JP2009162306A - Shock absorber piston opening and closing valve plate by simple bending deformation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To handle a problem that damping force characteristics with respect to piston speed of a shock absorber comes out of proportional characteristics preferable in a region where piston speed is high to become too strong due to abrupt increase in deformation resistance of the seat to a valve opening with the increase of valve opening degree, in a shock absorber piston in which deformation for opening each valve of a discoid sheet member is not simple bending deformation but three-dimensional deformation requiring local expansion along a seat surface when three or more pressure sensitive relief valves are arranged around a center axial line of a piston and a valve plate is utilized as a disk-like elastic sheet member. <P>SOLUTION: A shock absorber piston is a discoid elastic seat which forces valve plates seating on valve seats to align the center with a center axial line of a piston and is fixed onto the valve seat in the center part, wherein only a pair of valve seats is arranged symmetrically to each other against the center axial line. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shock absorber piston incorporated in a vehicle wheel suspension device or the like.

  A shock absorber incorporated in a vehicle wheel suspension device, etc. is a cylinder that combines a cylinder and a piston and expands and contracts while absorbing an impact force when the piston slides in the cylinder across the fluid layer filled in the cylinder. -Although it is a piston device, the resistance force acting on the object moving in the fluid layer rapidly rises two-dimensionally with the increase of the moving speed, so the increase of the resistance force against the increase of the expansion / contraction speed is moderate. In general, the piston is provided with a pressure-sensitive relief valve that increases the opening as the differential pressure acting on both sides of the piston increases.

Since the piston rod is attached to the shock absorber piston along its central axis, the portion of the piston in which the pressure-sensitive relief valve can be incorporated is an annular portion around the piston lot attachment portion. Incorporation of a pressure-sensitive relief valve into such an annular portion has conventionally been achieved by placing three to four pressure-sensitive relief valves around the central axis of the piston in accordance with common sense regarding stability when a plurality of objects are arranged around the center point. It is carried out in a manner that is evenly spaced. Shock absorbers incorporated in vehicle wheel suspensions and the like are usually designed to act in both directions of expansion and contraction. If 3 to 4 pressure-sensitive relief valves are provided in each of the extension direction and the contraction direction, Six to eight pressure-sensitive relief valves are incorporated in the annular portion around the central axis, and they are usually arranged so that the pressure-sensitive relief valves in the extension direction and the pressure-sensitive relief valves in the contraction direction are alternately positioned. The For example, Patent Document 1 below shows an example in which four pressure-sensitive relief valves in the extending direction and four pressure-sensitive relief valves in the contracting direction are alternately arranged. Shows an example in which three pressure-sensitive relief valves in the extension direction and three pressure-sensitive relief valves in the contraction direction are alternately arranged instead of such an example of the arrangement of four each. .
JP-A-9-89032 JP-A-11-166574

  If 3-4 or more pressure-sensitive relief valves are annularly arranged around the central axis of the piston as described above, the valve plate for opening and closing these valves is located at the piston rod mounting part in the center. If each of the protrusions is configured as a star-shaped elastic sheet having an annular portion that is held in an overlapping manner, and a protrusion that extends toward the valve seat of each pressure relief valve, Each part can open and close the valve seat of each pressure relief valve by bending the base part while being held by the central annular part. However, if the valve plate is configured as such a star-shaped seat member, as long as no detent means such as a key that reliably prevents relative rotation between the star-shaped seat member and the piston body is provided. As the time elapses, rotation of the star seat member relative to the valve seat may occur, and the valve seat may remain open.

  Conventionally, three to four pressure-sensitive relief valves have been used because of the above-mentioned problem of deviation and the advantage that the valve plate can be easily assembled without questioning the rotational position of the valve plate with respect to the valve seat. The valve plate in the shock absorber piston arranged in an annular shape is formed as a disc-shaped seat member, and the overlapping portion on each valve seat at the peripheral portion acts as a valve plate for each valve. .

  However, when the valve plate is formed as such a disc-shaped sheet member, all the valves are opened and closed at the same time. For example, the case where four pressure-sensitive relief valves are provided is shown in FIG. As shown, the deformation of opening each valve of the disk-shaped sheet member is not a simple bending of the sheet, but is a three-dimensional deformation that requires local expansion and contraction of the elastic sheet along the sheet surface. Therefore, as the valve opening degree increases, the deformation resistance of the seat against the valve opening increases sharply, and the damping force characteristic with respect to the piston speed of the shock absorber is shown in the attached FIG. There is a problem that it is too strong and deviates from a preferable proportional characteristic in a high region.

  The present invention uses a disk-like elastic seat member as a valve plate for a plurality of pressure-sensitive relief valves provided in a shock absorber piston in an annular manner around a central piston rod mounting portion. It is an object of the present invention to provide a shock absorber piston that can cope with the above-mentioned problems and can stably obtain desirable damping force characteristics over a wide piston speed range from low speed to high speed.

  In order to solve the above problems, the present invention comprises an annular valve seat and a valve plate seated on the annular valve seat, and when the differential pressure acting on the front and back of the valve plate is below a predetermined value, the valve plate is seated on the valve seat. When the differential pressure is greater than or equal to the predetermined value, the valve plate floats up from the valve seat and opens a port surrounded by the valve seat to the outside of the valve seat. A shock absorber piston having a pair of pressure relief valves that perform a damping function when the piston moves in the first direction along the central axis and has a damping function when the piston moves in the first direction. The pressure-sensing relief valve includes a pair of pressure-sensing relief valves, and the valve seats of the pair of pressure-sensing relief valves are arranged symmetrically with respect to the central axis of the piston. The seated valve plate is the center of the piston It proposes a shock absorber piston, characterized in that an elastic sheet fixed discoid on valve seat at the center to match the center line.

  The piston is a pair of pressure-sensitive relief valves that perform a damping function when the piston moves in the second direction opposite to the first direction along the central axis, and the piston moves in the second direction. The pressure relief valves that perform a damping function include a pair of pressure relief valves, and the valve seats of the pair of pressure relief valves are also arranged symmetrically with respect to the central axis of the piston, The valve plate seated on the pair of valve seats may also be a disc-shaped elastic sheet whose center coincides with the central axis of the piston and is fixed on the valve seat at the center.

  The pair of pressure-sensitive relief valves that perform a damping function when the piston moves in the first direction and the pair of pressure-sensitive relief valves that perform a damping function when the piston moves in the second direction are: They may be arranged alternately around the central axis.

  As described above, when the differential pressure acting on the front and back of the valve plate is equal to or less than a predetermined value, the valve plate is seated on the valve seat. In a shock absorber piston having a pressure-sensitive relief valve, the valve plate floats above the valve seat and opens a port surrounded by the valve seat to the outside of the valve seat when the predetermined value is exceeded. A pair of pressure sensitive relief valves that perform a damping function when the piston moves in the first direction along the central axis, and a pressure sensitive relief valve that performs the damping function when the piston moves in the first direction. Including a pair of pressure-sensitive relief valves, the valve seats of the pair of pressure-sensitive relief valves are arranged symmetrically with respect to the central axis of the piston, and a valve plate seated on the pair of valve seats Centering with the center axis If it is a disc-like elastic sheet fixed on the valve seat at the part, the deformation of the disc-like elastic sheet that opens and closes the valve is a simple bending deformation, and even in a region where the piston speed is high, the piston speed It is possible to stably maintain an increase in damping force with respect to an increase in a desirable proportional characteristic.

  The piston is a pair of pressure-sensitive relief valves that perform a damping function when the piston further moves along the central axis in the second direction opposite to the first direction, and the piston moves in the second direction. The pressure relief valves that perform a damping function include a pair of pressure relief valves, and the valve seats of the pair of pressure relief valves are also arranged symmetrically with respect to the central axis of the piston, If the valve plate seated on the pair of valve seats is also a disc-like elastic sheet whose center is aligned with the central axis of the piston and is fixed on the valve seat at the center, the shock absorber operates in both the expansion and contraction directions. The same effect can be obtained in the operation in the extending direction and contracting direction.

  Even if there are only two pressure-sensitive relief valves symmetrically with respect to the central axis of the piston, a pair of pressure-sensitive relief valves and pistons that perform a damping function when the piston moves in the first direction. If a pair of pressure relief valves that perform a damping function when moving are alternately arranged around the center axis of the piston, the fluid mixing in the cylinder of the shock absorber is sufficiently uniformed by the reciprocating motion of the piston. Thus, there is no occurrence of uneven temperature distribution in the fluid in the cylinder.

  Although illustrated as an embodiment later, a valve seat of a pressure-sensitive relief valve is disposed symmetrically with respect to the central axis of the piston and performs a damping function when the piston moves in the first or second direction. In the light of its function, it means that there is only one pair, and the area surrounded by one valve seat is partitioned by a partition wall that presents a contact surface against the valve plate in the same manner as the valve seat. A structure that simply presents two valve seats from the top is considered as one valve seat here.

  FIG. 1 attached herewith is a schematic sectional view showing a shock absorber piston according to the present invention in a state where it is incorporated in a shock absorber according to one embodiment, and FIG. It is the end view of the valve seat part of the piston which looked at the piston in the arrow direction by II. 1 corresponds to a longitudinal sectional view of the piston when the piston is viewed in the direction of the arrow along the cutting plane II in FIG.

  The piston 10 has a pair of pressure-sensitive relief valves 14 that allow fluid to escape upward from below the piston 12 as it moves downward in the figure relative to the cylinder 12, which is symmetrical with respect to the central axis of the piston. On the other hand, a pair of pressure-sensitive relief valves 16 are provided symmetrically with respect to the central axis of the piston for allowing fluid to escape downward from above the piston when moving upward in the figure. These pressure-sensitive relief valves 14 and 16 are pistons. Are alternately arranged around the central axis.

  Each of the pressure-sensitive relief valves 14 includes a port 18 penetrating the piston, an annular valve seat 20 surrounding the port 18, and a valve plate 22 seated thereon. In this example, the port 18 is divided into two. Although the planar contour of the valve plate 22 does not appear in the drawing, the valve plate 22 as a whole includes a portion that can be seated on the annular valve seat 20 of each of the pair of pressure relief valves 14 and can float from the valve seat. Is a disk-like elastic seat member, and a valve is provided along the edge of the shaft hole 34 through which the tip end portion 32 of the piston rod is passed by the annular jaw portion 30 of the piston rod 28 via the annular pressing members 24 and 26. It is fixed in a seated state on the seat. However, since the valve plate 22 has a hole through which the piston rod passes at the center, the valve plate 22 is a perforated disk member, that is, an annular member. The annular valve seat 20 includes an inner arcuate part 36 formed of a part of an annular part along the edge of the shaft hole 34, an outer arcuate part 38 along the outer periphery of the piston, A pair of side edge portions 40 extending radially between both ends of the arc-shaped portion are included.

  The valve plate 22 starts from its outer edge seated on the outer arcuate portion 38 of the annular valve seat when the differential pressure between the pressure acting on its lower side and the pressure acting on its upper side exceeds a certain predetermined value. As a result, it floats up from the valve seat and allows fluid to escape from the lower side to the upper side of the piston. The rise of the valve plate from the valve seat occurs so that the degree of bending toward the free end portion outside the root portion where the valve plate is fixed increases as the differential pressure acting on the valve plate increases, As a result, in response to a two-dimensional increase in fluid resistance in response to an increase in the moving speed of the piston, the opening degree of the valve is increased to allow a larger amount of fluid to escape from the port 18 through the annular valve seat 20, and An increase in the damping force of the shock absorber with respect to an increase in moving speed exhibits a proportional characteristic with a desired gradient.

  In this case, the pressure-sensitive relief valve 14 including the valve seat 20 and the valve plate 22 that opens and closes the valve seat 20 is formed as a pair of valve seats in which the valve seat 20 is disposed symmetrically with respect to the central axis of the piston. Since only one pair of pressure-sensitive relief valves that perform a damping function when moving downward along the central axis as viewed in FIG. As shown in FIG. 3, it is a simple bending deformation of the disk-shaped elastic sheet along the symmetry axis SS of the pair of valve seats 20, and the elastic sheet does not require any expansion and contraction along the sheet surface. is there. Therefore, even if the degree of floating of the valve plate 22 from the valve seat 20 is greatly increased in order to greatly increase the degree of opening of the heat sensitive relief valve 14, the deformation resistance of the valve plate 22 rapidly increases beyond the proportional relationship. However, as indicated by the one-dot chain line or two-dot chain line in the attached FIG. 8, the damping force does not rapidly increase beyond the proportional characteristic in the region where the piston speed is high.

  The pressure-sensing relief valve 16 may also have a configuration similar to that described above for the pressure-sensing relief valve 14 so that when the piston 10 moves upward in the figure relative to the cylinder 12, the same feeling is felt. It will be apparent that the desired valve opening characteristics of the pressure relief valve are obtained.

  In the embodiment shown in FIG. 2, two ports 18 are formed as valve ports surrounded by 20 in one valve seat, but the valve ports are provided in each valve seat 20 as shown in FIG. Only one may be provided, or three may be provided in each valve seat 20 as shown in FIG. 5, or more ports may be provided. 4 and 5, parts corresponding to those shown in FIG. 2 are denoted by the same reference numerals as in FIG.

  Further, the valve seat is provided with only a pair of pressure-sensitive relief valve seats that perform a damping function when the piston moves upward or downward as viewed in FIG. 1 symmetrically with respect to the central axis of the piston. However, the description of only one pair in this case is only one pair in the light of the function of the invention to make the deformation of the valve plate when opening and closing the valve simple bending deformation by the structure and arrangement of the valve seat. For example, as shown in FIG. 6, the region surrounded by the annular valve seat 20 is partitioned by a partition wall 42 that presents a contact surface with respect to the valve plate 22 in the same manner as the valve seat 20, and the two valves are simply viewed from the top. A structure that presents a seat is considered here as a single valve seat. Also in FIG. 6, portions corresponding to the portions shown in FIG. 2 are indicated by the same reference numerals as in FIG.

  While the present invention has been described in detail with respect to several embodiments thereof, it will be apparent to those skilled in the art that various modifications can be made to these embodiments within the scope of the present invention. .

FIG. 3 is a schematic cross-sectional view showing a shock absorber piston according to the present invention in a state where it is incorporated in a shock absorber according to one embodiment thereof, and a longitudinal section of the piston when the piston is viewed in the direction of an arrow by a cutting plane II in FIG. The figure which shows a surface. The end view of the valve seat part of the piston which looked at the piston in the arrow direction by the cut surface II-II in FIG. FIG. 3 is a partial perspective view showing a state in which the valve plate is lifted from the valve seat and the pressure-sensitive relief valve is opened in the piston shown in FIGS. 1 and 2. The figure similar to FIG. 2 which shows one modification of the shock absorber piston shown in FIG. The figure similar to FIG. 2 which shows another modification of the shock absorber piston shown in FIG. The figure similar to FIG. 2 which shows another modification of the shock absorber piston shown in FIG. Schematic which shows the deformation | transformation by valve opening of the disk shaped valve plate in a prior art. The graph which shows the problem in the operating characteristic of the pressure-sensitive relief valve by the conventional disc shaped valve plate as shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Piston, 12 ... Cylinder, 14.16 ... Pressure-sensitive relief valve, 18 ... Port, 20 ... Valve seat, 22 ... Valve plate, 24, 26 ... Pressing member, 28 ... Piston rod, 30 ... Annular jaw, 32 ... tip end of piston rod, 34 ... shaft hole, 36 ... inner arcuate part of valve seat, 38 ... outer arcuate part of valve seat, 40 ... side edge of seat

Claims (3)

  When the differential pressure acting on the front and back of the valve plate is less than a predetermined value, the valve plate is seated on the valve seat, but the differential pressure is greater than the predetermined value. In this case, the valve plate is a shock absorber piston having a pressure-sensitive relief valve that floats above the valve seat and opens a port surrounded by the valve seat to the outside of the valve seat. A pair of pressure-sensitive relief valves that perform a damping function when moving in the first direction along the direction, and that there is only one pair of pressure-sensitive relief valves that perform a damping function when the piston moves in the first direction. Including a pressure relief valve, the valve seats of the pair of pressure relief valves are arranged symmetrically with respect to the central axis of the piston, and the valve plate seated on the pair of valve seats is centered on the central axis of the piston Match the valve seat at the center Shock absorber piston, characterized in that an elastic sheet fixed disc shape.   Further, a pair of pressure-sensitive relief valves that perform a damping function when the piston moves along the central axis in a second direction opposite to the first direction, and is attenuated when the piston moves in the second direction. The pressure-sensitive relief valve that performs the function includes only one pair of pressure-sensitive relief valves, and the valve seats of the pair of pressure-sensitive relief valves are also arranged symmetrically with respect to the central axis of the piston. 2. The shock according to claim 1, wherein the valve plate seated on the valve seat is also a disc-shaped elastic sheet whose center coincides with the central axis of the piston and is fixed on the valve seat at the center. Absorber piston.   The pair of pressure-sensitive relief valves that perform a damping function when the piston moves in the first direction and the pair of pressure-sensitive relief valves that perform a damping function when the piston moves in the second direction are the center of the piston The shock absorber piston according to claim 2, wherein the shock absorber piston is alternately arranged around an axis.

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