BUSHING ASSEMBLY FOR REDUCING BACKLASH

RELATED APPLICATION

[0001] This application claims the benefit of U.S. Patent Application No. 1 1/582,614, filed October 17, 2006, which is hereby incorporated by reference in its entirety.

BACKGROUND

Technical Field

[0002] The present invention relates generally to a bushing assembly, and more particularly, to a bushing assembly that reduces backlash.

Background

[0003] In many applications, especially in positioning devices such as fine adjustment actuators, it is desirable to have a screw and a matched bushing that can reduce or eliminate backlash. Many anti-backlash mechanisms have been proposed, for example, using materials that may have a long wear life time to make the screw and the bushing, or using washers, or using other mechanisms. However, using long wearing materials may increase the manufacturing cost of the screw and the bushing, and using washers may degrade the accuracy for fine positioning devices. Other conventional anti-backlash devices and methods also fail to provide satisfactory results. Therefore, there is a need for a bushing that can effectively reduce or eliminate backlash, satisfy accuracy requirements, and be inexpensively manufactured.

Summary of the Invention

[0004] According to some embodiments, the present invention is directed to a bushing for reducing backlash. The bushing may include a bushing body extending along a central axis. The bushing body may have a central bore extending along the central axis, and may include a first section, a second section, and a resilient section coupled between the first section and the second section.

[0005] According to some other embodiments, the bushing may include a bushing body extending along a central axis. The bushing body may have an annular wall and a central bore within the annular wall. The central bore may extend along the central axis, and

may include an inner circumferential surface having a thread thereon. The bushing body may include a first section, a second section, and an intermediate section between the first section and the second section. The annular wall of the intermediate section may include a spiral shape structure formed by partially removing the annular wall of the intermediate section. [0006] According to some embodiments, the present invention is directed to a bushing assembly for reducing backlash. The bushing assembly may include a first section, a second section, and a resilient section coupled between the first section and the second section.

Brief Description of the Drawings

[0007) FIG. 1 is a perspective view of an exemplary disclosed bushing according to some embodiments of the invention;

[0008] FIG. 2 is a cross-sectional view of an exemplary disclosed bushing according to some embodiments of the invention; and

[0009] FIG. 3 is a perspective view of an exemplary disclosed bushing assembly according to some embodiments of the invention.

Detailed Description

[0010] FIG. 1 illustrates a perspective view of an exemplary bushing 10 according to some embodiments of the present invention. The bushing 10 may include a cylindrical body 12 extending along a central axis A between a first end 14 and a second end 16. FIG. 2 illustrates a cross-sectional view of the bushing 10. As shown in FIG. 2, the bushing body 12 may have an annular wall 18 and a central bore 20 within the annular wall 18. The central bore 20 extends along the central axis A. The central bore 20 may include an inner circumferential surface 22 having a thread formed thereon. The central bore 20 is adapted to receive a screw member (not shown) which may have an outer circumferential surface having a thread that is adapted to engage the thread formed on the inner circumferential surface 22 of the bushing 10.

[0011] As shown in FIGS. 1 and 2, the bushing 10 may include a first section 32, a second section 34, and an intermediate section 36 between the first section 32 and the second section 34. The intermediate section 36 may include a resilient section. In some embodiments, the first, second, and the intermediate sections 32, 34, and 36 are integrally formed, and the intermediate section 36 may be a spiral spring formed by having the annular

wall 18 partially removed, leaving a spiral spring shape structure coupled between the first section 32 and the second section 34. The bushing 10 may be made from a resilient material, for example, a metal. Thus, the spiral spring shape structure 36 may be resilient and function like a spring. As shown in FIG. 2, in some embodiments, the central bore 20 passes through the first section 32 and the second section 34. In use, a leading end of a screw can pass through the first section 32, and can extend into the second section 34. During securing the leading end of the screw in the second section 34, the resilient section 36 may be compressed by the first section 32 and the second section 34. The compressed resilient section 36 may provide a constant preload pressure to the threaded screw, and thus may reduce the backlash of the screw inserted therein.

[0012] FIG. 2 shows that the central bore 20 passing through the second section 34 of the bushing 10, and the entire inner circumferential surface within the first section 32 and the second section 34 has a thread formed thereon. However, a person skilled in the art should appreciate that the second section 34 may have a central bore that extends into part of the second section 34, and may have a thread on part of the inner circumferential surface. [0013] In some embodiments, the spiral spring shape structure 36 is formed by removing part of the bushing body 12, for example, by cutting away part of the annular wall 18 of the bushing body 12. In some other embodiments, the bushing 10 may employ other a resilient section coupled between the first section 32 and the second section 34. For example, the bushing 10 may have a spring being coupled between the first section 32 and the second section 34.

[0014] FIG. 3 shows another embodiment of the invention. As shown in FIG. 3, a bushing assembly 100 may include a first section 132, a second section 134, and a resilient section 136 between the first section 132 and the second section 134. The first section 132 may be a nut or a washer. The second section 134 may be a nut or a washer. The resilient section 136 may be a spring coupled between the first section 132 and the second section 134.

[0015] It will be apparent to those skilled in the art that various modifications and variations can be made to the bushing for reducing backlash. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed bushing for reducing backlash. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.