Vibration damping bush mounting structure

Abstract

This eliminates the twisting of the vibration-damping rubber and the resulting reaction force. [Solution] A vibration-damping bush 4 is attached to the support member 1 and the object to be fixed 2 by fitting the vibration-damping rubber 7 onto the outer circumference of a cylindrical member 5 having a bolt insertion hole 8 in its center, and having a disc-shaped collar portion 9 on one end of the cylindrical member 5. The vibration-damping bush 4 is attached to the support member 1 and the object to be fixed 2 by fitting the vibration-damping rubber 7 into a through hole 3 formed in the support member 1, and screwing a bolt 12 inserted into the bolt insertion hole 8 into the object to be fixed 2 supported by the support member 1. The cylindrical member 5 is fitted to the support member 1 with the collar portion 9 pressed against the object to be fixed 2, and the bolt 12 is inserted into the bolt insertion hole 8 from the end opposite to the collar portion 9 and screwed into the object to be fixed 2. A retaining member 11, which is larger than the opening diameter of the through hole 3, is fixed to the outer circumference of the end of the cylindrical member 5 that protrudes from the vibration-damping rubber 7 on the opposite side of the collar portion 9.

Description

Technical Field

[0001] The present invention relates to a structure for supporting a predetermined device by a vibration isolation bush, and particularly to a structure for attaching the vibration isolation bush to a support member such as a bracket.

Background Art

[0002] An example of a structure for supporting an in-vehicle device using a vibration isolation bush is described in Patent Document 1. The structure described in Patent Document 1 is a structure for supporting an inverter on a transaxle. A plate-like bracket is attached to the transaxle, a vibration isolation bush is fitted into a portion on the tip side of the bracket, and a bolt passing through the vibration isolation bush is screwed into the inverter. Therefore, the inverter is supported by the vibration isolation bush attached to the bracket via a bolt integrated with it.

[0003] The vibration isolation bush is configured by sandwiching vibration isolation rubber between an inner sleeve and an outer sleeve arranged concentrically with respect to the inner sleeve. Each sleeve has a flange-like portion, that is, a collar, extending outward in the radial direction on one end side in the axial direction. The vibration isolation rubber is also filled between those collars and is configured to perform buffering in the axial direction. Therefore, the vibration isolation bush inserts the so-called tip portion on the side opposite to the end portion provided with the collar into the inside of a through hole formed in the bracket toward the inverter. In that state, a bolt is inserted into the inside of the inner sleeve, and the tip portion is screwed into the inverter, whereby the vibration isolation bush is fixed to the inverter.

Prior Art Documents

Patent Documents

[0004] <00,00019>

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When bolts are tightened to secure the vibration-damping bushing to the inverter and bracket, the vibration-damping rubber is compressed between the collars, and simultaneously, the vibration-damping rubber undergoes elastic deformation, resulting in internal stress filling the space between the inner sleeve and outer sleeve. The resulting reaction force pushes the bolt back, creating friction between the bolt head and the collar of the inner sleeve. This friction acts in the opposite direction to the tightening of the bolt. Furthermore, while the inner sleeve tends to rotate in the direction of the bolt's rotation due to the friction with the bolt, the outer sleeve is fitted and fixed to the bracket, causing twisting in the vibration-damping rubber. Additionally, the tip of the inner sleeve is pressed against the side of the inverter, creating friction at the point of contact. This friction acts in a direction that prevents the inner sleeve from rotating.

[0006] As described above, in a structure where a bolt is tightened to fix the vibration-damping bush, the vibration-damping rubber inevitably twists. The torque caused by this twist acts in the direction of loosening the bolt after it has been tightened. In conventional mounting structures known from Patent Document 1, etc., the collar of the inner sleeve is pressed by the bolt head, either directly or via a washer, whereas in this case, only the tip of the inner sleeve abuts against the outer surface of the inverter to which it is fixed. In other words, the frictional force between the collar of the inner sleeve, which is subjected to the reaction force due to the twisting of the vibration-damping rubber, and the bolt head is greater than the frictional force acting between the tip of the inner sleeve and the outer surface of the inverter in the direction of stopping the rotation of the inner sleeve. Therefore, after the vibration-damping bush is installed, the torque caused by the twisting of the vibration-damping rubber continues to act on the bolt in the direction of loosening, which may cause insufficient or uncertain fixing of the inverter via the vibration-damping bush. In addition, the torque caused by the twisting of the vibration-damping rubber may cause the bracket side to rotate, resulting in misalignment.

[0007] This invention was made in view of the above technical problems, and aims to provide a mounting structure for an anti-vibration bush that can eliminate the twisting of the anti-vibration rubber and the reaction force caused thereby. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a mounting structure for a vibration-damping bush, which is attached to a support member and a fixed object by fitting the vibration-damping bush into a through hole formed in a support member and screwing a bolt inserted into the bolt insertion hole into the fixed object supported by the support member, wherein the cylindrical member is fitted into the support member with the collar pressed against the fixed object, the bolt is inserted into the bolt insertion hole from the end opposite to the collar and screwed into the fixed object, and a retaining member larger than the opening diameter of the through hole is fixed to the outer circumference of the end of the cylindrical member that protrudes from the vibration-damping rubber on the opposite side of the collar. [Effects of the Invention]

[0009] According to the present invention, the vibration-damping bush contacts the object to be fixed via a collar portion, and the tip of the cylindrical member contacts the bolt head or the washer between the bolt head and the bush. Therefore, the frictional force generated between the bush and the fixing member is greater than the frictional force generated between the tip of the cylindrical member and the bolt head. As a result, when the bolt is tightened, the cylindrical member comes into contact with the object to be fixed and the bolt head, and torque is generated due to friction at those points. However, since the frictional force on the object to be fixed is greater than the frictional force on the bolt head side, the cylindrical member does not rotate even when the bolt is rotated. In other words, twisting does not occur in the vibration-damping rubber, and the effect of shifting the position of the support member can be avoided. [Brief explanation of the drawing]

[0010] [Figure 1]This is a front view showing one embodiment of the present invention. [Figure 2] This is a cross-sectional view. [Modes for carrying out the invention]

[0011] Next, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the embodiments described below are merely examples of how the present invention can be implemented and do not limit the invention.

[0012] Figure 1 shows an embodiment of the present invention, and Figure 2 shows a cross-sectional view thereof. The example shown here is an application of the present invention to a structure for fixing a casing for a charger to a bracket provided on the upper side of a power control unit in an electric vehicle. In Figures 1 and 2, reference numeral "1" indicates a bracket corresponding to a support member, and reference numeral "2" indicates a casing for a charger corresponding to the object to be fixed.

[0013] A through hole 3 is formed in a predetermined location in the bracket 1. A vibration-damping bush 4 is inserted into this through hole 3. The basic structure of the vibration-damping bush 4 is almost the same as that of conventionally known vibration-damping bushes, and is constructed by filling a vibration-damping rubber 7 between a metal inner sleeve 5 and an outer sleeve 6 that is arranged concentrically with respect to the inner sleeve 5.

[0014] The inner sleeve 5 corresponds to the cylindrical member in the embodiment of the present invention, and as shown in Figure 2, it has a cylindrical portion with a bolt insertion hole 8 formed in the center, and a flange-shaped or disc-shaped collar portion 9 provided at one end of the cylindrical portion so as to extend radially outward. The outer sleeve 6 has a cylindrical portion with an inner diameter larger than the outer diameter of the cylindrical portion of the inner sleeve 5, and a flange-shaped collar portion 10 provided at one end in the axial direction (the end on the collar portion 9 side) so as to extend radially outward. The axial length of the cylindrical portion of the outer sleeve 6 is about the length of the through hole 3 formed in the bracket 1, and therefore shorter than the length of the cylindrical portion of the inner sleeve 5. The outer diameters of the collar portions 9 and 10 are approximately the same, and in the example shown in Figure 2, the outer diameter of the collar portion 9 in the inner sleeve 5 is somewhat smaller than the outer diameter of the collar portion 10 in the outer sleeve 6. Vibration-damping rubber 7 is filled between the cylindrical portions of each sleeve 5 and 6 or between the collar portions 9 and 10. In other words, the vibration-damping rubber 7 connects each of the sleeves 5 and 6, making them a single unit.

[0015] The cylindrical portion of the inner sleeve 5 has a length that protrudes axially from the through hole 3 in the bracket 1 when the vibration-damping bush 4 is inserted into the through hole 3. A plate 11 is provided on the outer circumference of the end of the cylindrical portion opposite to the collar portion 9. The plate 11 corresponds to the retaining member in the embodiment of the present invention, and this plate 11 is made of a metal plate with an outer diameter larger than the inner diameter (opening diameter) of the through hole 3 in the bracket 1. The means for attaching the plate 11 to the inner sleeve 5 can be any appropriate means as needed, and in the example shown in Figures 1 and 2, the plate 11 is press-fitted into the tip of the cylindrical portion of the inner sleeve 5.

[0016] The mounting structure for the vibration-damping bush in the embodiment of the present invention is characterized by fitting the vibration-damping bush 4 into the through hole 3 of the bracket 1 such that the collar portion 9 of the inner sleeve 5 is located on the side of the casing 2 which is the object to be fixed, and then fixing the vibration-damping bush 4 to the casing 2 with a bolt 12. Specifically, first, with the plate 11 not attached, the vibration-damping bush 4 is inserted into the through hole 3 of the bracket 1 from the casing 2 side. In this state, the plate 11 is press-fitted into the tip of the cylindrical portion of the inner sleeve 5 and fixed, and the casing 2 is placed inside the bracket 1. If the casing 2 is to be attached to the upper side of a power control unit (not shown) after the bracket 1 has been attached to the casing 2, the bracket 1 with the vibration-damping bush 4 attached is positioned along the casing 2. Note that the direction of insertion of the vibration-damping bush 4 into the bracket 1 in this manner is opposite to the conventional insertion direction.

[0017] With the bolt insertion hole 8 of the inner sleeve 5 aligned with the threaded hole in the casing 2, the collar portion 9 of the inner sleeve 5 is pressed against the side of the casing 2. In this state, the bolt 12 is inserted into the bolt insertion hole 8 from the end of the inner sleeve 5 where the plate 11 is attached, and the tip is screwed into the threaded hole in the casing 2. In the example shown in Figure 2, a washer 13 is fitted onto the bolt 12.

[0018] When the bolt 12 is further screwed in, the washer 13 contacts the tip of the cylindrical portion of the inner sleeve 5, pushing the vibration isolator bush 4 toward the casing 2. Along with this, the collar portion 9 is gradually pressed more strongly against the side surface of the casing 2, and a frictional force is generated between them as the bolt 12 is rotated. Similarly, the washer 13 and the tip of the cylindrical portion of the inner sleeve 5 gradually come into stronger contact, and a frictional force is generated between them as the bolt 12 is rotated. Among the contact areas of the inner sleeve 5 with the mating member, the area on the side of the collar portion 9 is large, and the area on the tip side of the cylindrical portion is small. Therefore, the torque acting on the inner sleeve 5 as the bolt 12 is rotated is smaller than the resistance force acting between the collar portion 9 and the casing 2. Therefore, in the above-described mounting structure, even if the bolt 12 is rotated, the inner sleeve 5 does not rotate, so it is possible to avoid the vibration isolator rubber 7 from being twisted or generating a reaction force that rotates the bolt 12 in the loosening direction. Also, displacement of the position on the bracket 1 side can be avoided.

[0019] Also, since the vibration isolator bush 4 in the embodiment of the present invention includes the above-described plate 11, when an external force acts so that the bracket 1 and the casing 2 are separated, the opening end of the through hole 3 in the bracket 1 is caught by the above-described plate 11. Therefore, it is possible to prevent the so-called bush pull-out in which the vibration isolator bush 4 comes out of the bracket 1.

[0020] As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented within the range that can achieve the object of the present invention. For example, a vibration isolator bush that does not have the above-described outer sleeve 6 may be used. Also, the member for preventing pull-out may be a member that also serves as a washer for the bolt, in addition to the above-described plate.

Description of Reference Numerals

[0021] 1 Bracket 2 Casing 3 Through hole 4 Vibration isolator bush 5 Inner sleeve 6 Outer sleeve 7 Vibration isolation rubber 8 Bolt insertion hole 9, 10 Color part 11 Plate 12 Bolt 13 Washer

Claims

[Claim 1] A vibration-damping bush is provided on the outer circumference of a cylindrical member having a bolt insertion hole in its center, and a disc-shaped collar portion extending radially outward from one end of the cylindrical member. The vibration-damping bush is attached to the support member and the object to be fixed by fitting the vibration-damping rubber into a through hole formed in the support member and screwing a bolt inserted into the bolt insertion hole into the object to be fixed supported by the support member, thereby providing a mounting structure for the vibration-damping bush. The cylindrical member is fitted into the support member with the collar portion pressed against the object to be fixed, The bolt is inserted into the bolt insertion hole from the end opposite to the collar portion and screwed into the object to be fixed. A retaining member, larger than the opening diameter of the through hole, is fixed to the outer circumference of the end of the cylindrical member that protrudes from the vibration-damping rubber on the side opposite to the collar portion. A mounting structure for vibration-damping bushings characterized by the following features.

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