JP2007192283A - Shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a variation in drag due to surge and a variation in temperature. <P>SOLUTION: This shock absorber 1 comprises a cylinder 3 in which a viscous liquid is sealed and a liquid chamber 9 is formed, a piston 5 movably disposed in the liquid chamber 9, and an orifice 7 allowing the viscous liquid to pass therethrough to allow the piston 5 to move while imparting a drag to the piston. The orifice 7 comprises a thin blade part 11 circumferentially formed on the inner periphery of the cylinder 3 and a tapered part 23 formed on the outer periphery of the piston 5 and gradually changing a passage area formed between itself and the thin blade part 11 according to the moving stroke of the piston 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shock absorber.

  As a conventional shock absorber, as disclosed in Patent Document 1, there is one in which an orifice having a small hole is formed penetrating in the radial direction of the piston, and a plurality of such orifices are continuously provided in the moving direction of the piston. In this shock absorber, when the piston moves at the time of impact input, viscous liquid can flow from the pressure chamber to the non-pressure chamber through the orifice to absorb the shock.

  However, in such a structure, the orifice is sequentially closed with the movement of the piston to increase the drag, so that there is a fluctuation in the drag due to a surge when the viscous liquid passes through the orifice. Since the piston is inserted into the small diameter part of the cylinder when the piston moves and the orifice is sequentially closed, the length of the piston in the viscous liquid flow direction that receives the viscous resistance of the viscous liquid (hereinafter referred to as “viscous length” ”), Which is easily affected by changes in the viscosity resistance due to temperature, and there is a problem that the drag fluctuates due to temperature changes.

JP 2001-198228 A JP 2003-14027 A

  The problem to be solved is that the drag fluctuates due to surge and temperature change.

  The present invention provides a cylinder that encloses a viscous liquid to form a liquid chamber, a piston that is movably disposed in the liquid chamber, and the viscous liquid so as to suppress drag fluctuations due to surges and temperature changes. In the shock absorber having an orifice that allows the piston to move while allowing the piston to pass through, the orifice is formed on the inner periphery of the cylinder in a circular shape and on the outer periphery of the piston. The main feature is that the passage area formed between the thin blade portions is composed of an inclination changing portion that gradually changes the inclination according to the movement stroke of the piston.

  The shock absorber according to the present invention includes a cylinder that encloses a viscous liquid to form a liquid chamber, a piston that is movably disposed in the liquid chamber, and a fluid that passes through the viscous liquid and imparts resistance to the piston. A shock absorber having an orifice that allows the orifice to pass between the thin blade portion formed in a circular shape on the inner periphery of the cylinder and the thin blade portion formed on the outer periphery of the piston. Since the area is composed of an inclination changing section that gradually changes the inclination according to the movement stroke of the piston, the passage area can be continuously changed, and drag fluctuation due to surge can be suppressed. In addition, the passage area is changed by the thin blade portion and the inclined changing portion, and the viscosity length of the piston in contact with the viscous liquid does not change, so that it is difficult to be affected by the viscous resistance and the drag fluctuation due to the temperature change can be suppressed.

  The purpose of making it possible to suppress drag fluctuations due to surges and temperature changes has been realized by the thin blade part and the inclined change part.

[Shock absorber structure]
1 is a cross-sectional view of a shock absorber according to a first embodiment of the present invention.

  As shown in FIG. 1, the shock absorber 1 includes a cylinder 3, a piston 5, and an orifice 7.

  The cylinder 3 is formed of a drawn steel pipe or the like, and forms a liquid chamber 9 by enclosing a viscous liquid such as oil. A thin blade portion 11 is formed in a circular shape on the inner periphery of the cylinder 3. The thin blade portion 11 is provided with cut portions 13a and 13b to make the viscosity length of the thin blade portion 11 shorter. The cross-sectional shape of the thin blade portion 11 can be variously selected depending on the setting of the cut portion, such as a step shape or a double taper (both sides inclined) shape.

  The piston 5 is integrally provided with a piston rod 15 and is movably disposed in the liquid chamber 9. In the piston 5, several slits 17 in the circumferential direction are formed on the outer periphery on the base side, and the pressure chamber 19 and the non-pressure chamber 21 are communicated with each other. A taper portion 23 is provided in the range of the length L as an inclination changing portion on the outer periphery on the front end side of the piston 5. Therefore, in this embodiment, the inclination of the inclination changing portion means the taper size of the taper portion 23. A return spring 25 is interposed between the cylinder 3 and the piston 5.

  The orifice 7 allows movement while allowing a viscous liquid to pass through and applying a drag force to the piston 5, and is constituted by the thin blade portion 11 and the taper portion 23. The orifice 7 is configured such that the passage area formed between the thin blade portion 11 and the taper portion 23 is gradually inclined according to the movement stroke of the piston 5. In this embodiment, when the piston 5 moves in the cylinder 3, the inclination is changed so as to gradually reduce the passage area according to the movement stroke, and the thin blade portion 11 is fitted to the outer periphery 27 of the general portion of the piston 5. The area is almost zero. Therefore, the inclination change means that the passage area of the orifice 7 gradually decreases in accordance with the movement of the piston 5 in this embodiment.

[Shock absorption]
When there is an impact input from the object to be controlled to the piston rod 15, a force is transmitted from the piston rod 15 to the piston 5, and the piston 5 moves relative to the cylinder 3.

  Due to the movement of the piston 5, the viscous liquid in the pressure chamber 19 flows through the orifice 7 to the non-pressure chamber 21 side, and the movement of the piston 5 is allowed. When the viscous liquid passes through the orifice 7, a drag force is applied to the piston 5 by the dynamic pressure resistance to restrict its movement, and the input impact is alleviated. At this time, since the inclination of the passage area of the orifice 7 gradually decreases according to the movement stroke of the piston, the dynamic pressure resistance acting on the piston 5 gradually increases.

  When the movement stroke of the piston 5 is increased and the outer periphery 27 of the general part is fitted to the thin blade part 11, the passage area becomes almost zero and the locked state is established.

  When there is no input from the object to be controlled to the piston rod 15, the piston 5 is pushed back to the non-pressure chamber 21 side by the urging force of the return spring 25 and returns to the original state.

[Effect of Example 1]
The shock absorber 1 according to the first embodiment of the present invention includes a cylinder 3 that encloses a viscous liquid to form a liquid chamber 9, a piston 5 that is movably disposed in the liquid chamber 9, and a piston that allows the viscous liquid to pass therethrough. In the shock absorber 1 provided with an orifice 7 that allows movement while applying a drag to the orifice 5, the orifice 7 is formed on the inner periphery of the cylinder 3 in a circular shape and the outer periphery of the piston 5 is formed on the outer periphery of the piston 5. The passage area formed with the portion 11 is composed of a tapered portion 23 that gradually changes the slope according to the movement stroke of the piston 5, so that the passage area can be continuously changed in inclination, and fluctuations in drag due to surge are suppressed. can do. Further, the passage area is changed by the thin blade portion 11 and the taper portion 23, and the viscosity length of the piston 5 in contact with the flowing viscous liquid does not change. And drag fluctuation can be suppressed. By suppressing these drag fluctuations, the shock absorption characteristics of the shock absorber 1 can be stabilized.

  A design in which the cylinder 3 is formed of a drawn steel pipe is also possible and can be manufactured at low cost.

  The tapered portion 23 of the piston 5 can be formed on an arbitrary tapered surface including a curved surface by an NC control machine tool, and the degree of freedom in design can be expanded.

  FIG. 2 relates to the second embodiment of the present invention, and both (a) and (b) are cross-sectional views of the thin blade portion. The thin blade portion 11A shown in FIG. 2A has a circumferential groove 27 formed in a circular shape on the inner circumferential surface of the cylinder 3A, and a piston ring 29 fitted and fixed to the circumferential groove 27 as a ring member having a rectangular cross section. is there. As the material of the piston ring 29, cast iron, Teflon (registered trademark) (including a filler), or the like is used.

  Even in the structure of FIG. 2A, the same effect as in the first embodiment can be obtained.

  Moreover, since the thin blade portion 11A can be configured by providing the circumferential groove 27 on the cylinder 3A side, the processing on the cylinder 3A side becomes easier.

  FIG. 2B shows a thin blade portion 11 </ b> B provided with a cut portion 31 in the piston ring 29.

  By providing the cut part 31, the viscosity length which contacts a viscous liquid can be shortened, and it can make it less susceptible to the change by the temperature of viscous resistance.

  3A and 3B relate to a third embodiment of the present invention, in which FIG. 3A is a sectional view of a piston, and FIG. 3B is an end view thereof.

  As shown in FIGS. 3A and 3B, in this embodiment, the inclination changing portion of the piston 5 </ b> C is the depth inclined groove portion 33. The depth inclined groove portion 33 is obtained by changing the groove depth, and is set to gradually become deeper from the base side to the tip side of the piston 5C. Therefore, the inclination of the inclination change part of a present Example means the change of groove depth. The outer diameter on the tip side of the piston 5 </ b> C is set to be equal to the outer diameter of the general portion outer periphery 27. However, the outer diameter on the tip side can be formed slightly smaller than the outer diameter of the outer periphery 27 of the general part.

  Accordingly, the thin blade portions 11, 11A, 11B are positioned on the shallow side of the depth inclined groove portion 33 according to the moving stroke of the piston 5C, and the passage area can be continuously changed. Can produce various effects. In addition, since the passage area of the orifice 7 is changed by changing the groove depth, the drag can be easily adjusted by changing the groove depth and setting the number of grooves.

  FIG. 4 is a plan view of the piston according to the fourth embodiment of the present invention.

  As shown in FIG. 4, in this embodiment, the inclined change portion of the piston 5 </ b> D is a width inclined groove portion 35. The width-inclined groove portion 35 is obtained by changing the groove width, and is set so as to gradually increase from the base side to the tip side of the piston 5D. Therefore, the inclination of the inclination changing part of the present embodiment means a change in the groove width. The outer diameter on the tip side of the piston 5D is set to be equal to the outer diameter of the outer periphery 27 of the general part. However, the outer diameter on the tip side can be formed slightly smaller than the outer diameter of the outer periphery 27 of the general part.

  Accordingly, the thin blade portions 11, 11A, 11B are positioned on the narrower side of the width inclined groove portion 35 in accordance with the moving stroke of the piston 5D, and the passage area can be continuously changed. Can be played. In addition, since the passage area of the orifice 7 is changed by changing the groove width, the drag can be easily adjusted by changing the groove width and setting the number of grooves.

  The inclination change part of the piston can be a combination of the structures of the fourth and fifth embodiments. That is, instead of the depth inclined groove portion 33 and the width inclined groove portion 35, a depth width inclined groove portion that changes the groove depth and the groove width is used. The depth width inclined groove portion is obtained by changing the groove depth and the groove width, and is set so as to gradually become deeper and gradually wider from the base side to the tip side of the piston. Therefore, the inclination of the inclination change part of the present embodiment means a change in groove depth and groove width.

  In this embodiment, the passage area can be changed more steeply in a limited length.

(Example 1) which is sectional drawing of a shock absorber. (A) (b) is sectional drawing of a thin blade part (Example 2). (A) is sectional drawing of a piston, (b) is an end elevation of a piston (Example 3). (Example 4) which is a top view of a piston.

Explanation of symbols

1 Shock absorber 3, 3A, 3B Cylinder 5, 5C, 5D Piston 7 Orifice 9 Liquid chamber 11, 11A, 11B Thin blade part 23 Tapered part (inclination changing part)
27 Circumferential groove 29 Piston ring (ring member)
33 Depth inclined groove (inclination changing part)
35 width inclined groove (inclination changing part)

Claims (6)

A cylinder enclosing a viscous liquid to form a liquid chamber;
A piston movably disposed in the liquid chamber;
In a shock absorber comprising an orifice that allows movement while allowing the viscous liquid to pass through and applying drag to the piston,
The orifice gradually changes the inclination of the passage area formed between the thin blade portion formed in a circular shape on the inner periphery of the cylinder and the thin blade portion formed on the outer periphery of the piston in accordance with the moving stroke of the piston. A shock absorber characterized by comprising a slope change part. The shock absorber according to claim 1,
The shock absorber is characterized in that the slope changing portion is a tapered portion. The shock absorber according to claim 1,
The shock absorber is a depth-inclined groove portion that changes the groove depth. The shock absorber according to claim 1,
The shock absorber is a width-inclined groove that changes the groove width. The shock absorber according to claim 1,
The shock absorber is a depth-width inclined groove part that changes the groove depth and groove width. The shock absorber according to any one of claims 1 to 5,
The thin blade portion is composed of a ring member fitted and fixed to a circumferential groove formed on the inner peripheral surface of the cylinder.

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