JP4999714B2 - shock absorber - Google Patents

Description

  The present invention relates to a shock absorber.

  As a conventional shock absorber, there is one in which a piston is arranged through a piston rod in a cylinder filled with a working fluid, and the inside of the cylinder is divided into a pressure chamber side and a non-pressure chamber side.

  In such a shock absorber, a flow path that connects the pressure chamber side and the non-pressure chamber side is formed in the piston, and the working fluid is caused to flow between the pressure chamber side and the non-pressure chamber side in accordance with the movement of the piston to be attenuated. Generate power.

  However, in the conventional structure, a predetermined stroke length for moving the piston is necessary to secure the buffering performance, the cylinder is lengthened, and the piston rod is lengthened accordingly. As a result, the shock absorber is increased in size as a whole, and the installation location is limited.

JP 2005-188601

  The problem to be solved is that if the buffering performance is secured, the installation location is limited.

In the present invention, in order to improve the degree of freedom of the installation location while ensuring the buffer performance, a first fluid chamber and a second fluid chamber having an accumulator are partitioned in a cylinder filled with a working fluid, and the first A flow path is provided between the first fluid chamber and the second fluid chamber so as to communicate both the fluid chambers. A piston is supported in the first fluid chamber so that the piston can move in and out . A shock absorber capable of pressurizing a working fluid in a fluid chamber and flowing toward the second fluid chamber, wherein the piston has a small diameter on an inner peripheral surface of a large-diameter piston body opened straight to the first fluid chamber. The piston body is formed of a multi-stage piston body with different large and small diameters provided in a slidable manner, and the large diameter piston body is arranged to be movable with respect to the first fluid chamber and the opening of the cylinder From its tip Is capable of projecting and moving in accordance with the retreating movement with respect to the first fluid chamber, and the small-diameter piston body moves within the range of moving with respect to the first fluid chamber while sliding on the inner peripheral surface of the large-diameter piston body. The tip wall of the small-diameter piston body can project and move from an opening formed in the tip wall of the large-diameter piston body, and the small-diameter piston body is attached in the projecting direction between the small-diameter piston body and the cylinder side. A return spring is provided to urge the small-diameter piston body and the large-diameter piston body into a standby state protruding from the respective openings, and the distal end wall of the small-diameter piston body receives an external force to receive the distal end of the large-diameter piston body. When moving into the opening of the wall, the piston surface of the small diameter piston body produces an effect on the first fluid chamber, and the small diameter piston body moves into the opening of the tip wall of the large diameter piston body. Then, the tip wall of the large-diameter piston body takes over the external force so that the small-diameter piston body and the large-diameter piston body move together, and the piston surface of the large-diameter piston body is added to the piston surface of the small-diameter piston body. It is characterized by generating a drag against the chamber .

  The shock absorber according to the present invention is composed of a multi-stage piston body in which the piston operates integrally in the course of the immersive movement, so that the overall stroke length can be shortened and the overall size can be reduced. It is possible to improve the degree of freedom of installation location.

  Moreover, since the shock absorber can increase the piston area by operating the multistage piston body as one body, the drag when an external force is applied is reduced, and the drag is almost constant throughout the stroke. Buffering efficiency can be improved.

  Therefore, the shock absorber can be reduced in size while improving the buffer efficiency and ensuring the buffer performance.

  The purpose of improving the flexibility of the installation location while securing the buffer performance was realized by forming the piston with a nested multi-stage piston body.

1 is a cross-sectional view illustrating a shock absorber according to a first embodiment of the present invention.
[Composition of shock absorber]
As shown in FIG. 1, the shock absorber 1 according to the present embodiment includes a cylinder 3 and a piston 5 supported by the cylinder 3.

  The cylinder 3 is a so-called double cylinder type and includes an inner cylinder 7 and an outer cylinder 9. A fluid chamber 11 in which a working fluid having viscosity such as silicon oil is enclosed is formed in the inner cylinder 7. The fluid chamber 11 is partitioned into a first fluid chamber 15 on one side of the cylinder 3 and a second fluid chamber 17 on the other side by a partition wall 13 provided in the axially intermediate portion of the inner cylinder 7.

  An orifice 19 as a flow path is formed through the partition wall 13 at the center. The orifice 19 communicates between the first and second fluid chambers 15 and 17 and allows the working fluid to flow between the first and second fluid chambers 15 and 17. Therefore, the shock absorber 1 is a single hole type in which the first and second fluid chambers 15 and 17 communicate with each other through a single orifice 19.

  In the partition wall 13, a circulation hole 21 that communicates between the first and second fluid chambers 15 and 17 is formed through the outer peripheral side of the orifice 19. The recirculation hole 21 enables recirculation of the working fluid from the second fluid chamber 17 side to the first fluid chamber 15 side by a check valve 23 as a valve mechanism.

  In the check valve 23, a ring-shaped valve body 29 is held in a circumferential groove 27 formed in the inner periphery of the first fluid chamber 15 of the cylinder 3 so as to be movable in the axial direction of the cylinder 3. The check valve 23 opens and closes the circulation hole 21 by the valve body 29 moving in the axial direction by the pressure of the flowing working fluid. That is, in the check valve 23, when the working fluid flows from the first fluid chamber 15 side to the second fluid chamber 17 side, the valve element 29 moves to the partition wall 13 side to close the circulation hole 21, and the second fluid When the working fluid flows from the chamber 17 side to the first fluid chamber 15 side, the valve element 29 moves to the counter partition wall 13 side to open the circulation hole 21.

  A reservoir chamber 31 is formed between the inner and outer cylinders 7 and 9. The reservoir chamber 31 communicates with the second fluid chamber 17 via a communication passage 33 formed in the inner cylinder 7. An accumulator 35 is accommodated in the reservoir chamber 31. Accordingly, the accumulator 35 is provided on the outer periphery of the first and second fluid chambers 15 and 17.

  The accumulator 35 is made of, for example, an elastic body containing closed cells, and contracts by pressurization to reduce the volume. Therefore, the volume of the second fluid chamber 17 increases due to the contraction of the accumulator 35 and allows the working fluid to flow in.

  The piston 5 is supported on one side of the cylinder 3 so as to be movable in and out with respect to the first fluid chamber 15. The piston 5 includes multi-stage piston bodies 37 and 39 having different cylindrical large and small diameters. The multistage piston bodies 37 and 39 are provided in a nested manner.

  The large-diameter piston body 37 is inserted into the first fluid chamber 15 of the cylinder 3, and the inner peripheral side communicates with the first fluid chamber 15 of the cylinder 3. The large-diameter piston body 37 can move in and out of the first fluid chamber 15 through an opening 41 formed on one side of the cylinder 3.

  On the base end side of the outer peripheral surface 43 of the large-diameter piston body 37, a circular step 45 is formed. The step portion 45 slides on the inner peripheral surface 25 of the first fluid chamber 15 to guide the movement of the large-diameter piston body 37. Note that the large-diameter piston body 37 is guided to move in and out by sliding the outer peripheral surface 43 to the inner periphery of the opening 41 of the cylinder 3. The step portion 45 is engaged with the opening edge portion 47 of the cylinder 3 to prevent the large-diameter piston body 37 from coming off. A circumferential holding groove 49 is formed on the outer periphery of the step portion 45 to hold the seal member 51. The end surface of the step 45 is formed flush with the end surface of the large-diameter piston body 37, and constitutes a piston surface 53 for pressurizing the working fluid together with the end surface of the large-diameter piston body 37.

  The small diameter piston body 39 has substantially the same configuration as the large diameter piston body 37. The small diameter piston body 39 is inserted on the inner peripheral side of the large diameter piston body 37. The inner peripheral side of the small diameter piston body 39 communicates with the first fluid chamber 15 of the cylinder 3. The small-diameter piston body 39 can move in and out with respect to the inner peripheral side of the large-diameter piston body 37 through an opening 57 formed in the tip wall 55 of the large-diameter piston body 37.

  A circumferential step portion 61 is formed on the proximal end side of the outer peripheral surface 59 of the small diameter piston body 39. The step portion 61 slides on the inner peripheral surface 63 of the large-diameter piston body 37 to guide the movement of the small-diameter piston body 39 and engages with the opening edge (tip wall) 55 of the large-diameter piston body 37. Thus, the small diameter piston body 39 is prevented from coming off. Note that the small-diameter piston body 39 is guided to move in and out by sliding the outer peripheral surface 59 to the inner periphery of the opening 57 of the large-diameter piston body 37. A circumferential holding groove 65 is formed on the outer periphery of the step portion 61 to hold the seal member 67. The end surface of the step portion 61 is formed flush with the end surface of the small diameter piston body 39 to pressurize the working fluid. A piston surface 69 is formed.

The distal end wall 71 of the small diameter piston body 39 is substantially flush with the distal end wall 55 of the large diameter piston body 37 in the state of being immersed in the large diameter piston body 37. The inner surface of the tip wall 71 is a piston surface 73 that pressurizes the working fluid together with the piston surface 69. A return spring 75 is provided between the tip wall 71 and the partition wall 13 of the cylinder 3 to urge the small-diameter piston body 39 in the protruding direction. Thus, the standby state in which the piston 5 protrudes from the first fluid chamber 15 is maintained.
[Shock absorber operation]
FIG. 2 is a cross-sectional view showing the operation of the shock absorber of FIG.

  As shown in FIG. 2, the shock absorber 1 of this embodiment performs a stroke while the piston 5 contracts, and finally the contracted piston 5 strokes into the first fluid chamber 15 of the cylinder 3.

  That is, when the shock absorber 1 receives an external force in the pushing direction against the tip wall 71 of the small-diameter piston body 39 of the piston 5, as shown in FIG. 2 (a), the small-diameter piston body (front-stage piston body) 39 first has a large diameter. The piston body (next-stage piston body) 37 is immersed (stroked) toward the inner peripheral side.

  At this time, the small diameter piston body 39 pressurizes the working fluid in the first fluid chamber 15 by the piston surfaces 69 and 73. That is, at the beginning of the buffering operation in which the small-diameter piston body 39 strokes, the working fluid is pressurized only by the piston surfaces 69 and 73 of the small-diameter piston body 39 having a small area.

  The pressurized working fluid can flow toward the second fluid chamber 17 through the orifice 19 and generate a damping force while suppressing an increase in the drag force. The working fluid is allowed to flow toward the second fluid chamber 17 by pressurizing and contracting the accumulator 35 in the reservoir chamber 31 communicating with the second fluid chamber 17 with the working fluid. Further, since the circulation hole 21 is closed by the valve body 29 of the check valve 23, the working fluid can be reliably flowed through the orifice 19.

  Thus, when the small diameter piston body 39 is completely immersed in the inner peripheral side of the large diameter piston body 37, the piston 5 is contracted in the axial direction. In this contracted state, the tip wall 71 of the small diameter piston body 39 and the tip wall 55 of the large diameter piston body 37 are flush with each other. For this reason, the piston 5 receives an external force in the pushing direction also on the tip wall 55 of the large-diameter piston body 37. Therefore, as shown in FIG. 2B, the piston 5 is immersed (stroked) into the first fluid chamber 15 by integrating both piston bodies 37 and 39.

  At this time, the piston 5 pressurizes the working fluid by the piston surface 53 of the large diameter piston body 37 in addition to the piston surfaces 69 and 73 of the small diameter piston body 39. That is, the piston 5 can pressurize the working fluid by the piston surfaces 53, 69, 73 having an increased area as compared with the case where only the small-diameter piston body 39 is moved in and out.

  The pressurized working fluid flows to the second fluid chamber 17 side through the orifice 19 while suppressing a decrease in the flow rate. As a result, it is possible to generate a damping force while suppressing a decrease in the drag force accompanying the progress of the buffering operation.

  After the buffering operation is completed in this way, as shown in FIG. 2C, the large-diameter piston body 37 is moved together with the small-diameter piston body 39 by the urging force of the return spring 75 to return the piston 5 to the standby state. At this time, the working fluid circulates toward the first fluid chamber 15 through the circulation hole 21 and the orifice 19 opened by the valve body 29 of the check valve 23. Therefore, the shock absorber 1 can smoothly return to the standby state.

  FIG. 3 is a graph showing the relationship between the drag force and the stroke during the buffering operation. In FIG. 3, the alternate long and short dash line indicates a general single-hole shock absorber, and the solid line indicates the single-hole shock absorber of this embodiment.

  Generally, in a shock absorber, if the drag, which is a shock when an external force is applied, is made as small as possible and the drag is constant throughout the stroke, the buffering efficiency is good.

  On the other hand, as shown in FIG. 3, a general single-hole shock absorber has a large drag generated at the beginning of the buffering operation, and the drag decreases with the progress of the buffering operation, so that the buffering efficiency is extremely poor. It was.

On the other hand, the single-hole shock absorber 1 of this embodiment suppresses an excessive increase in drag force by pressurizing the small piston surfaces 69 and 73 in the initial stage of the buffering operation, and increases the piston diameter according to the progress of the buffering operation. The decrease in the drag can be suppressed by the pressure applied to the 37 piston surface 53. Therefore, the shock absorber 1 can reduce the drag when an external force is applied, and can have a substantially constant drag over the entire stroke, thereby improving the buffering efficiency.
[Effect of Example]
In the shock absorber 1 of the present embodiment, the piston 5 is supported so as to move in and out of the first fluid chamber 15 of the cylinder 3, and pressurizes and damps the working fluid by moving into and out of the first fluid chamber 15. Can generate power.

  Since the piston 5 includes multi-stage piston bodies 37 and 39 that operate integrally in the middle of the immersion movement, the overall stroke length can be shortened. As a result, the shock absorber 1 can be reduced in size as a whole by shortening the cylinder 3, can improve the degree of freedom of installation location, and can also improve the degree of freedom of design when retrofitting. it can.

  In the shock absorber 1 of the present embodiment, since the piston body 5 is provided with a large-diameter piston body 37 and a small-diameter piston body 39 in a telescoping manner, the small-diameter piston body 39 becomes a large-diameter piston body during the immersion movement. The piston bodies 37 and 39 are united by being accommodated on the inner peripheral side of 37. Therefore, in the shock absorber 1, the piston 5 in the contracted state can be finally immersed and moved into the first fluid chamber 15 while contracting the piston 5 in the axial direction, and the size can be more reliably reduced.

  Moreover, since the piston 5 can increase the piston area by operating the multi-stage piston bodies 37 and 39 integrally, it suppresses an excessive drag increase at the initial stage of the operation, and according to the progress of the operation. A decrease in drag can be suppressed by increasing the piston area.

  Therefore, the shock absorber 1 can reduce the drag when an external force is applied, and can have a substantially constant drag over the entire stroke, thereby improving the buffering efficiency. That is, the shock absorber 1 can be reduced in size while improving the buffer efficiency and ensuring the buffer performance.

  In the shock absorber 1 of the present embodiment, the piston 5 pressurizes the working fluid by the piston surfaces 69 and 73 having a small area in the small diameter piston body 39 in the initial stage of operation, and the large diameter piston body 37 and Since the working fluid is pressurized by the piston surfaces 53, 69, 73 in which the area of the small-diameter piston body 39 is increased, it is possible to surely improve the buffer efficiency.

  Further, in the shock absorber 1, since the accumulator 35 communicating with the second fluid chamber 17 is provided on the outer peripheral side of the first fluid chamber 15 and the second fluid chamber 17 of the cylinder 3, the axial size can be more reliably reduced. Can do.

In the present embodiment, since the accumulator 35 is provided between the inner and outer cylinders 7 and 9 of the cylinder 3, the accumulator 35 can be easily and reliably disposed on the outer peripheral side of the first fluid chamber 15 and the second fluid chamber 17 of the cylinder 3. it can.
Further, the shock absorber 1 of the present embodiment is provided with a step portion 45 that slides on the inner periphery of the first fluid chamber 15 of the cylinder 3 on the outer periphery of the large-diameter piston body 37, and the large-diameter piston body on the outer periphery of the small-diameter piston body 39. 37, since the step portion 61 that slides on the inner periphery is provided, the stepping movement of the piston 5 can be guided by the step portions 45 and 61.

  Therefore, the shock absorber 1 does not need to be provided with a special guide for the piston 5, can simplify the structure and can be further reduced in size.

Moreover, since the piston 5 itself receives an external force, the shock absorber 1 does not require a piston rod and can be further reduced in size.
[Modification]
The present invention is not limited to the first embodiment, and various modifications can be made. 4-7 is sectional drawing which shows the modification of the shock absorber based on Example 1 of this invention. Note that components corresponding to those in the first embodiment are denoted by the same reference numerals or A, B, C, or D, and detailed description thereof is omitted.

  The shock absorber 1A of the modification of FIG. 4 is formed by providing an accumulator 35A by movably providing a free piston 77 in the reservoir chamber 31 in place of the accumulator 35 of the shock absorber 1 of FIG. The accumulator 35 </ b> A can allow the working fluid to flow into the second fluid chamber 17 as the free piston 77 moves in the reservoir chamber 31.

  A shock absorber 1B of the modification of FIG. 5 is formed by holding an membrane 79 made of an elastic film in the reservoir chamber 31B in place of the accumulator 35 of the shock absorber 1 of FIG. 1 to form an accumulator 35B. That is, the holding part 80 of the membrane 79 formed in the inner cylinder 7B is provided on both sides of the reservoir chamber 31B. A reservoir chamber 31B is formed between the holding portions 80, and a membrane 79 is accommodated. The reservoir chamber 31B communicates with the second fluid chamber 17 through a communication passage 33B formed through the inner cylinder 7B.

  The shock absorber 1 </ b> B of this modification can allow the working fluid to flow into the second fluid chamber 17 by elastic deformation of the membrane 79.

  The shock absorber 1C of the modified example of FIG. 6 omits the partition wall 13 of the shock absorber 1 of FIG. 1 and uses the inner cylinder 7C as a partition wall. That is, in the shock absorber 1C, a first fluid chamber 15C is formed in the inner cylinder 7C, and a second fluid chamber 17C is formed between the inner and outer cylinders 7C, 9C. The inner cylinder 7C is formed with an orifice 19C and a circulating hole 21C that communicate between the first fluid chamber 15C and the second fluid chamber 17C. A recirculation valve 81 as a valve mechanism is provided in the recirculation hole 21C. The large-diameter piston body 37C of the piston 5C is provided with a protruding portion 82 that protrudes in the axial direction with respect to the stepped portion 45.

  The shock absorber 1C according to this modification can be further downsized in the axial direction.

The shock absorber 1D of the modified example of FIG. 7 omits the outer cylinder of FIG. 1 and has an accumulator 35 disposed in the second fluid chamber 17D. The shock absorber 1D of this modification can be further downsized in the width direction.
[Others]
In the above embodiment, the case where both the piston bodies 37 and 39 operate integrally by receiving the external force in the pushing direction also on the tip wall 55 of the large diameter piston body 37 has been described. A stopper member for the small-diameter piston body 39 is provided on the periphery, and both piston bodies 37 and 39 can be integrally operated via the stopper member even when only the small-diameter piston body 39 receives an external force in the pushing direction.

  In the above embodiment, the piston bodies 37 and 39 having different large and small diameters are provided in a nested manner as multistage piston bodies. For example, a plurality of piston bodies can be arranged in parallel by arranging a plurality of piston bodies having different lengths in parallel. A body may be formed.

  In the above embodiment, the piston 5 is composed of the two-stage piston bodies 37, 39. However, the piston 5 may be multistage exceeding two stages, for example, three stages or four stages.

It is sectional drawing which shows a shock absorber (Example 1). FIG. 2 is a cross-sectional view showing the operation of the shock absorber of FIG. 1 (Example 1). It is a graph which shows the relationship between the drag at the time of buffering operation | movement, and a stroke (Example 1). (Example 1) which is sectional drawing which shows the modification of a shock absorber. (Example 1) which is sectional drawing which shows the other modification of a shock absorber. It is sectional drawing which shows the further another modification of a shock absorber (Example 1). It is sectional drawing which shows the further another modification of a shock absorber (Example 1).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shock absorber 3 Cylinder 5 Piston rod 7 Inner cylinder 9 Outer cylinder 15 1st fluid chamber 17 2nd fluid chamber 19 Orifice (flow path)
21 Circulating hole 23 Check valve (valve mechanism)
33 Communication path 35 Accumulator 37 Large diameter piston body (multistage piston body)
39 Small-diameter piston body (multi-stage piston body)
53, 69, 73 Piston surface

Claims (4)

Partitioning a first fluid chamber and a second fluid chamber having an accumulator in a cylinder enclosing the working fluid;
Provided between the first fluid chamber and the second fluid chamber is a flow path communicating the both fluid chambers,
In the first fluid chamber, a piston is supported so as to move in and out,
A shock absorber that pressurizes the working fluid in the first fluid chamber by the immersive movement of the piston and allows the fluid to flow toward the second fluid chamber;
The piston is formed of a multi-stage piston body having different large and small diameters provided in a nested manner in which a small diameter piston body slides on an inner peripheral surface of a large diameter piston body opened straight to the first fluid chamber ,
The large-diameter piston body is disposed so as to be movable with respect to the first fluid chamber, and a tip wall of the large-diameter piston body can project and move from the opening of the cylinder in accordance with a retreating movement with respect to the first fluid chamber
The small-diameter piston body is formed from an opening formed in a tip wall of the large-diameter piston body within a range that moves relative to the first fluid chamber while sliding on the inner peripheral surface of the large-diameter piston body. The tip wall of the
A return spring that urges the small-diameter piston body in the projecting direction between the small-diameter piston body and the cylinder side and urges the small-diameter piston body and the large-diameter piston body to a standby state projecting from the openings. Provided,
When the tip wall of the small-diameter piston body receives an external force and moves into the opening of the tip wall of the large-diameter piston body, the piston surface of the small-diameter piston body produces an effect on the first fluid chamber. When the small-diameter piston body moves into the opening of the tip wall of the large-diameter piston body, the tip-wall of the large-diameter piston body takes over the external force and the small-diameter piston body and the large-diameter piston body move together, and the piston of the small-diameter piston body Adding a piston surface of the large-diameter piston body to a surface to generate a drag against the first fluid chamber;
Shock absorber characterized by that. The shock absorber according to claim 1,
The partition wall is provided with a circulation hole that communicates between the first fluid chamber and the second fluid chamber,
A valve mechanism that allows the working fluid to flow from the second fluid chamber to the first fluid chamber is provided in the circulation hole.
Shock absorber characterized by that. The shock absorber according to claim 1 or 2,
The accumulator is provided on the outer periphery of the first fluid chamber and the second fluid chamber,
Shock absorber characterized by that. The shock absorber according to any one of claims 1 to 3 ,
The cylinder includes an inner cylinder and an outer cylinder,
Forming a partition wall having the flow path and the first fluid chamber and the second fluid chamber in the inner cylinder;
Providing the accumulator between the inner and outer cylinders;
The inner cylinder is provided with a communication path for communicating the second fluid chamber and the accumulator.
Shock absorber characterized by that.

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