JP2008303927A - piston - Google Patents

Abstract

A damping force in a low speed region can be proportional to a piston speed.
SOLUTION: Two discs 10 and 20 are laminated, and one side disc 10 has one side outlet hole 13 communicating with a mating surface 11a with the other side disc 20 and the opposite side surface 12, and an opposite side surface 12. One side inlet hole 14 that opens from the outer peripheral side to the one side outlet hole 13 and communicates with the mating surface 11a, and the other side disk 20 communicates the mating surface 21 with the one side disk 10 and the opposite side surface 22 Side outlet hole 23 and the other side inlet hole 24 that opens from the outer peripheral side of the opposite side surface 22 and communicates with the mating surface 21. One side outlet hole 13 and the other side inlet hole 24 The port P1 is formed, the other side outlet hole 23 and the one side inlet hole 14 form the other port P2, and one port is provided on one or both of the mating surface 11a of the one side disk 10 and the mating surface 21 of the other side disk 20. P1 and other port And 2 provided with a choke passage C communicating.
[Selection] Figure 2

Description

  The present invention relates to improvements in shock absorber pistons.

  Generally, a piston provided in a shock absorber functions as a valve disk of a damping valve. As a damping valve using a piston, a piston that separates two pressure chambers in the shock absorber, and a piston provided in the piston are provided. In addition, an annular leaf valve seated on an annular valve seat disposed on the outer periphery of the port is known, and this leaf valve is used to open and close the port.

  In the damping valve that opens and closes the port by bending the outer peripheral side of the leaf valve, when the piston speed is low, the working liquid is formed by a notch provided in the annular valve seat or a notch provided in the outer periphery of the leaf valve. Through the orifice to be moved from the pressure chamber to be compressed to the pressure chamber to be expanded.

  Therefore, in such a damping valve, when the piston speed is low, a damping characteristic (a change in damping force with respect to the piston speed) that is a square characteristic peculiar to the orifice is exhibited, and the piston speed when the piston speed is in a low speed region. The damping force changes greatly with respect to the change, and when the piston speed goes out of the low speed range and becomes medium speed, the leaf valve separates from the annular valve seat, so the damping characteristics in the medium speed range are significantly different from those in the low speed range. The attenuation characteristics change abruptly.

  Therefore, in order to change the damping force linearly with respect to the piston speed in the low speed region, the leaf valve seated on the valve seat and a part of the sub leaf valve stacked on the leaf valve are provided with a notch and stacked on the top. A damping valve has been proposed in which a choke passage is configured by closing most of the notch with a sub-leaf valve (see, for example, Patent Document 1).

In addition, there is another proposal in which a choke passage is formed in the piston rod in parallel with a port provided in the piston, and the damping force is linearly changed with respect to the piston speed in a low speed region (see, for example, Patent Document 2). ).
JP 2001-165224 A JP 2000-186734 A

  However, the damping force valve configured as described above may be pointed out to have the following problems, although there is no particular problem.

  That is, when the choke passage is formed by the leaf valve and the sub leaf valve, when the piston speed is very low, the hydraulic oil that has passed through the port generates a high damping force by passing through the choke passage. If the choke passage is not formed securely with the sub-leaf valve, the hydraulic oil leaks from the gap between the leaf valve and the sub-leaf valve, resulting in the desired damping characteristics when the piston speed is low. It may not be possible.

  In addition to manufacturing the leaf valve and sub-leaf valve with high processing accuracy, high assembly accuracy is required when laminating the leaf valve and sub-leaf valve.

  Therefore, there is a problem that the manufacturing cost of the leaf valve itself and the assembling cost for stacking the leaf valves increase, and the manufacturing cost of the shock absorber itself increases.

  In addition, when the choke passage is formed in the piston rod, a stable damping characteristic can be generated regardless of the laminated state of the leaf valve and the sub leaf valve, but the piston rod needs to be perforated. It is necessary to attach a plug provided with a choke passage to the hole provided in the piston rod, which is troublesome and increases the manufacturing cost.

  Therefore, the present invention was devised in order to improve the above-described problems, and the object of the present invention is to provide a damping force in a low speed region when processed easily and inexpensively and applied to a shock absorber. Is to provide a piston that can be changed in proportion to the piston speed.

  In order to solve the above-described object, the problem-solving means in the present invention is a piston connected to a piston rod of a shock absorber, which is formed by stacking two disks, and one side disk is connected to the other side disk. One side outlet hole that communicates with the mating surface and the opposite side surface, and one side inlet hole that opens from the outer peripheral side than the one side outlet hole on the opposite side surface and communicates with the mating surface. The other side outlet hole that communicates with the mating surface and the opposite side surface, and the other side inlet hole that opens from the outer peripheral side than the other side outlet hole on the opposite side surface and communicates with the mating surface. One port is formed by the hole, the other port is formed by the other side outlet hole and the one side inlet hole, and one port and the other port are formed on one or both of the mating surface of the one side disc and the mating surface of the other side disc. A choke passage was established to communicate

  According to the piston of the present invention, when the damping force in the low speed region is changed in proportion to the piston speed, one port and the other port are formed on the mating surface of the one side disk and the other side disk that can be manufactured by sintering. As a result, a choke passage that communicates with each other is formed, so that the processing of the choke passage is easy and the manufacturing cost is reduced.

  Moreover, if this piston is applied to a shock absorber, the choke passage functions stably regardless of the laminated state of the leaf valve, so that the damping force in the low speed region is reliably proportional to the piston speed. It can be changed, and stable damping force can be expected.

  Hereinafter, the piston of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a piston in one embodiment. FIG. 2 is a YY ′ cross-sectional view of the piston according to the embodiment. FIG. 3 is a perspective view of one side disk constituting the piston in one embodiment. FIG. 4 is a perspective view of the other-side disk constituting the piston in the embodiment. FIG. 5 is a diagram illustrating a damping characteristic of a shock absorber to which a piston according to one embodiment is applied.

  As shown in FIGS. 1 to 4, the piston 1 in one embodiment is fixed to the tip of the piston rod 2 of the shock absorber, and the two disks of the one side disk 10 and the other side disk 20 are stacked. The cylinder 40 is slidably inserted into the cylinder 40 constituting the shock absorber, and the cylinder 40 is partitioned into an upper chamber 41 and a lower chamber 42.

  As will be described in detail later, the piston 1 is formed by one port P1 formed by the one side outlet hole 13 and the other side inlet hole 24, and the other side outlet hole 23 and one side inlet hole 14. The other port P2 is provided to communicate the upper chamber 41 and the lower chamber 42 of the shock absorber.

  A leaf valve 4 that is seated on the valve seat 15 and opens and closes the one-side outlet hole 13 is stacked below the one-side disk 10 in FIG. 2, and the other-side disk 20 is positioned above the one in FIG. The leaf valve 5 that is seated on the valve seat 25 and opens and closes the other side outlet hole 23 is laminated, and the piston 1 has the other end disk 20 disposed at the upper end in FIG. It is fixed with.

  On the other hand, a shock absorber to which the piston 1 is applied is well known and will not be described in detail, but specifically, for example, a cylinder 40 and a head member (not shown) that seals the upper end of the cylinder 40. ), A piston rod 2 slidably passing through a head member (not shown), the piston 1 provided at the tip 2a of the piston rod 2, and two pressures separated by the piston 1 in the cylinder 40 The upper chamber 41 and the lower chamber 42, which are chambers, a sealing member (not shown) for sealing the lower end of the cylinder 40, and a cylinder internal volume change corresponding to the volume of the piston rod 2 protruding and retracting from the cylinder 40 are not shown. The cylinder 40 is filled with a fluid, specifically, hydraulic oil.

  Therefore, in the case of this shock absorber, when the piston 1 moves upward in FIG. 1 with respect to the cylinder 40, the pressure in the upper chamber 41 rises and the leaf valve 4 seated on the valve seat 15 of the one side disk 10 is Since the one side outlet hole 13 is bent downward in FIG. 2, the hydraulic oil is formed by the other side inlet hole 24 of the other side disk 20 and the one side outlet hole 13 of the one side disk 10. One port P1 moves from the upper chamber 41 to the lower chamber 42 through the port P1, and the other port P1 functions as an expansion side port through which hydraulic oil passes when the shock absorber extends, and the leaf valve 4 A resistance is applied to the flow of the hydraulic oil passing through the expansion side port to cause a predetermined pressure loss, and a predetermined expansion side damping force is generated in the shock absorber. On the other hand, when the piston 1 moves downward in FIG. 2 with respect to the cylinder 40, the pressure in the lower chamber 42 rises and the leaf valve 5 seated on the valve seat 25 of the other disk 20 is bent upward in FIG. Since the other side outlet hole 23 is opened, the hydraulic oil passes through the other port P2 formed by the one side inlet hole 14 of the one side disk 10 and the other side outlet hole 23 of the other side disk 20. The other port P2 functions as a pressure side port through which hydraulic oil passes when the shock absorber is compressed, and the hydraulic oil passes through the pressure side port with the leaf valve 5. Thus, a predetermined pressure loss is generated by applying resistance to the flow of the pressure, and a predetermined compression side damping force is generated in the shock absorber.

  Hereinafter, each part of the above-described piston 1 will be described in detail. The one side disk 10 constituting the piston 1 is manufactured by sintering and is formed into a bottomed cylindrical shape having a concave portion 11, and a piston rod is inserted into the center portion. A plurality of one-side outlet holes 13 provided with a hole 10a and communicating with a bottom surface 11a of the concave portion 11 disposed on the same circumference and serving as a mating surface with the other side disk 20 and a bottom surface 12 serving as the opposite side surface; A plurality of one-side inlet holes 14 that open from the outer peripheral side to the one-side outlet holes 13 and communicate with the one-side outlet holes 13 of the bottom surface 11a of the recess 11 are provided.

  The one-side outlet holes 13 are provided at regular intervals in the illustrated manner, and the outlet ends of the one-side outlet holes 13 are communicated by an annular window 16 provided on the lower surface 12 of the one-side disk 10, An annular valve seat 15 on which the leaf valve 4 is attached and detached is provided on the outer periphery of the annular window 16. Further, the opening end on the upper side of the one-side outlet hole 13 is on the same circumference as the bottom portion 11a of the recess 11, and at a position avoiding the edge of the bottom portion 11a, that is, the boundary between the bottom portion 11a and the side wall portion 11b. Has been placed.

  The one side inlet holes 14 are provided at regular intervals in the illustrated manner, and are opened from the outer peripheral side of the valve seat 15 and communicated with the bottom 11a of the recess 11, but the opening end on the bottom 11a side is While arrange | positioned between the one side exit holes 13 and 13, this is also arrange | positioned in the position which avoids the edge of the bottom part 11a, ie, the boundary of the bottom part 11a, and the side wall part 11b.

  Subsequently, the other-side disk 20 is manufactured by sintering and is a disk having a diameter that fits into the recess 11 of the one-side disk 10, and has a piston rod insertion hole 27 in the center, When the lower surface 21 in FIG. 2 is fitted until it contacts the bottom 11 a of the recess 11, the vertical length is set so that the upper portion protrudes from the recess 11. In this way, the other side disk 20 is inserted in the concave part 11 of the one side disk 10 by inserting the lower end side in FIG. It is designed to be positioned.

  And the other side disk 20 which comprises the piston 1 is arrange | positioned on the same periphery, and the several other side exit hole which connects the lower surface 21 used as the mating surface with the one side disk 10, and the upper surface 22 used as an opposite side surface 23 and a plurality of other inlet holes 24 that open from the outer peripheral side wall surface 20a of the other disk 20 that is on the outer peripheral side from the other outlet hole 23 of the upper surface 22 and communicate between the other outlet holes 23, 23 of the lower surface 21. It is configured with.

  The other-side outlet holes 23 are provided at equal intervals in the figure, and the outlet ends of the other-side outlet holes 23 are communicated with an annular window 26 provided on the upper surface 22 of the other-side disk 20. An annular valve seat 25 on which the leaf valve 5 is attached and detached is provided on the outer periphery of the annular window 26. The opening end on the lower side of the other side outlet hole 23 is arranged on the same circumference as the lower surface 21 and at a position avoiding the edge of the lower surface 21, that is, the boundary between the lower surface 21 and the outer peripheral side wall surface 20a. ing.

  The other side inlet holes 24 are provided at equal intervals in the figure and open from the outer peripheral side to the valve seat 25 and communicate with the lower surface 21, but the lower surface 21 side end is the other side outlet hole 23. , 23 and is open so as to cover the edge of the lower surface 21.

  That is, in the case of this embodiment, the other side inlet hole 24 is a notch provided from the outer peripheral side wall surface of the other side disk 20 to the lower surface 21 when viewed from the other side disk 20 alone. By fitting the disc 20 into the concave portion 11 of the one-side disc 10 as described above, the other side inlet hole 24 is formed by the inner wall surface of the concave portion 11 and the notch, and the other side inlet hole 24 has a concave portion. 11, the outer side wall surface 20 a of the other side disk 20 is opened from a portion projecting from the recess 11 so that the other side disk 20 is not blocked.

  When the other side disk 20 is fitted into the recess 11 of the one side disk 10, the other side inlet hole 24 of the other side disk 20 communicates with the one side outlet hole 13 of the one side disk 10, and the other side disk 20. The other-side outlet hole 23 and the one-side inlet hole 14 of the one-side disk 10 communicate with each other, and six one-ports P1 and six other-ports P2 are formed in the circumferential direction. When the other side disk 20 is fitted into the recess 11 of the one side disk 10, the communication between the other side inlet hole 24 and the one side outlet hole 13, and the other side outlet hole 23 and the one side inlet hole 14 are connected. In order to ensure communication, an appropriate positioning mechanism in the circumferential direction between the one side disk 10 and the other side disk 20 such as a pin, a key and a key groove, a protrusion and a recess, or a spline may be provided.

  Further, the other side disk 20 is provided on the same circumference and has a taper surface 21 a on the outer periphery of the end on the lower surface 21 side which becomes a mating surface with the one side disk 10, and is tapered from the other side outlet hole 23. A groove 21b communicating with the surface 21a is provided, and when the other side disk 20 is fitted into the recess 11 of the one side disk 10, a gap having a triangular cross section is formed between the tapered surface 21a and the inner wall of the recess 11, The annular gap and the groove 21b form a choke passage C that connects the other side inlet hole 24 and the other side outlet hole 23 of the other side disk 20 to each other. And the other port P2.

  The one-side disk 10 and the other-side disk 20 constituting each part of the piston 1 are configured as described above. In the piston 1, as described above, the one port P1 that functions as the expansion side port and the compression side Since the other port P2 functioning as a port is in communication with the choke passage C, the piston speed until the leaf valve 4 (5) bends from the valve seat 15 (25) to open the port P1 (P2). Is in the low speed region, the hydraulic oil moves back and forth between the upper chamber 41 and the lower chamber 42 via the choke passage C, so that the damping force generated by the buffer changes in proportion to the piston speed. .

  Further, when the piston speed at which the leaf valve 4 (5) is bent from the valve seat 15 (25) to open the port P1 (P2) is in the middle speed region, the leaf valve 4 (5) is connected to the port P1 (P2). When the piston speed is in the low speed region, the damping coefficient is low.

  Therefore, the damping characteristic of the shock absorber to which the piston 1 is applied is as shown in FIG. 5, and compared with the shock absorber using the damping valve having the orifice characteristic, at the boundary between the low speed region and the medium speed region. The damping characteristic does not change suddenly, and by applying this piston 1 to the shock absorber, the damping force in the low speed region can be changed in proportion to the piston speed.

  Further, the present invention does not employ a method for processing a leaf valve, a sub-leaf valve or a piston rod as in the conventional damping valve, and changes the damping force in the low speed region in proportion to the piston speed. In the piston 1, the choke passage C which connects the one port P1 and the other port P2 is formed on the mating surface of the one side disc 10 and the other side disc 20 which can be manufactured by sintering. Is easy and the manufacturing cost is reduced.

  Further, since the choke passage C functions stably regardless of the laminated state of the leaf valves, the damping force in the low speed region can be reliably changed in proportion to the piston speed, and stable damping can be achieved. The generation of power can be expected.

  Furthermore, since the choke passage C is formed in the piston 1 as compared with the case where the choke passage is formed by the leaf valve and the sub leaf valve as in the conventional damping valve, the sub leaf valve for forming the choke passage is unnecessary. Thus, the number of parts is reduced.

  In the embodiment, the mating surface of the one-side disk 10 and the other-side disk 20 is the bottom 11a and the side wall 11b of the recess 11 in the one-side disk 10 and the other-side disk 20 Is the lower side of the lower surface 21 and the outer peripheral side wall surface 20a, and when the opening end on the concave portion 11 side of the one side inlet hole 14 is opened to reach the boundary between the bottom portion 11a and the side wall portion 11b, the other side disk 20 Even if the groove 21b is not provided, the taper surface 21a forms the choke passage C that allows the other side inlet hole 24 of the other side disk 20 and the one side inlet hole 14 of the one side disk 10 to communicate with each other. In addition, when the opening end of the one-side inlet hole 14 on the concave portion 11 side opens to the side wall portion 11b of the concave portion 11, the outer peripheral side wall surface 20a and the concave portion 1 of the other-side disk 20 are opened. The the other side inlet hole 24 is provided a groove which functions as a choke passage to one or both of the side wall portion 11b and one side inlet aperture 14 may be in communication with the. That is, by forming the piston 1 in a two-part disk and forming a choke passage on the mating surface, the choke passage can be easily processed, the manufacturing cost is reduced, and stable damping force can be expected.

  Therefore, in addition to the above, instead of providing the tapered surface 21a, a groove may be provided at the edge of the recess 11 to form a choke passage in the groove.

  However, as in the present embodiment, a tapered surface 21a is provided on the outer periphery of the lower surface side which is the mating surface of the other disk 20, and the choke path is formed between the tapered surface 21a and the inner surface of the recess 11. When C is formed, it is possible to form the tapered surface 21a by sintering, which eliminates the need for post-processing for providing the choke passage C, and is further advantageous in that the manufacturing cost is further reduced.

  Although the choke passage C is annular in the above description, the choke passage C is not necessarily annular. However, in this embodiment, the choke passage C is formed by the tapered surface 21a and is annular, and Since the other side outlet hole 23 and the other side inlet hole 24 are connected to each other, even if a slight positional deviation with respect to the one side disk 10 occurs, the choke path length becomes uniform, which is generated. This is advantageous because the damping force does not vary. Similarly, when an annular choke passage is provided in the one-side disc 10, the above-mentioned advantages can be enjoyed if the one-side outlet hole 13 and the one-side inlet hole 14 communicate with each other through the choke passage.

  In addition, in the above description, the choke passage C is formed by the tapered surface 21a. Instead, the choke passage C is the lower surface 21 of the other-side disk 20, and the piston rod insertion hole 27, the other-side outlet hole 23, and the other-side side. A groove communicating with the other side outlet hole 23 and the other side inlet hole 24 may be provided between the inner edge of the inlet hole 24 and the groove may function as a choke passage. In this case, the other side outlet hole 23 and the other side inlet hole 24 communicating with each other through the groove can be arbitrarily selected from a plurality, so that the length of the choke passage can be changed by setting the length of the groove. .

  In addition, when the other side inlet hole is not formed by cutting out from the outer periphery of the other side disk 20 but is formed by a hole penetrating the upper side and the lower side of the other side disk 20, it is formed on the outer periphery of the lower end of FIG. Even if the taper surface 21a is formed, the choke passage C does not directly communicate with the other inlet hole formed by the hole, so that a groove similar to the groove 21b that communicates the other outlet hole 23 and the choke passage C is provided. Thus, any one of the plurality of other inlet holes can be selected and communicated with the choke passage C. In this case, the length of the choke passage C can be adjusted by arbitrarily selecting the other-side inlet hole formed by the other-side outlet hole 23 and the hole communicated with the choke passage C from a plurality of them. it can.

  Further, in the case of this embodiment, the concave portion 11 is provided in the one side disk 10 and the other side disk 20 is fitted and integrated to form the piston 1. However, the one side disk 10 and the other side disk 20 are simplified. As a disc shape, a choke passage may be formed on the laminated surface serving as the mating surface. However, the piston ring 7 provided on the outer periphery of the piston 1 can be mounted on the outer periphery of the one-side disk 10 by forming the one-side disk 10 in a bottomed cylindrical shape as in the present embodiment. When two simple disks are stacked and the piston ring 7 is attached to the outer periphery of the disk, it is possible to avoid a situation in which the outer peripheral surface of the piston ring 7 is uneven, and there is no risk of giving resistance to the expansion and contraction of the shock absorber. There exists an advantage of forming the one side disk 10 in a bottomed cylinder shape at a point.

  In the present embodiment, a plurality of one-side outlet holes 13, one-side inlet holes 14, the other-side outlet holes 23, and the other-side inlet holes 24 are provided, but the number thereof is arbitrary.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is not limited to the details shown or described.

It is a top view of the piston in one embodiment. It is YY 'sectional drawing of the piston in one Embodiment. It is a perspective view of the one side disk which comprises the piston in one Embodiment. It is a perspective view of the other side disk which comprises the piston in one Embodiment. It is a figure which shows the damping characteristic of the buffer which applied the piston in one Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 2 Piston rod 2a Piston rod tip 4, 5 Leaf valve 6 Piston nut 7 Piston ring 10 One side disk 10a, 27 Piston rod insertion hole 11 Recess 11a Bottom part 11b in concave part Side wall part 12 in concave part Lower face 13 One side outlet hole 14 One side inlet holes 15 and 25 Valve seats 16 and 26 Annular window 20 Other side disk 20a Outer peripheral side wall surface 21 Lower surface 21a Tapered surface 21b Groove 22 Upper surface 23 Other side outlet hole 24 Other side inlet hole 40 Cylinder 41 Upper chamber 42 Lower chamber C Choke passage P1 One port P2 The other port

Claims (5)

A piston connected to the piston rod of the shock absorber, which consists of two discs stacked,
The one-side disk includes a one-side outlet hole that communicates the mating surface with the other-side disk and the opposite side surface, and a one-side inlet hole that opens from the outer peripheral side of the one-side outlet hole on the opposite side surface and communicates with the mating surface. ,
The other side disk includes an other side outlet hole that communicates the mating surface with the one side disk and the opposite side surface, and an other side inlet hole that opens from the outer peripheral side to the mating surface from the other side outlet hole of the opposite side surface. ,
One port is formed by the one side outlet hole and the other side inlet hole, and the other port is formed by the other side outlet hole and one side inlet hole,
A piston characterized in that a choke passage for communicating one port and the other port is provided in one or both of the mating surface of the one side disk and the mating surface of the other side disc. The piston according to claim 1, wherein a concave portion is provided in the one side disk, and the other side disk is fitted into the concave portion of the one side disk. 3. The piston according to claim 2, wherein a taper portion is provided on the outer periphery of the mating surface side end portion of the other side disk, and a choke passage is formed in a gap formed between the inner wall of the concave portion of the one side disk and the taper portion. The piston according to any one of claims 1 to 3, wherein the choke passage is annular and is provided in the one side disk so as to communicate the one side outlet hole and the one side inlet hole. The piston according to any one of claims 1 to 3, wherein the choke passage is annular and is provided in the other side disk so as to communicate the other side outlet hole and the other side inlet hole.

Images