JP2015148268A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber including a rebound spring capable of reducing failures in pressing of resin cushions into a coil spring.SOLUTION: To solve the above object, a shock absorber D as issue solving means of this invention includes a cylinder 1, a piston 2 slidably inserted into the cylinder 1, a piston rod 3 movably inserted through the cylinder 1 and connected at one end to the piston 2, and a rebound spring S mounted on the outer periphery of the piston rod 3. Resin cushions 7, 8 have press-fit portions 7b, 8b to be pressed into the inner peripheries of the ends of a coil spring 6, and the press-fit portions 7b, 8b have cross-section outer shapes such that they have partial contact with end coil portions 6a, 6b of the coil spring 6 in the peripheral directions.

Description

  The present invention relates to a shock absorber.

  Conventional shock absorbers consist of coil springs that are fitted with resin cushions at both ends between a rod guide that seals the cylinder end and pivotally supports the piston rod, and a flange that is provided at the intermediate portion of the piston rod. A rebound spring is interposed, and this rebound spring is compressed by a rod guide and a flange that are close to each other when the shock absorber extends, thereby exerting a spring force that suppresses the expansion of the shock absorber. It is designed to relieve the impact at the maximum extension.

  For example, in the rebound spring disclosed in Patent Document 1, the resin cushion is coiled by press-fitting a cylindrical press-fit portion of a resin cushion called a holder to the inner circumferences of both ends of the coil spring. It is designed to be fixed to the spring.

JP 2004-84776 A

  By the way, the shock absorber is interposed between the vehicle body of the vehicle and the suspension arm that holds the wheel. However, when the lever ratio is small, the stroke amount of the shock absorber is small with respect to the vertical displacement of the wheel. . If the lever ratio is reduced in this way, the shock absorber must exert a large damping force with a small stroke amount, but by using the elastic force generated when the rebound spring is compressed, There is a case where a device for exerting a large damping force is made.

  When considering using the elastic force of the rebound spring, it is advantageous to increase the spring multiplier of the coil spring. However, the spring multiplier of the coil spring is increased while avoiding an increase in the outer diameter of the shock absorber as much as possible. In order to achieve this, measures are taken to increase the wire diameter of the coil spring.

  However, if the wire diameter of the coil spring is increased, the rigidity of the wire diameter increases, so even if the resin cushion is pressed into the inner periphery of both ends of the coil spring, it is difficult to expand the diameter of both ends. Press-fit failure where the press-fit part is crushed and damaged by the end of the coil spring, or the press-fit part gets caught in the coil spring during the press-fitting, making it difficult for the press-fit part to enter the coil spring. There is a problem that occurs.

  Therefore, the present invention was devised in order to improve the above-described adverse effects, and the object of the present invention is to provide a shock absorber having a rebound spring that can reduce the press-fitting failure of the resin cushion to the coil spring. Is to provide.

  In order to solve the above-described object, the problem-solving means of the present invention includes a cylinder, a piston slidably inserted into the cylinder, a movably inserted into the cylinder, and one end of the piston to the piston. A piston rod to be connected; and a rebound spring mounted on an outer periphery of the piston rod. The rebound spring includes a coil spring and two resin cushions mounted on both ends of the coil spring. One or both of the resin cushions have a press-fit portion that is press-fitted into the inner periphery of the end portion of the coil spring, and the cross-sectional outer shape of the press-fit portion is the seat at both ends where the press-fit portion of the coil spring is press-fitted. It is characterized by having a shape that makes partial contact with the winding portion in the circumferential direction.

  According to the shock absorber of the present invention, even when the wire diameter of the coil spring of the rebound spring is increased, when the press-fitted portion of the resin cushion is press-fitted into the end turn portion, it is caught in the middle or the press-fitted portion is damaged. Therefore, the press-fitting failure can be reduced.

It is a longitudinal cross-sectional view of the shock absorber in one embodiment of the present invention. It is a partial expanded longitudinal cross-sectional view of the shock absorber in one embodiment of the present invention. It is a top view of the resin cushion of the shock absorber in one embodiment of the present invention. It is a top view of the other resin cushion of the buffer in one embodiment of the present invention. (A) It is a top view of another resin cushion of the shock absorber in one embodiment of the present invention. (B) It is sectional drawing of another resin cushion of the buffer in one embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the shock absorber D according to the embodiment includes a cylinder 1, a piston 2 slidably inserted into the cylinder 1, a movably inserted through the cylinder 1, and one end thereof being a piston 2 and a rebound spring S attached to the outer periphery of the piston rod 3.

  Hereinafter, each part will be described in detail. The cylinder 1 has a bottomed cylindrical shape, and an annular rod guide 4 is attached to the upper end in FIG. The rod guide 4 seals the upper end opening of the cylinder 1 and the piston rod 3 is inserted through the inner periphery thereof. The piston rod 3 is slidably supported by the rod guide 4.

  The cylinder 1 is partitioned into an extension side chamber R1 above the piston 2 in FIG. 1 and a compression side chamber R2 below the piston 2 in FIG. 1 by a piston 2 inserted into the cylinder 1. The side chamber R1 and the pressure side chamber R2 are filled with a liquid such as hydraulic oil. In the case of the shock absorber D, a free piston 5 is slidably inserted into the cylinder 1 below the piston 2, and gas is filled into the cylinder 1 below the free piston 5. An air chamber G is formed.

  The piston 2 is provided with a passage 2a communicating the extension side chamber R1 and the pressure side chamber R2, and a damping valve 2b as a damping force generating element provided in the middle of the passage 2a. When the shock absorber D is extended and the expansion side chamber R1 is compressed by the piston 2, the liquid in the expansion side chamber R1 passes through the passage 2a and moves to the compression side chamber R2. At this time, the damping valve 2b A resistance is applied to the flow to increase the pressure in the extension side chamber R1 to cause a difference in pressure between the extension side chamber R1 and the pressure side chamber R2. When the shock absorber D is contracted, the pressure side chamber R2 is compressed by the piston 2, and the liquid in the pressure side chamber R2 passes through the passage 2a and moves to the expansion side chamber R1, but at this time, the damping valve 2b A resistance is given to the flow of the liquid, and the pressure of the pressure side chamber R2 is increased to cause a difference between the pressures of the pressure side chamber R2 and the extension side chamber R1.

  Therefore, during the expansion operation, the shock absorber D compresses the expansion side chamber R1 with the piston 2 to increase the pressure in the expansion side chamber R1 to cause a difference in the pressure in the compression side chamber R2, and this differential pressure acts on the piston 2. Then, a force that prevents the piston 2 from moving upward in FIG. 1 is output as a damping force. On the other hand, during the contraction operation, the shock absorber D compresses the pressure side chamber R2 with the piston 2 to increase the pressure in the pressure side chamber R2 to cause a difference in the pressure in the extension side chamber R1, and this differential pressure acts on the piston 2. Then, a force that prevents the piston 2 from moving downward in FIG. 1 is output as a damping force.

  In the case of the shock absorber D, when the expansion / contraction operation is performed, the piston rod 3 moves in and out of the cylinder 1, so that the volume of the piston rod 3 that can be pushed in the cylinder 1 changes. By moving up and down in the cylinder 1, it is absorbed by the volume change of the air chamber G. As described above, the shock absorber D is a so-called single rod single-tube shock absorber. However, an outer cylinder or a tank is provided outside the cylinder 1, and a gas is provided between the outer cylinder and the cylinder 1 or in the tank. And a liquid-filled reservoir, and a rebound-type shock absorber that absorbs the displacement volume of the piston rod 3 by the reservoir. Further, the shock absorber D may be a double rod type shock absorber in which the piston rod 3 is inserted into the expansion side chamber R1 and the compression side chamber R2.

  Further, in this case, the damping valve 2b provided in the piston 2 is a throttle that allows both the flow of liquid from the expansion side chamber R1 to the compression side chamber R2 and, conversely, the flow of liquid from the compression side chamber R2 to the expansion side chamber R1. However, a plurality of passages 2a are provided, a part of which is provided with a damping valve that allows only the flow of liquid from the extension side chamber R1 to the pressure side chamber R2, and the remaining part from the pressure side chamber R2 to the extension side chamber R1. You may make it provide with the damping valve which accept | permits only the flow of the liquid which goes. Furthermore, the passage 2a and the damping valve 2b can be provided in addition to the piston 2, and can be provided in the piston rod 3 or outside the cylinder 1, for example.

  The piston rod 3 is mounted with a piston 2 at the tip which is the lower end in FIG. 1, and the upper end in FIG. 1 protrudes outside the cylinder 1 through the inner periphery of the rod guide 4. A flange-shaped spring seat 3a is provided on the lower outer periphery of the piston rod 3 in FIG.

  The rebound spring S is attached to the coil spring 6 disposed on the outer periphery of the piston rod 3 through which the piston rod 3 is inserted, and to the spring seat side end which is the lower end of the coil spring 6 in FIG. An annular resin cushion 7 fixed to the outer periphery of the coil spring, and an annular resin cushion 8 attached to the end of the rod guide side which is the upper end of the coil spring 2 in FIG. It is configured with.

  The coil spring 6 includes an end winding portion 6a at the lower end of the spring seat in FIGS. 1 and 2 and an end winding portion 6b at the upper end of the rod guide in FIGS.

  In this case, the resin cushion 7 is formed of a hard resin material. As shown in FIG. 2, the resin cushion 7 has an annular cushion body 7a and a cylindrical shape whose outer diameter rises from the inner peripheral side of the cushion body 7a and whose outer diameter is smaller than that of the cushion body 7a. The press-fitting portion 7b, a taper portion 7c provided on the outer periphery of the upper end in FIG. 2 of the press-fitting portion 7b, and a plurality of convex portions 7d provided on the inner periphery of the cushion body 7a. And the cross-sectional external shape of the press-fit part 7b in the resin cushion 7 in the shock absorber D of this embodiment is an ellipse as shown in FIG.

  The resin cushion 7 configured in this way is integrated with the coil spring 6 by press-fitting the press-fit portion 7b into the inner periphery of the end-wound portion 6a of the coil spring 6, but is press-fitted into the end-wound portion 6a. At this time, two portions where the major axis of the cross-sectional outer shape of the press-fit portion 7b that is elliptical and the outer periphery of the press-fit portion 7b intersect with each other are in contact with the inner periphery of the end turn portion 6a.

  Since the press-fit portion 7b in the resin cushion 7 partially contacts the end winding portion 6a in the circumferential direction, the degree of diameter expansion of the end winding portion 6a is small compared to the case where the end winding portion 6a contacts the end winding portion 6a all around. The tightening force with which the winding portion 6a tightens the press-fit portion 7b is reduced, and only the portion of the press-fit portion 7b that contacts the end winding portion 6a is deformed, so that the apparent rigidity of the press-fit portion 7b with respect to radial compression is reduced. . Thus, when the press-fit portion 7b of the resin cushion 7 is press-fitted into the end turn portion 6a, the tightening force of the end turn portion 6a is reduced and the rigidity of the press-fit portion 7b is reduced, so that the press-fit portion 7b becomes the end turn portion 6a. Even if the diameter of the press-fitting portion 7b is increased by inserting the inner end of the press-fitting portion 7b, the end turn portion 6a is not damaged by hitting the press-fit portion 7b or caught by the press-fit portion 7b.

  In this embodiment, the three convex portions 7d are provided at equal intervals in the circumferential direction, and come into contact with the outer periphery of the piston rod 3 inserted in the inner periphery with an urging force. Is fixed to the outer periphery of the piston rod 3. Further, the lower end of the resin cushion 7 is brought into contact with the above-described spring seat 3a, and the downward movement in FIG. In addition, the number of installation of the convex part 7d should just be three or more, and is arbitrary.

  In this case, the other resin cushion 8 is formed of a hard resin material. As shown in FIG. 2, the outer cushion body 8a has an annular cushion body 8a and an outer diameter depending on the inner peripheral side of the cushion body 8a. A small-diameter cylindrical press-fit portion 8b, a taper portion 8c provided on the outer periphery of the lower end of the press-fit portion 8b in FIG. 2, and an annular convex portion 8d provided inwardly on the inner periphery of the cushion body 8a. It is configured. And as shown in FIG. 4, the press-fit part 8b of the resin cushion 8 in the shock absorber D of this embodiment is provided with notches 8e by dropping six surfaces at equal intervals in the circumferential direction.

  The resin cushion 8 thus configured is integrated with the coil spring 6 by press-fitting the press-fit portion 8b into the inner periphery of the end-wound portion 6b of the coil spring 6, but is press-fitted into the end-wound portion 6b. At this time, the portion other than the portion where the notch 8e of the press-fit portion 8b is provided comes into contact with the inner periphery of the end turn portion 6b.

  Since the press-fitting portion 8b in the resin cushion 8 partially contacts the end winding portion 6b in the circumferential direction, the degree of diameter expansion of the end winding portion 6b is small compared to the case where the end winding portion 6b contacts the entire end periphery. The tightening force by which the winding portion 6b tightens the press-fit portion 8b is reduced, and only the portion of the press-fit portion 8b that contacts the end winding portion 6b is deformed, so that the apparent rigidity of the press-fit portion 8b with respect to the radial compression is reduced. . Thus, when the press-fit portion 8b of the resin cushion 8 is press-fitted into the end turn portion 6b, the tightening force of the end turn portion 6b is lowered and the rigidity of the press-fit portion 8b is lowered, so that the press-fit portion 8b becomes the end turn portion 6b. Even if the diameter of the press-fitting portion 8b is increased by being inserted into the press-fitting portion 8b, the end-wound portion 6b does not get damaged by hitting the press-fit portion 8b or caught by the press-fit portion 8b. The number of cutouts 8e can be set arbitrarily. Further, the resin cushion 8 is provided with a taper portion 8c at the press-fitting portion 8b, and when the press-fitting portion 8b is press-fitted into the inner periphery of the end turn portion 6b of the coil spring 6, it is wound by the degree of insertion of the press-fitting portion 8b. Since the diameter of the portion 6b is gradually increased, the press-fitting portion 8b of the resin cushion 8 can be easily pressed into the end winding portion 6b.

  The inner diameter of the resin cushion 8 is set to be larger than the outer diameter of the piston rod 3, and the convex portion 8d is in sliding contact with the outer periphery of the piston rod 3 inserted in the inner periphery. 3 is allowed to slide in the axial direction and move up and down in FIGS. In addition, the convex part 8d is made into an annular shape, and it is also possible to adopt a projecting structure similar to the convex part 8d of the resin cushion 8.

  As described above, according to the shock absorber D of the present invention, even if the wire diameter of the coil spring 6 of the rebound spring S is increased, the press-fit portions 7b and 8b of the resin cushions 7 and 8 are press-fitted into the end turns 6a and 6b, respectively. In doing so, there is no possibility of being caught in the middle or damaging the press-fit portions 7b and 8b, so that press-fit defects can be reduced.

  When the press-fit portions 7b and 8b of the resin cushions 7 and 8 are press-fitted into the end turn portions 6a and 6b, the press-fit portion 7b is used to make the press-fit portions 7b and 8b partially contact the end turn portions 6a and 6b. , 8b cross-sectional outer shape of the part facing the end winding parts 6a, 6b, that is, the outer peripheral cross-sectional shape of the part may be a shape other than a perfect circle, for example, a star, polygon, serration, etc. The shape may be such that a groove is provided on the outer periphery.

  Further, as shown in FIGS. 5A and 5B, the press-fit portion 7b is provided with one or more slits 7e, and in the illustrated case, four slits 7e, so that the press-fit portion 7b is contracted in the radial direction. You may make it make rigidity low with respect to radial deformation. By providing the slit 7e in this manner, the rigidity of the press-fitted portion 7b is reduced with respect to the diameter-reducing deformation in the radial direction, so that the press-fitted portion 7b is press-fitted into the end wound portion 6a and tightened by the end turn portion 6a. In this case, the same effect as described above can be obtained, and the press-fitting failure can be reduced when press-fitting into the end turns 6a and 6b of the press-fitting part 7b. The slits 7e can be provided in any number, and can be provided in the press-fit portion 7b along the axial direction, or can be provided obliquely with respect to the axial direction. Moreover, it is also possible to provide the slits in the press-fit portions 7b and 8b of the resin cushions 7 and 8 shown in FIGS. Further, the press-fit portions 7b and 8b of the resin cushion 7 and the resin cushion 8 can be formed in the same shape.

  The press-fit portions 7b and 8b of both the resin cushion 7 and the resin cushion 8 are partially in contact with the end winding portions 6a and 6b in the circumferential direction, but either the resin cushion 7 or the resin cushion 8 is press-fit. Even if only the portions 7b and 8b are in the shape of partial contact with the end turn portions 6a and 6b, the press-fitting failure can be reduced.

  When the rebound spring S configured as described above is attached to the outer periphery of the piston rod 3, the resin cushion 8 comes into contact with the rod guide 4 during the extension operation of the shock absorber D in which the piston 2 moves upward in FIG. When the coil spring 2 is compressed, the coil spring 2 generates a resilient force that prevents the piston 2 from moving upward in FIG. In addition, during the expansion operation, the shock absorber D compresses the expansion side chamber R1 with the piston 2 as described above to increase the pressure in the expansion side chamber R1, thereby causing a difference in the pressure in the compression side chamber R2. A force acting on the piston 2 to prevent the piston 2 from moving upward in FIG. 1 is generated. Therefore, if the rebound spring S is compressed when the shock absorber D is extended, the total of the force that prevents the movement of the piston 2 due to the pressure difference and the elastic force that prevents the movement of the piston 2 generated by the rebound spring S is buffered. This is the total damping force generated by the container D.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

1 Cylinder 2 Piston 3 Piston rod S Rebound spring 6 Coil springs 7 and 8 Resin cushions 7b and 8b Press-fit portion 7e Slit 8e Notch

Claims (3)

A cylinder,
A piston slidably inserted into the cylinder;
A piston rod movably inserted into the cylinder and having one end connected to the piston;
A rebound spring mounted on the outer periphery of the piston rod,
The rebound spring has a coil spring and two resin cushions attached to both ends of the coil spring.
One or both of the resin cushions have a press-fit portion that is press-fitted into the inner periphery of the end portion of the coil spring,
The shock absorber according to claim 1, wherein a cross-sectional outer shape of the press-fitting portion is a shape in which the press-fitting portion of the coil spring is in partial contact with the end winding portion into which the press-fitting portion is pressed. The shock absorber according to claim 1, wherein a slit is formed in the press-fitted portion or a notch is formed on an outer periphery of the press-fitted portion so as to make partial contact with the end turn portion in the circumferential direction. . The shock absorber according to claim 1, wherein a cross-sectional shape of the press-fitting portion is made elliptical so as to be brought into partial contact with the end turn portion in the circumferential direction.

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