Shock absorber

Abstract

The present invention addresses the problem of shortening the total length of a shock absorber that is attached in a sideways orientation. A protrusion that protrudes radially outward is formed at an end part on one end side of a valve body (second cylinder bottom part member), the protrusion being fitted into a recess formed in the bottom part of a base cap (first cylinder bottom part), whereby the valve body is positioned in a circumferential direction (rotation direction having a center line of the shock absorber as an axis) with respect to the base cap. Thus, it is not necessary to ensure a wall thickness for machining a fitting hole for a positioning pin in the base cap or the valve body, and the total length (basic length) can be reduced relative to that of a conventional shock absorber.

Description

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[0001] The present invention relates to a shock absorber that is mounted laterally.

[0002] Patent Document 1 discloses a shock absorber that is mounted horizontally and uses a pin to position the base cap and the valve body circumferentially (in the direction of rotation around the center line of the shock absorber) (hereinafter referred to as a "conventional shock absorber").

[0003] JP 2015-224780 A

[0004] In conventional shock absorbers, it is necessary to ensure sufficient thickness to process pin fitting holes in the base cap and valve body, which results in a problem of the overall length of the shock absorber.The present invention aims to shorten the overall length of a shock absorber that is installed sideways.

[0005] The shock absorber of the present invention is characterized by comprising: a convex portion formed on the second cylinder bottom member and protruding radially outward; and a concave portion formed on the first cylinder bottom member and accommodating the convex portion. The shock absorber of the present invention is characterized by comprising: a groove portion formed on the sealing surface of the second cylinder bottom member with the first cylinder bottom member, which connects the reservoir chamber and the third chamber; and a protrusion formed on the first cylinder bottom member and protruding inward of the groove.

[0006] According to one embodiment of the present invention, the overall length of the shock absorber that is mounted laterally can be shortened.

[0007] FIG. 1 is a cross-sectional view of a cylinder body of a shock absorber according to a first embodiment. FIG. 2 is an explanatory diagram of the first embodiment, showing a state in which a valve body is assembled to a base cap. FIG. 3 is an explanatory diagram of the first embodiment, showing a perspective view of the base cap. FIG. 4 is an explanatory diagram of the first embodiment, showing a perspective view of the valve body. FIG. 5 is an explanatory diagram of a second embodiment, showing a state in which a valve body is assembled to a base cap. FIG. 6 is an explanatory diagram of the second embodiment, showing a perspective view of the base cap. FIG. 7 is an explanatory diagram of the second embodiment, showing a perspective view of the valve body. FIG. 8 is an explanatory diagram of a third embodiment, showing a state in which a valve body is assembled to a base cap. FIG. 9 is an explanatory diagram of the third embodiment, showing a perspective view of the base cap. FIG. 10 is an explanatory diagram of the third embodiment, showing a perspective view of the valve body. FIG. 11 is a perspective view of a base cap on which a protrusion is formed to serve as a marker for the installation direction of the shock absorber.

[0008] A first embodiment of the present invention will be described with reference to the accompanying drawings. In the first embodiment, a twin-tube horizontally mounted bi-flow hydraulic shock absorber 1 (hereinafter referred to as "shock absorber 1") that is mounted sideways ("horizontally" in the first embodiment) between the carbody and bogie of a railway vehicle (not shown) will be described as an example. For convenience, the right side in Fig. 1 will be referred to as "one end side," the left side in Fig. 1 will be referred to as "the other end side," the left-right direction in Fig. 1 will be referred to as "the axial direction of shock absorber 1," and the up-down direction in Fig. 1 will be referred to as "the up-down direction."

[0009] As shown in FIG. 1 , shock absorber 1 has a cylindrical base shell 3 (first cylinder), a cylinder 2 (second cylinder) concentrically disposed within base shell 3, and an annular reservoir chamber 4 formed between cylinder 2 and base shell 3. Shock absorber 1 has a base cap 31 (first cylinder bottom) formed at one end 5 of base shell 3. Base cap 31 is formed in a cylindrical shape with a bottom, and a cylindrical portion 32 is fitted into a cap fitting portion 7 formed on the inner periphery of one end 5 of base shell 3. One end 5 of base shell 3 and bottom 32 of base cap 31 are joined by a full-circumference weld 8. Note that one end of bottom 33 of base cap 31 is joined to mounting member 23, which is connected to the vehicle body.

[0010] The shock absorber 1 has a piston 9 slidably inserted into a cylinder 2. The piston 9 divides the interior of the cylinder 2 into a first chamber 2A at the other end and a second chamber 2B at one end. The piston 9 has an extension-side relief valve 16 that opens when the hydraulic pressure in the first chamber 2A reaches a set pressure during the extension stroke of a piston rod 10, thereby releasing the pressure (hydraulic fluid) in the first chamber 2A to the second chamber 2B. The piston 9 has an extension-side orifice passage 18 that generates a damping force with orifice characteristics during the extension stroke of the piston rod 10. The piston 9 has a compression-side relief valve 17 that opens when the hydraulic pressure in the second chamber 2B reaches a set pressure during the compression stroke of the piston rod 10, thereby releasing the pressure (hydraulic fluid) in the second chamber 2B to the first chamber 2A. The piston 9 has a compression-side orifice passage 19 that generates a damping force with orifice characteristics during the compression stroke of the piston rod 10.

[0011] The shock absorber 1 has a piston rod 10, one end 11 (first end) of which is connected to the piston 9. The other end 12 (second end) of the piston rod 10 is inserted into a rod guide 13 attached to the other end of the cylinder 2 and the base shell 3, and extends to the outside of the cylinder 2. An attachment member 22 connected to the bogie side is joined to the end 12 of the piston rod 10. A cylindrical cover 26 (partially shown in FIG. 1 ) is attached to the end 12 of the piston rod 10, covering the piston rod 10 that protrudes to the outside from the cylinder body 25.

[0012] The base shell 3 has an internal thread (reference numeral omitted) formed on the inner periphery of the end portion 6 on the other end side. A disk-shaped lock ring 14 having an external thread (reference numeral omitted) formed on the outer periphery is attached to the internal thread of the base shell 3. In the shock absorber 1, an axial force is generated in the cylinder 2 by tightening the lock ring 14 attached to the base shell 3 and pressing the washer 15 and rod guide 13 toward one end.

[0013] The shock absorber 1 has a base valve 45 that controls the flow of hydraulic fluid between the second chamber 2B and the reservoir chamber 4. The base valve 45 separates the second chamber 2B from the reservoir chamber 4 and has a valve body 51 (second cylinder bottom member) that defines the third chamber 21 between the base valve 45 and the base cap 31. The valve body 51 has passages 46 and 47 that communicate the second chamber 2B and the third chamber 21. A check valve 48 is provided in the passage 46 to allow hydraulic fluid to flow from the third chamber 21 to the second chamber 2B. A relief valve 49 is provided in the passage 47. The relief valve 49 opens when the hydraulic pressure in the second chamber 2B reaches a set pressure, releasing the pressure (hydraulic fluid) in the second chamber 2B to the reservoir chamber 4 via the third chamber 21. Hydraulic fluid is sealed in the cylinder 2, and hydraulic fluid and gas are sealed in the reservoir chamber 4 as hydraulic fluids.

[0014] 4, the valve body 51 has a fitting portion 52 that fits onto the inner periphery of one end 20 of the cylinder 2, and a cylindrical portion 53 formed on one end of the fitting portion 52. The cylindrical portion 53 has a larger outer diameter than the fitting portion 52, and defines the third chamber 21 inside. An annular abutment surface 54 (see FIG. 1) is formed between the fitting portion 52 and the cylindrical portion 53 of the valve body 51, against which the end face of the one end of the cylinder 2 abuts.

[0015] An end face 55 (sealing surface) on one end side of the cylindrical portion 53 of the valve body 51 abuts against an annular sealing surface 34 (see FIG. 3 ) formed on the bottom portion 33 of the base cap 31. The sealing surface 34 of the base cap 31 and the end face 55 of the valve body 51 are arranged on a plane perpendicular to the center line of the shock absorber 1 (hereinafter referred to as the "axis-perpendicular plane of the shock absorber 1"). Note that one end side end 20 of the cylinder 2 is positioned coaxially with respect to the center line of the shock absorber 1 because the end on one end side of the cylindrical portion 53 of the valve body 51 is guided toward the center by an inner cylindrical surface 36 formed on the outer periphery of the sealing surface 34 of the bottom portion 33 of the base cap 31.

[0016] 1 to 3, the valve body 51 has a groove 56 that extends radially (the "up-and-down direction" in FIG. 2) on the end surface 55 of the cylindrical portion 53. The groove 56 forms a flow path 57 with a rectangular cross section that connects the third chamber 21 to the reservoir chamber 4 between the end surface 55 (sealing surface) of the cylindrical portion 53 and the sealing surface 34 of the base cap 31. The groove 56 is located at the lower end of the cylindrical portion 53 and is formed symmetrically with respect to a vertical plane that includes the center line of the shock absorber 1.

[0017] The valve body 51 has a notch 58 formed on the inner peripheral side of the end surface 55 of the cylindrical portion 53. The outer peripheral portion of the notch 58 on the end surface 55 of the cylindrical portion 53 abuts against the sealing surface 34 of the base cap 31. The notch 58 is located at the upper end of the cylindrical portion 53 (diametrically opposite to the groove 56) and is formed symmetrically with respect to a vertical plane including the center line of the shock absorber 1. In the first embodiment, the notch 58 has a radial length that is the same as the width of the groove 56 (the length in the left-right direction in FIG. 2 ) and an axial length that is the same as the depth of the groove 56 (the length in the left-right direction in FIG. 1 ).

[0018] As shown in FIGS. 2 to 4 , the valve body 51 has a protrusion 59 that protrudes diagonally downward and radially outward. The protrusion 59 is located close to a side surface 60 on one side (the "left side" in FIG. 2 ) of the groove 56. One end face (reference numeral omitted) of the protrusion 59 is located flush with the end face 55 of the cylindrical portion 53. On the other hand, the base cap 31 has a recess 35 into which the protrusion 59 of the valve body 51 fits. When the shock absorber 1 is installed sideways, the groove 56 and the protrusion 59 of the valve body 51 are located at a position lower than the liquid level S1 (see FIG. 2 ) of the hydraulic fluid sealed in the reservoir chamber 4. In the first embodiment, the groove 56 and the protrusion 59 are located at a position lower than a horizontal plane L0 including the center line of the shock absorber 1.

[0019] In the shock absorber 1 described above, during the extension stroke of the piston rod 10, the hydraulic fluid equivalent to the volume of the piston rod 10 withdrawn from the cylinder 2 flows from the reservoir chamber 4 to the second chamber 2B via the groove 56 (flow path 57) formed in the valve body 51, the third chamber 21, the passage 46 formed in the valve body 51, and the check valve 48. On the other hand, during the compression stroke of the piston rod 10, the hydraulic fluid equivalent to the volume of the piston rod 10 entering the cylinder 2 flows from the second chamber 2B to the reservoir chamber 4 via the passage 47 formed in the valve body 51, the relief valve 49, the third chamber 21, and the groove 56 (flow path 57) formed in the valve body 51.

[0020] Here, conventional shock absorbers used pins to position the base cap and the valve body, so it was necessary to ensure sufficient thickness to machine the pin fitting holes in the base cap and the valve body, which resulted in the problem of an increased overall length.

[0021] In contrast, in the first embodiment, a convex portion 59 that protrudes radially outward is formed at one end of the valve body 51 (second cylinder bottom member), and the convex portion 59 is fitted into a recess 35 formed in the bottom 33 of the base cap 31 (first cylinder bottom).In other words, the convex portion 59 that protrudes radially outward from the valve body 51 is accommodated in the recess 35 formed in the base cap 31, thereby positioning the valve body 51 circumferentially (in the direction of rotation about the center line of the shock absorber 1) relative to the base cap 31.

[0022] According to the first embodiment, pins for circumferentially positioning the valve body 51 relative to the base cap 31 are not required, so there is no need to ensure a wall thickness (axial length) for machining fitting holes for the pins in the base cap 31 and the valve body 51, and in particular, it is possible to reduce the wall thickness of the bottom portion 33 of the base cap 31. Therefore, in the first embodiment, the overall length (basic length) can be shortened compared to conventional shock absorbers. Furthermore, the effort and time required to machine positioning pins in the base cap 31 can be saved, thereby reducing manufacturing costs.

[0023] In the first embodiment, the positioning structure between the valve body 51 and the base cap 31 and the sealing structure between the valve body 51 and the base cap 31 are integrated. In other words, the convex portion 59 (positioning structure) and the end face 55 (sealing structure) of the cylindrical portion 53 can be formed on the valve body 51 by press molding, and the concave portion 35 (positioning structure) and the sealing surface 34 (sealing structure) can be formed on the base cap 31 by press molding, which makes it possible to further reduce manufacturing costs.

[0024] In the first embodiment, a notch 58 of the same width as the groove 56 is formed in the end face 55 of the valve body 51. In other words, the notch 58 is formed so that the opening area on the end face 55 (sealing surface) of the valve body 51 is approximately equal to the opening area of ​​the groove 56, and the notch 58 is positioned on the radially opposite side of the groove 56. This makes it possible to equalize the pressure acting on the end face 55 (sealing surface) of the valve body 51, improve the sealing performance between the base cap 31 and the valve body 51, and stabilize the axial force acting on the cylinder 2.

[0025] In the first embodiment, the groove portion 56 (flow path 57) and the convex portion 59 (positioning mechanism in the rotational direction) of the valve body 51 are positioned at a position lower than the liquid level S1 of the working fluid sealed in the reservoir chamber 4 (on the ground side when the shock absorber 1 is attached to the railway vehicle), thereby preventing air from entering the cylinder 2 from the reservoir chamber 4 through the gap between the groove portion 56 and the convex portion 59 and the recess 35.

[0026] Second Embodiment Next, a second embodiment will be described with reference to Figures 5 to 7. Note that the same names and symbols are used for parts common to the first embodiment, and duplicated descriptions will be omitted.

[0027] The valve body 51 has a protrusion 59 that protrudes radially outward and vertically downward. On the other hand, the base cap 31 has a recess 35 (see FIG. 6 ) into which the protrusion 59 of the valve body 51 is fitted. The valve body 51 has grooves 65, 66 that extend radially on the end face 55 of the cylindrical portion 53. The grooves 65, 66 are arranged on both circumferential sides of the end face 55 of the cylindrical portion 53, sandwiching the protrusion 59 therebetween. The grooves 65, 66 are formed symmetrically with respect to a vertical plane that includes the center line of the shock absorber 1.

[0028] The grooves 65, 66 form flow paths 67, 68 with a rectangular cross section that connect the third chamber 21 to the reservoir chamber 4 between the end face 55 (sealing surface) of the cylindrical portion 53 and the sealing surface 34 of the base cap 31. The grooves 65, 66 and the protrusion 59 of the valve body 51 are positioned lower than the liquid level S1 (see FIG. 5 ) of the hydraulic fluid sealed in the reservoir chamber 4 when the shock absorber 1 is installed sideways. In the second embodiment, the grooves 65, 66 and the protrusion 59 are positioned lower than a horizontal plane L0 that includes the center line of the shock absorber 1. In the second embodiment, the same effects as those of the first embodiment can be obtained.

[0029] Third Embodiment Next, a third embodiment will be described with reference to Figures 8 to 10. Note that the same names and symbols are used for parts common to the first embodiment, and duplicated descriptions will be omitted.

[0030] In the first embodiment described above, a convex portion 59 that protrudes radially outward is formed on the valve body 51, and a concave portion into which the convex portion 59 is fitted is formed on the base cap 31, thereby positioning the valve body 51 in the circumferential direction (the rotational direction around the center line of the shock absorber 1) relative to the base cap 31.

[0031] In contrast to this, in the third embodiment, a protrusion 71 that abuts against the side surface 60 of the groove 56 formed in the valve body 51 (second cylinder bottom member) and a protrusion 72 that abuts against the side surface 61 of the groove 56 formed in the valve body 51 are formed on the sealing surface 34 of the bottom 33 of the base cap 31 (first cylinder bottom), thereby positioning the valve body 51 circumferentially (in the direction of rotation about the center line of the shock absorber 1) relative to the base cap 31.

[0032] The protrusion 71 has a rectangular cross section in a horizontal plane, and extends upward from the inner cylindrical surface 36 of the base cap 31 in parallel to a vertical plane including the center line of the shock absorber 1. The protrusion 72 is formed symmetrically with respect to the protrusion 71, with the vertical plane including the center line of the shock absorber 1 as the plane of symmetry. In other words, the protrusions 71, 72 are arranged as a pair in the groove 56 of the valve body 51, spaced apart in the groove width direction of the groove 56 (the "left-right direction" in FIG. 8 ).

[0033] The third embodiment can achieve the same effects as the first embodiment. Furthermore, the third embodiment can eliminate the protrusion 59 formed on the valve body 51 in the first embodiment. This eliminates the need to form the recess 35 extending radially outward on the other end (inner side) surface of the bottom portion 33 of the base cap 31. This makes it possible to reduce the inner diameter of the cylindrical portion 32 of the base cap 31, and therefore the outer diameter of the base shell 3, thereby enabling the shock absorber 1 to be made smaller.

[0034] The above-described embodiment can be configured as follows. As shown in Fig. 11, a protrusion 41 formed by press molding on the outside of the bottom 33 of the base cap 31 (first cylinder bottom) can be used as a guide when the shock absorber 1 is attached sideways to a railway vehicle. This prevents the shock absorber 1 from being attached in the wrong direction, i.e., prevents the flow paths 57, 67, 68 from being positioned higher than the liquid level S1 (see Fig. 2) of the hydraulic fluid sealed in the reservoir chamber 4.

[0035] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0036] This application claims priority from Japanese Patent Application No. 2023-100130, filed June 19, 2023. The entire disclosure of Japanese Patent Application No. 2023-100130, filed June 19, 2023, including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety.

[0037] 1 shock absorber, 2 cylinder (second cylinder), 2A first chamber, 2B second chamber, 3 base shell (bottom of first cylinder), 4 reservoir chamber, 5 end portion on one end side (first end portion), 10 piston rod, 11 end portion on one end side (first end portion), 12 end portion on the other end side (second end portion), 21 third chamber, 35 recessed portion, 59 protruding portion

Claims

1. A shock absorber, the shock absorber comprising: a cylindrical first cylinder; a cylindrical second cylinder disposed within the first cylinder; a reservoir chamber formed between the first cylinder and the second cylinder; a first cylinder bottom formed at a first end of the first cylinder; a piston movably inserted into the second cylinder and partitioning the interior of the second cylinder into a first chamber and a second chamber; a piston rod having a first end attached to the piston and a second end extending outside the second cylinder; a second cylinder bottom member disposed between the first cylinder bottom and the second cylinder, the second cylinder bottom member forming a third chamber between the second cylinder bottom member and the first cylinder bottom; a convex portion formed on the second cylinder bottom member and protruding radially outward; a concave portion formed on the first cylinder bottom for receiving the convex portion; a groove portion formed on a contact surface of the second cylinder bottom member with the first cylinder bottom for communicating the reservoir chamber and the third chamber; wherein the groove portion is disposed close to the convex portion; when the shock absorber is disposed horizontally, the convex portion and the groove portion are disposed on the ground side with respect to the center line of the shock absorber; the convex portion and the groove portion are disposed at a position lower than the liquid level of the working fluid enclosed in the reservoir chamber. A shock absorber characterized by this.

2. A shock absorber, the shock absorber comprising: a cylindrical first cylinder; a cylindrical second cylinder disposed within the first cylinder; a reservoir chamber formed between the first cylinder and the second cylinder; a first cylinder bottom formed at a first end of the first cylinder; a piston movably inserted into the second cylinder and partitioning the interior of the second cylinder into a first chamber and a second chamber; a piston rod having a first end attached to the piston and a second end extending outside the second cylinder; a second cylinder bottom member disposed between the first cylinder bottom and the second cylinder, the second cylinder bottom member forming a third chamber between the second cylinder bottom member and the first cylinder bottom; a convex portion formed on the second cylinder bottom member and protruding radially outward; a concave portion formed on the first cylinder bottom for receiving the convex portion; a groove portion formed on a contact surface of the second cylinder bottom member with the first cylinder bottom for communicating the reservoir chamber and the third chamber; wherein the shock absorber has the following features: The shock absorber is characterized in that the groove portion is disposed on both circumferential sides of the convex portion with respect to the bottom member of the second cylinder. **Claim 3**: A shock absorber, comprising: A cylindrical first cylinder; A cylindrical second cylinder disposed within the first cylinder; A reservoir chamber formed between the first cylinder and the second cylinder; A first cylinder bottom formed at a first end of the first cylinder; A piston movably inserted into the second cylinder and partitioning the interior of the second cylinder into a first chamber and a second chamber; A piston rod having a first end attached to the piston and a second end extending outside the second cylinder; A second cylinder bottom member disposed between the first cylinder bottom and the second cylinder, the second cylinder bottom member forming a third chamber between the second cylinder bottom member and the first cylinder bottom; A convex portion formed on the second cylinder bottom member and protruding radially outward; A concave portion formed on the first cylinder bottom for accommodating the convex portion; A groove portion formed on a contact surface of the second cylinder bottom member with the first cylinder bottom and communicating the reservoir chamber and the third chamber; And having: The second cylinder bottom member has a notch portion formed by notching the seal surface and the radially inner surface; The shock absorber is characterized in that the notch portion is disposed opposite to the groove portion in the radial direction. **Claim 4** A shock absorber, comprising: A cylindrical first cylinder; A cylindrical second cylinder disposed within the first cylinder; A reservoir chamber formed between the first cylinder and the second cylinder; A first cylinder bottom formed at a first end of the first cylinder; A piston movably inserted into the second cylinder and partitioning the interior of the second cylinder into a first chamber and a second chamber; A piston rod having a first end attached to the piston and a second end extending outside the second cylinder; A second cylinder bottom member disposed between the first cylinder bottom and the second cylinder, the second cylinder bottom member forming a third chamber between the second cylinder bottom member and the first cylinder bottom; A groove portion formed on a seal surface of the second cylinder bottom member with the first cylinder bottom and communicating the reservoir chamber and the third chamber; A protruding portion formed on the first cylinder bottom and protruding inside the groove portion; And comprising a shock absorber characterized by the above.