JP2014190499A - Fluid pressure shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid pressure shock absorber configured to improve quality.SOLUTION: In a fluid pressure shock absorber 1, communication passages 22 for establishing communication between the inside and outside of a cylinder 2 are respectively disposed in a tapered part 27 of a cylinder 2. When a separator tube 20 with seal members 19 and 19 attached thereto is engaged with the outer periphery of the cylinder 2, the seal member 19 close to a rod guide 8 is not brought into contact with the individual communication passages 22. It is therefore avoidable that the seal member 19 is contacted with the individual communication passages 22 so as to be twisted and damaged as in conventional ones. This ensures quality improvement.

Description

  The present invention relates to a fluid pressure shock absorber that generates a damping force by controlling a flow of a working fluid with respect to a stroke of a piston rod.

  In general, a fluid pressure shock absorber mounted on a vehicle suspension device or the like is configured such that a piston having a piston rod connected thereto is slidably fitted in a cylinder in which a working fluid is sealed so that the piston rod strokes. Thus, the flow of fluid generated by the sliding of the piston in the cylinder is controlled by a damping force generation mechanism including an orifice, a disk valve and the like to generate a damping force.

  For example, Patent Document 1 discloses a passage provided on a peripheral wall near the upper end of a cylinder and communicating between the inside and outside of the cylinder, a separator tube disposed on the outer periphery of the cylinder so as to cover the passage, and both axial sides of the passage. A shock absorber is disclosed that includes a seal member that is positioned between the cylinder and the separator tube.

JP 2012-72857 A

  However, in the shock absorber described in Patent Document 1, when the separator tube fitted with the seal member is fitted to the outer periphery of the cylinder, the seal member crosses the passage of the cylinder so that the seal member is twisted or damaged. There was a fear and it was necessary to improve.

  This invention is made | formed in view of this point, and it aims at providing the fluid pressure buffer which quality is improved.

  In order to solve the above-described problems, a fluid pressure shock absorber according to the present invention includes a cylinder in which a working fluid is sealed, a piston slidably fitted in the cylinder, and one end connected to the piston. A piston rod whose other end extends to the outside of the cylinder; a rod guide for guiding the piston rod along the axial direction; a communication path provided in the cylinder for communicating inside and outside the cylinder; A fluid pressure / fluid pressure shock absorber comprising: an outer cylinder fitted on an outer peripheral side; and seal members provided on both sides in the axial direction of the communication path and sealing between the cylinder and the outer cylinder. The communication path is formed at a position where the diameter of the cylinder is smaller than a portion where the seal member abuts and at a non-sliding position of the piston.

  According to the fluid pressure shock absorber according to the present invention, the quality can be improved.

It is sectional drawing of the fluid pressure buffer which concerns on one Embodiment of this invention. It is sectional drawing of the cylinder employ | adopted as the fluid pressure buffer of FIG. It is sectional drawing of the cylinder which concerns on other embodiment.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the fluid pressure shock absorber 1 according to the present embodiment has a double cylinder structure in which an outermost cylinder 3 is provided outside a cylinder 2, and the cylinder 2 and the outermost cylinder 3 are interposed between them. A reservoir 4 is formed. A piston 5 is slidably fitted in the cylinder 2, and the inside of the cylinder 2 is defined by the piston 5 as two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. One end of a piston rod 6 is connected to the piston 5 by a nut 7. The other end of the piston rod 6 passes through the cylinder upper chamber 2 </ b> A, is inserted into the rod guide 8 and the oil seal 9 attached to the upper ends of the cylinder 2 and the outermost cylinder 3, and extends to the outside of the cylinder 2. ing. The piston rod 6 is provided with an annular support member 28 and a stopper member 29 disposed on the rod guide 8 side of the support member 28 at a position between the piston 5 and the rod guide 8. . The stopper member 29 is made of synthetic resin, and is used to alleviate the collision with the rod guide 8 when the piston rod 6 extends at the maximum. A base valve 10 that partitions the cylinder lower chamber 2 </ b> B and the reservoir 4 is provided at the lower end of the cylinder 2.

  The piston 5 is provided with passages 11 and 12 for communicating between the cylinder upper chamber 2A and the cylinder lower chamber 2B. The passage 12 is provided with a check valve 13 that allows only working fluid to flow from the cylinder lower chamber 2B side to the cylinder upper chamber 2A side. On the other hand, the passage 11 is provided with a disk valve 14 that opens when the pressure of the working fluid on the cylinder upper chamber 2A side reaches a predetermined pressure and relieves it to the cylinder lower chamber 2B side.

  The base valve 10 is provided with passages 15 and 16 that allow the cylinder lower chamber 2B and the reservoir 4 to communicate with each other. The passage 15 is provided with a check valve 17 that allows only working fluid to flow from the reservoir 4 side to the cylinder lower chamber 2B side. On the other hand, the passage 16 is provided with a disk valve 18 that opens when the pressure of the working fluid on the cylinder lower chamber 2B side reaches a predetermined pressure and relieves it to the reservoir 4 side. Note that as the working fluid, an oil liquid is sealed in the cylinder 2, and an oil liquid and a gas are sealed in the reservoir 4.

  A separator tube 20 is externally fitted to the cylinder 2 via seal members 19 and 19 disposed at both ends in the axial direction, and an annular passage 21 is formed between the cylinder 2 and the separator tube 20. The separator tube 20 corresponds to an outer cylinder. Referring also to FIG. 2, the cylinder 2 is in contact with each seal member 19 at the time of assembly, and between each large diameter portion 25, 25 disposed at both ends in the axial direction and between each large diameter portion 25, 25. A small-diameter portion 26 that extends in the axial direction and has a smaller diameter than the large-diameter portion 25, and tapered portions 27 and 27 that connect the large-diameter portion 25 and the small-diameter portion 26. The large-diameter portion 25 is formed to have a considerably shorter axial length than the small-diameter portion 26. A plurality of substantially circular communication paths 22 are provided in the taper portion 27 on the rod guide 8 side of the cylinder 2 at intervals in the circumferential direction (in this embodiment, four positions at a pitch of 90 °). These communication passages 22 are respectively provided on the same circumference in the taper portion 27. The cylinder upper chamber 2 </ b> A and the annular passage 21 communicate with each other through these communication passages 22. The piston 5 is slidably fitted in the small diameter portion 26 of the cylinder 2 along the axial direction. As a result, each communication path 22 is provided in a non-sliding portion of the piston 5 of the cylinder 2. A cylindrical connection port 23 is formed in the lower part of the separator tube 20 so as to protrude sideways and open. Further, an opening 24 that is concentric with the connection port 23 and has a larger diameter than the connection port 23 is provided on the side wall of the outermost cylinder 3. A cylindrical case 31 is joined by welding or the like so as to surround the opening 24. A damping force generating mechanism 30 is attached to the case 31.

  In the fluid pressure shock absorber 1 according to the present embodiment, the large-diameter portions 25 and 25 with which the seal members 19 abut each other, and the small-diameter portion 26 extending in the axial direction between the large-diameter portions 25 and 25. In addition, the cylinder 2 including the respective tapered portions 27 and 27 that connect the respective large diameter portions 25 and the small diameter portions 26 is employed. However, as illustrated in FIG. 3, the seal member 19 disposed on the rod guide 8 side includes The large diameter portion 25 to be abutted, the small diameter portion 26a to which the seal member 19 disposed on the base valve 10 side is abutted, the large diameter portion 25 and the small diameter portion 26a are connected, and each communication passage 22 is connected. You may employ | adopt the cylinder 2 which consists of the taper part 27 which has. In that case, it is necessary to reduce the diameter of the base valve 10 side of the cylinder 2. More specifically, since both ends of the cylinder 2 shown in FIG. 1 are large-diameter portions 25, the separator tube 20 is a tube having the same diameter on both the rod guide 8 side and the base valve 10 side. Since the base valve 10 side has no large diameter portion and has a small diameter, the base valve 10 side of the separator tube 20 is used with a diameter reduced to fit into the small diameter portion 26 a of the cylinder 2.

As shown in FIG. 1, the damping force generating mechanism 30 includes a pilot-type main valve 32 and a valve block 35 including a fail valve 33 that operates during a failure, and a solenoid drive that controls the valve opening pressure of the main valve 32. And a solenoid block 37 for operating a pilot valve 36 which is a pressure control valve. A passage member 40 is disposed on one end side of the valve block 35. One end of the passage member 40 is connected to the connection port 23 of the separator tube 20, the other end is inserted into the cylindrical case 31, and the valve block 35 and the solenoid block 37 are combined and integrated to form a case. 31 is inserted.
Then, by energizing the coil 46 of the solenoid block 37, the pilot valve 36 is advanced toward the pilot body 42, and the tip portion is seated on the seat portion of the pilot body 42. Thereby, the valve opening pressure of the pilot valve 36 can be controlled by the energization current to the coil 46 of the solenoid block 37, and the pressure control by the pilot valve 36 can be executed.

The operation of the fluid pressure shock absorber 1 according to this embodiment will be described.
In the fluid pressure shock absorber 1, during the extension stroke of the piston rod 6, the check valve 13 of the piston 5 is closed by the movement of the piston 5 in the cylinder 2, and before the disk valve 14 is opened, the cylinder upper chamber 2 </ b> A is opened. The hydraulic fluid on the side is pressurized, passes through the communication passages 22 and the annular passage 21, and flows from the connection port 23 of the separator tube 20 to the reservoir 4 through the damping force generation mechanism 30.

  At this time, the oil corresponding to the movement of the piston 5 opens the check valve 17 of the base valve 10 from the reservoir 4 and flows into the cylinder lower chamber 2B through the passage 15. When the pressure in the cylinder upper chamber 2A reaches the valve opening pressure of the disk valve 14 of the piston 5, the disk valve 14 is opened, and the pressure in the cylinder upper chamber 2A is relieved to the cylinder lower chamber 2B. Prevent excessive pressure rise of 2A.

  On the other hand, during the contraction stroke of the piston rod 6, the check valve 13 of the piston 5 is opened by the movement of the piston 5 in the cylinder 2, the check valve 17 of the passage 15 of the base valve 10 is closed, and the disk valve 18 is opened. Before the valve, the fluid in the cylinder lower chamber 2B flows into the cylinder upper chamber 2A through the passage 12, and the amount of fluid that has entered the cylinder 2 from the piston rod 6 enters the cylinder 2 from the cylinder upper chamber 2A. It flows to the reservoir 4 from the connection port 23 of the separator tube 20 through the damping force generation mechanism 30 through the same path as that at the time, that is, through each communication path 22 and the annular path 21. When the pressure in the cylinder lower chamber 2B reaches the valve opening pressure of the disk valve 18 of the base valve 10, the disk valve 18 is opened, and the pressure in the cylinder lower chamber 2B is relieved to the reservoir 4, thereby Prevent excessive pressure rise of 2B.

  During the expansion / contraction stroke of the piston rod 6, the damping force generating mechanism 30 has a damping force due to the opening pressure of the orifice passage 43 of the pilot pin 41 and the pilot valve 36 before the main valve 32 is opened (piston speed low speed region). Will occur. Further, after the main valve 32 is opened (piston speed high speed region), a damping force is generated according to the opening of the main valve 32. The damping force can be directly controlled regardless of the piston speed by adjusting the valve opening pressure of the pilot valve 36 by the energization current to the coil 46 of the solenoid block 37. That is, the internal pressure of the back pressure chamber 45 is changed by the valve opening pressure of the pilot valve 36, and the internal pressure of the back pressure chamber 45 acts in the valve closing direction of the main valve 32. Therefore, the valve opening pressure of the pilot valve 36 is controlled. Thus, the valve opening pressure of the main valve 32 can be adjusted at the same time, so that the adjustment range of the damping force characteristic can be widened.

  As described above, in the fluid pressure shock absorber 1 according to the present embodiment, the cylinder 2 includes the large-diameter portions 25 and 25 with which the seal members 19 are in contact, and the large-diameter portions 25 and 25. A small-diameter portion 26 extending in the axial direction and having a diameter smaller than that of the large-diameter portion 25, and tapered portions 27 and 27 connecting the large-diameter portions 25 and the small-diameter portions 26 are formed on the tapered portion 27 on the rod guide 8 side. A plurality of substantially circular communication paths 22 are provided. As a result, when the separator tube 20 fitted with the seal members 19, 19 is fitted to the outer periphery of the cylinder 2, in particular, the seal member 19 on the rod guide 8 side does not come into contact with each communication path 22. It is possible to avoid the seal member 19 from coming into contact with each communication passage 22 and being twisted or damaged. As a result, the quality of the fluid pressure shock absorber 1 can be improved.

  Further, in the fluid pressure shock absorber 1 according to the present embodiment, each communication path 22 is formed in the tapered portion 27 of the cylinder 2, so that when the piston rod 6 extends greatly, each communication path 22 is moved by the stopper member 29. A stable desired damping force characteristic can be obtained without being blocked. Therefore, conventionally, when the stopper member 29 reaches the position of the communication path 22 of the cylinder 2, the plurality of communication paths 22 are formed by shifting the positions in the axial direction so that all the communication paths 22 are not blocked. In contrast to the configuration described above, a plurality of communication passages 22 can be provided on the same circumference of the cylinder 2. As a result, when the communication path 22 is formed in the cylinder 2, it is only necessary to process on the same circumference, so that the processing time can be shortened and the productivity can be improved.

  In the fluid pressure shock absorber 1 according to the present embodiment, the communication path 22 is provided in the tapered portion 27 of the cylinder 2. However, the communication path 22 is not limited to this configuration, and the communication path 22 is not slidable with respect to the piston 5 of the cylinder 2. What is necessary is just to form in the position used as a diameter smaller than the outer diameter of the site | part which the seal member 19 contact | abuts. However, it is preferable to provide the communication path 22 in the taper portion 27 because the axial length of the cylinder 2 can be shortened.

  DESCRIPTION OF SYMBOLS 1 Fluid pressure buffer, 2 Cylinder, 3 Outer cylinder, 4 Reservoir, 5 Piston, 6 Piston rod, 8 Rod guide, 19 Seal member, 20 Separator tube (outer cylinder) 22 Communication path, 25 Large diameter part, 26, 26a Small diameter part, 27 Taper part, 29 Stopper member

Claims (3)

A cylinder filled with a working fluid;
A piston slidably fitted in the cylinder;
A piston rod having one end connected to the piston and the other end extending outside the cylinder;
A rod guide for guiding the piston rod along the axial direction;
A communication path provided in the cylinder for communicating inside and outside the cylinder;
An outer cylinder fitted to the outer peripheral side of the cylinder;
Each of the fluid pressure shock absorbers is provided on both sides in the axial direction of the communication path, and each seal member seals between the cylinder and the outer cylinder,
The fluid pressure shock absorber, wherein the communication path is formed at a position where the diameter of the cylinder is smaller than a portion where the seal member abuts and at a non-sliding position of the piston.   The fluid pressure shock absorber according to claim 1, wherein the piston rod is provided with a stopper member between the piston and the rod guide. The cylinder includes a large diameter portion with which the seal member is abutted, a small diameter portion having a smaller diameter than the large diameter portion, and a tapered portion connecting the large diameter portion and the small diameter portion,
The fluid pressure shock absorber according to claim 1, wherein the communication path is formed in the tapered portion.

Images