Spring devices – Resilient shock or vibration absorber – Having diverse resilient element
Reexamination Certificate
2000-08-04
2002-03-19
Butler, Douglas C. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Having diverse resilient element
C267S140130, C267S292000
Reexamination Certificate
active
06357731
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a vibration damping device including an elastic body elastically connecting two mutually spaced-apart mounting members, which are interposed between two members of a vibration system and are attached at these two mounting members to respective two members of the vibration system so as to flexibly connect these two members or mount one of these members on the other member in a vibration damping manner. More particularly, the present invention is concerned with a vibration damping device which exhibits an improved durability of the elastic body without restricting an effective free length of the elastic body.
2. Description of the Related Art
As one type of a vibration damping device interposed between two members of a vibration system so as to flexibly connect these two members or mount one of these members on the other member in a vibration damping manner, there is know a vibration damping device as disclosed in U.S. Pat. No. 6,017,024, wherein a first metallic mounting member and a second cylindrical metallic mounting member having a cylindrical portion, which are attachable to the respective two members of the vibration system, are spaced apart from each other such that an open end portion of the cylindrical portion of the second mounting member is opposed to the first mounting member, and are elastically connected to each other by an elastic body interposed therebetween. More specifically, the elastic body is bonded at its central portion to the first mounting member and a its circumferential surface to the inner circumferential surface of the cylindrical portion of the second mounting member. The vibration damping device is favorably used as an engine mount of a motor vehicle, for example.
This type of the vibration damping device is likely to suffer from a problem of cracking or other defects which occurs at the circumferential portion of the elastic body, which is bonded to the inner circumferential surface of the open end portion of the second mounting member, resulting in deterioration of durability of the elastic body. As a method to cope with this problem, there is proposed to modify the vibration damping device such that the second mounting member is formed at the open end portion of its cylindrical portion with an outward flange in order to increase a bonding surface area of the elastic body contact with respect to second mounting member, or alternatively the second mounting member includes a tapered portion which has a diameter gradually increasing toward the open end portion of the second mounting member in order to ease stress-concentration on a local portion of the elastic body. However, the use of such an outward flange or a tapered portion formed in the open end portion of the second cylindrical mounting member inevitably leads to an increase only in the diameter of the one open end portion of the second cylindrical mounting member. Since a space for accommodating the vibration damping device is limited, the diameter of the cylindrical portion of the second mounting member other than the outward flange or the tapered portion of the second mounting member is accordingly restricted, resulting in undesirable decreases in an entire volume of the elastic body and decrease in a substantial effective free length of the elastic body, in other words, the length of the elastic body connecting the first and second mounting members. Thus, the use of the outward flange or the tapered portion may possibly result in adverse influence on a spring characteristic of the elastic body. In particular, the above-indicated outward flange and the tapered portion of the second mounting member are not employable in the case where the second mounting member is fixed in the bracket such that the open end portion of the second mounting is press-fitted in the fixing bore of the bracket.
In view of the above, there has been desired to provide a vibration damping device which assures an improved durability of the circumferential portion of the elastic body which is bonded to the inner circumferential surface of the open end of the second mounting member, without increasing the diameter of the open end of the second mounting member. To meet this requirement, it is considered to modify the vibration damping device such that the open end portion of the second mounting member extends axially outward direction, so that a circumferential fillet is provided at an edge of the circumferential portion of the elastic body such that the fillet extends from the edge axially outwardly along the inner circumferential surface of the axially outward extending portion of the second cylindrical mounting member, and is bonded to this inner circumferential surface. In this case, however, the second mounting member radially outwardly disposed on the elastic body protrudes axially outward from the circumferential portion of the large-diameter portion of the elastic body. This leads to difficulty in opening the mold for molding the elastic body in a direction perpendicular to an axial direction thereof. Therefore, a degree of freedom in arranging the configuration, structure, or the like of the elastic body is significantly decreased, due to the above-indicated restriction in construction of the mold for molding the elastic body.
For instance, when the mold for molding the elastic body consists of a pair of mold halves which are butted to each other in the axial direction thereof to define therebetween a mold cavity for forming the elastic body, the configuration of the elastic body is inevitably restricted such that the diameter of the elastic body is not smaller than that of the first mounting member. This makes it impossible to protrude the peripheral portion of the first mounting member in the direction perpendicular to the axial direction from a circumferential portion of the central portion of the elastic body which is bonded to the first mounting member. That is, it is impossible to provide a circumferential fillet in an edge of the circumferential portion of the central portion of the elastic body, which edge is bonded to the peripheral portion of the first mounting member, making it difficult to provide a structure like the circumferential fillet for easing stress-concentration to the bonding portion of the elastic body with respect to the peripheral portion of the first mounting member. This drawback may possibly lead to deterioration of the durability of the elastic body.
SUMMARY OF THE INVENTION
The present invention was developed in the light of the above situation. It is therefore an object of the present invention to provide a vibration damping device having a novel structure, which is compact in size without increase of a diameter of the second mounting member, and which is capable of providing a sufficiently large free length of the elastic body. The vibration damping device also ensures an excellent durability of the elastic body, by avoiding stress concentration on local portions of the elastic body at which the elastic body is bonded to the first and second mounting members.
The above object of the invention may be achieved according to the principle of the present invention, which provides a vibration damping device interposed between two members of a vibration system for elastically connecting these two members in a vibration damping manner, the vibration damping device comprising: (a) a first mounting member and a second mounting member including a cylindrical portion, which are spaced apart from each other such that an open end portion in one of axially opposite ends of the cylindrical portion of the second mounting member is opposed to the first mounting member, and which are attachable to the two members of the vibration systems, respectively; (b) an elastic body elastically connecting the first and second mounting member such that the elastic body is bonded at a central portion thereof to the first mounting member and at a peripheral portion thereof to an inner circumferential surface of the
Kramer Devon
Rossi & Associates
Tokai Rubber Industries Ltd.
LandOfFree
Vibration damping device exhibiting high durability of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vibration damping device exhibiting high durability of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vibration damping device exhibiting high durability of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2862146