JP2007120726A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber which can improve the riding comfort and the driveability of a vehicle by suppressing the sudden change of its damping force characteristic. <P>SOLUTION: A piston 3 connected with a piston rod is fitted in a cylinder filled with working fluid. The piston 3 is provided with a plurality of elongating side oil passages 6 and seat portions 14. Valve body portions 23 formed on the tip end portions of arm portions 22A to 22E of a special shape disk valve 16, the arm portions radially elongating and having different widths, are brought into contact with the respective seats 14. In the low speed range of the piston speed, the damping force of an orifice characteristic is generated by an orifice. In the high speed range of the piston speed, the damping force of a valve characteristic is generated by opening the valve body portions 23. Because the valve body portions 23 are successively opened in order of the width of the arm portions 22A to 22E, the sudden change of the damping force characteristic due to the sudden enlargement of the oil passages can be suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydraulic shock absorber attached to a suspension device or the like of an automobile.

An example of a conventional cylindrical hydraulic shock absorber mounted on the suspension device of an automobile will be described with reference to FIGS. 15 and 16.
As shown in FIG. 15, the hydraulic shock absorber 1 is configured such that a piston 3 is slidably fitted in a cylinder 2 in which oil is sealed, and the inside of the cylinder 2 is separated from the cylinder upper chamber 2 </ b> A and the cylinder bottom by the piston 3. It is divided into two rooms with room 2B. One end of a piston rod 4 is connected to the piston 3 with a nut 5, and the other end of the piston rod 4 is connected to a rod guide (not shown) and an oil seal (not shown) attached to the upper end of the cylinder 2. (Not shown) and extended to the outside. The cylinder lower chamber 2B is connected via a base valve (not shown) to a reservoir (not shown) in which oil and gas are sealed.

  The piston 3 is provided with an extension side oil passage 6 and a contraction side oil passage 7 for communicating between the cylinder upper and lower chambers 2A, 2B. There are provided expansion side and contraction side damping force generation mechanisms 8 and 9, which are composed of an orifice and a disk valve for controlling the flow of the gas and generating a damping force.

  With this configuration, during the extension stroke of the piston rod 4, as the piston 3 in the cylinder 2 slides, the fluid in the cylinder upper chamber 2A flows through the extension-side oil passage 6 of the piston 3 to the cylinder lower chamber 2B. A damping force is generated by the extension side damping force generation mechanism 8. At this time, the oil liquid corresponding to the withdrawal of the piston rod 4 from the cylinder 2 flows from the reservoir to the cylinder lower chamber 2B through the base valve, and the gas in the reservoir 4 expands to compensate for the volume change in the cylinder 2. To do.

  During the contraction stroke, as the piston 3 slides in the cylinder 2, the oil in the cylinder lower chamber 2 </ b> B flows into the cylinder upper chamber 2 </ b> A through the contraction side oil passage 7 of the piston 3, and the contraction side damping force generation mechanism 9 A damping force is generated by the flow resistance. At this time, the gas in the reservoir is compressed as much as the piston rod 4 enters the cylinder 2 to compensate for the volume change in the cylinder.

Next, the damping force characteristic of the hydraulic shock absorber 1 will be described taking the extension side damping force generation mechanism 8 as an example.
On the end surface of the piston 3 on the cylinder lower chamber 2B side, an annular boss portion 10 protrudes from the inner peripheral portion, and an annular seat portion 11 protrudes from the outer peripheral portion. A plurality of extension side oil passages 6 are opened between the boss portion 10 and the seat portion 11 (see FIG. 16). A plurality of stacked disc-shaped disk valves 12 are clamped by the boss portion 10 and the nut 5, and the outer peripheral portion is seated on the seat portion 11. An orifice 13 (notch) is formed in the outer peripheral portion of the disc valve 12 seated on the seat portion 11.

  With this configuration, in the low speed region of the piston speed, the fluid on the cylinder upper chamber 2A side flows through the orifice 13 to the cylinder lower chamber 2B side, so that the damping force of the orifice characteristic that is substantially proportional to the square of the piston speed. (Refer to the broken line in region A in FIG. 14). In the high speed region of the piston speed, the pressure of the oil liquid on the cylinder upper chamber 2A side increases due to the increase in the flow resistance of the orifice 13, reaches the valve opening pressure of the disk valve 12, and the disk valve 12 bends to open the valve. As a result, the flow path of the oil liquid is expanded, and a damping force having a valve characteristic substantially proportional to the piston speed is generated (see the broken line in the region B in FIG. 14). As a result, an appropriate damping force can be generated in the low speed region of the piston speed, and an excessive increase in the damping force can be suppressed in the high speed region of the piston speed, thereby improving the riding comfort and steering stability of the vehicle. be able to.

As described above, for example, Patent Document 1 discloses a hydraulic shock absorber that generates a damping force by controlling a flow of oil generated by sliding a piston in a cylinder by a damping force generation mechanism including an orifice and a disk valve. Are listed.
JP 2004-125023 A

  However, the conventional hydraulic shock absorber has the following problems. When the orifice characteristic (area A in FIG. 14) shifts to the valve characteristic (area B in FIG. 14), that is, the pressure of the oil on the cylinder upper chamber 2A side rises, and the disk valve 12 bends and opens. When the valve is operated, the entire circumference is lifted from the annular seat portion 11, so that the flow path of the oil liquid suddenly expands, and a sudden pressure fluctuation occurs and the damping force characteristic changes rapidly (FIG. 14). (See valve opening point P in the middle). This sudden change in the damping force characteristic adversely affects the ride comfort and handling stability of the vehicle.

  The present invention has been made in view of the above points, and an object thereof is to provide a hydraulic shock absorber capable of suppressing a rapid change in damping force characteristics.

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, one end connected to the piston, and the like. A piston rod whose end extends to the outside of the cylinder, an oil passage through which oil liquid flows by sliding of the piston in the cylinder, a valve seat provided on the downstream side of the oil passage, and the valve seat In a hydraulic shock absorber provided with a disk valve that sits on and off and controls the flow of oil in the oil passage to generate a damping force,
A plurality of the oil passages and the valve seats are arranged, and the disc valve is seated on the plurality of valve seats so that the valve opening pressure is different with respect to each valve seat.
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 disc valve has portions having different rigidity.
The hydraulic shock absorber according to a third aspect of the present invention is characterized in that, in the configuration of the first aspect, the disk valve has a different valve opening pressure with respect to each valve seat by a retainer contacting the back surface thereof.
The hydraulic shock absorber according to a fourth aspect of the present invention is characterized in that, in the configuration of the first aspect, the disk valve has a different valve opening pressure depending on the arrangement of the valve seat with respect to the disk valve.

According to the hydraulic shock absorber according to the first aspect of the present invention, the disc valve is sequentially opened from the valve seat having a low valve opening pressure to the valve seat having a high valve opening pressure, so that rapid expansion of the flow path due to the valve opening is suppressed. be able to.
According to the hydraulic shock absorber according to the second aspect of the present invention, in the disk valve, the valve opening pressure in the portion with high rigidity becomes high, and the valve opening pressure in the portion with low rigidity becomes low.
According to the hydraulic shock absorber pertaining to the invention of claim 3, the valve opening pressure for each valve seat of the disc valve is adjusted by the retainer.
According to the hydraulic shock absorber pertaining to the invention of claim 4, the valve opening pressure for each valve seat is adjusted by the arrangement of the valve seat.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, only the piston part, which is the main part of the hydraulic shock absorber according to the present embodiment, is illustrated, and the same reference numerals are used for the same parts as in the conventional example shown in FIGS. 15 and 16. Only the different parts will be described in detail.

A first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
As shown in FIGS. 1 to 3, in the hydraulic shock absorber according to the present embodiment, the piston 3 is provided with a plurality (5 in the illustrated example) of extension side oil passages 6 (oil passages), On the end surface of the piston 3 on the cylinder lower chamber 2 </ b> B side, openings of a plurality of extension-side oil passages 6 are arranged at equal intervals in the circumferential direction at substantially the center in the radial direction. And the annular seat part 14 (valve seat) protrudes around each opening part of the some extending | stretching side oil path 6. As shown in FIG. An annular boss 15 projects from the inner peripheral portion of the piston 3, and a plurality of contraction-side oil passages 7 are opened at the outer peripheral portion.

  Between the boss portion 15 and the nut 5, there are a deformed disk valve 16 (disk valve), a disk-shaped disk valve 17, retainers 20 and 21 whose outer diameter is smaller than that of the disk valve 17, and a spacer 19 made of a thick washer. The inner periphery of the is clamped. The deformed disk valve 16 includes arm portions 22A to 22E that extend radially toward the openings of the plurality of extension-side oil passages 6, and a disc-shaped valve body portion 23 formed at the tip of each arm portion 22A to 22E. The valve main body portion 23 is seated on the seat portion 14 projecting around each opening portion of the plurality of extension-side oil passages 6, respectively. The arm portions 22 </ b> A to 22 </ b> E of the deformed disc valve 16 have different widths and different rigidity, and are adjusted so that the valve opening pressures of the valve body portions 23 with respect to the seat portions 14 are different.

  The spacer 19 interposed between the deformed disc valve 16 and the boss portion 15 adjusts the initial deflection (set load) of the deformed disc valve 16, and the height in the axial direction in a state of being overlapped with the boss portion 15. However, it is lower than the sheet part 14 (in FIG. 3, the lower surface of the spacer 19 is located above the lower end of the sheet part 14). A gap is formed between the deformed disk valve 16 and the disk valve 17 by the retainer 20, and after the deformed disk valve 16 is bent and abuts against the disk valve 17, the spring force of the disk valve 17 is changed to the deformed disk. It acts in the valve closing direction of the valve 16. The stopper 18 limits the amount of bending of the disc valve 17 by contacting the stopper 18 with the disc valve 17 being bent by the gap of the retainer 21.

  The piston 3 is provided with an orifice (not shown) for constantly communicating between the cylinder upper and lower chambers 2A and 2B to generate a damping force having an orifice characteristic. This orifice can be formed, for example, by providing a notch in the compression side damping force generation mechanism 9 (see FIG. 15). A positioning pin 24 for positioning the deformed disk valve 16 projects from the end surface of the piston 3 on the cylinder lower chamber 2B side.

Next, the operation of the present embodiment configured as described above will be described.
When the pressure of the oil liquid on the cylinder upper chamber 2A side reaches the valve opening pressure of the deformed disk valve 16 during the extension stroke of the piston rod 4, the arm portions 22A to 22E are bent and the valve body portion 23 is lifted from the seat portion 14. Open the valve. At this time, since the valve opening pressures of the valve main body portion 23 are different depending on the arm portions 22A to 22E having different widths (rigidities), the valve body portion 23 is sequentially opened from a low valve opening pressure to a high valve opening pressure. As a result, the flow path of the oil liquid can be gradually expanded, so that a sudden change in the damping force characteristic due to the rapid expansion of the flow path can be prevented, and the riding comfort and steering stability of the vehicle can be improved. it can.

  After the valve main body portion 23 comes into contact with the disc valve 17, the opening degree of the valve main body portion 23 is adjusted by the spring force of the disc valve 17, and a damping force approximately proportional to the piston speed is generated. Further, by restricting the amount of deflection of the disc valve 17 by the stopper 18, the deformed disc valve 16 and the disc valve 17 are prevented from being damaged.

The extension side damping force characteristic of the hydraulic shock absorber according to the present embodiment is shown by a solid line in FIG. The deformed disc valve 16 is opened from the orifice characteristic (region A in FIG. 14) to shift to the deformed valve property (region B ′ in FIG. 14), and the valve main body portion 23 is formed by the arm portions 22A to 22E having different widths (rigidities). Will gradually open and gradually expand the flow path of the oil liquid, so that sudden changes in damping force characteristics due to rapid expansion of the flow path can be prevented, and the ride comfort and handling stability of the vehicle are improved. be able to.
Then, the deformed disc valve 16 comes into contact with the disc valve 17 and the disc valve 17 starts to open (opening point P ′ in FIG. 14). Thereafter, the valve characteristic is proportional to the piston speed as in the prior art.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the following description, the same reference numerals are given to the same parts with respect to the first embodiment, and only different parts will be described in detail.

  As shown in FIGS. 4 and 5, in the hydraulic shock absorber according to the present embodiment, the inner peripheral portion is clamped by the boss portion 15 and the nut 5 on the seat portion 14 around the plurality of extension side oil passages 6. The outer periphery of the disc-shaped disc valve 25 is seated. A disc-shaped retainer 26 (retainer) is laminated on the disc valve 25, and a retainer 20, a disc valve 17 and a retainer 21 are further laminated.

  The deformed retainer 26 has an inner peripheral portion clamped by the boss portion 15 and the nut 5, and has arm portions 26 </ b> A to 26 </ b> E that extend radially toward the openings of the plurality of extension-side oil passages 6. The arm portions 26 </ b> A to 26 </ b> E have different widths and radial lengths, abut against the back side of the disc valve 25, change the flexural rigidity of each portion of the disc valve 25, and thereby a plurality of extension side oils. The valve opening pressures for the respective seat portions 14 of the passage 6 are adjusted to be different.

  With this configuration, when the pressure of the oil liquid on the cylinder upper chamber 2A side reaches the valve opening pressure of the disk valve 25 during the extension stroke of the piston rod 4, the arm portions 26 </ b> A to 26 </ b> A of the deformed retainer 26 together with the disk valve 25. 26E is bent and the disk valve 25 is lifted from the seat portion 14 and opened. At this time, since the bending rigidity of each part of the disk valve 25 differs depending on the arm parts 26A to 26E, the disk valve 25 is bent and opened sequentially from a part with low rigidity to a part with high rigidity. Thereby, the flow path of an oil liquid can be expanded gradually and the effect | action and effect similar to the said 1st Embodiment can be show | played.

  Next, a third embodiment of the present invention will be described with reference to FIGS. In the following description, the same reference numerals are given to the same parts with respect to the second embodiment, and only different parts will be described in detail.

  As shown in FIGS. 6 and 7, in the hydraulic shock absorber according to the present embodiment, an irregular disk 27 (retainer) is laminated on the disk valve 25 instead of the irregular retainer 26 of the second embodiment. . The deformed disk 27 is a disk-shaped member provided with a notch 27A. By changing the bending rigidity of the disk valve 25 by the notch 27A, the valve opening pressure for each seat portion 14 of the extension side oil passage 6 is changed. Have to be different.

  As a result, the disc valve 25 is sequentially opened from the portion where the valve opening pressure is low, that is, from the position facing the notch 27A to the high portion when the disc valve 25 is opened. As a result, the flow path of the oil liquid can be gradually enlarged, and the same operations and effects as in the second embodiment can be achieved.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the following description, the same reference numerals are given to the same parts with respect to the third embodiment, and only different parts will be described in detail.

  As shown in FIGS. 8 and 9, in the hydraulic shock absorber according to the present embodiment, the seat portions 14 around the openings of the plurality of extension-side oil passages 6 are arranged at different positions in the radial direction. Further, a plurality of disk-like disc valves 25 (the disc 17 is the same disc as the disc 25) are stacked instead of the deformed disc 27 and the retainer 20.

  As a result, the portion of the disk valve 25 seated on the seat portion 14A of the extension side oil passage 6A arranged on the radially outer side is easy to bend and the valve opening pressure is low, and the extension side oil passage 6B arranged on the radially inner side. The portion of the disc valve 25 seated on the seat portion 14B is difficult to bend and the valve opening pressure is high. As a result, when the valve valve 25 is opened, the disk valve 25 is sequentially opened from a portion where the valve opening pressure is low to a portion where the valve opening pressure is high, and the flow path of the oil liquid can be gradually expanded. The same operations and effects can be achieved.

  Next, a fifth embodiment of the present invention will be described with reference to FIGS. In the following description, the same reference numerals are given to the same parts with respect to the third embodiment, and only different parts will be described in detail.

  As shown in FIGS. 10 to 13, in the hydraulic shock absorber according to the present embodiment, a retainer 20 and a pressing disk 28 are laminated instead of the deformed disk 27 of the third embodiment. The pressing disk 28 is a disk-shaped member, and has a plurality of protrusions 28 </ b> A that come into contact with the back surface of the disk valve 25. The protrusions 28A are unevenly distributed, and by pressing the disc valve 25 in the valve closing direction, the valve opening pressure of the disc valve 25 with respect to the respective seat portions 14 of the plurality of extension side oil passages 6 is made different. Yes. In this case, the valve opening pressure of each part of the disk valve 25 can be adjusted by the position, number, height, and area of the protrusion 28A.

As a result, the disc valve 25 is opened sequentially from a portion where the valve opening pressure is low to a portion where the valve opening pressure is high. As a result, the flow path of the oil liquid can be gradually expanded, and the same operations and effects as the third embodiment can be achieved.
The protrusion 28A of the pressing disk 28 may protrude toward the disk valve 25, and the retainer 20 may be provided between the pressing disk 28 and the disk valve 17.
Further, the retainer 20 is not always necessary, and the retainer 20 may be eliminated by strongly tightening the nut 5 so that the inner periphery of the pressing disk 28 and the disk valve 17 is bent toward the piston side.

  In the first to fifth embodiments, the extension side damping force generation mechanism has been described as an example. However, the present invention is not limited to this and can be similarly applied to the contraction side damping force generation mechanism.

It is a top view of the piston which is the principal part of the hydraulic shock absorber concerning a 1st embodiment of the present invention, and an extension side damping force generation mechanism. It is a longitudinal cross-sectional view of the piston and the extension side damping force generation mechanism shown in FIG. FIG. 3 is an enlarged vertical sectional view of the damping force generation mechanism shown in FIG. 2. It is a top view of the piston which is a principal part of the hydraulic shock absorber concerning a 2nd embodiment of the present invention, and an extension side damping force generation mechanism. FIG. 5 is an enlarged longitudinal sectional view of the damping force generation mechanism shown in FIG. 4. It is a top view of the piston which is a principal part of the hydraulic shock absorber concerning a 3rd embodiment of the present invention, and an extension side damping force generation mechanism. FIG. 7 is an enlarged vertical sectional view of the damping force generation mechanism shown in FIG. 6. It is a top view of the piston which is a principal part of the hydraulic shock absorber concerning a 4th embodiment of the present invention, and an extension side damping force generation mechanism. FIG. 9 is an enlarged longitudinal sectional view of the damping force generation mechanism shown in FIG. 8. It is a top view of the piston which is the principal part of the hydraulic shock absorber concerning a 5th embodiment of the present invention, and an extension side damping force generation mechanism. It is a top view of the press disk of the hydraulic shock absorber shown in FIG. It is a longitudinal cross-sectional view of the press disk shown in FIG. It is an enlarged vertical sectional view of the damping force generation mechanism shown in FIG. It is a graph which shows the damping force characteristic of the hydraulic shock absorber concerning one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the principal part of the conventional cylindrical hydraulic shock absorber. FIG. 16 is a plan view of the piston and the extension side damping force generation mechanism of the hydraulic shock absorber shown in FIG. 15.

Explanation of symbols

2 cylinder, 3 piston, 4 piston rod, 6 extension side oil passage (oil passage), 14 seat part (valve seat), 16 deformed disc valve (disc valve)

Claims (4)

A cylinder filled with oil, a piston slidably fitted in the cylinder, a piston rod having one end connected to the piston and the other end extending outside the cylinder, and the cylinder An oil passage through which oil liquid circulates by sliding of an inner piston, a valve seat provided on the downstream side of the oil passage, and a seat on and off the valve seat to control the flow of the oil liquid in the oil passage. In a hydraulic shock absorber with a disc valve that generates a damping force,
A hydraulic shock absorber, wherein a plurality of the oil passages and the valve seats are arranged, and the disk valves are seated on the plurality of valve seats so that the valve opening pressures differ from each other. The hydraulic shock absorber according to claim 1, wherein the disc valve has portions having different rigidity. 2. The hydraulic shock absorber according to claim 1, wherein the disk valve has different valve opening pressures with respect to the valve seats depending on a retainer that contacts the back surface of the disk valve. 2. The hydraulic shock absorber according to claim 1, wherein a valve opening pressure of the disk valve varies depending on an arrangement of the valve seat with respect to the disk valve.

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