Cylindrical vibration isolation device

Abstract

To provide a cylindrical vibration control device of a new structure, capable of accurately positioning an outer cylinder member and a holder in an axial direction while stably exerting press-in fixing force to the holder of the outer cylinder member made of a synthetic resin.SOLUTION: A cylindrical vibration control device 10 has a structure in which an inner shaft member 12 and a synthetic resinous outer cylinder member 14 are coupled by a body robber elastic body 16. The outer cylinder member 14 has a structure in which a cylindrical portion 20 extends out in an axial direction from an inner peripheral end of an annular plate shaped flange portion 22. A press-in rubber 38 is fixed to an outer peripheral surface of the cylindrical portion 20, and an axial surface 46 on a side where the cylindrical portion 20 extends out in the flange portion 22 is exposed without being covered with the press-in rubber. At an axial end portion of the outer cylinder member 14 including the flange portion 22, a notch 24 penetrating in a diametrical direction is provided, and a coupling robber 52 coupling the body robber elastic body 16 and the press-in rubber 38 is provided on the notch 24.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a cylindrical vibration isolator applied to an engine mount or the like of an automobile.

Background Art

[0002] Conventionally, a cylindrical vibration isolator has been adopted as an engine mount, a subframe mount, a suspension bushing, etc. of an automobile. The cylindrical vibration isolator has a structure in which an inner shaft member and an outer cylinder member are connected by a main body rubber elastic body, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2015-161356 (Patent Document 1).

[0003] By the way, although the conventional outer cylinder member was made of metal, resinization of the outer cylinder member has been studied for the purpose of weight reduction of the cylindrical vibration isolator. Also in Patent Document 1, an outer cylinder member made of synthetic resin is exemplified.

[0004] However, when the outer cylinder member attached to other members such as a vehicle body by being press-fitted into a mounting hole is made of resin, it is easily plastically deformed by the continuous action of the stress due to press-fitting into the mounting hole, and there is a risk that the press-fitting reaction force decreases due to sagging of the outer cylinder member.

[0005] Therefore, in Patent Document 1, press-fitting rubber is provided on the outer peripheral surface of the outer cylinder member, and by exerting the fixing force of the outer cylinder member against the mounting hole by the elasticity of the press-fitting rubber, it is made difficult for the sagging of the resin-made outer cylinder member to affect the fixing force due to press-fitting into the mounting hole.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the structure of Patent Document 1, since the surface of the flange portion provided on the outer cylindrical member is covered with a covering rubber that integrally connects the press-fit rubber and the main rubber elastic body, it was conceivable that variations in the axial relative position between the outer cylindrical member and the mounting hole could occur due to the elasticity of the covering rubber interposed between the flange portion and the mounting hole.

[0008] The problem to be solved by the present invention is to provide a cylindrical vibration damping device with a novel structure that can accurately position the outer cylindrical member and the mounting hole in the axial direction while stably exerting a press-fitting fixing force on the outer cylindrical member made of synthetic resin into the mounting hole. [Means for solving the problem]

[0009] The following describes preferred embodiments for understanding the present invention. However, each embodiment described below is illustrative and can be combined with others as appropriate. Furthermore, the multiple components described in each embodiment can be recognized and adopted as independently as possible, and can be combined with any component described in another embodiment as appropriate. Thus, the present invention is not limited to the embodiments described below, and various other embodiments can be realized.

[0010] The first embodiment is a cylindrical vibration damping device having a structure in which an inner shaft member and an outer cylindrical member made of synthetic resin are connected by a main rubber elastic body, wherein the outer cylindrical member has a structure in which a cylindrical portion extends axially from the inner circumferential end of an annular flange portion, press-fit rubber is fixed to the outer circumferential surface of the cylindrical portion, and the axial surface of the flange portion on the side from which the cylindrical portion extends is exposed without being covered by the press-fit rubber, and a radially penetrating notch is provided at the axial end of the outer cylindrical member including the flange portion, and a connecting rubber connecting the main rubber elastic body and the press-fit rubber is provided in the notch.

[0011] In the cylindrical vibration isolator with a structure according to this embodiment, press-fit rubber is fixed to the outer circumferential surface of the cylindrical portion of the outer cylindrical member made of synthetic resin. When the outer cylindrical member is inserted into the mounting hole, the press-fit rubber is compressed radially between the outer cylindrical member and the circumferential wall of the mounting hole, and the outer cylindrical member is fixed in the mounting hole by the elasticity of the press-fit rubber. By adopting such a rubber press-fit structure, the plastic deformation (sagging) of the outer cylindrical member made of synthetic resin over time is less likely to affect the fixing force of the cylindrical vibration isolator to the mounting hole, and a stable mounting state of the cylindrical vibration isolator to the mounting hole is maintained.

[0012] The flange portion of the outer cylindrical member that overlaps the opening end face of the mounting hole is not fitted with press-fit rubber, and the exposed flange portion directly overlaps the opening end face of the mounting hole. Therefore, the rubber is not compressed between the overlapping surfaces of the flange portion and the opening end face of the mounting hole, preventing displacement of the outer cylindrical member toward the mounting hole due to the elasticity of the rubber.

[0013] In this embodiment, the main rubber elastic body and the press-fit rubber are connected by a connecting rubber provided in a notch formed at the axial end of the outer cylindrical member, including the flange portion. This makes it possible to integrally form the main rubber elastic body and the press-fit rubber without covering the overlapping surface with the opening end face of the mounting hole in the flange portion with rubber. Furthermore, since the notch is provided at the rear end in the direction of press-fitting the cylindrical vibration isolator into the mounting hole, it is possible to prevent the notch or connecting rubber from catching on the inner surface of the mounting hole, thereby preventing increased resistance during the initial press-fitting of the cylindrical vibration isolator into the mounting hole.

[0014] The second embodiment is a cylindrical vibration damping device as described in the first embodiment, wherein the connecting rubber is provided within the notch without protruding axially outward from the flange portion.

[0015] For example, if the connecting rubber protrudes beyond the flange portion toward the overlapping end face of the mounting hole, the elasticity of the connecting rubber pressed against the opening end face of the mounting hole may cause the outer cylindrical member to shift axially relative to the mounting hole. Also, if the connecting rubber protrudes beyond the flange portion toward the opposite side of the overlapping end face of the mounting hole, for example, when the flange portion is pushed axially to press-fit the outer cylindrical member into the mounting hole, the connecting rubber protruding axially outward from the flange portion may make it difficult to apply press-fitting force to the flange portion. The cylindrical vibration isolation device with a structure according to this embodiment solves the above problems, and the connecting rubber is less likely to interfere with the axial positioning of the outer cylindrical member and the mounting hole, as well as the input to the flange portion during press-fitting.

[0016] A third embodiment is a cylindrical vibration damping device as described in the first or second embodiment, wherein the main body rubber elastic body has a pair of cut holes formed on both radial sides of the inner shaft member, and the main body rubber elastic body is provided with a pair of rubber arms that extend radially between the pair of cut holes in the circumferential direction and connect the inner shaft member and the outer cylindrical member to each other, and the connecting rubber is arranged on the outer circumference of each rubber arm.

[0017] According to the cylindrical vibration damping device with a structure conforming to this embodiment, the connecting rubber is provided on the outer circumference of the pair of rubber arms, which makes it easier to integrally form the rubber arms, connecting rubber, and press-fit rubber during the vulcanization molding of the main rubber elastic body.

[0018] The fourth embodiment is a cylindrical vibration damping device described in any one of the first to third embodiments, wherein the connecting rubber has an outer peripheral projection that protrudes further outward than the press-fit rubber, provided between the circumferential ends of the flange portion in the notch, and the injection gate marks of the rubber material during molding of the connecting rubber are formed on the outer peripheral projection.

[0019] According to the cylindrical vibration isolator structured according to this aspect, by directly injecting a rubber material into the cavity of the outer peripheral protrusion that is at least partially located on the outer periphery of the press-fitted rubber during the vulcanization molding of the rubber, the press-fitted rubber fixed to the outer peripheral surface of the cylindrical portion can be molded with good filling properties of the rubber material.

[0020] A fifth aspect is the cylindrical vibration isolator described in any one of the first to fourth aspects, wherein an axial end portion on the opposite side of the flange portion in the cylindrical portion is a cylindrical press-fitting tip portion that is continuous over the entire circumference, and an outer peripheral surface of the press-fitting tip portion is exposed without being covered by the press-fitted rubber.

[0021] According to the cylindrical vibration isolator structured according to this aspect, since the press-fitting tip portion on the press-fitting tip side during press-fitting into the mounting hole is a continuous cylindrical shape over the entire circumference without having a notch or the like, for example, by the press-fitting tip portion contacting the inner peripheral surface of the mounting hole over the entire circumference, the outer cylinder member and the mounting hole are positioned, and it becomes easier to press-fit the outer cylinder member into the mounting hole in an appropriate direction. Further, since the outer peripheral surface of the press-fitting tip portion is exposed without being covered by the press-fitted rubber, the frictional resistance at the initial stage of press-fitting is reduced.

Effect of the Invention

[0022] According to the present invention, while stably exerting the press-fitting fixing force of the outer cylinder member made of synthetic resin into the mounting hole, the outer cylinder member and the mounting hole can be accurately positioned in the axial direction.

Brief Description of the Drawings

[0023] [Figure 1] Front view showing the cylindrical vibration isolator as the first embodiment of the present invention [Figure 2] Bottom view of the cylindrical vibration isolator shown in FIG. 1 [Figure 3] Right side view of the cylindrical vibration isolator shown in FIG. 1 [Figure 4] Cross-sectional view taken along line IV-IV of FIG. 1 [Figure 5] Cross-sectional view taken along line V-V of FIG. 1 [Figure 6]Figure 2, section VI-VI [Figure 7] Front view of the outer cylindrical member constituting the cylindrical vibration isolation device shown in Figure 1. [Figure 8] Right side view of the outer cylindrical member shown in Figure 7. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will be described below with reference to the drawings.

[0025] Figures 1 to 6 show a cylindrical vibration isolation device 10 as a first embodiment of the present invention. The cylindrical vibration isolation device 10 has a structure in which an inner shaft 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 vertical direction refers to the vertical direction in Figure 1, the left-right direction refers to the left-right direction in Figure 1, and the front-back direction refers to the vertical direction in Figure 2.

[0026] The inner shaft member 12 has a thick, small-diameter, substantially cylindrical shape and is equipped with a central hole 18 with a circular cross-section that penetrates axially. The inner shaft member 12 is formed from, for example, metal or synthetic resin and is a rigid member.

[0027] As shown in Figures 7 and 8, the outer cylindrical member 14 has a generally thin-walled, large-diameter, substantially cylindrical shape. The outer cylindrical member 14 integrally comprises a cylindrical tubular portion 20 and an annular plate-shaped flange portion 22 that protrudes outward from one axial end (front end) of the cylindrical portion 20. In other words, the outer cylindrical member 14 has a structure in which the cylindrical tubular portion 20 extends axially in the other direction (rear) from the inner circumferential end of the annular plate-shaped flange portion 22. The outer cylindrical member 14 is a rigid member formed from synthetic resins such as polyamide (PA), polypropylene (PP), and polytetrafluoroethylene (PTFE).

[0028] A pair of notches 24, 24 are formed at one axial end (front end) of the outer cylindrical member 14, which is provided with the flange portion 22. The notches 24 are formed to penetrate radially through the front end portion of the cylindrical portion 20 and the flange portion 22. Therefore, the notches 24 have a rectangular groove shape that extends radially at the front end portion of the cylindrical portion 20, and the flange portion 22 is divided circumferentially by the notches 24. In this embodiment, the pair of notches 24, 24 are arranged facing each other radially, and the flange portion 22 is divided into two circumferentially by the pair of notches 24, 24.

[0029] The inner shaft member 12 is positioned inside the outer cylindrical member 14, and the main rubber elastic body 16 is formed between the inner shaft member 12 and the outer cylindrical member 14. The main rubber elastic body 16 is generally cylindrical in shape, with its inner circumferential surface vulcanized and bonded to the outer circumferential surface of the inner shaft member 12, and its outer circumferential surface vulcanized and bonded to the inner circumferential surface of the cylindrical portion 20 of the outer cylindrical member 14.

[0030] The main rubber elastic body 16 has annular grooves 26 extending in the circumferential direction, which open to both axial ends. The main rubber elastic body 16 also has a pair of through-holes 28, 28 formed in the axial direction. The through-holes 28 are formed on both sides in the vertical direction relative to the inner shaft member 12, and extend in the left-right direction, with both ends reaching beyond the inner shaft member 12 in the left-right direction.

[0031] Between the upper and lower parts of the pair of grooves 28, 28 in the main rubber elastic body 16, a pair of rubber arms 30, 30 are formed, extending in the left-right direction and connecting the inner shaft member 12 and the outer cylindrical member 14 in the left-right direction. The pair of rubber arms 30, 30 are provided to connect an inner circumferential cylindrical portion 34 fixed to the outer circumferential surface of the inner shaft member 12 and an outer circumferential cylindrical portion 36 fixed to the inner circumferential surface of the outer cylindrical member 14 to each other in the left-right direction. The axial end face of the rubber arm 30 is formed of the bottom surface of the groove 26, and the inner circumferential cylindrical portion 34 and the outer circumferential cylindrical portion 36 protrude axially beyond the axial end face of the rubber arm 30.

[0032] A pair of stopper rubbers 32, 32 are formed above and below the pair of cut holes 28, 28 in the main rubber elastic body 16, projecting inward and upward from the outer cylindrical member 14 toward the inner shaft member 12. The relative vertical displacement between the inner shaft member 12 and the outer cylindrical member 14 is limited by the contact between the stopper rubbers 32 and the inner shaft member 12.

[0033] A press-fit rubber 38 is fixed to the outer circumferential surface of the cylindrical portion 20 of the outer cylindrical member 14. As shown in Figures 2 to 6, the press-fit rubber 38 integrally comprises a plurality of circumferential rubbers 40 extending in an annular shape in the circumferential direction, and a plurality of axial rubbers 42 extending axially between these plurality of circumferential rubbers 40.

[0034] The circumferential rubber 40 is an annular shape with a substantially constant cross-section that extends continuously around the entire circumference. In this embodiment, the rear end portion of the circumferential rubber 40, which is the press-fitting tip side, is a tapered portion 44 that becomes smaller in diameter towards the rear, and the front end portion, which is the press-fitting rear end side, extends axially with a substantially constant outer diameter. In this embodiment, three circumferential rubbers 40a, 40b, and 40c are provided spaced apart from each other in the axial direction.

[0035] The circumferential rubber 40a located at the front is spaced axially rearward from the flange portion 22 of the outer cylindrical member 14. The rear surface of the flange portion 22 is a contact surface 46 that is exposed to the outside without being covered by the press-fit rubber 38. Similarly, the front surface of the flange portion 22 is a pressing surface 48 that is exposed to the outside without being covered by rubber, just like the contact surface 46.

[0036] The circumferential rubber 40c located at the rear is spaced forward from the rear end of the cylindrical portion 20, and the portion of the cylindrical portion 20 rearward from the circumferential rubber 40c is exposed and not covered by the press-fit rubber 38. This exposed rear end portion of the cylindrical portion 20, not covered by the press-fit rubber 38, forms a continuous cylindrical press-fit tip portion 50 that extends around the entire circumference. Therefore, the cylindrical portion 20 has a flange portion 22 at one axial end (front end) and the other axial end (rear end) is the press-fit tip portion 50. In this embodiment, the outer circumferential surface of the press-fit tip portion 50 has a substantially constant diameter along its entire axial length, but for example, it may have a tapered surface that becomes smaller in diameter towards the rear end which becomes the press-fit tip, thereby providing a guide function when press-fitting into the mounting hole 62, which will be described later.

[0037] The axial rubber 42 extends linearly in the axial direction, and multiple axial rubbers are provided spaced apart from each other in the circumferential direction. Multiple axial rubbers 42 are provided in the axial space between the circumferential rubbers 40a and 40b, and in the axial space between the circumferential rubbers 40b and 40c. The axial rubbers 42 provided between the circumferential rubbers 40a and 40b have both axial ends integrally connected to the circumferential rubbers 40a and 40b, and connect them to each other. Similarly, the axial rubbers 42 provided between the circumferential rubbers 40b and 40c have both axial ends integrally connected to the circumferential rubbers 40b and 40c, and connect them to each other. The protrusion dimension of the axial rubbers 42 from the cylindrical portion 20 is smaller than the maximum protrusion dimension of the circumferential rubbers 40 from the cylindrical portion 20.

[0038] The axial rubber 42 is shaped so that both sides in the circumferential direction do not become undercuts when the molding die is removed in the left-right direction. The axial rubber 42 located in the center in the vertical direction has a larger circumferential width dimension than the other axial rubber 42, preferably more than twice that of the other axial rubber 42.

[0039] In the portion surrounded by the circumferential rubber 40 and the axial rubber 42, the outer surface of the cylindrical portion 20 may be exposed, or the outer surface of the cylindrical portion 20 may be covered with a thin rubber layer.

[0040] The pair of rubber arms 30, 30 are positioned circumferentially with respect to a pair of notches 24, 24 in the outer cylindrical member 14, with the pair of notches 24, 24 located on the outer circumference side of the pair of rubber arms 30, 30. It is desirable that the circumferential width dimension of the notches 24 be less than or equal to the circumferential width dimension of the outer circumference end of the rubber arms 30. It is desirable that the circumferential center of the notches 24 and the circumferential center of the rubber arms 30 coincide with each other, and in this embodiment, they are located in the center in the vertical direction. It is desirable that the notches 24 and the rubber arms 30 are separated from each other in the axial direction in the projection perpendicular to the axis (left-right direction), and it is desirable that the bottom surface of the notches 24 is located in front of the front end surface of the rubber arms 30 (bottom surface of the groove 26).

[0041] A connecting rubber 52 is fixed to the notch 24, connecting the main rubber elastic body 16 and the press-fit rubber 38. As shown in Figure 4, the connecting rubber 52 extends radially within the notch 24, with its inner circumference integrally connected to the outer cylindrical portion 36 of the main rubber elastic body 16, and its outer circumference integrally connected to the press-fit rubber 38. In short, in this embodiment, the main rubber elastic body 16, the press-fit rubber 38, and the connecting rubber 52 are integrally formed. As can be seen from the fact that a notch 24 is formed on the outer circumference of each of the pair of rubber arms 30, 30, the connecting rubber 52 in this embodiment is provided on the outer circumference of each of the pair of rubber arms 30, 30, and these pairs of connecting rubbers 52, 52 are substantially the same shape (symmetrical shape).

[0042] The connecting rubber 52 is provided with an outer peripheral projection 54 that protrudes outward. The outer peripheral projection 54 is provided in the divided portion of the flange portion 22 by the notch 24, and both ends in the circumferential direction are fixed to the circumferential end faces of the flange portion 22. The outer peripheral projection 54 protrudes further outward than the outer peripheral end of the press-fit rubber 38 (circumferential rubber 40). The outer peripheral projection 54 of the connecting rubber 52 has a thickness dimension in the front-rear direction that is smaller than the thickness dimension of the flange portion 22, and is provided within the thickness range of the flange portion 22 without protruding to either side in the front-rear direction relative to the flange portion 22, so that the connecting rubber 52 is provided within the notch 24 without protruding outward in the front-rear direction from the flange portion 22.

[0043] As shown in Figures 3 and 4, the connecting rubber 52 is connected to the circumferential rubber 40a by a connecting rubber 56 that extends axially from the notch 24 and is fixed to the outer circumferential surface of the cylindrical portion 20 of the outer cylindrical member 14. The connecting rubber 56, which constitutes the press-fit rubber 38, extends linearly in the axial direction with a circumferential width dimension that is approximately the same as that of the notch 24. It is desirable that the protrusion dimension of the connecting rubber 56 from the cylindrical portion 20 is less than or equal to the protrusion dimension of the circumferential rubber 40 from the cylindrical portion 20, and in this embodiment, it is approximately the same as the protrusion dimension of the axial rubber 42 from the cylindrical portion 20. The outer circumferential protrusion 54 of the connecting rubber 52 protrudes further outward than the connecting rubber 56. In this embodiment, the connecting rubber 52 includes a portion that covers the upper end surface of the notch 24 formation area in the cylindrical portion 20 and a portion (outer circumferential protrusion 54) fixed to the circumferential end surface of the notch 24 formation area in the flange portion 22. Furthermore, as described above, the outer peripheral projection 54 of this embodiment is provided in the flange portion 22 of the outer cylindrical member 14 at the portion divided by the notch 24, and in Figure 4, it includes not only the portion that protrudes above the outer peripheral surface of the connecting rubber 56, but also the portion located above the connecting rubber 56.

[0044] As shown in Figures 1 and 4, injection gate marks 58, which are traces of the rubber material injection gate, are provided protruding from the upper surface of the outer circumferential cylindrical portion 36 of the main rubber elastic body 16 and the connecting rubber 52. The injection gate marks 58 are composed of an inner circumferential injection gate mark 58a provided on the inner circumferential side and an outer circumferential injection gate mark 58b provided on the outer circumferential side, and are provided on the outer circumferential side (left and right outer sides) of a pair of rubber arms 30, 30, respectively. At least a portion of the inner circumferential injection gate mark 58a is located on the inner circumferential side of the cylindrical portion 20 of the outer cylindrical member 14, and preferably the entire portion is located on the inner circumferential side of the outer circumferential surface of the cylindrical portion 20. At least a portion of the outer circumferential injection gate mark 58b is located on the outer circumferential side of the cylindrical portion 20 of the outer cylindrical member 14, and preferably the entire portion is located on the outer circumferential side of the inner circumferential surface of the cylindrical portion 20. At least a portion of the outer circumferential injection gate mark 58b is provided protruding from the outer circumferential projection 54. It is desirable that, in the axial projection, at least a portion of the outer circumferential injection gate mark 58b overlaps with the connecting rubber 56. The inner circumferential injection gate mark 58a and the outer circumferential injection gate mark 58b are provided radially aligned at the same position relative to each other in the circumferential direction, and are spaced apart from each other in the radial direction (left-right direction).

[0045] Then, during the integral vulcanization molding of the main rubber elastic body 16, the press-fit rubber 38, and the connecting rubber 52, with the inner shaft member 12 and the outer cylindrical member 14 set in the molding die, rubber material is injected into the cavity of the molding die from the position of the injection gate mark 58. As a result, the rubber material injected from the inner injection gate that forms the inner injection gate mark 58a mainly forms the main rubber elastic body 16 and the connecting rubber 52 located on the inner circumference side of the cylindrical portion 20, and the rubber material injected from the outer injection gate that forms the outer injection gate mark 58b mainly forms the press-fit rubber 38 and the connecting rubber 52 located on the outer circumference side of the cylindrical portion 20. Thus, by setting an outer circumferential injection gate for injecting rubber material onto the outer circumferential side of the cylindrical portion 20, in addition to the inner circumferential injection gate for injecting rubber material onto the inner circumferential side of the cylindrical portion 20, it is possible to efficiently form a press-fit rubber 38 that is thinner than the main rubber elastic body 16, and the pressure difference between the inner and outer circumferential sides of the cylindrical portion 20 is reduced when the rubber material is injected, thereby suppressing deformation of the cylindrical portion 20.

[0046] As shown in Figure 4 or 5, the cylindrical vibration damping device 10, having the structure described above, is attached to a mounting target member 60, such as a vehicle body, by inserting the outer cylindrical member 14 into a mounting hole 62 provided in the mounting target member 60. The mounting hole 62 is larger in diameter than the outer diameter of the cylindrical portion 20 of the outer cylindrical member 14, and smaller in diameter than at least the maximum outer diameter of the circumferential rubber 40 of the press-fit rubber 38. When the cylindrical portion 20 of the outer cylindrical member 14 is inserted into the mounting hole 62, the press-fit rubber 38 is compressed radially between the cylindrical portion 20 of the outer cylindrical member 14 and the inner circumferential surface of the mounting hole 62, and the outer cylindrical member 14 is fixedly attached to the mounting hole 62 by the elasticity of the press-fit rubber 38. As described above, the outer cylindrical member 14 is attached to the mounting hole 62 by press-fitting with the press-fit rubber 38, and the fixing force to the mounting hole 62 is set by the spring characteristics and compression deformation amount (radial tightening allowance) of the press-fit rubber 38. The press-fit reaction force acting on the outer cylindrical member 14 is mitigated by the press-fit rubber 38, so even if the outer cylindrical member 14 is made of synthetic resin, plastic deformation (sagging) of the outer cylindrical member 14 due to the continuous action of the press-fit reaction force is suppressed, and a decrease in fixing force (pull-out resistance) due to sagging of the outer cylindrical member 14 is unlikely to be a problem.

[0047] The flange portion 22 of the outer cylindrical member 14 abuts against the open end face 64 of the mounting hole 62. This defines the axial position of the outer cylindrical member 14 relative to the mounting hole 62. The overlapping surface of the flange portion 22 with respect to the open end face 64 of the mounting hole 62 is an exposed contact surface 46 that is not covered by the press-fit rubber 38, and the flange portion 22 is overlapped in a state where it is in direct contact with the open end face 64 of the mounting hole 62. As a result, the rubber is not compressed between the overlapping surfaces of the contact surface 46 of the flange portion 22 and the open end face 64 of the mounting hole 62, preventing the outer cylindrical member 14 from coming out of the mounting hole 62 due to the elasticity of the rubber, and ensuring that the outer cylindrical member 14 is accurately positioned in the axial direction relative to the mounting hole 62.

[0048] The outer peripheral projection 54 of the connecting rubber 52, which is provided between the circumferential flange portions 22, does not protrude relative to the contact surface 46 of the flange portion 22, and is in contact with or separated from the open end surface 64 of the mounting hole 62 without being pressed against it. In this embodiment, as shown in an enlarged view in Figure 4, the outer peripheral projection 54 is in contact with the open end surface 64 of the mounting hole 62 without being strongly pressed against it.

[0049] By pressing the contact surface 46 of the flange portion 22 and the opposite pressing surface 48 with a jig, the outer cylindrical member 14 to which the press-fit rubber 38 is fixed can be press-fitted into the mounting hole 62. In this case, since the pressing surface 48 of the flange portion 22 is exposed and not covered by rubber, the force applied from the jig to the outer cylindrical member 14 is not reduced by the deformation of the rubber, allowing for efficient force application and press-fitting.

[0050] The end of the outer cylindrical member 14 on the press-fitting tip side is a press-fitting tip portion 50 that extends continuously around its entire circumference, and since there are no notches or the like, in the initial press-fitting stage when only the press-fitting tip portion 50 is inserted into the mounting hole 62, it is possible to prevent the outer cylindrical member 14 from tilting relative to the mounting target member 60, thereby positioning the outer cylindrical member 14 and the mounting target member 60 in the appropriate direction.

[0051] Furthermore, the press-fitting tip 50 of the outer cylindrical member 14 is exposed to the outside without being covered by rubber. Therefore, in the initial stages of press-fitting, the press-fitting tip 50, whose outer diameter is smaller than the inner diameter of the mounting hole 62, can be easily inserted into the mounting hole 62, and frictional resistance in the initial stages of press-fitting is suppressed.

[0052] In this embodiment, the press-fit rubber 38 has a structure that combines multiple circumferential rubbers 40 and multiple axial rubbers 42. This adjusts the spring constant when the press-fit rubber 38 is compressed radially between the cylindrical portion 20 of the outer cylindrical member 14 and the inner circumferential surface of the mounting hole 62. This ensures the necessary fixing force through rubber press-fitting while reducing the force required during press-fitting. In particular, since the maximum protruding height dimension of the circumferential rubber 40 is larger than the maximum protruding height dimension of the axial rubber 42, resistance to axial slippage from the mounting hole 62 of the outer cylindrical member 14 is efficiently exerted. Moreover, since the tip portion of the circumferential rubber 40 in the press-fitting direction is tapered 44 with a smaller diameter toward the press-fitting tip, resistance to slippage can be ensured while suppressing resistance during press-fitting.

[0053] Although embodiments of the present invention have been described in detail above, the present invention is not limited by its specific description. For example, the notch 24 may be provided only on the outer circumference of either one of the rubber arms 30. Furthermore, the notch 24 does not necessarily have to be positioned relative to the rubber arm 30 in the circumferential direction; for example, it may be provided on the outer circumference of the stopper rubber 32. In this case, the connecting rubber 52 provided in the notch 24 may be provided continuously on the outer circumference of the stopper rubber 32, for example.

[0054] In the main rubber elastic body 16, the pair of grooved holes 28, 28 and the pair of rubber arms 30, 30 extending between the grooved holes 28, 28 are not essential. For example, only one grooved hole 28 may be formed, or a main rubber elastic body without grooved holes 28 may be used that connects the inner shaft member 12 and the outer cylindrical member 14 to each other around the entire circumference.

[0055] The press-fit rubber 38 does not necessarily have to be a structure that combines circumferential rubber 40 and axial rubber 42 as shown in the above embodiment; for example, it may be cylindrical with a substantially constant cross-section extending around the entire circumference.

[0056] The injection gate mark 58 may consist of only one of the inner circumferential injection gate mark 58a and the outer circumferential injection gate mark 58b; for example, it may consist of only the inner circumferential injection gate mark 58a. Furthermore, the inner circumferential injection gate mark 58a and the outer circumferential injection gate mark 58b may be located at different positions in the circumferential direction; for example, one of them may be located on the outer circumferential side of the stopper rubber 32, 32. In addition, the injection gate mark 58 may include injection gate marks other than the inner circumferential injection gate mark 58a and the outer circumferential injection gate mark 58b, and the position and number of injection gates can be appropriately changed and set considering the filling properties of the rubber material according to the shape of the rubber to be molded. It is also possible to connect the inner circumferential injection gate mark 58a and the outer circumferential injection gate mark 58b in the above embodiment in the radial direction to form a single injection gate mark.

[0057] The present invention can also be applied to a fluid-filled cylindrical vibration isolation device equipped with a fluid chamber containing an incompressible fluid. [Explanation of symbols]

[0058] 10. Cylindrical Vibration Isolator (First Embodiment) 12 Inner shaft member 14 Outer cylindrical member 16 Main body rubber elastic body 18 Center hole 20 Cylindrical part 22 Flange section 24 Notches 26. Straight groove 28 slit holes 30 Rubber Arms 32 Stopper rubber 34 Inner cylindrical part 36 Outer cylindrical portion 38 Press-fit rubber 40 (40a~40c) Circumferential rubber 42 Axial rubber 44 Tapered section 46 Contact surface 48 Pressing surface 50 Press-fit tip 52 Connecting rubber 54 Outer protrusion 56 Connecting rubber 58 Injection gate marks 58a Inner circumferential injection gate marks 58b Outer perimeter injection gate marks 60 Mounting components 62 mounting holes 64 Open end face

Claims

1. A cylindrical vibration isolation device having a structure in which an inner shaft member and an outer cylindrical member made of synthetic resin are connected by a main body rubber elastic material, The outer cylindrical member has a structure in which a cylindrical portion extends axially from the inner circumferential end of the ring-shaped flange portion. The press-fit rubber is fixed to the outer circumferential surface of the cylindrical portion, and the axial surface of the flange portion on the side from which the cylindrical portion extends is exposed and not covered by the press-fit rubber. The axial end of the outer cylindrical member, including the flange portion, is provided with a radially penetrating notch. A cylindrical vibration damping device in which a connecting rubber is provided in the notch to connect the main body rubber elastic body and the press-fit rubber.

2. The cylindrical vibration damping device according to claim 1, wherein the connecting rubber is provided within the notch without protruding axially outward from the flange portion.

3. The main body rubber elastic material has a pair of grooves formed on both radial sides of the inner shaft member. The main body of the rubber elastic material is provided with a pair of rubber arms that extend radially between the pair of circumferential holes, connecting the inner shaft member and the outer cylindrical member to each other. The cylindrical vibration damping device according to claim 1 or 2, wherein the connecting rubber is arranged on the outer circumference of each rubber arm.

4. The connecting rubber has an outer peripheral projection that protrudes further outward than the press-fit rubber, provided between the circumferential ends of the flange portion in the notch. The cylindrical vibration damping device according to claim 1 or 2, wherein the injection gate marks of the rubber material during the molding of the connecting rubber are formed on the outer peripheral protrusion.

5. The cylindrical vibration damping device according to claim 1 or 2, wherein the axial end of the cylindrical portion opposite to the flange portion is a cylindrical press-fit tip that extends continuously around the entire circumference, and the outer surface of the press-fit tip is exposed without being covered by the press-fit rubber.

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