Vibration damping device

A vibration damping device including: an inner member; an outer bracket including a tubular part having an inner hole, and an end wall covering an opening of the tubular part; an intermediate member having a bent part, and first and second attachments provided at opposite sides of the bent part, while being inserted in the inner hole such that the first attachment is superposed on an inner face of the tubular part while the second attachment is axially superposed on the end wall; a main rubber elastic body elastically connecting the tubular part and an end portion of the inner member inserted in the inner hole, and elastically connecting the inner member and the attachments of the intermediate member that are bonded thereto; first and second fixtures fixing the first and second attachments to the outer bracket, respectively.

INCORPORATED BY REFERENCE

The disclosure of Japanese Patent Application No. 2018-028494 filed on Feb. 21, 2018 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vibration damping device used for an automotive engine mount, etc., for example.

2. Description of the Related Art

There has been known a vibration damping device, as a type of vibration damping connector or vibration damping support interposed between components of a vibration transmission system such as a power unit and a vehicle body, for example, so as to mutually connect the components in a vibration-damping manner. This vibration damping device has a structure in which an inner member and an outer bracket are elastically connected by a main rubber elastic body, for example.

U.S. Pat. No. 9,382,961 discloses a vibration damping device having a structure wherein an inner member and an outer tubular member are elastically connected mutually in the axis-perpendicular direction by a main rubber elastic body, while the inner member and a support piece of the outer tubular member are elastically connected in the axial direction by a connecting rubber. The outer tubular member is press-fitted into a tubular part of a bracket member. According to the vibration damping device of U.S. Pat. No. 9,382,961, not only the spring characteristics in the axis-perpendicular direction but also the spring characteristics in the axial direction can be adjusted with a great degree of freedom by providing the connecting rubber.

However, in the vibration damping device disclosed in U.S. Pat. No. 9,382,961, an end portion of the inner member and the outer tubular member are elastically connected by the main rubber elastic body with the end portion inserted in the outer tubular member, and the main rubber elastic body is thus surrounded by the outer tubular member. When the main rubber elastic body is bonded by vulcanization to the outer tubular member, the division direction of the mold of the main rubber elastic body and the like are limited by the outer tubular member, so that the degree of freedom in the shape of the main rubber elastic body is restricted.

In the vibration damping device of U.S. Pat. No. 9,382,961, it is difficult to secure the outer tubular member press-fit into the tubular part of the bracket member, for example if the inner hole of the tubular part has a hole cross sectional shape partially edged like a rectangle. It is because the stress tends to concentrate on the angular portion of the outer tubular member corresponding to the inner hole of the tubular part.

U.S. Publication No. US 2017/0211648 discloses a vibration damping device having a structure in which an elastic body is directly bonded to an inside member and a tubular part of a bracket. However, in this vibration damping device described in US 2017/0211648, for example when bonding the elastic body to the inside member and the bracket by vulcanization adhesion, it is necessary to set the large and heavy bracket in a mold for the elastic body and mold the elastic body by vulcanization. This readily leads to a problem such as reduction in productivity.

SUMMARY OF THE INVENTION

It is therefore one object of the present invention to provide a vibration damping device of novel structure which is able to set the spring characteristics in the axis-perpendicular direction and in the axial direction with a great degree of freedom, and to easily connect an inner member and an outer bracket elastically by a main rubber elastic body, irrespective of a shape of an inner hole in a tubular part of the outer bracket.

The above and/or optional objects of this invention may be attained according to at least one of the following preferred embodiments of the invention. The following preferred embodiments and/or elements employed in each preferred embodiment of the invention may be adopted at any possible optional combinations.

A first preferred embodiment of the present invention provides a vibration damping device comprising: an inner member; an outer bracket including a tubular part having an inner hole, and an end wall covering an opening of the tubular part; an intermediate member having a bent part, and a first attachment and a second attachment provided at opposite sides of the bent part, the intermediate member being inserted in the inner hole of the tubular part of the outer bracket such that the first attachment is superposed on an inner face of the tubular part while the second attachment is axially superposed on the end wall of the outer bracket; a main rubber elastic body elastically connecting the tubular part of the outer bracket and an end portion of the inner member inserted in the inner hole of the tubular part, the main rubber elastic body elastically connecting the inner member and the intermediate member that are bonded thereto with each other, the main rubber elastic body being bonded to the first attachment and the second attachment; a first fixture of the first attachment at which the first attachment is fixed to the outer bracket; and a second fixture of the second attachment at which the second attachment is fixed to the outer bracket.

According to the vibration damping device having the structure following the first preferred embodiment as described above, the intermediate member bonded to the main rubber elastic body is provided with the first attachment and the second attachment at both sides of the bent part in structure. This increases the degree of freedom in the division direction of the mold of the main rubber elastic body, for example, compared with the case where the main rubber elastic body is formed radially inside a tubular member. Owing to this, the degree of freedom in the shape of the main rubber elastic body increases. Therefore, it is possible to more efficiently realize the required characteristics, and the vibration-damping performance and the durability can improve.

In addition, the inner member and the intermediate member are bonded to the main rubber elastic body. This eliminates the need to set the outer bracket in the mold. Consequently, even if the outer bracket is large, improvement in manufacturing efficiency and the like are achieved.

With the intermediate member inserted in the inner hole of the tubular part of the outer bracket, the first attachment and the second attachment are fixed to the outer bracket by the first fixture and the second fixture, respectively. Thus, the intermediate member is easily attached to the outer bracket irrespective of the shape of the tubular part, and the fixation strength of the intermediate member to the outer bracket is secured largely.

The first attachment of the intermediate member is overlapped with the inner face of the tubular part of the outer bracket, and the first attachment is fixed to the outer bracket by the first fixture. Meanwhile, the second attachment of the intermediate member is axially overlapped with the end wall of the outer bracket, and the second attachment is fixed to the outer bracket by the second fixture. Therefore, the deformation rigidity of the intermediate member is reinforced by the outer bracket. Furthermore, since the bent part is provided between the first attachment and the second attachment of the intermediate member, the deformation rigidity of the intermediate member can be advantageously secured.

A second preferred embodiment of the present invention provides the vibration damping device according to the first preferred embodiment, wherein the first fixture of the first attachment is disposed on an opposite side to the bent part in the first attachment, and the second fixture of the second attachment is disposed on an opposite side to the bent part in the second attachment.

According to the second preferred embodiment, since the first fixture and the second fixture are disposed at mutually separated positions, the fixation strength of the intermediate member to the outer bracket can be advantageously obtained. Besides, it is easy to secure a large bonding area of the main rubber elastic body, in the first attachment and the second attachment, whereby the spring characteristics of the main rubber elastic body and the like can be set with a greater degree of freedom.

A third preferred embodiment of the present invention provides the vibration damping device according to the first or second preferred embodiment, wherein the inner hole of the tubular part in the outer bracket has a rectangular cross section.

With the third preferred embodiment, the inner hole of the tubular part can be largely secured with excellent space efficiency, and the main rubber elastic body disposed in the inner hole of the tubular part can be formed with a great degree of freedom. In addition, the first fixture and the second fixture are fixed to the outer bracket in structure. Therefore, it is possible to effectively fix the intermediate member, even to the outer bracket having an inner hole with a rectangular cross section, to which fixation of the intermediate member by press-fitting tends to be difficult.

A fourth preferred embodiment of the present invention provides the vibration damping device according to any one of the first to third preferred embodiments, wherein at least one of the first fixture and the second fixture has a clinching claw, while a clinching hole is provided in the outer bracket, and the clinching claw is inserted through the clinching hole and fastened by clinching to the outer bracket.

According to the fourth preferred embodiment, the intermediate member can be easily fixed to the outer bracket without requiring another member such as a bolt, by the clinching claw provided at the intermediate member and the clinching hole provided in the outer bracket.

A fifth preferred embodiment of the present invention provides the vibration damping device according to any one of the first to fourth preferred embodiments, wherein the first fixture extends radially outside at an axial outside of the tubular part of the outer bracket, and the first fixture is axially superposed on and fixed to the outer bracket.

With the fifth preferred embodiment, the first fixture that fixes the first attachment of the intermediate member to the outer bracket is axially overlapped with the outer bracket. Thus, the first attachment superposed on the inner face of the outer bracket can be easily fixed to the outer bracket by the first fixture.

A sixth preferred embodiment of the present invention provides the vibration damping device according to any one of the first to fifth preferred embodiments, wherein the first attachment includes a protrusion protruding to each of opposite sides in a peripheral direction of the tubular part of the outer bracket, and the main rubber elastic body is bonded to the protrusion.

According to the sixth preferred embodiment, by adjusting the protruding dimension, the axial width dimension, and the like of each protrusion, it is possible to adjust the bonding area of the main rubber elastic body to the first attachment and the inclination of the main elastic axis, etc. As a result, it is possible to tune the spring characteristics of the main rubber elastic body.

A seventh preferred embodiment of the present invention provides the vibration damping device according to the sixth preferred embodiment, wherein a protruding dimension of the protrusion changes in a part where the main rubber elastic body is bonded.

With the seventh preferred embodiment, the spring characteristics of the main rubber elastic body can be adjusted by changing the protruding dimension of each protrusion in the part where the main rubber elastic body is bonded.

According to the present invention, the intermediate member bonded to the main rubber elastic body has a structure in which the first attachment and the second attachment are provided at both sides of the bent part. Consequently, for example when the intermediate member is bonded by vulcanization to the main rubber elastic body, the degree of freedom in the division direction of the mold becomes large, thereby improving the degree of freedom in the shape of the main rubber elastic body. This makes it possible to more efficiently realize the required characteristics. Besides, the bent part is provided between the first attachment and the second attachment of the intermediate member. The first attachment of the intermediate member is superposed on the inner face of the tubular part of the outer bracket, while the second attachment of the intermediate member is axially superposed on the end wall of the outer bracket, so that the deformation rigidity of the intermediate member is advantageously secured. Furthermore, the first attachment of the intermediate member is fixed to the outer bracket by the first fixture, while the second attachment of the intermediate member is fixed to the outer bracket by the second fixture. Therefore, the fixation strength of the intermediate member to the outer bracket is secured largely.

DETAILED DESCRIPTION OF PRACTICAL EMBODIMENTS

Hereinafter, a practical embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 to 6show an automotive engine mount10as a first practical embodiment of a vibration damping device structured according to the present invention. The engine mount10has a structure in which a mount main unit12is attached to an outer bracket14. As shown inFIGS. 7 to 12, the mount main unit12has a structure wherein an inner member16and an intermediate member18are elastically connected by a main rubber elastic body20. In the following description, as a general rule, the up-down direction means the up-down direction inFIG. 1, the front-back direction means the direction orthogonal to the paper face inFIG. 1, and the left-right direction means the left-right direction inFIG. 1.

More specifically, the inner member16is a high rigidity member made of metal or the like. As shown in enlarged views ofFIGS. 13 to 17, the inner member16integrally includes a fastening portion22in a thick plate shape and a bonded portion24projecting backward from the fastening portion22. In addition, a plurality of bolt holes26are formed through the fastening portion22so that the fastening portion22is fixed to a not-shown power unit by not-shown bolts inserted through the bolt holes26. However, the concrete structure of the fastening portion22shown in this practical embodiment is merely an example and can be changed as appropriate according to the attachment structure on the power unit side. Meanwhile, the bonded portion24has a substantially rectangular block shape as a whole. Additionally, a convex part28is formed integrally with the bonded portion24, while protruding toward the back side opposite to the fastening portion22. The inner member16can be obtained by molding, for example.

As shown inFIG. 12, the intermediate member18has a cross sectional shape bent in a substantially L-shape. As shown also inFIGS. 18 to 22, the intermediate member18has a first attachment32and a second attachment34at opposite sides of a bent part30. The intermediate member18of the present practical embodiment is integrally formed as a whole with a press fitting.

The first attachment32has a flat plate shape which expands substantially orthogonally to the up-down direction, and a first fixture36is integrally formed at the end portion opposite to the bent part30. The first fixture36has a width dimension extending as long as almost the entire flat central portion in the width direction in the first attachment32. The first fixture36extends downward, i.e., radially outside, at the front end portion which is the end portion on the opposite side to the bent part30in the first attachment32. In this practical embodiment, a folded part38is formed in the middle portion of the first attachment32in the up-down direction, and the lower portion of the first attachment32below the folded part38is located on the back side (the left side inFIG. 22) of the upper portion thereof. Besides, bolt holes40are formed through the lower portion of the first fixture36below the folded part38, in the front-back direction. In the present practical embodiment, two bolt holes40,40are provided apart from each other in the left-right direction. In the present practical embodiment, the folded part38is provided in the first fixture36, whereby the front end portion of the first attachment32, the upper portion of the first fixture36, and the folded part38constitute a concave groove structure that opens backward and extends in the left-right width direction. This concave groove structure improves the deformation rigidity of the first fixture36and also prevents the head portions of later-described bolts92inserted through the bolt holes40from largely projecting forward. However, the folded part38is not indispensable in the present invention.

Moreover, protrusions42protruding to the left-right outside are respectively provided at both left and right end portions of the first attachment32. The protrusions42are provided at the front side portion of the first attachment32, and they gradually incline upward as they go toward the left-right outside. The protrusions42gradually rise as they go toward the left-right outside, and each has a curved shape whose inclination angle increases relative to the left-right direction. The protrusions42extend in the peripheral direction of an inner hole66, roughly corresponding to the corner portion of the inner hole66of the outer bracket14which will be described later. Furthermore, in the present practical embodiment, both the protruding width dimension in the left-right direction and the protruding height dimension in the upward direction as the protruding dimension of the protrusion42from the first attachment32are larger in the front side than in the back side. The protruding dimension of the protrusion42may be different in at least one of the left-right direction and the upward direction.

The second attachment34has a flat plate shape which expands substantially orthogonally to the front-back direction, and a second fixture44is provided at the upper end portion which is the end portion on the opposite side to the bent part30. The second fixture44is in the form of a plate whose dimension in the left-right direction is smaller than that of the lower portion of the second attachment34. In the present practical embodiment, the second fixture44has clinching claws46, at both sides in the left-right direction of the upper end portion thereof. The clinching claw46has a roughly rectangular plate shape and extends to the back side, at both left and right end portions of the second fixture44. The clinching claw46tilts without being orthogonal to any of the up-down direction and the left-right direction. In this practical embodiment, a step48is provided at the middle portion of the second attachment34, and the portion of the second attachment34upper than the step48is the second fixture44. By forming this step48, the deformation rigidity of the second attachment34improves, and the second fixture44is located behind the lower portion of the second attachment34.

The bonded portion24of the inner member16is arranged to face the first attachment32of the intermediate member18in the up-down direction and it is arranged to face the second attachment34of the intermediate member18in the front-back direction. The opposing faces of the bonded portion24of the inner member16and each of the first and second attachments32,34of the intermediate member18are elastically connected by the main rubber elastic body20. The fastening portion22of the inner member16protrudes forward from the main rubber elastic body20to be exposed.

The main rubber elastic body20integrally includes a first connecting portion50elastically connecting the bonded portion24of the inner member16and the first attachment32of the intermediate member18in the up-down direction. Additionally, the main rubber elastic body20integrally includes a second connecting portion52elastically connecting the bonded portion24of the inner member16and the second attachment34of the intermediate member18in the front-back direction.

The first connecting portion50is formed in a thick, almost plate shape spreading substantially orthogonally to the front-back direction. As shown inFIG. 7, the first connecting portion50is tapered such that the left-right dimension gradually increases as it goes toward the lower side. Further, a through hole54is formed penetrating in the front-back direction through the left-right central portion of the first connecting portion50, so that a pair of rubber legs56,56are formed at both left and right sides of the through hole54while extending in such directions that they are inclined to the left-right outside as they go to the lower side. The upper end of the first connecting portion50is bonded by vulcanization to the bonded portion24of the inner member16, while the lower end thereof is bonded by vulcanization to the first attachment32of the intermediate member18. The first connecting portion50of the main rubber elastic body20is bonded to the front portion of the first attachment32, and the left and right ends of the lower end portion of the first connecting portion50are bonded to the protrusions42,42of the first attachment32. The upper face of the back portion of the first attachment32is covered by a covering rubber58formed integrally with the first connecting portion50. The covering rubber58is also formed to cover the lower face of the back portion of the first attachment32and the back face of the lower portion of the second attachment34.

As shown inFIGS. 11 and 12, the second connecting portion52has a nearly inclined plate shape extending in the front-back direction and gradually inclining downward as it goes backward. In the second connecting portion52, the front end portion is bonded by vulcanization to the bonded portion24of the inner member16, while the back end portion is bonded by vulcanization to the second attachment34of the intermediate member18. Since the front end portion of the second connecting portion52is bonded to the back face of the bonded portion24where the convex part28protrudes, the spring characteristics of the second connecting portion52is adjusted by the convex part28.

An upper stopper rubber60formed integrally with the main rubber elastic body20is bonded to the upper face of the bonded portion24of the inner member16. Side stopper rubbers62,62formed integrally with the main rubber elastic body20are bonded to the left-right outer faces of the bonded portion24of the inner member16.

As shown inFIGS. 1 to 6, the outer bracket14is attached to the mount main unit12having such a structure. The outer bracket14is a high rigidity member made of metal such as iron, for example, and has a tubular part64.

As also shown inFIGS. 23 and 24, the tubular part64is formed in a substantially rectangular tubular shape with its corner portions rounded. The tubular part64has the inner hole66having a generally rounded rectangular cross section while penetrating in the front-back direction. In the tubular part64of this practical embodiment, the front end of the upper side portion in the inner face has an inclined face which is inclined upward as it goes to the front side. When inserting the mount main unit12into the tubular part64as described later, the upper end portion of the mount main unit12is hardly caught by the front end of the tubular part64.

Further, a connecting member68is fixed to the tubular part64by a means such as welding. The connecting member68is secured to the left and right side faces and the lower face in the outer peripheral face of the tubular part64and spreads to the left and right sides and the lower side of the tubular part64. The upper end portion of the connecting member68is bent on the left side of the tubular part64and extends out backward. In addition, the connecting member68is provided with a fixture receiving seat70that is superposed on the front face of the connecting member68in the lower side than the tubular part64so as to project forward. Two bolt holes are formed penetrating the fixture receiving seat70in the front-back direction, and nuts72,72are fixed to the back face of the fixture receiving seat70by a means like welding. Screw holes of the nuts72,72are opened to the front face of the fixture receiving seat70through bolt holes penetrating the fixture receiving seat70.

A first fastening member74is fixed to the tubular part64and the connecting member68by a means such as welding. The first fastening member74has an upper end wall76as an end wall that covers the upper portion of the back opening of the tubular part64and a bolt hole78penetrating the upper end portion thereof in the thickness direction. In the upper end wall76of the first fastening member74, clinching holes80,80corresponding to the clinching claws46,46of the intermediate member18are formed through it in the front-back direction. The first fastening member74is fixed to the back end portion of the tubular part64and the upper end portion of the connecting member68.

A second fastening member82is fixed to the tubular part64and the connecting member68by a means such as welding. The second fastening member82has a lower end wall84that covers the lower portion of the back opening of the tubular part64. A fastening piece86that is located below the lower end wall84is provided with bolt holes88formed penetrating through both left and right end portions thereof in the front-back direction. The second fastening member82is fixed to the back end portion of the tubular part64and the lower end portion of the connecting member68. In the second fastening member82of the present practical embodiment, the lower end wall84and the fastening piece86are disposed at different positions in the front-back direction. Thus, the second fastening member82has a stepped plate shape integrally formed by bending a blank plate through press working, with its deformation rigidity improved. Besides, in the present practical embodiment, bolt holes90are formed through the left and right end portions of the bent section connecting the lower end wall84and the fastening piece86of the second fastening member82.

It is possible to change as appropriate the specific shapes of the first fastening member74and the second fastening member82and the arrangement and the number of the bolt holes78,88,90in the first fastening member74and the second fastening member82, and the like, according to the mounting structure on the vehicle body side, the specific shapes of the tubular part64and the connecting member68, and the like.

As shown inFIG. 25, the outer bracket14having such a structure is attached to the mount main unit12by inserting the mount main unit12from the front side into the inner hole66of the tubular part64. Specifically, the intermediate member18of the mount main unit12is inserted without being press-fitted into the inner hole66of the tubular part64of the outer bracket14. As shown inFIG. 6, the first attachment32of the intermediate member18is superposed on the lower side portion in the inner face of the tubular part64, while the second attachment34of the intermediate member18is axially superposed on the upper end wall76, at the upper end portion thereof constituting the second fixture44. The first fixture36of the intermediate member18is axially superposed on the front face of the fixture receiving seat70provided in the connecting member68. The bolts92,92are inserted through the bolt holes40,40of the first fixture36and threaded onto the nuts72,72welded to the back face of the fixture receiving seat70. By so doing, the first attachment32of the intermediate member18is fixed to the outer bracket14. Moreover, the clinching claws46provided in the second fixture44of the intermediate member18are inserted through the clinching holes80of the upper end wall76, and the portions protruding rearward beyond the upper end wall76are folded. Thus, the clinching claws46are fastened by clinching to the upper end wall76such that the clinching claws46are engaged therein axially, so that the second attachment34of the intermediate member18is fixed to the outer bracket14.

In this manner, by fixing the first attachment32and the second attachment34to the outer bracket14, the intermediate member18is fixed to the outer bracket14, thereby constituting the engine mount10of the structure wherein the outer bracket14is mounted to the mount main unit12. In the engine mount10, with the bonded portion24, which constitutes the end portion of the inner member16, inserted in the inner hole66of the tubular part64of the outer bracket14, the inner member16and the tubular part64of the outer bracket14are elastically connected to each other by the main rubber elastic body20.

For the engine mount10, the inner member16is attached to a not-shown power unit by not-shown bolts inserted through the respective bolt holes26provided in the fastening portion22. Meanwhile, the outer bracket14is attached to a not-shown vehicle body, by a not-shown bolt inserted through the bolt hole78of the first fastening member74and the bolt holes88,90of the second fastening member82. As a result, the power unit and the vehicle body of the automobile are connected by the engine mount10in a vibration-damping manner.

When the outer bracket14is attached to the mount main unit12, the bonded portion24, which is the back end portion of the inner member16of the mount main unit12, is inserted in the tubular part64of the outer bracket14. Thus, the inner member16of the mount main unit12is disposed radially inside the tubular part64. As a result, the bonded portion24of the inner member16and the tubular part64of the outer bracket14get into contact via the upper stopper rubber60, thereby constituting a rebound stopper that limits the displacement amount of the inner member16to the upper side relative to the outer bracket14. Also, the bonded portion24of the inner member16and the tubular part64of the outer bracket14get into contact via the side stopper rubbers62, thereby constituting a side stopper that limits the relative displacement amount in the left-right direction of the inner member16and the outer bracket14.

In the engine mount10having the structure according to the present practical embodiment as described above, the intermediate member18has a bent plate shape in which the first attachment32and the second attachment34are integrally continuous by the bent part30. Therefore, when the main rubber elastic body20is formed as an integrally vulcanization molded component incorporating the intermediate member18, the division direction of the mold of the main rubber elastic body20is hardly limited by the intermediate member18, whereby the degree of freedom in the shape of the main rubber elastic body20becomes greater. Therefore, the degree of freedom in tuning of the spring characteristics of the main rubber elastic body20is accordingly increased, and the required vibration-damping characteristics can be realized more efficiently. In particular, the intermediate member18of the present practical embodiment has a plate shape that is bent in an L character shape, so that it is possible to divide the mold of the main rubber elastic body20in the up-down direction, the front-back direction, and the left-right direction. Thus, it is possible to design the main rubber elastic body20with a greater degree of freedom.

For the engine mount10, the first attachment32of the intermediate member18is overlapped with the inner face of the tubular part64of the outer bracket14in an indirect contact state via the covering rubber58, while the second fixture44of the second attachment34of the intermediate member18is overlapped with the upper end wall76of the outer bracket14in a direct contact state. As a result, the deformation rigidity of the intermediate member18is reinforced by the outer bracket14. Therefore, sufficient deformation rigidity is ensured although the intermediate member18is in a plate form, and the intermediate member18can be thinned in order to lighten it.

Since the bent part30is provided in the intermediate member18, the deformation rigidity of the intermediate member18itself also improves. In addition, the first attachment32and the second attachment34provided on both sides of the bent part30are fixed to the outer bracket14respectively by the first fixture36and the second fixture44. As a result, the fixation strength of the intermediate member18to the outer bracket14can be obtained largely.

In addition, the first fixture36and the second fixture44are provided on both sides of the bent part30separately from the bent part30. Particularly in the present practical embodiment, the first fixture36is provided at the lower end portion and the front end portion of the intermediate member18, while the second fixture44is provided at the upper end portion and the back end portion of the intermediate member18. Therefore, a large distance is secured between the first fixture36and the second fixture44, so that the fixation strength of the intermediate member18to the outer bracket14and the load bearing capability in relation to an input can be advantageously obtained.

The engine mount10has a structure wherein the intermediate member18inserted in the inner hole66of the tubular part64is fastened by clinching and using the bolts to the outer bracket14at the first and second fixtures36,44. Consequently, although the inner hole66of the tubular part64of the outer bracket14has a substantially rectangular cross sectional shape, stress concentration, etc. on the corner portions, which is a problem in press-fit securing, cannot occur. Therefore, it is easy to assemble the mount main unit12and the outer bracket14, and it is possible to prevent the intermediate member18from being damaged by the stress in the assembly.

The first fixture36of the intermediate member18is provided axially outside the tubular part64of the outer bracket14, whereby the first attachment32overlapped with the inner face of the tubular part64can be readily fixed to the outer bracket14.

The clinching claws46provided in the second fixture44of the intermediate member18are inserted through the clinching holes80formed in the upper end wall76of the outer bracket14. The clinching claws46are bent and axially engaged in the upper end wall76, whereby the second attachment34of the intermediate member18is fixed to the outer bracket14. Therefore, a separate fixing member such as a bolt is unnecessary in the second fixture44, and the second attachment34of the intermediate member18can be easily fixed to the outer bracket14.

Especially in the present practical embodiment, since the clinching claw46is in the form of a plate which spreads inclining relative to both the up-down direction and the left-right direction. This improves the load bearing capability in relation to inputs in the up-down direction and the left-right direction, in the clinching fastening structure of the second fixture44using the clinching claws46.

Protrusions42protruding outward in the left-right direction are provided at both left and right end portions of the first attachment32in the intermediate member18, and each has a curved shape that inclines upward as it goes to the left-right outside. Thus, the spring characteristics of the first connecting portion50is adjusted by bonding the first connecting portion50of the main rubber elastic body20to the left-right inner faces of the protrusions42. In particular, the protruding dimension, the inclination angle, the axial width dimension, and the like of the protrusion42are set as appropriate in the part where the first connecting portion50is bonded. This makes it possible to efficiently adjust the spring characteristics of the first connecting portion50. In the present practical embodiment, the first connecting portion50is bonded to the almost entire protrusion42, and the front portion of the protrusion42is larger in protruding dimension than the back portion thereof, whereby the spring characteristics of the first connecting portion50is adjusted.

The practical embodiment of the present invention has been described in detail above, but the present invention is not limited by the specific description of the practical embodiment. For example, as long as the intermediate member is fixed in a state of being inserted without being press-fitted in the tubular part64of the outer bracket14, it may have a third attachment vertically opposed to the first attachment32and a fourth attachment connected to the left-right end portions of the first and second attachments32,34, etc., in addition to the first attachment32and the second attachment34. In summary, as long as the intermediate member has a portion provided with the first attachment and the second attachment on both sides of the bent part, the specific structure of the other portions can be changed as appropriate. It is not always necessary that the first attachment32is overlapped with the lower portion of the tubular part64. For example, the first attachment32may be overlapped on the inner face of the upper side portion of the tubular part64.

Also, the inner hole of the tubular part of the outer bracket is not necessarily limited to one with a substantially rectangular cross section, and it is possible to employ other hole cross sectional shapes including an oval cross section, for example. The first attachment of the intermediate member to be overlapped with the inner face of the tubular part has a shape that can be superposed on the inner face of the tubular part depending on the cross sectional shape of the inner hole of the tubular part.

In addition, the fixation structures of the first fixture36and the second fixture44to the outer bracket14shown in the above practical embodiment are merely examples, and they are not especially limited. Specifically, for example, it is possible to use a clinching fastening structure using a clinching claw in the first fixture, and it is also possible to use a bolt fixing structure in the second fixture. In addition to the clinching and bolt fixing as described above, it is also possible to employ a fixation structure with rivets or a fixation structure by welding, and the like.

The first fixture is not necessarily provided to project outward in the axial direction with respect to the tubular part of the outer bracket. Alternatively, it is possible that the first fixture is provided in the face of the first attachment to be superposed on the inner face of the tubular part so that the first attachment is fixed to the peripheral wall portion of the tubular part by the first fixture. In the above-described practical embodiment, the first and second fixtures are provided at the end portions of the first and second attachments opposite to the bent part, whereby the fixation strength of the first and second attachments to the outer bracket improves and the reinforcement effect improves. However, the technical effect such as improvement in the fixation strength to the outer bracket can be achieved effectively to some extent, if the first and second fixtures are provided in the opposite sides to the bent part in the first and second attachments, that is, locations closer to the ends opposite to the bent part in the first and second attachments than to the bent part.

The number, arrangement, shape, and the like of the clinching claws constituting the second fixture can be changed. For example, it is possible as well that a clinching claw is provided at each of the left and right end portions and the upper end portion of the second attachment so that the second attachment and the outer bracket are fixed by the clinching claws at three positions.

Further, in the above-described practical embodiment, there is shown, as an example, the structure wherein the second attachment34is superposed and abutted on the upper end wall76, which is the end wall of the outer bracket14, in the upper end portion thereof, i.e., the second fixture44. Alternatively, the second attachment may be superposed and abutted on the end wall, in a generally whole face thereof, or in a section thereof separate from the second fixture.

Moreover, the first attachment may be overlapped with the inner face of the tubular part of the outer bracket in a direct contact state. Furthermore, the second attachment may be overlapped with the end wall of the outer bracket, in an indirect contact state via a rubber or the like.