JP2006183775A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress sharp fluctuation of a pressure of oil liquid in opening of a disc valve in a hydraulic shock absorber. <P>SOLUTION: A piston 5 connected to a piston rod 6 is slidably fit into a cylinder 2 sealing the oil liquid. A flow of the oil liquid caused in an extension side oil passage 11 by sliding of the piston 6 is controlled by an orifice 24 and the disc valve 21 to generate damping force. Protruding parts 25A are formed on both radial ends of a disc 25 composing the disc valve 21, discs laminated in a back face side of the protruding part 25 are warped, and a disc 24 is pressed against an outer circumference seat part 20 at a predetermined set load. In the disc valve 21, since lifting is gradually carried out from a portion separated from the protruding part 25A with a small set load toward a protruding part 25A vicinity with a large set load during valve opening, sharp change of the damping force is suppressed, and generation of noise and deterioration of ride comfort can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic shock absorber used in a suspension device of a vehicle such as an automobile.

  In general, a cylindrical hydraulic shock absorber used in an automobile suspension device has a piston in which a piston rod is connected slidably fitted in a cylinder in which oil is sealed. The flow of the oil generated by sliding is controlled by a damping force generation mechanism including an orifice and a disk valve to generate a damping force. At this time, as shown in FIG. 10, in the low speed region of the piston speed, the orifice generates a damping force having an orifice characteristic that is substantially proportional to the square of the piston speed, and when the piston speed increases, the disk valve opens. A damping force having a valve characteristic substantially proportional to the piston speed is generated to suppress an excessive increase in the damping force.

In general, a disk valve of a damping force generation mechanism is given a predetermined amount of deflection so as to open when the oil pressure reaches a predetermined pressure, as described in Patent Document 1, for example. It is pressed against the seat (valve seat) with a set load.
Japanese Utility Model Publication No. 58-12746

  However, in the above-described conventional hydraulic shock absorber, the disc valve is pressed against the seat portion with a uniform set load. Therefore, when the oil pressure reaches the valve opening pressure, the disk valve is opened at once, and suddenly There is a problem that the fluctuation of the pressure is generated, noise is generated, and the ride comfort of the vehicle is deteriorated by a sudden change in the damping force from the orifice characteristic to the valve characteristic.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a hydraulic shock absorber capable of suppressing rapid fluctuations in the pressure of oil when the disk valve is opened.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a cylinder in which oil is sealed, a piston slidably fitted in the cylinder, and sliding of the piston in the cylinder. In a hydraulic shock absorber provided with a disk valve that generates a damping force by controlling the flow of oil liquid generated by
The disc valve includes an annular seat portion and a plurality of stacked discs seated on the seat portion, and a convex portion is formed on a part of the plurality of discs to press the disc valve against the seat portion. The set load is large in the vicinity of the convex portion, and is small in a portion away from the convex portion.
A hydraulic shock absorber according to a second aspect of the present invention is characterized in that, in the configuration of the first aspect, the convex portions are disposed at both ends in the diameter direction of the disk.

According to the hydraulic shock absorber of the first aspect of the present invention, when the disc valve is lifted from the seat portion when the valve is opened, the disc valve moves from the portion away from the convex portion having a small set load toward the vicinity of the convex portion having a large set load. Since the valve is gradually lifted, it is possible to suppress a sudden change in the pressure of the oil liquid due to the valve opening, and to prevent the generation of noise and a sudden change in the damping force.
According to the hydraulic shock absorber according to the invention of claim 2, the disc valve is gradually lifted from the portion orthogonal to the diametrical direction in which the convex portion is arranged toward the portion in which the convex portion is arranged to open the valve. To do.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, the hydraulic shock absorber 1 according to the present embodiment is a double-tube hydraulic shock absorber, and an outer cylinder 3 is provided on the outer periphery of the cylinder 2, and the cylinder 2, the outer cylinder 3, A double cylinder structure in which a reservoir 4 is formed between the two is formed. A piston 5 is slidably fitted in the cylinder 2, and the inside of the cylinder 2 is defined by the piston 5 as two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. One end of a piston rod 6 is connected to the piston 5 by a nut 7, and the other end of the piston rod 6 is connected to a rod guide 8 and an oil seal 9 mounted on the upper ends of the cylinder 2 and the outer cylinder 3. It is inserted and extended to the outside. A base valve 10 that divides the cylinder lower chamber 2B and the reservoir 4 is provided at the lower end of the cylinder 2. Oil fluid is sealed in the cylinder upper and lower chambers 2A and 2B. Oil and gas are enclosed.

  The piston 5 is provided with an extension side oil passage 11 and a contraction side oil passage 12 for communicating between the cylinder upper and lower chambers 2A, 2B. The expansion side and contraction side damping force generation mechanisms 13 and 14 are provided, which are composed of an orifice and a disk valve for controlling the flow of the cylinder and generating a damping force. In addition, the base valve 10 is provided with an extension side oil passage 15 and a contraction side oil passage 16 that allow the cylinder lower chamber 2B and the reservoir 4 to communicate with each other. The extension-side oil passage 15 is provided with a check valve 17 that allows only fluid to flow from the reservoir 4 side to the cylinder lower chamber 2B side, and the contraction-side oil passage 16 has a reservoir from the cylinder lower chamber 2B side. A contraction-side damping force generation mechanism 18 is provided that includes an orifice and a disk valve that provide resistance to the flow of the oil liquid to the four sides.

Next, the extension side damping force generation mechanism 13 which is a main part of the present invention will be described in more detail with reference to FIGS. 1 and 3 to 5.
As shown in FIG. 1, on the end surface of the piston 5 on the cylinder lower chamber 2B side, an annular inner peripheral sheet portion 19 protrudes on the inner peripheral side, and an outer peripheral sheet portion 20 (seat portion) protrudes on the outer peripheral side. A plurality of extension-side oil passages 11 (only one is shown in FIG. 1) are opened between them. The inner peripheral sheet part 19 and the outer peripheral sheet part 20 are disposed concentrically, and the outer peripheral sheet part 20 protrudes slightly higher than the inner peripheral sheet part 19 from the end face of the piston 5. An annular disc valve 21 in which a plurality of discs are stacked is seated on the inner peripheral seat portion 19 and the outer peripheral seat portion 20, and a nut whose inner peripheral portion is screwed to the distal end portion of the piston rod 6. 7 and the spacer 22 and the stopper 23 together with the inner peripheral sheet portion 19.

  Of the discs forming the disc valve 21, an orifice 24A (notch) is provided on the outer periphery of the disc 24 that contacts the inner peripheral seat portion 19 and the outer peripheral seat portion 20, and the orifice 24A provides an extension side oil. The passage 11 is always in communication with the cylinder lower chamber 2B. As shown in FIGS. 3 and 4, two convex portions 25 </ b> A protrude from one end face of the disc 25 disposed in the middle portion of the disc forming the disc valve 21 at both ends in the diametrical direction. . The two convex portions 25A are in contact with the adjacent disk on the outer peripheral sheet portion 20 side, and the disc 25 on which the convex portion 25A is formed by the convex portion 25A and the disc overlapped on the back side of the convex portion 25A are the stopper 23 side. Is bent. Thus, a set load in the valve closing direction is applied to the disc 24 seated on the outer peripheral seat portion 20 via the convex portion 25A. The convex portion 25A of the disk 25 can be easily formed by, for example, press molding.

The operation of the present embodiment configured as described above will be described next.
During the extension stroke of the piston rod 6, as the piston 5 in the cylinder 2 slides, the oil in the cylinder upper chamber 2A flows to the cylinder lower chamber 2B through the extension-side oil passage 11 of the piston 5, and the extension-side damping force. A damping force is generated by the generation mechanism 13. At this time, the oil liquid corresponding to the withdrawal of the piston rod 6 from the cylinder 2 opens the check valve 17 of the base valve 10 from the reservoir 4 and flows into the cylinder lower chamber 2B, and the gas in the reservoir 4 expands, thereby Compensate for volume changes in 2.

  During the contraction stroke, as the piston 5 in the cylinder 2 slides, the oil in the cylinder lower chamber 2B flows into the cylinder upper chamber 2A through the contraction-side oil passage 12 of the piston 5, and the contraction-side damping force generation mechanism 14 A damping force is generated by the flow resistance, and when the piston rod 6 enters the cylinder 2, the oil in the cylinder lower chamber 2B flows into the reservoir 4 through the contraction-side oil passage 16 of the base valve 10, and contracts. A damping force is generated by the flow resistance of the side damping force generation mechanism 18, and the sum of these damping forces becomes the damping force during the contraction stroke. At this time, the gas in the reservoir 4 is compressed as much as the piston rod 6 enters the cylinder 2 to compensate for the volume change in the cylinder.

Next, the operation of the extension side damping force generation mechanism 13 which is a main part of the present invention will be described in more detail.
During the extension stroke of the piston rod 6, in the low piston speed range, the oil liquid flows from the extension side oil passage 11 through the orifice 24 </ b> A to the cylinder lower chamber 2 </ b> B, thereby generating a damping force having an orifice characteristic. When the piston speed increases and the pressure on the cylinder upper chamber 2A side reaches the valve opening pressure of the disk valve 21, the disk valve 21 opens, and a damping force of the valve characteristic is generated to cause an excessive increase of the damping force. Suppress.

  Here, since the set load is applied to the disc 24 seated on the outer peripheral seat portion 20 by the convex portion 25A of the disc 25, the set load is large in the vicinity of the convex portion 25A, and the set load increases as the distance from the convex portion 25A increases. Is getting smaller. For this reason, when the disc valve 21 is opened, the disc 24 seated on the outer peripheral seat portion 20 has an outer peripheral portion (a portion perpendicular to the diametrical direction where the convex portion 25A is disposed) first away from the convex portion 25A. The sheet is lifted from the sheet part 20 and is sequentially lifted from the outer sheet part 20 toward the convex part 25A. As a result, the disc valve 21 is gradually opened without being opened at once, and therefore, sudden fluctuations in the pressure of the oil liquid are alleviated. As shown in FIG. The damping force can be changed smoothly. As a result, the generation of noise can be prevented and the riding comfort of the vehicle can be improved.

  In the above embodiment, as shown in FIG. 5, two or more convex portions 25A of the disk 25 can be arranged at both ends in the diameter direction of the disk 25, and the number of the convex portions 25A The distribution of the set load of the disc valve 21 can be adjusted as appropriate depending on the arrangement. Further, as shown in FIGS. 6 to 8, the convex portion 25A may be formed as an arc-shaped projection.

  Furthermore, although the said embodiment demonstrated the case where this invention was applied to the expansion side damping force generation mechanism 13 of piston 5 as an example, this invention is not restricted to this, The compression side damping force generation | occurrence | production of piston 5 is generated. The present invention can be similarly applied to the mechanism 14, the contraction side damping force generation mechanism 18 of the base valve 10, and other damping force generation mechanisms using other disk valves. Moreover, although the said embodiment demonstrated what clamped the inner peripheral side of the disk valve 21, this invention is applied similarly to what clamps the outer peripheral side of a disk valve, and lifts the inner peripheral side. Can do.

It is a longitudinal cross-sectional view which expands and shows the principal part of the hydraulic shock absorber which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the hydraulic shock absorber shown in FIG. FIG. 2 is an enlarged plan view of a disk having a convex portion of the hydraulic shock absorber shown in FIG. 1. FIG. 4 is a side view of the disc valve shown in FIG. 3. It is an enlarged plan view of the disc which has a convex part concerning other embodiments of the present invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the hydraulic shock absorber which concerns on further another embodiment of this invention. It is an enlarged plan view of the disk which has the convex part of the hydraulic shock absorber shown in FIG. It is a longitudinal cross-sectional view of the disk shown in FIG. It is a graph which shows the damping force characteristic of the hydraulic shock absorber shown in FIG. It is a graph which shows the damping force characteristic of the conventional hydraulic shock absorber.

Explanation of symbols

1 Hydraulic shock absorber, 2 cylinder, 5 piston, 21 disc valve, 24 disc, 25 disc, 25A convex portion, 20 outer peripheral seat portion (seat portion),

Claims (2)

A cylinder in which oil is sealed, a piston that is slidably fitted in the cylinder, and a disc valve that generates a damping force by controlling the flow of oil caused by sliding of the piston in the cylinder In the hydraulic shock absorber with
The disc valve includes an annular seat portion and a plurality of stacked discs seated on the seat portion, and a convex portion is formed on a part of the plurality of discs to press the disc valve against the seat portion. The hydraulic shock absorber according to claim 1, wherein a set load is large in the vicinity of the convex portion and is small in a portion away from the convex portion. 2. The hydraulic shock absorber according to claim 1, wherein the convex portions are disposed at both ends of the disk in a diametrical direction.

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