Cylindrical vibration isolator for railway vehicle

Abstract

To provide a cylindrical vibration isolator for a railway vehicle having a novel structure which can obtain a spring characteristic required for the railway vehicle while solving a problem of a non-adhesion type such as noise and the lowering of durability.SOLUTION: In a cylindrical vibration isolator 10 for a railway vehicle in which an inner shaft member 12 and an outer shaft member 14 are connected to each other by cylindrical connection rubber 16, the connection rubber 16 firmly adheres to an external peripheral face of the inner shaft member 12 and an internal peripheral face of the outer cylinder member 14, a pair of slits 40, 40 extending in a circumferential direction and penetrating in an axial direction are formed at both sides in a radial direction with the inner shaft member 12 sandwiched therebetween at an external peripheral end part of the connection rubber 16, a circumferential length of each slit 40 is set longer than a circumferential length of the connection rubber 16 between the circumferential directions of the pair of slits 40, 40, and bulged parts 32, 32 protruding to an external periphery toward the pair of slits 40, 40 are partially provided in the axial direction at an adhesion portion of the connection rubber 16 of the inner shaft member 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cylindrical vibration isolation device for use in railway vehicles. [Background technology]

[0002] Conventionally, cylindrical vibration-isolating devices have been used in bogies of railway vehicles, etc. As disclosed in, for example, JP 2007-139100 A (Patent Document 1), a cylindrical vibration-isolating device has a structure in which an inner shaft member (pin 8) and an outer cylindrical member (outer cylinder 7) are connected to each other by a connecting rubber (rubber cylinder 9). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-139100 A Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, cylindrical vibration-isolating devices for railway vehicles are required to have hard spring characteristics during acceleration and deceleration when the input load is large, and soft spring characteristics during normal running when the input load is small. In order to meet such required spring characteristics, Patent Document 1 proposes a non-bonded cylindrical vibration-isolating device in which the inner shaft member and the connecting rubber are not bonded and a gap is formed between the inner shaft member and the connecting rubber. As a result, the cylindrical vibration-isolating device of Patent Document 1 can obtain different spring characteristics when the radial displacement of the inner shaft member and the outer cylindrical member is large and when it is small.

[0005] However, when a gap is formed between the inner shaft member and the connecting rubber, there is a risk that foreign matter such as sand, dust, water, etc. may enter the gap, which may cause problems such as abnormal noise and erosion of the inner shaft member. In particular, as disclosed in Patent Document 1, the gap is formed by utilizing the thermal contraction of the connecting rubber after molding, so that it is narrow in width, and it is difficult to apply anti-rust treatment such as painting to the outer circumferential surface of the inner shaft member exposed in the gap after molding of the connecting rubber. Therefore, it was thought that the inner shaft member would easily rust when water penetrated, and its durability would decrease. In addition, when used in cold regions, there was a risk that water that entered the gap would freeze and expand, affecting the spring characteristics.

[0006] The problem to be solved by the present invention is to provide a cylindrical vibration-damping device for railway vehicles having a new structure that can solve the problems associated with non-adhesive types as described above while achieving the spring characteristics required for railway vehicles. [Means for solving the problem]

[0007] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely illustrative and may be combined with one another as appropriate, and the multiple components described in each embodiment may be recognized and used independently as far as possible, and may also be combined with any of the components described in another embodiment as appropriate. As a result, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0008] The first aspect is a cylindrical vibration-damping device for railway vehicles in which an inner shaft member and an outer cylindrical member are connected to each other by a cylindrical connecting rubber, the connecting rubber being fixed to the outer peripheral surface of the inner shaft member and the inner peripheral surface of the outer cylindrical member, the outer peripheral end of the connecting rubber having a pair of slits extending circumferentially and penetrating in the axial direction formed on both radial sides of the inner shaft member, the circumferential length of each of the slits being longer than the circumferential length of the connecting rubber between the circumferential direction of the pair of slits, and the fixed portion of the connecting rubber on the inner shaft member is partially provided with a bulge portion in the axial direction protruding outwardly toward the pair of slits.

[0009] In a cylindrical vibration-damping device constructed in accordance with this embodiment, the connecting rubber is fixed to the inner shaft member and the outer cylindrical member, so that foreign matter such as dust or water cannot enter between the connecting rubber and the inner shaft member and the outer cylindrical member, thereby avoiding problems such as abnormal noise and erosion of the inner shaft member and outer cylindrical member.

[0010] Since the connecting rubber has a pair of slits formed on both radial sides of the inner shaft member, low spring characteristics are realized when a small load is input, in which the relative displacement between the inner shaft member and the outer cylindrical member is small, and high spring characteristics are realized when a large load is input, in which the relative displacement between the inner shaft member and the outer cylindrical member is large, in the radial direction in which the pair of slits are arranged. In particular, since the circumferential length of the slits is longer than the circumferential length of the connecting rubber between the slits, the compression spring and shear spring of the connecting rubber are set small with respect to the input in the radial direction in which the pair of slits are arranged, and the low spring characteristics are more advantageously realized when a small load is input.

[0011] Since the inner shaft member has a bulge portion that protrudes toward the pair of slits, the thickness dimension of the connecting rubber is reduced in the radial direction in which the pair of slits are arranged, and when the opposing inner surfaces of the slits abut against each other in the radial direction due to the input of a large load, the compression spring constant of the thin-walled connecting rubber becomes large, and hard spring characteristics are exhibited.

[0012] Furthermore, the inner shaft member has a bulge in the axial direction at the portion where the connecting rubber is fixed, and there is a portion where the connecting rubber is fixed that has no bulge in the axial direction. This allows the connecting rubber to be thick in the portion of the inner shaft member where no bulge is provided, and ensures the free length of the connecting rubber in the radial direction, thereby improving the durability of the connecting rubber, etc. Even if such a thick portion of the connecting rubber is provided, when a large load is input, a hard spring characteristic can be obtained in the radial direction where the pair of slits are arranged, due to compression of the thin connecting rubber fixed to the protruding tip surface of the bulge.

[0013] It is preferable that the bulge be provided at the axial middle of the portion of the connecting rubber attached to the inner shaft member, and that the connecting rubber be thickened at both axial ends of the portion attached to the inner shaft member. This ensures a wide free surface at the axial ends of the connecting rubber, where distortion is likely to concentrate during elastic deformation of the connecting rubber, and thus improves the durability of the connecting rubber.

[0014] In a second aspect, in the cylindrical vibration-damping device described in the first aspect, the slit has an expanding shape that widens radially toward the openings on both axial sides.

[0015] With a cylindrical vibration-damping device constructed in accordance with this embodiment, if foreign matter such as sand, dust, water, or wear debris from the connecting rubber enters the slit, the tapered inner surface of the slit, which expands axially outward, makes it easy for the foreign matter to be expelled to the outside.

[0016] In a third aspect, in the cylindrical vibration-damping device described in the first or second aspect, the inner surface of the outer cylindrical member is covered with a cushioning rubber layer that is integrally formed with the connecting rubber and constitutes the wall surface on the outer peripheral side of the slit.

[0017] According to the cylindrical vibration-isolating device constructed according to this embodiment, the inner peripheral surface of the outer cylindrical member is covered and protected by the buffer rubber layer, thereby ensuring the corrosion resistance of the outer cylindrical member. In addition, when the inner surface of the slit abuts against the inner surface of the slit, the elasticity of the buffer rubber layer is expected to reduce the impact noise. In addition, the buffer rubber layer in this embodiment is made thin enough to be negligible in terms of vibration-isolating properties, and the slit is located at the outer peripheral end of the connecting rubber.

[0018] A fourth aspect is a cylindrical vibration-damping device described in any one of the first to third aspects, in which the bulge portions are provided in a pair protruding radially on both sides toward the pair of slits.

[0019] According to the cylindrical vibration isolation device constructed according to this aspect, in the radial direction in which the pair of bulges protrude, stiff spring characteristics are realized when a large load is applied, in which the relative displacement between the inner shaft member and the outer cylindrical member is large. Also, in the radial direction perpendicular to the protruding direction of the pair of bulges, the thickness dimension of the connecting rubber is increased, and the shear spring constant in the radial direction in which the pair of slits are arranged is reduced, thereby realizing softer spring characteristics when a small load is applied.

[0020] The fifth aspect is a cylindrical vibration-damping device described in the fourth aspect, wherein, in a radial direction perpendicular to the protruding direction of the pair of bulges, the outer peripheral surface of the fixed portion of the connecting rubber in the inner shaft member is composed of a pair of flat surfaces.

[0021] In the cylindrical vibration isolation device constructed according to this embodiment, a large radial distance is ensured between the inner shaft member and the outer cylindrical member in the radial direction where the pair of flat surfaces are provided, so that the radial free length of the connecting rubber can be made longer in the portion connecting the inner shaft member and the outer cylindrical member, thereby reducing the shear spring constant of the connecting rubber and improving its durability.

[0022] A sixth aspect is a cylindrical vibration-damping device according to any one of the first to fifth aspects, wherein the bulging portion has a vertical cross-sectional shape that is arc-shaped.

[0023] In a cylindrical vibration-damping device constructed in accordance with this embodiment, the surface of the bulge is formed as a curved surface with an arc-shaped cross-section without corners, thereby distributing stress in the connecting rubber fixed to the surface of the bulge.

[0024] Furthermore, when a prying force is applied between the inner shaft member and the outer tubular member, the shear spring component becomes more dominant in the connecting rubber, making it possible to achieve low spring force.

[0025] A seventh aspect is a cylindrical vibration-damping device described in any one of the first to sixth aspects, wherein, at an axial position where the bulge is provided, the circumferential length of a 90-degree region around the central axis of the inner shank in the radial direction in which the pair of slits are located is longer than the circumferential length of a 90-degree region around the central axis of the inner shank in a radial direction perpendicular to the radial direction in which the pair of slits are located.

[0026] According to a cylindrical vibration-damping device constructed in accordance with this embodiment, the portion of the connecting rubber that constitutes the inner surface of the slit can be fixed to the inner shaft member with a large fixing area, thereby achieving great fixing strength of that portion of the connecting rubber to the inner shaft member.

[0027] In an eighth aspect, in the cylindrical vibration-damping device according to any one of the first to seventh aspects, a wear reduction portion that reduces wear of the connecting rubber is provided within the slit.

[0028] In a cylindrical vibration-damping device constructed in accordance with this embodiment, by providing a wear reduction section, which can be achieved, for example, by applying a lubricant to the inner surface of the slit or by placing a foam or the like inside the slit that does not affect the spring characteristics, wear of the connecting rubber on the inner surface of the slit can be suppressed, thereby preventing damage to the connecting rubber and stabilizing the spring characteristics over the long term.

[0029] A ninth aspect is a cylindrical vibration-damping device described in any one of the first to eighth aspects, wherein the portion of the connecting rubber located circumferentially between the pair of slits is a portion to be cut, and when the connecting rubber is installed in a railway vehicle and in use, the portion to be cut is cut to separate the inner rubber fixed to the inner shaft member and the outer rubber fixed to the outer cylindrical member.

[0030] With a cylindrical vibration-damping device constructed in accordance with this embodiment, when attached to a railway vehicle and in use, the intended cutting portion is cut and the connecting rubber is separated into inner and outer rubber that are independent of each other, thereby more advantageously achieving low spring characteristics when the relative radial displacement between the inner shaft member and the outer cylindrical member is small.

[0031] In addition, when the cylindrical vibration isolator is in a standalone state before being attached to a railway vehicle, the inner and outer rubber are integrally connected by the section to be cut, and the inner shaft member and the outer cylindrical member are interconnected by the connecting rubber. This makes it possible to handle the cylindrical vibration isolator as a whole before use, which makes it easier to transport and store, for example.

[0032] In addition, the portion to be cut may be cut, for example, by carrying out cutting work while the cylindrical vibration-damping device is attached to a railway vehicle, or it may be designed to break due to input during use without any special cutting work being carried out.

[0033] A tenth aspect is a cylindrical vibration-damping device described in any one of the first to ninth aspects, in which an intermediate member is fixed to the connecting rubber, extending circumferentially between the inner shaft member and the outer cylindrical member in the radial direction.

[0034] In the cylindrical vibration isolation device constructed according to this embodiment, the spring characteristics can be tuned by providing an intermediate member. That is, for example, the end of the connecting rubber on the slit side is restrained by the intermediate member, and the intermediate member limits the radial thickness of the connecting rubber, thereby achieving high springiness when the relative displacement between the inner shaft member and the outer cylindrical member is large in the radial direction where the pair of slits are arranged.

[0035] An eleventh aspect is the cylindrical vibration-damping device according to the tenth aspect, wherein the intermediate member is disposed adjacent to the inner periphery of the slit.

[0036] In a cylindrical vibration-damping device constructed in accordance with this embodiment, the intermediate member is positioned adjacent to the inner circumference of the slit, so that there is no rubber between the opposing surfaces of the intermediate member and the outer cylindrical member that would affect the spring characteristics, and the hard spring characteristics are quickly exhibited when the intermediate member and the outer cylindrical member come into direct or indirect contact with each other.

[0037] A twelfth aspect is a cylindrical vibration-damping device described in the tenth or eleventh aspect, in which the intermediate member is composed of a pair of plate-shaped members, and the pair of plate-shaped members are arranged on both sides in the same radial direction as the pair of slits.

[0038] In a cylindrical vibration-damping device constructed in accordance with this embodiment, the intermediate member composed of a pair of plate-shaped members can achieve both high spring characteristics in the radial direction in which the pair of slits are arranged and sufficient free length of the connecting rubber in the radial direction perpendicular to the arrangement direction of the pair of slits.

[0039] A thirteenth aspect is a cylindrical vibration-damping device for railway vehicles in which an inner shaft member and an outer tubular member are connected to each other by a cylindrical connecting rubber, the connecting rubber being fixed to the outer peripheral surface of the inner shaft member and the inner peripheral surface of the outer tubular member, the connecting rubber having a pair of slits extending circumferentially and penetrating in the axial direction formed on both radial sides of the inner shaft member, the portion of the connecting rubber located circumferentially between the pair of slits being a portion to be cut, and when installed in a railway vehicle and in use, the portion to be cut is cut to separate the inner rubber fixed to the inner shaft member and the outer rubber fixed to the outer tubular member.

[0040] With a cylindrical vibration-damping device constructed in accordance with this embodiment, when the device is attached to a railway vehicle and in use, the intended cutting portion is cut and the connecting rubber is separated into inner and outer rubber that are independent of each other, thereby more advantageously achieving low spring characteristics when the displacement of the inner shaft member and the outer cylindrical member is small.

[0041] In addition, when the cylindrical vibration isolator is in a standalone state before being attached to a railway vehicle, the inner and outer rubber are integrally connected by the section to be cut, and the inner shaft member and the outer cylindrical member are interconnected by the connecting rubber. This makes it possible to handle the cylindrical vibration isolator as a whole before use, which makes it easier to transport and store, for example.

[0042] In addition, the portion to be cut may be cut, for example, by carrying out cutting work while the cylindrical vibration-damping device is attached to a railway vehicle, or it may be designed to break due to input during use without any special cutting work being carried out.

[0043] A fourteenth aspect is a cylindrical vibration-damping device for railway vehicles in which an inner shaft member and an outer cylindrical member are arranged internally and externally and connected to each other by a cylindrical connecting rubber, the connecting rubber being fixed to the outer peripheral surface of the inner shaft member and the inner peripheral surface of the outer cylindrical member, the outer peripheral end of the connecting rubber having a pair of slits extending circumferentially and penetrating in the axial direction formed on both radial sides of the inner shaft member, and an intermediate member extending circumferentially between the inner shaft member and the outer cylindrical member is fixed to the connecting rubber, and the intermediate member is arranged adjacent to the inner circumference of the slits.

[0044] In the cylindrical vibration isolation device constructed according to this embodiment, the spring characteristics can be tuned by providing an intermediate member. That is, for example, the end of the connecting rubber on the slit side is restrained by the intermediate member, and the intermediate member limits the radial thickness of the connecting rubber, thereby achieving high springiness when the relative displacement between the inner shaft member and the outer cylindrical member is large in the radial direction where the pair of slits are arranged.

[0045] Furthermore, by positioning the intermediate member adjacent to the inner circumference of the slit, there is no rubber between the opposing surfaces of the intermediate member and the outer tubular member that would affect the spring characteristics, and the hard spring characteristics are quickly exhibited when the intermediate member and the outer tubular member come into direct or indirect contact with each other.

[0046] A fifteenth aspect is a cylindrical vibration-damping device as described in the fourteenth aspect, in which the intermediate member is composed of a pair of plate-shaped members, and the pair of plate-shaped members are arranged on both sides in the same radial direction as the pair of slits.

[0047] In a cylindrical vibration-damping device constructed in accordance with this embodiment, the intermediate member composed of a pair of plate-shaped members can achieve both high spring characteristics in the radial direction in which the pair of slits are arranged and sufficient free length of the connecting rubber in the radial direction perpendicular to the arrangement direction of the pair of slits.

[0048] A sixteenth aspect is a cylindrical vibration-damping device according to the fourteenth or fifteenth aspect, wherein the curvature of the outer peripheral surface of the intermediate member is the same as the curvature of the inner surface on the outer peripheral side of the slit.

[0049] With a cylindrical vibration-damping device constructed in accordance with this embodiment, when the relative displacement between the inner axial member and the outer tubular member in the radial direction in which a pair of slits are arranged is large, the inner peripheral side wall portion of the slit formed by the outer peripheral surface of the intermediate member and the outer peripheral side wall portion of the slit abut over a wider circumferential range, making it easier to achieve stiff spring characteristics. Effect of the Invention

[0050] According to the present invention, in a cylindrical vibration isolation device for railway vehicles, it is possible to solve the problems associated with non-bonded types, such as abnormal noise and reduced durability, while achieving the spring characteristics required for railway vehicles. [Brief description of the drawings]

[0051] [Figure 1] FIG. 1 is a front view showing a cylindrical vibration isolation device for a railway vehicle according to a first embodiment of the present invention; [Diagram 2] Cross-sectional view of Fig. 1 along line II-II [Diagram 3] III-III cross section of Figure 2 [Figure 4] IV-IV cross section of Figure 2 [Diagram 5] A graph showing the spring characteristics in the left-right direction of the cylindrical vibration isolator shown in FIG. [Figure 6] FIG. 11 is a front view showing a cylindrical vibration isolation device for a railway vehicle according to a second embodiment of the present invention. [Figure 7] Cross-sectional view of FIG. 6 taken along the line VII-VII [Figure 8] FIG. 11 is a front view showing a cylindrical vibration isolation device for a railway vehicle according to a third embodiment of the present invention. [Figure 9] FIG. 11 is a front view showing a cylindrical vibration isolation device for a railway vehicle according to a fourth embodiment of the present invention; [Figure 10] FIG. 10 is a cross-sectional view of the cylindrical vibration-damping device shown in FIG. 9, which corresponds to the cross section XX in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0053] 1 to 4 show a railway vehicle bushing 10 (hereinafter referred to as bushing 10) as a first embodiment of a cylindrical vibration-damping device for railway vehicles according to the present invention. The bushing 10 has a structure in which an inner shaft member 12 and an outer cylindrical member 14 are connected to each other by a connecting rubber 16. In the following description, as a general rule, the up-down direction refers to the up-down direction in Fig. 1, the left-right direction refers to the left-right direction in Fig. 1, and the front-rear direction refers to the left-right direction in Fig. 2.

[0054] The inner shaft member 12 is a hard member formed of, for example, metal or fiber-reinforced synthetic resin, and has a structure in which a fixing portion 20 is integrally formed between a pair of mounting portions 18, 18. The mounting portion 18 is plate-shaped with a pair of flat mounting surfaces 22, 22, and has a bolt hole 24 penetrating in the plate thickness direction. The mounting portion 18 has a side curved in an arc shape and extends in the circumferential direction. The structure of the inner shaft member 12 is not limited to the one specifically exemplified in the embodiment. For example, a solid rod-shaped inner shaft member may be adopted, and the solid rod-shaped inner shaft member may have a non-through screw hole opening on one end face in the axial direction instead of the bolt hole 24. In addition, for example, when the inner shaft member is fixed to the car body or the bogie by a means such as press-fitting, the bolt hole 24 or the screw hole may not be provided. In addition, for example, the mounting portion 18 of the inner shaft member may have one or more mounting surfaces 22.

[0055] The fixing portion 20 is a portion to which the connecting rubber 16 is fixed as described later, and is a pair of cylindrical portions 26, 26 whose both axial ends have a substantially constant diameter dimension over the entire circumference, and an intermediate portion 28 is provided between the cylindrical portions 26, 26. The intermediate portion 28 and the cylindrical portions 26, 26 are integrally formed, and have mutually different cross-sectional shapes. The outer diameter dimension of the cylindrical portion 26 is slightly larger than the maximum outer diameter dimension of the mounting portion 18, and a step surface 30 that extends perpendicular to the front-rear direction is formed over the entire circumference at the boundary between the cylindrical portion 26 and the mounting portion 18.

[0056] As shown by the dashed lines in FIG. 1, the intermediate portion 28 is provided with a pair of bulging portions 32, 32 that protrude in the left-right direction. The bulging portions 32 protrude outward in the left-right direction beyond the outer circumferential surface of the cylindrical portion 26. The bulging portions 32 have a cross-sectional shape of a tip end surface 34 that is an arc-shaped curve extending in the circumferential direction concentrically with the outer circumferential surface of the cylindrical portion 26. In the intermediate portion 28 of this embodiment, the width dimension in the up-down direction perpendicular to the protruding direction of the pair of bulging portions 32, 32 is approximately the same as the diameter of the cylindrical portion 26. The tip end surface 34 of the bulging portion 32 is curved in an arc shape in the vertical cross section shown in FIG. 3, and extends continuously in the circumferential direction in an approximately constant arc-shaped curve. The vertical cross section refers to a cross section including the central axis of the bush 10 that extends in the front-rear direction, as shown in FIG. 2 and FIG. 3.

[0057] The circumferential end surface of the bulging portion 32 is a flat surface 36 that spreads perpendicularly to the up-down direction. Therefore, in the radial direction perpendicular to the protruding direction of the bulging portions 32, 32, the outer circumferential surface of the intermediate portion 28 of the inner shaft member 12 is composed of a pair of flat surfaces 36, 36. The tip surface 34 of the bulging portion 32 and the flat surface 36 form a corner portion 38 at the intersection of the tip surface 34 and the flat surface 36 of the bulging portion 32. The corner portion 38 may be formed by directly connecting the tip surface 34 of the bulging portion 32 and the flat surface 36 without smoothly continuing through a curved surface, but may also be formed smoothly continuing to form a substantially angular shape through a curved surface with a small radius of curvature, for example, and this can prevent the occurrence of cracks in the connecting rubber 16 at the portion where the connecting rubber 16 is fixed to the corner portion 38.

[0058] At the axial position where the bulging portions 32, 32 are provided, the circumferential length of the 90-degree regions (upper and lower 90-degree regions Y, Y in FIG. 4) around the central axis of the inner shaft member 12 in the radial direction (upper and lower direction) perpendicular to the radial direction where the slits 40, 40 are located is shorter than the circumferential length of the 90-degree regions (left and right 90-degree regions X, X in FIG. 4) around the central axis of the inner shaft member 12 in the radial direction (left and right direction) where the slits 40, 40 are located. In this embodiment, at the axial position where the bulging portions 32, 32 are provided, the outer circumferential surface of the inner shaft member 12 in the left and right 90-degree regions X, X is composed of the tip surfaces 34, 34 of the bulging portions 32, 32, and the outer circumferential surface of the inner shaft member 12 in the upper and lower 90-degree regions Y, Y is composed of flat surfaces 36, 36. The slits 40, which will be described later, extend over the entire circumferential length of the left and right 90-degree regions X, and have their circumferential ends extending into the upper and lower 90-degree regions Y.

[0059] The outer cylindrical member 14, like the inner shaft member 12, is a hard member made of metal, fiber-reinforced synthetic resin, or the like, and has a thin-walled, large-diameter, generally cylindrical shape. The inner diameter of the outer cylindrical member 14 is larger than the maximum outer diameter of the fixing portion 20 of the inner shaft member 12, and can be inserted outside the fixing portion 20 while being spaced from the outer periphery. The axial length of the outer cylindrical member 14 is larger than the axial length of the fixing portion 20 of the inner shaft member 12. However, the axial length of the outer cylindrical member 14 may be smaller than the axial length of the fixing portion 20 of the inner shaft member 12.

[0060] The outer tubular member 14 is disposed in a state of being inserted onto the fixing portion 20 of the inner axial member 12, and the fixing portion 20 of the inner axial member 12 and the outer tubular member 14 are elastically connected by a connecting rubber 16. The connecting rubber 16 is generally cylindrical in shape, and its inner peripheral surface is vulcanized and bonded to the outer peripheral surface of the fixing portion 20 of the inner axial member 12, and its outer peripheral surface is vulcanized and bonded to the inner peripheral surface of the outer tubular member 14. In this embodiment, the connecting rubber 16 is formed as an integral vulcanization molded product including the inner axial member 12 and the outer tubular member 14. In addition, the step surface 30 of the inner axial member 12 defines the end position of the cavity in the molding die for the connecting rubber 16, and the connecting rubber 16 is fixed only to the outer peripheral surface of the fixing portion 20 of the inner axial member 12 without being fixed to the mounting portion 18. The surfaces on both sides of the connecting rubber 16 in the axial direction have a tapered shape that inclines axially inward toward the outer periphery. In addition, the inner shaft member 12 and the outer cylindrical member 14 are preferably subjected to pretreatment such as painting, forming an adhesive layer, plating, etc., for the purpose of preventing rust and improving adhesive strength before the connecting rubber 16 is molded, thereby preventing exposure to the outside and improving durability.

[0061] The inner peripheral end of the connecting rubber 16 has an axial center portion fixed to an outer peripheral surface including tip faces 34, 34 of a pair of bulging portions 32, 32, and both axial ends fixed to the outer peripheral surfaces of a pair of cylindrical portions 26, 26. In other words, the bulging portions 32, 32 are provided in a part of the axial direction at the fixing portion of the connecting rubber 16 to the inner shaft member 12. Since both axial end portions of the connecting rubber 16 are fixed to the inner shaft member 12 at positions axially offset from the bulging portions 32, the thickness is ensured without being further thinned by the bulging portions 32.

[0062] A pair of slits 40, 40 are formed in the connecting rubber 16. The slits 40 are formed on the outer peripheral end of the connecting rubber 16, extend in the circumferential direction of the connecting rubber 16, and penetrate the connecting rubber 16 in the axial direction. The slits 40 are formed on both the left and right sides of the inner shaft member 12. In this embodiment, the pair of slits 40, 40 are symmetrical to each other, and have substantially the same radial width dimension and circumferential length dimension.

[0063] A pair of rubber arm portions 42, 42 are formed between the circumferential ends of the pair of slits 40, 40. The rubber arm portion 42 is a part of the connecting rubber 16, and connects the inner shaft member 12 and the outer cylindrical member 14 to each other in the radial direction (up and down direction). The circumferential length dimension of the slit 40 is larger than the circumferential width dimension of the rubber arm portion 42. The circumferential length dimension of the slit 40 is preferably 1.25 times or more the circumferential width dimension of the rubber arm portion 42, and more preferably 1.5 times or more.

[0064] On the outer periphery of the slit 40, a cushioning rubber layer 44 is provided which constitutes the wall surface on the outer periphery of the slit 40. The cushioning rubber layer 44 is integrally provided with the connecting rubber 16 to constitute the outer periphery end of the connecting rubber 16, and is fixed to the inner periphery of the outer tubular member 14. The cushioning rubber layer 44 covers almost the entire inner periphery of the outer tubular member 14 except for both ends in the axial direction. The cushioning rubber layer 44 is made thin enough so as not to affect the spring characteristics of the bush 10 in the left-right direction.

[0065] A stopper rubber 46 is provided on the inner periphery of the slit 40, constituting the wall surface on the inner periphery of the slit 40. The stopper rubber 46 is provided integrally with the connecting rubber 16, constituting the inner periphery end of the connecting rubber 16, and is fixed to the inner shaft member 12 at the tip surface 34 of the bulging portion 32 that protrudes toward the slit 40. The stopper rubber 46 is thicker than the buffer rubber layer 44, and contributes to the spring characteristics of the bush 10 in the left-right direction when it abuts against the outer cylindrical member 14.

[0066] In this embodiment, the circumferential length of the outer circumferential surface of the inner shaft member 12 is longer in the left and right 90-degree regions X, X than in the top and bottom 90-degree regions Y, Y. This makes it possible to secure a large fixing area of ​​the stopper rubber 46 to the inner shaft member 12, and therefore the stopper rubber 46 can be firmly fixed to the inner shaft member 12.

[0067] The slit 40 is formed in an expanded shape that becomes wider in the radial direction from the center in the axial direction toward the outside, and the opposing inner surface 48a on the inner periphery side of the slit 40 is a tapered surface that inclines from the axial center toward the inner periphery toward both axial outsides, while the opposing inner surface 48b on the outer periphery side of the slit 40 is a tapered surface that inclines from the axial center toward the outer periphery toward both axial outsides. As a result, foreign matter such as wear debris of the connecting rubber 16 generated by the opposing inner surfaces 48a, 48b of the slit 40 sliding against each other is easily discharged to the outside by the taper of the opposing inner surfaces 48a, 48b. In particular, the opposing inner surfaces 48a, 48b are repeatedly displaced and deformed by vibration input in the left-right direction, so that the discharge action of foreign matter is effectively exerted. The opposing inner surface 48a on the inner periphery side of the slit 40 is formed of the stopper rubber 46 in the circumferential center portion, and the opposing inner surface 48b on the outer periphery side of the slit 40 is formed of the cushion rubber layer 44.

[0068] The radial width dimension of the slit 40 is smaller than the distance from the tip of the bulging portion 32 of the inner shaft member 12 to the outer cylindrical member 14, preferably smaller than half the radial distance between the cylindrical portion 26 of the inner shaft member 12 and the outer cylindrical member 14, and more preferably smaller than ¼ the radial distance between the cylindrical portion 26 and the outer cylindrical member 14. Both circumferential ends of the slit 40 are each approximately semicircular when viewed in the front-rear direction. Therefore, both circumferential ends of the slit 40 are radially narrower toward the outside in the circumferential direction.

[0069] A friction reducing portion may be provided inside the slit 40. The friction reducing portion reduces frictional resistance when the opposing inner surfaces 48a, 48b of the slit 40 slide against each other, thereby suppressing wear of the connecting rubber 16. Note that the friction reducing portion may be, for example, a lubricant layer that covers at least one of the surfaces of the opposing inner surfaces 48a, 48b, or a sponge-like foam that is inserted between the opposing inner surfaces 48a, 48b.

[0070] The bush 10 thus constructed is disposed at the end of a connecting rod that connects the car body and bogie of a railway vehicle, and the inner shaft member 12 and the outer tubular member 14 are attached to either one of the car body or the bogie and the connecting rod. Specifically, for example, the bush 10 connects the car body or the bogie and the connecting rod in a vibration-proof manner by having the outer tubular member 14 press-fitted and fixed to mounting tubular portions provided at both ends of the connecting rod, and the inner shaft member 12 is bolted to the car body or the bogie using the bolt holes 24. When the bush 10 is attached to the connecting rod, the bush 10 may be provided on only one side of the connecting rod, but it is preferable that the bush 10 be provided at both ends of the connecting rod.

[0071] When the bush 10 is mounted on a railway vehicle, vibration in the left-right direction, which is the axial direction of the connecting rod, is input as the main load between the inner axial member 12 and the outer tubular member 14. Here, the spring constant of the bush 10 changes significantly between an area where the relative displacement between the inner axial member 12 and the outer tubular member 14 in the left-right direction is small and an area where the relative displacement between the inner axial member 12 and the outer tubular member 14 in the left-right direction is large.

[0072] That is, in the small displacement region A where the relative displacement (deflection) in the left-right direction between the inner shaft member 12 and the outer cylindrical member 14 is small, the inclination angle of the load-deflection diagram shown in Fig. 5 is small, and the spring constant is set small. In particular, in the small displacement region A, the opposing inner surfaces 48a, 48b of the slit 40 are kept apart, so that the shear spring of the rubber arm portions 42, 42 becomes dominant in the spring characteristics of the bushing 10.

[0073] Both circumferential ends of the slit 40 extend outward beyond the bulging portion 32 on both the top and bottom sides, and the entire tip surface 34 of the bulging portion 32 is disposed facing the slit 40. Therefore, in the small displacement region A, the connecting rubber 16 is less likely to be compressed in the left-right direction between the opposing surfaces of the tip surface 34 of the bulging portion 32 and the inner circumferential surface of the outer tubular member 14, and soft spring characteristics can be obtained due to the shear spring properties of the rubber arm portions 42, 42.

[0074] In the bushing 10, the circumferential width dimension of the rubber arm portion 42 between the circumferential slits 40, 40 is made smaller than the circumferential length dimension of the slits 40. By making the left-right width dimension of the rubber arm portion 42 smaller in this manner, the shear spring constant of the rubber arm portion 42 is made smaller, and low spring characteristics in the small displacement region A in FIG.

[0075] In addition, the bulging portions 32, 32 of the inner shaft member 12 protrude in a radial direction perpendicular to the rubber arm portions 42, 42, and the fixing surfaces of the rubber arm portions 42, 42 on the inner shaft member 12 are flat surfaces 36, 36. This ensures that the free length of the rubber arm portions 42, 42 in the radial direction is long with excellent space efficiency, and the shear spring constant of the rubber arm portions 42, 42 is set smaller, more advantageously achieving low spring characteristics in the small displacement region A.

[0076] On the other hand, in the large displacement region B where the relative displacement (deflection) between the inner shaft member 12 and the outer cylindrical member 14 in the left-right direction is larger than that in the small displacement region A, the inclination angle of the load-deflection diagram shown in Fig. 5 is large, and the spring constant is set to be large. In particular, in the large displacement region B, the opposing inner surfaces 48a, 48b of the slit 40 come into contact with each other, and the stopper rubber 46 of the connecting rubber 16 covering the tip surface 34 of the bulging portion 32 comes into contact with the inner surface of the outer cylindrical member 14 via the buffer rubber layer 44 and is compressed, so that the compression spring of the stopper rubber 46 becomes dominant in the spring characteristics of the bush 10. In this embodiment, since the inner peripheral surface of the outer cylindrical member 14 is covered with the buffer rubber layer 44, the impact sound generated when the tip surface 34 of the bulging portion 32 covered with the stopper rubber 46 comes into contact with the inner peripheral surface of the outer cylindrical member 14 is reduced by the buffer rubber layer 44.

[0077] In the bush 10, the bulge 32 is provided in the axial center of the fixing portion 20 of the inner shaft member 12, and both end portions of the fixing portion 20 are cylindrical portions 26 having a smaller diameter in the left-right direction than the portions where the bulges 32, 32 are formed. This makes it possible to ensure rubber volume at both axial end portions of the connecting rubber 16 where distortion due to deformation is likely to concentrate, thereby improving the durability of the connecting rubber 16. In particular, in this embodiment, the axial end faces of the connecting rubber 16 are tapered, thereby ensuring a large free surface area at the axial end faces of the connecting rubber 16, and improving the durability of the connecting rubber 16 is more effectively achieved. Moreover, in the vertical cross section shown in FIG. 3, the bulge 32 has an arc-shaped cross section tapered toward the upper or lower protruding tip side, and therefore the surface of the bulge 32 is inclined in the same direction as the axial surface of the connecting rubber 16. Therefore, even if the axial end faces of the connecting rubber 16 are tapered, it is easy to ensure the thickness of the connecting rubber 16 on both axial outsides of the bulge 32.

[0078] 4, the tip surface 34 of the bulge 32 is formed in an arc shape that extends with a substantially constant curvature over the entire surface, and is connected to the upper and lower side surfaces by forming corners 38. This makes it possible to make the thickness dimension of the stopper rubber 46 that covers the tip surface 34 of the bulge 32 substantially constant over the entire circumferential direction, and to realize the stiff spring characteristics of the compression spring of the stopper rubber 46 with efficient space utilization.

[0079] The radial width of the slit 40 is substantially constant in the circumferential middle portion and narrows at both circumferential end portions, so that in the large displacement region B, the opposing inner surfaces 48a, 48b of the slit 40 abut against each other over the entirety, and the slit 40 is essentially eliminated, advantageously exhibiting high spring characteristics.

[0080] 5, the region where the relative displacement between the inner shaft member 12 and the outer cylindrical member 14 in the left-right direction is less than 3b is the small displacement region A, and the region where the relative displacement is 3b or more is the large displacement region B. Therefore, in the bush 10 of this embodiment, the inner shaft member 12 and the outer cylindrical member 14 are displaced in the left-right direction by about 3b, so that the opposing inner surfaces 48a, 48b of the slit 40 come into contact with each other. However, the magnitude of the displacement (deflection) that is the boundary between the small displacement region A and the large displacement region B is not particularly limited, and is set appropriately according to the required spring characteristics.

[0081] The bush 10 mounted on a railway vehicle may be subjected to inputs other than vibration loads in the lateral direction. For example, input in the lateral twisting direction may cause the inner shaft member 12 and the outer tubular member 14 to tilt relative to each other in the lateral direction. In this case, as shown in Fig. 3, the tip surface 34 of the bulge 32 is formed in an arc shape with the center of curvature at the center of the inner shaft member 12. This suppresses compression of the connecting rubber 16 by the bulge 32 when the inner shaft member 12 and the outer tubular member 14 are twisted to the lateral direction, as compared to bulges having other cross-sectional shapes such as trapezoidal cross-sections, and low spring characteristics can be obtained.

[0082] 6 and 7 show a railway vehicle bushing 50 as a second embodiment of the present invention. The bushing 50 has a structure in which a pair of slits 52, 52 are formed in the connecting rubber 16. In the following explanation, the same reference numerals are used in the drawings to designate the same members and parts as those in the first embodiment, and explanations thereof will be omitted.

[0083] The slit 52 of this embodiment has a longer circumferential length than the slit 40 of the first embodiment, and the circumferential ends of the pair of slits 52, 52 are close to each other. The portion of the connecting rubber 16 located between the circumferential ends of the pair of slits 52, 52 is a cut-off portion 54, 54 that is thin-walled in the circumferential direction. The cut-off portion 54 extends over the entire axial direction of the connecting rubber 16, and connects the inner shaft member 12 and the outer tubular member 14 to each other in the up-down direction by separating the slits 52, 52 from each other in the circumferential direction. The cut-off portion 54 of this embodiment has a circumferential thickness dimension that is minimum at the center in the radial direction, but may have a constant thickness dimension over the entire radial direction, for example, or may be thinnest at the inner peripheral end or the outer peripheral end.

[0084] The cut-off portion 54 connects the inner shaft member 12 and the outer tubular member 14 to each other as shown in Figs. 6 and 7 when the bush 50 is in a state of being a single bush before being mounted on a railway vehicle. On the other hand, when the bush 50 is used in a state of being mounted on a railway vehicle, the cut-off portion 54 is cut in the circumferential direction, and the connecting rubber 16 is separated into an inner circumferential rubber 56 on the inner circumferential side of the slit 52 and the cut portion of the cut-off portion 54, and an outer circumferential rubber 58 (buffer rubber layer 44) on the outer circumferential side. Therefore, when the bush 50 is in a state of being mounted on a railway vehicle, the connecting rubber 16 does not connect the inner shaft member 12 and the outer tubular member 14, and the inner shaft member 12 and the outer tubular member 14 are independent from each other. However, since the inner shaft member 12 and the outer tubular member 14 are attached to either the car body or the bogie of the railway vehicle, they are positioned relative to each other even after the cut-off portion 54 is cut.

[0085] The cut-off portion 54 may be cut by a blade after the bush 50 is mounted on the railcar, or may be automatically broken by the input of a load to the bush 50 during use without the need for a cutting operation. If the cut-off portion 54 is cut in the cutting process, the cut state is stabilized, and stable vibration-proof characteristics and improved reliability are achieved. If the cutting process is omitted and the cut-off portion 54 is broken by the input load, the number of work steps can be reduced. Note that, in the case where the cut-off portion 54 is automatically broken by the input of a load during use, it is desirable for it to break immediately after the start of use, but it may also break after a certain period of use, and the timing of the breakage is not particularly limited.

[0086] In this embodiment, the slits 52, 52 are formed on the outer peripheral end of the connecting rubber 16 and extend circumferentially along the outer tubular member 14, and the portions to be cut 54, 54 are disposed in close proximity to the outer tubular member 14. Therefore, when the portions to be cut 54 are broken by an input load, it is expected that the cutting manner of the portions to be cut 54 will be stabilized by the restraining force of the outer tubular member 14.

[0087] In this way, since the portion to be cut 54 of the bushing 50 is cut when in use, the spring constant in the small displacement region A becomes smaller, and the vibration insulation effect against small amplitude vibration is more effectively exerted.

[0088] In a structure in which the connecting rubber 16 is cut at the intended cutting portion 54 when the bush 50 is in use, there is no need to ensure a free length in the radial direction of the rubber arm portions 42, 42 as in the first embodiment in order to achieve low spring characteristics in the small displacement region A. Therefore, even if a bulge portion 62 that protrudes outward is provided continuously with a constant cross-sectional shape around the entire circumference as in a railway vehicle bush 60 as a third embodiment shown in Fig. 8, a low spring characteristic in the small displacement region A can be obtained. In the bush 10 of the first embodiment, a bulge portion 62 provided around the entire circumference may be used instead of the pair of bulges 32, 32.

[0089] 9 and 10 show a railway vehicle bushing 70 as a fourth embodiment of the present invention. The bushing 70 has a structure in which an intermediate member 72 extending circumferentially between the inner shaft member 12 and the outer cylindrical member 14 in the radial direction is fixed to the connecting rubber 16.

[0090] The intermediate member 72 is composed of a pair of plate-like members 74, 74. The plate-like member 74 is curved in an arc shape and extends in the circumferential direction, and has a length less than half the circumference in the circumferential direction. The pair of plate-like members 74, 74 are arranged opposite each other on both sides in the left and right direction where the pair of slits 40, 40 are arranged, and are spaced apart from each other in the circumferential direction. The rubber arm portion 42 of the connecting rubber 16 in this embodiment is formed by extending in the radial direction (up and down direction) between the slits 40, 40 and the plate-like members 74, 74 in the circumferential direction. The pair of plate-like members 74, 74 are arranged symmetrically opposite each other with the same shape and size. This makes it possible for the pair of plate-like members 74, 74 to be a common part. However, the pair of plate-like members may have different shapes from each other, and for example, one plate-like member may have a longer circumferential length than the other plate-like member, and the circumferential length of one plate-like member may be more than half the circumference.

[0091] The plate-shaped member 74 extends outward in the circumferential direction beyond the bulging portion 32, and is located inside the slit 40 in the circumferential direction. However, the relationship in the circumferential length between the plate-shaped member 74 and the slit 40 is not particularly limited, and the plate-shaped member 74 may extend outward in the circumferential direction beyond the slit 40. As can be seen from this, the plate-shaped member 74 does not necessarily have to be adjacent to the slit 40 over its entire circumferential direction, as long as at least a part of it in the circumferential direction is adjacent. Similarly, the plate-shaped member 74 does not necessarily have to be adjacent to the slit 40 over its entire axial direction, as long as at least a part of it in the axial direction is adjacent.

[0092] In this embodiment, both circumferential ends of the slit 40, which is generally semicircular when viewed in the axial direction, are positioned to protrude outward in the circumferential direction from the plate-shaped member 74, but both circumferential ends of the slit 40 may be positioned circumferentially inward from both circumferential ends of the plate-shaped member 74. In this case, a relatively thick rubber may be formed on the outer circumferential surface of the plate-shaped member 74 to fill the radial gap between both circumferential ends of the slit 40 and the plate-shaped member 74, but it is not necessary to consider the effect of this rubber on the vibration-proofing characteristics.

[0093] The pair of plate-like members 74, 74 are fixed to the connecting rubber 16 at positions adjacent to the inner periphery of each of the slits 40. The plate-like member 74 extends in the circumferential direction concentrically with the slit 40 and constitutes the wall portion on the inner periphery of the slit 40. The outer periphery of the plate-like member 74 may be exposed in the slit 40 or may be covered with a thin covering rubber. When covered with a covering rubber, the covering rubber is made thin enough that it is not necessary to consider the effect on the spring characteristics of the bush 10. Therefore, in this embodiment, the opposing inner surface 48a of the slit 40 is substantially formed of the plate-like member 74.

[0094] 10, the plate-like member 74 protrudes from the axial end face of the connecting rubber 16. The plate-like member 74 has approximately the same axial length as the outer tubular member 14, but may protrude further axially outward than the outer tubular member 14, or may be located axially inward than the outer tubular member 14.

[0095] By disposing the plate-like members 74, 74 on the inner circumferential side of the slits 40, 40, the radial thickness dimension of the stopper rubber 46 covering the tip surface 34 of each bulge portion 32 is made smaller than that of the first embodiment. In this way, by providing the intermediate member 72 made of the plate-like members 74, 74 radially between the slits 40, 40 and the bulge portions 32, 32, the radial thickness dimension of the stopper rubber 46, 46 can be reduced and the spring constant of the large displacement region B can be set larger without increasing the radial width dimension of the slits 40, 40 or the protruding height dimension of the bulge portions 32, 32 in the left-right direction. In addition, since it is not necessary to increase the protruding height dimension of the bulge portions 32, 32 in the left-right direction, low spring characteristics against prying input and torsion input are maintained, and effective vibration insulation against input in the prying direction and torsion direction can be obtained.

[0096] In the inner shaft member 12 of the railway vehicle bush 70 having the intermediate member 72 (a pair of plate-like members 74, 74), the bulging portions 32, 32 may be omitted.

[0097] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the specific description. For example, the bulging portions may be provided at a plurality of positions spaced apart from each other in the axial direction in the fixing portion of the connecting rubber of the inner shaft member.

[0098] The side surface of the bulge is not necessarily limited to a flat surface, and may be, for example, a curved surface that extends continuously from the tip surface. In other words, in a cross section (a cross section perpendicular to the central axis of the inner shaft member) at the portion where the bulge is formed, the inner shaft member may be, for example, an ellipse with the protruding direction of the bulge being the long axis direction.

[0099] In addition, the specific shape of the bulge is not particularly limited, and for example, a bulge having a rectangular shape in vertical section (a section parallel to and including the central axis of the inner shaft member) may be adopted. By adopting such a bulge having a rectangular shape in vertical section, the connecting rubber (stopper rubber) fixed to the tip surface of the bulge can be made thin over a wider range in the axial direction, making it easier to realize harder spring characteristics in the large displacement region.

[0100] The width of the slit in the radial direction may vary in the circumferential direction, and for example, the spring characteristics can be adjusted by making the width of both end portions in the circumferential direction narrower than that of the central portion, which is less likely to be filled with the connecting rubber when the inner surface of the slit abuts. Also, a pair of slits may have different shapes or sizes, which makes it possible to realize different spring characteristics on both sides in the radial direction.

[0101] The portion to be cut 54 shown in the second embodiment does not necessarily need to be provided over the entire axial length, but may be provided partially in the axial direction, which is expected to facilitate the cutting operation and to facilitate breakage due to load input. When the portion to be cut 54 is provided partially in the axial direction, its axial position is not particularly limited, but for example, when the portion to be cut is cut by a cutting operation before use, it is desirable to provide it near the axial end so as to facilitate cutting, and when the portion is broken by load input during use, it is desirable to provide it in the axial center portion in consideration of the balance before cutting.

[0102] The intermediate member 72 (plate-like members 74, 74) shown in the fourth embodiment is provided concentrically with the outer cylindrical member 14, but the intermediate member 72 may be provided non-concentrically with the outer cylindrical member 14 so that, for example, the curvature of the outer peripheral surface of the intermediate member 72 (the opposing inner surface 48a on the inner peripheral side of the slit 40) and the curvature of the inner peripheral surface of the outer cylindrical member 14 (the opposing inner surface 48b on the outer peripheral side of the slit 40) are substantially the same as each other. In this way, when a large load is input, the opposing inner surfaces 48a, 48b of the slit 40 come into contact with each other substantially simultaneously over a wider range in the circumferential direction, so that the spring constant of the large displacement region B can be significantly increased compared to the spring constant of the small displacement region A. [Explanation of symbols]

[0103] 10 Railway vehicle bush (Cylindrical vibration isolation device for railway vehicles, first embodiment) 12 Inner shaft member 14 Outer cylindrical member 16 Connecting rubber 18 Mounting part 20 Fixing part 22 Mounting surface 24 Bolt holes 26 Cylindrical section 28 Middle Section 30 Step surface 32 Bulge 34 Tip surface 36 Flat surface 38 Corner 40 Slit 42 Rubber arm 44 Cushioning rubber layer 46 Stopper rubber 48a, 48b Opposing inner surface 50 Railway vehicle bush (Cylindrical vibration isolation device for railway vehicles, second embodiment) 52 Slit 54 Section to be cut 56 Inner rubber 58 Outer rubber 60 Railway vehicle bush (Third embodiment of cylindrical vibration isolation device for railway vehicles) 62 Bulge 70 Railway vehicle bush (fourth embodiment of cylindrical vibration isolation device for railway vehicles) 72 Intermediate parts 74 Plate-shaped members X Left and right 90 degree areas Y Top and bottom 90 degree areas A Small displacement region B Large displacement region

Claims

1. A cylindrical vibration isolation device for a railway vehicle, in which an inner shaft member and an outer cylindrical member are connected to each other by a cylindrical connecting rubber, the connecting rubber is fixed to an outer peripheral surface of the inner shaft member and an inner peripheral surface of the outer cylindrical member, A pair of slits extending in the circumferential direction and penetrating in the axial direction are formed on both radial sides of the inner shaft member at the outer circumferential end of the connecting rubber, A circumferential length of each of the slits is longer than a circumferential length of the connecting rubber between the pair of slits in the circumferential direction, A cylindrical vibration-damping device in which a bulge portion that protrudes outwardly toward the pair of slits is partially provided in the axial direction at the portion of the inner shaft member to which the connecting rubber is fixed.

2. 2. The cylindrical vibration-damping device according to claim 1, wherein the slits are shaped to widen radially toward openings on both axial sides.

3. 3. The cylindrical vibration-damping device according to claim 1, wherein the inner peripheral surface of the outer cylindrical member is covered with a cushioning rubber layer which is integrally formed with the connecting rubber and constitutes a wall surface on the outer peripheral side of the slit.

4. 3. The cylindrical vibration-damping device according to claim 1, wherein the bulging portion is provided in a pair protruding radially outwardly toward both sides of the pair of slits.

5. 5. The cylindrical vibration-damping device according to claim 4, wherein an outer circumferential surface of the portion of the inner shaft member to which the connecting rubber is fixed is formed of a pair of flat surfaces in a radial direction perpendicular to the protruding direction of the pair of bulging portions.

6. 3. The cylindrical vibration-damping device according to claim 1, wherein the bulging portion has a vertical cross-sectional shape that is an arc.

7. A cylindrical vibration-damping device as described in claim 1 or 2, wherein at the axial position where the bulge is provided, the circumferential length of a 90-degree region around the central axis of the inner shaft member in the radial direction in which the pair of slits are located is longer than the circumferential length of a 90-degree region around the central axis of the inner shaft member in a radial direction perpendicular to the radial direction in which the pair of slits are located.

8. 3. The cylindrical vibration-damping device according to claim 1, wherein a wear reducing portion that reduces wear of the connecting rubber is provided inside the slit.

9. 3. A cylindrical vibration-damping device as described in claim 1 or 2, wherein the portion of the connecting rubber located circumferentially between the pair of slits is defined as a portion to be cut, and when the connecting rubber is installed in a railway vehicle and in use, the portion to be cut is cut to separate the inner rubber fixed to the inner shaft member and the outer rubber fixed to the outer cylindrical member.

10. 3. The cylindrical vibration-damping device according to claim 1, wherein an intermediate member is fixed to the connecting rubber, the intermediate member extending in a circumferential direction radially between the inner shaft member and the outer cylindrical member.

11. 11. The cylindrical vibration isolation device according to claim 10, wherein the intermediate member is disposed adjacent to an inner periphery of the slit.

12. 12. The cylindrical vibration-isolating device according to claim 11, wherein the intermediate member is composed of a pair of plate-like members, the pair of plate-like members being arranged on both sides in the same radial direction as the pair of slits.

13. A cylindrical vibration isolation device for a railway vehicle, in which an inner shaft member and an outer cylindrical member are connected to each other by a cylindrical connecting rubber, the connecting rubber is fixed to an outer peripheral surface of the inner shaft member and an inner peripheral surface of the outer cylindrical member, A pair of slits extending in a circumferential direction and penetrating in an axial direction are formed in the connecting rubber on both radial sides of the inner shaft member, The portion of the connecting rubber located circumferentially between the pair of slits is designated as a portion to be cut, and when the cylindrical vibration-damping device is installed in a railway vehicle and in use, the portion to be cut is cut to separate the inner rubber fixed to the inner shaft member and the outer rubber fixed to the outer cylindrical member.

14. A cylindrical vibration isolation device for a railway vehicle, in which an inner shaft member and an outer cylindrical member are connected to each other by a cylindrical connecting rubber, the connecting rubber is fixed to an outer peripheral surface of the inner shaft member and an inner peripheral surface of the outer cylindrical member, A pair of slits extending in the circumferential direction and penetrating in the axial direction are formed on both radial sides of the inner shaft member at the outer circumferential end of the connecting rubber, An intermediate member is fixed to the connecting rubber, the intermediate member extending in a circumferential direction between the inner shaft member and the outer cylindrical member in a radial direction, The intermediate member is disposed adjacent to the inner periphery of the slit.

15. 15. The cylindrical vibration-isolating device according to claim 14, wherein the intermediate member is composed of a pair of plate-like members, the pair of plate-like members being arranged on both sides in the same radial direction as the pair of slits.

16. 16. A cylindrical vibration-damping device according to claim 14, wherein the curvature of the outer circumferential surface of the intermediate member is the same as the curvature of the inner surface on the outer circumferential side of the slit.

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