JP2009270585A - Shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock absorber to be used under environment where liquid droplets exist while holding desired shock absorbing effects over a long period. <P>SOLUTION: A sleeve 20 is mounted in a case body 11 of the shock absorber 10 reciprocatively in the axial direction, and the sleeve 20 is partitioned into a liquid storage chamber 21 on the side of the base end and a communication chamber 22. Spring force is applied to the sleeve 20 in the backward moving direction by a preload spring 29. In the case body 11, a rod 25 with its front end protruded is mounted reciprocatively in the axial direction. At the base end of the rod 25, a piston is provided which is moved in liquid L filled in the liquid storage chamber 21. When the sleeve 20 is excessively moved forward with the liquid flowing into the liquid storage chamber 21, a sleeve seal 39 cancels its sealing of a space between the outer peripheral face of the sleeve 20 and the inner peripheral face of the case body 11 to discharge the liquid from the liquid storage chamber 21 into the communication chamber 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a shock absorber that relieves an impact force applied to a moving member when stopping the movement of the moving member, and more particularly to a shock absorber that can be used in an atmosphere in which droplets are scattered.

A shock absorber, ie, a shock absorber, is used to relieve the impact force applied to the moving member when the reciprocating moving member stops at the position of the reciprocating end. As a shock absorber used for such applications, a rod is projected from one end of a cylindrical case so that the moving member collides with the rod, and the impact of the moving member is applied while the rod moves backward into the cylindrical case. There is a type of absorption (see Patent Document 1). This type of shock absorber incorporates a coil spring that applies a spring force in the protruding direction to the rod in a cylindrical case, and a shock-absorbing liquid made of silicone oil or the like is enclosed, and the piston fixed to the rod Is moved in the liquid by the backward movement of the rod.
Japanese Utility Model Publication No. 61-55530

  In such a shock absorber, a sealing material is incorporated in order to prevent liquid from flowing into the shock absorber from the outer peripheral surface of the rod. However, the shock absorber has an environment or atmosphere in which droplets exist. When used in the above, external droplets may flow into the interior from between the sealing material and the rod. In particular, when the shock absorber is attached to a device or facility that uses a liquid such as cutting oil, such as a cutting device, the shock absorber is exposed to the droplet atmosphere, so there is a possibility that the liquid may be mixed inside. Get higher.

  When the V packing is used as the sealing material, the V packing has directionality to the seal. If the V packing is directed to the outside, the effect of preventing the inflow of liquid from the outside is enhanced. The liquid adhering to the rod may pass through the V packing and flow into the shock absorber. If the liquid flows excessively into the shock absorbing liquid in the shock absorber from the outside, the desired shock absorbing effect will not be obtained and the shock absorber will be damaged, reducing the durability of the shock absorber. It will be.

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

  Another object of the present invention is to enable a desired shock absorbing effect to be maintained over a long period of time even when a shock absorber is used in an environment where droplets are present.

  The shock absorber according to the present invention includes a case body whose base end portion is closed and a rod cover is provided at the front end portion, and a base end portion side which is reciprocally mounted in the axial direction in the case body and filled with liquid. A sleeve that divides a liquid storage chamber and a communicating chamber on a distal end side that communicates with the outside in the case body; and the sleeve that penetrates the sleeve and the rod cover and is removably mounted in the case body in an axial direction; A rod sealed between the sleeve and a rod seal provided between the rod and a spring provided in a proximal end portion of the rod and moving in the liquid storage chamber in the axial direction and in the protruding direction of the rod Is incorporated in the communication chamber with a piston that is applied by an impact absorbing spring, and moves to the tip side by the liquid in the liquid storage chamber when the rod moves backward by an external force A preload spring that applies a spring force in a backward direction to the sleeve, and an outer peripheral surface of the sleeve and the case when the sleeve is excessively moved forward by the liquid flowing into the liquid storage chamber via the rod seal. And a sleeve seal that releases the seal with the inner peripheral surface of the body and discharges the liquid in the liquid storage chamber to the communication chamber.

  The shock absorber according to the present invention is characterized in that the case body is provided with an abutting step portion that contacts the end surface of the sleeve and regulates the position of the sleeve in the backward direction. The shock absorber according to the present invention is characterized in that a large-diameter hole is formed in the case body that forms a liquid passage gap between the sleeve and the sleeve seal when the sleeve moves forward more than a predetermined stroke. To do. The shock absorber according to the present invention is characterized in that a guide groove is formed in the case body to form a liquid passage gap between the sleeve and the sleeve seal when the sleeve moves forward more than a predetermined stroke. To do.

  In the shock absorber according to the present invention, a spiral groove for communicating the communication chamber with the outside is formed in the rod cover. The shock absorber according to the present invention is characterized in that a communication hole for communicating the communication chamber with the outside is formed in the case body.

  According to the present invention, when excessive liquid is mixed into the liquid storage chamber from the outside, when the rod moves backward, the sleeve moves forward by a predetermined stroke or more in synchronization with the backward movement, and the liquid storage chamber Drain the liquid. As a result, the shock absorber is used in an environment where droplets are present, and even if liquid is mixed inside, the excessively mixed liquid is discharged to the outside, so that the desired shock absorbing effect is maintained for a long period of time. The durability of the shock absorber can be improved.

  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 non-operating state of a shock absorber according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the shock absorber in an operating state, and FIG. It is an expanded sectional view which shows a part of shock absorber in the operation state at the time of doing.

  The shock absorber 10 has a cylindrical case body 11. The case body 11 is closed at the base end by a bottom wall portion 12 integrated with the case body 11, and a housing hole 13 with a bottom is formed inside. The housing hole 13 is opened at the distal end portion of the case body 11, and the rod cover 14 is attached to the distal end portion of the opened case body 11. A male screw 15 is formed on the outer peripheral surface of the case body 11, and locking nuts 16 and 17 are screwed to the male screw 15. The shock absorber 10 is fastened to a mounting member (not shown) by the locking nuts 16 and 17. Is done. However, as a mounting method of the shock absorber 10, a bracket may be attached to the case body 11 without using the lock nuts 16 and 17. Further, the cover member may be attached to the base end portion without providing the bottom wall portion 12 integrally with the base end portion of the case body 11.

  A sleeve 20 is mounted inside the case body 11 so as to be capable of reciprocating in the axial direction. The sleeve 20 allows the accommodation hole 13 in the case body 11 to communicate with the liquid accommodation chamber 21 on the base end side. It is divided into a communication chamber 22. The liquid storage chamber 21 separated from the communication chamber 22 by the sleeve 20 is filled with silicone oil or the like as the shock absorbing liquid L, and the bottom of the case body 11 is filled with the liquid L in the liquid storage chamber 21. An injection hole 23 is formed in the wall 12, and the injection hole 23 is sealed by a sealing screw 24 after liquid injection.

  A rod 25 is attached to the case body 11 so as to be reciprocally movable in the axial direction, and the tip of the rod 25 penetrates the through hole 18 of the rod cover 14 and protrudes to the outside. The rod 25 passes through a through hole 26 formed at the center of the sleeve 20, and a large diameter hole 26 a formed on the base end side of the sleeve 20 seals between the rod 25 and the sleeve 20. A seal 27 is attached. The rod seal 27 is formed of an elastic material such as rubber, and the inner annular portion 27a and the outer annular portion 27b are integrated at one end in the axial direction and separated toward the other end to become an open end. It is a V-packing, and the open ends of the inner annular portion 27 a and the outer annular portion 27 b are attached to the sleeve 20 so as to face the liquid storage chamber 21. An annular groove may be formed in the rod 25, and a rod seal 27 may be attached to the annular groove.

  An abutting ring 28 is attached to an end portion of the large-diameter hole 26 a of the sleeve 20, and the abutting ring 28 comes into contact with an abutting step portion 19 formed on the inner surface of the case body 11. . A preload spring 29 made of a compression coil spring having one end abutting on the rod cover 14 and the other end abutting on the sleeve 20 is mounted in the communication chamber 22. The preload spring 29 applies a spring force in the backward direction to the sleeve 20, and the abutting ring 28 abuts against the abutting step portion 19, so that the backward limit position of the sleeve 20 is regulated. Yes.

  A small diameter fitting portion 31 is formed at the proximal end portion of the rod 25, and a flange portion 32 and a spring receiving collar 33 are attached to the fitting portion 31. The flange portion 32 is provided with a tapered portion 34 having a diameter that decreases toward the spring receiving collar 33, and an annular piston 35 is provided outside the tapered portion 34. The piston 35 is disposed in the liquid storage chamber 21 and moves in the axial direction in the liquid storage chamber 21 together with the rod 25. An impact absorbing spring 36 made of a compression coil spring is mounted between the spring receiving collar 33 and the bottom wall portion 12, and the tip of the rod 25 is placed on the case body of the rod 25 and the piston 35 by the impact absorbing spring 36. A spring force in a direction protruding from the tip of 11 is applied. In the illustrated case, the flange portion 32, the taper portion 34 integrated with the flange portion 32, and the base end portion of the rod 25 are attached, but the flange portion 32 and the taper portion 34 are integrated with the rod 25. You may make it form.

  As shown in FIG. 1, under the state where no external force is applied to the rod 25 of the shock absorber 10, the sleeve 20 is in the retreat limit position where the abutting ring 28 contacts the step portion 19. The piston 35 is set to the forward limit position where the flange portion 32 is abutted against the abutment ring 28 of the sleeve 20 by the spring force of the shock absorbing spring 36. At this time, the spring force in the direction of advancing the sleeve 20 is applied to the sleeve 20 by the spring force of the shock absorbing spring 36. However, the preload spring 29 has a larger spring force, that is, a resilient force than the shock absorbing spring 36. Therefore, the sleeve 20 holds the retreat limit position where the butting ring 28 contacts the step portion 19.

  The liquid storage chamber 21 is partitioned between the piston 35 and the bottom wall portion 12, and is divided into an impact absorbing portion 21 a in which an impact absorbing spring 36 is incorporated, and a retracting portion 21 b between the piston 35 and the sleeve 20. When an external force is applied to the rod 25 in a direction in which the rod 25 is moved backward, the piston 35 moves in the liquid L in the liquid storage chamber 21 as the rod 25 moves backward. 14 is moved within the range of the stroke S to the retreat limit position coinciding with the end face of 14. At this time, a part of the liquid L in the liquid storage chamber 21 passes from the shock absorbing portion 21a side to the retracting portion 21b side through a gap 37 formed between the inner peripheral surface of the case body 11 and the outer peripheral surface of the piston 35. Therefore, the volume of the shock absorbing portion 21a contracts and the volume of the retracting portion 21b expands. As described above, the piston 35 moves in the liquid L of the liquid storage chamber 21 to cause the liquid L to generate a flow from the impact absorbing portion 21a to the retracting portion 21b through the gap 37, thereby absorbing the shock applied to the rod 25. Is done. A constricted portion 38 is formed adjacent to the flange portion 32 at the proximal end portion of the rod 25 so that the liquid L smoothly flows from the shock absorbing portion 21a into the retracting portion 21b.

  The portion of the accommodation hole 13 corresponding to the range of the stroke S in which the piston 35 moves from the forward limit position shown in FIG. 1 to the reverse limit position shown in FIG. 2 has an inner diameter that gradually decreases toward the base end. The gap 37 is narrowed as the piston 35 moves to the retreat limit position. Thereby, the resistance due to the viscosity of the liquid gradually increases as the rod 25 moves from the forward limit position to the backward limit position.

  When the rod 25 moves to the retreat limit position by the stroke S, the volume corresponding to the stroke S of the rod 25 enters the liquid storage chamber 21, so that the volume of the liquid storage chamber 21 increases by the volume. Become. The sleeve 20 slides toward the tip as shown in FIG. 2 by a stroke T corresponding to the increased volume. During this sliding, the liquid L in the liquid storage chamber 21 enters between the inner ring portion 27a and the outer ring portion 27b of the rod seal 27 made of V packing from between the butting ring 28 and the constricted portion 38, Since pressure is applied to the rod seal 27 in the direction in which they are expanded, liquid leakage from the rod 25 and the rod seal 27 is prevented.

  In order to seal between the outer peripheral surface of the sleeve 20 and the inner peripheral surface of the accommodation hole 13 of the case body 11, a sleeve seal 39 made of an O-ring is mounted in an annular groove formed on the outer peripheral surface of the sleeve 20. . As a result, the rod 25 moves from the forward limit position shown in FIG. 1 to the backward limit position as shown in FIG. 2 by an impact force in a state where an appropriate amount of liquid L is filled in the liquid storage chamber 21. In some cases, the sleeve 20 reciprocates within a set range of an appropriate stroke T. In this range of the stroke T, the sleeve seal 39 contacts the inner peripheral surface of the storage hole 13 and the liquid in the liquid storage chamber 21. Is prevented from leaking outside.

  The communication chamber 22 communicates with the outside through a communication hole 41 formed in the case body 11. The rod cover 14 includes an inner cylinder 14 a in which a through hole 18 is formed, and an outer cylinder 14 b that is fitted between the inner cylinder 14 a and the case body 11. A flange portion 42 that abuts against the inner end surface of the outer cylinder body 14b is provided at the inner end portion of the inner cylinder body 14a, and the outer end portion of the outer cylinder body 14b abuts against the tip surface of the case body 11. A flange portion 43 is provided, and the rod 25 moves backward to a position where the end surface of the flange portion 43 and the tip surface of the rod 25 coincide with each other.

  A spiral groove 44 is formed in the through hole 18 of the inner cylindrical body 14 a so as to connect the communication chamber 22 and the outside. The communication chamber 22 is formed by a plurality of communication holes 41 and a spiral groove 44. It is communicated to. Thus, since the communication chamber 22 communicates with the outside, when the sleeve 20 moves forward from the retreat limit position shown in FIG. 1, the air in the communication chamber 22 is discharged to the outside and moves in the reverse direction. In some cases, outside air flows into the communication chamber 22 from the outside. Instead of the spiral groove 44, a plurality of linear grooves may be formed in the through hole 18 of the inner cylindrical body 14a, and the communication chamber is formed only by the communication hole 41 without forming these grooves. 22 may be communicated to the outside, or may be communicated only by the groove without forming the communication hole 41.

  As described above, the rod 25 moves from the forward limit position to the reverse limit position by an external force applied to the rod 25 by a moving member (not shown) under a state where the liquid storage chamber 21 is filled with an appropriate amount of the liquid L. In some cases, the sleeve 20 reciprocates within a set stroke T range, and in this stroke T range, the sleeve seal 39 contacts the inner peripheral surface of the receiving hole 13 and the inner periphery of the sleeve 20 and the case body 11. The space between the surfaces is sealed. If the shock absorber 10 is used in an environment where droplets exist, the droplets may be mixed into the communication chamber 22 from the outside. When the shock absorber 10 is used in a horizontal state, if the communication hole 41 is on the lower side, the liquid droplets mixed in the communication chamber 22 are discharged from the communication hole 41 to the outside. On the other hand, when the shock absorber 10 is used in a vertical state with the rod 25 facing upward, there is a possibility that liquid droplets may be mixed into the communication chamber 22 from the outside through between the rod 25 and the rod cover 14. However, by forming the spiral groove 44 in the rod cover 14, the sliding resistance of the rod 25 applied from the rod cover 14 is reduced, and a clearance for smoothly reciprocating the rod 25 is secured, while the outside is secured. The mixing of droplets from can be reduced.

  When the shock absorber 10 is used with the rod 25 facing upward, there is a high possibility that liquid droplets are mixed into the communication chamber 22 from the communication hole 41 or the spiral groove 44. When liquid droplets are mixed into the communication chamber 22, the liquid droplets adhere to the outer peripheral surface of the rod 25 in the form of a film, and when the rod 25 moves backward by the moving member, it enters the liquid storage chamber 21 via the rod seal 27. There is a possibility of mixing. When the amount of mixed droplets increases, the stroke of the forward movement of the sleeve 20 when the rod 25 moves to the retreat limit position becomes larger than the proper stroke T described above.

  FIG. 3 shows a state in which the sleeve 20 is moved forward in a state where excessive liquid is mixed in or flows into the liquid storage chamber 21 from the outside. At this time, the sleeve 20 moves forward with a stroke increased by the discharge stroke Ta from the above-described proper stroke T. When the sleeve 20 is moved forward by increasing the discharge stroke Ta, the sleeve seal 39 reaches the large-diameter hole 13b formed in the accommodation hole 13 of the case body 11. The large diameter hole portion 13b is set to be larger than the outer diameter of the sleeve seal 39, and a liquid passage gap 45 is formed between the large diameter hole portion 13b and the sleeve seal 39. The liquid is returned to the communication chamber 22 through the liquid passage gap 45. The liquid returned to the communication chamber 22 is discharged from the communication hole 41 to the outside.

  Therefore, the shock absorber 10 is attached to a device or facility in which a liquid such as cutting oil is used, such as a cutting device, and is used in an environment or atmosphere in which liquid droplets are present. Even if an external liquid is mixed in 21, if the liquid is mixed excessively, the liquid in the liquid storage chamber 21 is discharged to the outside due to an increase in the movement stroke of the sleeve 20. Thereby, the shock absorber 10 can maintain a desired impact absorption effect for a long period of time, and can improve the durability of the shock absorber.

  In addition, when the liquid L in the liquid storage chamber 21 has an appropriate amount of oil in the storage hole 13, a tapered surface 46 is formed between a portion where the sleeve seal 39 is in sliding contact with the large-diameter hole portion 13 b. When the amount of the discharge stroke Ta increases in the forward direction of the sleeve 20, the liquid passage gap 45 increases.

  The shock absorber 10 described above is attached to a member that reciprocates in the axial direction or a stationary member in a horizontal state or a vertical state as illustrated, and a moving member that moves relative to the shock absorber 10 collides with the rod 25. In doing so, the impact of the moving member is absorbed. When the moving member collides with the rod 25, the rod 25 moves backward. At this time, the piston 35 moves in the liquid L in the liquid storage chamber 21, and the impact force of the moving member is absorbed by the liquid L. The When the rod 25 moves to the retreat limit position shown in FIG. 2, the moving member is abutted against the end surface of the rod cover 14 that forms the front end surface of the shock absorber 10, and the position of the movement limit of the moving member relative to the shock absorber 10 is restricted. The

  In the process in which the rod 25 moves from the forward limit position shown in FIG. 1 to the backward limit position shown in FIG. 2, the piston 35 moves through the tapered hole 13 a of the accommodation hole 13, so that the gap increases as the rod 25 reaches the backward limit position. 37 gradually decreases, and the resistance of the rod 25 and the piston 35 due to the viscosity of the liquid L moving in the liquid storage chamber 21 gradually increases. In this moving process, the impact is also absorbed by the spring force of the impact absorbing spring 36. When the moving member moves away from the rod 25, the rod 25 moves to a forward limit position where the flange portion 32 abuts against the abutting ring 28 of the sleeve 20 by the spring force of the shock absorbing spring 36. When the liquid in the liquid storage chamber 21 has an appropriate amount of oil, the sleeve 20 moves within the range of the appropriate stroke T when the rod 25 moves from the forward limit position to the reverse limit position. Keeps the state of sealing contact with the inner surface of the accommodation hole 13 in the case body 11, and the liquid in the liquid accommodation chamber 21 is prevented from leaking to the outside.

  When the shock absorber 10 is used in an environment where droplets are present, the droplets enter the communication chamber 22 and pass through the rod seal 27 from between the through hole 26 of the sleeve 20 and the rod 25. There is a risk of mixing into the liquid storage chamber 21. If liquid is mixed in the liquid storage chamber 21, the amount of liquid in the liquid storage chamber 21 will increase. However, if excessive liquid is mixed in the liquid storage chamber 21, the sleeve 20 when the rod 25 is operated is activated. The forward movement stroke becomes larger than the normal movement stroke T, and the sleeve 20 moves by being increased by the discharge stroke Ta. Thereby, since the liquid in the liquid storage chamber 21 is discharged to the outside, the amount of liquid in the liquid storage chamber 21 is always maintained in an appropriate state, and the shock absorber 10 maintains a predetermined shock absorption characteristic for a long period of time. Can do.

  FIG. 4 is an enlarged cross-sectional view showing a part of a shock absorber according to another embodiment of the present invention. In the shock absorber 10 described above, when the sleeve 20 is excessively advanced to the discharge stroke Ta by forming the large-diameter hole 13b in the portion corresponding to the communication chamber 22 in the accommodation hole 13, the liquid passage gap In the shock absorber 10 shown in FIG. 4, one or more guide grooves 45 a extending in the axial direction are formed in a portion corresponding to the communication hole 22 in the accommodation hole 13. A liquid passage gap 45 is formed.

  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.

It is sectional drawing which shows the non-operation state of the shock absorber which is one embodiment of this invention. It is sectional drawing which shows the shock absorber in an operation state. It is an expanded sectional view showing a part of shock absorber in the operation state when excessive liquid flows in from the outside. It is an expanded sectional view showing a part of shock absorber which is other embodiments of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Shock absorber 11 Case body 13 Accommodating hole 14 Rod cover 18 Through hole 19 Butting step part 20 Sleeve 21 Liquid accommodating chamber 21a Shock absorbing part 21b Retreating part 22 Communication room 25 Rod 26 Through hole 27 Rod seal 29 Preload spring 35 Piston 36 Shock absorbing spring 37 Clearance 39 Sleeve seal 41 Communication hole 44 Spiral groove 45 Liquid passage gap 45a Guide groove

Claims (6)

A case body in which a base end portion is closed and a rod cover is provided at a distal end portion;
A sleeve which is mounted in the case body so as to be reciprocally movable in the axial direction, and divides a liquid storage chamber on the base end side filled with a liquid and a communication chamber on the distal end side communicating with the outside in the case body;
A rod that passes through the sleeve and the rod cover and is reciprocally attached to the case body in the axial direction, and is sealed between the sleeve by a rod seal provided between the sleeve,
A piston which is provided at a base end portion of the rod and moves in the liquid storage chamber in the axial direction and a spring force in the protruding direction of the rod is applied by an impact absorbing spring;
A preload spring that is incorporated in the communication chamber and applies a spring force in the backward direction to the sleeve that moves to the tip side by the liquid in the liquid storage chamber when the rod moves backward by an external force;
When the sleeve excessively moves forward due to the liquid flowing into the liquid storage chamber through the rod seal, the seal between the outer peripheral surface of the sleeve and the inner peripheral surface of the case body is released to release the seal in the liquid storage chamber. A shock absorber having a sleeve seal for discharging liquid into the communication chamber.   2. The shock absorber according to claim 1, wherein the case body is provided with an abutting step portion that contacts the end surface of the sleeve and regulates the position of the sleeve in the backward direction.   3. The shock absorber according to claim 1, wherein a large-diameter hole that forms a liquid passage gap with the sleeve seal when the sleeve is excessively moved forward by a predetermined stroke or more is formed in the case body. Shock absorber characterized by that.   3. The shock absorber according to claim 1 or 2, wherein a guide groove is formed in the case body that forms a liquid passage gap between the sleeve and the sleeve seal when the sleeve moves forward more than a predetermined stroke. A characteristic shock absorber.   The shock absorber according to any one of claims 1 to 4, wherein the rod cover is formed with a spiral groove that allows the communication chamber to communicate with the outside.   The shock absorber according to any one of claims 1 to 5, wherein a communication hole for communicating the communication chamber with the outside is formed in the case body.

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