Brakes – Plastic deformation or breakage of retarder element
Reexamination Certificate
1999-03-12
2001-10-09
Butler, Douglas C. (Department: 3613)
Brakes
Plastic deformation or breakage of retarder element
C188S321110
Reexamination Certificate
active
06298962
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a member for use with an arm used as an automotive suspension arm, an engine mount, a link, a frame, and so on.
2. Description of the Related Art
For example, a member for use with an arm such as an upper arm, a lower arm, a trailing arm, or a torsion bar is mounted in an automobile. Such a member for use with an arm is generally composed of a metallic rodlike body and joints formed at both ends of the rodlike body. The joints are connected to other automotive members. One example of these joints is a bushing mount having bushing-holding hole in which a bushing is fitly held. Other examples include a yoke and a ball joint.
A method of mounting this member for use with an arm to other automotive member is described by taking an example in which the aforementioned joint is the above-described bushing mount. The bushing-holding hole in the bushing mount is shaped circularly. A cylindrical anti-vibration bushing including a rubber elastic member is fitly held in the hole. The member for the arm is mounted to the other automotive member via this bushing.
Such members for arms come in various kinds. When a collision takes place, some of them are required to deform so as to mitigate the impact if a load of more than a given value is applied.
In particular, when an automobile crashes, a load is applied to the bushing in the direction to bring the bushing and the member closer to each other it follows that an axial compressive load is applied to the member for the arm. The member for the arm receives the axial compressive load and is required to deform, so that the member can mitigate the impact in the crash.
SUMMARY OF THE INVENTION
In view of the technical background as described above, the present invention has been made.
It is an object of the present invention to provide a member for use with an arm capable of mitigating impact in a collision.
Other objects and features of the invention will appear in the course of the description thereof, which follows.
The above-described object is achieved in accordance with the teachings of the invention by a member or use with an arm, the member comprising a rodlike body made of a metal. Joints are formed in parts of the rodlike body. This member has a deformable portion that permits the member to deform easily when an axial compressive load is applied.
In particular, when an automobile or any other vehicle having the arm mounted therein crashes, an axial compressive load is applied to the member for use with the arm. Since the member in accordance with the invention has the deformable portion that facilitates deformation of the member when the axial compressive load is applied. Therefore, when the vehicle collides, the axial compressive load deforms the member for the arm in the deformable portion. This deformation mitigates the impact in a crash.
An example of the deformable portion is a crushed wall portion of the rodlike body formed in a longitudinally intermediate portion of the rodlike body of the member. In this case, the axial compressive load buckles the rodlike body of the arm in the crushed wall portion. This buckling mitigates the impact in a crash.
Where the rodlike body of the members consists of a hollow tubular member and the deformable portion described above is a recessed curved wall portion of the hollow tubular member locally formed in a longitudinally intermediate portion of the rodlike body, an axial compressive load buckles the rodlike body of the member in the recessed portion, in the same way as in the above-described case. Thus buckling reduces the impact in a collision. Furthermore, the member for use with the arm is made lightweight, because the rodlike body is a hollow tubular member.
Where the hollow tubular member is of circular cross section, dead space is unlikely to be produced. This enhances the space factor.
Where the hollow tubular member is fabricated by extrusion, the rodlike body of the member can be fabricated efficiently and economically.
Where the aforementioned deformable portion is an axially offset portion locally formed in a longitudinally intermediate portion of the rodlike body of the member, an axial compressive load buckles the rodlike body of the member in the axially offset portion, in the same way as the foregoing. This buckling mitigates the impact in a crash.
The aforementioned crushed wall portion, the recessed portion of the curved wall of the hollow tubular member, and the axially offset portion are formed by plastic working processes such as press working, electromagnetic forming, and spinning, since plastic working processes can form such parts in such a way that the horizontal cross-sectional area is little reduced. That is, a plastic working process has the advantage that it can reduce buckling load while minimizing the decrease in the tensile strength in the body of the member for use with an arm.
Where the deformable portion described above is a thin-walled portion locally formed in a longitudinally intermediate portion of the body of the member, an axial compressive load buckles the body of the member for use with the arm in the thin-walled portion in the same way as the foregoing. This buckling mitigates the impact in a crash.
The thin-walled portion is formed by a cutting operation for the following reason. Indeed, the thin-walled portion may be formed in the body of the member by press working. A press working process can reduce buckling load while reducing the decrease in the tensile strength to a minimum as mentioned previously. However, residual stress causes springback and so it is difficult to obtain high dimensional accuracy where a cutting process is used, no springback is induced and so high dimensional accuracy can be derived. Accordingly, it is desired to form the thin-walled portion by a cutting operation, becaue high dimensional accuracy can be obtained. Examples of cutting processes include cutting operations using a cutting tool, such as turning, planing, and milling, and abrasive-machining processes using abrasive grains such as bonded abrasives and loose abrasives.
The thin-walled portion described above may be formed over the whole circumference or in a part of the body of the member in a circumferential direction. In the latter case, the direction of deformation of the body of the member can be set.
Each of the joints can consist of a bushing-mounting portion having a bushing-holding hole in which a bushing is fitly held. The deformable portion described above can be formed near the bushing-holding hole via a partition wall. The bushing fitted in the bushing-holding hole can be a space to permit the bushing to move the partition wall while plastically deforming it. In this case, an axial compressive load moves the bushing into the space while plastically deforming the partition wall. The resulting plastic deformation of the partition wall mitigates the impact in a crash.
Where the partition wall is made thinner than the other part of the curved wall around the bushing-holding hole, the partition wall easily deforms plastically. This assures that impact is mitigated in a collision.
Where a thin-walled portion is formed in a part of the partition wall, the partition wall easily deforms plastically in the same way. This assures mitigation of impact in a crash.
Where the body of the member is made of aluminum or an aluminum alloy, a lightweight member for use with an arm is obtained. Similarly, where the joints are made of aluminum or an aluminum alloy, a lightweight member for use with an arm can be derived.
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patent: 6298121 (1994
Enomoto Masatoshi
Iwameji Noriyuki
Kato Rentaro
Kawata Naoyuki
Nishikawa Naoki
Butler Douglas C.
Showa Denko K.K.
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