JP2006234037A - Shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the durability of a shock absorber by absorbing shock without an accumulator. <P>SOLUTION: Cover parts 13, 16 having rod passing holes 14, 17 are provided at both the ends of a cylindrical case 11, one end of a rod 21 mounted on the cylindrical case 11 is projected from the cylindrical case 11 and made to serve as an operating end 22, and the other end thereof is made to serve as a retreated end 23. A liquid storage chamber 25 for storing liquid L is formed in the cylindrical case 11, and also a piston 31 is arranged in the liquid storage chamber 25 and moved in liquid L with association with the movement of the rod 21. Thereby when the rod 21 is moved, the capacity of the liquid storage chamber 25 is kept constant. Spring force in a direction to project the operating end 22 is applied to the rod 21 by a compression coil spring 34. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shock absorber that reduces the impact force of a moving member when the moving member is stopped.

  In order to relieve the impact force of the moving member when the reciprocating moving member moves to the position of the reciprocating end, a shock absorber, ie, a shock absorber, is used. For example, when an electronic component or the like is moved by a reciprocating table, the reciprocating table is linearly reciprocated by a pneumatic cylinder. When the reciprocating table is moved to the position of the reciprocating end, the cylinder body is reciprocated. The table will collide and stop. Therefore, a shock absorber may be attached to the cylinder body in order to relieve the impact force applied to the cylinder body by the reciprocating table when stopping the reciprocating member.

As a shock absorber used for such applications, a rod is projected from one end of a cylindrical case so that a reciprocating table as a moving member collides with the rod, and the rod reciprocates while moving backward in the cylindrical case. There is a type that absorbs the impact of the moving table (see Patent Document 1). A coil spring that applies a spring force in the protruding direction to the rod is incorporated in the cylindrical case, and a liquid made of silicon oil or the like is enclosed, so that the piston fixed to the rod moves in the liquid by the backward movement of the rod. The piston receives a braking force by the liquid when moving. An accumulator is incorporated in the cylindrical case so as to be positioned outside the rod, and the accumulator is formed of an elastically deformable sponge-like material containing an infinite number of bubbles. The liquid flowing between the inner peripheral surface of the case and moving toward the tip side of the rod volume is contracted and absorbed. When the reciprocating table moves away from the rod, the rod moves forward by the spring force of the coil spring and protrudes from one end of the cylindrical case, so that the liquid returns to the spring side as the accumulator expands.
Japanese Utility Model Publication No. 61-55530

  In a conventional shock absorber in which the rod that the moving member collides is projected from one end side of the cylindrical case, the volume of the liquid storage chamber is the same as the rod moves backward in the cylindrical case. As the volume of the liquid that enters the liquid increases, the liquid is absorbed by the accumulator corresponding to the volume increase. Thus, when the volume in which the rod enters the cylindrical case changes due to the movement of the rod, it is essential to incorporate an accumulator for absorbing the liquid.

  Since the accumulator repeats expansion and contraction every time the shock is absorbed, the durability is lower than other parts, and if the function of the accumulator cannot be obtained, the shock absorber itself needs to be replaced. In particular, when the shock absorber is used in a pressure atmosphere, if external air enters the shock absorber, the accumulator is crushed by the air entering from the outside, and the stroke length of the rod is shortened.

  On the other hand, in shock absorbers used in an atmosphere where liquid scatters, the surrounding scattered liquid droplets may enter the inside of the shock absorber from between the rod and the sealing member in contact with the rod, and when the liquid enters, the accumulator expands. The volume of contraction of the liquid that has entered the shrinkage is reduced, and sufficient shock absorption characteristics cannot be obtained. In particular, in shock absorbers used under pressures above atmospheric pressure, if liquid adheres to the outer peripheral surface of the rod, the droplets may enter the inside of the shock absorber from the rod. In the case of a shock absorber, if the accumulator is damaged, the air leaked from it may leak out from the seal part such as the rod packing part and reduce the surrounding vacuum.

  An object of the present invention is to perform shock absorption without incorporating an accumulator inside.

  Another object of the present invention is to improve the durability of the shock absorber.

  The shock absorber according to the present invention includes a cylindrical case provided with cover portions having rod through holes at both ends, an operating end projecting from one end of the cylindrical case, and provided at the other end of the cylindrical case. A rod that is mounted between the cover portion at both ends and a rod that is mounted so as to be movable in the axial direction in the cylindrical case by projecting a retracting end portion from the cover portion that is formed, is disposed in the liquid storage chamber. And a piston that is provided on the rod and moves in the liquid as the rod moves, and a spring that is mounted in the cylindrical case and applies a spring force in a direction in which the operating end projects from the rod. And the piston moves in the liquid storage chamber having a constant volume when the rod is moved.

  The shock absorber according to the present invention is characterized in that the other end of the cylindrical case covers the retracted end of the rod.

  In the shock absorber of the present invention, an oil injection hole communicating with the liquid storage chamber is formed in the rod, and a closing member for closing the oil injection hole is provided at an end of the rod, and the liquid storage from the oil injection hole is provided. A liquid is injected into the chamber.

  The shock absorber according to the present invention is characterized in that one of the cover portions is formed integrally with the cylindrical case, and the other cover portion is attached to the cylindrical case.

  According to the present invention, both ends of the rod with which the moving member collides are protruded from the end of the cylindrical case and mounted in the cylindrical case, and the piston provided on the rod is stored in the liquid formed in the cylindrical case. Since the rod is disposed in the chamber, when the rod is moved in the axial direction, the volume of the liquid storage chamber is kept constant without any change regardless of the position of the piston in the axial direction.

  Therefore, the impact force applied to the rod is absorbed by the spring force of the spring member and the flow of the liquid in the liquid storage chamber, and the liquid in the liquid storage chamber is absorbed as the volume of the liquid storage chamber changes. It is not necessary to incorporate an accumulator for returning to the inside of the cylindrical case.

  Since no accumulator is required, the life of the shock absorber is not reduced due to deterioration of the accumulator, and the durability of the shock absorber can be improved. Further, since no accumulator is required, there is no outflow of air due to damage to the accumulator and no reduction in the external vacuum. Further, since no accumulator is used, even if liquid enters the inside from the outer peripheral surface of the rod when used under a pressure higher than atmospheric pressure, the function of the shock absorber is not impaired. In this way, the shock absorber can be used under either positive pressure or negative pressure other than atmospheric pressure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a shock absorber according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a reciprocating table driving device in which the shock absorber shown in FIG. 1 is incorporated.

  As shown in FIG. 1, the shock absorber 10 has a cylindrical case 11, and a male screw 11 a is formed on the outer peripheral surface of the cylindrical case 11. A nut 12 is screw-coupled to the male screw 11a. When the shock absorber 10 is fixed to the mounting member, the nut 12 is inserted in a state where the cylindrical case 11 is passed through a through hole formed in the mounting member. Will be tightened from both sides of the mounting member.

  When the left end portion of the cylindrical case 11 in FIG. 1 is the front end and the right end portion is the rear end portion, a cover portion 13 is integrally formed at the rear end portion of the cylindrical case 11. A hole 14 is provided. The cylindrical case 11 has inner peripheral surfaces 15a to 15d that gradually increase in inner diameter from the cover 13 toward the tip. A cylindrical cover portion 16 is attached to the inner peripheral surface 15d on the distal end portion side, and a rod through hole 17 is formed in the cover portion 16. A cylindrical spacer 18 is disposed outside the cover portion 16, and the cover portion 16 is fixed to the cylindrical case 11 via a spacer by a fixing plug 19 fixed to the tip of the cylindrical case 11.

  A rod 21 is mounted in the cylindrical case 11 so as to be movable in the axial direction. One end of the rod 21 passes through the rod through-hole 17 and protrudes to the outside from the distal end side of the cylindrical case 11, so that the working end. Part 22 is provided. The other end portion of the rod 21 passes through the rod through hole 14 of the cover portion 13, and a portion protruding outward from the cover portion 13 is a retreat end portion 23. In the case shown in FIG. 1, the receding end portion 23 projects outward from the rear end side of the cylindrical case 11. A rubber tip cap 24 is fixed to the operating end portion 22, and the moving member collides with the tip cap 24, but the tip end of the rod 21 is directly provided without providing the tip cap 24. You may make it make a moving member collide.

  Inside the cylindrical case 11, a liquid storage chamber 25 is formed between the cover portions 13 and 16 at both ends. In this liquid storage chamber 25, a liquid L for attenuating the impact applied to the rod 21 is shown in FIG. Silicon oil is enclosed as shown with dots. In order to prevent the liquid L from leaking from between the cover portion 13 and the rod 21, a sealing member 26 having a U-shaped cross section is provided inside the cover portion 13 and positioned between the inner peripheral surface 15 a and the rod 21. In order to prevent the liquid L from leaking from between the cover portion 16 and the rod 21, a seal member 27 having a U-shaped cross section is incorporated in an annular groove formed on the inner peripheral surface of the cover portion 16. In order to prevent leakage from between the cover portion 16 and the cylindrical case 11, a seal member 28 having a circular cross section is incorporated in an annular groove formed on the outer peripheral surface of the cover portion 16.

  In order to inject the liquid L into the liquid storage chamber 25, an oil injection hole 29 is formed in the rod 21, and the oil injection hole 29 communicates with the liquid storage chamber 25 through a communication hole 29a. Steel balls 30 for closing the opening are attached to both ends of the oil injection hole 29 as a closing member. When injecting liquid, only the steel ball 30 at one end of the rod 21 is attached. After injecting the liquid L from the opening at the other end under the condition, the opening at the other end is closed by the steel ball 30. A screw member may be fixed to the other end on the liquid injection side instead of the steel ball 30. In that case, the liquid leaks by fixing a sealing material such as an O-ring with the screw member. Will be prevented.

  The rod 21 is provided with a piston 31 positioned in the liquid storage chamber 25, and the liquid storage chamber 25 is divided into two storage chambers 25 a and 25 b by the piston 31, and between the piston 31 and the rod 21. The two storage chambers 25a and 25b are communicated with each other through a gap 32 formed in the inner space. A spring receiving ring 33 is fixed inside the cylindrical case 11, and a compression coil spring 34 is mounted between the spring receiving ring 33 and the rear end side of the cylindrical case so as to surround the rod 21. A spring force is applied to the rod 21 by the spring 34 in a direction in which the operating end 22 protrudes. The rod 21 is provided with a large-diameter stopper 35. One surface of the large-diameter stopper 35 abuts against the end surface of the cover portion 16 by a spring force, and the other surface abuts the piston 31. The large diameter stopper 35 restricts the amount of protrusion at which the operating end 22 of the rod 21 becomes the forward limit position, and the piston 31 is pushed in by the large diameter stopper 35 when the rod 21 moves backward.

  Both ends of the piston 31 are provided on a rod 21 projecting outward from both ends of the cylindrical case 11. The rod 21 has substantially the same outer diameter as a whole, and the piston 31 and the rod occupying the liquid storage chamber 25. 21, the large diameter stopper 35, the spring receiving ring 33, etc., the total volume is constant no matter where the rod 21 moves in the axial direction, and no matter what position the rod 21 moves in the axial direction, the liquid The volume of the storage chamber 25 is constant and unchanged.

  As shown in FIG. 1, when no external force is applied to the rod 21, the rod 21 is moved forward until the operating end 22 reaches the forward limit position by the spring force. When the moving member collides with the tip cap 24, the rod 21 moves backward so that the operating end 22 enters the cylindrical case 11, and the retracted end 23 further moves outward from the state shown in FIG. Protruding. During the backward movement, the piston 31 moves in the liquid storage chamber 25 having a constant volume while the piston 31 flows the liquid L through the gap 32 from the one storage chamber 25b toward the other storage chamber 25a. Therefore, the impact force applied to the rod 21 is absorbed by the impact absorbing action by the compression coil spring 34 and the damping action by the flow of the liquid L.

  Accordingly, even if the moving member collides with the rod 21, the moving member is gradually decelerated without causing a loud collision sound, and the moving member stops and the rod 21 moves in the liquid storage chamber 25 in the axial direction. Since the volume does not change, there is no need to absorb the liquid L with an accumulator as in the conventional case. In addition, since the accumulator is not incorporated, there is no volume change in the liquid storage chamber 25, there is no possibility of liquid droplets entering between the rod 21 and the rod through holes 14 and 17, and the pressure atmosphere is higher than atmospheric pressure. Even if it is used, the droplets are prevented from entering the inside from between the rod 21 and the rod through holes 14 and 17. In addition, since no accumulator is incorporated, no pressure is applied to the liquid L in the liquid storage chamber 25 by the accumulator, and the liquid L is difficult to leak from the inside even when used in a negative pressure atmosphere. The shock absorber having such a configuration is suitable as a small shock absorber in which the outer diameter of the rod 21 is about 3 to 6 mm and the movement stroke of the rod 21 is about 2 to 30 mm.

  The reciprocating table driving device 40 shown in FIG. 2 has a rectangular parallelepiped cylinder body 41, and the cylinder body 41 is provided with a reciprocating table 43 that can reciprocate in the longitudinal direction along a guide rail 42. ing. A piston slidably incorporated in a cylinder hole formed in the cylinder body 41 is connected to a reciprocating table 43, and the reciprocating table 43 is driven by compressed air. Attachment plates 44 and 45 are fixed to both ends of the cylinder body 41, and the shock absorber 10 shown in FIG. 1 is attached to each of the attachment plates 44 and 45. Therefore, when the reciprocating table 43 moves to the left in FIG. 2, the impact of the reciprocating table 43 is absorbed by the shock absorber 10 attached to the mounting plate 44, and the reciprocating table 43 is positioned and stopped at a predetermined position. 2, the shock absorber 10 attached to the mounting plate 45 absorbs the impact of the reciprocating table 43, and the reciprocating table 43 is positioned and stopped at a predetermined position.

  FIG. 3 is a cross-sectional view showing a shock absorber according to another embodiment of the present invention, and members common to the members constituting the shock absorber shown in FIG. 1 are denoted by the same reference numerals. In the shock absorber 10 shown in FIG. 3, the cylindrical case 11 is longer than that shown in FIG. 1 so that the retracted end portion 23 of the rod 21 does not protrude from the rear end side of the cylindrical end portion. A closing cap 46 is attached to the rear end of the cylindrical case 11. As described above, when the retracting end portion 23 of the rod 21 is covered with the cylindrical case 11, it is possible to prevent the impacting object from directly hitting the retracting end portion 23, and the closure cap 46 is attached to the inside of the cylindrical case 11. It is possible to prevent dust from entering.

  As shown in FIG. 3, a screw 47 is secured to the opening of the oil injection hole 29 on the retracted end portion 23 side, so that the liquid L can be prevented from leaking from the oil injection hole 29. In addition, as described above, the seal material 48 is attached to the opening by the screw 47. The opening of the oil injection hole 29, that is, the opening on the working end 22 side is closed by a steel ball 30 as in the case shown in FIG. 48 may be closed. Such a sealing method can be applied to the shock absorber 10 shown in FIG.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, one cover portion 13 is integrally provided in the cylindrical case 11, but the two cover portions 13, 16 are separate parts from the cylindrical case 11 in the same manner as the other cover portion 16. 11 may be attached. FIG. 2 is a view showing an example of a device to which the shock absorber 10 is attached. The shock absorber 10 of the present invention is applied in any case as long as the movement is stopped by absorbing the impact force of the moving member. be able to. In the illustrated case, the cylindrical case 11 has a cylindrical shape for attaching the nut 12, but when the cylindrical case 11 is attached to the attached member without using the nut 12, a liquid storage chamber is provided inside. As long as 25 is formed, the outer peripheral surface shape of the cylindrical case 11 is not limited to a circular cross section, and may be a rectangle or a polygon.

It is sectional drawing which shows the shock absorber which is one embodiment of this invention. It is a perspective view which shows the reciprocating table drive device with which the shock absorber shown by FIG. 1 was integrated. It is sectional drawing which shows the shock absorber which is other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Shock absorber 11 Cylindrical case 12 Nut 13 Cover part 14 Rod through-holes 15a-15d Inner peripheral surface 16 Cover part 17 Rod through-hole 18 Spacer 19 Fixed plug 21 Rod 22 Operating end part 23 Retreat end part 24 End cap 25 Liquid accommodation Chambers 26 to 28 Seal member 29 Oil injection hole 30 Steel ball 31 Piston 32 Gap 33 Spring receiving ring 34 Compression coil spring 35 Large diameter stopper 46 Closure cap 47 Screw 48 Seal material

Claims (4)

A cylindrical case provided at both ends with cover portions each having a rod through hole;
An operating end is projected from one end of the cylindrical case, and a retracted end is projected from the cover provided at the other end of the cylindrical case, and is mounted in the cylindrical case so as to be movable in the axial direction. A rod to be
A piston formed between the cover portions at both ends and disposed in a liquid storage chamber for storing a liquid, provided in the rod, and moving in the liquid as the rod moves;
A spring member that is mounted in the cylindrical case and applies a spring force in a direction in which the operating end projects from the rod;
A shock absorber, wherein the piston moves in the liquid storage chamber having a constant volume when the rod is moved.   2. The shock absorber according to claim 1, wherein the other end of the cylindrical case covers a retracted end portion of the rod.   The shock absorber according to claim 1 or 2, wherein an oil injection hole communicating with the liquid storage chamber is formed in the rod, and a closing member for closing the oil injection hole is provided at an end of the rod, A shock absorber, wherein a liquid is injected into the liquid storage chamber.   The shock absorber according to any one of claims 1 to 3, wherein one of the cover portions is integrally formed with the cylindrical case, and the other cover portion is attached to the cylindrical case. shock absorber.

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