JP2009281573A - Shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability in a shock absorber, by symmetrically arranging a plurality of valve bodies relative to the axis of a piston. <P>SOLUTION: This shock absorber 10 includes a cylinder 24 sealed with a working liquid, a main piston 34 slidingly inserted into the cylinder 24 and defining a first liquid chamber and a second liquid chamber in the cylinder 24, a plurality of extension side working liquid flow passages 56 arranged in the main piston 34 and communicating the first liquid chamber with the second liquid chamber, a plurality of valve seats 58 each arranged on an end surface of the main piston 34 for each of a plurality of extension side working liquid flow passages 56, and disc valves 66 each arranged for each of the plurality of valve seats 58 and having a plurality of valve opening-closing parts 70 seated on and leaving from the respective valve seats 58 by respectively different predetermined valve opening pressures. The plurality of valve bodies 72 each comprising the valve opening-closing part 70 and the valve seat 58, are symmetrically arranged relative to the axis of the main piston 34. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a shock absorber attached to a vehicle suspension device.

2. Description of the Related Art Conventionally, a shock absorber (hydraulic shock absorber) that is mounted on a vehicle suspension device is disclosed in Patent Document 1. The hydraulic shock absorber disclosed in Patent Document 1 includes a cylinder in which oil is sealed, a piston slidably fitted in the cylinder, a plurality of oil passages and seat portions provided in the piston, A disc valve is provided that is seated on and off the seat portion and controls the flow of the oil in the oil passage to generate a damping force. The disc valve has a plurality of radially extending arm portions having different widths, and a valve body portion formed at the tip of each arm portion, and the valve body portion is seated on the seat portion of the piston. Damping force is generated by controlling the flow of oil. Here, the hydraulic shock absorber of Patent Document 1 is configured so that the width of the arm portion is different. As a result, the valve body portion is sequentially opened according to the width of the arm portion, so that a sudden change in the damping force characteristic due to a sudden expansion of the flow path can be suppressed.
JP 2007-120726 A

  However, in the case of the hydraulic shock absorber described in Patent Document 1, depending on the arrangement of the arm portion and the valve body portion, the oil liquid flowing out from each valve body portion that has opened the valve collides with the inner wall of the cylinder, and is thus applied to the piston. In some cases, a biased force acts in a specific direction. Normally, a piston ring is provided on the outer periphery of the piston to prevent leakage of oil between the oil chambers. However, if the piston slides in the cylinder with a biased force applied to the piston, the piston ring is biased. Wear may occur and the durability of the shock absorber may be reduced.

  This invention is made | formed in view of such a condition, The objective is to provide the shock absorber which improved durability.

  In order to solve the above-described problems, a shock absorber according to an aspect of the present invention includes a cylinder in which a working fluid is sealed, a slidable insertion in the cylinder, and a first liquid chamber and a second liquid chamber in the cylinder. A defined piston, a plurality of hydraulic fluid channels provided in the piston and communicating with the first fluid chamber and the second fluid chamber, and a plurality of valve seat portions provided for each of the plurality of hydraulic fluid channels; And a disc valve having a plurality of valve opening / closing portions provided for each of the plurality of valve seat portions and seated at a predetermined opening pressure different from each other. The plurality of valve main body portions including the valve opening / closing portion and the valve seat portion are disposed symmetrically with respect to the central axis of the piston.

  According to this aspect, by arranging the plurality of valve main body portions symmetrically with respect to the central axis of the piston, when the piston is displaced, the forces acting on the two valve main body portions facing each other across the central axis are mutually Negate each other. As a result, the forces acting on the valve main body portions cancel each other, so that the bias of the force acting on the entire piston is reduced, and the durability of the shock absorber can be improved.

  The plurality of valve body portions are arranged so that when two valve body portions are formed in order of the valve opening pressure, the two valve body portions of each set face each other across the central axis of the piston. It may be provided. In this case, even in the initial stage when the displacement of the shock absorber starts, the bias of the force acting on the piston can be reduced, and the durability of the shock absorber can be further improved.

  Damping force characteristic variable means capable of changing the damping force characteristic may be provided in parallel with the plurality of valve body portions. Thereby, the damping force characteristic as a shock absorber can be set suitably, and the riding comfort of a vehicle can be improved.

  A tapered surface formed in a tapered shape may be formed on the valve seat portion, and a spherical member may be interposed between the tapered surface and the valve opening / closing portion to form the valve body portion. In this case, even if the disc valve is warped, the sealing performance of the valve main body can be ensured.

  You may provide the recessed part holding a spherical member in the site | part contact | abutted with the spherical member of a valve | bulb opening / closing part. In this case, the spherical member can be reliably supported. Further, the durability of the shock absorber can be improved by reducing the surface pressure of the disc valve.

  The valve opening pressures of the plurality of valve body portions may be made different by changing the taper angle of the tapered surface or the size of the spherical member for each valve body portion. In this case, the valve opening pressure of the valve body can be set to a desired magnitude.

  By changing the taper angle of the tapered surface of the valve seat portion and the size of the spherical member, the damping force characteristic after the valve opening of the valve main body portion may be adjustable. In this case, it is possible to set the damping force characteristic after the valve opening to a desired characteristic by changing the gap after the lift of the spherical member according to the combination of the size of the spherical member and the taper angle.

  By changing the taper angle in the middle of the taper surface, the damping force characteristic after the valve main body is opened may be adjustable. In this case, the damping force characteristic after the valve main body is opened can be adjusted to a desired characteristic.

  A tapered surface formed in a tapered shape may be formed on the valve seat portion, a spherical convex portion may be formed on the valve opening / closing portion, and the spherical convex portion may be pressed against the tapered surface to form the valve main body portion. In this case, even if the disc valve is warped, the sealing performance of the valve main body can be ensured. Further, if the spherical convex portion is formed by pressing the valve opening / closing portion of the disc valve, the number of parts can be reduced, so that the cost can be reduced.

  According to the present invention, the durability of the shock absorber can be improved.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a partial cross-sectional view illustrating a configuration of a suspension 12 including a shock absorber according to the present embodiment. The suspension 12 includes a shock absorber 10 and a spring 14, and an upper part is connected to an upper support 16.

  The upper support 16 is used to attach the upper end of the piston rod 18 of the shock absorber 10 and the upper end of the spring 14 to a vehicle body (not shown). The piston rod 18 of the shock absorber 10 is fixed to the upper support 16 by a nut 20. Moreover, the lower end part (not shown) of the shock absorber 10 is connected to the seat part of the lower arm via a bush. Therefore, the shock absorber 10 attenuates the vertical vibration of the vehicle body by the expansion and contraction resistance when the piston rod 18 extends and contracts.

  The spring 14 has an upper end supported by an upper spring seat 22 of the upper support 16 and a lower end supported by a lower spring seat 26 fixed around the cylinder 24 of the shock absorber 10. Accordingly, the spring 14 can support the weight of the vehicle body and reduce the impact from the road surface.

  A dust cover 28 is provided around the shock absorber 10 to prevent dust and dirt from entering the cylinder 24 when the piston rod 18 is expanded and contracted. A bound stopper 30 is fixed to the upper portion of the dust cover 28. The bound stopper 30 regulates the displacement when the piston rod 18 contracts, that is, when the wheel bounces and the cylinder 24 of the shock absorber 10 is displaced in the arrow A direction. By regulating the displacement in this way, it is possible to regulate the upward displacement of the lower arm and prevent contact between the lower arm and the vehicle body. The bound stopper 30 is formed of, for example, an elastic member such as a rubber material or urethane, and is initially considered to exhibit soft nonlinear characteristics and to secure roll rigidity during turning.

  FIG. 2 is a partial cross-sectional view for explaining the structure of the shock absorber 10 according to the present embodiment. In the shock absorber 10, a valve assembly 32 slidable in an extending direction (arrow A direction in the figure) or a shrinking direction (arrow B direction in the figure) is inserted into a cylindrical cylinder 24 filled with hydraulic fluid. Has been. The valve assembly 32 includes a main piston 34 and a sub piston 36 fixed to the lower end portion of the piston rod 18. The main piston 34 divides the inside of the cylinder 24 into two to define a first liquid chamber 38 on the wheel side and a second liquid chamber 40 on the bound stopper 30 side. The sub piston 36 is fixed above the main piston 34. The main piston 34 and the sub piston 36 are provided coaxially with the cylinder 24.

  A piston ring 76 is fitted on the outer periphery of the main piston 34. The piston ring 76 serves to prevent the hydraulic fluid from leaking between the first liquid chamber 38 and the second liquid chamber 40.

  The main piston 34 is provided with a plurality of extending-side hydraulic fluid channels 56 along the axial direction. The extension side hydraulic fluid channel 56 is formed so as to penetrate the main piston 34, and communicates the first liquid chamber 38 and the second liquid chamber 40. An annular valve seat 58 protrudes from the end surface of the main piston 34 on the first liquid chamber 38 side and around each opening of the plurality of extension-side hydraulic fluid channels 56. The inner surface of the valve seat 58 is formed in a tapered surface that expands toward the first liquid chamber 38 side. In addition, an annular boss portion 60 projects from the inner peripheral portion of the main piston 34.

  On the first liquid chamber 38 side of the main piston 34, a plate-like extension side disk valve 66 is attached coaxially with the main piston 34. Although the detailed shape will be described later, the extension-side disk valve 66 includes an annular inner peripheral portion 68 and a plurality of valve opening / closing portions 70 that protrude radially outward from the edge of the inner peripheral portion 68 at a predetermined interval. Have. The plurality of valve opening / closing sections 70 are provided so as to correspond to the plurality of valve seat sections 58 of the main piston 34, respectively. The extension-side disc valve 66 has an inner peripheral portion 68 clamped by a boss portion 60 and a washer 64 and fastened by a nut 62. The plurality of valve opening / closing portions 70 of the extension-side disc valve 66 are configured to be separated from the corresponding valve seat portions 58. Note that the end portion on the second liquid chamber 40 side of the extension side working fluid flow path 56 is open to the second liquid chamber 40.

  When the main piston 34 is displaced in the extending direction and the fluid pressure in the second fluid chamber 40 increases, and the differential pressure between the first fluid chamber 38 and the second fluid chamber 40 reaches a predetermined differential pressure, the valve opening / closing part 70 It bends toward the first liquid chamber 38 and leaves the valve seat 58. As a result, the extension-side hydraulic fluid flow path 56 is opened to the first liquid chamber 38, and the hydraulic fluid in the second liquid chamber 40 flows to the first liquid chamber 38 side via the extension-side hydraulic fluid flow path 56. Resistance occurs and damping force is generated. Here, a set of the valve seat portion 58 and the valve opening / closing portion 70 corresponding thereto is referred to as a “valve body portion 72”. Therefore, the shock absorber 10 has a plurality of valve main body portions 72. In the present embodiment, the plurality of valve main bodies 72 are configured to have different predetermined valve opening pressures. The plurality of valve main bodies 72 constitute an extension-side damping force generation mechanism that generates a damping force when the main piston 34 is displaced in the extension direction.

  Although the extension side damping force generation mechanism has been described above, the shock absorber 10 also has a contraction side damping force generation mechanism that generates a damping force when the main piston 34 is displaced in the contraction direction. Although not shown in FIG. 1, the main piston 34 is provided with a plurality of contraction-side working fluid flow paths along which the working fluid flows when displaced to the contraction side. A valve seat portion projects from the end surface of the liquid chamber 40 around the opening of each contraction-side hydraulic fluid channel. Further, on the second liquid chamber 40 side of the main piston 34, a contraction side disk valve 74 having a valve opening / closing portion provided so as to be attached to and detached from each valve seat portion is attached.

  When the main piston 34 is displaced in the contraction direction and the fluid pressure in the first fluid chamber 38 increases, and the differential pressure between the first fluid chamber 38 and the second fluid chamber 40 reaches a predetermined differential pressure, the valve opening / closing portion It bends to the two-liquid chamber 40 side and separates from the valve seat. As a result, the contraction-side working fluid flow path is opened to the second fluid chamber 40, and the working fluid in the first fluid chamber 38 passes outside the cup 44 disposed on the contraction-side working fluid flow path and the outer periphery of the sub-piston 36. By flowing toward the second liquid chamber 40, a flow resistance is generated and a damping force is generated. Also in the compression side damping force generation mechanism, the plurality of valve main body portions are configured to have different predetermined valve opening pressures.

  The shock absorber 10 according to the present embodiment includes a damping force characteristic variable mechanism 80 that can change the damping force characteristic. Hereinafter, the damping force characteristic variable mechanism 80 will be described.

  In the shock absorber 10, a flow path outer cylinder 46 having an open end 46 a in the first liquid chamber 38 is formed at the tip of the piston rod 18. A control rod 48 that is coaxial with the central axis of the piston rod 18 and is rotatable is inserted into the piston rod 18.

  A flow path inner cylinder 50 that is rotatable within the flow path outer cylinder 46 is fixed to the tip of the control rod 48. A channel inner cylinder opening 52 is formed on the side surface of the channel inner cylinder 50, and a rod opening 54 is formed on the side surface of the channel outer cylinder 46. Therefore, the control rod 48 is rotationally driven by a drive source such as an absorber motor (not shown), and the flow path inner cylinder 50 is rotated with respect to the flow path outer cylinder 46 so that the flow path inner cylinder opening 52 and the rod opening 54 are The phase of can be changed. Then, the first liquid chamber 38 and the second liquid chamber are interposed via the internal space of the piston rod 18 by adjusting the opening area formed by overlapping the inner cylinder opening 52 and the rod opening 54. The flow rate of the working fluid flowing between 40 and 40 can be changed.

  When the damping force is different between the expansion side and the contraction side, the opening area formed by the overlap between the flow path inner cylinder opening 52 and the rod opening 54 is adjusted between the contraction exclusive flow path and the expansion dedicated flow path. Good. In addition, the flow path of the hydraulic fluid that passes through the internal space of the piston rod 18 passes through the outside of the cup 44 through the opening 53 formed on the bottom surface of the cup 44 when the shock absorber 10 is displaced to the extension side, for example. There are a flow path that flows into the second liquid chamber 40 and a flow path that flows into the second liquid chamber 40 through the sub piston flow path 37 provided inside the cup 44 and inside the sub piston 36.

  In such a shock absorber 10, for example, the sub piston 36 side is set to have a low damping force. Then, the flow area to the main piston 34 is increased by decreasing the opening area formed by the overlap between the flow path inner cylinder opening 52 and the rod opening 54, and the damping force as the shock absorber 10 is increased. be able to. Further, if the opening area formed by the overlap can be arbitrarily set from the fully closed state to the fully open state, the damping force can be continuously adjusted.

  FIG. 3 is a plan view of the extension-side damping force generation mechanism according to the present embodiment. FIG. 3 shows a state in which the disc valve 66 and the main piston 34 are viewed from the first liquid chamber 38 side in FIG. In FIG. 3, illustrations of the nut 62, the washer 64, the contraction-side hydraulic fluid passage, and the like are omitted.

  As shown in FIG. 3, in the present embodiment, the main piston 34 has a first extension side hydraulic fluid passage 56a, a second extension side hydraulic fluid passage 56b, a third extension side hydraulic fluid passage 56c, and a fourth extension. Six extension side hydraulic fluid channels 56 are formed, that is, a side hydraulic fluid channel 56d, a fifth extension side hydraulic fluid channel 56e, and a sixth extension side hydraulic fluid channel 56f. A first valve seat 58a, a second valve seat 58b, a third valve seat 58c, and a fourth valve seat are provided around the respective openings of the first to sixth extension hydraulic fluid passages 56a to 56f. Six valve seats 58, that is, a part 58d, a fifth valve seat part 58e, and a sixth valve seat part 58f, are projected.

  The disc valve 66 includes a first valve opening / closing part 70a, a second valve opening / closing part 70b, a third valve opening / closing part 70c, a fourth valve opening / closing part 70d, a fifth valve opening / closing part 70e, and a sixth valve opening / closing part 70f. Six valve opening / closing portions 70 are formed so as to protrude radially outward from the inner peripheral portion 68. The 1st-6th valve opening-and-closing part 70a-70f is formed so that it may detach | separate from the 1st-6th valve-seat part 58a-58f, respectively. Accordingly, the shock absorber 10 includes the first valve body 72a, the second valve body 72b, the third valve body 72c, the fourth valve body 72d, the fifth valve body 72e, and the sixth valve body 72f. One valve body 72 is provided. The first to sixth valve main body portions 72a to 72f are formed at equal intervals in the circumferential direction.

  In the shock absorber 10 according to the present embodiment, the taper angles of the tapered surfaces formed on the inner surfaces of the first to sixth valve seat portions 58a to 58f are made different. Specifically, the first valve seat portion 58a is formed to have the largest taper angle, and the second valve seat portion 58b, the third valve seat portion 58c, the fourth valve seat portion 58d, and the fifth valve seat. The taper angle is formed in the order of the portion 58e and the sixth valve seat portion 58f.

  Thus, by changing the taper angles of the first to sixth valve seat portions 58a to 58f, the pressure applied to the first to sixth valve opening / closing portions 70a to 70f when the main piston 34 is displaced changes. The first to sixth valve main body portions 72a to 72f can have different valve opening pressures. Since the valve opening pressure decreases as the taper angle increases, in this embodiment, the valve opening pressure of the first valve body 72a is the smallest, and the second valve body 72b, the third valve body 72c, and the fourth valve. The valve opening pressure increases in the order of the main body 72d, the fifth valve main body 72e, and the sixth valve main body 72f.

  By the way, when the shock absorber 10 is displaced in the extending direction and the first to sixth valve body portions 72 a to 72 f are opened, the hydraulic fluid flowing out from the opened valve body portions 72 collides with the inner wall of the cylinder 24. Thus, a force directed radially inward acts on the main piston 34. Therefore, depending on how the valve body 72 is arranged, the force acting on the main piston 34 may be biased in a specific direction. When the main piston 34 having such a biased force slides inside the cylinder 24, the piston ring 76 is unevenly worn, which may reduce the durability of the shock absorber 10.

  Therefore, in the shock absorber 10 according to the present embodiment, the first to sixth valve main body portions 72 a to 72 f are arranged symmetrically with respect to the central axis C of the main piston 34. FIG. 4 is a diagram for explaining the force acting on the main piston 34 when the first to sixth valve main body portions 72a to 72f are opened. When the main piston 34 is displaced in the extending direction and the first to sixth valve body portions 72a to 72f are opened, the hydraulic fluid flows out from each of the first to sixth valve body portions 72a to 72f as shown in FIG. And collides with the inner wall of the cylinder 24. Thereby, although the force which goes to the direction of the central axis C of the main piston 34 generate | occur | produces in each of the 1st-6th valve main-body parts 72a-72f, in this Embodiment, it is the 1st-6th valve main-body parts 72a-72f. Are symmetrically arranged with respect to the central axis C of the main piston 34, so that the forces acting on the two valve body portions 72 facing each other across the central axis C cancel each other. That is, the force Fa acting on the first valve body 72a cancels out the force Fb acting on the second valve body 72b, and the force Fc acting on the third valve body 72c cancels with the force Fd acting on the fourth valve body 72d. Accordingly, the force Fe acting on the fifth valve body 72e cancels out the force Ff acting on the sixth valve body 72f.

  As described above, the forces acting on the valve main body portions 72 cancel each other, whereby the bias of the force acting on the entire main piston 34 can be reduced. Therefore, uneven wear of the piston ring 76 is suppressed, and the durability of the shock absorber 10 can be improved. Further, since the bias of the force acting on the main piston 34 is reduced, the frictional force when the piston ring 76 slides is reduced, so that the riding comfort of the vehicle can be improved.

  Furthermore, in the shock absorber 10 according to the present embodiment, when the first to sixth valve main body portions 72a to 72f are formed in pairs of the valve main body portions 72 in the order of the valve opening pressure, The two valve main body portions 72 of the set are arranged so as to face each other across the central axis C of the main piston 34.

  In the present embodiment, as described above, since the valve opening pressure is increased in the order of the first to sixth valve body portions 72a to 72f, the first valve body portion 72a and the second valve body portion 72b Three sets of the first set, the second set of the third valve body 72c and the fourth valve body 72d, and the third set of the fifth valve body 72e and the sixth valve body 72f are made. The first valve body 72a and the second valve body 72b face each other, the second set of the third valve body 72c and the fourth valve body 72d face each other, and the third set of the fifth valve body 72e and The sixth valve body 72f is disposed so as to face each other.

  FIG. 5 is a diagram for explaining the force acting on the main piston 34 when the first valve body 72a and the second valve body 72b are opened. When the main piston 34 is displaced in the extending direction, the pressure difference between the first liquid chamber 38 and the second liquid chamber 40 usually increases gradually. Therefore, first, the first valve body having the smallest valve opening pressure. The part 72a is opened, and the second valve body part 72b having the second lowest opening pressure is then opened. In the present embodiment, the first valve main body portion 72a and the second valve main body portion 72b are disposed so as to face each other with the central axis C of the main piston 34 interposed therebetween, and therefore the force Fa acting on the first valve main body portion 72a. And the force Fb acting on the second valve body 72b cancel each other, and the bias of the force acting on the main piston 34 at the stage when the valve is opened from the first valve body 72a to the second valve body 72b can be reduced.

  Thereafter, when the differential pressure between the first liquid chamber 38 and the second liquid chamber 40 increases, the third valve body 72c and the fourth valve body 72d are further opened. Since the part 72c and the fourth valve body part 72d are arranged to face each other with the central axis C interposed therebetween, the force acting on the third valve body part 72c and the force acting on the fourth valve body part 72d cancel each other, The bias of the force acting on the main piston 34 at the stage where the first valve body 72a to the fourth valve body 72d are opened can be reduced.

  As described above, in the shock absorber 10 according to the present embodiment, the first to sixth valve body portions 72a to 72f are formed in pairs of the valve body portions 72 in order of the valve opening pressure. Since the two valve main body portions 72 of each set are arranged so as to face each other with the central axis C of the main piston 34 therebetween, the main piston 34 works even at the initial stage where the shock absorber 10 starts to be displaced. Force bias can be reduced. Therefore, uneven wear of the piston ring 76 can be further suppressed, and the durability of the shock absorber 10 can be further improved. In addition, the ride comfort of the vehicle can be further improved. Here, the extension side damping force generation mechanism has been described, but the same applies to the contraction side damping force generation mechanism.

  FIG. 6 is a diagram showing a hydraulic circuit diagram of the shock absorber 10 according to the present embodiment. As shown in FIG. 6, in the shock absorber 10, the first to sixth valve main body portions 72 a to 72 f and the damping force characteristic variable mechanism 80 are provided in parallel.

  FIGS. 7A to 7C are diagrams for explaining the damping force characteristics of the shock absorber 10 according to the present embodiment. 7A to 7C, the vertical axis represents the damping force, and the horizontal axis represents the piston speed. FIG. 7A shows the damping force characteristic of the disc valve 66. FIG. 7B shows the damping force characteristic of the damping force characteristic variable mechanism 80. FIG. 7C shows the damping force characteristic of the shock absorber 10 as a whole.

  FIGS. 8A to 8C and FIGS. 9A to 9C illustrate, as a comparative example, damping force characteristics of a shock absorber using a disk valve having only one valve opening pressure. FIG. 8A to 8C and FIGS. 9A to 9C, the vertical axis represents the damping force, and the horizontal axis represents the piston speed. FIG. 8A and FIG. 9A show the damping force characteristics of the disc valve having only one valve opening pressure. FIG. 8B and FIG. 9B show the damping force characteristics of the damping force characteristic variable mechanism. FIG. 8C and FIG. 9C show the damping force characteristics of the shock absorber as a whole.

  First, the damping force characteristics of the shock absorber according to the comparative example shown in FIGS. 8 (a) to 8 (c) show the damping force characteristics when trying to ensure the damping force when the piston speed is very low in a shock absorber using a disk valve having only one valve opening pressure. Show. In the damping force characteristic of the disc valve shown in FIG. 8A, the valve opening pressure is one disc valve, so the differential pressure between the first liquid chamber and the second liquid chamber becomes a predetermined valve opening pressure. When the valve is opened, a one-stage damping force characteristic is obtained in which the damping force increases in proportion to the piston speed. In addition, the shock absorber damping force variable mechanism according to the comparative example can switch the slope of the damping force characteristic in six steps as shown in FIG. 8B, but the piston speed is in a very low speed range. In order to ensure the damping force, the slope of the damping force characteristic on the hard side where the damping force is high is set large. When the damping force characteristic variable mechanism is set in this way, as shown in FIG. 8C, the damping force in the high speed region of the shock absorber as a whole becomes too large, so that the riding comfort is deteriorated. . In addition, the difference in damping force between the number of stages in the high speed region of the piston speed becomes non-uniform.

  Next, the damping force characteristics of the shock absorber according to the comparative example shown in FIGS. 9 (a) to 9 (c) show damping force characteristics when the damping force is not excessively increased in the high speed region of the piston speed in a shock absorber using a disk valve having only one valve opening pressure. Is shown. The damping force characteristics of the disc valve shown in FIG. 9A are the same as those in FIG. In addition, the damping force characteristic variable mechanism can switch the inclination of the damping force characteristic to six stages as shown in FIG. 9B, but the damping force does not become excessively large in the piston speed range. As described above, the slope of the damping force characteristic on the hardware side having a high damping force is set small. When the damping force characteristic variable mechanism is set in this way, as shown in FIG. 9C, the shock absorber as a whole has insufficient damping force in the region where the piston speed is very low, and the riding comfort deteriorates. End up. In addition, the difference in damping force between the number of stages in the high speed region of the piston speed becomes non-uniform.

  Returning to FIG. 7, the damping force characteristic of the shock absorber 10 according to the present embodiment will be described. As described above, in the present embodiment, the first to sixth valve main body portions 72a to 72f and the damping force characteristic variable mechanism 80 are provided in parallel. Therefore, the damping force characteristics of the disc valve shown in FIG. 7A are the damping force characteristics 101 of the first valve body 72a, the damping force characteristics 102 of the second valve body 72b, and the third valve body 72c. Six different valve opening pressures including a damping force characteristic 103, a damping force characteristic 104 of the fourth valve body 72d, a damping force characteristic 105 of the fifth valve body 72e, and a damping force characteristic 106 of the sixth valve body 72f. There exists a damping force characteristic having

  In addition, as shown in FIG. 7 (b), the setting of the damping force characteristic variable mechanism 80 can switch the slope of the damping force characteristic to 6 levels, and secures the damping force on both the soft side and the hard side. It is set to be. When the damping force characteristic of the damping force characteristic variable mechanism 80 is set in this way, as shown in FIG. 7C, the damping force in the high speed range is also secured while ensuring the damping force in the very low speed range. The size can be reduced to an appropriate size according to the number of switching stages of the variable mechanism 80. Further, it becomes possible to make the difference in damping force substantially uniform between the number of stages in the high speed region of the piston speed.

  Thus, in the shock absorber 10 according to the present embodiment, the first to sixth valve main body portions 72a to 72f and the damping force characteristic variable mechanism 80 are configured to be provided in parallel. The damping force characteristic can be suitably set, and the riding comfort of the vehicle can be improved.

  FIG. 10 is a view for explaining a first modification of the valve main body. In the valve main body 72 according to the first modification, a steel ball 174 is interposed between a tapered surface 58 g formed on the valve seat 58 and the upper surface of the valve opening / closing part 70 of the disk valve 66.

  Since the disc valve 66 is a plate-like member, when the disc valve 66 is tightened by the nut 62 to give a predetermined valve opening pressure, the disc valve 66 is warped, and the upper surface of the valve opening / closing portion 70 and the valve seat are There is a possibility that a gap is generated between the seat 58 and the seating surface of the portion 58 and the sealing performance is deteriorated.

  Therefore, as in the first modification, a steel ball 174 is interposed between the tapered surface 58g formed on the valve seat portion 58 and the upper surface of the valve opening / closing portion 70 of the disc valve 66, thereby providing a sealing property. As a result, the valve body 72 can be reliably closed.

  Also in the first modified example, by making the taper angle of the tapered surface of the valve seat portion 58 different for each valve body portion 72, each valve body portion 72 can have a different valve opening pressure. Also, by making the size of the steel ball 174 different for each valve main body 72, each valve main body 72 can have a different valve opening pressure. In this case, the valve opening pressure decreases as the size of the steel ball 174 increases.

  FIG. 11 is a view for explaining a second modification of the valve main body. Similarly to the first modification, the valve body 72 according to the second modification also has a steel ball 174 between the tapered surface 58g formed on the valve seat 58 and the upper surface of the valve opening / closing part 70 of the disk valve 66. However, in the valve main body 72 according to the second modified example, a recess 176 for holding the steel ball 174 is further provided at a portion of the valve opening / closing portion 70 that contacts the steel ball 174. Yes. By providing the recess 176 in the valve opening / closing part 70, the steel ball 174 can be reliably supported. Further, the durability of the shock absorber 10 can be improved by reducing the surface pressure of the disc valve 66.

  12A and 12B are views for explaining a third modification of the valve main body. The valve body according to the third modification has the same configuration as the valve body according to the second modification, but changes the taper angle of the tapered surface 58g of the valve seat 58 and the size of the steel ball 174. This makes it possible to adjust the damping force characteristics after the valve body portion is opened.

  FIG. 12A shows a valve main body 72 a in which the taper angle of the tapered surface 58 g is increased and a large steel ball 174 is interposed between the tapered surface 58 g and the valve opening / closing portion 70. On the other hand, FIG. 12B shows a valve main body 72 b in which the taper angle of the tapered surface 58 g is reduced and a small steel ball 174 is interposed between the tapered surface 58 g and the valve opening / closing portion 70. Here, the valve main body 72a shown in FIG. 12 (a) and the valve main body 72b shown in FIG. 12 (b) are tapered so that the seal diameter for sealing the expansion-side working fluid flow path 56 becomes the same seal diameter. The size of the corners and steel balls are designed.

  When the valve main body portion is designed in this manner, if the steel ball 174 is lifted by the same amount, the valve main body portion 72a is connected to the steel ball 174 as shown in the right-side drawings of FIGS. Although the gap with the tapered surface 58g is increased, the gap between the steel ball 174 and the tapered surface 58g is reduced in the valve main body 72b.

  FIGS. 13A and 13B are diagrams for explaining the damping force characteristics of the valve body according to the third modification. FIG. 13A shows the damping force characteristics of the valve main body 72a in the case of the large steel ball 174 and the large taper angle shown in FIG. FIG. 13B shows the damping force characteristics of the valve main body 72b in the case of the small steel ball 174 and the small taper angle shown in FIG.

  The valve body portions 72a and 72b have the same valve opening pressure because they are designed to have the same seal diameter. However, as described above, the steel ball 174 after the steel ball 174 is lifted and the tapered surface 58g Since the gap is different, the damping force characteristics after the valve opening are different. That is, in the case of the valve body 72a, the inclination of the damping force characteristic is small as shown in FIG. 13A, but in the case of the valve body 72b, the damping force characteristic is shown in FIG. 13B. The slope increases. Thus, even if the valve opening pressure is the same, the damping force characteristic after the valve opening is changed to a desired characteristic by changing the gap after the lift of the steel ball 174 depending on the combination of the size of the steel ball 174 and the taper angle. It becomes possible to set to.

  14A and 14B are views for explaining a fourth modification of the valve main body. The valve main body according to the fourth modification can adjust the damping force characteristic after the valve main body is opened by changing the taper angle in the middle of the tapered surface 58g of the valve seat 58. The valve main body 72a shown in FIG. 14A has a small taper angle from the opening end 58h of the valve seat 58 to the middle of the tapered surface, but the end of the extending-side hydraulic fluid channel 56 from the middle of the tapered surface. Up to this point, the taper angle is increased. On the other hand, the valve main body 72b shown in FIG. 14B has a large taper angle from the open end 58h of the valve seat 58 to the middle of the tapered surface, but from the middle of the tapered surface to the extension side working fluid channel 56. The taper angle is reduced to the end.

  FIGS. 15A and 15B are diagrams for explaining the damping force characteristics of the valve body according to the fourth modification. FIG. 15A shows the damping force characteristics of the valve main body 72a shown in FIG. FIG. 15B shows the damping force characteristics of the valve main body 72b shown in FIG.

  As shown in FIG. 15A, in the valve main body 72a, the taper surface 58g is formed so that the taper angle changes from “large” to “small” in the middle of the taper surface. Although the slope of the damping force characteristic is small, the slope of the damping force characteristic is large when the piston speed is high. Further, as shown in FIG. 15B, in the valve main body 72b, the taper surface 58g is formed so that the taper angle changes from “small” to “large” in the middle of the taper surface. The slope of the damping force characteristic is large in the low speed range, but the slope of the damping force characteristic is large in the high speed region of the piston speed.

  In this way, by changing the taper angle in the middle of the tapered surface 58g of the valve seat portion 58, the damping force characteristic after the valve opening of the valve main body portion can be adjusted to a desired characteristic. In the fourth modification, the taper angle is changed only once in the middle of the tapered surface 58g. However, the present invention is not limited to this, and the taper angle may be changed a plurality of times.

  FIG. 16 is a view for explaining a fifth modification of the valve body. In the fifth modification, a tapered surface 58g formed in a taper shape is formed on the valve seat portion 58, a spherical convex portion 90 is formed on the valve opening / closing portion 70, and the spherical convex portion 90 is pressed against the tapered surface 58g. A valve main body 72 is configured.

  The spherical convex portion 90 is for improving the sealing performance of the valve main body portion instead of the steel ball 174 used in the first to fourth modifications. The spherical convex portion 90 can be formed by pressing the valve opening / closing portion 70 of the disc valve 66. Since the number of parts is reduced by forming the spherical convex portion 90 by press working, the cost can be reduced. Further, since the steel ball 174 is unnecessary, the weight can be reduced. Further, because of the press working, variations in the position, height, and size of the spherical convex portion 90 can be reduced.

  FIGS. 17A and 17B are diagrams for explaining the design of the valve body according to the fifth modification. 17A shows the valve main body 72 after the spherical convex portion 90 is pressed against the tapered surface 58g, and FIG. 17B shows the disc valve 66 before the press contact. When the disc valve 66 is attached to the main piston 34 by a nut 62 (not shown), an initial installation load is applied by tightening the disc valve 66. At this time, as shown in FIG. 17A, the disc valve 66 is warped. appear. At this time, since the center position of the spherical convex portion 90 is deviated, it is preferable to set the center position in advance in consideration of the deviation amount.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  In FIG. 3, the shock absorber 10 having six valve main bodies 72 is shown, but the number of valve main bodies 72 is not limited to this, and any number of valve main bodies 72 may be provided as long as they are even numbers.

It is a fragmentary sectional view explaining the composition of the suspension containing the shock absorber concerning this embodiment. It is a fragmentary sectional view for demonstrating the structure of the shock absorber which concerns on this Embodiment. It is a top view of the expansion side damping force generation mechanism which concerns on this Embodiment. It is a figure for demonstrating the force which acts on a main piston when the 1st-6th valve main-body part opens. It is a figure for demonstrating the force which acts on a main piston when a 1st valve main-body part and a 2nd valve main-body part open. It is a figure which shows the hydraulic-pressure circuit diagram of the shock absorber which concerns on this Embodiment. FIGS. 7A to 7C are diagrams for explaining the damping force characteristics of the shock absorber according to the present embodiment. FIGS. 8A to 8C are diagrams for explaining the damping force characteristics of a shock absorber using a disk valve having only one valve opening pressure as a comparative example. FIGS. 9A to 9C are diagrams for explaining the damping force characteristics of a shock absorber using a disk valve having only one valve opening pressure as a comparative example. It is a figure for demonstrating the 1st modification of a valve main-body part. It is a figure for demonstrating the 2nd modification of a valve main-body part. 12A and 12B are views for explaining a third modification of the valve main body. FIGS. 13A and 13B are diagrams for explaining the damping force characteristics of the valve body according to the third modification. 14A and 14B are views for explaining a fourth modification of the valve main body. FIGS. 15A and 15B are diagrams for explaining the damping force characteristics of the valve body according to the fourth modification. It is a figure for demonstrating the 5th modification of a valve main-body part. FIGS. 17A and 17B are diagrams for explaining the design of the valve body according to the fifth modification.

Explanation of symbols

  10 Shock Absorber, 18 Piston Rod, 24 Cylinder, 34 Main Piston, 36 Sub Piston, 38 1st Fluid Chamber, 40 2nd Fluid Chamber, 56 Extension Side Working Fluid Channel, 58 Valve Seat, 62 Nut, 66 Disc Valve 70 Valve opening / closing part, 72 Valve body part, 76 Piston ring, 80 Damping force characteristic variable mechanism, 90 Spherical convex part, 174 Steel ball, 176 Concave part.

Claims (9)

A cylinder filled with hydraulic fluid;
A piston that is slidably inserted in the cylinder, and that defines a first liquid chamber and a second liquid chamber in the cylinder;
A plurality of hydraulic fluid flow paths provided in the piston and communicating the first liquid chamber and the second liquid chamber;
A plurality of valve seat portions provided for each of the plurality of hydraulic fluid flow paths;
A disc valve having a plurality of valve opening and closing portions provided for each of the plurality of valve seat portions, each of which is separated from and seated at a predetermined valve opening pressure;
With
A shock absorber, wherein a plurality of valve main body portions including the valve opening / closing portion and the valve seat portion are arranged symmetrically with respect to a central axis of the piston.   When the plurality of valve body portions are formed in pairs of the valve body portions in order of the magnitude of the valve opening pressure, the two valve body portions of each set sandwich the central axis of the piston. The shock absorber according to claim 1, wherein the shock absorber is disposed so as to face each other.   The shock absorber according to claim 1 or 2, wherein a damping force characteristic variable means capable of changing the damping force characteristic is provided in parallel with the plurality of valve body portions.   A tapered surface formed in a tapered shape is formed on the valve seat portion, and a spherical member is interposed between the tapered surface and the valve opening / closing portion to form the valve main body portion. The shock absorber according to any one of 1 to 3.   The shock absorber according to claim 4, wherein a concave portion for holding the spherical member is provided at a portion of the valve opening / closing portion that contacts the spherical member.   6. The valve opening pressures of the plurality of valve main body portions are made different by changing the taper angle of the tapered surface and the size of the spherical member for each valve main body portion. The listed shock absorber.   The damping force characteristic after the valve opening of the valve body can be adjusted by changing the taper angle of the tapered surface of the valve seat and the size of the spherical member. The shock absorber according to any one of the above.   The shock absorber according to any one of claims 4 to 7, wherein a damping force characteristic after the valve main body is opened can be adjusted by changing a taper angle in the middle of the tapered surface.   A tapered surface formed in a tapered shape is formed on the valve seat portion, a spherical convex portion is formed on the valve opening / closing portion, and the spherical convex portion is pressed against the tapered surface to form the valve main body portion. The shock absorber according to any one of claims 1 to 3.

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