JP2013053651A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of generating damping forces as designed with less variation in respective products while aligning a valve case with respect to an outer cylinder.SOLUTION: The shock absorber D includes a valve case 4 which is held by a cylinder 1 and a lower cap 3 which covers the outer cylinder 1 to cap an outer cylinder 2 forming a reservoir R between the cylinder 1 and the outer cylinder. The lower cap 3 includes recessed parts 3a and projection parts 3b which are alternately arranged in the circumferential direction. Each projection part 3b has a tapered or spherical abutting surface T to be abutted on the valve case 4, and each recessed part 3a forms a space S for communicating the reservoir R with the inside of the cylinder 1 between the valve case 4 and itself. Thus, any leg part provided in the valve case of a conventional shock absorber can be eliminated. As a result, the damping forces as designed with less variation in the respective products can be generated while aligning the valve case 4 with respect to the outer cylinder 2.

Description

  The present invention relates to an improved shock absorber.

  A conventional shock absorber includes, for example, a cylinder having a piston-side chamber defined by a piston inserted therein, an outer cylinder that covers the cylinder and forms a reservoir between the cylinder, and an end of the outer cylinder. A lower cap that is closed, a valve case that is fitted to the end of the cylinder and is sandwiched between the cylinder and the lower cap and partitions the piston side chamber and the reservoir, and a fluid that is provided in the valve case and travels from the piston side chamber toward the reservoir Some are configured with a base valve that provides resistance to flow.

  The valve case includes a disc-shaped case body that fits into the cylinder end and holds the base valve, and a cylindrical leg that hangs from the outer periphery of the lower end of the case body. Has the leg part in contact with the lower cap. In this way, the legs are provided with a number of notches that allow the inside of the legs and the reservoir to communicate with each other so that the communication between the reservoir and the piston side chamber is not interrupted even when the legs are brought into contact with the lower cap.

  When assembling the shock absorber, the lower cap is welded and attached to the outer cylinder in advance, and then the valve case with the base valve assembled to the cylinder end is fitted and assembled. The valve case is inserted into the outer cylinder together with the cylinder. When adopting such an assembly process, it is necessary to align the cylinder with respect to the outer cylinder, so that the inner peripheral surface of the lower cap has a mortar shape, while the lower end surface of the leg portion of the valve case is the lower cap. It is a taper surface following the inner peripheral surface. In this way, when the lower end surface of the leg portion of the valve case is pressed against the inner peripheral surface of the lower cap, the leg portion of the valve case is guided and aligned by the inner peripheral surface of the lower cap. Is also aligned with the outer cylinder (see, for example, Patent Document 1).

  After being aligned in this way, the upper end opening of the outer cylinder is swaged to apply an axial force to the cylinder via a rod guide fitted to the upper end of the cylinder, and the cylinder and valve are moved inside the outer cylinder. The case will be fixed.

JP 2007-155080 A

  In the above-described shock absorber, the axial force acting on the cylinder by caulking the upper end facing portion of the outer cylinder acts on the leg portion provided on the valve case. Therefore, the leg portion is caused by the axial force. It is pressed against the lower cap.

  Since the cylinder is aligned with the outer cylinder by making the lower end surface of the leg portion of the valve case into a tapered surface and the inner peripheral surface of the lower cap into a mortar shape, the axial force is applied to the leg portion. Due to the above action, a moment acts to bend the leg portion inward. Since the leg is vulnerable to bending, the leg is bent and bent inward by receiving a moment, and this bend propagates to the case body so that the case body also bends and protrudes to the inside of the cylinder. Will be curved.

  Here, the case body in the valve case includes a pressure side port and a suction port for communicating the reservoir and the piston side chamber, and a base valve composed of a laminated leaf valve for opening and closing the pressure side port is laminated on the reservoir side of the case body, A check valve for opening and closing the suction port is stacked on the piston chamber side of the case body.

  If the case body bends, the base valve and check valve stacked on the case body will be bent accordingly, which will affect the valve opening pressure of the base valve and check valve, and control the amount of bending of the case body. Since this is difficult, the shock absorber cannot generate the designed damping force, and the damping force may vary from product to product.

  Therefore, the present invention has been developed to improve the above-described problems, and the object of the present invention is as designed with little variation from product to product while aligning the valve case with the outer cylinder. It is an object of the present invention to provide a shock absorber capable of generating a damping force.

  In order to solve the above-described problems, the problem-solving means of the present invention includes a cylinder, an outer cylinder that covers the cylinder and forms a reservoir between the cylinder, and a lower cap that covers the end of the outer cylinder. And a valve case that is fitted to an end of the cylinder and is sandwiched between the cylinder and the lower cap to partition the cylinder and the reservoir, and the reservoir provided from the cylinder to the reservoir A shock absorber provided with a base valve that provides resistance to the flow of fluid toward the lower cap, wherein the lower cap includes concave and convex portions provided alternately in the circumferential direction, and the convex portion of the lower cap includes the cylinder The lower cap has a tapered or spherical contact surface that protrudes inward and contacts the valve case. A gap is formed between the reservoir and the cylinder through the gap, characterized in that the communicated.

  As described above, in the shock absorber according to the present invention, the lower cap is provided with the concave portion and the convex portion, the convex portion is brought into contact with the valve case, and the reservoir and the cylinder are communicated between the concave portion and the valve case. Since the gap functioning as a passage is formed, there is no need to provide a leg portion that is vulnerable to bending in the valve case as in a conventional shock absorber. Since it is not necessary to provide a leg portion that is vulnerable to bending in the valve case, unlike the conventional shock absorber, the valve case is also affected by the moment generated in the leg portion due to the load acting on the valve case from the cylinder. The situation that it bends greatly does not occur. Therefore, in the shock absorber of the present invention, the valve case is hardly bent due to the axial force received from the cylinder. Therefore, the base valve laminated on the valve case does not cause excessive bending due to the bending of the valve case itself, and the base The valve opening pressure is as designed.

  In addition, the convex part of the lower cap protrudes inward of the cylinder and has a tapered surface or a spherical contact surface that contacts the valve case, and the concave part of the lower cap forms a gap with the valve case. A passage that communicates between the reservoir and the cylinder can be provided while exhibiting the aligning function.

  As described above, according to the shock absorber of the present invention, the valve opening pressure of the base valve stacked on the valve case can be set as designed while aligning the valve case with respect to the outer cylinder. The damping force can be generated and the problem that the damping force varies for each product can be solved.

It is a longitudinal cross-sectional view of the shock absorber in one embodiment. It is an expansion longitudinal cross-sectional view of the bottom part of the shock absorber in one embodiment. It is a top view of the lower cap of the shock absorber in one modification of one embodiment.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIGS. 1 and 2, the shock absorber D in one embodiment includes a cylinder 1, an outer cylinder 2 that covers the cylinder 1 and forms a reservoir R between the cylinder 1, and an outer cylinder 2. A lower cap 3 that covers the end of the cylinder 1, a valve case 4 that is fitted to the end of the cylinder 1 and is sandwiched between the cylinder 1 and the lower cap 3 to partition the inside of the cylinder 1 and the reservoir R; And a base valve 5 that provides resistance to the flow of fluid from the cylinder 1 toward the reservoir R.

  Further, in the present embodiment, as shown in FIG. 1, the shock absorber D is slidably inserted into the cylinder 1 in addition to the above configuration, and the cylinder 1 is divided into the expansion side chamber R1 and the pressure side chamber R2. Piston 6 to be partitioned, piston rod 7 having one end connected to piston 6 and movably inserted into cylinder 1, and closing upper ends of cylinder 1 and outer cylinder 2 in FIG. 1 and sliding piston rod 7 And a rod guide 8 that freely supports the shaft. In this example, the cylinder 1, the valve case 4, and the rod guide 8 are clamped between the crimping portion 2 a of the outer cylinder 2 and the lower cap 3 by crimping the upper end opening of the outer cylinder 2. 2 is accommodated while being positioned in the inside. Further, the extension side chamber R1 and the pressure side chamber R2 in the cylinder 1 are filled with liquid such as hydraulic oil, and the reservoir R is filled with liquid and gas. In addition to the hydraulic oil, water or an aqueous solution may be used as the liquid. Further, the gas filled in the reservoir R may be an inert gas such as nitrogen that hardly changes the properties of the liquid when the liquid is used as hydraulic oil.

  The piston 6 has an extension-side damping passage 11 that provides resistance to the flow of fluid from the extension-side chamber R1 to the compression-side chamber R2, and a piston passage 12 that allows only the flow of fluid from the compression-side chamber R2 to the extension-side chamber R1. And are provided.

  The valve case 4 is provided with a pressure side port 13 and a suction port 14. The pressure-side port 13 is opened and closed by an annular base valve 5 stacked on the non-cylinder side end that is the lower end in FIG. 1 of the valve case 4, and the flow of fluid from the cylinder 1 toward the reservoir R Only to allow. The suction port 14 is opened and closed by an annular check valve 16 stacked on the cylinder side end, which is the upper end in FIG. 1 of the valve case 4, and the fluid flow from the reservoir R into the cylinder 1. Only to allow.

  Accordingly, when the shock absorber D exhibits an extension operation in which the piston 6 moves upward in FIG. 1 with respect to the cylinder 1, the extension side damping passage extends from the extension side chamber R1 where the liquid is compressed to the compression side chamber R2. 11 to move through. Since the extension side attenuation passage 11 provides resistance to the flow of the liquid, a differential pressure is generated between the extension side chamber R1 and the compression side chamber R2, and the shock absorber D exhibits an extension side damping force that prevents extension. Note that when the buffer D is extended, the volume of liquid that causes the piston rod 7 to exit the cylinder 1 is insufficient in the cylinder 1, so that the check valve 16 is opened and the insufficient amount of liquid passes through the suction port 14. 1 is supplied.

  On the other hand, when the shock absorber D exhibits a contraction operation in which the piston 2 moves downward in FIG. 1 with respect to the cylinder 1, the piston passage 12 is moved from the compression side chamber R2 where the liquid is compressed to the expansion side chamber R1. Move through. Furthermore, since the volume of liquid that the piston rod 7 enters into the cylinder 1 becomes excessive in the cylinder 1, the excess liquid opens the base valve 15 and is discharged to the reservoir R through the pressure side port 13. . And resistance is given when a liquid passes the base valve 15, the pressure in the cylinder 1 rises, and the buffer D exhibits the compression side damping force which prevents contraction.

  As shown in FIGS. 1 and 2, the valve case 4 has a disk shape, and has a small-diameter fitting portion 17 fitted to the inner periphery of the lower end in FIG. 1 of the cylinder 1 and an outer diameter from the small-diameter fitting portion 17. Is provided with a large-diameter clamping portion 18 that is clamped between the cylinder 1 and the lower cap 3. Note that the outer periphery of the lower end in FIG. 1 of the large-diameter clamping portion 18 is chamfered in a tapered shape, and a chamfered portion 19 is provided.

  Further, the valve case 4 includes a pressure-side port 13 and a suction port 14 that pass from the upper end in FIG. 1 at the small-diameter fitting portion 17 at the cylinder side end to the lower end in FIG. An insertion hole 20 through which a guide rod 19 for fixing the base valve 5 and the check valve 16 to the valve case 3 is inserted is provided.

  In this embodiment, a plurality of pressure side ports 13 are provided on the same circumference in the valve case 4, and the suction port 14 is similarly larger than the circumference in which the pressure side port 13 is provided in the valve case 4. A plurality of ports are provided on the circumference of the diameter circle, but the number of these ports can be set arbitrarily and may be singular.

  An annular check valve 16 for opening and closing the outlet end of the suction port 14 is stacked on the upper end in FIG. 1 that is the cylinder side end of the valve case 4, and the pressure side on the lower end in FIG. An annular base valve 5 that opens and closes the outlet end of the port 13 is stacked. The base valve 5 and the check valve 16 are assembled to the outer periphery of the guide rod 19 inserted into the insertion hole 20 of the valve case 4 and held by the valve case 4. Specifically, the guide rod 19 includes a shaft portion 19a inserted into the insertion hole 20, a flange portion 19b provided at the base end of the shaft portion 19a, and a screw portion 19c provided at the tip of the shaft portion 19a. Has been. A nut 21 is screwed onto the screw portion 19 c of the guide rod 19. By doing so, the base valve 5 and the check valve 16 mounted on the outer periphery of the shaft portion 19a of the guide rod 19 are sandwiched between the flange portion 19b and the nut 21 on the inner peripheral side, and the deflection on the outer peripheral side is allowed. It is fixed to the case 4.

  As described above, the base valve 5 fixed to the valve case 4 is bent by receiving the pressure of the pressure side chamber R2 that is raised by the contraction operation of the shock absorber D, and opens the pressure side port 13 to move from the pressure side chamber R2 to the reservoir R. While allowing the flow of liquid to go, it resists that flow but blocks the flow in the opposite direction. The other check valve 16 bends when the pressure side chamber R2 is depressurized by the extension operation of the shock absorber D and opens the suction port 14 to allow the flow of liquid from the reservoir R to the pressure side chamber R2, but in the opposite direction. Block the flow. The check valve 16 is provided with a through hole so as not to close the opening end of the pressure side port 13 on the pressure side chamber side. The outer diameter of the base valve 5 is set to an outer diameter that does not block the suction port 14 and does not affect the suction port 14. In this way, the base valve 5 and the check valve 16 are designed so as not to affect the ports that are not opened and closed by the arrangement and structure of the pressure side port 13 and the suction port 14 provided in the valve case 4. Further, in this case, the base valve 5 is configured by overlapping a plurality of annular plates, but the number of the annular plates is determined according to the characteristics of the compression side damping force required for the shock absorber D.

  Subsequently, the lower cap 3 closes and closes the lower end of the outer cylinder 2. Specifically, the outer cap 2 is integrated with the outer cylinder 2 by fitting the outer periphery of the dish-like lower cap 3 to the lower end in FIG. 1 and welding these fitting portions. The lower cap 3 is a separate component from the outer cylinder 2, but the bottom may be processed as a bottom cap at the lower end of the outer cylinder 2 so that the bottom functions as a lower cap. May be formed.

  And the lower cap 3 is provided with the recessed part 3a and the convex part 3b as shown in FIG. 1 and FIG. 2 in this case. Specifically, the concave portions 3a and the convex portions 3b are provided alternately in the circumferential direction of the lower cap 3, and in this case, three each are provided. And both the recessed part 3a and the convex part 3b are the up-down direction in FIG. 1 used as the axial direction at the outer periphery of the anti-cylinder end used as the lower end of the large diameter clamping part 18 used as the non-cylinder side end of the valve case 4 at least. Are provided so as to face each other. The convex portion 3 b protrudes toward the cylinder 1, and only the convex portion 3 b abuts against the outer periphery of the opposite cylinder end of the large-diameter clamping portion 18 of the valve case 4, and the other concave portion 3 a contacts the valve case 4. A gap S is formed between the valve case 4 and the valve case 4 without contact. Further, the contact surface T of the convex portion 3b with the valve case 4 is a tapered surface having an inclination so as to move away from the valve case 4 in the axial direction toward the inner peripheral side as shown in FIG. Therefore, when an axial load is applied to the valve case 4 while bringing the outer periphery of the lower end of the large-diameter clamping portion 18 of the valve case 4 into contact with the convex portion 3b of the lower cap 3, the valve case 4 is tapered. It is designed to follow the surface. In addition, the contact surface T of the convex portion 3b with the valve case 4 is tapered, and the centering function of the valve case 4 can be similarly exerted even when the convex surface is concave. It should be noted that at least one concave portion 3a and at least one convex portion 3b may be provided. However, if the above-described alignment function is expected to be exhibited, three or more are preferable. Further, the circumferential widths of the concave portion 3a and the convex portion 3b are set to be the same as shown in the figure, but can be arbitrarily set. The lower cap 3 can be manufactured, for example, by press molding, forging, or other processing.

  In order to assemble the valve case 4 to the outer cylinder 2, a small-diameter fitting portion 17 is fitted to the lower end of the cylinder 1 in FIG. 1 and inserted into the outer cylinder 2 together with the cylinder 1, and the large-diameter clamping portion 18 is The lower end of the cylinder 2 is brought into contact with the convex portion 3b of the lower cap 3 that closes. At this time, as described above, when the valve case 4 is pressed against the convex portion 3b of the lower cap 3 through the cylinder 1, the valve case 4 is aligned by the lower cap 3 as described above, and the cylinder 1 and the valve case 4 are aligned. Is aligned with the outer cylinder 2. A chamfered portion 19 is provided on the outer periphery of the lower end of the large-diameter clamping portion 18 of the valve case 4, and the chamfered portion 19 is a tapered upper end surface that is a contact surface T with the valve case 4 in the convex portion 3 b. Therefore, when the valve case 4 is pressed against the lower cap 3, the valve case 4 smoothly slides on the contact surface T so that the cylinder 1 is reliably and smoothly aligned with the outer cylinder 2. Can be aligned. After accommodating the cylinder 1 and the valve case 4 in the outer cylinder 2, the rod guide 8 is fitted to the outer cylinder 2 and the cylinder 1, the seal member 22 is stacked, and the outer periphery of the outer cylinder 2 is crimped, The axial force due to the caulking acts on the seal member 22, the rod guide 8, the cylinder 1 and the valve case 4, and these parts are firmly fixed to the outer cylinder 2. The above-described fixing method of the cylinder 1 and the valve case 4 is an example. In addition to caulking the tube end of the outer cylinder 2, a nut having a screw part on the outer periphery that is screwed to the inner periphery of the upper end of the outer cylinder 2 is used. Alternatively, other methods may be adopted.

  Thus, the valve case 4 is fixed to the outer cylinder 2 together with the cylinder 1, so that the valve case 4 partitions the inside of the cylinder 1 and the reservoir R formed between the cylinder 1 and the outer cylinder 2. However, as described above, the recess 3a is provided between the valve case 4 and the lower cap 3, so that a clearance S is formed. The clearance S communicates between the reservoir R and the pressure side chamber R2 in the cylinder 1. Function as. Therefore, in the shock absorber D, it is not necessary to provide a cylindrical leg portion having a notch functioning as a passage at the lower end of the valve case, unlike the valve case of the conventional shock absorber.

  That is, according to the shock absorber D of the present invention, the lower cap 3 is provided with the concave portion 3a and the convex portion 3b, the convex portion 3b is brought into contact with the valve case 4, and the concave portion 3a is interposed between the valve case 4 and the lower cap 3. Since the gap S functioning as a passage communicating the reservoir R and the inside of the cylinder 1 is formed, it is not necessary to provide a leg portion that is fragile to the valve case unlike the conventional shock absorber. Since it is not necessary to provide a leg portion that is vulnerable to bending in the valve case 4, the shock absorber D of the present invention is different from the conventional shock absorber in that the valve case is affected by the moment generated in the leg portion due to the load acting on the valve case from the cylinder. The case where the case is greatly bent does not occur. Therefore, in the shock absorber D of the present invention, the valve case 4 is difficult to bend due to the axial force received from the cylinder 1, so the valve case 4 itself is bent to the base valve 5 and the check valve 16 stacked on the valve case 4. These valve opening pressures are as designed without causing excessive deflection due to the above.

  Further, the lower cap 3 includes concave portions 3 a and convex portions 3 b provided so as to be alternately arranged in the circumferential direction, and the convex portion 3 b of the lower cap 3 projects to the inside of the cylinder 1 and abuts against the valve case 4. Or spherical contact surface T, and the recess 3b of the lower cap 3 forms a gap S between the valve case 4 and the reservoir R and the cylinder 1 communicate with each other while exhibiting a centering function. A passage can be provided.

  Therefore, according to the shock absorber D of the present invention, the valve opening pressure of the base valve 5 and the check valve 16 stacked on the valve case 4 is set as designed while the valve case is aligned with the outer cylinder. Therefore, the designed damping force can be generated, so that the problem that the damping force varies for each product can be solved.

  Further, in the shock absorber D of the present invention, the valve case 4 can be fixed at a predetermined position only by the cylinder 1 and the lower cap 3, and the valve case can be fixedly attached in the middle of the cylinder or in the middle of the cylinder 1. Since it is not necessary to provide a cylindrical spacer in order to provide the valve case, it is very advantageous in terms of assembly and economy.

  Further, the valve case 4 has a disc shape, and has a small diameter fitting portion 17 fitted to the cylinder 1 and an outer diameter larger than that of the small diameter fitting portion 17 and between the cylinder 1 and the lower cap 3. A large-diameter clamping portion 18 that is clamped between the two and the outer periphery of the large-diameter clamping portion 18 is brought into contact with the convex portion 3b of the lower cap 3, thereby simplifying the shape of the valve case 4 and the convex portion of the lower cap 3. It can be centered in 3b.

  Further, as shown in FIG. 3, if the abutting portion between the convex portion 3 b and the valve case 4 falls within the range (shaded area) in which the end of the cylinder 1 is projected in the axial direction, the cylinder 1 The moment by the action of the axial force from can be reduced. In other words, the displacement of the acting line of the load applied to the large-diameter clamping portion 18 from the cylinder 1 that clamps the large-diameter clamping portion 18 of the valve case 4 and the convex portion 3b of the lower cap 3 is reduced. Can be reduced. Therefore, the contact portion between the convex portion 3b and the valve case 4 is within the range (shaded area) projected on the end of the cylinder 1 in the axial direction. In addition to the effect of reducing the bending of the valve case 4 itself by eliminating the fragile legs, the moment due to the deviation of the action line can be reduced, the bending of the valve case 4 can be further suppressed, and the damping force varies. The reduction effect becomes higher.

  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.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Outer cylinder 3 Lower cap 3a Concave part 3b Convex part 4 Valve case 5 Base valve 17 Small diameter fitting part 18 Large diameter clamping part D Buffer R Reservoir S Gap T Contact surface

Claims (3)

A cylinder, an outer cylinder that covers the cylinder and forms a reservoir between the cylinder, a lower cap that covers an end of the outer cylinder, and is fitted to the end of the cylinder and the cylinder and the A shock absorber provided with a valve case that is sandwiched between a lower cap and partitions the inside of the cylinder and the reservoir, and a base valve that is provided in the valve case and provides resistance to the flow of fluid from the inside of the cylinder toward the reservoir The lower cap has concave and convex portions provided alternately in the circumferential direction, and the convex portion of the lower cap protrudes inside the cylinder and is tapered or spherical to abut against the valve case. The recess of the lower cap forms a gap between the valve case and the reservoir and the cylinder through the gap. Communicated damper, characterized in that passed. The valve case is disc-shaped, and has a small-diameter fitting portion fitted into the cylinder and an outer diameter larger than that of the small-diameter fitting portion, and is sandwiched between the cylinder and the lower cap. The shock absorber according to claim 1, further comprising a large-diameter clamping portion, and a non-cylinder end outer periphery of the large-diameter clamping portion is in contact with the convex portion. The shock absorber according to claim 2, wherein an outer edge of the large-diameter clamping portion that comes into contact with the convex portion is chamfered.

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