JP2014167337A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber with improved durability capable of obtaining stable attenuation performance over a longer period of time.SOLUTION: A shock absorber includes: an inner seat part 35 and an outer seat part 36 having different diameters; and a disk valve 41 attachable to and detachable from the inner seat part 35 and the outer seat part 36. Radial widths W1 and W2 of the inner seat part 35 and the outer seat part 36 are different from each other so as to equalize the degree of decrease in height due to the progress of wear of the inner seat part 35 and the outer seat part 36, thus leading to stable attenuation performance over a longer period of time and improved durability.

Description

  The present invention relates to a shock absorber.

  The shock absorber piston has a seat portion on the inner and outer peripheral sides of the piston port that divides the inside of the cylinder into two chambers, and a disc valve is attached to and detached from these seat portions. Are equal in width in the radial direction (see, for example, Patent Document 1).

JP-A-11-44335

  When viewed from the long term, the disc valve is worn out in the seat part by being seated and removed, or repeatedly moving in the radial direction with slight clearance. The progress of such wear differs between the inner seat portion and the outer seat portion. In the above shock absorber, the inner sheet portion and the outer sheet portion have the same radial width, and therefore, when used for a long period of time, the degree of progress of wear may become uneven. there were. When such non-uniformity occurs, the adhesion between the disc valve and the seat portion deteriorates, the working fluid leaks from the gap between the disc valve and the seat portion, and the damping performance may change.

  Accordingly, an object of the present invention is to provide a shock absorber capable of obtaining a stable attenuation performance in the long term.

  In order to achieve the above object, in the present invention, the radial widths of the inner sheet portion and the outer sheet portion are varied.

  According to the present invention, stable attenuation performance can be obtained for a long period of time, and durability can be improved.

It is a fragmentary sectional view showing a buffer concerning one embodiment of the present invention. It is an expanded sectional view showing the important section of the base valve of the buffer concerning one embodiment of the present invention. It is an expanded sectional view showing an important section of a piston of a buffer concerning one embodiment of the present invention.

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

  A shock absorber 11 according to this embodiment shown in FIG. 1 is used in a suspension device for a vehicle such as an automobile or a railway vehicle. The shock absorber 11 is arranged on a bottomed cylindrical cylinder 12, a central axis of the cylinder 12, one end in the axial direction is inserted into the cylinder 12, and the other end in the axial direction is the opening side of the cylinder 12 (upper side in FIG. 1). ) And the piston rod 14 extending to the outside. The shock absorber 11 is connected to one end of the piston rod 14 and is slidably fitted into the cylinder 12 so as to partition the inside of the cylinder 12 into two chambers, a chamber 16 and a bottom chamber 17. And a rod guide 19 provided on the opening side of the cylinder 12 for guiding the piston rod 14. Although not shown, an oil seal that seals the gap between the cylinder 12 and the piston rod 14 is provided on the opposite side of the rod guide 19 from the piston 18. Further, the shock absorber 11 is disposed on the bottom side (lower side in FIG. 1) of the piston 12 of the cylinder 12 and divides the inside of the cylinder 12 into two chambers of the chamber 17 and the chamber 21 on the bottom side. 22. The chambers 16, 17, and 21 in the cylinder 12 are filled with working fluid such as oil and gas.

  The base valve 22 has a base body 25 that is fitted and fixed to the cylinder 12. The base body 25 has a central shaft portion 26 and a flange portion 27 that extends radially outward from the central shaft portion 26, and is fitted to the cylinder 12 at the flange portion 27. The central shaft portion 26 is closer to the chamber 17 side than the flange portion 27 and sequentially from the flange portion 27 side, the guide shaft portion 28, the large diameter fitting shaft portion 29 having a smaller diameter than the guide shaft portion 28, and the large diameter fitting shaft portion 29. A smaller-diameter fitting shaft portion 30 having a smaller diameter and a locking shaft portion 31 having a larger diameter than the small-diameter fitting shaft portion 30 are provided.

  The flange portion 27 has an inner sheet portion 35 projecting toward the chamber 17 side in the axial direction with a larger diameter than the guide shaft portion 28 on the end surface on the chamber 17 side, and an axial chamber having a larger diameter than the inner sheet portion 35. An outer sheet portion 36 protruding to the 17 side is formed. An annular ring groove 37 and a passage hole 38 that penetrates the base body 25 at the bottom position of the ring groove 37 are formed between the inner sheet portion 35 and the outer sheet portion 36. A plurality of passage holes 38 are formed at equal intervals in the circumferential direction of the base body 25. The annular groove 37 and the plurality of passage holes 38 constitute a passage 39 that allows communication between the chambers 17 and 21.

  The inner seat portion 35 and the outer seat portion 36 are concentric with the central axis of the base body 25 as the center, and have different diameters. The sheet surface 35a at the distal end of the inner sheet portion 35 and the sheet surface 36a at the distal end of the outer sheet portion 36 are disposed on a plane orthogonal to the central axis of the base body 25, and the height positions in the axial direction coincide with each other. Yes.

  A perforated disk-shaped disc valve 41 is slidably fitted to the guide shaft portion 28 of the central shaft portion 26. The disc valve 41 has a flat plate shape extending in the direction perpendicular to the axis, and is in contact with the seat surface 35a of the inner seat portion 35 and the seat surface 36a of the outer seat portion 36 on the seating surface 41a on one side in the axial direction. 39 is closed. At that time, the disc valve 41 contacts the seat surface 35a of the inner seat portion 35 on the inner peripheral side of the seating surface 41a, and contacts the seat surface 36a of the outer seat portion 36 on the outer peripheral side of the seating surface 41a. As a result, the disc valve 41 blocks communication between the chambers 17 and 21. The disc valve 41 slides in the guide shaft portion 28 in the axial direction to open the passage 39 away from the seat surface 35a of the inner seat portion 35 and the seat surface 36a of the outer seat portion 36. Thereby, the chambers 17 and 21 are communicated with each other. That is, the disc valve 41 can be separated from the inner seat portion 35 and the outer seat portion 36. The disc valve 41 restricts the flow of the working fluid in the reverse direction while allowing the flow of the working fluid from the chamber 21 to the chamber 17 flowing through the passage 39.

  A retainer 46 having a cylindrical portion 44 and a flange portion 45 that extends radially from one axial end of the cylindrical portion 44 is fitted to the large-diameter fitting shaft portion 29 of the central shaft portion 26. The retainer 46 is oriented so that the flange portion 45 is located on the opposite side of the disc valve 41. In this state, the stopper ring 47 mounted on the small diameter fitting shaft portion 30 and the guide shaft portion 28 are fitted with a large diameter. It is sandwiched between the end surface on the side of the shaft portion 29. Thereby, the retainer 46 is attached to the base body 25 so as not to move in the axial direction.

  A spring member 50 is interposed between the flange portion 45 of the retainer 46 and the disc valve 41 so that the tubular portion 44 of the retainer 46 is inserted inside. The spring member 50 is a coil spring, and abuts against a pressed surface 41b opposite to the seating surface 41a of the disc valve 41 so that the disc valve 41 is seated in the seating direction on the inner seat portion 35 and the outer seat portion 36. Press. The spring member 50 has a conical shape in order to secure the stroke of the disc valve 41 while shortening the axial distance between the retainer 46 and the disc valve 41, and the pressed surface 41 b of the disc valve 41 on the large diameter side. Press the outer peripheral side. That is, the spring member 50 is closer to the outer seat portion 36 than the inner seat portion 35 in the radial direction at the position pressed against the disc valve 41.

  In the present embodiment, as shown in FIG. 2, the inner sheet portion 35 and the outer sheet portion 36 have different radial widths W <b> 1 and W <b> 2, specifically, the radial direction of the inner sheet portion 35. The width W2 in the radial direction of the outer sheet portion 36 is formed wider than the width W1.

  As shown in FIG. 1, the disc valve 41 is separated from the seat surface 35 a of the inner seat portion 35 and the seat surface 36 a of the outer seat portion 36 when the pressure in the chamber 17 is equal to or higher than the pressure in the chamber 21. In other words, the passage 39 is kept closed. On the other hand, for example, the piston rod 14 moves in the extending direction to increase the amount of protrusion from the cylinder 12, and the pressure of the chamber 17 is lowered by the movement of the piston 18 accompanying this, and the pressure of the chamber 21 is higher than the pressure of the chamber 17. When it becomes higher than the predetermined value, the disc valve 41 moves on the guide shaft portion 28 against the urging force of the spring member 50, and is separated from the inner seat portion 35 and the outer seat portion 36 to open the passage 39. The chambers 17 and 21 are connected. Thereby, the working fluid flows from the chamber 17 to the chamber 21.

  The piston rod 14 includes a main shaft portion 55 inserted through the rod guide 19, an intermediate shaft portion 56 having a smaller diameter than the main shaft portion 55, a guide shaft portion 57 having a smaller diameter than the intermediate shaft portion 56, and a smaller diameter than the guide shaft portion 57. The fitting shaft portion 58 and the end screw shaft portion 59 are provided. An annular groove 60 having a smaller diameter than the fitting shaft portion 58 is formed between the guide shaft portion 57 and the fitting shaft portion 58, and between the fitting shaft portion 58 and the screw shaft portion 59, An annular groove 61 having a smaller diameter than these is formed.

  The piston 18 has a perforated disk shape in which a small-diameter hole 65 is formed on one side in the axial direction, and a large-diameter hole 66 having a larger diameter than the small-diameter hole 65 is formed on the other side from the intermediate portion in the axial direction. There is no. The piston 18 fits the fitting shaft portion 58 of the piston rod 14 into the small-diameter hole 65, and in this state, the piston rod is engaged with the nut 67 that is screwed into the screw shaft portion 59 located in the large-diameter hole 66. 14 is attached. At that time, the end surface on the fitting shaft portion 58 side of the guide shaft portion 57 of the piston rod 14 and the nut 67 sandwich the piston 18. In this way, the piston 18 is integrally attached to the piston rod 14 with the central axis coincident.

  The piston 18 includes an inner sheet portion 75 projecting toward the axial chamber 16 side having a larger diameter than the guide shaft portion 57 and an axial chamber 16 having a larger diameter than the inner sheet portion 75 on the end surface on the chamber 16 side. An outer sheet portion 76 protruding to the side is formed. Between the inner sheet portion 75 and the outer sheet portion 76, an annular ring groove 77 and a passage hole 78 that penetrates the piston 18 at the bottom position of the ring groove 77 are formed. The passage hole 78 has one end opened at the bottom of the annular groove 77 and the other end opened at the bottom of the large-diameter hole 66. A plurality of passage holes 78 are formed at equal intervals in the circumferential direction of the piston 18. The annular groove 77 and the plurality of passage holes 78 constitute a passage 79 that allows communication between the chambers 16 and 17.

  The inner sheet portion 75 and the outer sheet portion 76 are concentric with the central axis of the piston 18 as the center, and have different diameters. The sheet surface 75a at the distal end of the inner sheet portion 75 and the sheet surface 76a at the distal end of the outer sheet portion 76 are disposed on a plane orthogonal to the central axis of the piston 18, and the height positions in the axial direction coincide with each other. .

  A perforated disk-shaped disc valve 81 is slidably fitted to the guide shaft portion 57 of the piston rod 14. The disc valve 81 has a flat plate shape along the direction orthogonal to the axis, and in the seating surface 81a on the one side in the axial direction, simultaneously contacts the seat surface 75a of the inner seat portion 75 and the seat surface 76a of the outer seat portion 76. 79 is closed. At that time, in the disc valve 81, the inner peripheral side of the seating surface 81 a contacts the seat surface 75 a of the inner seat portion 75, and the outer peripheral side of the seating surface 81 a contacts the seat surface 76 a of the outer seat portion 76. As a result, the disc valve 81 blocks communication between the chambers 16 and 17. Further, the disc valve 81 slides in the guide shaft portion 57 in the axial direction and opens the passage 79 away from the inner seat portion 75 and the outer seat portion 76. Thereby, the chambers 16 and 17 are communicated with each other. That is, the disk valve 81 can be seated on and away from the inner seat portion 75 and the outer seat portion 76. The disc valve 81 restricts the flow of the working fluid in the reverse direction while allowing the flow of the working fluid from the chamber 17 to the chamber 16 flowing through the passage 79.

  A spring member 90 is interposed between the end surface of the main shaft portion 55 of the piston 18 on the intermediate shaft portion 56 side and the disc valve 81 so that the intermediate shaft portion 56 is inserted inside. The spring member 90 is a coil spring, and contacts the pressed surface 81b opposite to the seating surface 81a of the disc valve 81 so that the disc valve 81 is seated in the seating direction on the inner seat portion 75 and the outer seat portion 76. Press. The spring member 90 has a cylindrical shape with an outer diameter smaller than that of the main shaft portion 55 so as not to interfere with the rod guide 19 when the piston 18 moves to the rod guide 19 side. Press the inner circumference side. That is, the spring member 90 is closer to the inner seat portion 75 than the outer seat portion 76 in the radial direction at the position pressed against the disc valve 81.

  And in this embodiment, as shown in FIG. 3, the outer side sheet | seat part 76 and the inner side sheet | seat part 75 differ in radial width W3, W4. Specifically, the radial direction of the outer side sheet | seat part 76 is shown. The width W4 in the radial direction of the inner sheet portion 75 is wider than the width W3.

  As shown in FIG. 1, the disc valve 81 provided on the piston 18 is not separated from the inner seat portion 75 and the outer seat portion 76 when the pressure in the chamber 16 is equal to or higher than the pressure in the chamber 17. The state where the passage 79 is closed is maintained. On the other hand, for example, when the piston rod 14 moves in the contracting direction to increase the amount of entry into the cylinder 12 and the pressure in the chamber 17 increases and becomes higher than the pressure in the chamber 16 by a predetermined value or more, the disc valve 81 is moved to the spring member 90. It moves on the guide shaft portion 57 against the urging force, and is separated from the inner seat portion 75 and the outer seat portion 76 to open the passage 79 and to communicate between the chambers 16 and 17.

  In the above-described shock absorber 11, when viewed from the long term, the disk valve 41 provided on the base valve 22 is seated and detached, or repeatedly moves in the radial direction with clearance, whereby the inner seat portion 35 and The outer sheet portion 36 may be worn. The pressing position of the spring member 50 to the disc valve 41 is closer to the outer seat portion 36 than the inner seat portion 35 in the radial direction, and the pressing force from the disc valve 41 is greater than the inner seat portion 35 to the outer seat portion 36. Is higher. Therefore, if the radial widths of the inner sheet portion 35 and the outer sheet portion 36 are made equal, the outer sheet portion 36 has a higher surface pressure than the inner sheet portion 35 and wear increases, and the sheet of the outer sheet portion 36 advances. There is a possibility that the height position of the surface 36 a in the axial direction is lower than the sheet surface 35 a of the inner sheet portion 35. Then, even if the disc valve 41 is seated on the inner seat portion 35, a state occurs in which the disc valve 41 cannot be seated on the outer seat portion 36, and the working fluid leaks from the gap between the disc valve 41 and the outer seat portion 36, and the damping force characteristic changes. There is a possibility that.

  On the other hand, in the present embodiment, the inner seat portion 35 and the outer seat portion 36 of the base valve 22 have different radial widths W1, W2. Specifically, the inner seat portion 35 has a radial width. The width W2 in the radial direction of the outer sheet portion 36 is formed wider than W1. Thereby, the surface pressure of the outer sheet part 36 can be lowered, and the degree of reduction in height due to the progress of wear of the inner sheet part 35 and the outer sheet part 36 can be equalized. Therefore, it can suppress that the adhesiveness of the disc valve 41 and the outer seat part 36 deteriorates, and it can suppress that a working fluid leaks from the clearance gap between the disc valve 41 and the outer seat part 36, and a damping performance changes. . Therefore, stable damping performance can be obtained for a long period of time, and durability can be improved.

  Further, when viewed from the long term, the disk valve 81 provided on the piston 18 also moves away and seats or repeatedly moves slightly in the radial direction with a clearance, so that the inner seat portion 75 and the outer seat portion 76 May cause wear. The pressing position of the spring member 90 to the disc valve 81 is closer to the inner seat portion 75 than the outer seat portion 76 in the radial direction, and the pressing force from the disc valve 81 is greater than the outer seat portion 76 to the inner seat portion 75. Is higher. Therefore, if the widths in the radial direction of the inner sheet portion 75 and the outer sheet portion 76 are made equal, the inner sheet portion 75 has a higher surface pressure than the outer sheet portion 76 and wear increases, and the sheet of the inner sheet portion 75 progresses. There is a possibility that the height position of the surface 75 a in the axial direction is lower than the sheet surface 76 a of the outer sheet portion 76. Then, even if the disc valve 81 is seated on the outer seat portion 76, a state where the disc valve 81 cannot be seated on the inner seat portion 75 occurs, the working fluid leaks from the gap between the disc valve 81 and the inner seat portion 75, and the damping force characteristic changes. There is a possibility that.

  On the other hand, in the present embodiment, the outer sheet portion 76 and the inner sheet portion 75 of the piston 18 have different radial widths W3 and W4. Specifically, the outer sheet portion 76 has a radial width W3. The width W4 in the radial direction of the inner sheet portion 75 is wider than that. Thereby, the surface pressure of the inner sheet part 75 can be lowered, and the degree of reduction in height due to the progress of wear of the inner sheet part 75 and the outer sheet part 76 can be equalized. Therefore, it can suppress that the adhesiveness of the disc valve 81 and the inner side seat part 75 deteriorates, and it can suppress that a working fluid leaks from the clearance gap between the disc valve 81 and the inner side seat part 75, and a damping performance changes. . Therefore, stable damping performance can be obtained for a long period of time, and durability can be improved.

  The embodiment described above is a shock absorber having an inner seat portion and an outer seat portion having different diameters, and a disc valve that can be attached to and detached from the inner seat portion and the outer seat portion, and the inner seat portion and the outer seat. The portions are characterized by different radial widths. Thereby, it becomes possible to equalize the progress of wear of the inner sheet portion and the outer sheet portion. Therefore, it is possible to obtain a stable attenuation performance over a long period of time, and it is possible to improve durability.

  And a spring member that presses the disc valve in a seating direction on the inner seat portion and the outer seat portion, and the spring member is configured such that the pressing position on the disc valve is the inner seat portion in a radial direction. The outer sheet portion is closer to the outer sheet portion, and the outer sheet portion is wider in the radial direction than the inner sheet portion. Thereby, the surface pressure of the outer seat portion against which the disc valve is pressed with a large force by the spring member can be reduced. Therefore, the progress of wear of the inner sheet portion and the outer sheet portion can be equalized. Therefore, stable damping performance can be obtained for a long period of time, and durability can be improved.

  And a spring member that presses the disc valve in a seating direction on the inner seat portion and the outer seat portion, and the spring member is configured such that the pressing position on the disc valve is in the radial direction when the outer seat portion is in the radial direction. It is closer to the inner sheet part than the inner sheet part, and the inner sheet part is wider in the radial direction than the outer sheet part. Thereby, the surface pressure of the inner seat portion against which the disc valve is pressed with a large force by the spring member can be reduced. Therefore, the progress of wear of the inner sheet portion and the outer sheet portion can be equalized. Therefore, stable damping performance can be obtained for a long period of time, and durability can be improved.

35,75 Inner seat part 36,76 Outer seat part 41,81 Disc valve 50,90 Spring member W1, W2, W3, W4 Width

Claims (3)

An inner sheet portion and an outer sheet portion having different diameters;
In a shock absorber having a disc valve that can be detachably seated on the inner seat portion and the outer seat portion,
The shock absorber according to claim 1, wherein the inner sheet portion and the outer sheet portion have different radial widths. A spring member that presses the disc valve in the seating direction on the inner seat portion and the outer seat portion;
The spring member is closer to the outer seat portion than the inner seat portion in the radial direction at a position pressed against the disk valve,
The shock absorber according to claim 1, wherein the outer sheet portion has a larger radial width than the inner sheet portion. A spring member that presses the disc valve in the seating direction on the inner seat portion and the outer seat portion;
The spring member is closer to the inner seat portion than the outer seat portion in the radial direction at a position pressed against the disk valve,
The shock absorber according to claim 1, wherein the inner sheet portion has a larger radial width than the outer sheet portion.

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