Patent Application
20090095114
The present invention relates to a steering column assembly, and more specifically to a steering column assembly having a rotating drive cable device.
Known drive cable devices typically consist of a flexible sheath and a drive cable. The sheath is designed to support the drive cable with both the sheath and the cable being flexible to allow routing in non-linear geometries. The flexibility of the sheath, or bending stiffness, depends on the amount of cable flexure required to allow routing in the non-linear geometry and the ability to resist normal forces of the cable as torques is applied. This type of drive cable device configuration induces high forces into the drive and driven members and allows significant energy to be stored in the drive cable device. Unfortunately, when the applied torque to the cable is reversed, the stored energy in the cable is released and thus induces a “clunk” into the system. Because such cable devices store energy, they create unwanted noise into the applied assembly.
Typically, the rotating rotor of the electric motor attaches directly to the mechanism it generally automates or drives. Such rigid connections limit placement of the motor in the column assembly and may require complicated and expensive couplings such as worm gears. In general terms, the versatility in the packaging of a steering column is limited and often requires numerous and a variety of parts that contribute toward expensive manufacturing costs. Unfortunately, a degree of motion is lost when a torque is applied to known rotating and sheathed cables making such cables less than ideal for the applications described above.
A rotating cable device preferably for use in a steering column assembly couples a drive member to a driven member of the assembly for rotation and without any lost motion or release of unwanted absorbed energy, which could potentially create inefficiencies in operation and undesirable noise. A rigid sheath of the device extends along a non-linear centerline and a resilient tube preferably extends through the sheath. A flexible cable of the device extends through the tube and couples between the members for rotation. The cable device enables versatility in the arrangement and orientation of the drive and driven members in a variety of different steering column and transmission shift mount applications for vehicles.
Preferably, the drive member is an electric motor and the rotor of the motor couples directly to the cable of the cable device. Use of the device increase versatility in the placement of the motor and reduces or eliminates the need for rigid connections and complicated and expensive couplings such as worm gears. In general terms, the versatility in the packaging of a steering column is enhanced and the variety of necessary parts is reduced. Operation of the steering column assembly is improved and unwanted noise during operation is reduced.
Other objects, features and advantages of the present invention include a steering column assembly that is compact, robust, simple and inexpensive to manufacture, and requires little or no maintenance and in service has a long and useful life.
Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
Referring to
The cable 26 is preferably made of steel having spun strands for providing strength and flexibility. A mid portion 46 of the cable 26 is axially aligned or centered to the tube 28 and has a longitudinal length that is slightly longer than a longitudinal length of the tube 28. Because the cable 26 rotates with respect to the tube 28, the mid portion 46 of the tube 28 is fitted loosely through the tube 28. To enhance flexibility and reduce rotational friction between the tube 28 and the cable 26, the mid portion 46 is substantially cylindrical and opposes a cylindrical inner surface 48 of the tube 28. As best shown in
The tube 28 is preferably made of a resilient and flexible rubber-like material for in-part reducing system noise or clunking of the cable 26. For ease of assembly, the tube 28 loosely fits through the sheath 30 so that a cylindrical outer surface 52 of the tube 28 opposes a cylindrical inner face 54 of the sheath 30. Preferably, the outer surface 52 and the inner face 54 radially define an annular cavity 56 for press fitting of opposite end connectors 58, 60 of the device 20 therein.
The end connectors 58, 60 are preferably made of injection molded plastic and function to snap fit the device 20 to the respective drive and driven members 22, 24 while generally stabilizing the cable 26 for smooth rotational operation. Each connector 58, 60 preferably has an annular base 62, a tubular sleeve 64 projecting axially inward from the base 62, a tubular collar 66 projecting axially outward from the base 62 and a snap fit fastener or cage 68 for engagement to the respective drive and driven members 22, 24.
During assembly of the device 20, the end segments 38, 40 of the tube 28 are abutted axially against the annular bases 62 of the respective connectors 58, 60. The resiliency of the tube 28 exerts a force, directed radially outward, against the sleeves 64 for a tight fit. Because the sleeves 64 are axially longer than the respective end segments 38, 40 of the tube 28, a distal portion of the sleeves 64 is located in the cavity 56 and fitted snugly and radially between the inner face 54 of the sheath 30 at the end sections 42, 44 and the outer surface 52 of the tube 28. One skilled in the art would now know that the end sections 42, 44 of the sheath 30 may be flared radially outward to assist in the fitted axial receipt of the sleeves 64. Moreover, if the end sections 42, 44 are flared, the annular cavity 56 may only be present or defined at the end sections 42, 44, and the remaining longitudinal length or mid portion of the sheath 30 may be in close contact generally with the mid portion of the tube 28.
With end segments 38, 40 of the tube 28 inserted fully into the sleeves 64, a bushing 70 of each connector 58, 60 slides axially over the end portions 34, 36 of the cable 26 and until the bushings 70 abut the bases 62 of the respective connectors 58, 60. When the bushings 70 are abutted or fully installed, they are axially aligned to and located radially inward from the collars 66 of the respective connectors 58, 60. Preferably, the bushings 70 tightly fit to the mid portion 46 of the cable 26 for maintaining axial alignment of the cable 26 with respect to the tube 28 of the sheath 30. As best shown in
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While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.
