JP2010054009A - Shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber with a coil spring improved in assembling efficiency by increasing the damping force of the coil spring to thrust a disc valve without increasing the spring force thereof. <P>SOLUTION: Into a cylinder 2 filled with oil liquid, a piston 3 is inserted to which a piston rod 4 is connected. Damping force generating mechanisms D1, D2 are provided in elongation and contraction side oil paths 9, 10 of the piston 3 for generating damping force. The damping force generating mechanisms D1, D2 thrust discs 15, 22 on outside seat portions 11, 18 and inside seat portions 12, 19 with valve springs 17, 24 to adjust the valve opening pressure thereof. The inside seat portions 12, 19 are arranged near the outside seat portions 11, 18 to encircle opening portions 9A, 10A of the elongation and contraction side oil paths 9, 10. Thus, the pressure receiving areas of the discs 15, 22 are reduced to generate greater damping force without increasing the spring force of the valve springs 17, 24. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a shock absorber that uses fluid pressure.

  In general, a cylindrical hydraulic shock absorber attached to a suspension device of a vehicle such as an automobile has a piston in which a piston rod is connected in a cylinder in which oil is sealed, and is slidable. It has a structure provided with a damping force generation mechanism including an orifice, a disk valve, and the like. Thereby, the flow of the oil liquid generated by the sliding of the piston in the cylinder accompanying the expansion and contraction of the piston rod is controlled by the orifice and the disk valve to generate a damping force.

  In the low piston speed range, the orifice generates a damping force having an orifice characteristic (the damping force is approximately proportional to the square of the piston speed), and in the high piston speed range, the disk valve bends and opens. Thus, a damping force having a valve characteristic (a damping force is approximately proportional to the piston speed) is generated.

Further, as described in Patent Document 1, for example, a hydraulic shock absorber is known in which a disk valve is pressed against a seat portion by a coil spring and the valve opening characteristics of the disk valve are adjusted by the spring force of the coil spring. Yes.
JP-A-9-291196

  However, in the case where the disk valve is pressed by a coil spring like the one described in Patent Document 1, there are the following problems. Although the damping force can be increased by increasing the spring force of the coil spring, in this case, a large compressive force is required when assembling the coil spring, so that the assembling property is lowered.

  An object of the present invention is to provide a shock absorber capable of generating a large damping force without increasing the spring force of a coil spring that presses a disk valve.

In order to solve the above-described problems, the present invention provides a cylinder in which a fluid is sealed, a piston slidably inserted into the cylinder, and is connected to the piston and extends from the cylinder to the outside. In a shock absorber including a piston rod, a flow path that generates a flow of fluid by sliding of the piston, and a damping force generation mechanism having a disk provided in the flow path.
The damping force generation mechanism includes a valve body provided with an opening of the flow path, an annular outer sheet part provided on the valve body and projecting from an outer periphery of the opening of the flow path, and the outer sheet part. An inner sheet portion that is disposed in the vicinity of the inner peripheral portion and protrudes so as to surround the opening of the flow path between the outer sheet portion, and a disk that is seated on the outer sheet portion and the inner sheet portion. And a coil spring that presses the disk toward the inner sheet portion.

  According to the shock absorber according to the present invention, a large damping force can be generated without increasing the spring force of the coil spring that presses the disk.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a piston portion as a valve body which is a main part of the shock absorber according to this embodiment, and FIG. 2 shows a lower end surface of the piston. As shown in FIG. 1, a shock absorber 1 is a cylindrical hydraulic shock absorber installed in a suspension device of an automobile, and is a cylinder 2 (in FIG. The piston 3 is slidably inserted into the inside of the cylinder 2 and the inside of the cylinder 2 is divided into two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. One end of a piston rod 4 is connected to the piston 3, and the other end of the piston rod 4 is an oil seal (not shown) for sealing the end of the cylinder 2 and a rod guide (not shown) for guiding the piston rod 4. (Not shown) is inserted, penetrated and extended to the outside.

  A gas chamber is formed on the other end side of the cylinder 2 by a free piston (not shown), and the inside of the cylinder 2 accompanying the stroke of the piston rod by the compression and expansion of the high-pressure gas enclosed in the gas chamber. The volume change is allowed. Instead of forming the gas chamber, a reservoir filled with oil and gas may be connected to the cylinder lower chamber 2B so as to allow a change in volume in the cylinder 2.

  The piston 3 has a structure that is divided into two in the axial direction composed of the piston halves 3A and 3B. Then, the piston halves 3A and 3B are coupled to each other, a substantially cylindrical spring receiver 6 is brought into contact with the one piston half 3A, and a small-diameter portion 4A formed at one end of the piston rod 4 is attached thereto. The piston 3 and the spring receivers 6 and 7 are integrated and connected to the piston rod 4 by inserting and penetrating and screwing a substantially cylindrical spring receiver 7 to the tip of the small diameter portion 4A. A piston band 8 that is a sliding member is attached to the outer peripheral portion of the piston 3.

  The piston 3 is provided with an extension-side oil passage 9 and a contraction-side oil passage 10 that communicate between the cylinder upper and lower chambers 2A, 2B and serve as a flow passage for the oil liquid. The extension-side oil passage 9 has a circular opening 9A at the substantially radial center of the end surface of the piston 3 on the cylinder lower chamber 2B side. Five openings 9A are arranged at equal intervals along the circumferential direction. The extension-side oil passage 9 has a rectangular opening 9B on the outer peripheral portion of the end surface of the piston 3 on the cylinder upper chamber 2A side. Five openings 9B are arranged in the same phase as the opening 9A on the opposite side at equal intervals along the circumferential direction. In addition, although the number of openings 9A and 9B of the extension side oil passage 9 is five in the illustrated example, the number is arbitrary.

  The contraction-side oil passage 10 has a circular opening 10A at the substantially radial center of the end surface of the piston 3 on the cylinder upper chamber 2A side, like the contraction-side oil passage 9. Five openings 10A are arranged at equal intervals along the circumferential direction. Further, a rectangular opening 10B is provided on the outer peripheral portion of the end surface of the piston 3 on the cylinder lower chamber 2B side. Five openings 10B are arranged in the same phase as the opening 10A on the opposite side at equal intervals along the circumferential direction. In addition, although the number of openings 10A and 10B of the contraction side oil passage 10 is five in the illustrated example, the number thereof is arbitrary. The openings 10A and 10B of the contraction side oil passage 10 are disposed between the openings 9B and 9A of the extension side oil passage 9, respectively.

Damping force generation mechanisms D1 and D2 are provided for controlling the flow of the oil liquid in the extension side oil passage 9 and the contraction side oil passage 10 to generate a damping force.
Next, the damping force generation mechanism D1 of the extension side oil passage 9 will be described. As shown in FIG. 2, the end surface of the piston 3 on the cylinder lower chamber 2 </ b> B side is annular on the inner peripheral side of the opening 10 </ b> B of the contraction side oil passage 10 and around the five openings 9 </ b> A of the extension side oil passage 9. The outer sheet portion 11 protrudes. Further, an annular inner sheet portion 12 protrudes in the vicinity of the inner peripheral portion of the outer sheet portion 11, and an annular groove 13 communicating with the opening 9 </ b> A is formed between the outer sheet portion 11 and the inner sheet portion 12. Yes. The outer peripheral portion of the inner sheet portion 12 is positioned so as to overlap the opening portion 9A, and a substantially circular notch 12A surrounding each opening portion 9A is formed on the outer peripheral portion of the inner sheet portion 12. Thus, the inner sheet portion 12 surrounds the opening 9 </ b> A with the outer sheet portion 11. Further, the inner sheet portion 12 is in a position overlapping the opening portion 9A, is opposed to the large diameter portion facing the outer sheet portion 11 and the innermost peripheral point located on the innermost periphery of the opening portion 9A, and is formed in the notch 12A. There is a small diameter portion that is the smallest diameter. A cylindrical guide portion 14 into which the small diameter portion 4A of the piston rod 4 is inserted protrudes from the center portion of the end surface of the piston 3 on the cylinder lower chamber 2B side.

  Single or multiple stacked disk-shaped discs 15 are seated on the outer seat portion 11 and the inner seat portion 12 of the piston 3. The disk 15 has an opening into which the guide portion 14 of the piston 3 is inserted in the center portion, and is guided by the guide portion 14 so as to be slidable in the axial direction. A cylindrical movable spring receiver 16 having a flange portion 16A on the outer periphery of one end is fitted to the guide portion 14 and guided by the guide portion 14 so as to be slidable in the axial direction, and the flange portion 16A comes into contact with the disk 15. ing. A flange portion 7A is formed on the outer periphery of one end of the spring receiver 7 screwed to the small diameter portion 4A of the piston rod 4, and a valve spring 17 is interposed between the flange portion 7A and the flange portion 16A of the movable spring receiver 16. It is intervened. The valve spring 17 is a compression coil spring, and presses the disk 15 against the outer seat portion 11 and the inner seat portion 12 with a predetermined set load. A notch-shaped orifice 15A that allows the annular groove 13 and the cylinder lower chamber 2B to always communicate with each other is formed on the outer peripheral portion of the disk 15 seated on the outer seat portion 11.

  Next, the damping force generation mechanism D2 of the compression side oil passage 10 will be described. On the end surface of the piston 3 on the cylinder lower chamber 2B side, five openings of the contraction-side oil passage 10 are formed on the inner peripheral side of the opening 9B of the extension-side oil passage 10 on the end surface on the cylinder upper chamber 2A side. An annular outer sheet portion 18 protrudes around the portion 10A. Further, an annular inner sheet portion 19 is projected near the inner peripheral portion of the outer sheet portion 18, and an annular groove 20 communicating with the opening 10 </ b> A is formed between the outer sheet portion 18 and the inner sheet portion 19. Yes. The outer peripheral portion of the inner sheet portion 19 is positioned so as to overlap the opening portion 10A, and a substantially circular notch 19A surrounding the periphery of each opening portion 10A is formed on the outer peripheral portion of the inner sheet portion 19. Accordingly, the inner sheet portion 19 surrounds the opening 10 </ b> A with the outer sheet portion 18. A cylindrical guide portion 21 into which the small diameter portion 4A of the piston rod 4 is inserted protrudes from the center portion of the end surface of the piston 3 on the cylinder upper chamber 2A side.

  Single or multiple stacked disc-shaped disks 22 are seated on the outer seat portion 11 and the inner seat portion 12 of the piston 3. The disc 22 has an opening into which the guide portion 21 of the piston 3 is inserted at the center, and is guided by the guide portion 21 so as to be slidable in the axial direction. A cylindrical movable spring receiver 23 having a flange portion 23 </ b> A on the outer periphery of one end portion is fitted to the guide portion 21 and guided by the guide portion 21 so as to be slidable in the axial direction. ing. A flange portion 6A is formed on the outer periphery of one end portion of the spring receiver 6 into which the small diameter portion 4A of the piston rod 4 is inserted, and a valve spring 24 is interposed between the flange portion 6A and the flange portion 23A of the movable spring receiver 23. It is disguised. The valve spring 24 is a compression coil spring, and presses the disk 22 against the outer seat portion 18 and the inner seat portion 19 with a predetermined set load. A notch-shaped orifice 22A is formed on the outer peripheral portion of the disk 22 seated on the outer seat portion 18 so that the annular groove 20 and the cylinder upper chamber 2A are always in communication.

Next, the operation of the present embodiment configured as described above will be described.
During the extension stroke of the piston rod 4, the fluid in the cylinder upper chamber 2 </ b> A is pressurized by the sliding of the piston 3 in the cylinder 2, and flows mainly through the extension-side oil passage 9 to the cylinder lower chamber 2 </ b> B. A damping force is generated by the orifice 15A and the disk 15 of the damping force generation mechanism D1. A part of the oil liquid flows through the orifice 22 </ b> A provided in the contraction-side oil passage 10.

  Thereby, in the piston speed low speed region, the orifice 15A, 22A generates a damping force having an orifice characteristic (a damping force is approximately proportional to the square of the piston speed). When the pressure on the cylinder upper chamber 2A rises due to the increase in the piston speed and reaches the valve opening pressure of the disk 15, the disk 15 opens against the spring force of the valve spring 17 and the flow path area increases. A damping force having a valve characteristic (a damping force is approximately proportional to the piston speed) corresponding to the opening degree is generated.

  Further, during the contraction stroke of the piston rod 4, the fluid on the cylinder lower chamber 2 </ b> B side is pressurized by the sliding of the piston 3 in the cylinder 2, mainly through the contraction side oil passage 10 and on the cylinder upper chamber 2 </ b> A side. The damping force is generated by the orifice 22A and the disk 22 of the damping force generation mechanism D2. A part of the oil liquid flows through the orifice 15 </ b> A provided in the extension-side oil passage 9.

  Thereby, in the piston speed low speed region, the orifice 15A, 22A generates a damping force of the orifice characteristic. When the pressure on the cylinder lower chamber 2B increases and reaches the valve opening pressure of the disk 22 due to the increase of the piston speed, the disk 22 is opened against the spring force of the valve spring 24, and the flow path area is expanded. A damping force having a valve characteristic corresponding to the opening degree is generated.

  FIG. 5 shows the damping force characteristics on the expansion side and the contraction side. In FIG. 5, the solid line (1A) indicates the orifice characteristic in the low speed region of the piston speed, and the solid line (1B) indicates the valve characteristic after the piston speed is increased and the disvalves 15 and 22 are opened.

  Since the inner seat portions 12 and 19 are disposed in the vicinity of the outer seat portions 11 and 18, the pressure receiving area where the disks 15 and 22 seated on these receive the fluid pressure is sufficiently small. Without increasing the spring force, the valve opening pressure of the disks 15 and 22 can be increased to increase the damping force in the high speed region of the piston speed. As a result, the valve springs 17 and 24 can be easily compressed, and their assembling properties can be improved.

  Further, by forming the annular grooves 13 and 20 between the outer sheet portions 11 and 18 and the inner sheet portions 12 and 19, the notched orifices 15A and 22A formed on the outer peripheral portions of the disks 15 and 22 are circular. Regardless of the position in the circumferential direction, the annular grooves 13 and 20 always communicate with each other. Therefore, when assembling the disks 15 and 22, positioning in the circumferential direction is unnecessary, and assembling performance is improved. Can be increased.

  Next, a modification of the above embodiment will be described with reference to FIGS. In addition, with respect to the said embodiment, the same code | symbol is attached | subjected to the same part and only a different part is demonstrated in detail.

  FIG. 3 is an enlarged view of the extension-side damping force generation mechanism D1, and as shown in FIG. 3, in this modification, the disk 15 is interposed between the disk 15 and the flange portion 16A of the movable spring receiver 16. A small-diameter retainer 25 that supports 15 inner peripheral portions is interposed. In the same way as for the contraction-side damping force generation mechanism D2, a small-diameter retainer (not shown) is interposed between the disk 22 and the flange portion 23A of the movable spring receiver 23. Further, a step is provided between the outer sheet portion 11 and the inner sheet portion 12, and the axial height of the outer sheet portion 11 is larger than the axial height of the inner sheet portion 12.

  As a result, when the discs 15 and 22 are opened, the discs 15 and 22 are first bent by the retainer 25 as a fulcrum and lifted from the outer seat portions 11 and 18, and then the springs of the valve springs 17 and 24 are increased by the increase in the oil pressure. The flow path is expanded by lifting from the inner sheet portions 12 and 19 against the force. As a result, as shown in FIG. 5, the damping force characteristic becomes the orifice characteristic by the orifices 15A and 22A indicated by the broken line (2A) in the low speed region of the piston speed, and supports the retainer 25 in the intermediate speed region of the piston speed. Due to the deflection of the disks 15 and 22, the valve characteristic (large inclination) indicated by the broken line (2B) is obtained. In the high speed region of the piston speed, the valve characteristic indicated by the broken line (2C) (small inclination) is obtained by compression of the valve springs 17 and 24. It becomes.

  In this case, by changing the outer diameter of the retainer 25, the position of the fulcrum when the disks 15 and 22 are bent changes, so that, as shown in FIG. The damping force characteristic can be changed in the range of broken lines (2B), (2C) to (2B ′), (2C ′). This is because the pressure receiving area is increased by forming a gap between the piston 3 and the disks 15 and 22 at the outer peripheral portion of the outer diameter of the retainer 25 that becomes a fulcrum when the disks 15 and 22 are bent. This is because of a low. Therefore, when the outer diameter of the retainer 25 is the same as the small diameter portion of the inner sheet portion, the characteristics are (2B ′) and (2C ′). When the outer diameter of the retainer is smaller than the small diameter portion, 2B) and (2C).

  In the above-described embodiment, as shown in FIG. 4, the outer peripheral portions of the inner sheet portions 12 and 19 may be integrated with the outer sheet portions 11 and 18, and the annular grooves 13 and 20 may be omitted ( Only the outer sheet part 11, the inner sheet part 12 and the annular groove 13 on the stretch side are shown). In this case, the notched orifices 15A and 22A provided on the outer peripheral portions of the disks 15 and 22 need to communicate with the notches 12A and 19A on the outer peripheral portions of the inner sheet portions 12 and 19 (in FIG. Only the notch 12A of the inner sheet portion 12 on the side is shown), and positioning in the circumferential direction is required when the disks 15 and 22 are assembled.

  In the above embodiment, the disk valve structure according to the present invention is applied to both the expansion side and the contraction side. However, either of them may be a normal disk valve structure. In addition, this disc valve structure is provided in the piston portion, but it can also be provided in a portion that becomes a damping force generating mechanism of the base valve or other oil liquid passage. However, the effect of the present invention can be exerted more on the expansion side that requires more damping force, that is, on the piston portion than on the contraction side, that is, on the base valve. Furthermore, although the said embodiment demonstrated the hydraulic buffer which generate | occur | produces damping force by controlling the flow of an oil liquid, this invention is not limited to this and controls the flow of other fluids, such as gas. Although it can be applied to a shock absorber that generates a damping force, it is more preferable to use an oil liquid from the viewpoint of the stability of the damping force characteristic.

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 bottom view of the piston of the shock absorber shown in FIG. It is a longitudinal cross-sectional view which expands and shows the disk valve part of the expansion | extension side which is the principal part of the modification of the shock absorber shown in FIG. It is a bottom view of the piston of the other modification of the shock absorber shown in FIG. FIG. 4 is a graph showing damping force characteristics of the shock absorber shown in FIGS. 1 to 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Shock absorber, 2 cylinder, 3 piston, 4 piston rod, 9 extension side oil path (flow path), 9A opening part, 11 outer sheet | seat part, 12 inner sheet | seat part, 17 valve spring (coil spring), D1 damping force generation mechanism

Claims (6)

A cylinder filled with fluid; a piston slidably inserted into the cylinder; a piston rod connected to the piston and extending outward from the cylinder; and a fluid flow caused by sliding of the piston In a shock absorber provided with a flow path for generating a damping force generation mechanism having a disk provided in the flow path,
The damping force generation mechanism includes a valve body provided with an opening of the flow path, an annular outer sheet part provided on the valve body and projecting from an outer periphery of the opening of the flow path, and the outer sheet part. An inner sheet portion that is disposed in the vicinity of the inner peripheral portion and protrudes so as to surround the opening of the flow path between the outer sheet portion, and a disk that is seated on the outer sheet portion and the inner sheet portion. And a coil spring that presses the disk toward the inner sheet portion. An annular groove is formed between the outer sheet portion and the inner sheet portion over substantially the entire circumference, and a notch-shaped orifice communicating with the annular groove is provided in the outer circumferential portion of the disk. Item 4. The shock absorber according to item 1. The shock absorber according to claim 1 or 2, wherein a retainer that supports an inner peripheral portion of the disk is interposed between the disk and the coil spring. The shock absorber according to claim 3, wherein an axial height of the outer sheet portion is larger than an axial height of the inner sheet portion. The inner sheet portion has a large diameter portion facing the outer sheet portion and a small diameter portion facing an innermost peripheral point located at the innermost periphery of the opening, and the retainer is the same as the small diameter portion. The shock absorber according to claim 3 or 4, wherein the shock absorber has a diameter. The inner sheet portion has a large diameter portion facing the outer sheet portion and a small diameter portion facing an innermost peripheral point located at the innermost periphery of the opening, and the retainer is more than the small diameter portion. The shock absorber according to claim 3 or 4, wherein the shock absorber has a small diameter.

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