Automobile Clockspring With Vibration Dampener

This invention pertains to a clockspring interconnector for enclosing an electrical conductor cable, the clockspring interconnector electrically connecting a rotatable electric device with a stationary electric device.

An increasing number of automobiles have air bag crash systems. An air bag is typically located on the steering wheel facing the driver. The air bag must be in continuous electrical connection with sensors in the car body. The sensors provide an electrical signal to the air bag crash assembly which instantly inflates the air bag in the event of a crash.

Accordingly, there is a need for an electrical connection between the rotatable portion of the air bag assembly which is mounted to the steering wheel, and the remaining portion of the assembly, which is in a stationary position in the car body. Electrical connections between rotatable and stationary parts are well known. Typically, an electrical brush rests upon a conductive ring, with one of the parts being rotatable to provide such rotatable electrical connection. However, there is a risk, particularly during the impact of an accident, of a transient failure of electrical connection with a brush and ring system, which would result in failure of the entire air bag system crash assembly.

Accordingly, a clockspring interconnector has been previously developed, comprising an outer housing, a rotor member and multiple intermediate housing members for enclosing and connecting the members; the housing and rotor member rotatably associated with one another at a plurality of bearing surfaces. A "clockspring" is located inside the interconnector. The clockspring is a flat conductor cable and has two ends conductively attached to conductor wires which pass out of the interconnector to unite the air bag to the sensing device. The interconnector is mounted on the steering column, and the steering wheel may be rotated in either direction while a continuous, positive electrical connection is provided between air bag sensors via the clockspring interconnector.

While prior art clockspring interconnectors are effective to provide the necessary continuous electrical connection between an air bag or other device on a rotating column and a stationary portion of a circuit, the prior an systems do not provide for proper reduction of noise which occurs due to vibration of the flat cable within the clockspring housing. It is known in the prior an to include insulation materials within a clockspring housing in order to deaden the sound created by the scraping of the flat cable during rotation of the clockspring. However, there is additional noise created while the clockspring is stationary due to vibrations caused by the movement of the automobile. The vertical vibration of a steering column causes the flat cable of a clockspring to vibrate and rattle against the adjacent coils of the flat cable. Accordingly, there is desired a clockspring which includes a vibration dampener to avoid the above disadvantages.

It has been disclosed in U.S. Pat. No. 4,925,122 to have presser members which are secured to the wails of the housing of a clockspring and provide pressure against the flat cable. This invention is disadvantageous in that the presser members are complicated to install within a clockspring and are expensive to manufacture. The presser members also provide only minimal points of contact to compress the flat cable. Thus, there is needed a vibration dampener which is quickly and easily installed and is inexpensive to manufacture. Also, a vibration dampener which provides multiple points of contact to a flat cable for compression would be advantageous.

It is an object of the present invention to provide a clockspring assembly including a vibration dampener to greatly reduce the vibration of the flat cable of a clockspring.

It is another object of the present invention to provide a clockspring assembly, including a sound dampener which is easily incorporated into a clockspring assembly and is inexpensive to manufacture.

The above objects and advantages are provided by a clockspring interconnector comprising a housing defining a chamber extending therethrough and a rotor cover attached to the housing. A coiled flat cable carried within the chamber surrounding the rotor cover. The flat cable having a first end attached to a first connector location of the rotor cover and a second end attached to a second connector location of the housing.

The chamber includes a vibration dampener preformed to expand upon unwinding of the flat cable and to compress upon winding of the flat cable. An outer vibration dampener having preformed bends is located between the flat cable and an exterior housing wall. An inner vibration dampener having preformed bends is located between the flat cable and an internal rotor hub. The inner vibration dampener is attached to the inner rotor hub.

These and other features of the invention are set forth below in the following detailed description of the presently preferred embodiments.

FIG. 1 is a top view of a prior art clockspring;

FIG. 2 is a side elevation view of a prior art clockspring;

FIG. 3 is a top view of a clockspring; and

FIG. 4 is a top view of a further embodiment of a clockspring.

The clockspring interconnector of this invention is better understood by reference to FIGS. 1-4. FIG. 1 shows a clockspring 10 having a housing wall 12 and a rotor hub 14. The housing 12 generally has a cover which has been removed from this drawing so that the inside of the clockspring 10 may be viewed. A chamber 16 is defined between the housing wall 12 and the rotor wall 14. A flat conductor cable 18 is wound within the chamber 16. The flat cable 18 is connected to the nonmovable housing 12 at point 20 and at the opposite end of the flat cable 18 it is connected to the movable rotor 14 at point 22. When the clockspring 10 is assembled with a steering assembly the housing 12 is stationary and attached to the steering column while the rotor hub 14 is attached to and rotates with the steering wheel.

It can be seen that the flat cable 18 is loosely wound within the chamber 16. This figure depicts the clockspring in its centered position. The clockspring may be turned clockwise which will wind flat cable tighter. The clockspring 20 may also be turned counter-clockwise which will unwind the flat cable and make it even looser. It can be seen that there are no objects within the chamber 16 to obstruct the movement of the flat cable 18. Upon installation on a steering column in an automobile, vibrations occur which cause the flat cable to vibrate against the housing 12 and also against the adjacent flat cable coils. This vibration causes noise which is unsatisfactory. The prior art clocksprings in their centered position and their unwound position allow for the flat cable to be loosely wound which causes vibration and unacceptable noise levels.

FIG. 2 is a side elevation view of FIG. 1 taken at line 2--2. This view shows the housing 12 and rotor 14 defining chamber 16 in which the flat cable 18 is shown. It can be seen that the flat cable is loosely wound having space between the coils. This loosely wound flat cable 18 vibrates uninhibited and provides unsatisfactory noise levels when the clockspring is installed on a steering column.

FIG. 3 shows a preferred embodiment of the present invention having a clockspring housing 30 and rotor hub 32 defining chamber 34. Within the chamber 34 is flat conductor cable 36. The flat cable 36 is attached to the housing 30 at point 38 and its opposite end attached to the rotor hub 32 at point 40. Vibration dampeners 42,44 are provided to compress the flat cable 36 in order to limit vibration. In a preferred embodiment, inner vibration dampener 44 is inserted around the rotor hub 32 and outer vibration dampener 42 is inserted against the housing wall 30. The vibration dampener 42,44 may be constructed of an elastic polyester material and preformed to include folds 46. In a preferred embodiment, the outer vibration dampener 42 is mylar and has five folds 46. The inner vibration dampener 44 may be made of a similar polyester material with preformed folds. The inner vibration dampener 44 may be attached to the rotor hub 32 at point 40. The attachment may occur by any means and may be attached similar to the attachment means of the flat cable 36 at point 40.

The vibration dampener 42,44 provides fix the dampening of the vibrations caused by the flat cable 36 by compressing the flat cable together. FIG. 3 depicts a clockspring 18 in the centered position similar to the clockspring 10 shown in FIG. 1. The clockspring 18 may be wound clockwise which will cause the flat cable 36 to wind tighter; or the clockspring 18 may be turned in a counter-clockwise direction which will cause the flat cable 36 to unwind and loosen. It can be seen that the flat cable 36 of clockspring 18 shown in FIG. 3 is compressed so that the spacing between the coils of the flat cable 36 is small. This is unlike the clockspring 10 depicted in FIGS. 1 and 2 in which the clockspring was also in the centered position but the flat cable 18 was loose. The use of the vibration dampeners 42,44 having preformed folds 46 cause the vibration dampeners 42,44 to abut against the flat cable 36.

The outer vibration dampener 42 by maintaining its folds 46 causes abutment points 48 midway between the folds to make contact with the flat cable 36 and compress it inwardly toward the rotor hub 32. The inner vibration dampener 44 maintains its folded shape and causes fold points 50 to abut against the flat cable 36 and push the flat cable outwardly toward the housing wall 30. The joint action of the inner vibration dampener 50 pushing outward and the outer vibration dampener 42 pushing inward, forces the coils of the flat cable 36 to be closely spaced which reduces the amount of vibration between the coils of the flat cable 36 and against the housing 30.

FIG. 4 shows the clockspring 18 in a totally unwound position wherein the clockspring has been turned counter-clockwise from its position in FIG. 3. This depiction shows that upon rotation of the clockspring in a counter-clockwise direction, the flat cable 36 unwinds and pushes outwardly. The outer vibration dampener 42 is of a flexible material which allows it to expand outwardly with the flat cable 36. Thus, the vibration dampeners 42,44 do not inhibit the movement of the flat cable 36 upon rotation of the clockspring 88. As the clockspring 18 is turned back, clockwise to its centered position, the outer vibration dampener 42 will retain its folded position as shown in FIG. 3.

In a preferred embodiment, both the inner vibration dampener 44 and the outer vibration dampener 42 are used, within the clockspring 18. However, this invention also anticipates that only the outer vibration dampener 42 may be used or that only the inner vibration dampener 44 may be used to provide a reduction of the noise level caused from the vibration of the flat cable 36. The vibration dampeners 42,44 of this invention may also be used in combination with an insulation layer 52 attached to the top and bottom inner surfaces of clockspring 18. The vibration dampeners 42,44 may be easily assembled within the housing 30 of the clockspring 18. Following attachment of the flat cable 36 to the housing 30 at point 38 and the rotor hub 32 at point 40, the vibration dampeners 42,44 may simply be inserted next to the flat cable 36. Upon complete assembly of the clockspring by putting a cover over the housing 30, the vibration dampeners 42,44 will be secured within the chamber 34 of the clockspring 18.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages.. It is, therefore, intended that such changes and modifications be covered by the appended claims.