JP5550975B2 - Piston for shock absorber - Google Patents

Description

  The present invention relates to a shock absorber piston that changes a damper drag force in accordance with a moving speed of the piston.

  As a conventional shock absorber piston, for example, as in Non-Patent Document 1, there is one provided with a valve made of a disc spring in a flow path. The valve is deflected by receiving the fluid pressure of the working fluid by the movement of the piston. Due to this bending, an orifice is formed by opening the flow path, and a damper drag is generated.

  In such a shock absorber piston, when the fluid pressure changes according to the moving speed, the opening area of the orifice changes due to the deflection of the valve. Thereby, it is possible to perform the buffering operation while changing the damper drag force.

  However, the conventional structure has a problem that the shock absorber characteristics vary greatly due to variations in the elastic characteristics of the valve because the amount of deflection of the valve directly becomes the opening area of the orifice.

  In particular, the characteristics of the shock absorber are susceptible to even slight variations in the elastic characteristics of the valve because the damper drag is proportional to the square of the opening area of the orifice.

  In the conventional structure, the relationship between the opening area of the orifice and the fluid pressure has a substantially constant functional relationship, so that it is difficult to set free shock absorber characteristics.

  As described above, in the conventional structure, the elastic characteristics of the valve directly affect the shock absorber characteristics.

http://en.wikipedia.org/wiki/%E3%82%B7%E3%83%A7%E3%83%83%E3%82%AF%E3%82%A2%E3%83%96%E3 % 82% BD% E3% 83% BC% E3% 83% 90% E3% 83% BC

  The problem to be solved is that the elastic characteristics of the valve directly affect the shock absorber characteristics.

In order to be able to set the characteristics of the shock absorber without being directly affected by the elastic characteristics of the valve, the present invention is movably arranged in a cylinder filled with a working fluid and defines a pressure chamber on at least one side. A shock absorber piston, comprising: a main body portion provided with a flow path for circulating the working fluid from the pressure chamber side according to the movement; and a valve mechanism for opening and closing the flow path by the fluid pressure of the working fluid; The valve mechanism is supported so as to be movable in and out with respect to the flow path, closes the flow path by insertion movement, and forms a gap according to the withdrawal amount between the flow path and the flow path from the closed state. a valve, and the insertion tube portion which communicates with the flow path, and a biasing member for urging the valve in the insertion direction relative to the flow path, the axial center of the main body portion, b for fixing And the valve is disposed concentrically to the rod and supported to be axially movable, and the insertion tube portion is disposed concentrically to the rod to insert the valve, The insertion tube portion includes a circular seating portion at an end thereof, and the valve includes a circular seating portion that fits into the seating portion of the insertion tube portion in the closed state, and the valve seating The main feature is that the portion is seated in a circular manner on the seating portion of the insertion tube portion and closes the flow path .

  In the piston of the present invention, the valve can be pulled out against the urging force of the urging member according to the moving speed, and an orifice is formed between the valve and the flow path with a gap according to the amount of drawing. be able to.

  For this reason, the shock absorber characteristic can be set by setting a relative shape change between the valve and the flow path in accordance with the drawer movement.

(Example 1) which is sectional drawing of a shock absorber. (Example 1) which is a principal part expanded sectional view which shows the orifice of a shock absorber. (Example 2) which is sectional drawing which shows the valve | bulb of a valve mechanism. It is sectional drawing which shows the valve | bulb of the valve mechanism which concerns on a modification (Example 2). It is sectional drawing which shows the valve | bulb of the valve mechanism which concerns on another modification (Example 2).

  The purpose of enabling the shock absorber characteristics to be set without being directly affected by the elastic characteristics of the valve is realized by a valve that is supported so as to be movable in and out of the flow path.

[Composition of shock absorber]
FIG. 1 is a cross-sectional view of a shock absorber employing a piston according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part showing an orifice of the shock absorber.

  The shock absorber 1 shown in FIG. 1 is used for damping, for example, and generates a damper drag force in both a contraction operation and an extension operation. The shock absorber 1 is a so-called single cylinder type, and includes a cylinder 3, a piston 5, an image wall 7, and an accumulator 9, as shown in FIGS.

  The cylinder 3 is configured by connecting a cylindrical cylinder body 11 and an end tube portion 13. An end portion of the end tube portion 13 is screwed into the end portion of the cylinder body 11 from the outer periphery thereof. On the outer periphery of the end portion of the cylinder body 11, a seal member 15 that seals between the end cylinder portion 13 is held. A circular recess 17 is formed between the cylinder body 11 and the end tube portion 13 in the axial direction.

  Both ends of the cylinder 3 are closed by caps 19 and 21. A fluid chamber 23 filled with oil as a working fluid is defined in the cylinder 3. In the fluid chamber 23, the piston 5 is disposed so as to be movable in the axial direction via a piston rod 25 which is a fixing rod.

  The piston rod 25 is formed in a long cylindrical shape. One end 27 of the piston rod 25 is disposed in the fluid chamber 23 of the cylinder 3, and the other end 29 protrudes outside the cylinder 3 through the through hole 31 of the cap 19. Accordingly, the piston rod 25 receives an external force at the other end portion 29 so as to expand and contract with respect to the cylinder 3. A sealing member 33 for sealing is provided between the piston rod 25 and the cap 19.

  One end portion 27 of the piston rod 25 has a small diameter that forms a stepped portion 35 with respect to the other end portion 29 side. A male screw portion 37 for fastening is provided at the tip of the one end portion 27. The piston 5 is attached to one end portion 27 of the piston rod 25.

  The piston 5 defines a contraction side pressure chamber 39 as a first pressure chamber and an expansion side pressure chamber 41 as a second pressure chamber on both sides. The piston 5 includes a pair of piston bodies 43 and 45 as main body portions and valve mechanisms 47 and 49 and is configured to be point-symmetric.

  The piston bodies 43 and 45 are formed in substantially cylindrical shapes that are symmetrical to each other, and are disposed in the opposite directions in the axial direction of the piston 5. The piston bodies 43 and 45 are fastened to the one end portion 27 of the piston rod 25 by a nut 51 screwed into the male screw portion 37.

  One end portion 27 of the piston rod 25 passes through the axial center portion of the piston bodies 43 and 45 through the insertion holes 53 and 55. One side of the piston body 43 is abutted against the step portion 35 of the piston rod 25 via a ring-shaped washer 57 and a cylindrical spacer 59. The washer 57 and the spacer 59 are fitted on the outer periphery of the one end portion 27 of the piston rod 25. The other side of the one piston body 43 is abutted against the other side of the other piston body 45.

  One side of the other piston body 45 is abutted against the nut 51 via a washer 61 and a spacer 63 like the one piston body 43.

  The piston 5 is provided with piston flow paths 65 and 67. The piston flow paths 65 and 67 communicate between the pressure chambers 39 and 41 of the cylinder 3 and allow oil to flow during the contracting operation and the extending operation, respectively. The piston flow paths 65 and 67 are symmetrical with respect to the center of the piston 5.

  Each piston flow path is formed in a crank shape and includes front and rear flow path portions 69 and 71 in the oil flow direction. The front and rear flow path portions 69 and 71 are provided along the axial direction of the piston 5.

  The front flow path portion 69 is disposed on the outer peripheral side of the piston body 43 (piston body 45). The rear flow passage portion 71 is biased radially inward with respect to the front flow passage portion 69 and is disposed on the inner peripheral side of the piston body 45 (piston body 43).

  These front and rear flow passage portions 69 and 71 communicate with each other by a communication passage 73 provided along the radial direction of the piston 5. The communication path 73 is divided between the other side surfaces of the piston bodies 43 and 45.

  An insertion cylinder portion 75 is integrally provided on one side of each piston body.

  The insertion cylinder part 75 is formed in a cylindrical shape arranged concentrically with the piston rod 25. The outer periphery of the insertion cylinder part 75 is arrange | positioned inside the front flow path part 69 of the expansion | extension side piston flow path 65 (contraction side piston flow path 67). The inner circumference of the insertion cylinder portion 75 is disposed with a space from the outer circumference of the one end portion 27 of the piston rod 25.

  The inner peripheral side of the insertion cylinder part 75 communicates with the rear flow path part 71 of the contraction side piston flow path 67 (extension side piston flow path 65) of the piston body 43 (piston body 45). Therefore, the insertion cylinder part 75 comprises a part of piston flow path 67 (piston flow path 65). Further, the piston flow path 67 (piston flow path 65) communicates from the outer periphery of the contraction side insertion cylinder part 75 (extension side insertion cylinder part 75) to the inner periphery of the insertion cylinder part 75 on the opposite side.

A circular claw portion 77 is integrally formed at the axial end portion of the insertion tube portion 75 as a seating portion directed radially inward. The inner peripheral edge of the claw portion 77 protrudes in an edge shape toward the extension side pressure chamber 41 (contraction side pressure chamber 39).

  Such a piston 5 is provided with valve mechanisms 47 and 49 for opening and closing the piston flow paths 65 and 67 by the fluid pressure of oil on both sides in the axial direction. In addition, since the valve mechanisms 47 and 49 are symmetrical structures disposed in the opposite directions in the axial direction of the piston 5, only one of them will be described, and the other will be given the same reference numeral and detailed description thereof will be omitted.

  The valve mechanism 47 (valve mechanism 49) is disposed between the insertion cylinder portion 75 of the piston body 43 (piston body 45) and the washer 57 (washer 61) of the piston rod 25. The valve mechanism 47 (valve mechanism 49) includes a valve 79 and a spring 81 as an urging member in addition to the insertion tube portion 75.

The valve 79 is formed in a substantially truncated cone shape and has a tapered shape with a tapered outer peripheral surface. Accordingly, the valve 79 is a columnar body that gradually decreases in cross-sectional area from the front end side (base end side) in the pull-out direction to be described later toward the rear end side (tip end side). A circular flange 83 is provided on the proximal end side of the valve 79. The flange 83 is provided with a circular recess 85 as a seating portion .

  The valve 79 is disposed concentrically with the piston rod 25 and is inserted and supported so as to be movable in the axial direction. That is, the valve 79 is inserted and supported on the outer periphery of the spacer 59 (spacer 63) of the piston rod 25 through the insertion hole 87 in the axial center portion. The valve 79 moves in and out with respect to the insertion cylinder portion 75 by moving in the axial direction.

  That is, the valve 79 is seated with the distal end side inserted into the insertion tube portion 75 by the axial movement (insertion movement) toward the piston 5 side. At the time of seating, the concave portion 85 of the flange 83 of the valve 79 is fitted into the claw portion 77 of the insertion cylinder portion 75 to close the contraction side piston flow path 67 (extension side piston flow path 65).

  On the other hand, the valve 7 is pulled out with respect to the insertion cylinder part 75 by the axial movement (drawing movement) toward the anti-piston 5 side. By this drawing, the valve 79 forms a gap corresponding to the drawing amount between the valve 79 and the claw portion 77 of the insertion cylinder portion 75. In this embodiment, based on the tapered shape of the outer peripheral surface on the tip end side of the valve 79, the gap increases linearly as the amount of withdrawal of the valve 79 increases.

  The spring 81 is formed by connecting a plurality of disc springs in the axial direction, and is disposed between the washer 57 (washer 61) and the base end surface of the valve 79. The spring 81 is inserted and supported on the outer periphery of the spacer 59 of the piston rod 25. The spring 81 urges the valve 79 in the insertion direction into the insertion cylinder portion 75.

  In such a valve mechanism 47 (valve mechanism 49), the valve 79 moves out of the closed state against the urging force of the spring 81 by the fluid pressure of the oil in the contraction side pressure chamber 39 (extension side pressure chamber 39). . As a result, the valve mechanism 47 (valve mechanism 49) forms a piston orifice 89 (piston orifice 91) by the gap.

  In the piston orifice 89 (piston orifice 91), the opening area with respect to the fluid pressure is set according to the setting of the valve characteristic of the valve mechanism 47 (valve mechanism 49). In the present embodiment, as the valve characteristics, for example, the diameter of the valve 79, the shape or taper angle of the outer peripheral surface on the front end side, the elastic coefficient of the spring 81, the diameter of the piston channel 67 (piston channel 65), or the like is set. .

  The image wall portion 7 includes a wall body 93, a valve mechanism 95, and a relief valve 97.

  The wall body 93 is formed in a columnar shape, and the outer peripheral side is fitted in the recess 17 of the cylinder 3. Thereby, the wall body 93 is fastened and fixed between the cylinder main body 11 of the cylinder 3 and the axial direction of the end cylinder part 13. The wall body 93 partitions the reservoir chamber 99 with respect to the contraction side pressure chamber 39. The reservoir chamber 99 is disposed in series with the contraction side pressure chamber 39 in the cylinder 3.

  A hollow support tube portion 101 is provided at the axial center portion of the wall body 93. A support rod 103 is inserted into the support cylinder portion 101. One end of the support rod 103 includes a head portion 105 disposed in the contraction-side pressure chamber 39, and the other end includes a fastening male screw portion 107 disposed in the reservoir chamber 99. The support rod 103 is fastened and fixed to the support cylinder portion 101 of the wall body 93 by a nut 109 screwed into the male screw portion 107.

  One end of the support rod 103 is positioned by a ring-shaped washer 111 and a cylindrical spacer 113 interposed between the head portion 105 and one end portion of the support cylinder portion 101. The washer 111 and the spacer 113 are fitted on the outer periphery of the support rod 103. Similarly, the other end of the support rod 103 is positioned by a washer 111 and a spacer 113 interposed between the nut 109 and the other end of the support cylinder portion 101.

  A reservoir channel 115 is formed through the outer periphery of the support cylinder portion 101. An annular channel 117 is formed through the outer periphery of the reservoir channel 115. The reservoir channel 115 and the annular channel 117 communicate between the contraction-side pressure chamber 39 and the reservoir chamber 99, and can flow oil corresponding to the volume change caused by the expansion / contraction operation of the piston rod 25.

  An insertion tube portion 119 is integrally provided on the wall body 93 on the reservoir chamber 99 side.

  The insertion cylinder part 119 is configured in the same manner as the insertion cylinder part 75 of the piston 5. This insertion cylinder part 119 is formed in a cylindrical shape having a smaller diameter than the insertion cylinder part 75 on the piston 5 side. The inner peripheral side of the insertion tube portion 119 communicates with the reservoir channel 115 and constitutes a part of the reservoir channel 115.

  An edge-shaped claw portion 121 directed inward in the radial direction is provided in a circular shape at the axial end portion of the insertion tube portion 119. A valve mechanism 95 that opens and closes the reservoir channel 115 is provided between the insertion tube portion 119 and the washer 111 of the support rod 103.

  The valve mechanism 95 is configured similarly to the valve mechanisms 47 and 49 on the piston 5 side, and includes a valve 125 and a spring 127 as an urging member in addition to the insertion tube portion 119.

  The valve 125 is formed in a substantially truncated cone shape having a smaller diameter than the valve 79 on the piston 5 side. The outer peripheral surface of the valve 125 has a tapered shape with a smaller inclination angle than the valve 79 on the piston 5 side. The flange 131 on the proximal end side of the valve 125 is provided with a circular recess 129.

  The valve 125 is inserted through and supported by the outer periphery of the spacer 113 of the support rod 103 through an insertion hole 133 in the axial center portion so as to be movable in the axial direction. With this axial movement, the valve 125 moves in and out with respect to the insertion tube portion 119.

  That is, like the valve 79 on the piston 5 side, the valve 125 is seated by being inserted into the insertion tube portion 119 and closes the reservoir channel 115. Moreover, the valve | bulb 125 forms the clearance gap according to the drawing | extracting amount between the nail | claw part 121 of the insertion cylinder part 119 by the drawer | drawing-out movement from the insertion cylinder part 119. FIG. In this embodiment, based on the tapered shape of the outer peripheral surface on the front end side of the valve 125, the gap increases linearly with an increase in the pulling amount of the valve 125.

  The spring 127 is formed by connecting a plurality of disc springs in the axial direction, and is disposed between the washer 111 and the base end surface of the valve 125. The spring 127 is inserted into and supported by the outer periphery of the spacer 113 of the piston rod 25 and urges the valve 125 in the direction of insertion into the insertion tube portion 119.

  In the valve mechanism 95, like the valve mechanism 47 on the piston 5 side, the valve 125 performs a pulling movement with respect to the closed state against the urging force of the spring 127 by the fluid pressure of the oil in the contraction side pressure chamber 39. As a result, the valve mechanism 95 forms a reservoir orifice 135 by the gap.

  The reservoir orifice 135 has an opening area with respect to fluid pressure set by the valve characteristic of the valve mechanism 95. As the valve characteristics, for example, the diameter of the valve 125, the outer peripheral shape or taper angle on the tip side, the elastic coefficient of the spring 127, the diameter of the reservoir channel 115, or the like is set.

  In the setting of the opening area, the opening area ratio of the piston orifice 89 that receives fluid pressure from the reservoir orifice 135 and the same contraction side pressure chamber 39 is set to be equal to or less than the cross-sectional area ratio of the piston rod 25 and the piston 5. .

  The relief valve 97 is provided on the contraction side pressure chamber 39 side of the wall body 93. The relief valve 97 is formed in a disk shape, and is inserted and supported on the outer periphery of the spacer 113 of the support rod 103 through an insertion hole 137 in the axial center portion so as to be movable in the axial direction.

  The relief valve 97 is urged toward the wall 93 by a return spring 139 interposed between the support rod 103 and the washer 111.

  Accordingly, the relief valve 97 moves in the axial direction against the urging force of the return spring 139 to open and close the annular flow path 117. In the closed state, the reservoir channel 115 is opened by the through hole 141 formed through the relief valve 97.

  The accumulator 9 is provided on the reservoir chamber 99 side, and includes a free piston 143 and a back space 145.

  The free piston 143 divides the fluid chamber 23 and divides the reservoir chamber 99 between the free piston 143 and the drawing wall portion 7. The free piston 143 is fitted to the inner periphery of the end tube portion 13 of the cylinder 3 so as to be axially movable. On the outer periphery of the free piston 143, a seal member 147 for sealing between the inner periphery of the end tube portion 13 is held.

  The free piston 143 is urged toward the reservoir chamber 99 by a return spring 149 interposed between the cap 21 of the end tube portion 13 on the back side. Note that the return spring 149 can be omitted, and the urging force is set so that the fluid chamber 23 does not become a high pressure.

  A back space 145 is provided on the back side of the free piston 143. The back space 145 is open to the atmosphere through the through holes 151 and 152 of the cap 21.

The accumulator 9 absorbs the volume change of the fluid chamber 23 as the free piston 143 moves in the axial direction.
[Action of shock absorber]
First, each operation | movement of the valve mechanism 47 and the valve mechanism 95 and operation | movement of the shock absorber 1 by this are demonstrated.

  In the shock absorber 1 of the present embodiment, the damper effect is generated when the contracting operation and the extending operation are performed.

  When the other end 29 of the piston rod 25 receives an external force in the pushing direction from the buffer object, the piston rod 25 contracts. In conjunction with this operation, the piston 5 moves to the contraction side pressure chamber 39 side. In response to this movement, one valve mechanism 47 of the piston 5 operates to generate a damper effect.

  The valve 79 of the valve mechanism 47 receives the fluid pressure of oil from the contraction side pressure chamber 39 via the contraction side piston channel 67 and the insertion cylinder part 75 according to the moving speed of the piston 5. As a result, the valve 79 moves in the axial direction against the urging force of the spring 81 and is pulled out from the insertion tube portion 75.

  A piston orifice 89 based on the taper shape of the valve 79 is formed between the valve 79 and the inner peripheral edge of the claw portion 77 of the insertion cylinder portion 75 according to the amount of withdrawal. Therefore, in the shock absorber 1, oil can be moved from the contraction side pressure chamber 39 side to the expansion side pressure chamber 39 side via the piston orifice 89, and a damper effect corresponding to the opening area of the piston orifice 89 can be generated.

  On the other hand, the volume of the fluid chamber 23 decreases as the piston rod 25 is inserted. The excess oil at this time operates the valve mechanism 95 of the drawing wall 7.

  That is, the valve 125 of the valve mechanism 95 controls the fluid pressure of oil from the contraction side pressure chamber 39 via the reservoir channel 115 and the insertion cylinder portion 119 in accordance with the moving speed of the piston 5, similarly to the valve mechanism 47 of the piston 5. receive.

  Thus, the valve 125 moves in the axial direction against the urging force of the spring 127, and forms a reservoir orifice 135 based on the tapered shape of the outer peripheral surface on the distal end side with the insertion tube portion 119 according to the amount of withdrawal.

  Therefore, in the shock absorber 1, excess oil can be moved from the contraction side pressure chamber 39 side to the reservoir chamber 99 side via the reservoir orifice 135. In the reservoir chamber 99, the free piston 143 of the accumulator 9 can move in the axial direction against the urging force of the return spring 149 to absorb the volume change.

  When the other end portion 29 of the piston rod 25 receives an external force in the pulling direction from the buffer object, the piston rod 25 extends. In conjunction with this operation, the piston 5 moves to the extension pressure chamber 39 side. In response to this movement, the other valve mechanism 49 of the piston 5 operates to generate a damper effect as in the contraction operation.

  At this time, the volume of the fluid chamber 23 increases due to the protrusion of the piston rod 25 to the outside. For this reason, the relief valve 97 of the wall 7 is opened against the urging force of the return spring 139 on the contraction side pressure chamber 39 side, and oil is drawn from the reservoir chamber 99 side.

  In the reservoir chamber 99, the free piston 143 of the accumulator 9 can move in the axial direction by the atmospheric pressure and the urging force of the return spring 149 to absorb the volume change in response to the oil drawing.

  Next, the operation relationship between the valve mechanisms 47 and 95 will be described.

  During the contraction operation of the piston rod 25, the oil tends to move simultaneously from the contraction side pressure chamber 39 to the extension side pressure chamber 39 side and the reservoir chamber 99 side.

  Therefore, the valve 79 of the valve mechanism 47 opens the piston flow path 67 to form the piston orifice 89 as described above, and the valve 125 of the valve mechanism 95 opens the reservoir flow path 115 to form the reservoir orifice 135. To do.

  At this time, a pressure difference ΔP is generated between the contraction side pressure chamber 39 and the reservoir chamber 99 due to the orifice resistance of the reservoir orifice 135. Here, the pressure in the reservoir chamber 99 is zero at the gauge pressure because the back space 145 of the free piston 143 is open to the atmosphere. As a result, a pressure P corresponding to the pressure difference ΔP is generated in the contraction side pressure chamber 39.

  If this pressure P (pressure difference ΔP) is equal to or greater than the pressure difference ΔP ′ due to the piston orifice 89, no negative pressure is generated on the expansion side pressure chamber 39 side, and oil can be properly circulated through the piston orifice 89. .

  In general, the pressure difference is proportional to the square of the flow velocity. Therefore, in order to make ΔP equal to or larger than ΔP ′, the flow velocity v of the reservoir orifice 135 needs to be set to be equal to or larger than the flow velocity V of the piston orifice 89 (v ≧ V).

  Here, the oil flowing through the piston orifice 89 and the reservoir orifice 135 is the moving volume integral of the piston 5, and the oil flowing through the reservoir orifice 135 is a surplus corresponding to the insertion volume of the piston rod 25. .

  In addition, the flow rate increases as the flow path area decreases in the case of a predetermined flow rate.

  For this reason, the reservoir orifice 135 may be set to be equal to or smaller than the opening area obtained by reducing the piston orifice 89 according to the cross-sectional area ratio between the piston 5 and the piston rod 25. With this setting, the flow rate of the reservoir orifice 135 can be made equal to or higher than the flow rate of the piston orifice 89.

Therefore, the condition for v ≧ V is as follows when the opening area of the reservoir orifice 135 is b, the opening area of the piston orifice 89 is B, the sectional area of the piston rod 25 is a, and the sectional area of the piston 5 is A. Formula b ≦ (a / A) × B Formula (1)
It can be expressed as

When this is expressed as a dimensional ratio, the following formula b / B ≦ a / A formula (2)
It can be.

  As described above, in this embodiment, the area ratio b / B of the reservoir orifice 135 of the valve 95 and the piston orifice 89 of the valve 47 is set to be equal to or less than the sectional area ratio a / A of the piston rod 25 and the piston 5. Yes.

  As a result, in this embodiment, the flow velocity of the reservoir orifice 135 can be made higher than the flow velocity of the piston orifice 89. Thereby, even if the back space 145 of the free piston 143 is open to the atmosphere, the oil can be properly circulated through the piston orifice 89 and an appropriate damper drag can be generated.

When the flow velocity v is higher than the flow velocity V, the pressure P + α can be generated by the gauge pressure in the contraction side pressure chamber 39, and the pressure α can be generated by the gauge pressure in the extension side pressure chamber 39. Further, when the flow velocity v is equal to the flow velocity V, the pressure in the extension side pressure chamber 39 can be made zero by the gauge pressure.
[Effect of Example 1]
The piston 5 of the present embodiment is a shock absorber piston that is movably disposed in a cylinder 3 filled with oil as a working fluid and that defines a pressure chamber 39 on at least one side. Piston bodies 43 and 45 as body portions having a piston flow path 67 through which oil is circulated, and a valve mechanism 47 that opens and closes the piston flow path 67 by the flow of oil.

  Further, the valve mechanism 47 is supported so as to be movable in and out with respect to the piston flow path 67, closes the piston flow path 67 by insertion movement, and responds to the pull-out amount between the piston flow path 67 and the piston flow path 67 by movement of withdrawal. And a spring 81 as an urging member for urging the valve 79 in the insertion direction with respect to the piston flow path 67.

  Therefore, in this embodiment, the valve 79 of the valve mechanism 47 is pulled out from the piston flow path 67 according to the moving speed of the piston 5, and the piston formed by the gap between the valve 79 and the piston flow path 67 according to the pull-out amount. An orifice 89 can be formed.

  For this reason, in this embodiment, the opening area of the piston orifice 89 corresponding to the moving speed of the piston 5 can be set by setting a relative shape change between the valve 79 and the piston flow path 67 accompanying the drawing. it can.

  As a result, the characteristics of the shock absorber 1 can be set without being directly affected by the elastic characteristics of the valve 79 and the spring 81.

  In particular, in this embodiment, even if the elastic characteristic of the spring 81 varies, it can be absorbed by the setting of the shape change, and the characteristic of the shock absorber 1 can be stabilized.

  In the present embodiment, the shock absorber characteristics can be freely set regardless of the elastic characteristics of the valve 79 and the spring 81 by setting the shape change.

  The piston 5 has a piston rod 25 for fixing passing through the axial center of the piston bodies 43 and 45, and the valve 79 is concentrically disposed on the piston rod 25 and inserted and supported so as to be movable in the axial direction. The valve mechanism 47 includes an insertion cylinder portion 75 that is in communication with the piston flow path 67 and is disposed concentrically with the piston rod 25 and into which the valve 79 is inserted.

  For this reason, the valve 79 can be moved in and out of the channel 67 and the shape change can be set more easily and reliably.

  In the present embodiment, the end portion of the insertion cylinder portion 75 is provided with a circular claw portion 77, and the valve 79 is provided with a circular recess portion 85 fitted to the claw portion 77 of the insertion cylinder portion 75 in the closed state. The stability in the state can be improved and the shape change can be set more easily and reliably.

  The valve 79 is a columnar body (conical frustum shape) that gradually decreases in cross-sectional area from the front end (base end) side to the rear end (tip end) side in the pull-out direction. A gap can be formed.

  The piston 5 of this embodiment is point-symmetric with valve mechanisms 47 and 49 on both sides, and a pair communicating from the outer peripheral side of the insertion cylinder part 75 of each valve mechanism to the inner peripheral side of the insertion cylinder part 75 of the opposite valve mechanism. The flow paths 65 and 67 are provided.

  For this reason, while the piston 5 can be manufactured easily and inexpensively, the damper effect based on the setting of the shape change can be reliably generated in both the contraction operation and the extension operation.

  Further, the area ratio of the reservoir orifice 135 and the piston orifice 89 is set to be equal to or smaller than the cross-sectional area ratio of the piston rod 25 and the piston 5.

  Therefore, in the shock absorber 1, the pressure difference between the reservoir chamber 99 and the contraction side pressure chamber 39 can be made larger than the pressure difference between the pressure chambers 39 and 41. For this reason, it is possible to reliably generate the damper effect by the expansion and contraction operation without using the high pressure gas for the accumulator 9. As a result, in the single cylinder type shock absorber 1, it can suppress that an inside becomes a high voltage | pressure.

  Therefore, the single-cylinder shock absorber 1 can suppress the generation of repulsive force against the piston rod and frictional force due to tightening of the seal member, and the piston 5 is positioned at the neutral position during normal vibration control. It can be used as a cylindrical shock absorber.

  Moreover, since the shock absorber 1 is a single cylinder type, the piston diameter with respect to the same volume can be expanded to obtain a larger damping force, and the heat dissipation is good, and it can also be used in the horizontal direction. .

  Thus, in the shock absorber 1 of the present embodiment, the same shock absorber characteristic as that of the double cylinder type can be obtained while being a single cylinder type.

  The ratio between the reservoir orifice 135 and the piston orifice 89 is set by the valve characteristics of the valve mechanisms 95 and 47. For this reason, in the shock absorber 1 of a present Example, the setting of the said ratio can be performed easily and reliably.

  Embodiment 2 of the present invention will be described below with reference to FIGS. 3 is a sectional view showing a valve of a valve mechanism according to a second embodiment of the present invention, FIG. 4 is a sectional view showing a valve according to a modification, and FIG. 5 is a sectional view showing a valve according to another modification. FIG. The basic configuration of the present embodiment is the same as that of the first embodiment, and corresponding components are denoted by the same reference numerals or the same reference numerals with A, B, or C, and detailed description thereof is omitted.

  The valve 79A (125A) in FIG. 3 has a tapered shape on the outer peripheral surface as a quadratic curve in which the increase amount of the gap gradually increases in accordance with the pulling amount.

  The valve 79B (125B) in FIG. 4 has a tapered shape on the outer peripheral surface as a quadratic curve in which the increase amount of the gap gradually decreases in accordance with the pulling amount.

  A valve 79C (125C) in FIG. 5 is provided with a recess 153 on the outer peripheral surface to change the shock absorber characteristics during the withdrawal.

  Note that the shape of the outer peripheral surface may be set in a wavy shape as a whole by appropriately combining a tapered shape, a quadratic curve, and a concave portion, or by providing a plurality of concave portions 153 according to the shock absorber characteristics.

Also in this embodiment, the same effects as those of the first embodiment can be obtained.
[Others]
As mentioned above, although the Example of this invention was described, this invention is not limited to this, Various design changes are possible.

  For example, in the above embodiment, the present invention is applied to a single cylinder type shock absorber, but the present invention may be applied to a double cylinder type shock absorber.

  Further, in the above embodiment, the gap between the flow path side is set by setting the shape of the valves 79 and 125, but conversely, the gap can be set by setting the shape on the flow path side.

  The valves 79 and 125 move in and out of the insertion cylinder portions 75 and 119. However, even if the insertion cylinder portions 75 and 119 are omitted and the valves 79 and 125 move directly in and out of the piston flow paths 65 and 67 and the reservoir flow path 115, they move. Good.

  Further, as the urging members of the valve mechanisms 47 and 49.95, it is sufficient that the valves 79 and 125 can be urged. Therefore, other urging members such as a spring from a coil spring can be used.

  In the above embodiment, the damper drag force is generated in both the contraction operation and the extension operation. However, for example, the damper effect may be generated only during the contraction operation. Such a configuration can be easily realized by omitting the spring 81 of the valve mechanism 49 of the piston 5. In this case, it can replace with the accumulator 9, and can also arrange | position the accumulator as an independent foaming elastic body in a non-pressure chamber (41).

  Further, the accumulator is not limited to the above-described embodiment, and other types of accumulators may be used.

DESCRIPTION OF SYMBOLS 1 Shock absorber 3 Cylinder 5 Piston 39, 41 Pressure chamber 43, 45 Piston body 47, 49 Valve mechanism 65, 67 Piston flow path (flow path)
75 Insertion cylinder portion 77 Claw portion 79 Valve 81 Spring (biasing member)

Claims (6)

In a shock absorber piston movably disposed in a cylinder filled with a working fluid and defining a pressure chamber on at least one side,
A main body having a flow path for circulating the working fluid from the pressure chamber side in accordance with the movement;
A valve mechanism that opens and closes the flow path by the fluid pressure of the working fluid,
The valve mechanism is supported so as to be movable in and out with respect to the flow path, closes the flow path by insertion movement, and forms a gap according to the withdrawal amount between the flow path and the flow path from the closed state. A valve, an insertion tube portion communicating with the flow path, and a biasing member that biases the valve in the insertion direction with respect to the flow path,
A fixing rod passes through the axial center of the main body,
The valve is concentrically disposed on the rod and inserted and supported so as to be axially movable,
The insertion tube portion is arranged concentrically with the rod to insert the valve,
The insertion tube portion includes a circular seating portion at an end thereof,
The valve includes a circular seated portion that fits into the seating portion of the insertion tube portion in the closed state,
The seated portion of the valve is seated in a circular manner on the seating portion of the insertion tube portion and closes the flow path;
This is a shock absorber piston. The shock absorber piston according to claim 1 ,
The seating portion of the insertion tube portion is a circular claw portion at an end thereof,
The seated portion of the valve is a circular recess that fits into the claw portion of the insertion tube portion in the closed state.
This is a shock absorber piston. The shock absorber piston according to claim 1 or 2 ,
The valve is a columnar body that gradually decreases in cross-sectional area from the front end side to the rear end side in the pull-out direction.
This is a shock absorber piston. A shock absorber piston according to any one of claims 1 to 3,
The main body portion includes the valve mechanisms on both sides in the axial direction, and includes a pair of flow paths communicating from the outer peripheral side of the insertion tube portion of each valve mechanism to the inner peripheral side of the insertion tube portion of the opposite valve mechanism.
This is a shock absorber piston. The shock absorber piston according to claim 4 ,
The main body portion includes a pair of piston bodies provided with the valve mechanism on one side and the other side abutted against each other.
This is a shock absorber piston. A shock absorber piston according to any one of claim 1 to 5
The biasing member is a spring.
This is a shock absorber piston.