WO2018123735A1 - Shock absorber - Google Patents

Abstract

A piston (9) has two piston bodies (201, 202). A first passage (261) by which a through-hole (211) communicates with a communicating passage (212) is formed on a coupling face (210) on at least one of the piston bodies (201). A second passage (70) by which the through-hole (211) communicates with the communicating passage (212) is formed on the non-coupling face (215) on the one piston body (201), a plate member (76a) provided by abutting the non-coupling face (215), or a disc valve (75a).

Description

Shock absorber

The present invention relates to a shock absorber.
This application claims priority based on Japanese Patent Application No. 2016-250811 filed in Japan on December 26, 2016, the contents of which are incorporated herein by reference.

The shock absorber includes a shock absorber having a damping force variable mechanism that varies the damping force characteristic according to the vibration state (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-202801

There is a demand to increase the degree of freedom of tuning in the shock absorber.

The present invention provides a shock absorber that can increase the degree of tuning freedom.

In the shock absorber according to the first aspect of the present invention, the piston has two piston bodies, and each piston body has a through-hole into which a piston rod is inserted and a plurality of extending side and contracting side communication passages. An annular valve seat is formed on the non-coupling surface of one of the piston bodies so that the extension side communication path is on the inner peripheral side and the contraction side communication path is on the outer peripheral side. An annular valve seat is formed on the non-coupling surface of the other piston body such that the communication path on the contraction side is on the inner peripheral side and the communication path on the expansion side is on the outer peripheral side. A disc valve that contacts the valve seat is provided on the non-coupled surface of the piston body, and a first passage that communicates the through hole and the communication passage is formed on at least the coupled surface of the one piston body. , Non-binding of the one piston body Surface or wherein the non-binding surface plate-like member or the disk valve is provided in contact with, a second passage communicating with said communication passage and said through hole is formed.

According to the present invention, the degree of freedom in tuning can be increased.

It is sectional drawing which shows the shock absorber which concerns on one Embodiment of this invention. It is an expanded sectional view of the important section of the buffer concerning one embodiment of the present invention. It is the figure which looked at one piston body of the buffer concerning one embodiment of the present invention from the joint surface side. It is sectional drawing of one piston body of the buffer which concerns on one Embodiment of this invention. It is sectional drawing of the other piston body of the buffer which concerns on one Embodiment of this invention. It is the figure which looked at the other piston body of the buffer which concerns on one Embodiment of this invention from the coupling surface side.

A shock absorber according to an embodiment of the present invention will be described below with reference to the drawings.

The shock absorber 1 according to the present embodiment is a hydraulic shock absorber in which an oil liquid is used as a working fluid. As shown in FIG. 1, the shock absorber 1 has a multi-cylinder cylinder 4 having an inner cylinder 2 and an outer cylinder 3. The outer cylinder 3 is larger in diameter than the inner cylinder 2 and is arranged coaxially with the inner cylinder 2 so as to cover the inner cylinder 2. A reservoir chamber 5 is provided between the inner cylinder 2 and the outer cylinder 3. In addition, this embodiment can be used not only for a double cylinder type but also for a single cylinder type shock absorber.

The shock absorber 1 has a piston rod 8 and a piston 9. The piston 9 is connected to one end of the piston rod 8 in the axial direction. Therefore, the piston 9 moves integrally with the piston rod 8. The piston rod 8 is disposed on the central axis of the inner cylinder 2 and the outer cylinder 3, and the central portion is inserted into the inner cylinder 2 and the outer cylinder 3 (that is, the cylinder 4) from one axial end thereof, and the shaft The other end in the direction extends from the inner cylinder 2 and the outer cylinder 3 (that is, the cylinder 4) to the outside. The piston 9 is slidably fitted in the inner cylinder 2 of the cylinder 4, and divides the inner cylinder 2 into two chambers 11 and 12. In other words, the piston 9 is slidably provided in the cylinder 4, and one end thereof is connected to the piston rod 8 extending to the outside of the cylinder 4. The piston rod 8 is disposed so as to penetrate the chamber 11 out of the chambers 11 and 12. Therefore, the chamber 11 is a rod-side chamber in which the piston rod 8 is disposed in the shock absorber 1.

An oil liquid as a working fluid is sealed in the inner cylinder 2 of the cylinder 4, and an oil as a working fluid is placed in the reservoir chamber 5 between the inner cylinder 2 and the outer cylinder 3 in the cylinder 4. Liquid and high-pressure (about 20 to 30 atmospheres) gas are enclosed. That is, the working fluid is sealed in the cylinder 4 having the inner cylinder 2 and the outer cylinder 3. The reservoir chamber 5 may be filled with atmospheric pressure air instead of high-pressure gas.

The shock absorber 1 has a rod guide 15, a seal member 16, and a friction member 17. The shock absorber 1 has a base valve 18. The rod guide 15 is disposed at the end position of the piston rod 8 on the external projecting side of the cylinder 4 and has a stepped shape. The large diameter side of the rod guide 15 is fitted inside the outer cylinder 3, and the small diameter side of the rod guide 15 is fitted inside the inner cylinder 2. The seal member 16 is disposed at the end of the cylinder 4 and outside the rod guide 15 in the axial direction of the cylinder 4. The friction member 17 is disposed between the seal member 16 and the rod guide 15. The base valve 18 is disposed at the end of the cylinder 4 opposite to the axial rod guide 15, the seal member 16, and the friction member 17.

The rod guide 15, the seal member 16, and the friction member 17 are all annular shapes. The piston rod 8 is slidably inserted inside the rod guide 15, the seal member 16 and the friction member 17. The rod guide 15 supports the piston rod 8 such that the piston rod 8 can move in the axial direction while restricting its radial movement, and guides the movement of the piston rod 8.
The seal member 16 is in sliding contact with the outer peripheral portion of the piston rod 8 moving in the axial direction at the inner peripheral portion thereof, and the high-pressure gas and the oil liquid in the reservoir chamber 5 in the outer cylinder 3 Is prevented from leaking outside. The friction member 17 is in sliding contact with the outer peripheral portion of the piston rod 8 at the inner peripheral portion thereof, and generates frictional resistance on the piston rod 8. The friction member 17 is not a member intended for sealing.

The outer cylinder 3 of the cylinder 4 includes a cylindrical body member 21 and a bottom cover member 22, and the bottom cover member 22 is fitted to one end of the body member 21 in the axial direction. The bottom lid member 22 has a bottom lid portion 23 and a rod-like portion 24. The outer peripheral part of the bottom cover part 23 is fitted to the inner peripheral part of the trunk member 21. The rod-shaped part 24 extends from the center in the radial direction of the bottom cover part 23 to the side opposite to the body member 21. The bottom lid member 22 is fixed to the trunk member 21 in a sealed state by welding with the bottom lid portion 23 fitted to the trunk member 21. An attachment member 25 is fixed to the rod-like portion 24 by welding on the opposite side of the rod-like portion 24 to the side where the bottom lid portion 23 is disposed. Of the chambers 11 and 12, the chamber 12 on the bottom lid portion 23 side of the cylinder 4 is a bottom side chamber in the cylinder 4.

An opening 27 is formed on the opposite side of the body member 21 from the side on which the bottom cover member 22 is disposed, and the opening 27 has a locking portion 28. The sealing member 16 and the rod guide 15 described above are fitted to the opening 27 side of the body member 21. The locking portion 28 protrudes radially inward from the position of the end portion of the opening 27 in the body member 21, and sandwiches the seal member 16 between the rod guide 15.

A base body 30 of the base valve 18 is disposed on the inner side of the cylinder 4 in the bottom cover portion 23 of the outer cylinder 3. The base body 30 defines the chamber 12 in the cylinder 4 and the reservoir chamber 5 described above. The base body 30 is formed in a stepped shape in which the outer diameter on one side in the axial direction is smaller than the outer diameter on the other side. The base body 30 is placed on the bottom lid portion 23 on the large diameter side.

The inner cylinder 2 of the cylinder 4 has a cylindrical shape. The inner cylinder 2 is supported in a state where one end side in the axial direction is fitted to the small diameter side of the base body 30 of the base valve 18, and the other end side in the axial direction is inside the opening 27 of the outer cylinder 3. It is supported in a fitted state on the side.

An insertion hole 29 penetrating in the axial direction is formed in the base body 30 of the base valve 18 in the center in the radial direction, and a flow passage 31a penetrating the base body 30 in the axial direction around the insertion hole 29. , 31b are formed. These flow passages 31 a and 31 b are configured to allow communication between the chamber 12 in the inner cylinder 2 and the reservoir chamber 5 between the outer cylinder 3 and the inner cylinder 2. Further, the base body 30 is provided with a disk valve 33a on the side opposite to the bottom cover part 23 and a disk valve 33b on the bottom cover part 23 side. The disk valve 33a is a check valve, and is configured to be able to open and close the outer flow passage 31a. The disk valve 33b is a damping valve, and is configured to be able to open and close the inner flow passage 31b. In the base body 30, a rivet 35 is inserted into the insertion hole 29 from the bottom lid portion 23 side, and the disk valves 33 a and 33 b are connected to a head portion 36 at one end of the rivet 35 and a crimping portion 37 at the other end. The radial inner portion is clamped and attached to the base body 30.

The disk valve 33b generates a damping force while allowing oil to flow from the chamber 12 to the reservoir chamber 5 via the passage hole (not shown) of the disk valve 33a and the flow passage 31b of the base body 30, while generating a damping force. Regulates the flow of oil in the direction. On the contrary, the disc valve 33a allows the flow of oil from the reservoir chamber 5 to the chamber 12 through the flow passage 31a of the base body 30 without resistance, while restricting the flow of oil in the reverse direction. . The disc valve 33b opens the flow passage 31b when the piston rod 8 moves to the contraction side that increases the amount of entry into the cylinder 4 and the piston 9 moves to the chamber 12 side and the pressure in the chamber 12 rises. This is a contraction-side damping valve that generates damping force. Further, the disk valve 33a opens the flow passage 31a when the piston rod 8 moves to the extending side that increases the amount of protrusion from the cylinder 4 and the piston 9 moves to the chamber 11 side and the pressure in the chamber 12 decreases. However, in this case, the suction valve allows the oil liquid to flow from the reservoir chamber 5 into the chamber 12 without substantially generating a damping force.

When the piston rod 8 moves to the extension side and the amount of protrusion from the cylinder 4 increases, the corresponding oil liquid flows from the reservoir chamber 5 to the chamber 12 through the flow passage 31a while opening the disc valve 33a. Conversely, when the piston rod 8 moves to the contraction side and the amount of insertion into the cylinder 4 increases, the corresponding amount of oil flows from the chamber 12 to the reservoir chamber 5 through the flow passage 31b while opening the disc valve 33b.

The extension side damping force may be positively generated by the disk valve 33a as a check valve. Further, these disc valves 33a and 33b may be eliminated to form an orifice.

The piston rod 8 has a mounting shaft portion 40 and a main shaft portion 41. The attachment shaft portion 40 is a portion to which the piston 9 is attached, and is formed on the distal end side where the piston rod 8 is inserted into the cylinder 4. The main shaft portion 41 is a portion other than the mounting shaft portion 40 of the piston rod 8, and the outer diameter of the main shaft portion 41 is larger than the outer diameter of the mounting shaft portion 40. A retainer 42 extending radially outward is fixed to the main shaft portion 41, and a buffer body 43 made of an annular elastic material is provided opposite to the mounting shaft portion 40 of the retainer 42.

As shown in FIG. 2, the piston 9 has a plurality of flow passages 50a (only one place is shown in the cross section in FIG. 2) and a plurality of flow passages 50a (only one place is shown in the cross section in FIG. 2). A path 50b is provided. The flow passage 50a and the flow passage 50b allow the chamber 11 and the chamber 12 to communicate with each other. During the movement of the piston 9 toward the chamber 11, that is, in the extension stroke in which the piston rod 8 extends from the cylinder 4, a later-described damping force generation mechanism 51b provided for the flow passage 50b closes the flow passage 50b. For this reason, the oil liquid flows out from the chamber 11 which is one of the chamber 11 and the chamber 12 toward the chamber 12 which is the other through the flow passage 50 a by the movement of the piston 9. On the other hand, during the movement of the piston 9 toward the chamber 12, that is, in the contraction stroke in which the piston rod 8 enters the cylinder 4, a later-described damping force generating mechanism 51a provided for the flow passage 50a causes the flow passage 50a. Block. For this reason, the oil liquid flows out from the chamber 12 which is the other of the chamber 11 and the chamber 12 toward the one chamber 11 through the flow passage 50 b by the movement of the piston 9. The piston 9 has the same number of flow passages 50a and 50b.

The flow passages 50a are formed at an equal pitch so that one flow passage 50b is sandwiched between the adjacent flow passages 50a in the circumferential direction. In the flow passage 50a, one side in the axial direction (the chamber 11 side) of the piston 9 opens radially outward, and the other side in the axial direction (the chamber 12 side) opens radially inward. A damping force generating mechanism 51a that generates a damping force is provided in these flow passages 50a. The damping force generation mechanism 51 a is disposed on the chamber 12 side in the axial direction of the piston 9. As described above, the flow passage 50a constitutes an extension-side flow passage through which the oil liquid flows out of the chamber 11 during the extension stroke. The damping force generation mechanism 51a provided for the flow passage 50a is an extension-side damping force generation mechanism that generates a damping force by suppressing the flow of oil in the extension-side flow passage 50a.

The flow passages 50b are formed at an equal pitch so that one flow passage 50a is sandwiched between the adjacent flow passages 50b in the circumferential direction. In the flow passage 50b, the other axial side (the chamber 12 side) of the piston 9 is opened radially outward, and the one axial side (the chamber 11 side) is opened radially inward. A damping force generation mechanism 51b that generates a damping force is provided in these flow passages 50b. The damping force generation mechanism 51b is disposed on the chamber 11 side in the axial direction of the piston 9. The flow passage 50b constitutes a flow passage on the contraction side from which the oil liquid flows out of the chamber 12 during the above-described contraction stroke. The damping force generation mechanism 51b provided for the flow path 50b is a contraction-side damping force generation mechanism that generates a damping force by suppressing the flow of oil in the contraction-side flow path 50b.

The piston rod 8 is formed with a passage hole 55 that penetrates the mounting shaft portion 40 in the radial direction at the position of the mounting shaft portion 40. Further, a passage hole 56 having a diameter larger than that of the passage hole 55 is formed in the piston rod 8 along the axial direction toward the side opposite to the main shaft portion 41. The passage hole 56 communicates with the passage hole 55 and opens at the distal end portion of the attachment shaft portion 40. These passage holes 55 and 56 constitute an in-rod passage 57 (third passage) provided in the piston rod 8.

The damping force variable mechanism 58 is attached to the piston rod 8 on the side opposite to the main shaft portion 41 with respect to the piston 9 of the mounting shaft portion 40. The damping force varying mechanism 58 is attached so as to cover the passage hole 56 of the rod inner passage 57, and the inside of the damping force varying mechanism 58 communicates with the rod inner passage 57.

The above-described shock absorber 1 is provided for each wheel of the vehicle. At that time, for example, one side of the shock absorber 1 is supported by the vehicle body, and the other side is fixed to the wheel side. Specifically, the piston rod 8 is connected to the vehicle body side, and the attachment member 25 on the side opposite to the protruding side of the piston rod 8 of the cylinder 4 is connected to the wheel side. In contrast to the above, the other side of the shock absorber 1 may be supported by the vehicle body, and one side of the shock absorber 1 may be fixed to the wheel side.

When the wheels vibrate as the vehicle travels, the positions of the cylinder 4 and the piston rod 8 change relative to the vibrations. The change is suppressed by the fluid resistance of the passage formed in the piston 9. As will be described in detail below, the fluid resistance of the passage formed in the piston 9 is made different depending on the speed and amplitude of vibration, and the ride comfort is improved by suppressing the vibration.
Between the cylinder 4 and the piston rod 8, in addition to vibration generated by the wheels, inertial force and centrifugal force generated in the vehicle body as the vehicle travels also act. For example, a centrifugal force is generated in the vehicle body when the traveling direction is changed by a steering operation, and a force based on the centrifugal force acts between the cylinder 4 and the piston rod 8. As will be described below, the shock absorber 1 of the present embodiment has good characteristics against vibration based on the force generated in the vehicle body as the vehicle travels, and high stability during travel of the vehicle is obtained. It is done.

The piston 9 has a substantially disc-shaped piston main body 61 and a sliding contact member 62 attached to the outer peripheral surface of the piston main body 61. The piston 9 is in sliding contact with the inner peripheral surface of the inner cylinder 2 of the cylinder 4 at the sliding contact member 62. An insertion hole 63 is formed in the piston body 61 so as to penetrate in the axial direction at the center in the radial direction, and the mounting shaft portion 40 of the piston rod 8 is inserted into the insertion hole 63. The flow passages 50 a and 50 b described above are formed in the piston main body 61 so as to surround the insertion hole 63.

A valve seat 71 a is formed at the end of the piston body 61 on the chamber 12 side in the axial direction. The valve seat 71a is formed in an annular shape outside the one end opening position of the flow passage 50a on the extension side. A valve seat 71 b is formed at the end of the piston body 61 on the chamber 11 side in the axial direction. The valve seat 71b is formed in an annular shape outside the opening position of one end of the flow passage 50b on the contraction side. The valve seat 71a constitutes a damping force generation mechanism 51a, and the valve seat 71b constitutes a damping force generation mechanism 51b.

In the piston main body 61, the side opposite to the insertion hole 63 of the valve seat 71a is an annular stepped portion 72b having an axial height lower than that of the valve seat 71a. The other end of the flow passage 50b on the contraction side is opened at the position of the stepped portion 72b. Similarly, in the piston main body 61, the side opposite to the insertion hole 63 of the valve seat 71b is an annular stepped portion 72a having a lower axial height than the valve seat 71b. The other end of the flow passage 50a on the extending side is opened at the position of the stepped portion 72a.

The damping force generation mechanism 51a includes the above-described valve seat 71a and an annular disc valve 75a that can be seated on the valve seat 71a. The disk valve 75a is configured by overlapping a plurality of annular single disks 74a. A plate-like member 76a having an outer diameter smaller than the outer diameter of the disk valve 75a is arranged on the piston body 61 side of the disk valve 75a. An annular valve regulating member 77a having an outer diameter smaller than the outer diameter of the disk valve 75a is disposed on the opposite side of the disk valve 75a from the piston body 61. The plate-like member 76a is configured by overlapping a plurality of annular single disks 79a.

The damping force generating mechanism 51a has a fixed orifice 78a between the valve seat 71a and the disc valve 75a that allows the flow passage 50a to communicate with the chamber 12 even when they are in contact with each other.
The fixed orifice 78a is formed by a groove formed in the valve seat 71a or an opening formed in the disc valve 75a. The disc valve 75a opens the flow passage 50a by separating from the valve seat 71a. At that time, the valve regulating member 77a regulates deformation beyond the regulation in the opening direction of the disc valve 75a. The damping force generation mechanism 51a is provided in the flow passage 50a, and generates a damping force by suppressing the flow of the oil liquid generated in the flow passage 50a by sliding the piston 9 toward the chamber 11 side.

Similarly, the damping force generation mechanism 51b includes the above-described valve seat 71b and an annular disc valve 75b that can be seated on the valve seat 71b. The disk valve 75b is also configured by overlapping a plurality of annular single disks 74b. A plate-like member 76b having a smaller diameter than the disk valve 75b is disposed on the piston body 61 side of the disk valve 75b, and an annular member having a smaller diameter than the disk valve 75b is disposed on the opposite side of the disk valve 75b from the piston body 61. The valve regulating member 77b is arranged. The valve regulating member 77 b is in contact with the end surface of the main shaft portion 41 of the piston rod 8 on the mounting shaft portion 40 side.

The damping force generating mechanism 51b has a fixed orifice 78b between the valve seat 71b and the disk valve 75b, which allows the flow passage 50b to communicate with the chamber 11 even when they are in contact with each other.
The fixed orifice 78b is formed by a groove formed in the valve seat 71b or an opening formed in the disk valve 75b. The disc valve 75b opens the flow passage 50b by separating from the valve seat 71b. At that time, the valve restricting member 77b restricts deformation beyond the regulation in the opening direction of the disc valve 75b. The damping force generation mechanism 51b is provided in the flow passage 50b, and generates a damping force by suppressing the flow of the oil liquid generated in the flow passage 50b by sliding the piston 9 toward the chamber 12 side.

Among the single disks 79a constituting the plate member 76a, the single disk 79a closest to the piston main body 61 is notched on the inner peripheral side, and the plate-shaped member inner passage 70 that always communicates the insertion hole 63 and the flow passage 50a. (Second passage) is formed. The passage hole 55 constituting the rod inner passage 57 of the piston rod 8 is opened facing the inner peripheral surface of the insertion hole 63 of the piston main body 61.

The piston main body 61 is composed of two piston bodies 201 and 202. Therefore, the piston 9 has two piston bodies 201 and 202. One piston body 201 on the chamber 12 side is coupled in contact with the other piston body 202 on the chamber 11 side at its coupling surface 210.

The piston body 201 is formed with a through hole 211 that constitutes a part of the above-described insertion hole 63 so as to penetrate in the axial direction at the center in the radial direction. The piston body 201 has a plurality of extending communication passages 212 that respectively constitute a part of the plurality of extending flow passages 50a and a plurality of contracting flow passages outside the through hole 211 in the radial direction. A plurality of contraction-side communication passages 213 that respectively constitute a part of 50b are provided. The piston body 201 is formed with the annular valve seat 71a and the stepped portion 72b on the non-coupling surface 215 opposite to the coupling surface 210, and contacts the valve seat 71a on the non-coupling surface 215. A disk valve 75a is provided.
Further, a plate-like member 76a is provided in contact with the non-bonding surface 215. One side surface of the plate-like member 76a comes into contact with the non-coupling surface 215 of the piston body 201, and the other side surface of the plate-like member 76a comes into contact with the disc valve 75a. The outer diameter of the plate member 76a is smaller than the outer diameter of the valve seat 71a. The plate-like member internal passage 70 formed in the plate-like member 76 a communicates the through hole 211 and the communication passage 212.

As described above, the piston body 201 is provided with a through hole 211 into which the piston rod 8 is inserted, a plurality of extension-side communication passages 212, and a contraction-side communication passage 213. On the non-coupling surface 215 of the piston body 201, an annular valve seat 71a is provided so that the extension side communication passage 212 is on the inner peripheral side and the contraction side communication passage 213 is on the outer peripheral side. In the circumferential direction of the piston body 201, the communication passage 212 is formed at an equal pitch so that one communication passage 213 is sandwiched between adjacent ones.

As shown in FIGS. 3 and 4, the coupling surface 210 of the piston body 201 is positioned between the through hole 211 and the communication path 213 so that the positions of the communication path 213 and the piston body 201 in the circumferential direction are aligned. A convex portion 221 protruding in the axial direction of 201 is formed. The same number of protrusions 221 as the communication passages 213 (specifically, five) are formed. On the coupling surface 210 of the piston body 201, a groove portion 222 extending in the radial direction of the piston body 201 is formed between the through hole 211 and the communication path 212 by aligning the positions of the communication path 212 and the piston body 201 in the circumferential direction. Has been.
The number of the groove portions 222 is the same as that of the communication passage 212 (specifically, five).

As shown in FIG. 2, the other piston body 202 is coupled to one piston body 201 at the coupling surface 230 in contact with the coupling surface 210.

In the piston body 202, a through hole 231 constituting a part of the insertion hole 63 is formed so as to penetrate in the axial direction at the center in the radial direction. The inner diameter of the through hole 231 is smaller than the inner diameter of the through hole 211, and the mounting shaft portion 40 of the piston rod 8 is fitted into the through hole 231. In the piston body 202, a plurality of extending communication passages 232 that respectively constitute a part of the plurality of extending flow passages 50 a and a plurality of contracting flow passages are formed outside the through hole 231 in the radial direction. A plurality of contraction-side communication passages 233 that respectively constitute a part of 50b are provided. The piston body 202 is formed with the annular valve seat 71b and the stepped portion 72a on the non-coupling surface 235 opposite to the coupling surface 230. The non-coupling surface 235 contacts the valve seat 71b. A disk valve 75b is provided. In addition, a plate-like member 76b is provided in contact with the non-bonding surface 235. One side surface of the plate-like member 76b is in contact with the non-coupling surface 235 of the piston body 202, and the other side surface of the plate-like member 76b is in contact with the disc valve 75b. The outer diameter of the plate member 76b is smaller than the outer diameter of the valve seat 71b.

As described above, the piston body 202 is provided with a through hole 231 into which the piston rod 8 is inserted, a plurality of extension-side communication passages 232, and a contraction-side communication passage 233. An annular valve seat 71b is provided on the non-coupling surface 235 of the piston body 202 so that the contraction-side communication passage 233 is on the inner peripheral side and the extension-side communication passage 232 is on the outer peripheral side. In the circumferential direction of the piston body 202, the communication paths 232 are formed at an equal pitch so that one communication path 233 is sandwiched between adjacent communication paths 232.

As shown in FIG. 5 and FIG. 6, the coupling surface 230 of the piston body 202 is positioned between the through hole 231 and the communication path 233 so that the positions of the communication path 233 and the piston body 202 in the circumferential direction are aligned. A recess 241 that is recessed in the axial direction 202 is formed. The same number of recesses 241 as the communication path 233 (specifically, five) are formed. The piston body 201 and the piston body 202 are coupled by abutting the coupling surface 210 and the coupling surface 230. At this time, the plurality of convex portions 221 are fitted into the plurality of concave portions 241 one by one. Thus, the piston body 201 and the piston body 202 are positioned in the radial direction and the circumferential direction. That is, all the communication paths 212 communicate with the corresponding communication paths 232 in position, and all the communication paths 213 communicate with the corresponding communication paths 233 in position. The convex portion 221 and the concave portion 241 that are engaged with each other are engaging portions 251 (rotation restricting means) that restrict relative rotation of the piston bodies 201 and 202, and the piston main body 61 includes a plurality of engaging portions 251. (Specifically, five) are provided.

As shown in FIG. 2, when the piston body 201 and the piston body 202 are coupled as described above by abutting the coupling surface 210 and the coupling surface 230, the groove portion 222 provided on the coupling surface 210 of the piston body 201 The coupling surface 230 of the piston body 202 forms an in-piston passage 261 (first passage) that communicates the through hole 211 and the communication passage 212. In other words, the coupling surface 210 of the piston body 201 is formed with an in-piston passage 261 that connects the through hole 211 and the communication passage 212. As shown in FIG. 3, the groove 222 is provided between a plurality of adjacent engaging portions 251, and therefore, the piston passage 261 is also provided between the adjacent engaging portions 251. As shown in FIG. 2, an axial passage 265 (fourth passage) is provided between the through hole 211 of the piston body 201 and the mounting shaft portion 40 of the piston rod 8 having an outer diameter smaller than the inner diameter of the through hole 211. Through this axial passage 265, the rod inner passage 57 provided in the piston rod 8 is always in communication with the plate member inner passage 70 and the piston inner passage 261. In other words, the axial passage 265 is provided on the inner peripheral side of the piston body 201, and communicates the piston passage 261, the plate-like member passage 70, and the rod passage 57. The plate-like member inner passage 70, the piston inner passage 261, the axial passage 265, and the rod inner passage 57 are always in communication with the chamber 11 via the flow passage 50a.

A male screw 80 is formed at the tip of the mounting shaft portion 40 of the piston rod 8, and the damping force variable mechanism 58 is screwed onto the male screw 80. The damping force variable mechanism 58 is a frequency sensitive unit that makes the damping force variable without being controlled from the outside by the frequency (vibration state). The damping force varying mechanism 58 is screwed into the male screw 80 and includes the valve restricting member 77a, the disc valve 75a, the plate-like member 76a, the piston 9, the plate-like member 76b, the disc valve 75b, and the valve restricting member 77b. It is sandwiched between the end surface of the main shaft portion 41 of the piston rod 8 and also serves as a nut.

The damping force variable mechanism 58 includes a housing 85 including a lid member 82 and a housing body 83, a free piston 87, an O-ring 88 that is a rubber member, and an O-ring 89 that is a rubber member. . The lid member 82 is formed with a female screw 81 that is screwed into the male screw 80 on one end side of the piston rod 8. The housing body 83 is formed in a substantially cylindrical shape, and is attached to the lid member 82 so that one end opening side of the housing body 83 is closed. The free piston 87 is slidably inserted into the housing 85. The O-ring 88 is interposed between the free piston 87 and the lid member 82 of the housing 85, and contraction-side elasticity that compresses and deforms when the free piston 87 moves toward the axial lid member 82 with respect to the housing 85. Functions as a body. The O-ring 89 is interposed between the free piston 87 and the housing main body 83 of the housing 85, and is an elastic body on the extension side that compresses and deforms when the free piston 87 moves to the opposite side of the housing 85. Function. In FIG. 2, the O-rings 88 and 89 in the natural state are shown for convenience. In particular, since the O-ring 89 also functions as a seal, it is desirable that the O-ring 89 is always arranged so as to be deformed into a non-circular cross section when attached.
The above-described O-ring 88 functions as a resistance element that compresses and deforms when the free piston 87 moves in one direction and generates a resistance force against the displacement of the free piston 87, and the O-ring 89 has a free piston 87 in the other direction. When it moves, it functions as a resistance element that compresses and deforms and generates resistance against the displacement of the free piston 87.

The lid member 82 is formed mainly by cutting. The lid member 82 includes a lid inner cylinder part 91, a lid substrate part 92, a lid outer cylinder part 93, and a fitting convex part 94. The lid inner cylinder portion 91 is formed in a substantially cylindrical shape, and the above-described female screw 81 is formed on the inner peripheral portion thereof. The lid substrate portion 92 is formed in a perforated disk shape that extends radially outward from one axial end portion of the lid inner cylinder portion 91. The lid outer cylinder portion 93 extends in the same direction as the lid inner cylinder portion 91 from the outer peripheral side of the lid substrate portion 92. The fitting convex portion 94 is formed in an annular shape that protrudes radially outward from the same side as the lid substrate portion 92 in the axial direction of the lid outer cylinder portion 93.

The inner peripheral surface of the lid outer cylinder portion 93 has a cylindrical surface portion 96 and an inclined surface portion 97 in order from the lid substrate portion 92 side. The cylindrical surface portion 96 has a constant diameter. The inclined surface portion 97 is connected to the cylindrical surface portion 96, and the outer diameter of the inclined surface portion 97 is formed in an annular shape that increases with distance from the cylindrical surface portion 96 in the axial direction. A cross section of the inclined surface portion 97 including the central axis of the lid member 82 is formed in a substantially arc shape.

The housing main body 83 is formed mainly by cutting, and is formed in a substantially cylindrical shape. An inner annular protrusion 100 that protrudes radially inward is formed on one side of the housing body 83 in the axial direction. A small-diameter cylindrical surface portion 101, an inclined surface portion 102, a large-diameter cylindrical surface portion 103, and a fitting cylindrical surface portion 104 are formed in this order from the one side in the axial direction on the inner peripheral surface of the housing body 83. The small diameter cylindrical surface portion 101 has a constant diameter. The inclined surface portion 102 is connected to the small diameter cylindrical surface portion 101, and the inner surface of the inclined surface portion 102 is formed in an annular shape that increases as the distance from the small diameter cylindrical surface portion 101 increases. The large diameter cylindrical surface portion 103 is connected to the inclined surface portion 102, and the inner diameter of the large diameter cylindrical surface portion 103 is larger than that of the small diameter cylindrical surface portion 101 and has a constant outer diameter. The cross section of the inclined surface portion 102 including the central axis of the housing body 83 is formed in a substantially arc shape. The small diameter cylindrical surface portion 101 and the inclined surface portion 102 are formed on the inner annular protrusion 100. Although the housing main body 83 is described as being cylindrical, the inner peripheral surface of the housing main body 83 is preferably circular in cross section, but the outer peripheral surface of the housing main body 83 may be polygonal or other non-circular cross section. Good.

In such a housing main body 83, the fitting convex portion of the lid member 82 is formed on the fitting cylindrical surface portion 104 in a state where the fitting cylindrical surface portion 104 extends to the end opposite to the axially inner annular protrusion 100. 94 is fitted. Thereafter, a portion of the housing body 83 opposite to the inner annular protrusion 100 in the axial direction with respect to the fitting convex portion 94 is bent radially inward, so that the housing body 83 and the lid member 82 are integrated and the housing 85 is integrated. It becomes. The lid outer cylinder portion 93 of the lid member 82 constitutes an annular small diameter portion projecting radially inward from the large diameter cylindrical surface portion 103 in the housing 85, and an inclined surface portion 97 is formed in this portion. Further, the inner annular protrusion 100 of the housing body 83 forms an annular small-diameter portion that protrudes radially inward from the large-diameter cylindrical surface portion 103 in the housing 85, and an inclined surface portion 102 is formed in this portion. .
The inclined surface portion 97 and the inclined surface portion 102 are disposed so as to face each other in the axial direction.

The free piston 87 is formed mainly by cutting. The free piston 87 has a substantially cylindrical piston cylinder portion 108 and a plate-like piston closing plate portion 109. The piston closing plate portion 109 is formed so as to close one end portion of the piston cylinder portion 108 in the axial direction.
An outer annular projection 110 is formed on the piston cylinder portion 108 at an intermediate position in the axial direction. The outer diameter of the outer annular protrusion 110 is larger than the other part of the piston cylinder portion 108, and the outer annular protrusion 110 is formed in an annular shape protruding radially outward.

On the outer peripheral surface of the piston cylindrical portion 108, in order from the axial piston closing plate portion 109 side, a tapered surface portion 112, a small diameter cylindrical surface portion 113, an inclined surface portion 114, a large diameter cylindrical surface portion 115, an inclined surface portion 116, a small diameter cylindrical surface portion 117 and A tapered surface portion 118 is formed. The inclined surface portion 114, the large diameter cylindrical surface portion 115, and the inclined surface portion 116 are formed on the outer annular protrusion 110.

The outer diameter of the tapered surface portion 112 is small toward the side opposite to the small-diameter cylindrical surface portion 113 in the axial direction, and the tapered surface portion 112 is formed in a tapered shape. The small-diameter cylindrical surface portion 113 is connected to the large-diameter side of the tapered surface portion 112 and has a constant diameter. The inclined surface portion 114 is connected to the small-diameter cylindrical surface portion 113, and the outer diameter of the inclined surface portion 114 increases as it moves away from the small-diameter cylindrical surface portion 113 in the axial direction, and the inclined surface portion 114 is formed in an annular shape. The large-diameter cylindrical surface portion 115 is connected to the large-diameter side of the inclined surface portion 114, and the outer diameter of the large-diameter cylindrical surface portion 115 is larger than that of the small-diameter cylindrical surface portion 113 and has a constant diameter. The cross section of the inclined surface portion 114 including the central axis of the free piston 87 is formed in a substantially arc shape.

The inclined surface portion 116 is connected to the large-diameter cylindrical surface portion 115, and the outer diameter of the inclined surface portion 116 is formed in an annular shape that decreases as the distance from the large-diameter cylindrical surface portion 115 increases. A small-diameter cylindrical surface portion 117 is connected to the small-diameter side of the inclined surface portion 116. The small diameter cylindrical surface portion 117 has the same diameter as the small diameter cylindrical surface portion 113. The tapered surface portion 118 is connected to the small-diameter cylindrical surface portion 117, and is formed in a tapered shape that decreases toward the opposite side to the small-diameter cylindrical surface portion 117 in the axial direction. The cross section of the inclined surface portion 116 including the central axis of the free piston 87 is formed in a substantially arc shape. The outer annular protrusion 110 is formed in a symmetrical shape with respect to a plane passing through the central position in the axial direction. A passage hole 119 is formed in the free piston 87 at a plurality of locations at intervals in the circumferential direction of the free piston 87. The passage hole 119 is formed at a central position in the axial direction of the outer annular protrusion 110, and penetrates the position of the outer annular protrusion 110 of the piston cylinder portion 108 in the radial direction.

The free piston 87 is disposed in the housing 85 such that the piston closing plate 109 is disposed on the inner annular protrusion 100 side in the axial direction. In the state where the free piston 87 is disposed in the housing 85, the large-diameter cylindrical surface portion 115 moves in the axial direction the position of the large-diameter cylindrical surface portion 103 of the housing main body 83. Further, in the state where the free piston 87 is disposed in the housing 85, the tapered surface portion 112 and the small diameter cylindrical surface portion 113 on one side move the position of the small diameter cylindrical surface portion 101 of the housing body 83 in the axial direction. Further, the free piston 87 is disposed in the housing 85, and the small-diameter cylindrical surface portion 117 and the tapered surface portion 118 on the other side move in the axial direction the position of the cylindrical surface portion 96 of the lid outer cylinder portion 93 of the lid member 82. .

In a state where the free piston 87 is disposed in the housing 85, the inclined surface portion 102 of the housing main body 83 and the inclined surface portion 114 of the free piston 87 overlap each other in the radial direction. Therefore, the inclined surface portion 102 of the housing main body 83 and the inclined surface portion 114 of the free piston 87 face each other in the moving direction of the free piston 87. In addition, the inclined surface portion 97 of the lid outer cylinder portion 93 of the lid member 82 and the inclined surface portion 116 of the free piston 87 overlap each other in the radial direction. Therefore, the inclined surface portion 97 of the lid member 82 and the inclined surface portion 116 of the free piston 87 face each other in the moving direction of the free piston 87.

An O-ring 89 (the natural state is shown in FIG. 2) is arranged between the small diameter cylindrical surface portion 113 and the inclined surface portion 114 of the free piston 87 and the inclined surface portion 102 and the large diameter cylindrical surface portion 103 of the housing body 83. Yes. In other words, the O-ring 89 is disposed between the outer annular protrusion 110 of the free piston 87 and the inner annular protrusion 100 of the housing 85. When the O-ring 89 is in a natural state, a cross section of the O-ring 89 including the central axis is formed in a circular shape. When the O-ring 89 is in a natural state, the inner diameter of the O-ring 89 is smaller than the outer diameter of the small-diameter cylindrical surface portion 113 of the free piston 87, and the outer diameter of the O-ring 89 is the inner diameter of the large-diameter cylindrical surface portion 103 of the housing body 83. Bigger than. That is, the O-ring 89 is fitted to both the free piston 87 and the housing 85 with tightening margins in these radial directions.

Further, an O-ring 88 (the natural state is shown in FIG. 2) is disposed between the large-diameter cylindrical surface portion 103 and the inclined surface portion 97 of the housing 85 and the inclined surface portion 116 and the small-diameter cylindrical surface portion 117 of the free piston 87. . In other words, the O-ring 88 is disposed between the outer annular protrusion 110 of the free piston 87 and the lid outer cylinder portion 93 of the housing 85. When the O-ring 88 is in a natural state, a cross section of the O-ring 88 including the central axis is formed in a circular shape. When the O-ring 88 is in a natural state, the inner diameter of the O-ring 88 is smaller than the outer diameter of the small-diameter cylindrical surface portion 117 of the free piston 87, and the outer diameter of the O-ring 88 is larger than the inner diameter of the large-diameter cylindrical surface portion 103 of the housing 85. Is also big. That is, the O-ring 88 is also fitted to both the free piston 87 and the housing 85 with an allowance in the radial direction.

Both the O-rings 88 and 89 are common parts having the same size, and urge the free piston 87 so as to hold the free piston 87 in the housing 85 at a predetermined neutral position in the axial direction. At the same time, the O-rings 88 and 89 allow the free piston 87 to move on both sides in the axial direction with respect to the housing 85 by elastic deformation.

In the free piston 87, the O-ring 88 contacts the small diameter cylindrical surface portion 117 and the inclined surface portion 116. Of the small diameter cylindrical surface portion 117 and the inclined surface portion 116, the inclined surface portion 116 is inclined with respect to the moving direction of the free piston 87. In the housing 85, the O-ring 88 is in contact with the large diameter cylindrical surface portion 103 and the inclined surface portion 97 of the housing 85. Of the large-diameter cylindrical surface portion 103 and the inclined surface portion 97, the inclined surface portion 97 is a free piston 8.
7 is inclined with respect to the moving direction.

In other words, the outer annular protrusion 110 is provided on the outer peripheral portion of the free piston 87, and both axial surfaces of the outer annular protrusion 110 constitute an inclined surface portion 114 and an inclined surface portion 116. In addition, an inner annular protrusion 100 having an inclined surface portion 102 and a lid outer cylinder portion 93 having an inclined surface portion 97 are provided at positions on both sides of the outer annular protrusion 110 on the inner periphery of the housing 85. Further, an O-ring 89 and an O-ring 88 are provided between the outer annular protrusion 110 and the inner annular protrusion 100 and the lid outer cylinder portion 93, respectively.

When assembling the damping force variable mechanism 58, for example, the O-ring 89 is inserted into the housing body 83 up to the position of the inclined surface portion 102. A free piston 87 is fitted inside the housing main body 83 and the O-ring 89. At that time, the large-diameter cylindrical surface portion 115 of the free piston 87 is guided to the large-diameter cylindrical surface portion 103 of the housing main body 83, and then the tapered surface portion 112 starts from the small-diameter side from the O-ring 89 and the small-diameter cylindrical surface portion 101 of the housing main body 83. Inserted into. Next, the O-ring 88 is inserted between the housing main body 83 and the free piston 87 up to the position of the inclined surface portion 116. Then, the lid member 82 is fitted into the housing body 83 and the housing body 83 is crimped. The damping force variable mechanism 58 assembled in advance in this way is attached by screwing the female screw 81 into the male screw 80 of the mounting shaft portion 40 of the piston rod 8. At that time, the lid substrate portion 92 of the housing 85 comes into contact with the valve regulating member 77a. The outer diameter of the damping force variable mechanism 58, that is, the outer diameter of the housing 85 is set to be smaller than the inner diameter of the inner cylinder 2 so as not to cause flow resistance.

The piston rod 8 and the piston 9 are formed with a rod passage 57, an axial passage 265, a plate-like member passage 70, and a piston passage 261, and a flow passage 270 that always communicates with the flow passage 50a and the chamber 11. ing. In the housing 85, an in-housing passage 121 that is always in communication with the flow passage 270 is formed. The flow passage 270 and the in-housing passage 121 constitute a rod side passage 122. Therefore, the housing 85 has an in-housing passage 121 as a part of the rod-side passage 122 formed therein. In the flow passage 270 constituted by the rod internal passage 57, the axial passage 265, the plate member internal passage 70, the piston internal passage 261, and the flow passage 50a, the parallel plate-like member internal passage 70 and piston internal passage 261 are provided. Orifice. The rod side passage 122 communicates with the chamber 11 that is one of the chamber 11 and the chamber 12 in the inner cylinder 2. In the rod side passage 122, when the pressure of the chamber 11 rises due to the movement of the piston 9 toward the chamber 11, the oil liquid flows out from the chamber 11. That is, as the piston 9 moves toward the chamber 11, the oil liquid flows out from the chamber 11 to the above-described flow passage 50 a and the rod-side passage 122 that is branched from the flow passage 50 a.

The in-housing passage 121 includes a rod chamber side passage portion 123 communicating with the chamber 11 on the piston rod 8 side and a bottom chamber side passage portion communicating with the bottom chamber 12 by the O-ring 89, the free piston 87 and the housing 85. 124. The rod chamber side passage portion 123 includes a chamber 125, a passage hole 119, and a chamber 126. The chamber 125 is surrounded by the lid member 82, the free piston 87, and the O-ring 88, and the in-rod passage 57 is opened.
The passage hole 119 is formed in the free piston 87, and one end of the passage hole 119 opens into the chamber 125. The chamber 126 is surrounded by a housing main body 83, an O-ring 88, an O-ring 89, and a free piston 87, and the other end of the passage hole 119 is opened. The bottom chamber side passage portion 124 is configured by a portion surrounded by the inner annular protrusion 100 side of the housing body 83, the O-ring 89, and the free piston 87.

When the piston 9 moves to the chamber 11 side in the extension stroke, the oil liquid in the chamber 11 flows into the flow passage 270 and the rod chamber side passage portion 123. As a result, the free piston 87 moves to the opposite side of the cover member 82 in the axial direction with respect to the housing 85 while discharging the oil in the bottom chamber side passage portion 124 to the chamber 12. At that time, one O-ring 89 provided between the free piston 87 and the housing 85 includes an inclined surface portion 114 of the outer annular protrusion 110 located between the O-rings 88 and 89 on the outer peripheral portion of the free piston 87, and The inner surface of the housing 85 abuts against the inclined surface portion 102 of the inner annular protrusion 100 and is sandwiched between them to be elastically deformed. That is, this one O-ring 89 generates an elastic force with respect to the movement of the free piston 87 to one side during the extension stroke.

When the piston 9 moves to the chamber 12 side in the contraction stroke, the oil liquid in the chamber 12 presses the free piston 87. Then, the free piston 87 moves toward the lid member 82 in the axial direction with respect to the housing 85 while injecting oil into the bottom chamber side passage portion 124. At this time, the other O-ring 88 provided between the free piston 87 and the housing 85 is connected to the inclined surface portion 116 of the outer annular projection 110 on the outer peripheral portion of the free piston 87 and the outer cover of the inner peripheral portion of the housing 85. It abuts against the inclined surface portion 97 of the cylindrical portion 93 and is sandwiched between them to be elastically deformed. That is, the other O-ring 88 generates an elastic force with respect to the movement of the free piston 87 to the other during the contraction stroke.

Next, the operation of the shock absorber 1 described above will be described.

In the extension stroke in which the piston rod 8 moves to the extension side, the oil liquid flows from the chamber 11 to the chamber 12 through the flow passage 50a. When the piston speed is in a very low speed region, the oil introduced into the flow passage 50a from the chamber 11 is basically a constant opening formed between the valve seat 71a and the disc valve 75a contacting the valve seat 71a. Flows into the chamber 12 through the fixed orifice 78a, and a damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed) is generated. When the piston speed increases and reaches a low speed region, the oil introduced from the chamber 11 into the flow passage 50a basically passes between the disc valve 75a and the valve seat 71a while opening the disc valve 75a. It will flow into the chamber 12. For this reason, a damping force having a valve characteristic (a damping force is substantially proportional to the piston speed) is generated.

In the contraction stroke in which the piston rod 8 moves to the contraction side, the oil liquid flows from the chamber 12 to the chamber 11 through the flow passage 50b. When the piston speed is in a very low speed range, the oil introduced from the chamber 12 into the flow passage 50b is basically a constant opening formed between the valve seat 71b and the disc valve 75b that contacts the valve seat 71b. In this case, a damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed) is generated. When the piston speed increases and reaches a low speed region, the oil introduced from the chamber 12 into the flow passage 50b basically passes between the disc valve 75b and the valve seat 71b while opening the disc valve 75b. It flows into the chamber 11. For this reason, a damping force having a valve characteristic (a damping force is substantially proportional to the piston speed) is generated.

Here, when the piston speed is low, that is, the region where the frequency in the very low speed region (for example, 0.05 m / s) is relatively high (for example, 7 Hz or more) is, for example, vibration caused by unevenness on the fine surface of the road surface. In such a situation, it is preferable to reduce the damping force. Similarly, even when the piston speed is low, the region where the frequency is relatively low (for example, 2 Hz or less) is vibration such as wobbling caused by the roll of the vehicle body. In such a situation, the damping force Is preferable.

Correspondingly, the damping force variable mechanism 58 described above makes the damping force variable according to the frequency even when the piston speed is low as well. That is, when the piston speed is low and the frequency of the reciprocating motion of the piston 9 increases, the pressure in the chamber 11 increases in the extension stroke, and the flow passage 50a, the piston passage 261, the plate member passage 70, While introducing the oil liquid from the chamber 11 to the rod chamber side passage portion 123 of the housing internal passage 121 of the damping force varying mechanism 58 via the flow passage 270 constituted by the axial passage 265 and the rod internal passage 57, the fluid is free. The piston 87 moves to the axial chamber 12 side relative to the housing 85 against the urging force of the O-ring 89 on the axial chamber 12 side. As the free piston 87 moves to the chamber 12 side in the axial direction in this way, the oil liquid is introduced from the chamber 11 into the in-housing passage 121 and is introduced from the chamber 11 into the flow passage 50a and passes through the damping force generation mechanism 51a. The flow rate of the oil flowing into the chamber 12 is reduced. Thereby, a damping force falls. At that time, the amount of the oil flowing into the damping force variable mechanism 58 is controlled by the combined throttling effect of the plate member passage 70 and the piston passage 261 in parallel with the flow passage 270.

Next, in the contraction stroke, the pressure in the chamber 12 increases, so that the flow passage 270 including the rod inner passage 57, the axial passage 265, the plate member inner passage 70, and the piston inner passage 261 of the piston rod 8; , While the oil liquid is discharged from the rod chamber side passage portion 123 of the in-housing passage 121 of the damping force varying mechanism 58 to the chamber 11 through the flow passage 50a, the free movement that has been moved to the axial chamber 12 side until then. The piston 87 moves toward the axial chamber 11 side relative to the housing 85 against the urging force of the O-ring 88 on the axial chamber 11 side. As the free piston 87 moves to the chamber 11 side in the axial direction in this way, the volume of the chamber 12 is expanded, and the oil that is introduced from the chamber 12 into the flow passage 50b and flows into the chamber 11 through the damping force generation mechanism 51b. Liquid flow decreases. Thereby, a damping force falls. Also in this case, the amount of oil discharged from the damping force varying mechanism 58 is controlled by the combined throttling effect of the plate member internal passage 70 and the piston internal passage 261 in parallel with the flow passage 270.

In the region where the frequency of the piston 9 is high, the frequency of movement of the free piston 87 also follows and increases. As a result, the oil liquid flows from the chamber 11 to the rod chamber side passage portion 123 of the in-housing passage 121 at each expansion stroke, and the volume of the chamber 12 is increased by the movement of the free piston 87 at each contraction stroke. Thus, the damping force is maintained in a lowered state.

On the other hand, when the piston speed is low and the frequency of the piston 9 decreases, the frequency of movement of the free piston 87 also decreases. For this reason, although oil liquid flows from the chamber 11 to the rod chamber side passage portion 123 of the in-housing passage 121 at the initial stage of the extension stroke, the free piston 87 then compresses the O-ring 89 to axially move with respect to the housing 85. Since the oil liquid does not flow from the chamber 11 to the rod chamber side passage portion 123 of the in-housing passage 121, the fluid is introduced from the chamber 11 into the flow passage 50a and passes through the damping force generation mechanism 51a. Therefore, the flow rate of the oil flowing through the cylinder does not decrease, and the damping force increases.

Next, even in the contraction stroke, the volume of the chamber 12 is initially increased by the movement of the free piston 87 with respect to the housing 85, but thereafter the free piston 87 compresses the O-ring 88 to the housing 85. Stops on the axial chamber 11 side and does not affect the volume of the chamber 12, so that the flow rate of the oil liquid introduced from the chamber 12 into the flow passage 50b and passing through the damping force generation mechanism 51b into the chamber 11 is not reduced. Thus, the damping force is increased.

The shock absorber described in Patent Document 1 has a configuration in which the damping force variable mechanism and the upper chamber communicate with each other through a communication path. In this shock absorber, tuning can be performed by changing the passage area of the communication passage, but there is a demand to increase the degree of freedom.

On the other hand, in the present embodiment, a piston internal passage 261 that connects the through hole 211 and the communication passage 212 is formed on the coupling surface 210 of one of the two piston bodies 201 and 202. The plate-like member inner passage 70 that connects the through hole 211 and the communication passage 212 is formed in the plate-like member 76 a provided in contact with the non-coupling surface 215 of the piston body 201. As described above, since the piston passage 261 and the plate-like member passage 70 are provided in parallel, the degree of tuning can be increased.

For example, a shock absorber in which a plate-like member internal passage 70 is provided in the plate-like member 76a and the through-hole 211 of the piston body 201 and the communication passage 212 are communicated only with the plate-like member internal passage 70 is used for a larger vehicle. However, the degree of freedom in increasing the flow rate is low from the viewpoint of mass productivity including the press formability of the plate-like member 76a. . On the other hand, by providing the piston inner passage 261 in parallel with the plate-like member passage 70 on the coupling surface 210 of the piston body 201 so as to communicate the through hole 211 and the communication passage 212, the degree of freedom in increasing the flow rate is increased. be able to. In this case, if the flow passage area of the piston passage 261 is fixed and the flow passage area of the plate member passage 70 is changed by exchanging the plate member 76a, a variety of variations can be handled at a relatively low cost. Increases the nature. In addition, since the expansion of the flow path area of the plate-like member inner passage 70 can be suppressed, it is possible to reduce the piston side pressure when the plate-like member 76a is clamped, resulting in variations in damping force due to buckling and the like. Can be suppressed.

In order to restrict the relative rotation, the coupling surfaces 210 and 230 of the piston bodies 201 and 202 are provided with a plurality of engaging portions 251 having a concave portion 241 and a convex portion 221, but the intra-piston passage 261 is adjacent. Since it is provided between the matching engaging portions 251, these can be arranged efficiently.

Since the rod inner passage 57 communicating with the piston inner passage 261 is provided in the piston rod 8, the rod inner passage 57 can be arranged efficiently.

Since the axial passage 265 that communicates the piston passage 261 and the plate-like member passage 70 is provided on the inner peripheral side of the piston body 201, the axial passage 265 can be arranged efficiently.

One side surface of the plate-like member 76a contacts the non-coupling surface 215 of the piston body 201, the other side surface of the plate-like member 76a contacts the disc valve 75a, and the outer diameter of the plate-like member 76a is larger than the outer diameter of the valve seat 71a. Therefore, the plate-shaped member passage 70 can be efficiently arranged.

In the first embodiment described above, the case where the piston inner passage 261 that connects the through hole 211 and the communication passage 212 is formed on the coupling surface 210 of the piston body 201 has been described as an example. 230 may form an in-piston communication path that allows the through-hole 231 and the communication path 232 to communicate with each other, or may form an in-piston communication path on the coupling surfaces 210 and 230 of both piston bodies 201 and 202. That is, it is only necessary that an in-piston communication path that connects the through hole and the communication path is formed on at least one coupling surface of the piston bodies 201 and 202.

In the first embodiment described above, the plate-like member inner passage 70 that connects the through hole 211 and the communication passage 212 is provided in the plate-like member 76 a provided in contact with the non-coupling surface 215 of the piston body 201. Although the case has been described as an example, a groove may be formed in the non-coupling surface 215 of the piston body 201 to provide a communication path that connects the through hole 211 and the communication path 212, and the non-coupling surface 215 of the piston body 201 The disk valve 75a may be brought into contact with the disk valve 75a, and a communication path that connects the through hole 211 and the communication path 212 may be provided in the disk valve 75a. Similarly, the plate-like member 76b provided in contact with the non-coupling surface 235 of the piston body 202 may be provided with a plate-like member communication path that connects the through hole 231 and the communication path 232. A groove may be formed in the non-coupling surface 235 so as to provide a communication path that allows the through hole 231 and the communication path 232 to communicate with each other, and the non-coupling surface 235 of the piston body 202 and the disk valve 75b are brought into contact with each other. You may provide the communicating path which connects the through-hole 231 and the communicating path 232 to the valve | bulb 75b.

Further, in the first embodiment described above, the rod inner passage 57 is formed in the piston rod 8 by the passage holes 55 and 56. However, a groove extending in the axial direction is formed in the outer peripheral portion of the piston rod 8 to form the rod inner passage. Also good.
In the first embodiment described above, an example is shown in which the frequency sensing unit is combined with a frequency sensing unit that makes the damping force variable without being controlled from the outside depending on the frequency (vibration state). You may combine with the position sensitive part which makes damping force variable without being controlled, and the damping force adjustment mechanism which makes damping force variable by controlling from the outside.

The first aspect of the above embodiment includes a piston that is slidably provided in a cylinder in which a fluid is sealed, and that has one end connected to a piston rod that extends to the outside of the cylinder. Each of the piston bodies is provided with a through-hole into which the piston rod is inserted and a plurality of extending and contracting communication passages. An annular valve seat is formed on the non-coupling surface so that the extending communication passage is on the inner peripheral side and the contraction-side communication passage is on the outer peripheral side. An annular valve seat is formed so that the communication path on the side is the inner peripheral side and the communication path on the extension side is the outer peripheral side, and the non-bonding surfaces of the one and the other piston bodies are in contact with the valve seat Disc valve is provided At least a first passage that connects the through hole and the communication passage is formed on the coupling surface of the one piston body, and is in contact with the non-coupling surface or the non-coupling surface of the one piston body. A plate-like member or the disc valve provided is provided with a second passage that connects the through hole and the communication passage. Thus, since it has the 1st channel and the 2nd channel, the freedom degree of tuning can be raised.

Further, the second aspect is the first aspect, wherein a rotation restricting means for restricting the relative rotation of each piston body is provided, and the rotation restricting means is provided on a coupling surface of the piston bodies. It is a plurality of engaging parts which have a crevice and a convex part, and the 1st passage is provided between a plurality of adjacent engaging parts. Since a 1st channel | path is provided between the some engaging parts adjacent, these can be arrange | positioned efficiently.

Further, the third aspect is that, in the first or second aspect, since the piston rod is provided with a third passage communicating with the first passage, the third passage is efficiently arranged. Can do.

Further, a fourth aspect is the first aspect according to any one of the first to third aspects, wherein the first passage and the second passage communicate with each other on the inner peripheral side of the one piston body. Since the passage is provided, the fourth passage can be efficiently arranged.

According to a fifth aspect, in any one of the first to fourth aspects, the plate-like member has one side abutting against the non-coupling surface of the one piston body and the other side abutting against the disc valve. Since the outer diameter is smaller than that of the valve seat, the second passage can be arranged efficiently.
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment and its modification. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention.
Further, the present invention is not limited by the above description, and is limited only by the appended claims.

The shock absorber can increase the degree of tuning freedom.

4 Cylinder 8 Piston rod 9 Piston 57 Rod passage (third passage)
70 Plate-shaped member passage (second passage)
71a, 71b Valve seat 75a, 75b Disc valve 76a Plate member 201, 202 Piston body 210, 230 Connection surface 211, 231 Through hole 212, 232 Expansion side communication path 213, 233 Contraction side communication path 215, 235 Non-connection Surface 251 engaging portion (rotation restricting means)
261 Piston passage (first passage)
265 Axial passage (fourth passage)

Claims (5)

A piston that is slidably provided in a cylinder in which a fluid is sealed, and that has one end connected to a piston rod that extends to the outside of the cylinder;
The piston has two piston bodies;
Each piston body is provided with a through hole into which the piston rod is inserted and a plurality of extending and contracting communication paths,
An annular valve seat is formed on the non-coupling surface of one piston body of the piston bodies so that the extension side communication passage is on the inner peripheral side and the contraction side communication passage is on the outer peripheral side. An annular valve seat is formed on the non-coupling surface of the piston body such that the communication path on the contraction side is on the inner peripheral side and the communication path on the extension side is on the outer peripheral side,
A disc valve that contacts the valve seat is provided on the non-coupling surface of the one and the other piston bodies,
A first passage that communicates the through hole and the communication passage is formed at least on the coupling surface of the one piston body, and is provided in contact with the non-coupling surface or the non-coupling surface of the one piston body. A shock absorber in which a plate-like member or the disc valve is formed with a second passage that connects the through hole and the communication passage. A rotation restricting means for restricting relative rotation of each piston body is provided,
The rotation restricting means is a plurality of engaging portions having concave and convex portions provided on the coupling surfaces of the piston bodies,
The shock absorber according to claim 1, wherein the first passage is provided between the plurality of adjacent engaging portions. The shock absorber according to claim 1 or 2, wherein the piston rod is provided with a third passage communicating with the first passage. The shock absorber according to any one of claims 1 to 3, wherein a fourth passage that communicates the first passage and the second passage is provided on an inner peripheral side of the one piston body. 5. The plate-like member according to claim 1, wherein one side surface of the plate-shaped member is in contact with a non-bonding surface of the one piston body, the other side surface is in contact with the disk valve, and an outer diameter is smaller than that of the valve seat. A shock absorber according to claim 1.

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