JP6128652B2 - Shock absorber - Google Patents

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 is caught by 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. The resin cushion has a press-fit portion that is press-fitted into the inner periphery of the end portion of the coil spring, and the inner diameter of one or both of the end winding portions at which the press-fit portion of the resin cushion of the coil spring is press-fitted is : on SL are expanded to press fit possible the press-fit portion of the resin cushion, when expanded inside diameter of the seat winding portion Half portion to half from the end of the seat winding portion, characterized in that widened toward the gradually outwardly as it goes to the end from the base of the half portions.

  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 wound portion, it may be caught in the middle or 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 an enlarged plan view of the rebound spring of the shock absorber in one modification of the embodiment of the present invention. (A) It is a partial expanded longitudinal cross-sectional view of the rebound spring of the buffer in the other modification of one embodiment of this invention. (B) It is an enlarged plan view of the rebound spring of the shock absorber in another modification of the embodiment of the present 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 6 and an annular resin cushion 8 attached to the end of the rod guide side which is the upper end of the coil spring 6 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. In this case, the convex portion 7d is three circumferentially provided with equal intervals, with a tension force to the outer circumference of the inner piston rod is inserted into the circumferential 3 abuts resin cushion 7 the piston rod 3 It is to be fixed to the outer periphery of the. 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.

  Further, 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 brought into 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.

  The resin cushion 7 configured as described above is integrated with the coil spring 6 by press-fitting the press-fit portion 7b into the inner periphery of the end winding portion 6a of the coil spring 6, and also in the resin cushion 8, the coil spring 6 The press-fitting portion 8b is press-fitted into the inner periphery of the end winding portion 6b so as to be integrated with the coil spring 6.

When the rebound spring S is mounted on the outer periphery of the piston rod 3, when the resin cushion 8 comes into contact with the rod guide 4 and the coil spring 6 is compressed during the extension operation of the shock absorber D in which the piston 2 moves upward in FIG. The coil spring 6 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.

  Here, the inner diameter of the end winding portions 6a and 6b of the coil spring 6 is larger than the inner diameter of the spring portion 6c between the end winding portions 6a and 6b that can generate an elastic force as a spring of the coil spring 6. is there. The inner diameter of the end turn portion 6a is such that even if the press-fit portion 7b of the resin cushion 7 is press-fitted into the end turn portion 6a, insertion of the press-fit portion 7b does not become difficult due to the tight force with which the end turn portion 6a tightens the press-fit portion 7b. Is set to Specifically, the inner diameter of the end turn 6a is made smaller than the maximum outer diameter of the press-fit portion 7b of the resin cushion 7, and the press-fitting allowance (from the maximum outer diameter of the press-fit portion 7b of the resin cushion 7 to the end turn 6a However, even if the press-fit portion 7b is inserted into the end turn portion 6a and the diameter is increased, the end of the end turn portion 6a is damaged by the press-fit portion 7b. The diameter is set such that the entire press-fit portion 7b is not difficult to be caught by the press-fit portion 7b. Depending on the thickness of the coil spring 6, the pressing force of the press-fitting portion 7b to press the press-fitting portion 6b changes the tightening force of the press-fitting portion 7b, so that the press-fitting allowance depends on the rigidity of the end portion 6a of the coil spring 6. You only have to decide how much you want. The resin cushion 7 is provided with a taper portion 7c at the press-fitting portion 7b, and when the press-fitting portion 8b is press-fitted into the inner circumference of the end turn portion 6a of the coil spring 6, it is wound by the degree of insertion of the press-fitting portion 7b. Since the diameter of the portion 6a is gradually increased, it is easy to press-fit the press-fit portion 7b of the resin cushion 7 into the end turn portion 6a.

  Further, regarding the inner diameter of the end turn part 6b, even if the press-fit part 8b of the resin cushion 8 is press-fitted into the end turn part 6b, it is difficult to insert the press-fit part 8b due to the tightening force with which the end turn part 6b tightens the press-fit part 8b. It is set not to become. Specifically, the inner diameter of the end turn 6b is made smaller than the maximum outer diameter of the press-fit portion 8b of the resin cushion 8, and the press-fitting allowance (from the maximum outer diameter of the press-fit portion 8b of the resin cushion 8 to the end turn 6b. However, even if the press-fit portion 8b is inserted into the end turn portion 6b and the diameter is increased, the end of the end turn portion 6b may be wound around the press-fit portion 8b or the end may be damaged. The diameter is set such that the entire press-fitting portion 8b is not difficult to be caught by the press-fitting portion 8b. Depending on the thickness of the coil spring 6, the pressing force by which the end winding portion 6 b presses the press-fitting portion 8 b changes due to the press-fitting of the press-fitting portion 8 b, and the press-fitting allowance depends on the rigidity of the end winding portion 6 b of the coil spring 6. You only have to decide how much you want. The resin cushion 8 is provided with a taper portion 8c at the press-fitting portion 8b. When the press-fitting portion 8b is press-fitted into the inner periphery of the end turn portion 6b of the coil spring 6, the end portion 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.

  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.

  Even when the spring multiplier of the coil spring 6 is increased, it is not necessary to change the shape of the resin cushions 7 and 8, so that the outer diameters of the press-fit portions 7b and 8b are different according to the coil springs 6 having different specifications. There is no problem that a number of resin cushions 7 and 8 must be prepared. Therefore, since the rebound spring S can be configured by replacing only the coil spring 6 while using one type of resin cushions 7 and 8 respectively, parts management is easy and the production cost of the shock absorber D can be reduced. At the same time, misassembly of the resin cushions 7 and 8 can be prevented.

  In addition, when expanding the inner diameter of the end turns 6a, 6b, as shown in FIG. 3, when the end turns 6a, 6b are formed by one round of the wire, for example, the end turns 6a, You may make it expand a diameter by expanding a part (half circumference part) toward the outer side from the front-end | tip U which is the terminal of 6b to a half circumference. In that case, as shown in FIG. 3, the half-circular portion may be expanded outward so that the curvature gradually decreases from the base T toward the tip U, or the half-circular portion is bent from the base T. The base T to the tip U may be expanded outward without changing the curvature. The process of expanding the half-circumferential part from the end of the end winding parts 6a, 6b to the outside is very advantageous in terms of the manufacturing cost of the shock absorber D because the work cost is low, and the end of the end winding parts 6a, 6b is a press-fit part. Since it becomes difficult to contact 7b, 8b, it is possible to prevent the end press-fitting portions 7b, 8b from being twisted when the press-fitting portions 7b, 8b are press-fitted into the end turns 6a, 6b.

Furthermore, as shown in FIG. 4, when the end winding portions 6a and 6b are formed by one round of the filament, at least the end winding portions 6a and 6b, as shown in FIGS. A flat surface portion 6d, 6e is formed by surface-grinding the half-circumferential portion from the tip which is the end of 6b, and the inner peripheral side of the half-circumferential portion of the end winding portions 6a, 6b is chamfered to chamfer 6f, By providing 6g, as shown in FIG. 4 (B), the center diameter itself of the coil spring 6 does not change, but the inner diameter of the chamfered portions 6f, 6g can be increased, and the end wound portion 6a, The overall inner diameter of 6b can be made larger than the inner diameter of the spring portion 6c. The surface grinding and chamfering of the end turn parts 6a, 6b is very advantageous in terms of the manufacturing cost of the shock absorber D because the work cost is low, and the inner periphery of the end turn parts 6a, 6b is chamfered. since it becomes difficult to galling the press-fit portion 7b, 8 b, press-fit portion 7b, the wound seat portion 6a of 8b, press-fit portion 7b of the end upon stuffing to 6b, and 8b galling can be prevented.

  It is also possible to widen the inner diameter of the end winding parts 6a and 6b by spreading the half peripheral part from the end of the end winding parts 6a and 6b to the outside and subjecting the half peripheral part to surface grinding and chamfering to the inner periphery. it can.

  Moreover, although the inside diameter of both the end winding parts 6a and 6b of the coil spring 6 is expanded in the above place, the press-fitting failure can be achieved by increasing the inner diameter of either one of the end winding parts 6a and 6b. Reduction is possible.

  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 part

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.
The resin cushion has a press-fit portion that is press-fitted into the inner periphery of the end portion of the coil spring.
An inner diameter at one or both of the end turn portions at both ends of the press-fitting portion of the resin cushion of the coil spring is press-fitted is expanded so as to be press-fitted in the press-fitting portions of the upper Symbol resin cushion,
When expanding the inner diameter of the end turn part, a half circumference part from the end of the end turn part to a half turn is gradually widened outward toward the end from the root of the half turn part. Shock absorber. 2. The shock absorber according to claim 1, wherein the end winding portion is formed by one turn of a wire strip of the coil spring . The shock absorber according to claim 1 or 2, wherein at least a half-circumferential portion of the end winding portion is surface ground .

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