is adjusted based on the pressure difference between the fluid pressure corresponding to the pressure receiving area of the switching valve 8 and the fluid pressure in the pilot chamber CP. .

  As shown in FIG. 1, the switching valve 8 includes a valve mechanism including a ball valve 81 and a relief pull 82, and the pressure of the fluid in the second fluid chamber LC is set to a predetermined pressure (relief) from the pressure of the fluid in the valve chamber VC. It is configured to allow the flow of the fluid to the valve chamber VC and prevent the flow in the reverse direction when the pressure becomes larger than (set by the biasing force of the pulling 82). Thus, according to the flow of fluid from the first fluid chamber UC side introduced into the housing 3 (FIG. 2) and the flow of fluid from the second fluid chamber LC side (FIG. 3), the former A characteristic in which the damping force characteristic and the latter damping force characteristic are different, that is, the latter (the operation shown in FIG. 3) is opened with a lower pressure difference than the former (the operation shown in FIG. 2), so that a gentle pressure-flow rate characteristic is obtained. Is set to

  The operation of the damping force adjusting mechanism configured as described above will be described. When, for example, the rod 7 is lifted upward in FIG. 1 from the solenoid excitation state of the actuator 6 shown in FIG. 1 (for example, the buffer is extended), the housing 3 starts to compress in the first fluid chamber UC. The fluid in the fluid chamber UC is introduced into the valve chamber VC via the communication path P3, and as shown by a thin line arrow (f1) in FIG. 2, the orifice OR, the pilot chamber CP, the communication hole 54, and the periphery of the valve body 51 , The second communication passage P2 and the second check valve 92 to be discharged to the second fluid chamber LC side. In FIG. 2 (and FIG. 3), since the leader line intersects with the arrow indicating the flow of the fluid, a part of the reference numerals shown in FIG. 1 is omitted. Moreover, the arrow which shows the flow of a fluid shows only a representative example, and the arrow which shows the same flow (on the left and right of FIG. 2) is omitted.

  When the flow rate of the fluid introduced into the housing 3 from the first fluid chamber UC side increases as the rod 7 (and thus the housing 3) rises, the pressure difference between the fluids applied to both surfaces of the bottom of the damping valve 4 Accordingly, the damping valve 4 is separated from the valve seat portion 3a against the urging force of the damping valve spring 41, and the fluid flows from the gap between them to the second fluid as shown by a thick arrow (Fe) in FIG. It is discharged to the chamber LC side. At this time, since the control valve 5 is driven by the actuator 6 and the fluid pressure in the pilot chamber CP is controlled, the valve opening pressure of the damping valve 4 is variably controlled to obtain a desired damping force characteristic (pressure-flow rate characteristic). Adjusted.

  On the other hand, when the rod 7 is pulled downward in FIG. 1 (for example, the shock absorber is contracted) and the housing 3 starts to compress the second fluid chamber LC, first, the ball valve 81 of the switching valve 8 is relieved. The valve is opened against the urging force of the pulling 82, and as shown by a thin arrow (f2) in FIG. 3, the orifice OR, the pilot chamber CP, the communication hole 54, the gap around the valve body 51, the first communication path P1. And, it is discharged to the first fluid chamber UC side through the first check valve 91.

  When the flow rate of the fluid introduced into the housing 3 from the second fluid chamber LC side increases as the descending speed of the rod 7 (housing 3) increases, the pressure difference between the fluids applied to both surfaces of the bottom of the damping valve 4 The damping valve 4 is separated from the valve seat portion 3a against the urging force of the damping valve spring 41, and as shown by a thick arrow (Fs) in FIG. It is discharged to the UC side. Also in this case, since the control valve 5 is driven by the actuator 6 to control the pressure in the pilot chamber CP2, the valve opening pressure of the damping valve 4 is variably controlled, and what is the damping force characteristic when the housing 3 is raised? Adjust to different (desired) pressure-flow characteristics.

  4 to 6 show a damping force adjusting mechanism according to another embodiment of the present invention. In this embodiment, the switching valve 8x is disposed so as to be able to contact the damping valve 4, and the damping valve 4 When the abutment portion 8 abuts, the contact portion 8 a having a flow area smaller than the flow area of the orifice OR of the damping valve 4 is provided. As shown in FIG. 6, the abutting portion 8a is integrally formed as a standing wall portion surrounding the orifice OR of the damping valve 4 and having a communication passage 8b having a flow passage area smaller than the flow passage area of the orifice OR. The front end surface is disposed so as to be able to contact the damping valve 4. In addition, as shown in FIG. 7, the contact portion 8a of the switching valve 8x is formed in a conical shape so that the tip portion thereof can enter the orifice OR of the damping valve 4, and the orifice of the damping valve 4 A slit ORs may be formed in the OR, and the flow path area of only the slit ORs may be formed when the outer peripheral surface of the contact portion 8a contacts the inner peripheral surface of the orifice OR.

  Further, the switching valve 8x is provided with a communication passage 8c as shown in FIGS. 4 to 7, and is provided with a check valve 8y functioning as the valve mechanism described above, and the second passage through the communication passage 8c. The fluid flow from the fluid chamber LC side to the first fluid chamber UC side (from the lower side to the upper side in FIG. 4) is allowed and the flow in the reverse direction is prevented. Since other configurations are the same as those of the above-described embodiment, substantially the same members are denoted by the same reference numerals and description thereof is omitted.

  Thus, in the present embodiment, as shown in FIG. 5, when the rod 7 is lifted upward (the shock absorber is extended) and the housing 3 starts to compress in the first fluid chamber UC, The fluid in the fluid chamber UC is introduced into the valve chamber VC through the communication path P3, and as shown by a thin line arrow (f1) in FIG. 5, the orifice OR, the pilot chamber CP, the communication hole 54, the periphery of the valve body 51 , The second communication passage P2 and the second check valve 92 to be discharged to the second fluid chamber LC side. Also in FIG. 5 (and FIG. 6), since the leader line intersects with the arrow indicating the flow of the fluid, a part of the reference numerals shown in FIG. 4 is omitted. Moreover, the arrow which shows the flow of a fluid shows only a representative example, and the arrow which shows the same flow (on the right and left of FIG. 5 (and FIG. 6)) is abbreviate | omitted.

  On the other hand, when the rod 7 is pulled down (shrinker operation of the shock absorber) and the housing 3 starts to compress the second fluid chamber LC, the tip surface of the contact portion 8a of the switching valve 8x as shown in FIG. Is in contact with the bottom surface of the damping valve 4, but the fluid in the second fluid chamber LC is connected to the communication path 8c, the check valve 8y, and the communication path 8b of the switching valve 8x as shown by a thin line arrow (f2) in FIG. , The orifice OR, the pilot chamber CP, the communication hole 54, the gap around the valve body 51, the first communication passage P1, and the first check valve 91 are discharged to the first fluid chamber UC side. Thus, when the extension operation is started when the rod 7 is pulled upward and when the contraction operation is started when the rod 7 is lowered downward, the pressure-flow rate characteristics are different as described above, and the initial characteristics suitable for each operation can be set. it can. The same applies to the embodiment using the switching valve 8x shown in FIG.

  Subsequent operations accompanying the increase in the speed of the rod 7 are the same as in the above-described embodiment. That is, when the flow rate of the fluid introduced into the housing 3 from the first fluid chamber UC side increases, the damping valve 4 causes the damping valve spring 41 to move due to the pressure difference between the fluids applied to both sides of the bottom of the damping valve 4. As shown by a thick arrow (Fe) in FIG. 5, the fluid is discharged to the second fluid chamber LC side from the valve seat 3 a against the urging force, as indicated by a thick arrow (Fe) in FIG. 5. At this time, since the control valve 5 is driven by the actuator 6 and the pressure in the pilot chamber CP is controlled, the valve opening pressure of the damping valve 4 is variably controlled. On the other hand, when the flow rate of the fluid introduced into the housing 3 from the second fluid chamber LC side increases, the damping valve 4 causes the damping valve spring 41 to move due to the pressure difference between the fluids applied to both sides of the bottom of the damping valve 4. As shown by a thick arrow (Fs) in FIG. 6, the fluid is discharged to the first fluid chamber UC side from the valve seat portion 3a against the biasing force. Further, since the control valve 5 is driven by the actuator 6 to control the pressure in the pilot chamber CP, the valve opening pressure of the damping valve 4 is variably controlled.

  In each of the above-described embodiments, the case 1 is configured by a shock absorber cylinder that accommodates the working fluid, and the housing 3 and the seal member 2 slide in the cylinder and the first fluid chamber in the cylinder. A piston that is separated into a UC (upper chamber) and a second fluid chamber LC (lower chamber) and a seal member attached to the piston, and controls the working fluid that flows through the piston in the cylinder to control the damping force. Is a damping force adjustment mechanism suitable for a shock absorber, but is not limited to a shock absorber, and is not limited to an automobile, but can be applied to various dampers, separate pressure devices, etc. Can do. In each of the above embodiments, the so-called one-way fluid control valve mechanism having the single damping valve 4 is provided with the switching valve 8 (or 8x) and the first and second check valves 91 and 92. However, it is not limited to the one-way fluid control valve mechanism shown in FIG. 1 or FIG. 4, and the switching valve 8 (8x) may be different.

DESCRIPTION OF SYMBOLS 1 Case 2 Seal member 3 Housing 4 Damping valve 5 Control valve 6 Actuator 7 Rod 8, 8x Switching valve 41 Damping valve spring 51 Valve body 52 Valve seat member 53 Return spring 54 Communication hole 91 1st check valve 92 2nd Check valve P1 First communication path P2 Second communication path CP Pilot chamber OR Orifice UC First fluid chamber LC Second fluid chamber

Claims (4)

  A case that contains a working fluid; a seal member that separates the inside of the case into a first fluid chamber and a second fluid chamber; and a housing that holds the seal member and accommodates it in the case. A damping force adjusting mechanism that controls the pressure of the working fluid and adjusts the damping force of the working fluid pressure receiving portion, and is housed in the housing, and between the first fluid chamber and the second fluid chamber. A damping valve that controls opening and closing, a control valve that is fluidly coupled to the damping valve via a pilot chamber, and that controls a valve opening pressure of the damping valve in accordance with pressure control of the fluid in the pilot chamber; and the control valve An actuator for electrically driving and controlling, a switching valve that is movably accommodated in the housing and is disposed so as to contact the damping valve, and is formed between the switching valve and the damping valve, Orif formed on the damping valve A valve chamber that communicates with the pilot chamber via a fluid, and is normally communicated with the first fluid chamber, and the pressure of the fluid in the second fluid chamber is greater than the pressure of the fluid in the first fluid chamber. A valve chamber in which communication with the first fluid chamber is cut off when the switching valve moves and the valve chamber communicates with the first fluid chamber via the pilot chamber. A first communication path, a second communication path communicating the valve chamber with the second fluid chamber via the pilot chamber, and the first fluid chamber. A first check valve that permits fluid flow in the direction and prevents reverse flow, and the second communication passage, and allows fluid flow in the direction of the second fluid chamber. A second check valve for blocking a reverse flow, wherein the switching valve is configured so that the pressure of the fluid in the second fluid chamber is within the valve chamber. Damping force adjustment mechanism, characterized in that it comprises a valve mechanism for preventing the reverse flow to allow the flow of fluid into the valve chamber when a large predetermined pressure or higher than the pressure of the body.   The switching valve has a pressure receiving area larger than the pressure receiving area of the damping valve, and when fluid flows into the valve chamber from the first fluid chamber, a fluid pressure corresponding to the pressure receiving area of the damping valve and the pressure The pressure-receiving area of the switching valve is adjusted when the switching valve moves and the communication between the first fluid chamber and the valve chamber is shut off by adjusting the damping force characteristic based on the differential pressure with the fluid pressure in the pilot chamber. The damping force adjusting mechanism according to claim 1, wherein the damping force adjusting mechanism is adjusted to a damping force characteristic based on a differential pressure between a fluid pressure according to the pressure and a fluid pressure in the pilot chamber.   The switching valve is disposed so as to be able to contact the damping valve, and has a contact portion having a flow area smaller than a flow area of the orifice of the attenuation valve when the switching valve is in contact with the attenuation valve. The damping force adjusting mechanism according to claim 1.   The case is formed of a cylindrical body that contains a working fluid, and the housing and the seal member slide in the cylindrical body, and the upper chamber serving as the first fluid chamber and the second fluid in the cylindrical body, respectively. A piston separated into a lower chamber as a chamber, and a seal member attached to the piston, and configured to control a working fluid flowing through the piston in the cylinder and adjust a damping force. The damping force adjusting mechanism according to any one of claims 1 to 3.

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