Cylindrical vibration isolation device

Abstract

To provide a cylindrical vibration-proofing device having a new structure capable of positioning with high accuracy by press-fitting an inner shaft member into an inner periphery of an inner cylinder member, and achieving durability improvement of rubber provided on the inner periphery of the inner cylinder member.SOLUTION: In a cylindrical vibration-proofing device 10 obtained by elastically connecting an inner member 12 and an outer cylindrical member 14 with a body rubber elastic body 16, the inner member 12 is configured to include an inner cylindrical member 18 and an inner shaft member 20, press-fit support rubber 32 extending from one end of an axial direction to the middle in the axial direction is provided on an inner peripheral surface of the inner cylindrical member 18, the inner shaft member 20 is press-fitted axially beyond an inner end 33 of the press-fit support rubber 32 to the middle of the inner cylindrical member 18, and an inner end surface of the inner shaft member 20 is not covered with the press-fit support rubber 32.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a cylindrical vibration-damping device that connects members to be connected in a vibration-damping manner. [Background technology]

[0002] Conventionally, cylindrical vibration-damping devices have been known that are used in power unit mounts that support automobile engines and motors, suspension bushings, etc. As shown in Japanese Patent Laid-Open No. 2021-089052 (Patent Document 1), cylindrical vibration-damping devices have a structure in which an inner member and an outer cylindrical member are connected by a main rubber elastic body.

[0003] The inner member in Patent Document 1 is constructed by rubber-pressing an inner bracket as an inner shaft member into a cylindrical inner cylindrical member. The inner cylindrical member has an inner peripheral surface that is covered with a rubber coating layer (inner coating) of a substantially constant thickness, and the inner bracket is press-fitted into the inner cylindrical member partway in the axial direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-089052 Summary of the Invention [Problem to be solved by the invention]

[0005] However, after investigations by the present inventors, the structure of Patent Document 1 had the problem that the covering rubber layer, which is the rubber used for press-fitting and compressed by the inner bracket, protrudes onto the press-fit front end surface of the inner bracket, causing the inner bracket to be pressed in the axial direction opposite to the press-fit direction, making it difficult to accurately set the axial position of the inner bracket relative to the inner tubular member. Also, if there is a compressed portion of the covering rubber layer that protrudes onto the press-fit front end surface of the inner bracket, stress is likely to concentrate in that portion, which may reduce durability.

[0006] The problem to be solved by the present invention is to provide a cylindrical vibration-damping device with a novel structure that can press-fit an inner shaft member into the inner circumference of an inner cylindrical member and position it with high precision, while also improving the durability of the press-fit rubber provided on the inner circumference of the inner cylindrical member. [Means for solving the problem]

[0007] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, 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 in which an inner member and an outer cylindrical member are elastically connected by a main rubber elastic body, and the inner member is configured to include an inner cylindrical member and an inner shaft member, and a press-fit support rubber is provided on the inner peripheral surface of the inner cylindrical member, extending in the axial direction from one end to the middle in the axial direction, and the inner shaft member is press-fitted in the axial direction beyond the inner end of the press-fit support rubber to the middle of the inner cylindrical member, and the press-fit support rubber covers the inner end face of the inner shaft member, A covering rubber layer extending from one end in the axial direction to the middle is fixed to the inner peripheral surface of the inner cylindrical member over the entire circumference, and a plurality of press-fit protrusions extending in the axial direction are provided in the circumferential direction on the outer peripheral surface of the inner axial member, and the inner axial member is press-fitted at the press-fit protrusions beyond the inner end of the covering rubber layer, the abutting portion of the covering rubber layer with which the press-fit protrusions abut serves as the press-fit support rubber, and rubber relief spaces extending in the axial direction are formed on both circumferential sides of the press-fit protrusions. It is something.

[0009] In a cylindrical vibration-damping device constructed in accordance with this embodiment, the inner axial member is pressed into the press-fit support rubber extending in the axial direction, thereby ensuring the press-fit fixing force of the inner axial member and dispersing the compressive stress acting on the press-fit support rubber in the axial direction, thereby achieving stable press-fit fixing force and ensuring the durability of the press-fit support rubber.

[0010] Since the inner shaft member is press-fitted beyond the inner end of the press-fit support rubber, which extends to the middle of the inner cylindrical member in the axial direction, and the press-fit support rubber does not cover the inner end face of the inner shaft member, the press-fit support rubber is less likely to exert a force pushing back (springback) on the inner shaft member in the opposite direction to the press-fitting direction, which allows the inner shaft member to be positioned accurately relative to the inner cylindrical member.

[0011] Since the press-fit support rubber does not cover the inner end surface of the inner shaft member, for example, the inner end surface of the inner shaft member can be secured as a bolt tightening surface while avoiding the rubber from getting pinched, etc. Moreover, stress is prevented from concentrating on the press-fit support rubber that protrudes from the inner end surface of the inner shaft member, and the durability of the press-fit support rubber is also secured. Furthermore, with a cylindrical vibration-damping device constructed according to this aspect, by providing press-fit protrusions on the outer peripheral surface of the inner axial member, the inner axial member can be partially press-fitted into the inner peripheral surface of the inner tubular member covered with a coating rubber layer at multiple locations in the circumferential direction. This forms rubber relief spaces that allow deformation of the press-fit support rubber between the circumferential spaces of the press-fitted portions of the inner axial member into the inner tubular member, stabilizing the press-fitting. By providing press-fit protrusions on the inner axial member, partial press-fitting at multiple locations in the circumferential direction can be achieved by the coating rubber layer provided around the entire inner peripheral surface of the inner tubular member, making it easier to ensure, for example, high adhesion strength of the coating rubber layer to the inner tubular member.

[0019] No. two The embodiment is First In the cylindrical vibration-damping device described in the embodiment, the inner shaft member is provided with a bolt insertion hole that penetrates through in the axial direction.

[0020] According to the cylindrical vibration-damping device constructed in accordance with this aspect, the inner shaft member can be attached to another member, such as a vibration-damping connection target, by means of a bolt inserted into the bolt insertion hole. [Effects of the Invention]

[0021] According to the present invention, by pressing an inner axial member into the inner circumference of an inner cylindrical member provided with a press-fit support rubber, even if the tip of the inner axial member is pressed in halfway in the axial direction and does not reach the tip of the inner cylindrical member, the inner axial member can be accurately positioned in the axial direction relative to the inner cylindrical member, and the durability of the press-fit support rubber can also be improved. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view showing a power unit mount according to a first embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view showing the power unit mount shown in FIG. 1 from a different angle. [Figure 3] Front view of the power unit mount shown in Figure 1 [Figure 4] Rear view of the power unit mount shown in Figure 1 [Figure 5] VV cross section of Figure 3 [Figure 6] VI-VI cross section of Figure 5 [Figure 7] A perspective view of the integrally vulcanized molded part that constitutes the power unit mount shown in Figure 1. [Figure 8] FIG. 8 is a perspective view showing the integrally vulcanization molded product shown in FIG. 7 from a different angle. [Figure 9] Front view of the integrally vulcanized molded product shown in Figure 7 [Figure 10] FIG. 10 is a perspective view showing a power unit mount according to a second embodiment of the present invention; [Figure 11] FIG. 11 is a perspective view showing the power unit mount shown in FIG. 10 from a different angle. [Figure 12] 12 is a cross-sectional view of the power unit mount shown in FIG. 10, which corresponds to the XII-XII cross section of FIG. 13. [Figure 13] XIII-XIII cross section of Figure 12 [Figure 14] FIG. 11 is a perspective view of an inner shaft member that constitutes the power unit mount shown in FIG. [Figure 15] A front view of the integrally vulcanized molded product that constitutes the power unit mount shown in Figure 10. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] 1 to 6 show a power unit mount 10 for an automobile as a first embodiment of a cylindrical vibration-damping device constructed in accordance with the present invention. Power unit mount 10 supports a power unit such as an engine or a motor in a vibration-damping manner, and has a structure in which an inner member 12 and an outer cylindrical member 14 are connected by a main rubber elastic body 16. In the following description, as a general rule, the up-down direction refers to the up-down direction in Fig. 3, the left-right direction refers to the left-right direction in Fig. 3, and the front-rear direction refers to the left-right direction in Fig. 5.

[0025] The inner member 12 is configured to include an inner tubular member 18 and an inner shaft member 20. The inner tubular member 18 is formed, for example, from metal and has a substantially cylindrical shape with an inner hole 22 penetrating in the front-rear direction. Like the inner tubular member 18, the inner shaft member 20 is also formed, for example, from metal. The inner shaft member 20 may be, for example, a solid column, but in this embodiment, it has a substantially cylindrical shape extending in the front-rear direction and has a bolt insertion hole 24 formed on the central axis that penetrates in the axial direction. The bolt insertion hole 24 has a substantially circular cross section, but may also have a substantially elliptical cross section, for example. The inner shaft member 20 has a length dimension larger than that of the inner tubular member 18.

[0026] The outer cylindrical member 14 has a generally cylindrical shape with a thin wall and a large diameter that extends in the front-rear direction, and is made of, for example, metal. The outer cylindrical member 14 has a shorter axial length than the inner cylindrical member 18.

[0027] The outer cylindrical member 14 is fitted onto the inner cylindrical member 18 while being spaced apart in the radial direction, and the inner cylindrical member 18 and the outer cylindrical member 14 are connected by a main rubber elastic body 16. The main rubber elastic body 16 is of a generally cylindrical shape, and its inner peripheral surface is vulcanization bonded to the outer peripheral surface of the inner cylindrical member 18, and its outer peripheral surface is vulcanization bonded to the inner peripheral surface of the outer cylindrical member 14. The main rubber elastic body 16 is formed as an integrally vulcanization molded product 26 including the inner cylindrical member 18 and the outer cylindrical member 14. In the integrally vulcanization molded product 26, the inner cylindrical member 18 protrudes outward in both axial directions relative to the outer cylindrical member 14. The intermediate portion of the main rubber elastic body 16 between the portion (inner peripheral end) attached to the inner cylindrical member 18 and the portion (outer peripheral end) attached to the outer cylindrical member 14 has an axial dimension smaller than that of the inner cylindrical member 18 and the outer cylindrical member 14, and both axial end faces are located axially outward of both axial end faces of the inner cylindrical member 18 and the outer cylindrical member 14.

[0028] The main rubber elastic body 16 is provided with a pair of hollow portions 28, 28. The hollow portions 28 are holes that penetrate in the axial direction and have a flat cross-sectional shape in which the vertical dimension is smaller than the horizontal dimension. The hollow portions 28 are provided on both the upper and lower sides of the inner tubular member 18, thereby making the spring constant of the main rubber elastic body 16 in the vertical direction smaller than the spring constant in the horizontal direction. The hollow portions 28 extend outward on both sides beyond the inner tubular member 18 in the horizontal direction.

[0029] A coating rubber layer 30 is provided on the inner peripheral surface of the inner tubular member 18. The coating rubber layer 30 has a substantially cylindrical shape and is formed so as to completely cover the inner peripheral surface of the inner tubular member 18. The coating rubber layer 30 is integrally continuous with the main rubber elastic body 16 on both axially outer sides of the inner tubular member 18. It is also possible to provide radial through-holes in the inner tubular member 18, and to integrally form the main rubber elastic body 16 and the coating rubber layer 30 through the through-holes. Although not shown in the figure, both axial ends of the inner tubular member 18 are exposed from the rubber at multiple locations on the circumference, and the inner tubular member 18 is held in the molding die at these exposed portions when molding the main rubber elastic body 16 and the coating rubber layer 30.

[0030] As shown in Figures 7 to 9, a plurality of press-fit support rubbers 32 are integrally formed on the covering rubber layer 30 provided on the inner peripheral surface of the inner cylindrical member 18. The press-fit support rubbers 32 are formed to protrude from the covering rubber layer 30 toward the inner peripheral surface. The press-fit support rubbers 32 have a tapered cross-sectional shape that narrows in the circumferential direction toward the protruding tip. The protruding tip surface of the press-fit support rubber 32 is a curved surface that widens in the circumferential direction. The press-fit support rubber 32 has a circumferential width dimension w of the protruding tip that is larger than a protruding height dimension h. The press-fit support rubber 32 extends in the axial direction from one axial end (rear end) of the inner cylindrical member 18 to the middle in the axial direction, but not to the other axial end (front end), and an inner end 33 is located in the middle in the axial direction of the inner cylindrical member 18. The press-fit support rubber 32 has an inner end 33 located on the other axial side beyond the axial center of the inner tubular member 18, and preferably has an axial length dimension that is ¾ or more of the axial length dimension of the inner tubular member 18. The press-fit support rubber 32 extends linearly and without inclination in the axial direction.

[0031] In this embodiment, the press-fit support rubbers 32 are provided at multiple locations in the circumferential direction. It is desirable that the multiple press-fit support rubbers 32 be arranged approximately evenly in the circumferential direction of the inner cylindrical member 18. Specifically, for example, four press-fit support rubbers 32, 32, 32, 32 are arranged approximately evenly in the circumferential direction, with press-fit support rubbers 32 provided on both the upper and lower sides and the left and right sides. The multiple press-fit support rubbers 32 are arranged spaced apart from each other in the circumferential direction, and the circumferential width dimension W of the base ends of the press-fit support rubbers 32 is smaller than the distance D between the base ends of adjacent press-fit support rubbers 32, 32 in the circumferential direction.

[0032] An inner shaft member 20 is attached to the integrally vulcanization-molded product 26 having such a structure. The inner shaft member 20 is inserted into the inner periphery of the inner tubular member 18 covered with the coating rubber layer 30, and is press-fitted into the inner peripheries of the four press-fit support rubbers 32. That is, the outer periphery of the inner shaft member 20, indicated by the two-dot chain line in FIG. 9, has a larger diameter than an imaginary cylindrical surface including the protruding tip surface of the press-fit support rubber 32, and a smaller diameter than an imaginary cylindrical surface including the inner periphery of the coating rubber layer 30. Therefore, when the inner shaft member 20 is inserted into the inner hole 22 of the inner tubular member 18, the inner shaft member 20 is press-fitted into the inner periphery of the press-fit support rubbers 32 at four circumferential positions, as shown in FIG. 6. As a result, the inner shaft member 20 is sandwiched and supported by the press-fit support rubbers 32, 32 that face each other in the vertical and horizontal directions, and the inner shaft member 20 is positioned and fixed to the inner cylindrical member 18 to form the inner member 12 of this embodiment. Note that the size of the compression allowance of the press-fit support rubber 32 due to the press-fitting of the inner shaft member 20, the size of the contact area of ​​the press-fit support rubber 32 with the inner shaft member 20, etc. are merely examples and are set appropriately based on the size of the fixing force required for the input load, for example.

[0033] The inner shaft member 20 is attached to the inner cylindrical member 18 not by direct metal press-fitting into the inner cylindrical member 18, but by rubber press-fitting via a press-fit support rubber 32. This prevents press-fitting defects due to galling and the like that can easily occur with metal press-fitting, and also achieves good productivity by improving the press-fitting speed, elimination of burr removal, tolerance for dimensional errors, and the like.

[0034] The inner shaft member 20 has a portion press-fitted into the press-fit support rubber 32 that extends continuously and linearly in the axial direction with a constant outer circumferential surface shape. The inner shaft member 20 of this embodiment has a constant outer circumferential surface shape over the entire axial length.

[0035] As shown in Figure 6, in a portion circumferentially separated from the press-fit support rubber 32, the inner shaft member 20 is disposed apart from the inner circumference of the covering rubber layer 30, and a rubber relief void 34 is formed on the outer circumference side of the inner shaft member 20. The rubber relief void 34 extends linearly in the axial direction and is formed in an axially penetrating state. The inner surface of the outer peripheral wall of the rubber relief void 34 is formed by the inner peripheral surface of the covering rubber layer 30, and the side walls on both sides in the circumferential direction are each formed by the press-fit support rubber 32, 32. The rubber relief void 34 ensures the free surfaces of the covering rubber layer 30 and the press-fit support rubber 32, which are provided integrally.

[0036] The provision of such rubber relief voids 34 allows the press-fit support rubber 32 to bulge and deform on both sides in the circumferential direction due to radial compression caused by the press-fitting of the inner shaft member 20. Therefore, the spring characteristics of the press-fit support rubber 32 can be adjusted with a large degree of freedom by the rubber relief voids 34, enabling the press-fit support rubber 32 to stably support the inner shaft member 20. Even when the inner shaft member 20 is press-fitted, the circumferential width dimension of the base end of the press-fit support rubber 32 is made smaller than the distance between the base ends of the press-fit support rubbers 32, 32 adjacent in the circumferential direction (the circumferential width dimension at the outer peripheral ends of the rubber relief voids 34).

[0037] 5, one axial end of the inner axial member 20 protrudes axially outward beyond the inner cylindrical member 18. The other axial end of the inner axial member 20 is located axially more inward than the other axial end of the inner cylindrical member 18. As a result, the axial centers of the inner axial member 20 and the inner cylindrical member 18 are offset from each other in the axial direction. An accommodation space 36 is formed on the inner periphery of the inner cylindrical member 18 on the other axial side of the inner axial member 20.

[0038] In this embodiment, the inner cylindrical member 18 protrudes on both axial sides relative to the outer cylindrical member 14, and the inner shaft member 20 protrudes on one axial side (in FIG. 5) relative to the inner cylindrical member 18. The end face of the inner shaft member 20 on the other axial side protrudes slightly outward from the outer cylindrical member 14 in Fig. 5, but it can also be set at a position that is set axially inward relative to the end face of the outer cylindrical member 14 on the other axial side. Also, in Fig. 5, the axial length of the inner shaft member 20 is longer than that of the inner cylindrical member 18, but it can also be set shorter than that of the inner cylindrical member 18.

[0039] The inner shaft member 20 protrudes outward in the axial direction beyond both axial ends of the press-fit support rubber 32, and the axial end faces of the inner shaft member 20 are not covered with the press-fit support rubber 32. In particular, the inner end 33, which is the other axial end of the press-fit support rubber 32, is located in the axial middle of the inner cylindrical member 18, and the inner end 33 of the inner shaft member 20 is located on the other axial side beyond the press-fit support rubber 32. Therefore, the inner end 33 of the inner shaft member 20 is disposed away from the inner periphery of the coating rubber layer 30, and the other axial end face of the inner shaft member 20 (the inner end face, which is the other axial end face of the inner end 33) is not covered with the coating rubber layer 30 and the press-fit support rubber 32. In this embodiment, the protruding dimension of the inner shaft member 20 toward one axial side relative to the press-fit support rubber 32 is larger than the protruding dimension toward the other axial side, but the protruding dimensions may be smaller on one side than on the other side, or may be the same.

[0040] 5, the power unit mount 10 constructed as described above is attached to the vehicle body 40 by threading bolts 38 inserted into the bolt insertion holes 24 of the inner shaft member 20 into the vehicle body 40. The outer cylindrical member 14 is also attached to the power unit (not shown) via an outer bracket 42. In this way, the power unit mount 10 is interposed between the vehicle body 40 and the power unit, and connects the power unit and the vehicle body 40 together in a vibration-damping manner.

[0041] The head 44 of the bolt 38 is inserted into the accommodating cavity 36 and overlaps the other axial end face of the inner axial member 20. This reduces the amount by which the head 44 protrudes from the inner tubular member 18 in the axial direction, making it possible to prevent interference between the head 44 of the bolt 38 and other vehicle components. Note that in this embodiment, a portion of the head 44 of the bolt 38 protrudes from the accommodating cavity 36, but the axial dimension of the accommodating cavity 36 may be increased, for example, so that the entire head 44 is accommodated in the accommodating cavity 36.

[0042] When a vibration load is input between the inner member 12 and the outer tubular member 14 while the vehicle is fitted with the device, a vibration-damping effect is achieved by the elastic deformation of the main rubber elastic body 16. In this embodiment, the spring ratios in the vertical and horizontal directions are adjusted by the hollow portions 28, 28, so that a vibration-insulating effect is achieved against vibration input in the vertical direction, and a high damping effect is achieved against vibration input in the horizontal direction.

[0043] The inner shaft member 20 is firmly positioned relative to the inner cylindrical member 18 by being pressed into the press-fit support rubbers 32, 32, 32, 32, and the inner shaft member 20 forms the inner member 12 integrally without being displaced relative to the inner cylindrical member 18 when a vibration load is input.

[0044] In this embodiment, as shown in Fig. 9, both circumferential side surfaces of the press-fit support rubber 32 are inclined toward each other so that the circumferential dimension decreases toward the inner circumferential side (the protruding direction), and this inclination direction is maintained even when the inner shaft member 20 is press-fitted (Fig. 6). Therefore, the press-fit support rubber 32 having such inclined circumferential side surfaces can efficiently ensure high circumferential connecting spring rigidity compared to, for example, cases in which both circumferential side surfaces are parallel to each other or both circumferential side surfaces are inclined inversely so that the circumferential dimension increases toward the inner circumferential side. Furthermore, radial compressive deformation occurs efficiently at the circumferential end portions of the press-fit support rubber 32, suppressing collapse-like deformation and thereby suppressing local tensile stress and shear stress, thereby improving durability and load-bearing performance.

[0045] In the above-described power unit mount 10, the inner shaft member can be selected from a variety of different structures while using the common integrally vulcanization molded product 26. That is, a variety of inner shaft members with different mounting structures to the vehicle body 40, such as inner shaft members with different shapes and sizes of the bolt insertion holes 24, or solid inner shaft members having fastening portions for the vehicle body 40 at their axial ends, are prepared by forming them with an outer circumferential surface shape that has a common press-fit surface. Then, by combining an inner shaft member appropriately selected from the plurality of types of inner shaft members according to the mounting structure on the vehicle body 40 side with a separately prepared integrally vulcanization molded product 26, a variety of power unit mounts with different mounting structures to the vehicle body 40 can be obtained using the common integrally vulcanization molded product 26.

[0046] 10 to 13 show a power unit mount 50 as a second embodiment of the present invention. The power unit mount 50 has a structure in which an inner member 52 and an outer tubular member 14 are connected by a main rubber elastic body 16, and an inner shaft member 56 is press-fitted into an inner tubular member 18 provided on an integrally vulcanization-molded product 54 of the main rubber elastic body 16. In the following explanation, members and parts that are substantially the same as those in the first embodiment are given the same reference numerals in the figures, and explanations thereof will be omitted.

[0047] As shown in FIG. 14 , the inner shaft member 56 is generally cylindrical and includes a bolt insertion hole 24 that penetrates axially on the central axis, as well as a plurality of press-fit protrusions 58 that protrude from the outer circumferential surface. The press-fit protrusions 58 protrude radially outward from the inner shaft member 56. The press-fit protrusions 58 are tapered so that their circumferential width decreases toward the protruding tip. The press-fit protrusions 58 are provided at multiple locations in the circumferential direction, and are preferably evenly spaced in the circumferential direction. In this embodiment, four press-fit protrusions 58 are provided on both the top and bottom and on both the left and right sides.

[0048] As shown in FIGS. 12, 13, and 15, the integrally vulcanization-molded product 54 includes a coating rubber layer 60 that covers the inner peripheral surface of the inner tubular member 18. As shown in FIG. 15, the coating rubber layer 60 is a cylindrical rubber layer having a substantially constant radial thickness and is fixed to the entire inner peripheral surface of the inner tubular member 18. In other words, the coating rubber layer 60 does not include the press-fit support rubber 32 that protrudes toward the inner peripheral surface, as in the first embodiment. As shown in FIG. 12, the coating rubber layer 60 is connected to the main rubber elastic body 16 on one axial outside of the inner tubular member 18 and is integrally formed with the main rubber elastic body 16. The coating rubber layer 60 does not reach the other axial end of the inner tubular member 18, but extends from one axial end of the inner tubular member 18 to the axial center. An inner end 62 of the coating rubber layer 60 is located at the axial center of the inner tubular member 18.

[0049] The inner shaft member 56 is inserted into the inner hole 22 of the inner tubular member 18 covered with the coating rubber layer 60, and is press-fitted onto the inner periphery of the coating rubber layer 60. That is, the inner shaft member 56 shown by the two-dot chain line in Fig. 15 has a virtual cylindrical surface including the protruding tip surfaces of the press-fit protrusions 58 whose diameter is larger than the inner diameter of the coating rubber layer 60, and the outer diameter of the portion outside the press-fit protrusions 58 is smaller than the inner diameter of the coating rubber layer 60. As a result, when the inner shaft member 56 is inserted into the inner periphery of the coating rubber layer 60, the four press-fit protrusions 58, 58, 58, 58 are pressed against the coating rubber layer 60 at four locations in the circumferential direction, as shown in Fig. 13, to create a press-fit state. Furthermore, between the circumferentially adjacent press-fit protrusions 58, 58, the inner shaft member 56 is spaced apart toward the inner circumferential side of the covering rubber layer 60, and a rubber relief space 66 is formed extending axially between the radially opposing surfaces of the inner shaft member 56 and the covering rubber layer 60. In this embodiment, the abutting portions of the covering rubber layer 60 where the press-fit protrusions 58, 58, 58, 58 abut are made into press-fit support rubbers 64, and the press-fit support rubbers 64 are provided at four locations in the circumferential direction. The other axial end of the press-fit support rubber 64 is located midway in the axial direction of the inner tubular member 18 and is formed by a part of the inner end 62 of the covering rubber layer 60.

[0050] 12 , one axial end of the inner shaft member 56 protrudes axially outward from the inner cylindrical member 18, and the other axial end is located more inward than the other axial end of the inner cylindrical member 18. An accommodating space 36 is provided on the inner periphery of the inner cylindrical member 18, outside the other axial end of the inner shaft member 56. The inner shaft member 56 also protrudes on both axial sides from the covering rubber layer 60. In particular, the other axial end of the inner shaft member 56 is located on the other axial side, beyond the inner end 62 of the covering rubber layer 60, which is located in the axial middle of the inner cylindrical member 18. As a result, both axial end surfaces of the inner shaft member 56 are exposed and not covered by the covering rubber layer 60, including the press-fit support rubber.

[0051] The inner shaft member 56 is spaced inward from the covering rubber layer 60 at a portion circumferentially away from the press-fit protrusions 58, and between the circumferentially adjacent press-fit protrusions 58, 58, rubber relief voids 66 are formed that extend in the axial direction between the outer circumferential surface of the inner shaft member 56 and the inner circumferential surface of the covering rubber layer 60. The rubber relief voids 66 are provided on both circumferential sides of each press-fit protrusion 58, and four rubber relief voids 66, 66, 66, 66 are arranged approximately evenly in the circumferential direction. The wall surfaces on both circumferential sides of the rubber relief voids 66 are defined by the press-fit protrusions 58, 58 of the inner shaft member 56. The provision of the rubber relief voids 66 allows the rubber to escape to both sides in the circumferential direction in response to radial compression of the covering rubber layer 60 (press-fit support rubber 64) caused by the pressing of the press-fit protrusions 58, thereby realizing adjustment of the force required to press-fit the inner shaft member 56 by adjusting the spring of the press-fit support rubber 64. Furthermore, the durability of the covering rubber layer 60 is improved by ensuring a free surface of the covering rubber layer 60 in the rubber relief voids 66.

[0052] The power unit mount 50 according to this embodiment can achieve the same effects as the first embodiment. Furthermore, by providing the press-fit protrusions 58 on the inner shaft member 56, it is possible to provide partial press-fit support rubbers 64 and rubber relief spaces 66 between the press-fit support rubbers 64, 64 at multiple locations in the circumferential direction, even if the covering rubber layer 60 is cylindrical and has a substantially constant thickness without any irregularities around the entire circumferential direction. This makes it possible to more effectively alleviate stress concentration in the covering rubber layer 60 than when a protruding press-fit support rubber is provided.

[0053] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific descriptions. For example, although it is desirable that the coating rubber layer and the press-fit support rubber be integrally formed with the main rubber elastic body 16, they may also be provided independently of the main rubber elastic body.

[0054] In the first embodiment, the multiple press-fit support rubbers 32 are integrally provided by the coating rubber layer 30, but for example, the multiple press-fit support rubbers 32 may be provided in a state where they are independent of each other in the circumferential direction. In this case, a rubber relief space 34 where the inner circumferential surface of the inner tubular member 18 is exposed may be formed between the press-fit support rubbers 32, 32 adjacent to each other in the circumferential direction.

[0055] In the above embodiment, the structure in which the inner axial member is press-fitted into the press-fit support rubber at multiple locations in the circumferential direction has been exemplified, but for example, the press-fit support rubber may be formed into a cylindrical shape that is continuous around the entire circumference of the inner circumferential surface of the inner cylindrical member, and the inner axial member may be press-fitted into the press-fit support rubber around the entire circumference. Also, even when press-fit support rubbers that extend in the axial direction at multiple locations in the circumferential direction are used, it is not necessary for all of the press-fit support rubbers to have the same cross-sectional shape, and it is also possible to tune the connecting spring characteristics of the press-fit support rubber at each axial position by varying the circumferential width dimension or radial height dimension in the axial direction. Furthermore, the axial end position of the press-fit support rubber is not limited; for example, in Figure 5 of the first embodiment, the press-fit support rubber 32 only needs to extend from the axial rear end side (right side in Figure 5) of the inner tubular member 18 toward the axial front end side (left side in Figure 5) to the axial middle portion; for example, the axial front end side of the press-fit support rubber 32 may be located axially inward (right side in Figure 5) than the axial front end side of the main rubber elastic body 16, and the axial rear end side of the press-fit support rubber 32 may also be located at the same level as or slightly inward from the end face of the inner tubular member 18.

[0056] The relative axial positions of the inner axial member 20 and the inner cylindrical member 18 are not particularly limited as long as one end of the inner axial member 20 is located in the middle of the inner cylindrical member 18. Specifically, for example, the axial end face of the inner axial member 20 located in the middle of the inner cylindrical member 18 may be located in the middle of the outer cylindrical member 14 in the axial direction. In this way, even if the inner axial member 20 is located inside the axial end of the outer cylindrical member 14, the main rubber elastic body 16 is disposed between the outer cylindrical member 14 and the inner cylindrical member 18, thereby minimizing the effects on the fixing area of ​​the main rubber elastic body 16 and the manner in which load is input to the main rubber elastic body 16. Therefore, while minimizing the effects on vibration-damping performance and durability, the axial position of the inner axial member 20 can be set with a high degree of freedom in accordance with the installation space for the cylindrical vibration-damping device and the mounting structure on the vehicle side, and the axial dimension of the accommodating space 36 can also be set with a high degree of freedom.

[0057] In the above embodiment, the outer peripheral surface of the inner shaft member extends linearly with a substantially constant shape and size over the entire axial length. However, the shape and size of the outer peripheral surface may vary at the axial end beyond the press-fit support rubber, for example, by making the axial end of the inner shaft member beyond the press-fit support rubber smaller in diameter than the press-fit portion of the inner shaft member. Even in this case, the outer peripheral surface of the press-fit portion of the inner shaft member extends linearly and continuously in the axial direction with a constant shape and size. Therefore, for example, if the axial end of the inner shaft member beyond the press-fit support rubber has a smaller diameter due to a tapered surface or a stepped surface, the press-fit support rubber does not cover the inner end surface of the inner shaft member formed by the tapered surface or stepped surface.

[0058] In the above embodiment, an example was given of a power unit mount for an automobile that provides vibration-damping support for an engine or motor, but the cylindrical vibration-damping device of the present invention can also be applied to, for example, mounts that support engine accessories, body mounts, differential mounts, and even bushings for elastically connecting arms and rods. Furthermore, the present invention originally includes each of the inventions described below in (i) to (v), and the configurations and effects thereof will be described below. The present invention provides (i) A cylindrical vibration-damping device in which an inner member and an outer cylindrical member are elastically connected by a main rubber elastic body, the inner member being configured to include an inner cylindrical member and an inner axial member, the inner peripheral surface of the inner cylindrical member being provided with a press-fit support rubber extending axially from one end to the middle in the axial direction, the inner axial member being press-fitted axially beyond the inner end of the press-fit support rubber to the middle of the inner cylindrical member, and the press-fit support rubber not covering the inner end face of the inner axial member; (ii) A cylindrical vibration-damping device according to (i), in which a plurality of the press-fit support rubbers are provided on the inner peripheral surface of the inner cylindrical member in a circumferential direction to protrude therefrom, and rubber relief spaces extending in the axial direction are formed on both circumferential sides of the press-fit support rubbers. (iii) The cylindrical vibration-damping device according to (ii), wherein the press-fit support rubber has a tapered shape that narrows in width in the circumferential direction toward the inner periphery, and the press-fit support rubber has a circumferential width dimension at the inner periphery end that is larger than the protruding height dimension toward the inner periphery. (iv) A cylindrical vibration-damping device as described in (i), in which a covering rubber layer extending from one end in the axial direction to the middle is fixed to the inner peripheral surface of the inner tubular member over the entire circumference, and a plurality of press-fit protrusions extending in the axial direction are protruded in the circumferential direction from the outer peripheral surface of the inner tubular member, the inner tubular member is press-fitted beyond the inner end of the covering rubber layer at the press-fit protrusions, the abutting portion of the covering rubber layer with the press-fit protrusions serves as the press-fit support rubber, and rubber relief spaces extending in the axial direction are formed on both circumferential sides of the press-fit protrusions. (v) A cylindrical vibration-damping device according to any one of (i) to (iv), wherein the inner shaft member is provided with a bolt insertion hole passing through in the axial direction. This includes inventions relating to: In the invention described in (i) above, the inner shaft member is press-fitted into the press-fit support rubber extending in the axial direction, thereby ensuring the press-fit fixing force of the inner shaft member and dispersing the compressive stress acting on the press-fit support rubber in the axial direction, thereby achieving a stable press-fit fixing force and ensuring the durability of the press-fit support rubber. The inner shaft member is press-fitted beyond the inner end of the press-fit support rubber, which extends to the middle of the inner cylindrical member in the axial direction, and the press-fit support rubber does not cover the inner end surface of the inner shaft member. This makes it difficult for the press-fit support rubber to exert a force pushing back against the inner shaft member in the opposite direction to the press-fitting direction (springback). Therefore, the inner shaft member can be accurately positioned relative to the inner cylindrical member. For example, because the press-fit support rubber does not cover the inner end surface of the inner shaft member, the inner end surface of the inner shaft member can be secured as a bolt tightening surface while avoiding pinching of the rubber, etc. Furthermore, stress is prevented from concentrating on the press-fit support rubber that protrudes from the inner end face of the inner shaft member, ensuring the durability of the press-fit support rubber. In the invention described in (ii) above, the rubber relief spaces provided circumferentially between the multiple press-fit support rubbers make it possible to tune the press-fit fixing force and the spring characteristics in the axis-perpendicular direction with a large degree of freedom. In the invention described in (iii) above, the tapered, wide press-fit support rubber prevents the inner shaft member from rotating due to the press-fit support rubber collapsing, thereby stably supporting the inner shaft member. In the invention described in (iv) above, by providing press-fit protrusions on the outer peripheral surface of the inner shaft member, the inner shaft member can be partially press-fitted into the inner peripheral surface of the inner tubular member covered with a coating rubber layer at multiple locations in the circumferential direction. This forms rubber relief spaces that allow deformation of the press-fit support rubber between the circumferential spaces of the press-fitted portions of the inner shaft member into the inner tubular member, stabilizing the press-fitting behavior. By providing press-fit protrusions on the inner shaft member, partial press-fitting at multiple locations in the circumferential direction can be achieved by the coating rubber layer provided around the entire inner peripheral surface of the inner tubular member, making it easier to ensure, for example, high adhesion strength of the coating rubber layer to the inner tubular member. In the invention described in (v) above, the inner shaft member can be attached to another member such as a vibration-damping connection target by means of a bolt inserted into the bolt insertion hole. [Explanation of symbols]

[0059] 10 Power unit mount (cylindrical vibration isolation device, first embodiment) 12 Inner member 14 outer cylindrical member 16 Main body rubber elastic body 18 Inner cylindrical member 20 Inner shaft member 22 Inner hole 24 bolt holes 26 Integral vulcanization molding 28 Currant Club 30 Covering rubber layer 32 Press-fit support rubber 33 Inner end 34 Rubber relief space 36 Vacant accommodation space 38 volts 40 Vehicle body 42 Outer bracket 44 Head 50 Power unit mount (cylindrical vibration isolation device, second embodiment) 52 Inner member 54 Integral vulcanization molding 56 Inner shaft member 58 Press-fit protrusion 60 Covering rubber layer 62 Inner end 64 Press-fit support rubber 66 Rubber relief space

Claims

1. A cylindrical vibration-damping device in which an inner member and an outer cylindrical member are elastically connected by a main rubber elastic body, The inner member includes an inner cylindrical member and an inner shaft member, A press-fit support rubber is provided on the inner peripheral surface of the inner cylindrical member, extending in the axial direction from one end to the middle in the axial direction, the inner shaft member is press-fitted in the axial direction beyond the inner end of the press-fit support rubber to the middle of the inner cylindrical member, so that the press-fit support rubber does not cover the inner end face of the inner shaft member, A coating rubber layer is fixed to the inner circumferential surface of the inner cylindrical member, extending from one end to the middle in the axial direction, over the entire periphery. A plurality of press-fit protrusions extending in the axial direction are provided on the outer peripheral surface of the inner shaft member in a circumferential direction, the inner shaft member is press-fitted at the press-fit protrusion beyond the inner end of the coating rubber layer, The portion of the coating rubber layer that comes into contact with the press-fit protrusion serves as the press-fit support rubber, The cylindrical vibration-damping device has rubber relief spaces extending in the axial direction formed on both circumferential sides of the press-fit protrusion.

2. 2. The cylindrical vibration-damping device according to claim 1, wherein the inner shaft member is provided with a bolt insertion hole passing through in the axial direction.

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