JP2000074116A - Cylindrical vibration isolating mount - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical vibration isolating mount with the load applied in the axial direction having such a structure that a shaft member and an outer cylinder member are resiliently coupled together by a cylindrical rubber piece interposed between them, in which the durability of the cylindrical rubber piece is enhanced. SOLUTION: An outside diameter changing part 31 is provided on the peripheral surface near the bottom of a shaft member 12 where a cylindrical rubber piece 15 is mounted so that the bottom part in the axial direction of the shaft member 12 is reduced in the diameter, and also a ring-shaped boring part 40 in a groove shape formed at the bottom surface in the axial direction of the rubber piece 15 is arranged so that the tensile force generated with elastic deformation of the rubber piece acts concentrically on the inside corner 42 of the boring part 40, and this inside corner 42 is positioned opposing to the outside diameter changing part 31 of the shaft member 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical anti-vibration mount that can be used for a cab mount, a subframe mount, a body mount, a member mount, and the like for an automobile, and in particular, when an initial load is applied in one axial direction. The present invention relates to a cylindrical anti-vibration mount to be mounted.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. 9-423 discloses a type of vibration-isolating connector interposed between members constituting a vibration transmission system.
As disclosed in Japanese Patent Publication No. 42-42, etc., it has a structure in which a shaft metal fitting and an outer cylindrical metal fitting arranged radially apart from each other are connected by a cylindrical rubber elastic body interposed between the two metal fittings. ,
2. Description of the Related Art A tubular anti-vibration mount is known in which a shaft fitting and an outer cylindrical fitting are attached to each member to be vibration-isolated and connected to the members to be vibration-isolated.
For example, those used for cab mounts, subframe mounts, body mounts, and the like for automobiles.

By the way, in such a cylindrical anti-vibration mount, the weight or the like of a supported body such as a cab or a body in an attached state is determined as an initial load in an axial direction with respect to a shaft fitting and an outer cylinder fitting. Often entered. When the initial load is input, the shaft fitting is relatively displaced to one side in the axial direction with respect to the outer cylinder fitting with the elastic deformation of the cylindrical rubber elastic body under the mounted state of the cylindrical vibration isolating mount. It will be positioned. When a particularly large initial load is input, the amount of tensile deformation generated in the cylindrical rubber elastic body tends to increase at the front end in the moving direction of the shaft bracket due to the initial load. Cracks tend to occur.

Therefore, conventionally, for example, as described in the above-mentioned publication, the cylindrical rubber elastic body is opened at the axial end face on the front side in the displacement direction of the shaft bracket due to the initial load and is formed in the circumferential direction. The stress generated is reduced by providing a grooved annular portion extending continuously to the cylindrical rubber elastic body and increasing the surface area of the axial end surface of the cylindrical rubber elastic body. Furthermore, in such an annular girder, generally, the inner circumference at the bottom surface of the annular girder has to be secured in order to secure a rubber volume of an inner peripheral portion having a short circumferential length and to make the generated stress in the cylindrical rubber elastic body uniform. The radius of curvature of the side corner portion is set to be larger than the radius of curvature of the outer peripheral side corner portion, or the deepest portion in the axial direction of the annular portion is located on the outer peripheral side of the radial center point of the cylindrical rubber elastic body. For example, the inner peripheral portion of the cylindrical rubber elastic body is formed to protrude outward in the axial direction from the outer peripheral portion.

[0005] However, even if such a conventional annular bead is employed, it is difficult to avoid the occurrence of cracks at the axial end face of the cylindrical rubber elastic body due to an initial load or vibration load input in the axial direction. Since the dynamic spring characteristics of the mount change due to the generation of cracks, there is a problem that it is difficult to secure sufficient durability and stable characteristics.

[0006]

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the occurrence of cracks from an axial end face of a cylindrical rubber elastic body. Another object of the present invention is to provide a cylindrical anti-vibration mount having a structure that can be prevented and the desired anti-vibration performance can be advantageously maintained.

[0007]

In order to solve such a problem, a feature of the present invention is that a shaft member and an outer cylinder member spaced apart on the outer peripheral side of the shaft member are moved in a direction perpendicular to their axes. Connected by the cylindrical rubber elastic body interposed between the opposing surfaces, and with respect to one end face in the axial direction of the cylindrical rubber elastic body,
In a cylindrical anti-vibration mount provided with a concave groove-shaped annular bulge extending continuously in the circumferential direction, the cylindrical rubber elastic body located near an axial end of the shaft member on the side of the annular bulge is provided. An outer diameter dimension changing portion is provided on the attached outer peripheral surface to reduce the diameter of an axial end of the shaft member on the side of the annular bulge portion, while the shaft member is positioned with respect to the outer cylindrical member. When displaced in the axial direction toward the annular bulge, the cylindrical rubber elastic body provided with the annular bulge is pulled toward the inner peripheral corner of the bottom surface of the annular bulge. The shape of the bottom surface of the annular girder is set so that stress acts intensively, and the inner peripheral corner of the annular girder is positioned to face the outer diameter dimension change portion of the shaft member. It is in.

[0008] In such a cylindrical anti-vibration mount having a structure according to the present invention, an axial load such as an initial load is input between the shaft member and the outer cylinder member, and the shaft member is moved relative to the outer cylinder member. When it is relatively displaced toward the annular bulge, the tensile effect of the cylindrical rubber elastic body is likely to act intensively. Be demonstrated. Then, the concentration of tensile stress at the inner peripheral corner of the cylindrical rubber elastic body is reduced or prevented, and the generation of cracks and the like in the cylindrical rubber elastic body is prevented, so that the target spring characteristic is improved. It is kept effective and has excellent mount durability.

Further, in such a cylindrical vibration-proof mount, the inner peripheral corner of the annular bulge portion of the cylindrical rubber elastic body is opposed to the outer diameter dimensional change portion of the shaft member. Even if a crack is generated in the inner peripheral corner, the growth of the crack is advantageously suppressed by the outer diameter dimension change portion of the shaft member, and the adverse effect on the mount spring characteristics is reduced or prevented. As a result, excellent durability is exhibited.

In the cylindrical anti-vibration mount according to the present invention, a configuration in which the outer diameter dimensional change portion of the shaft member is a tapered outer peripheral surface inclined in the axial direction is preferably adopted. If such an outer diameter dimensional change portion having such a tapered outer peripheral surface is employed, the outer diameter dimensional change portion is more advantageously provided on the inner peripheral side corner of the bottom surface of the annular hollow portion in the cylindrical rubber elastic body. Since the outer diameter is changed, the reinforcing effect and the crack growth suppressing effect by the outer diameter dimension changing portion can be more effectively exerted.

Further, in the cylindrical vibration isolating mount according to the present invention, for example, a configuration in which the inner diameter at the opening of the annular burring is smaller than the maximum outer diameter at the outer diameter dimensional change portion of the shaft member, It is preferably adopted. With such a configuration, the reinforcing effect of the outer diameter dimension changing portion of the shaft member is more effectively exerted on the inner peripheral corner of the cylindrical rubber elastic body.

Further, in the cylindrical anti-vibration mount according to the present invention, when the shaft member and the outer cylinder member are relatively displaced in the axial direction, the tensile stress is concentrated on the inner peripheral corner of the bottom surface of the annular burring. In setting the shape of the bottom surface of the annular bulging portion that acts, for example, (a) a configuration in which the radius of curvature of the inner peripheral corner at the bottom surface of the annular burring portion is smaller than the radius of curvature of the outer peripheral corner; b) At least one of a configuration in which the deepest point in the axial direction of the annular drilling portion is located on the inner peripheral side of the radial center of the annular drilling portion is suitably adopted.

In particular, in the case of adopting the above-mentioned configuration (a), the inner peripheral corner at the bottom surface of the annular burring section is formed into an arc-shaped cross section having a substantially constant radius of curvature, and the arc-shaped cross section is formed. It is preferable to adopt a configuration in which the center point in the circumferential direction is located on the outer peripheral surface on the axial end side where the outer diameter dimension changing portion or the annular burring portion of the shaft member opens.
More preferably, the center point in the circumferential direction of the arc-shaped cross section that forms the inner peripheral corner at the bottom surface of the annular beam is located on the outer diameter dimension changing portion of the shaft member in the axial projection. Configuration is adopted. By employing such a configuration, the reinforcing effect on the inner peripheral corner of the cylindrical rubber elastic body by the outer diameter dimension changing portion of the shaft member is more effectively exerted.

On the other hand, in the case of employing the configuration (b), the axially deepest point in the annular member is defined by the outer diameter dimension changing portion of the shaft member or the axial direction in which the annular member opens. It is desirable to adopt a configuration located on the outer peripheral surface on the end side. By employing such a configuration, the reinforcing effect on the inner peripheral corner of the cylindrical rubber elastic body by the outer diameter dimension changing portion of the shaft member is more effectively exerted.

In the cylindrical anti-vibration mount according to the present invention, for example, the outer peripheral surface shape of the shaft member and the inner peripheral surface shape of the outer cylindrical member are each cylindrical, and the outer diameter dimensional change portion is provided on the shaft. A configuration in which the annular member is formed with a substantially constant cross-sectional shape over the entire circumferential direction between the shaft member and the outer cylindrical member, while being continuously formed over the entire circumferential direction of the member. It is preferably adopted. If such a configuration is adopted, the tensile stress acting on the bottom surface of the annular drilling portion is made uniform in the circumferential direction, and the outer peripheral dimension of the cylindrical rubber elastic body is changed by the outer diameter dimension changing portion of the shaft member. The reinforcing effect is advantageously exerted over the entire circumference of the cylindrical rubber elastic body, whereby more excellent durability is exhibited.

Further, in the cylindrical anti-vibration mount according to the present invention, for example, a structure provided with a stopper mechanism for limiting an axial displacement amount of the shaft member with respect to the annular cylindrical portion with respect to the outer cylindrical member is preferably employed. Is done. If such a stopper mechanism is employed, excessive deformation of the cylindrical rubber elastic body due to input of an excessive vibration load or the like is prevented, so that the durability of the cylindrical rubber elastic body is further improved. . Such a stopper mechanism, for example, allows the shaft member to protrude outward in the axial direction from the cylindrical rubber elastic body or the outer cylindrical member at the axial end opposite to the small-diameter portion, and the projecting end of the shaft member. A stopper member that extends outward in the direction perpendicular to the axis is fixed to the portion, and the stopper member is axially opposed to the cylindrical rubber elastic body and the axial end surface of the outer cylindrical member. , Advantageously configured. In this case, it is desirable to provide a cushioning material such as a cushioning rubber between the opposing surfaces of the stopper member and the cylindrical rubber elastic body or the outer cylindrical member. Furthermore, a stopper mechanism for limiting the relative displacement between the shaft member and the outer cylinder member in a direction opposite to the initial load input direction,
Of course, it can be adopted.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

First, FIGS. 1 to 3 show a cab mount 10 for an automobile as a first embodiment of the present invention. The cab mount 10 has a substantially thick cylindrical shape in which an inner cylinder fitting 12 as a shaft member and an outer cylinder fitting 14 as an outer cylinder member are radially separated from each other and are interposed therebetween. It is structured to be elastically connected by a main rubber elastic body 15 as a rubber elastic body. As shown in FIG. 4, the cab mount 10 has the outer cylinder 14 fixed to the frame 16 by the fixing bolt 18, while the inner cylinder 12 is fixed to the body 20. By being fixed with the insertion bolts 22, the frame 16 and the body 20 of the full frame type automobile are
The body 20 is supported by the frame 16 in a vibration-proof manner. In such a mounted state, the weight of the body 20 as an initial load: P
(See FIG. 4) is input in the axial direction between the inner and outer cylindrical fittings 12, 14, and the inner cylindrical fitting 12 is located on one axial side (downward in FIGS. 1 and 4) with respect to the outer cylindrical fitting 14. The initial displacement is performed by a fixed amount, and the main vibration to be damped is input in a substantially axial direction between the inner and outer tube fittings 12 and 14. In the following description, the vertical direction refers to the vertical direction in FIG. 1 in principle.

More specifically, the inner cylindrical member 12 has a straight small-diameter cylindrical shape, and a flange-like flange portion 24 protruding on the outer peripheral surface is integrally formed at the upper end in the axial direction. . Further, a substantially annular plate-shaped stopper plate 26 is superposed on the outer surface of the flange portion 24 in the axial direction.
, The inner cylindrical fitting 12 is coaxially fixed on the upper end face in the axial direction of the inner cylindrical fitting 12 so as to spread radially outward.

At the axially intermediate portion of the inner cylindrical fitting 12, an intermediate tapered cylindrical portion 25 is formed at the lower end portion in the axial direction and gradually decreases in diameter with a substantially constant inclination angle as going downward in the axial direction. And the intermediate tapered tube portion 2
The upper part and the lower part in the axial direction, which are located on both sides in the axial direction with respect to 5, are a large-diameter cylindrical part 27 and a small-diameter cylindrical part 29. That is, in the present embodiment, the thickness of the inner cylindrical member 12 is substantially constant throughout, and the outer peripheral surface of the intermediate tapered cylindrical portion 25 forms the tapered outer diameter dimension changing portion 31. At the same time, the small-diameter cylindrical portion 29 forms a small-diameter portion. In the present embodiment, the large-diameter cylindrical portion 27 and the small-diameter cylindrical portion 2
Each of 9 has a straight pipe shape whose inner and outer diameters are substantially constant over the entire length in the axial direction.

As shown in FIG. 4, the upper end face of the inner cylinder fitting 12 on the stopper plate 26 side in the axial direction is closely overlapped with the lower face of the body 20 of the automobile, and the inner metal fitting 12 is axially arranged. Inserted rod-shaped insertion bolt 2
2 allows the body 20 to be attached by being fixed to the body 20. The insertion bolt 22
Has a stepped rod shape substantially corresponding to the inner peripheral surface shape of the inner cylinder fitting 12, and is fitted into each inner peripheral surface of the large-diameter cylindrical portion 27 and the small-diameter cylindrical portion 29 of the inner cylinder fitting 12. It has become.

When mounting the inner cylinder fitting 12 to the body 20, a rebound stopper plate 33 having an annular plate shape substantially the same as the stopper plate 26 is superimposed on the lower end face in the axial direction of the inner cylinder fitting 12, and the insertion bolt is provided. By 22, it is fixed in a state of spreading in a direction perpendicular to the axis. The upper surface of the rebound stopper plate 33 is provided with a shock-absorbing rubber 35 extending continuously from the outer peripheral portion in the circumferential direction.

On the other hand, the outer cylinder fitting 14 is
It has a substantially cylindrical shape with a larger diameter and a smaller axial length, and is arranged substantially coaxially with the inner cylinder fitting 12. Further, an intermediate tapered tube portion 28 that gradually expands toward the lower side in the axial direction is formed at an axially intermediate portion of the outer tube fitting 14, and an axially upper portion positioned with the intermediate tapered tube portion 28 interposed therebetween. The lower part is a small-diameter cylindrical part 30 and a large-diameter cylindrical part 32. In the present embodiment, the outer tube fitting 1 is used.
4, the thickness of the small-diameter cylindrical portion 3
The inner diameter of the large-diameter cylindrical portion 32 is larger than that of 0. In the present embodiment, the small-diameter cylindrical portion 30 and the large-diameter cylindrical portion 3
Each of the two has a straight pipe shape whose inner diameter is substantially constant over the entire length in the axial direction.

In particular, the outer tube fitting 14 of the present embodiment is folded at the end on the side of the small-diameter tube portion 30 and closely overlaps with the outer peripheral surface, so that the small-diameter tube portion 30 has a double-tube structure. ing. The end on the turn-back side is bent outward in the radial direction on the outer peripheral surface of the intermediate tapered tubular portion 28, and thereby is expanded into an annular flat plate shape having a plurality of bolt insertion holes 36. The plate part 34 is formed integrally with the outer tube fitting 14. In the present embodiment, the mounting plate portion 34 has a substantially rhombic planar shape that protrudes largely outward at a pair of radial portions opposed to each other, and each of the mounting plate portions 34 has one Bolt insertion hole 3
6 are formed.

Then, as shown in FIG. 4, the mounting plate portion 34 is superimposed on the frame 16 of the automobile, and the mounting plate portion 34 is fixed to the frame 16 by the fixing bolts 18 inserted into the bolt insertion holes 36. It is supposed to be. In addition, the above-described inner cylinder fitting 12, outer cylinder fitting 14, stopper plate 26, and the like are rigid members that do not substantially deform when a load is input, and are formed of, for example, a steel material or an aluminum alloy material.

The outer cylindrical member 14 is disposed substantially radially outward and substantially coaxially with the inner cylindrical member 12 at an axially intermediate portion of the inner cylindrical member 12 which is deviated downward in the axial direction. The middle tapered tube portion 28 of the outer tube fitting 14 is positioned axially above the intermediate tapered tube portion 25 of the inner tube member 12, and the large-diameter tube portion 32 of the outer tube member 14 is The tapered cylindrical portion 25 of the metal fitting 12, the large-diameter cylindrical portion 27, and the small-diameter cylindrical portion 29 are radially opposed to each other. The large diameter cylindrical portion 27 of the cylindrical metal fitting 12 is radially opposed to the large diameter cylindrical portion 27. Further, in such an arrangement state, the main rubber elastic body 15 is interposed between the radially opposed surfaces of the inner cylindrical fitting 12 and the outer cylindrical fitting 14, and the main rubber elastic body 1 is provided.
5, the inner and outer cylindrical fittings 12, 14 are elastically connected. The main rubber elastic body 15 has a thick, substantially cylindrical shape as a whole, and in the present embodiment, an integrally vulcanized molded product whose inner and outer peripheral surfaces are vulcanized and bonded to the inner and outer cylindrical fittings 12 and 14. It is formed as.

Further, a thick buffer rubber 37 is formed over substantially the entire lower surface of the stopper plate 26 fixed to the inner cylinder fitting 12. The cushion rubber 37 is integrally formed with the main rubber elastic body 15 by an inner peripheral portion extending in a cylindrical shape in the axial direction along the surface of the inner cylindrical metal fitting 12 and being connected to the main rubber elastic body 15. Are vulcanized and bonded to the inner tube fitting 12 and the stopper plate 26. Further, the outer diameter of the opening end of the outer cylinder fitting 14 on the small-diameter cylinder portion 30 side is smaller than the outer diameter of the stopper plate 26, and the opening end of the outer cylinder fitting 14 is formed of a stopper plate. The cushion rubber 37 on the upper surface 26 is spaced apart in the axial direction and opposed to the cushion rubber 37. And, this outer tube fitting 14
The upper end in the axial direction of the main body and the upper end in the axial direction of the rubber elastic body 15 are connected to the stopper plate 2 via the cushion rubber 37.
6, the outer cylinder 14 of the inner cylinder 12
, The relative displacement amount of P in the input direction (bound direction) of P is limited.

Note that the lower end surface of the outer tube fitting 14 in the axial direction is
A cushion rubber 39 protruding outward in the axial direction is provided continuously in the circumferential direction. This cushion rubber 39 is formed integrally with the main rubber elastic body 15 and is vulcanized and bonded to the outer tube fitting 14. The buffer rubber 39 protruding from the lower end surface of the outer tube fitting 14 as described above is axially attached to the rebound stopper plate 33 fixed to the lower end portion in the axial direction of the inner tube fitting 12 in the mounted state. It is designed to be spaced apart in the direction and to be opposed to each other. Accordingly, when an excessive axial reaction load (rebound load) is input between the inner and outer cylinder fittings 12 and 14, the rebound stopper plate 33 causes the rebound stopper plate 33 to move through the cushion rubbers 35 and 39.
By contacting the lower end surface of the outer cylinder 14, the relative displacement of the inner cylinder 12 in the rebound direction with respect to the outer cylinder 14 is limited.

Here, in the present embodiment, the main rubber elastic body 15 extends over substantially the entire area between the radially opposed surfaces of the inner cylindrical fitting 12 and the outer cylindrical fitting 14, that is, over substantially the entire axial length. It is interposed. In addition, the main body rubber elastic body 15
The upper end face 38 in the axial direction is positioned so that the inner peripheral edge portion protrudes outward in the axial direction from the outer peripheral edge portion, and is in a state before mounting as shown in FIG. 1 (when an initial load is input). In a state (not in the state), it is formed in a substantially tapered shape or a mountain shape that gradually protrudes upward in the axial direction from the outer cylinder fitting 14 side to the inner cylinder fitting 12 side. On the other hand, the lower end surface in the axial direction of the main rubber elastic body 15 is provided with a groove 40 as a concave groove-shaped circular groove which is open downward in the axial direction and continuously extends in the circumferential direction with a substantially constant cross-sectional shape. ing.

As shown in an enlarged sectional view of FIG. 5, such a groove 40 has a substantially U-shaped cross section as a whole, and its inner peripheral corner 42 and outer peripheral corner 44 are
Each of them has a substantially circular cross-sectional shape having a substantially constant radius of curvature. In addition, the radius of curvature R1 of the inner peripheral corner 42 is set smaller than the radius of curvature R2 of the outer peripheral corner 44. Further, in the cross section of the groove 40, the outer peripheral wall surface 46 is formed.
Is substantially entirely formed by the outer peripheral corner 44 of the radius of curvature R2 centered on the center point O2, while the inner peripheral wall surface 48 of the kerf groove 40 is centered on the center point O1. Radius of curvature: formed by a linear surface extending tangentially from the inner peripheral corner 42 of R1. In addition,
The inner peripheral wall surface 48 is a cylindrical surface that extends substantially parallel to the mount center axis 50, and its radial dimension (the inner diameter of the groove 40): r 1 is the diameter of the large-diameter cylinder of the inner cylinder fitting 12. The outer diameter of the portion 27 (the maximum outer diameter of the outer diameter changing portion 31) is set to be smaller than r2. In the cross-sectional shape, the bottom surface 52 of the groove 40 has an arc of a radius of curvature: R1 and an outer corner 4 that constitute the inner corner 42.
4 are connected smoothly by the radius of curvature: R2, in other words, by being connected at a continuous point: C having a common tangent, these inner peripheral corners 4 are connected.
2 are formed in cooperation with an arc having a radius of curvature: R1 and an arc having a radius of curvature: R2 forming the outer peripheral corner 44.

In the cross-sectional shape of the groove 40, the center angle θ1 of the inner peripheral corner 42, which has a substantially arc shape with a radius of curvature of R1, is substantially an arc shape with a radius of curvature of R2. The central angle of the outer peripheral side corner portion 44 is larger than θ2,
Specifically, it is set so that θ1> 90 degrees> θ2. Further, the bottom surface 52 connecting the inner peripheral corner 42 and the outer peripheral corner 44 is an inclined surface which is inclined radially inward from the outer peripheral side toward the inner peripheral side as a whole. Thereby, the deepest portion 54 of the groove 40 is positioned on the arc of the inner peripheral corner 42, and the deepest portion 54 is positioned at the radial center of the groove 40 and the thickness center of the main rubber elastic body 15. Are located on the inner circumference side.

In this embodiment, the groove 4
In the cross-sectional shape of 0, the bisector 56 of the central angle: θ1 at the inner peripheral corner 42 having a substantially circular arc shape with a radius of curvature: R1 is shifted from the arc center point: Q of the inner peripheral corner 42 to the main body. It extends obliquely inward in the radial direction toward the inside of the rubber elastic body 15 and intersects the mount center axis 50 at an intersection angle: θ0.

Further, as shown in FIG. 5, the inner circumferential corner 42 of the groove 40 having an arc-shaped cross section is
The outer diameter dimension changing portion 31 of the inner tube fitting 12 (the intermediate tapered tube portion 2)
5). That is, the inner peripheral corner 42 of the groove 40 is, in many parts thereof,
The outer diameter dimension changing section 31 of the inner cylinder fitting 12 is positioned outside the outer diameter dimension changing section 31, that is, in a direction substantially perpendicular to the outer diameter dimension changing section 31. The inner surface of the inner peripheral corner 42 of the straightening groove 40 as a whole constitutes the rubber elastic body 1 forming the bottom wall of the straightening groove 40.
5, it is positioned so as to face the outer diameter dimension changing portion 31 of the inner cylinder fitting 12.

Further, in the present embodiment, the arc center point Q of the inner peripheral corner 42 overlaps the outer diameter dimension changing portion 31 of the inner cylinder fitting 12 in the axial and radial projections. It is located in. In particular, in the present embodiment,
On the axial and radial coordinates, the inner peripheral corner 4
The center point Q of the circular arc of No. 2 is located at substantially the center of each of the axial length: L and the radial width: B of the outer diameter dimension changing portion 31 of the inner cylinder fitting 12. The outer diameter dimensional change portion 31 is opposed to a substantially central portion thereof. Furthermore, in the present embodiment, the entire substantially arc-shaped portion having the radius of curvature: R1 that forms the inner peripheral corner 42 is entirely covered with the inner cylinder fitting 12.
The outer diameter dimension changing portion 31 overlaps with the outer diameter dimension changing portion 31 in the radial direction, and even in the axial direction, the whole or almost all of the portion overlaps the outer diameter dimension changing portion 31 of the inner cylinder fitting 12. It is located in.

Cab mount 1 structured as described above
In FIG. 4, the initial load P due to the weight of the body 20 is applied between the inner and outer cylindrical fittings 12 and 14 in the axial direction as shown in FIG. 4, and the main rubber elastic body 15 is elastically deformed. As a result, the inner cylindrical fitting 12 is mounted between the frame 16 and the body 20 of the automobile in a state where the inner cylindrical fitting 12 is displaced axially downward with respect to the outer cylindrical fitting 14.

Under such an attached state, the axial lower end surface of the main rubber elastic body 15 tends to have a large shear strain due to the elastic deformation of the main rubber elastic body 15 due to the initial load: P. Since the surface area is enlarged by 40, the generated stress is reduced and the durability is improved. Moreover, there, the inner peripheral corner 42 of the inner surface of the groove 40 is deformed in a direction in which the radius of curvature is increased and opened when an initial load: P or an axial vibration load is input. Aggressive stress concentration is likely to occur near the arc center point Q of the inner peripheral corner 42, but the inner peripheral corner 42 is located outside the outer diameter dimension changing portion 31 of the inner cylinder fitting 12. The main rubber elastic body 15 constituting the inner peripheral corner 42 is reinforced by the outer diameter dimensional change portion 31, thereby suppressing the amount of elastic deformation of the inner peripheral corner 42. Can be Thereby, the stress concentrated on the inner peripheral side corner portion 42 is dispersed, and
The locally concentrated stress is dispersed in the groove 40, and the maximum stress is reduced by reducing or avoiding the concentration of the stress. As a result, the main rubber elastic body 15 and the cab mount 10 are reduced. Thus, the improvement of the durability is realized.

In addition, in the present embodiment, in the axial lower end surface of the main rubber elastic body 15, in the cross-sectional shape, a wide portion on the outer peripheral side (in FIG. 5, an arc-shaped portion having a radius of curvature: R 2) is formed. The initial load: P is inclined downward in the axial direction from the inner peripheral side to the outer peripheral side.
Is input, elastic deformation occurs such that the surface area of the lower end surface in the axial direction decreases on the lower end portion in the axial direction of the main rubber elastic body 15. Thereby, the main body rubber elastic body 15
The tensile stress itself that occurs is also reduced, especially,
Since the generation of tensile stress at the outer peripheral corner 44 of the groove 40 is suppressed, the durability of the main rubber elastic body 15 is further improved in combination with the effect of reducing the tensile stress at the inner peripheral corner 42 as described above. Is ensured.

Moreover, since the inner peripheral corner 42 where stress concentration is likely to occur in the groove 40 is located opposite to the outer diameter dimensional change portion 31 of the inner cylindrical fitting 12, it is temporarily assumed that the inner peripheral corner 42 is located at the inner peripheral side. Even if a crack due to stress concentration occurs in the corner 42, the growth of such a crack can be effectively damped. That is, the crack in the inner peripheral corner 42 of the groove 40 is generated in a direction substantially perpendicular to the tensile stress in the rubber elastic body 15, in other words, in a direction substantially perpendicular to the surface of the groove 40. The outer diameter dimension changing portion 31 of the inner cylindrical metal fitting 12 opposed to the inner peripheral corner 42;
The growth of the main rubber elastic body 15 can be suppressed by the existence of the crack, so that the influence of the crack on the main rubber elastic body 15 can be suppressed, and the original effective spring characteristics of the main rubber elastic body 15 can be well maintained.

Further, the cab mount 10 of this embodiment
, The upper end surface 38 of the main rubber elastic body 15 in the axial direction
Has a tapered surface that protrudes outward in the axial direction toward the inner peripheral side, so that when the initial load: P is input, the axially upper end of the main rubber elastic body 15 also An elastic deformation occurs such that the surface area of the upper end surface 38 in the direction decreases. As a result, compressive deformation is advantageously generated in the main rubber elastic body 15, and tensile deformation is reduced or prevented, and further pre-compression or the like after vulcanization molding is not required, and further. An improvement in durability can be realized.

Next, FIGS. 6, 7 and 8 show cab mounts 60, 62 and 64 as second, third and fourth embodiments of the present invention, respectively. Note that the cab mounts 6 of the second, third and fourth embodiments
Reference numerals 0, 62, and 64 denote different structural examples of the outer tube fitting 14 compared to the cab mount 10 of the first embodiment, and have the same structure as that of the first embodiment. The same reference numerals as in the first embodiment denote the same members and parts in the drawings, and a detailed description thereof will be omitted.

That is, the shape of the outer cylinder member employed in the present invention is, as described in the first embodiment, a double cylinder wall structure by folding, a stepped cylindrical shape having an intermediate tapered cylinder portion 28, or the like. It is not limited, and various cylindrical structures can be adopted according to required characteristics and the like.In addition, regardless of the specific structure and shape of such an outer cylindrical member, The reinforcing effect and the like on the inner peripheral corner 42 of the groove 40 by the outer diameter dimension changing portion 31 of the metal fitting 12 can be effectively exhibited.

More specifically, in the cab mount 60 shown in FIG.
Without being folded back in the axial direction at the open end of the
It is bent at a substantially right angle radially outward. Thus, the small-diameter cylindrical portion 30 of the outer cylindrical fitting 14 has a single cylindrical wall structure, and the mounting plate portion 34 extends in a radially outward direction from the peripheral edge of the opening on the small-diameter cylindrical portion 30 side. Is formed.

The cab mount 62 shown in FIG.
In the above, the outer tube fitting 14 is formed in a straight tube shape having a constant inner and outer diameter over the entire length in the axial direction without providing an intermediate tapered tube portion at an intermediate portion in the axial direction. Moreover,
At the opening at the upper end in the axial direction of the outer tube fitting 14, the outer metal fitting 14 is bent substantially at right angles to the outside in the radial direction without being folded back to the opposite side in the axial direction. A mounting plate portion 34 extending in the direction is integrally formed.

Further, the cab mount 6 shown in FIG.
In FIG. 4, as shown in FIGS. 9 and 10, similarly to the first embodiment, the outer tube fitting 14 is folded at the upper end in the axial direction, so that the upper portion has a double tube structure. However, in the double cylindrical portion 66, an opposing cylinder that is opposed in one radial direction (the left-right direction in FIG. 9) corresponding to the opposing direction of the pair of bolt insertion holes 36, 36 in the mounting plate 34. The wall portions 68, 68 are reduced in diameter so as to be crushed inward in the radial direction, and have a substantially flat plate shape extending parallel to each other and linearly in the circumferential direction with a two-surface width.
In short, the double tubular portion 66 of the outer tubular fitting 14 has a pair of flat tubular opposed tubular walls 68, 68 extending linearly in the circumferential direction, and is orthogonal to the facing direction of the opposed tubular walls 68, 68. The cylindrical wall portions 70, 70 facing each other in the radial direction
It has a pair of circular arc plates extending in a circular shape in the circumferential direction, and has a generally oval cylindrical shape or a substantially elliptical cylindrical shape as a whole.

The lower part of the outer tube fitting 14 not having the double tube structure has a cylindrical shape having substantially the same inner and outer diameters as the arc-shaped tube wall 70. in short,
The outer tube fitting 14 has an intermediate tapered tube portion 28 formed only in a portion of the mounting plate portion 34 that faces one direction in the radial direction corresponding to the direction in which the pair of bolt insertion holes 36 and 36 face each other. The portion in which the intermediate tapered tube portion 28 is not formed is formed in a straight tube wall shape having a constant inner diameter over the entire length in the axial direction. is there.

As described above, in the double cylindrical portion 66 extending upward in the axial direction from the mounting plate portion 34, the flat cylindrical opposing cylindrical wall portions 68, 68 are formed, and the bolt insertion holes 36 in the mounting plate portion 34 are formed. , 36 only in the direction in which the outer cylindrical fitting 14 is reduced, so that the volume of the main rubber elastic body 15 is advantageously secured while the bolt insertion hole 3 of the mounting plate portion 34 is secured.
It is possible to improve the workability of attaching bolts to the 6, 36.

Further, in this embodiment, in particular, in the outer cylinder 1
4, between the flat opposed wall portions 68, 68 and the radially opposed surfaces of the inner cylindrical fitting 12, each of which is opened at the axial lower end surface of the main rubber elastic body 15 and extends in the axially upward direction. A hole 74 is formed. That is, the lightened hole 74 is formed by reducing the inner diameter of the outer cylindrical member 14, and thereby, the distance between the radially opposed surfaces of the inner cylindrical member 12 and the outer cylindrical member 14, in other words, the diameter of the main rubber elastic body 15. It is formed in the portion where the thickness in the direction is reduced. By forming the lightening hole 74, the inner and outer cylindrical metal fittings 12,
When an axial load is input between the rubber elastic bodies 15
Among them, since the distance between the radially opposed surfaces of the inner and outer tube fittings 12 and 14 is small, the amount of distortion is increased and the stress generated in a portion where stress concentration is likely to occur is released, and the durability of the main rubber elastic body 15 is reduced. Is further improved.

At the lower end of the outer tube fitting 14 in the axial direction,
An annular stopper piece 72 bent radially inward and extending continuously in the circumferential direction is integrally formed. The stopper piece 72 advantageously secures a contact area of the outer tube fitting 14 with respect to a not-shown rebound stopper plate.

The embodiments of the present invention have been described in detail above, but these are merely examples.
The specific description of these embodiments should not be construed as limiting in any way.

For example, in addition to the axial and radial dimensions of the rubber elastic body 15, the depth and width of the groove 40 are appropriately changed and set in consideration of the required characteristics and input load of the anti-vibration mount. Is not limited in any way.

Further, it is not always necessary to provide the mounting plate portion 34 on the outer tube fitting 14, and the mounting plate portion 34 can be post-fixed to the outer tube fitting 14 by welding or the like.

Furthermore, the outer diameter dimensional change portion 31 (the intermediate tapered cylindrical portion 25) of the inner cylindrical fitting 12 does not necessarily need to be formed over the entire circumference in the circumferential direction, and is, for example, opposed to the radial direction. The outer diameter dimensional change portion 31 may be formed in a part of the circumferential direction, such as on both sides, or in a plurality of places.

It is not always necessary to provide the small-diameter cylindrical portion 29 of the inner cylindrical member 12. The intermediate tapered cylindrical portion 25 (the outer diameter dimensional change portion 31) is formed at the axial end of the inner cylindrical member 12. May be.

Further, in the inner cylinder fitting 12, both the axial side portions sandwiching the outer diameter dimensional change portion 31 are necessarily divided into the large-diameter cylinder portion 27 and the small-diameter cylinder portion 29 over the entire axial length.
You don't have to. That is, for example, for a shaft member whose outer diameter is constant over the entire length in the axial direction, an annular projecting portion projecting radially outward at an axial middle portion is integrally formed, and this annular member is formed. It is also possible to form the outer diameter dimension changing portion 31 by the outer peripheral surface of the protruding portion. Further, instead of integrally forming such a protruding portion with the shaft member, for example, a separately formed ring-shaped member may be externally fitted and fixed to the shaft member.

Further, in the present invention, the stopper mechanism in the bound direction and the stopper mechanism in the rebound direction are
It is not always necessary.

In addition, in the above embodiment, a specific example in which the present invention is applied to a cab mount for an automobile has been described. However, the present invention is also applicable to a sub frame mount, a member mount, a body mount, and the like for an automobile, or an automobile. Any of these can be effectively applied to a cylindrical anti-vibration mount to which an initial load is applied in an axial direction, which is adopted in various devices other than the above.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, the present invention can be implemented in a form in which various changes, modifications, improvements, and the like are made.
It goes without saying that all such embodiments are included in the scope of the present invention without departing from the spirit of the present invention.

[0058]

As is apparent from the above description, in the cylindrical anti-vibration mount having the structure according to the present invention, the reinforcing action of the cylindrical rubber elastic body by the outer diameter dimension changing portion formed on the shaft member. , The concentrated action of stress on the axial end surface of the cylindrical rubber elastic body when an axial load is input is reduced or prevented, whereby the cylindrical rubber elastic body and hence the cylindrical vibration isolator are reduced. The durability of the mount has been improved,
The intended vibration damping effect can be stably obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing a cab mount as a first embodiment of the present invention, and is a view corresponding to a II section in FIG. 2;

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a bottom view in FIG. 1;

FIG. 4 is an explanatory longitudinal sectional view showing a state in which the cab mount shown in FIG. 1 is mounted on an automobile.

FIG. 5 is an explanatory cross-sectional view showing an enlarged main part of the cab mount shown in FIG. 1;

FIG. 6 is an explanatory longitudinal sectional view showing a cab mount as a second embodiment.

FIG. 7 is an explanatory longitudinal sectional view showing a cab mount as a third embodiment.

FIG. 8 is an explanatory longitudinal sectional view showing a cab mount according to a fourth embodiment, and is a view corresponding to a VIII-VIII section in FIG. 9;

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a bottom view in FIG.

[Explanation of symbols]

 10, 60, 62, 64 Cab mount 12 Inner tube fitting 14 Outer tube fitting 15 Main rubber elastic body 25 Intermediate tapered tube portion 27 Large diameter tube portion 29 Small diameter tube portion 31 Outer diameter dimension changing portion 40 Girder groove 42 Inner peripheral corner Part 44 Outer corner

Claims (10)

[Claims] 1. A shaft member and an outer cylindrical member spaced apart from the outer peripheral side of the shaft member are connected by a cylindrical rubber elastic body interposed between opposing surfaces in a direction perpendicular to the axis. A cylindrical anti-vibration mount provided with a concave groove-shaped annular portion extending continuously in the circumferential direction with respect to one axial end surface of the rubber elastic body, wherein the axial direction of the shaft member on the side of the annular portion is provided. An outer diameter dimension changing portion is provided on an outer peripheral surface on which the cylindrical rubber elastic body is attached, which is located near an end portion, and an axial end of the shaft member on the side of the annular hollow portion is reduced in diameter. On the other hand, when the shaft member is displaced in the axial direction with respect to the outer cylindrical member toward the annular bulge portion, the annular rubber elastic body is provided with the annular bulge portion. Make sure that tensile stress acts intensively on the inner corner of the bottom of the hollow A cylindrical anti-vibration device, wherein a bottom surface shape of the annular member is set, and an inner peripheral corner of the annular member is opposed to an outer diameter change portion of the shaft member. mount. 2. The cylindrical anti-vibration mount according to claim 1, wherein the outer diameter dimension changing portion of the shaft member is a tapered outer peripheral surface inclined in an axial direction. 3. The cylindrical anti-vibration mount according to claim 1, wherein an inner diameter at the opening of the annular bulge is smaller than a maximum outer diameter at the outer diameter change portion of the shaft member. 4. The cylindrical anti-vibration mount according to claim 1, wherein the radius of curvature of the inner peripheral corner at the bottom surface of the annular bulge is smaller than the radius of curvature of the outer peripheral corner. 5. An inner peripheral corner at a bottom surface of the annular burring section has an arc-shaped cross section having a substantially constant radius of curvature.
A center point in the circumferential direction of the arc-shaped cross section is located on the outer peripheral surface of the shaft member at the outer diameter dimension changing portion or at an axial end portion side where the annular hollow portion is opened more than the outer diameter dimension changing portion. The cylindrical anti-vibration mount according to claim 1. 6. A center point in a circumferential direction of an arc-shaped cross section constituting an inner peripheral corner on a bottom surface of the annular burring portion is located on the outer diameter dimension changing portion of the shaft member in an axial projection. A cylindrical anti-vibration mount according to claim 5, 7. The cylindrical vibration isolator according to claim 1, wherein the deepest point in the axial direction of the annular portion is located on the inner peripheral side of the radial center of the annular portion. mount. 8. An axially deepest point of the annular bulge is located on the outer peripheral surface of the shaft member on the outer diameter dimension changing portion or on an axial end side where the annular bulge is opened. The cylindrical anti-vibration mount according to claim 7. 9. The outer peripheral surface shape of the shaft member and the inner peripheral surface shape of the outer cylinder member are each cylindrical, and the outer diameter dimensional change portion is continuously formed over the entire circumference in the circumferential direction of the shaft member. 9. The tubular defense device according to claim 1, wherein the annular guard portion is formed between the shaft member and the outer tubular member and has a substantially constant cross-sectional shape over the entire circumferential direction. Shake mount. 10. The cylindrical anti-vibration mount according to claim 1, further comprising a stopper mechanism for limiting an axial displacement amount of the shaft member with respect to the outer cylindrical member toward the annular portion.