JP5234273B2 - Shock absorber - Google Patents

Description

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

  In general, a cylindrical hydraulic shock absorber attached to a suspension device of a vehicle such as an automobile is provided with a slidable piston having a piston rod connected to a cylinder in which hydraulic fluid is sealed. 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 hydraulic fluid 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 piston speed low speed region, the orifice generates a damping force having an orifice characteristic in which the damping force is approximately proportional to the square of the piston speed. In the piston speed high speed region, the disk valve bends and opens. A damping force having a valve characteristic in which the damping force is approximately proportional to the piston speed is generated. The damping force characteristics of this type of conventional hydraulic shock absorber are shown by broken lines in FIG. In FIG. 10, symbol A indicates a valve opening point of the disc valve. For the low speed region of the piston speed, depending on the orifice area, for the medium speed region after opening the disk valve, for the bending rigidity after opening the disk valve, and for the high speed region, the flow path after opening the disk valve. The damping force characteristic can be set depending on the area.

  In the conventional hydraulic shock absorber, the damping force changes abruptly at the valve opening point A of the disk valve, that is, when the piston speed increases and the orifice characteristic is switched to the valve characteristic. The damping force characteristic may not be desirable.

Therefore, conventionally, for example, Patent Document 1 discloses a technique for suppressing a sudden change in damping force by making the shape of a valve seat of a disc valve non-circular and changing its opening in stages in a hydraulic shock absorber. Is disclosed.
JP-A-2-195039

  Against this background, there is a demand for a shock absorber that can easily set the damping force characteristic while suppressing a sudden change in damping.

  An object of the present invention is to provide a shock absorber that can alleviate a sudden change in damping force and can facilitate the setting of damping force characteristics.

In order to solve the above problems, a shock absorber according to the present invention includes a cylinder in which a working fluid is sealed,
A piston slidably inserted into the cylinder and defining the interior of the cylinder in two chambers;
A piston rod connected to the piston, at least one end of which projects out of the cylinder;
A passage through which the working fluid flows by sliding of the piston;
A damping force generation mechanism that is provided in a part of the passage and controls the flow of the working fluid to generate a damping force;
The damping force generation mechanism is
A valve body through which the passage extends, and
A substantially circular outer sheet projecting so as to surround the plurality of openings of the passage in the valve body;
An inner sheet protruding inside the outer sheet and having a lower protrusion height than the outer sheet;
A disk support portion that protrudes between the outer sheet and the inner sheet, has a protruding height lower than that of the outer sheet, is equal to or greater than the inner sheet, and extends radially between the plurality of openings. ,
A first disk clamped to the inner sheet, seated on the outer sheet, and abutting the disk support;
Characterized in that it comprises a first laminated on the disk, diameter at than the outer diameter of said first disk and second disk outer diameter is arranged such that over said disc support section And

  According to the shock absorber according to the present invention, a sudden change in damping force can be mitigated, and the damping characteristics can be easily set.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
An overall view of the shock absorber according to the present embodiment is shown in FIG. 3, and a piston portion which is a main part thereof is shown in an enlarged manner in FIG. 1. As shown in FIG. 3, the shock absorber 1 according to the present embodiment is a single cylinder type hydraulic shock absorber attached to a suspension device of an automobile, and the main shock absorber 1 is installed in a cylinder 2 in which a working fluid is sealed as a working fluid. A piston 3 that functions as a valve body used in the invention is slidably provided. The piston rod 4 extends outside through a sealing means including a rod guide 6 and an oil seal 7 provided at the end of the cylinder 2, and one end of the piston rod 4 is connected to the vehicle body outside the cylinder 2. . On the other hand, the piston 3 is connected to the other end of the piston rod 4 by a nut 5 inside the cylinder 2. The inside of the cylinder 2 is divided into two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B, by the piston 3. A free piston 8 is slidably provided on the bottom side of the cylinder 2 to form a gas chamber 9, and the cylinder accompanying expansion and contraction of the piston rod 4 due to compression and expansion of high-pressure gas sealed in the gas chamber 9. The volume change of the upper and lower chambers 2A and 2B is allowed.

  As shown in FIG. 1, the piston 3 is divided into a plurality of parts along the axial direction, and has a divided structure divided into two in this embodiment. One of the split structure pistons 3 is a piston half 3A, and the other is a piston half 3B. One and the other passages for communicating between the cylinder upper and lower chambers 2A and 2B are formed in the piston 3 in which the piston halves 3A and 3B are integrally coupled. In the present embodiment, one passage is the extension side passage 10 and the other passage is the contraction side passage 11. The extension side passage 10 has a plurality of openings 10 </ b> A that open to the outer periphery of the upper end surface of the piston 3. In the present embodiment, the openings 10A are substantially the same rectangle as an opening 11A shown in FIG. 2 described later, and five openings are arranged at substantially equal intervals along the circumferential direction. The extension-side passage 10 has a plurality of openings 10B that open to a portion from the center with respect to the opening 10A and an opening 11A of the contraction-side passage 11 described later on the lower end surface of the piston 3. As shown in FIG. 2, in the present embodiment, the openings 10 </ b> B are circular, and five openings are arranged at substantially equal intervals along the circumferential direction.

  Further, the contraction side passage 11 which is the other passage has a plurality of openings 11 </ b> A which open to the outer peripheral portion of the lower end surface of the piston 3. As shown in FIG. 2, in the present embodiment, the openings 11 </ b> A are rectangular, and five openings are arranged at equal intervals along the circumferential direction. The contraction side passage 11 has a plurality of openings 11 </ b> B that open to a portion from the center in the radial direction with respect to the opening 11 </ b> A and the opening 10 </ b> A of the extension side passage 10 on the upper end surface of the piston 3. In this embodiment, the openings 11B are circular like the openings 10B shown in FIG. 2, and five openings 11B are arranged at substantially equal intervals along the circumferential direction. The openings 10A and 11A may be arcuate.

  At the lower end and the upper end of the piston 3, an extension side damping force is generated that generates a damping force by controlling the flow of hydraulic fluid generated in the extension side passage 10 and the contraction side passage 11 by sliding of the piston 3 in the cylinder 2. A mechanism 12 and a contraction-side damping force generation mechanism 13 are provided. And the damping force is generated by adjusting the flow area of the hydraulic fluid by controlling the flow area of the hydraulic fluid by the piston 3 which is the valve body and the expansion side and contraction side damping force generation mechanisms 12 and 13.

The extension side damping force generation mechanism 12 will be described with reference to FIGS. 1 and 2.
A substantially circular outer sheet 14 is provided on the lower end surface of the piston 3 adjacent to the inner peripheral side of the opening portion 11A of the contraction side passage 11 so as to surround the opening portion 10B of the extension side passage 10. It protrudes. Here, “substantially circular” means a shape close to a circle that can be seated over the entire circumference of the outer seat 14 in a state in which a disk valve 17 described later is clamped, and may be an ellipse with a small eccentricity, for example. A substantially circular inner sheet 15 concentric with the outer sheet 14 protrudes downward in FIG. 1 on the inner peripheral side of the opening 10 </ b> B of the extension side passage 10. The inner sheet 15 is formed around the central opening 3C of the piston 3 into which the small diameter portion 4A at the tip of the piston rod 4 is inserted. Further, a disc support portion 16 projects downward in FIG. 1 between the outer sheet 14 and the inner sheet 15. The protruding height of the outer sheet 14, the inner sheet 15, and the disc support portion 16 is higher than that of the disc support portion 16 in the outer sheet 14, and the inner sheet 15 is equal to or lower than the protruding height of the disc support portion 16. Yes.

  In the present embodiment, a plurality of disk support portions 16 are arranged radially between the openings 10B of the extension side passage 10, that is, the same number as the openings 10B, at approximately equal intervals. It is formed integrally with the sheet 15. The disk support portion 16 has substantially the same width and extends to the vicinity of the outermost peripheral portion of the plurality of openings 10B. Further, as shown in FIG. 4, the protruding height of the disc support portion 16 is tapered so that the inner peripheral portion connected to the inner sheet 15 is the same height as the inner sheet 15 and the outer peripheral portion is gradually increased. Is formed. In addition, although this taper surface is a concave surface in the example shown in FIG. 4, it is good also as a conical surface where a cross section becomes a straight line. Although it is possible to use a convex surface, in that case, the outer peripheral side of the disk valve 17 to be described later tends to float from the convex surface (is less likely to abut), and thus the effect is lower than that of the conical surface.

  A disk valve 17 composed of a plurality of stacked disk-shaped disks is in contact with and seated on the outer sheet 14, the inner sheet 15, and the disk support portion 16. By being tightened, the inner sheet 15 is pressed and clamped via the retainer 18 and the spacer 19. At this time, the disk valve 17 is pressed against the outer sheet 14, the inner sheet 15, and the disk support 16 with initial deflection due to the difference in protruding height.

  The disc valve 17 has a large-diameter disc 17A that abuts and sits on the outer seat 14, the inner seat 15 and the disc support portion 16, and an outer diameter that is substantially the same as the distal end portion that is stacked thereon and extends radially. Are stacked on the first medium diameter disk 17B, the first medium diameter disk 17B, the second medium diameter disk 17C having a smaller diameter, and the second medium diameter disk 17C. And a small-diameter disk 17D having a smaller diameter. On the outer peripheral portion of the large-diameter disk 17A seated on the outer seat 14, a notch that forms an orifice 17E that allows the extension-side passage 10 and the cylinder lower chamber 2B to always communicate with each other is formed.

  The contraction-side damping force generation mechanism 13 is similar to the above-described extension-side damping force generation mechanism 12. A circular outer sheet 20, an inner sheet 21, and a radial disk support 22 are projected from the upper end surface of the piston 3. A disk valve 23 in which a large-diameter disk 23A, a first medium-diameter disk 23B, a second medium-diameter disk 23C, and a small-diameter disk 23D are laminated and abuts and is seated. The spacer 25 is pressed against the inner sheet 21 and clamped. At this time, the disc valve 23 is pressed against the outer seat 20, the inner seat 21, and the disc support portion 22 with initial deflection due to the difference in protruding height (outer seat> disc support portion ≧ inner seat). On the outer peripheral portion of the large-diameter disk 23A seated on the outer seat 20, a notch that forms an orifice 23E that allows the compression-side passage 11 and the cylinder upper chamber 2A to always communicate with each other is formed.

Next, the operation of the present embodiment configured as described above will be described.
During the extension stroke of the piston rod 4, the hydraulic fluid on the cylinder upper chamber 2A side is pressurized by the sliding of the piston 3 in the cylinder 2 and flows mainly to the cylinder lower chamber 2B side through the extension side passage 10 for extension. A damping force is generated by the side damping force generation mechanism 12.

  In the low piston speed range, the orifice characteristic damping force is generated by the orifices 17E and 23E of the disk valves 17 and 23. At this time, the pressurized pressure on the cylinder upper chamber 2A side does not reach the valve opening pressure of the disk valve 17, and the disk valve 17 does not open. The damping force characteristics by the orifices 17E and 23E are indicated by a curve B in FIG.

  When the piston speed increases and shifts to the middle speed range, the pressurized pressure on the cylinder upper chamber 2A side reaches the valve opening pressure of the disk valve 17, and the disk valve 17 opens to generate a damping force of the valve characteristics. To do. At this time, the large-diameter disk 17A is subjected to the spring force of the large-diameter disk 17A itself on the disk support part 16 whose protrusion height gradually increases from the inner peripheral side to the outer peripheral side and the outer sheet part 14 having the highest protrusion height. In addition, the first and second medium-diameter disks 17B and 17C and the small-diameter disk 17D are pressed with initial deflection by the spring force, and the outer peripheral side is more easily bent than the inner peripheral side.

  Thereby, the large-diameter disk 17A is first separated from the outer seat 14 by bending the outer peripheral side with the outer peripheral portion of the first medium-diameter disk 17B as a fulcrum as the pressure on the cylinder upper chamber 2A side increases. The outer periphery of the second medium diameter disk 17C is further bent together with the first medium diameter disk 17B and separated from the disk support portion 16, and then the outer periphery of the small diameter disk 17D is used as a fulcrum. It bends together with the diameter discs 17B and 17C, and further bends together with the first and second medium diameter discs 17B and 17C and the small diameter disc 17D with the spacer 18 as a fulcrum to open the valve.

  As a result, the flow passage area from the extension side passage 10 to the cylinder lower chamber 2B increases in multiple stages. Therefore, compared with the damping force characteristic of the conventional hydraulic shock absorber indicated by the broken line in FIG. The transition to characteristics can be performed smoothly, and a stable damping force can be obtained. The damping force characteristic of the shock absorber 1 according to the present embodiment is shown by a solid line in FIG. A curve B in FIG. 10 represents orifice characteristics, and curves C1, C2, C3, and C4 indicate that the large diameter disk 17A is the first medium diameter disk 17B, the second medium diameter disk 17C, the small diameter disk 17D, and the spacer 18, respectively. The characteristic when it bends as a fulcrum is shown.

  On the other hand, during the contraction stroke of the piston rod 4, the hydraulic fluid on the cylinder lower chamber 2B side is pressurized by the sliding of the piston 3 in the cylinder 2, and flows mainly to the cylinder upper chamber 2A side through the contraction side passage 11. The contraction side damping force generation mechanism 13 generates a damping force.

  As in the case of the extension stroke described above, in the piston speed low speed region, the orifice characteristic damping force is generated by the orifices 17E and 23E of the disk valves 17 and 23, and the piston speed shifts to the medium speed region and the cylinder speed changes. When the pressure on the lower chamber 2A side reaches the valve opening pressure of the disk valve 23, the disk valve 23 bends and opens to generate a damping force of the valve characteristic.

  At this time, the difference between the protruding heights of the outer sheet 20, the inner sheet 21, and the disk support 22, and the large-diameter disk 23A, the first medium-diameter disk 23B, the second medium-diameter disk 23C, and the small-diameter disk 23D are stacked. Since the flow path area from the contraction side passage 11 to the cylinder upper chamber 2A is increased in multiple stages by the valve 23, the transition from the orifice characteristic to the valve characteristic can be smoothly performed similarly to the above-described expansion stroke, and the stable Damping force can be obtained.

  In the present embodiment, since the outer sheets 14 and 20 are circular, the notches of the large diameter disks 17A and 23A forming the orifices 17E and 23E may be arranged at any position in the circumferential direction. When the diameter disks 17A and 23A are assembled to the piston 3, alignment in the circumferential direction is unnecessary, and the assemblability is excellent.

  In the above-described embodiment, the disk valves 17 and 23 include four sets having different diameters of the large diameter disks 17A and 23A, the first medium diameter disks 17B and 23B, the second medium diameter disks 17C and 23C, and the small diameter disks 17D and 23D. However, the present invention is not limited to this, and the first and second discs used in the present invention are designed so that the amount of deflection at the time of valve opening can be changed in multiple stages by the difference in deflection stiffness between the inner and outer circumferential sides. Two or more sets including one disk and the second disk may be used.

  Further, the disk support portions 16 and 22 are formed in a radial shape, but in addition to this, the inner peripheral side and the outer peripheral side may have a shape offset in the circumferential direction (for example, a shape like a spiral), Moreover, it is arrange | positioned between the outer side sheets 14 and 20 and the inner side sheets 15 and 21, and protrusion height is lower than the outer side sheets 14 and 20, and what is necessary is just more than the protrusion height of the inner side sheets 15 and 21.

  Next, second to fourth embodiments of the present invention will be described with reference to FIGS. In the following description, only the lower surface of the piston 3 corresponding to FIG. 2 of the first embodiment is shown, and the same reference numerals are used for the same parts as in the first embodiment. Only the part will be described in detail.

  As shown in FIG. 5, in the shock absorber according to the second embodiment of the present invention, the plurality of radially arranged disk support portions 16 are divided and arranged along the radial direction. The disc support portion 16A disposed opposite to the outer peripheral portion of the diameter disc 17B, the disc support portion 16B disposed opposite to the outer peripheral portion of the second medium diameter disc 17C, and the small diameter disc 17D. Disk support portion 16C. The disk support portions 16A, 16B, and 16C may be arranged at different positions in the circumferential direction. Thereby, the effect | action and effect similar to the said 2nd Embodiment can be show | played. Further, in this case, the pressure receiving area with respect to the expansion side passage 10 of the disc valve 17 is larger than that of the first embodiment.

  As shown in FIG. 6, in the shock absorber according to the third embodiment of the present invention, the radially extending disk support portion 16 has a tapered shape in which the width of the outer peripheral portion is narrower than the inner peripheral portion. Thereby, in the initial stage of opening of the disc valve 17, the flow passage area is increased, the inclination of the damping force characteristic is reduced, and the pressure receiving area with respect to the expansion side passage 10 of the inner peripheral portion of the disc valve 17 is reduced. The inner peripheral side of the disk valve 17 becomes difficult to bend, and the increase in the flow path area with respect to the increase in the piston speed can be delayed.

  Moreover, as shown in FIG. 7, in the shock absorber according to the fourth embodiment of the present invention, the radially extending disk support portion 16 has a shape in which the outer peripheral portion is wider than the inner peripheral portion. Thereby, contrary to the case of the third embodiment, in the initial stage of opening of the disc valve 17, the flow path area is reduced and the inclination of the damping force characteristic is increased, and the inner peripheral portion of the disc valve 17 is increased. Since the pressure receiving area with respect to the expansion side passage 10 is increased, the inner peripheral side of the disk valve 17 is easily bent, and the increase in the flow path area with respect to the increase in the piston speed can be accelerated.

  In the second to fourth embodiments, similar to the expansion side damping force generation mechanism 12, the compression side damping force generation mechanism 13 also has the same damping force in the compression stroke by changing the shape of the disk support portion 16. Characteristics can be obtained.

  In the first to fourth embodiments, the case where the piston 3 is used as the valve body in the single cylinder type shock absorber having the gas chamber 9 formed by the free piston 8 in the cylinder 2 is described. The invention is not limited to this, and as shown in FIG. 8, the invention can also be applied to a multi-cylinder shock absorber in which a reservoir 27 is connected to a cylinder 2 via a base valve 26 provided at the bottom thereof. . In this case, the present invention may be applied using the base valve 26 as the valve body. Furthermore, as shown in FIG. 9, in a shock absorber in which a damping force generation mechanism 28 is attached to the side portion of the cylinder 2, a valve body is provided in the damping force generation mechanism 28 on the side portion of the cylinder 2 to apply the present invention. May be. In FIGS. 8 and 9, the same parts as those in the first embodiment are denoted by the same reference numerals.

  In the first to fourth embodiments, the hydraulic shock absorber that generates the damping force by controlling the flow of the hydraulic fluid has been described. However, the present invention is not limited to this, and other types of gas such as gas may be used. The present invention can also be applied to a shock absorber that generates a damping force by controlling the flow of fluid. Note that the working fluid is preferably a working fluid from the viewpoint of the stability of the damping force characteristics.

It is a longitudinal cross-sectional view which expands and shows the piston part which is the principal part of the buffer which concerns on 1st 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 of the shock absorber shown in FIG. It is a longitudinal cross-sectional view which expands and shows the disk support part of the piston of the shock absorber shown in FIG. It is a bottom view of the piston of the buffer concerning a 2nd embodiment of the present invention. It is a bottom view of the piston of the buffer concerning a 3rd embodiment of the present invention. It is a bottom view of the piston of the buffer concerning a 4th embodiment of the present invention. It is a longitudinal cross-sectional view of the base valve part of a double cylinder type shock absorber. It is a longitudinal cross-sectional view which shows the principal part of the shock absorber in which the damping force generation mechanism was provided in the side part of the cylinder partly broken. It is a graph which shows the damping force characteristic of the shock absorber shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Buffer, 2 Cylinder, 3 Piston (valve main body), 4 Piston rod, 10 Elongation side channel | path (passage), 12 Elongation side damping force generation mechanism (damping force generation mechanism), 10B Opening part, 14 Outer seat 14 Inner seat , 16 Disc support portion 16A Large-diameter disc (first disc), 17B First medium-diameter disc (second disc)

Claims (6)

A cylinder filled with a working fluid;
A piston slidably inserted into the cylinder and defining the interior of the cylinder in two chambers;
A piston rod connected to the piston, at least one end of which projects out of the cylinder;
A passage through which the working fluid flows by sliding of the piston;
A damping force generation mechanism that is provided in a part of the passage and controls the flow of the working fluid to generate a damping force;
The damping force generation mechanism is
A valve body through which the passage extends, and
A substantially circular outer sheet projecting so as to surround the plurality of openings of the passage in the valve body;
An inner sheet protruding inside the outer sheet and having a lower protrusion height than the outer sheet;
A disk support portion that protrudes between the outer sheet and the inner sheet, has a protruding height lower than that of the outer sheet, is equal to or greater than the inner sheet, and extends radially between the plurality of openings. ,
A first disk clamped to the inner sheet, seated on the outer sheet, and abutting the disk support;
Characterized in that it comprises a first laminated on the disk, diameter at than the outer diameter of said first disk and second disk having an outer diameter which is disposed so as to be above the disk support portion A shock absorber. 2. The shock absorber according to claim 1, wherein an inner circumferential portion of the disk support portion is formed integrally with the inner sheet.   The shock absorber according to claim 2, wherein the disk support portion has a protruding height on the outer peripheral side higher than that on the inner peripheral side.   The shock absorber according to claim 3, wherein a contact surface of the disk support portion with the first disk is a tapered concave surface. A cylinder filled with a working fluid;
A piston slidably inserted into the cylinder and defining the interior of the cylinder in two chambers;
A piston rod connected to the piston, at least one end of which projects out of the cylinder;
A passage through which the working fluid flows by sliding of the piston;
A damping force generation mechanism that is provided in a part of the passage and controls the flow of the working fluid to generate a damping force;
The damping force generation mechanism is
Provided in the piston,
A substantially circular outer sheet protruding on at least one surface of the piston so as to surround the plurality of openings of the passage;
An inner sheet protruding inside the outer sheet and having a lower protrusion height than the outer sheet;
A disk support portion that protrudes between the outer sheet and the inner sheet, has a protruding height lower than that of the outer sheet, is equal to or greater than the inner sheet, and extends radially between the plurality of openings. ,
A first disk clamped to the inner sheet, seated on the outer sheet, and abutting the disk support;
Characterized in that it comprises a first laminated on the disk, diameter at than the outer diameter of said first disk and second disk outer diameter is arranged such that over said disc support section A shock absorber. A shock absorber piston provided with a working fluid passage,
A substantially circular outer sheet protruding on at least one surface so as to surround the plurality of openings of the passage;
An inner sheet protruding inside the outer sheet and having a lower protrusion height than the outer sheet;
A disk support portion that protrudes between the outer sheet and the inner sheet, has a protruding height lower than that of the outer sheet, is equal to or greater than the inner sheet, and extends radially between the plurality of openings. ,
A first disk clamped to the inner sheet, seated on the outer sheet, and abutting the disk support;
Characterized in that it comprises a first laminated on the disk, diameter at than the outer diameter of said first disk and second disk outer diameter is arranged such that over said disc support section Piston for shock absorber.

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