JP7737958B2 - buffer - Google Patents

Description

The present invention relates to shock absorbers, and more particularly to adjustable damping force shock absorbers that adjust damping force by controlling the flow of working fluid generated by the stroke of a piston rod.

Patent Document 1 discloses a shock absorber (hereinafter referred to as a "conventional shock absorber") in which a pin portion 85 formed integrally with a pilot case 73 is inserted into the inner periphery of the main valve 51 and main body 52, and a nut 87 attached to the pin portion 85 is tightened to integrate the main valve 51, main body 52, and pilot case 73.

International Publication No. 2021/161980

In conventional shock absorbers, the internal pressure of the annular flow path 21 of the main valve 51 acts as a bending load on the main body 52. Furthermore, conventional shock absorbers are constructed separately from one another: a pilot case 73, on one side of which the back pressure chamber 72 of the main valve 51 is formed, and a seat portion 102 (pilot valve seat portion) on which the pilot valve 71 seats, on the other side. Because the pilot case 73 bears the bending load acting on the main body 52, it was necessary to increase the thickness of the bottom portion 75 (longer axial length). This increased the axial length of the damping force adjustment mechanism 31, which resulted in an increase in the size of the shock absorber.

The objective of this invention is to reduce the size of the shock absorber.

a piston inserted into the cylinder to divide the interior of the cylinder into two chambers; an outer cylinder attached to the outer periphery of the cylinder; a reservoir formed between the cylinder and the outer cylinder and filled with hydraulic fluid and gas; a connecting pipe provided between the cylinder and the outer cylinder and communicating with the interior of the cylinder; and a damping force generating mechanism housed in a valve case attached to the outside of the outer cylinder and connected to the connecting pipe, wherein the damping force generating mechanism has a main valve that generates damping force, a seat member against which the main valve abuts, and a pilot case having a back pressure chamber formed on one side in which internal pressure acts on the main valve in a valve closing direction and a pilot valve seat portion formed on the other side on which a pilot valve that adjusts the internal pressure of the back pressure chamber is seated, and wherein a pin portion formed integrally with the pilot case is inserted into the seat member and the main valve, and a fastening member that fastens the seat member, the main valve, and the pilot case is provided on the pin portion .

This invention makes it possible to shorten the axial length of the damping force adjustment mechanism, thereby enabling the shock absorber to be made more compact.

1 is a cross-sectional view of a damping force adjustable shock absorber according to an embodiment of the present invention. FIG. 2 is an enlarged view of the damping force adjusting mechanism in FIG. 1 .

An embodiment of the present invention will now be described with reference to the accompanying drawings.
As shown in Fig. 1, this embodiment is a so-called horizontally mounted control valve damping force adjustable hydraulic shock absorber 1 (hereinafter referred to as "shock absorber 1") in which a damping force adjustment mechanism 31 is mounted horizontally on the side wall of an outer cylinder 3. For convenience, the up-down direction in Fig. 1 will be referred to as the "up-down direction".

The shock absorber 1 has a twin-cylinder structure with a cylinder 2 inside an outer cylinder 3, and a reservoir 4 formed between the outer cylinder 3 and the cylinder 2. A piston 5 is slidably fitted within the cylinder 2, dividing the interior of the cylinder 2 into two chambers: an upper cylinder chamber 2A and a lower cylinder chamber 2B. The lower end of a piston rod 6 is connected to the piston 5. The upper end of the piston rod 6 passes through the upper cylinder chamber 2A and is inserted into a rod guide 8 and an oil seal 9 attached to the upper ends of the cylinder 2 and outer cylinder 3, protruding outside the cylinder 2.

The piston 5 is provided with an extension passage 11 and a compression passage 12 that connect the upper cylinder chamber 2A and the lower cylinder chamber 2B. The compression passage 12 is provided with a check valve 13 that allows hydraulic fluid to flow from the lower cylinder chamber 2B to the upper cylinder chamber 2A. The extension passage 11 is provided with a disk valve 14 (relief valve) that opens when the pressure in the upper cylinder chamber 2A reaches a set pressure, releasing the pressure in the upper cylinder chamber 2A to the lower cylinder chamber 2B.

A base valve 10 is provided at the lower end of the cylinder 2, separating the cylinder lower chamber 2B from the reservoir 4. The base valve 10 is provided with an extension passage 15 and a compression passage 16 that connect the cylinder lower chamber 2B to the reservoir 4. The extension passage 15 is provided with a check valve 17 that allows hydraulic fluid to flow from the reservoir 4 to the cylinder lower chamber 2B. The compression passage 16 is provided with a disc valve 18 (relief valve) that opens when the pressure in the cylinder lower chamber 2B reaches a set pressure, releasing the pressure in the cylinder lower chamber 2B to the reservoir 4. Hydraulic fluid is sealed in the cylinder 2, and hydraulic fluid and gas are sealed in the reservoir 4.

A separator tube 20 (connecting pipe) is attached to the outer periphery of the cylinder 2 via a pair of upper and lower seal members 19, 19. An annular flow path 21 is formed between the cylinder 2 and the separator tube 20. The annular flow path 21 is connected to the cylinder upper chamber 2A via a passage 22 provided at the upper end of the side wall of the cylinder 2. A cylindrical connection port 23 that protrudes laterally and opens at its tip is provided at the lower end of the side wall of the separator tube 20. A mounting hole 24 is formed in the side wall of the outer cylinder 3 at a position opposite the connection port 23. The mounting hole 24 is positioned coaxially with the connection port 23 and has an inner diameter larger than the outer diameter of the connection port 23. A substantially cylindrical valve case 25 is provided in the side wall of the outer cylinder 3, surrounding the mounting hole 24. The valve case 25 houses a damping force adjustment mechanism 31.

As shown in FIG. 2, the damping force adjustment mechanism 31 includes a back-pressure-type main valve 51 that generates a damping force, an annular main body 52 (seat member) against which the main valve 51 abuts, a back-pressure chamber 72 formed behind the main valve 51, whose internal pressure acts on the main valve 51 in a valve-closing direction, a pilot case 73 on one side (the side approaching the cylinder 2, the left side in FIG. 2) of which the back-pressure chamber 72 is formed, a pilot valve 71 that controls the valve-opening pressure of the main valve 51 by adjusting the internal pressure of the back-pressure chamber 72, a pilot valve seat 74 formed on the other side of the pilot case 73 (the side moving away from the cylinder 2, the right side in FIG. 2) on which the pilot valve 71 is seated, a fail-safe valve 111 provided downstream of the pilot valve 71, and a solenoid 121 that controls the valve-opening pressure of the pilot valve 71.

An annular seat portion 53 is formed on the outer peripheral edge of the other end face (the "right end face" in Figure 2) of the main body 52, against which the outer peripheral edge of the main valve 51 can removably seat. An annular recess 55 is formed on the inner peripheral side of the seat portion 53, in other words, on the upstream side of the main valve 51. On the other hand, a recess 56 is formed on one end face (the "left end face" in Figure 2) of the main body 52, into which the connection port 23 of the separator tube 20 is fitted (inserted). The recess 56 has an inner peripheral surface 57 consisting of an inner cylindrical surface coaxial with the main body 52.

A seal ring 58 is provided in an annular groove (reference number omitted) formed in the inner circumferential surface 57 of the main body 52 (recess 56) to seal between the inner circumferential surface 57 of the main body 52 and the connection port 23 of the separator tube 20. The recess 56 on one side of the main body 52 and the annular recess 55 on the other side are connected by multiple passages 59 extending along the axial direction of the main body 52 (the axial direction of the connection pipe 23, left-right direction in Figure 2).

The inner periphery of the disk-shaped main valve 51 is sandwiched between the inner periphery 54 of the main body 52 and the bottom 75 of the pilot case 73, which is formed in a generally cylindrical shape with a bottom. An annular gasket 60 (elastic seal member) is bonded to the back side of the outer periphery of the main valve 51. An annular recess 77 that forms the back pressure chamber 72 is formed on one end face (the "left end face" in Figure 2) of the pilot case 73 (bottom 75). The outer periphery of the annular recess 77 is an inner cylindrical surface coaxial with the axis (center line) of the pilot case 73, and forms the sliding surface for the gasket 60 of the main valve 51.

An annular seat 79 is formed on the inner peripheral edge of the annular recess 77 on one end face of the pilot case 73. The outer peripheral edge of a disk-shaped back pressure introduction valve 81 is removably seated against the seat 79. The inner peripheral portion of the back pressure introduction valve 81 is sandwiched between the inner peripheral portion 54 of the main body 52 and the bottom 75 of the pilot case 73. Interposed between the inner peripheral portion 54 of the main body 52 and the bottom 75 of the pilot case 73, in this order from one side to the other, are the main valve 51, a retainer, a spacer, another retainer (reference numerals omitted), and the back pressure introduction valve 81. A pin 85, formed integrally with the pilot case 73, is inserted into the axial holes of the main valve 51, the retainer, the spacer, the retainer (reference numerals omitted), and the back pressure introduction valve 81.

The pin portion 85 is arranged coaxially with the pilot case 73 and protrudes to one side (the left side in Figure 2) from the bottom 75 of the pilot case 73. The pin portion 85 is inserted through the axial hole 61 of the main body 52, and one end (tip) is located inside the recess 56 of the main body 52, in other words, inside the connection port 23. A threaded portion 86 is formed at one end of the pin portion 85, and a nut 87 (fastening member) is threaded onto the threaded portion 86. The nut 87 is located (housed) inside the connection port 23, in other words, inside the recess 56 of the main body 52.

By tightening the nut 87 threaded onto the threaded portion 86, an axial force is applied to the upstream valve parts between the washer 88 and the pilot case 73. When tightening the nut 87, a tool is engaged with the two-face width 89 (only one face is shown in Figure 2) formed on the outer peripheral surface of the pilot case 73. In addition, a passage 33, described below, is formed between the two-face width 89 of the pilot case 73 and the yoke 122.

The pilot case 73 has a recess 91 of a fixed depth (axial length) formed on the other side (the "right side" in Figure 2) of the bottom 75. The recess 91 has an inner cylindrical surface 92 coaxial with the axis (center line) of the pilot case 73. The valve chamber 93 of the pilot valve 71 and the fail-safe valve 111 is formed inside the inner cylindrical surface 92. The pilot valve seat portion 74 is formed in the center of the bottom of the recess 91, on which the valve body 82 of the pilot valve 71 is removably seated. A recess 94 (introduction passage) of a fixed depth (axial length) is formed in the center of the pilot valve seat portion 74. In other words, the pilot valve seat portion 74 is formed around the opening periphery of the recess 94.

On the other hand, the pilot case 73 has an annular groove 95 (annular recess) formed inside the seat portion 79 on which the back pressure introduction valve 81 seats. The cross section of the annular groove 95 taken along the axial plane of the pilot case 73 is formed in the shape of a substantially right-angled triangle. The annular groove 95 is formed in the pilot case 73 and communicates with the recess 94 via multiple passages 96 evenly spaced around the axis of the pilot case 73. The passages 96 are inclined (60° in this embodiment) with respect to the axis of the pilot case 73 and are arranged perpendicular to the inner peripheral surface (reference numeral omitted) of the annular groove 95.

The recess 94 is connected to the annular flow path 21 via an axial hole 97 (inlet passage) in the pin portion 85. An inlet orifice 98 is formed at one end of the axial hole 97 (the tip of the pin portion 85) to introduce hydraulic fluid (hydraulic pressure) from the annular flow path 21 to the backpressure chamber 72. The hydraulic fluid in the annular flow path 21 is introduced into the backpressure chamber 72 via the inlet passage, i.e., the inlet orifice 98, axial hole 97, recess 94, passage 96, annular groove 95, and backpressure introduction valve 81. The backpressure introduction valve 81 is also formed at its outer periphery with multiple orifices 99 that constantly connect the backpressure chamber 72 to the annular flow path 21.

The valve body 82 of the pilot valve 71 is formed in a generally cylindrical shape with one end formed in a tapered shape. An outer flange-shaped spring bearing portion 83 is formed on the other side of the valve body 82. The valve body 82 is elastically supported by a pilot spring 112, a fail-safe spring 113, and a fail-safe disk 114, facing the pilot valve seat portion 74, allowing it to move axially. The pilot spring 112 and fail-safe spring 113 can be formed as a single nonlinear spring.

On the other side (the "right side" in Figure 2) of the pilot case 73, there are formed an inner cylindrical surface 92 (recess 91), an inner cylindrical surface 100, and an inner cylindrical surface 102, whose inner diameters increase stepwise from one side to the other (opening side). The inner cylindrical surfaces 92, 100, and 102 are arranged coaxially. The inner cylindrical surface 102 is the inner circumferential surface of a cylindrical portion 101 provided on the other end face of the pilot case 73.

The outer peripheral edge of the pilot spring 112 is supported by a step (reference numeral omitted) between the inner cylindrical surface 92 and the inner cylindrical surface 100. On the other hand, the step (reference numeral omitted) between the inner cylindrical surface 100 and the inner cylindrical surface 102 supports the failsafe spring 113, failsafe disk 114, and washer 115 housed inside the inner cylindrical surface 102. The failsafe spring 113, failsafe disk 114, and washer 115 housed inside the inner cylindrical surface 102 are fixed to the other side of the pilot case 73 by a cap 117 attached to the outer cylindrical surface 103, which is the outer peripheral surface of the cylindrical portion 101.

The cap 117 has multiple notches 118. The notches 118 connect the valve chamber 93 to an annular flow passage 37 formed on the outer periphery of the cap 117. The valve chamber 93 is connected to the reservoir 4 via the axial hole 116 of the washer 115, the notches 118 of the cap 117, the flow passage 37, the passage 33 formed between the flat width 89 of the pilot case 73 and the cylindrical portion 123 of the yoke 122, and the annular flow passage 35 formed on the inner periphery of the valve case 25 and the outer periphery of the main body 52.

The pilot case 73 and the yoke 122 are fastened together by rotating the threaded portion 76 (external thread) formed on the outer peripheral surface of the pilot case 73 and the threaded portion 124 (internal thread) formed on the inner peripheral surface of the cylindrical portion 123 of the yoke 122 relative to each other in the tightening direction. This applies axial force to the downstream valve components between the pilot case 73 and the yoke 122, namely, the pilot spring 112, the failsafe spring 113, the failsafe disk 114, the washer 115, and the cap 117.

Meanwhile, the coil 126, core 127, core 128, plunger 129, and hollow actuating rod 130 are assembled to the other side of the yoke 122 (the "right side" in Figure 2). The actuating rod 130 is formed integrally with the plunger 129, but may also be a separate body. The valve body 82 of the pilot valve 71 is fixed to one end of the actuating rod 130. A spacer 131 and cover 132 are inserted into the other end of the yoke 122, and by plastically processing (crimping) the other peripheral edge of the yoke 122, an axial force is applied to the solenoid's internal components within the yoke 122.

The yoke 122 has a cylindrical portion 123 on one side that fits into the large inner diameter portion 26, which opens to the other side of the valve case 25. The yoke 122 is axially positioned relative to the valve case 25 when one end face of the cylindrical portion 123 abuts against a step portion 27 (the bottom of the large inner diameter portion 26) of the valve case 25. A seal ring 134 attached to the outer surface of the cylindrical portion 123 of the yoke 122 provides a seal between the valve case 25 and the cylindrical portion 123 of the yoke 122. The valve case 25 and the yoke 122 are fastened together by tightening a nut 135 attached to the valve case 25 and compressing a retaining ring 137 attached to an annular groove (reference number omitted) in the yoke 122. The valve case 25 and the yoke 122 are sealed together by a seal ring 29 attached to the outer surface of the valve case 25.

When the coil 126 is de-energized, the spring force of the fail-safe spring 113 urges the valve element 82 in a direction away from the pilot valve seat 74 (to the right in Figure 2). This causes the spring bearing portion 83 of the valve element 82 to abut (seat) against the fail-safe disk 114, thereby closing the fail-safe valve 111. At this time, the pilot spring 112 is separated from the step (reference number omitted) between the inner cylindrical surface 92 and the inner cylindrical surface 100 of the pilot case 73.

When the coil 126 is energized, the operating rod 130 is biased in the seating direction of the valve element 82 (to the left in Figure 2) against the spring forces of the pilot spring 142 and the failsafe spring 113. As a result, the pilot spring 142 abuts against a step (reference number omitted) between the inner cylindrical surfaces 92 and 100 of the pilot case 73, and the valve element 82 seats on the pilot valve seat 74. The valve opening pressure of the valve element 82 is controlled by changing the value of the current passing through the coil 126. Note that in soft mode, when the value of the current passing through the coil 126 is small, the spring force of the pilot spring 142 and the thrust of the plunger 129 are balanced, and the valve element 82 is spaced apart from the pilot valve seat 74 (see Figure 2).

Next, the operation of the shock absorber 1 will be described.
The shock absorber 1 is provided between the sprung portion (vehicle body) and the unsprung portion (wheels) of a vehicle suspension device (not shown). In normal operation, the on-board controller adjusts the opening pressure of the pilot valve 71 by controlling the current flowing through the coil 126 of the solenoid 121 of the damping force adjusting mechanism 31.

During the extension stroke of the piston rod 6, the pressure in the upper cylinder chamber 2A rises, closing the check valve 13 of the piston 5. Before the disc valve 14 opens, the hydraulic fluid in the upper cylinder chamber 2A is pressurized. The pressurized hydraulic fluid passes through the passage 22 and the annular flow path 21 and is introduced into the damping force adjustment mechanism 31 through the connection port 23 of the separator tube 20 (connecting pipe). At this time, the hydraulic fluid equivalent to the amount of hydraulic fluid displaced by the piston 5 flows from the reservoir 4 into the lower cylinder chamber 2B, opening the check valve 17 of the base valve 10. When the pressure in the upper cylinder chamber 2A reaches the opening pressure of the disc valve 14 of the piston 5 and the disc valve 14 opens, the pressure in the upper cylinder chamber 2A is relieved into the lower cylinder chamber 2B. This prevents excessive pressure buildup in the upper cylinder chamber 2A.

Meanwhile, during the compression stroke of the piston rod 6, pressure rises in the cylinder lower chamber 2B, opening the check valve 13 in the piston 5 and closing the check valve 17 in the passage 15 of the base valve 10. Before the disc valve 18 opens, hydraulic fluid in the piston lower chamber 2B flows into the cylinder upper chamber 2A. The volume of hydraulic fluid that the piston rod 6 has invaded into the cylinder 2 is introduced from the cylinder upper chamber 2A through the passage 22, the annular flow path 21, and the connection port 23 of the separator tube 20 (connecting pipe) into the damping force adjustment mechanism 31. When the pressure in the cylinder lower chamber 2B reaches the opening pressure of the disc valve 18 and the disc valve 18 opens, the pressure in the cylinder lower chamber 2B is relieved to the reservoir 4. This prevents excessive pressure buildup in the cylinder lower chamber 2B.

The hydraulic fluid introduced into the damping force adjustment mechanism 31 flows into the annular groove 95 via the inlet orifice 98 formed in the pin portion 85 (pin member), the axial hole 97 of the pin portion 85, the recess 94 of the pilot case 73, and the passage 96. When the pressure in the opening direction of the back pressure introduction valve 81 (the pressure inside the annular groove 95) exceeds the set pressure, the back pressure introduction valve 81 opens and the hydraulic fluid is introduced into the back pressure chamber 72. Before the main valve 51 opens (low piston speed range), the hydraulic fluid introduced into the damping force adjustment mechanism 31 passes through the inlet orifice 98, the axial hole 97, and the recess 94, opening the valve element 82 (pilot valve 71), and flows into the valve chamber 93 in the pilot case 73.

The hydraulic fluid that flows into the valve chamber 93 flows between the valve element 82 and the failsafe disk 114, through the axial hole 116 in the washer 115, the notch 118 in the cap 117, the flow path 37, the passage 33 between the pilot case 73 and the yoke 112, the annular flow path 35, and the outer periphery of the main body 52 to the reservoir 4. When the piston speed increases and the pressure in the annular recess 55, which is connected to the connection port 23 via the passage 59 in the main body 52, reaches the opening pressure of the main valve 51, the main valve 51 opens, and the hydraulic fluid in the annular flow path 21 flows through the connection port 23, the passage 59, the annular recess 55, and the main valve 51 to the reservoir 4.

In this way, during both the extension stroke and compression stroke of the piston rod 6, the damping force adjustment mechanism 31 generates a damping force by the inlet orifice 98 and the valve opening pressure of the pilot valve 71 (valve element 82) before the main valve 51 opens (low piston speed range), and generates a damping force according to the opening degree of the main valve 51 after the main valve 51 opens (medium piston speed range). By controlling the supply of current to the coil 126 to adjust the opening pressure of the pilot valve 71, the damping force can be directly controlled regardless of the piston speed. Furthermore, by controlling the supply of current to the coil 126 to adjust the opening pressure of the pilot valve 71, the back pressure introduction valve 81 is opened, adjusting the pressure of the hydraulic fluid introduced into the back pressure chamber 72, thereby enabling adjustment of the damping force characteristics over a wide range.

In addition, if the thrust of the plunger 129 is lost due to a failure such as a broken coil 126 or a malfunction of the on-board controller, the spring force of the failsafe spring 113 will retract the valve element 82, opening the pilot valve 71 and causing the spring receiving portion 83 of the valve element 82 to abut against the failsafe disk 114, thereby blocking communication between the valve chamber 93 and the annular flow path 35 inside the valve case 25.

As a result, the flow of hydraulic fluid from the annular flow path 21 through the inlet orifice 98, the axial hole 97 of the pin portion 85, the recess 94, the valve chamber 93, the axial hole 116 of the washer 115, the notch 118 of the cap 117, the flow path 37, the passage 33, the annular flow path 35, and the outer periphery of the main body 52 to the reservoir 4 is controlled by the fail-safe valve 111. By varying the valve opening pressure of the fail-safe disk 114, the desired damping force can be obtained. At the same time, the internal pressure of the back pressure chamber 72, i.e., the valve opening pressure of the main valve 51, can be adjusted, ensuring appropriate damping force even in the event of a failure.

In conventional shock absorbers, the internal pressure of the main valve's valve chamber acts as a bending load on the main body. Furthermore, conventional shock absorbers are constructed separately, with a pilot case on one side forming a back pressure chamber for the main valve, and a pilot valve seat on the other side where the pilot valve seats. Because the pilot case bears the bending load acting on the main body, it was necessary to make the bottom thicker (longer axial length). This resulted in a longer axial length for the damping force adjustment mechanism, which in turn led to an increase in the size of the shock absorber.

In contrast to this, in the present embodiment, a back pressure chamber 72 is formed on one side of the pilot case 73, in which internal pressure acts in a direction to close the main valve 51, and a pilot valve seat portion 74 is formed on the other side of the pilot case 73, in which the valve body 82 of the pilot valve 71 that adjusts the internal pressure of the back pressure chamber 72 is seated and releasably seated. In other words, the pilot case and pilot body of a conventional shock absorber are integrated into the pilot case 73 of the shock absorber 1 of the present embodiment, so that the axial length of the damping force adjusting mechanism 31 can be shortened by the thickness (axial length) of the bottom part of the pilot case in the conventional shock absorber that received the main body. This makes it possible to reduce the size of the shock absorber 1, thereby improving the degree of freedom in designing a vehicle suspension device.
In addition, in this embodiment, the pilot case and pilot body are integrally formed, which is required in conventional shock absorbers. This eliminates the need for a seal ring to seal between the pilot case and pilot body and the need to machine an annular groove to fit the seal ring. This reduces the number of parts and the number of steps (machining and assembly), thereby reducing manufacturing costs. Furthermore, by eliminating the seal ring to seal between the pilot case and pilot body, the reliability of the damping force adjusting mechanism 31 and, ultimately, the shock absorber can be improved.

1. Shock absorber, 2. Cylinder, 3. Outer cylinder, 4. Reservoir, 5. Piston, 20. Separator tube (connecting pipe), 31. Damping force adjustment mechanism, 51. Main valve, 52. Main body (seat member), 71. Pilot valve, 72. Back pressure chamber, 73. Pilot case, 74. Pilot valve seat portion

Claims (2)

a cylinder filled with hydraulic fluid;
a piston inserted into the cylinder to divide the interior of the cylinder into two chambers;
an outer cylinder provided on the outer periphery of the cylinder;
a reservoir formed between the cylinder and the outer tube and containing a hydraulic fluid and a gas;
a connecting pipe provided between the cylinder and the outer cylinder and communicating with the inside of the cylinder;
a damping force generating mechanism housed in a valve case provided outside the outer cylinder and connected to the connecting pipe;
A shock absorber comprising:
The damping force generating mechanism includes:
A main valve that generates damping force;
a seat member against which the main valve abuts;
a pilot case having a back pressure chamber formed on one side thereof, in which internal pressure acts on the main valve in a valve closing direction, and a pilot valve seat portion formed on the other side thereof, on which a pilot valve for adjusting the internal pressure of the back pressure chamber is seated;
and
a pin portion formed integrally with the pilot case is inserted into the seat member and the main valve, and a fastening member that fastens the seat member, the main valve, and the pilot case together is provided on the pin portion . 2. The shock absorber according to claim 1 ,
A shock absorber characterized in that an inlet orifice for introducing hydraulic fluid into the back pressure chamber is formed in the pin portion.