Viration damper

Abstract: A vibration damper includes an overhung member or pin (1) which projects from inside an outer member or cylinder (2), and an elastic rubber body (3) between them. The outer cylinder (2), the overhung pin (1), and the body (3) are combined with each other with the adhesion strength that the body (3) has when it is vulcanized.

Description: The present invention relates to a vibration damper for use in vehicles, and more particularly to a vibration damper supported on an overhung pin. Recently, more and more vehicles are designed to be smaller in weight, height, and engine room space. To catch up with this tendency, the vibration dampers used mainly as the engine mount also show a tendency to be smaller since they are to be installed in such narrower engine rooms. Especially, with the tendency of the engine room space to be narrower, overhung type engine mounts are adopted in more and more vehicles. On the other hand, in the automobile industries, easier installation of the engine mount between the car body and engine has been considered for improved productivity. The overhung type engine mounts have so far been proved to be easiest to install. To support a heavy engine, a large overhung pin should be used. FIG. 1 is a cross-section of a conventional overhung type engine mount and FIG. 2 is a sectional view, taken along the line B-B in FIG. 1, of the engine mount. As shown, the conventional overhung type engine mount typically includes inner and outer cylinders 21 and 22, an elastic rubber body 23 formed from an unvulcanized rubber filled between the inner and outer cylinders 21 and 22 and then vulcanized to combine the cylinders with each other, and a pin 24 force-fitted in the inner cylinder 21. Since the pin 24 has to support the weight of the heavy engine, it has to be large in diameter. The diameter of the inner cylinder 21 in which the pin 24 is force-fitted should be large accordingly. While the engine mount should preferably have a smaller structure for the above reason, its inner cylinder 21 has to be large in diameter. To meet the former requirement, the elastic rubber body 23 existent between the inner and outer cylinders 21 and 22 has to be smaller in volume and the arm length of the rubber will also be reduced, which has a possibility to reduce durability of the engine mount. The increased diameter of the inner cylinder 21 is opposite to the requirement for the smaller weight and small size of parts. If the engine mount is designed to be smaller, the arm length of the elastic rubber body 23 has to be reduced correspondingly. Therefore the engine mount is desirable to be designed to be smaller without lower durability. US-A-2,362,008 discloses a resilient bearing in which a solid rubber body is molded between an outer cylindrical member and an inner cylindrical member and is in contact with both members over its entire outer and inner peripheries. The rubber body is strongly bonded to the cylindrical member during the molding and vulcanising process. The present invention has an object to overcome the above-mentioned drawbacks of the prior art by providing an overhung type vibration damper having a new structure. The above object can be attained by providing a vibration damper used as an overhung engine mount in a vehicle, as set forth in claim 1. In a vibration damper according to the present invention, an outer cylinder forming the shell of the vibration damper and an overhung pin for supporting an engine are combined directly with each other by vulcanising a vibration damping rubber put between the outer cylinder and overhung pin. Thus, the inner cylinder of the conventional vibration damper is omitted in a vibration damper according to the present invention, in which thus the free length of the elastic rubber body can be assured even with an increased diameter of the overhung pin. Also, since the inner cylinder is thus omitted, the vibration damper can be smaller in weight and in addition the manufacturing cost of the product can be reduced since the process of force-fitting the pin into the inner cylinder is not required. The elastic rubber body referred to herein may be an ordinary rubber. To provide a damping effect of a fluid, the elastic rubber body may be one in which a fluid is sealed. Note that the present invention is advantageous in that the overhung pin may be a tandem pin which is formed with different diameters. The pin could not be used in the conventional product since the pin has to be force-fitted into the inner cylinder. Namely, the omission of the inner cylinder has thus contributed to the improvement of the vibration damper according to the present invention. More specifically, a larger diameter at a central portion of the pin in contact with the elastic rubber body than the diameter at opposite ends of the pin, permits to prevent the pin from going out of the elastic rubber body. Further, waving of a central portion of the pin contributes to increase the area of contact with the elastic rubber body, thus increasing the adhesion strength to the elastic rubber body. These objects and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention when taken in conjunction with the accompanying drawings. It should be noted that the present invention is not limited to the embodiments but can freely be modified without departing from the scope thereof defined in the claims given later. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-section of a conventional vibration damper; FIG. 2 is a sectional view, taken along the line B-B in FIG. 1, of the conventional vibration damper; FIG. 3 is a cross-section of an embodiment of a vibration damper according to the present invention; FIG. 4 is a sectional view taken along the line A-A in FIG. 3; FIG. 5 is a plan view of an overhung type vibration damper according to the present invention, used as an engine mount; FIG. 6 is a side elevation of the overhung type vibration damper in FIG. 5; FIG. 7 is a front view of the overhung type vibration damper in FIG. 5; FIG. 8 is a front view, whose half is a cross-section, of another embodiment of the vibration damper according to the present invention; and FIG. 9 is a cross-section of the vibration damper in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 3, there is illustrated in the form of a cross-section of a vibration damper according to the present invention, used as an overhung type engine mount. FIG. 4 is a sectional view taken along the line A-A in FIG. 3. As seen, the vibration damper according to the present invention includes no inner cylinder, used in the conventional vibration damper, but only an overhung pin 1, an outer cylinder 2 containing the pin 1, and an elastic rubber body 3 formed from an unvulcanized rubber filled between the pin 1 and outer cylinder 2 and then vulcanized to combine the pin 1 and outer cylinder 2 with each other. The pin 1 has a projection 1a which is to be force-fitted into a bracket at the engine. As shown, the elastic rubber body 3 has axial vacancies 4 and 5 formed at the top and bottom thereof. The outer cylinder 2 is normally cylindrical and it is to be mounted on a bracket at the vehicle. The pin 1 is to be installed horizontally. The axial vacancies 4 and 5 are formed in parallel to the pin 1 in the elastic rubber body 3. Thus, the pin 1 is elastically displaceable up and down for the height of the axial vacancies 4 and 5, respectively. A portion of the elastic rubber body 3, indicated with a reference 3b, under the pin 1 has to be capable to withstand the weight and vibration of the engine. Thus, the portion 3b has a larger volume than a portion 3a of the elastic rubber body 3 above the pin 1. That is, free length H is larger on the portion 3b side. FIG. 5 is a plan view of an overhung type vibration damper according to the present invention, used as an engine mount, FIG. 6 is a side elevation of the overhung type vibration damper in FIG. 5, and FIG. 7 is a front view of the overhung type vibration damper in FIG. 5. The vehicle using the vibration damper according to the present invention is indicated with reference A. The vehicle A has a bracket 11 in which the outer cylinder 2 of the vibration damper according to the present invention is to be fitted and fixed, with the pin 1 held horizontally. Also a bracket 12 is to be force-fitted onto the projection 1a of the pin 1. A bolt 13 is screwed in the bracket 12 to hoist an engine indicated with reference B. The bolt 13 is normally directed downward. The vehicle A is to be provided with a plurality of the vibration dampers. For installation of the engine B in the engine room of the vehicle, the engine B is moved gradually from below, the bolt 13 is fitted into a mounting hole in the engine B, and a nut 14 fitted on to the bolt 13. Thereafter, the engine B is fixed by tightening the nut 14 on the bolt 13. FIG. 8 is a front view, whose half is a cross-section, of another embodiment of the overhung type vibration damper according to the present invention, and FIG. 9 is a cross-section of the vibration damper in FIG. 8. This embodiment is a so-called fluid-sealed engine-mount rubber damper. As shown, the pin 1 is enlarged in diameter at a portion thereof in contact with the elastic rubber body 3, as indicated with a reference 1b. The pin 1 is integrated with the elastic rubber body 3 by vulcanizing forming the rubber damper. The pin 1 has also the projection 1a which is to be force-fitted into a bracket (not shown), thus forming the overhung type vibration damper. As shown, the damper has formed therein vacancies 31 and 32, an orifice 33 for passage of the fluid, a rubber membrane 34, and an outer cylinder 35. As in the above, the larger diameter at a central portion (1b) of the pin 1 in contact with the elastic rubber body 3 than the diameter at opposite ends of the pin 1, permits to prevent the pint 1 from going out of the elastic rubber body 3. Further, waving (not shown) of a central portion of the pin 1 contributes to increase the area of contact with the elastic rubber body 3, thus increasing the adhesion of the pin 1 to the elastic rubber body 3.

Claims: A vibration damper used as an overhung engine mount in a vehicle, comprising: an outer cylinder (2;35) mounted on a bracket (11) at the vehicle; an overhung pin (1) disposed inside the outer cylinder (2;35), one end part (1a) of the overhung pin (1) projecting beyond one end of the outer cylinder (2;35) and being force-fitted into a bracket (12) at the engine; and a vulcanized elastic rubber body (3) disposed between the outer cylinder (2;35) and the overhung pin (1), only part of the outer periphery of the elastic rubber body (3) being in contact with the outer cylinder (2;35); characterized in that the elastic rubber body (3) is in contact with the overhung pin (1), the outer cylinder (2;35), the overhung pin (1), and the elastic rubber body (3) being combined with each other with an adhesion strength the elastic rubber body has when it is vulcanized, the portion (36) of the elastic rubber body under the pin (1) having a larger volume than the portion (3a) above the pin (1). A vibration damper as claimed in claim 1, wherein at a portion of the length of the pin (1) in contact with the elastic rubber body (3), the pin is larger in diameter at a central portion (1b) thereof than at the opposite ends. A vibration damper as claimed in claim 1, wherein at a portion of the length of the pin (1) in contact with the elastic rubber body (3), the outer surface of a central portion of the pin is waved.

Inventors: OHTSU KAZUTAKA, OKAI SHIGEKI, OHTSU, KAZUTAKA, OKAI, SHIGEKI, Ohtsu, Kazutaka, c/o Bridgestone Corporation
Applicants: BRIDGESTONE CORP, NISSAN MOTOR, BRIDGESTONE CORPORATION, NISSAN MOTOR COMPANY, LIMITED
Application year: 2000
Main classification: F16F1
IPC codes: F16F1, B60K5, F16F13