JP5550980B2 - Single cylinder shock absorber - Google Patents

Description

  The present invention relates to a single cylinder type shock absorber.

  As a conventional single-cylinder shock absorber, for example, as in Non-Patent Document 1, there is a cylinder in which a fluid chamber and a gas chamber are partitioned by a free piston. The gas chamber constitutes an accumulator that encloses the high-pressure gas and absorbs the volume change in the fluid chamber together with the free piston.

  In such a single-cylinder shock absorber, the free piston is biased toward the fluid chamber by the gas pressure, so that it is possible to reliably generate a damper drag during the contraction operation while absorbing the volume change in the fluid chamber.

  However, the conventional structure has a problem that the pressure in the entire fluid chamber is increased by the gas pressure, and a repulsive force or a frictional force due to tightening of the seal member is generated on the piston rod.

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 fluid chamber is at a high pressure in order to generate a damper drag during expansion and contraction.

  The present invention is arranged so as to be movable in a cylinder filled with a working fluid in order to generate a damper drag during expansion and contraction while suppressing a high pressure in the fluid chamber, and a first fluid chamber and a second fluid chamber on both sides. A piston rod that extends and contracts with respect to the inside of the cylinder and interlocks the piston, and at least the piston rod is moved toward the first fluid chamber by contraction movement of the piston rod. Accordingly, a partition that partitions a piston orifice that allows the working fluid to flow from the first fluid chamber to the second fluid chamber, and a reservoir chamber that can absorb a volume change due to contraction movement of the piston rod with respect to the first fluid chamber. And a reservoir orifice that is provided in the partition wall and allows the working fluid corresponding to the volume change to flow from the first fluid chamber to the reservoir chamber. , The area ratio of the reservoir orifice and the piston orifice, and most main feature that it is set below the cross-sectional area ratio of the piston rod and the piston.

  In the present invention, by setting the area ratio between the reservoir orifice and the piston orifice, the pressure difference between the reservoir chamber and the first fluid chamber during the contraction operation can be made larger than the pressure difference between the first and second fluid chambers. . For this reason, it can suppress that an inside becomes a high voltage | pressure, being able to generate | occur | produce a damper effect reliably.

It is sectional drawing of a single cylinder type shock absorber (Example 1). It is a principal part expanded sectional view which shows the outline of an orifice, (a) has shown the piston orifice (b) has shown the reservoir orifice (Example 1). (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). (Example 3) which is a principal part expanded sectional view of a single cylinder type shock absorber. (Example 4) which is sectional drawing of a single cylinder type shock absorber. (Example 5) which is a principal part expanded sectional view of a single cylinder type shock absorber. (Example 5) which is a principal part expanded sectional view which concerns on the modification of a single cylinder type shock absorber. (Example 6) which is a schematic sectional drawing which shows a single cylinder type shock absorber.

  The objective of generating damper drag during expansion and contraction while suppressing high pressure in the fluid chamber has been realized with a simple structure.

[Configuration of single cylinder shock absorber]
1 is a cross-sectional view of a single-cylinder shock absorber according to a first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of an essential part showing an outline of an orifice of the single-cylinder shock absorber, and FIG. The piston orifice (b) shows a reservoir orifice. The single-cylinder 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. As shown in FIGS. 1 and 2, the single-cylinder shock absorber 1 includes a cylinder 3, a piston 5, a partition wall 7, and an accumulator 9.

  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. A piston 5 is disposed in the fluid chamber 23 via a piston rod 25 so as to be movable in the axial direction.

  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 fluid chamber and an extension side pressure chamber 41 as a second fluid chamber on both sides. The piston 5 is provided with a pair of piston body 43 and 45, a valve 47 and 49.

  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 formed symmetrically in the radial direction 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 69). 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 circumferential claw portion 77 directed inward in the radial direction is integrally formed at the axial end portion of the insertion tube portion 75. 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 valves 47 and 49 that open and close the piston flow paths 65 and 67 by the fluid pressure of oil on both sides in the axial direction. Since the valves 47 and 49 are symmetrically arranged in the opposite direction 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 47 (valve 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 47 (valve 49) includes a valve main body 79 and a spring 81 as an urging member.

  The valve body 79 is formed in a substantially truncated cone shape and has a tapered shape with a tapered outer peripheral surface. Therefore, the valve body 79 is a columnar body whose sectional area gradually decreases 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 body 79. The flange 83 is provided with a circular recess 85.

  The valve body 79 is disposed concentrically with the piston rod 25 and is inserted and supported so as to be axially movable. That is, the valve body 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 so as to be movable in the axial direction. The valve main body 79 moves in and out with respect to the insertion cylinder portion 75 by moving in the axial direction.

  That is, the valve body 79 is seated with its distal end inserted into the insertion tube portion 75 by axial movement (insertion movement) toward the piston 5. At the time of seating, the concave portion 85 of the flange 83 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 body 79 forms a gap corresponding to the drawing amount between the valve main body 79 and the claw portion 77 of the insertion cylinder portion 75. In this embodiment, based on the taper shape of the outer peripheral surface on the front end side of the valve body 79, the gap increases linearly as the amount of withdrawal of the valve body 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 body 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 body 79 in the insertion direction into the insertion cylinder portion 75.

  In the valve 47 (valve 49), the valve main body 79 is pulled out to 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 41). As a result, the valve 47 (valve 49) forms a piston orifice 89 (piston orifice 91) by the gap as shown in FIG.

  In the piston orifice 89 (piston orifice 91), the opening area with respect to the fluid pressure is set in accordance with the setting of the valve characteristic of the valve 47 (valve 49). In the present embodiment, as the valve characteristics, for example, the diameter of the valve body 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 flow path 67 (piston flow path 65), etc. are set. The

  As shown in FIG. 1, the partition wall portion 7 includes a wall body 93, a valve 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 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 95 is configured in the same manner as the valves 47 and 49 on the piston 5 side, and includes a valve main body 125 and a spring 127 as an urging member.

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

  The valve body 125 is inserted and supported on 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 main body 125 moves in and out with respect to the insertion tube portion 119.

  That is, the valve main body 125 is seated by the insertion movement to the insertion cylinder portion 119 and closes the reservoir flow path 115, like the valve main body 79 on the piston 5 side. In addition, the valve body 125 forms a gap corresponding to the amount of withdrawal between the valve body 125 and the claw part 121 of the insertion cylinder part 119 by the movement of withdrawal from the insertion cylinder part 119. In this embodiment, based on the tapered shape of the outer peripheral surface on the front end side of the valve body 125, the gap increases linearly as the amount of withdrawal of the valve body 125 increases.

  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 body 125. The spring 127 is inserted and supported on the outer periphery of the spacer 113 of the piston rod 25, and urges the valve body 125 in the insertion direction into the insertion tube portion 119.

  In such a valve 95, the valve main body 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 95 forms a reservoir orifice 135 by the gap.

  Similarly to the valve 47 on the piston 5 side, the opening area of the reservoir orifice 135 with respect to the fluid pressure is set by setting the valve characteristic of the valve 95. As the valve characteristics, for example, the diameter of the valve body 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 partitions the fluid chamber 23 and partitions the reservoir chamber 99 with the partition 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.
[Operation of single cylinder type shock absorber]
First, each operation of the valve 47 and the valve 95 and the operation of the single-cylinder shock absorber 1 by this will be described.

  In the single-cylinder shock absorber 1 of the present embodiment, a 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 47 of the piston 5 operates to generate a damper effect.

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

  A piston orifice 89 based on the tapered shape of the valve main body 79 is formed between the valve main body 79 and the inner peripheral edge of the claw portion 77 of the insertion cylinder portion 75 in accordance with the drawing amount. Therefore, in the single cylinder type shock absorber 1, oil is circulated from the contraction side pressure chamber 39 side to the expansion side pressure chamber 41 side via the piston orifice 89 to generate a damper effect corresponding to the opening area of the piston orifice 89. be able to.

  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 95 of the partition wall 7.

  That is, the valve main body 125 of the valve 95 receives the fluid pressure of oil from the contraction side pressure chamber 39 via the reservoir channel 115 and the insertion cylinder portion 119 according to the moving speed of the piston 5 like the valve 47 of the piston 5. .

  As a result, the valve main body 125 moves in the axial direction against the urging force of the spring 127, and a reservoir orifice 135 based on the tapered shape of the outer peripheral surface on the distal end side is formed between the valve main body 125 and the insertion tube portion 119 in accordance with the pulling amount. The

  Therefore, in the single cylinder shock absorber 1, excess oil can be circulated 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 41 side. In response to this movement, the other valve 49 of the piston 5 is operated, and the damper effect can be generated in the same manner as in the contracting 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 partition wall portion 7 opens and moves 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 valves 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 41 side and the reservoir chamber 99 side.

  Therefore, the valve main body 79 of the valve 47 opens the piston flow path 67 to form the piston orifice 89 as described above, and the valve main body 125 of the valve 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 41 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.

That is, 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. For this reason, 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 a 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 41. Further, when the flow velocity v is equal to the flow velocity V, the pressure in the extension side pressure chamber 41 can be made zero by the gauge pressure.
[Effect of Example 1]
The single-cylinder shock absorber 1 according to the present embodiment is movably disposed in a cylinder 3 filled with oil as a working fluid, and moves in a telescopic manner with respect to the cylinder 5. The piston 5 partitions the pressure chambers 39 and 41. A piston rod 25 for interlocking the piston 5, and at least the oil flows from the pressure chamber 39 to the pressure chamber 41 according to the movement of the piston 5 toward the pressure chamber 39 due to the contraction movement of the piston rod 25 provided on the piston 5. The piston orifice 89, the partition wall 7 that partitions the reservoir chamber 99 that can absorb the volume change due to the contraction movement of the piston rod 25 with respect to the pressure chamber 39, and the volume change caused by the movement of the piston rod 25 provided in the partition wall section 7. A reservoir orifice 135 through which a minute amount of oil flows from the pressure chamber 39 to the reservoir chamber 99. Area ratio of 135 and contraction side of the piston orifice 89 is set below the cross-sectional area ratio of the piston rod 25 and the piston 5.

  Therefore, in the single cylinder shock absorber 1, the pressure difference between the reservoir chamber 99 and the pressure chamber 39 is larger than the pressure difference between the pressure chambers 39 and 41 by setting the area ratio between the reservoir orifice 135 and the piston orifice 89. can do. For this reason, without using high pressure gas for the accumulator 9, the damper effect by expansion-contraction operation | movement can be produced | generated reliably, and it can suppress that an inside becomes a high voltage | pressure.

  As a result, the single-cylinder shock absorber 1 can suppress the occurrence 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 single cylinder type shock absorber.

  Moreover, since the single-cylinder 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, the heat dissipation is good, and the horizontal cylinder is used in the horizontal direction. You can also.

  Thus, in the single cylinder type shock absorber 1 of the present embodiment, the single cylinder type shock absorber characteristic similar to that of the double cylinder type can be obtained although it is a single cylinder type.

  Since the partition wall portion 7 includes the annular flow channel 117 that allows oil to freely flow from the reservoir chamber 99 to the pressure chamber 39, the pressure difference between the reservoir chamber 99 and the pressure chamber 39 is reduced as described above. , 41 can be made larger than the pressure difference, while the expansion and contraction and extension operations can be performed smoothly.

  In the single-cylinder shock absorber 1 of the present embodiment, the piston flow path 67 formed through the piston 5, the reservoir flow path 115 formed through the partition wall 7, the piston 5 and the partition wall 7 are provided, Valves 47 and 95 that open and close the piston flow path 67 and the reservoir flow path 115 according to the moving speed of the piston 5 to form the piston orifice 89 and the reservoir orifice 135, and the ratio between the reservoir orifice 135 and the piston orifice 89 is It is set according to the valve characteristics of the valves 47 and 95.

  Therefore, in the single cylinder type shock absorber 1 of the present embodiment, the ratio setting can be performed easily and reliably.

  The valves 47 and 95 are valve bodies 79 and 125 supported so as to be movable in and out in the axial direction with respect to the piston channel 67 and the reservoir channel 115, and the valve bodies 79 and 125 are connected to the piston channel 67 and the reservoir channel 115. And springs 81 and 127 as urging members for urging in the insertion direction.

  The valve bodies 79 and 125 close the piston flow path 67 and the reservoir flow path 115 by the biasing force of the springs 81 and 127, and resist the biasing force of the springs 81 and 127 by the pressure on the pressure chamber 39 side. The area of the piston orifice 89 and the reservoir orifice 135 can be changed by being drawn out from the passage 67 and the reservoir channel 115.

  That is, in the single-cylinder shock absorber 1 of the present embodiment, the moving speed of the piston 5 is set by setting a relative shape change between the valve main bodies 79 and 125 and the piston flow path 67 and the reservoir flow path 115 accompanying the drawing. Accordingly, the opening area of the piston orifice 89 and the reservoir orifice 135 can be set.

  As a result, the characteristics of the single cylinder shock absorber 1 can be set without being directly affected by the elastic characteristics of the valve bodies 79 and 125 and the springs 81 and 127.

  In particular, in the single-cylinder shock absorber 1 of this embodiment, even if the elastic characteristics of the springs 81 and 127 vary, it can be absorbed by the setting of the shape change, and the characteristics of the single-cylinder shock absorber 1 can be stabilized. Can be made.

  In the single cylinder shock absorber 1 of this embodiment, the single cylinder shock absorber characteristics can be freely set regardless of the elastic characteristics of the valve bodies 79 and 125 and the springs 81 and 127 by setting the shape change. Can do.

  Since the piston 5 and the partition wall portion 7 are provided on the valves 47 and 95 side with the insertion tube portions 75 and 119 for communicating with the piston flow path 67 and the reservoir flow path 115 and for inserting the valve main bodies 79 and 125, respectively. The valve main bodies 79 and 125 can be reliably moved in and out of the piston flow path 67 and the reservoir flow path 115 and set for the shape change.

  In the single cylinder type shock absorber 1 of this embodiment, the insertion cylinder parts 75 and 119 are provided with circular claw parts 77 and 121 at the ends thereof, and the claw parts of the insertion cylinder parts 75 and 119 are closed when the valve main bodies 79 and 125 are closed. Since the circular recesses 85 and 129 fitted to the portions 77 and 121 are provided, the stability in the closed state can be improved and the shape change can be set more easily and reliably.

  The valve bodies 79 and 125 are columnar bodies (conical frustum shape) that gradually decrease 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 according to the above.

Piston 5, Ri Contact with a valve 47 and 49 on both sides, a pair of piston channels 65, 67 which communicates within a circumferential insertion tube 75 opposite the valve from the insertion tube portion 75 the outer peripheral side of each valve Yes.

  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.

  Since the reservoir chamber 99 is provided in series with the contraction side pressure chamber 39 in the cylinder 3, the structure can be simplified.

  The single-cylinder shock absorber 1 is composed of a free piston 143 whose back side is open to the atmosphere on the back side of the accumulator 9, so that the structure change can be simplified and the volume change in the fluid chamber 23 can be absorbed 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 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. is there. 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 body 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 pull-out amount.

  The valve main body 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 drawing amount.

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

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

  Also in this embodiment, the same effects as those of the first embodiment can be obtained.

  Embodiment 3 of the present invention will be described below with reference to FIG. FIG. 6 is an enlarged cross-sectional view of a main part of a single cylinder shock absorber according to a third embodiment of the present invention. Note that the basic configuration of the present embodiment is the same as that of the first embodiment, and the corresponding components are denoted by the same reference numerals or the same reference numerals with Ds and detailed description thereof is omitted.

  A single-cylinder shock absorber 1D of FIG. 6 is provided with an accumulator 9D made of an independent foam rubber as an independent foam elastic body, instead of the accumulator 9 provided with the free piston 143 of the above embodiment.

  In the single cylinder shock absorber 1D, the cap 21 of the cylinder 3D is omitted, and an end wall portion 155 integrated with the end cylinder portion 7D is provided. A reservoir chamber 99D is defined by the partition wall 7 in the end cylinder portion 7D. An accumulator 9D is accommodated in the reservoir chamber 99D.

  In such a single-cylinder shock absorber 1D, the accumulator 9D expands and contracts due to the oil flowing into and out of the reservoir chamber 99, and the volume change in the fluid chamber 23D can be absorbed.

  Also in the single cylinder type shock absorber 1D of the present embodiment, the same operational effects as those of the above embodiment can be obtained.

  Embodiment 4 of the present invention will be described below with reference to FIG. FIG. 7 is a cross-sectional view of a single cylinder type shock absorber according to a fourth embodiment of the present invention. The basic configuration of the present embodiment is the same as that of the first embodiment, and the corresponding components are denoted by the same reference numerals or the same reference numerals with E added thereto, and detailed description thereof is omitted.

  A single cylinder type shock absorber 1E of FIG. 4 is replaced with a reservoir chamber 99E and an accumulator 9E in a reservoir tank 157 separate from the cylinder 3E, instead of the reservoir chamber 99 and the accumulator 9 provided in the cylinder 3 of the above embodiment. Is provided.

  The reservoir tank 157 is formed in a cylindrical shape and is provided side by side with the cylinder 3E. One end side of the reservoir tank 157 is connected to the cylinder 3E through a communication pipe 159.

  In the reservoir tank 157, a partition wall 7 is provided on the other end side with respect to the communication pipe 159. A reservoir chamber 99E is partitioned by the partition wall 7 on the other end side of the reservoir tank 157. An actuator 9E including a free piston 143E and a back space 145E is provided in the reservoir chamber 99E.

  In such a single cylinder type shock absorber 1E, oil flowing between the cylinder 3E side and the reservoir tank 157 enters and exits the reservoir chamber 99E, thereby operating the accumulator 9E to absorb the volume change in the fluid chamber 23E. can do.

  Also in the single cylinder type shock absorber 1E of the present embodiment, the same operational effects as those of the above embodiment can be obtained.

  Embodiment 5 of the present invention will be described below with reference to FIGS. FIG. 8 is an enlarged cross-sectional view of a main part of a single cylinder shock absorber according to a fifth embodiment of the present invention, and FIG. 9 is an enlarged cross-sectional view of the main part according to the modification. The basic configuration of the present embodiment is the same as that of the first or fourth embodiment, and corresponding components are denoted by the same reference numerals or the same reference numerals with F or G, and detailed description thereof is omitted.

  In the single-cylinder shock absorbers 1F and 1G of FIGS. 8 and 9, low pressure gas is sealed in the back spaces 145F and 145G in place of the return spring 149 provided in the back space 145 of the accumulator 9 as in the above embodiment. Is.

  In the single cylinder shock absorber 1F of FIG. 8, the through hole 31 of the cap 21F of the cylinder 3F is omitted. Thereby, the back space 145F is closed between the cap 21F and the free piston 143F of the accumulator 9F.

  In this back space 145F, for example, a low pressure gas of 2 atm or less is sealed. The low pressure gas can urge the free piston 143F of the accumulator 9F in the same manner as the spring 149.

  On the other hand, in the single cylinder shock absorber 1G of FIG. 9, the end of the reservoir tank 157G of the cylinder 3G is closed by the end wall 155G. As a result, the back space 145G is closed between the end wall portion 155G and the free piston 143G of the accumulator 9G, and low pressure gas is sealed in the back space 145G in the same manner as described above.

  Therefore, also in the single cylinder type shock absorbers 1F and 1G of the present embodiment, the same operational effects as those of the above embodiment can be obtained.

  Embodiment 6 of the present invention will be described below with reference to FIG. FIG. 10 is a schematic sectional view showing a single-cylinder shock absorber according to a sixth embodiment of the present invention. Note that the basic configuration of the present embodiment is the same as that of the first embodiment, and the corresponding components are denoted by the same reference numerals or the same reference numerals, and detailed description thereof is omitted.

  The single-cylinder shock absorber 1H of the present embodiment is obtained by omitting the valves 47, 49, and 95 of the above-described embodiment.

  That is, the piston office 159 is composed of a piston flow path 161 formed through the piston 5H. The piston orifice 159 circulates oil in both expansion and contraction operations.

  The reservoir orifice 135H is composed of a reservoir channel 115H formed through the partition wall portion 7H. In this embodiment, a check valve 97E is used instead of the relief valve.

  In the single cylinder shock absorber 1H, the ratio between the reservoir orifice 115H and the piston orifice 159 is set in the same manner as in the above embodiment by setting the cross-sectional areas of the reservoir orifice 115H and the piston orifice 159.

Therefore, also in the present embodiment, the same operational effects as those of the above embodiment can be obtained. In addition, in the single cylinder shock absorber 1H of the present embodiment, the structure can be simplified.
[Others]
As mentioned above, although the Example of this invention was described, this invention is not limited to this, Various design changes are possible.

  The configuration of the valve can be set freely. For example, a valve made of a disc spring can be used in place of the valves 47, 49, and 95.

  In the above-described embodiment, the gap with the flow path is set by setting the shapes of the valves 47, 49, and 95. Conversely, the gap can be set by setting the shape of the flow path.

  As the urging members of the valves 47 and 49.95, it is sufficient that the valve main bodies 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 49 of the piston 5.

DESCRIPTION OF SYMBOLS 1 Single cylinder type shock absorber 3 Cylinder 5 Piston 7 Bulkhead part 9 Accumulator 39, 41 Pressure chamber (1st fluid chamber and 2nd fluid chamber)
43, 45 Piston body 47, 49, 125 Valve 65, 67 Piston flow path 75 Insertion cylinder part 77, 121 Claw part 79 Valve body 81, 127 Spring (biasing member)
85,129 Recessed portion 89,91 Piston orifice 95 Valve 99 Reservoir chamber 115 Reservoir flow path 143 Free piston

Claims (13)

A piston that is movably disposed in a cylinder filled with a working fluid and that defines a first fluid chamber and a second fluid chamber on both sides;
A piston rod that expands and contracts in the cylinder and interlocks the piston;
A piston orifice that is provided in the piston and circulates the working fluid from the first fluid chamber to the second fluid chamber in response to movement of the piston toward the first fluid chamber due to contraction movement of the piston rod;
A partition wall partitioning a reservoir chamber capable of absorbing a volume change due to contraction movement of the piston rod with respect to the first fluid chamber;
A reservoir orifice that is provided in the partition wall and circulates the working fluid corresponding to the volume change from the first fluid chamber to the reservoir chamber;
The area ratio of the reservoir orifice and the piston orifice was set to be equal to or less than the sectional area ratio of the piston rod and the piston,
Single cylinder shock absorber. A single-cylinder shock absorber according to claim 1,
The partition portion includes an annular flow path that allows the working fluid to freely flow from the reservoir chamber to the first fluid chamber.
Single cylinder shock absorber. A single-cylinder shock absorber according to claim 1 or 2,
A piston passage formed through the piston;
A reservoir channel formed through the partition wall;
A valve provided separately for each of the piston and the partition, and opening and closing the piston channel and the reservoir channel according to the moving speed of the piston to form the piston orifice and the reservoir orifice;
The ratio between the reservoir orifice and the piston orifice is set by the valve characteristics of the valve,
Single cylinder shock absorber. A single-cylinder shock absorber according to claim 3,
Each of the valves includes a valve main body that is supported so as to be movable in and out in the axial direction with respect to the piston flow path or the reservoir flow path, and a bias that biases the valve main body in the insertion direction with respect to the piston flow path or the reservoir flow path With members,
The valve body closes the piston flow path or the reservoir flow path by a biasing force of the biasing member and resists the biasing force of the biasing member by the pressure on the first fluid chamber side. Or pulled out of the reservoir flow path to change the area of the piston orifice or reservoir orifice,
Single cylinder shock absorber. A single-cylinder shock absorber according to claim 4 ,
The valve body is a columnar body that gradually decreases in cross-sectional area from the front end side in the pull-out direction toward the rear end side.
Single cylinder shock absorber. A single-cylinder shock absorber according to claim 4 or 5 ,
Each of the valves includes an insertion cylinder portion that is provided in the piston or the partition wall portion and communicates with the piston flow path or the reservoir flow path and inserts the valve main body.
Single cylinder shock absorber. A single-cylinder shock absorber according to claim 6 ,
The insertion tube portion includes a circular claw at its end,
The valve body includes a circular recess that fits into the claw portion of the insertion tube portion in the closed state.
Single cylinder shock absorber. A single-cylinder shock absorber according to claim 6 or 7 ,
Said piston, said comprises the valve on both sides of the first fluid chamber and second fluid chamber, a pair of pistons which communicates from the outer side of one of the insertion tube of the valves on the inner peripheral side of the other of the insertion tube portion With a flow path,
Single cylinder shock absorber. A single-cylinder shock absorber according to claim 1,
The piston orifice consists of a piston flow path formed through the piston,
The reservoir orifice consists of a reservoir channel formed through the partition wall,
The ratio is set by setting the cross-sectional areas of the reservoir orifice and the piston orifice.
Single cylinder shock absorber. A single-cylinder shock absorber according to any one of claims 1 to 9,
The reservoir chamber is provided in series with the first fluid chamber in the cylinder.
Single cylinder shock absorber. A single-cylinder shock absorber according to any one of claims 1 to 9,
The reservoir chamber is provided in a reservoir tank separate from the cylinder.
Single cylinder shock absorber. A single-cylinder shock absorber according to any one of claims 1 to 11,
The reservoir chamber is open to the atmosphere on the back side or provided with a low pressure free piston.
Single cylinder shock absorber. A single-cylinder shock absorber according to any one of claims 1 to 11,
The reservoir chamber includes an independent foamed elastic body,
Single cylinder shock absorber.