Electrical transmission or interconnection systems – Plural load circuit systems – Transformer connections
Utility Patent
1999-03-31
2001-01-02
Paladini, Albert W. (Department: 2836)
Electrical transmission or interconnection systems
Plural load circuit systems
Transformer connections
C280S735000, C336SDIG002, C439S950000
Utility Patent
active
06169339
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rotating signal transducer for electronic signal communication In a steering column of a vehicle.
BACKGROUND
Since the advent of steering-wheel mounted air bags, the necessity of transmitting multiple electric signals between the steering wheel and the column has resulted in a series of devices generically referred to as ‘clock springs’, comprised of a spiral tape of multiple conductors laminated within a plastic strip, wound within a housing, through which electrical connection is made between the wheel and column circuits. As the steering wheel is turned, this tape winds and unwinds while maintaining electrical contact.
Because of the finite length of the tape, there is a limited number of turns through which the clockspring may be exercised before reaching the limit of its travel. Because of this, particular care must be taken during installation of the clockspring into the vehicle so that both the steering linkage of the vehicle and the clockspring tape are centered so that when the steering wheel is turned, the clockspring does not reach its limit before the steering system reaches its end-stops. Additionally, there is some acoustic noise associated with the motion of the tape within the housing which may be objectionable in certain applications.
The present invention relates to an connector transmission system for signal, data, and power which provides signal coupling for data transfer between a stationary housing and a rotatable hub, and in particular to efficient data transfer and signal coupling which allows for the unlimited rotation of the hub with respect to the housing.
Rotary signal transducers, or clocksprings, are used for connecting automotive steering wheel mounted electronic circuits, including switches, lights, and an airbag squib, to other sensing and control electronic circuits mounted in various other locations of the automobile.
For example, U.S. Pat. No. 5,061,195 (1991), issued to Bolen, discloses a transducer, described as a clockspring, which provides a direct electrical connection between relatively movable members in the steering apparatus of an automobile. In this type of clockspring construction, a ribbon cable is used to provide the electrical connection between the relatively movable members. The ribbon cable is constructed of conductive material which is sandwiched between two layers of mylar. The cable is loosely accommodated in a coiled state within the clockspring's housing. In addition, one end of the cable is attached to the clockspring's stationary housing and the other end of the cable is attached to the clockspring's rotatable hub.
In operation, the ribbon cable will wrap or unwrap around the hub when the hub is rotated. However, in order to prevent the cable from being damaged during rotation of the hub, no substantial tensile force can be applied to the ribbon cable while it is wrapping or unwrapping. Thus, the length of the cable determines how many times the hub can be rotated. If the hub is rotated too far in one direction, then an overwound condition is said to occur which results in a significant amount of damaging tensile force being applied to the cable.
In order to prevent excess tensile force from being applied to the cable, it is necessary for the hub to be centered when it is mounted on the steering apparatus. Centering of the hub allows for the same extent of clockwise and counterclockwise rotation of the hub before the ribbon cable becomes overwound.
If the hub is not in the centered position when the clockspring is mounted on the steering apparatus, then the cable will be damaged when it is completely wrapped and/or unwrapped around the hub while the steering apparatus is continued to be forced to turn.
To ensure that the clockspring is centered when it is mounted on the steering apparatus, external locking mechanisms are sometimes used such as those described in U.S. Ser. No. 08/285,021. These locks allow only limited rotational travel of the hub prior to the clockspring's installation. The external lock is disengaged by removing it from the clockspring and discarding it.
Likewise, internal locking mechanisms are also sometimes used in order to prevent rotation of the hub such as U.S. Pat. No. 5,171,157 (1992), issued to Bolen. An internal lock limits the travel of the hub whenever the clockspring is not mounted to the steering apparatus. The internal lock is usually disengaged by a pin or other unlocking system which is provided by the steering apparatus. The clockspring's lock will reengage whenever the clockspring is removed from the steering apparatus.
However, if the clockspring is removed from the steering apparatus and then subsequently reinstalled, both the external lock and the internal lock will fail to ensure and/or indicate when the transducers hub is properly centered.
Many devices have been proposed which provide a way of indicating if the clockspring's hub is centered. However, these devices cause an increase in the diametrical size of the transducer and/or require the use of gears or other mechanisms which have a very limited useful life due to their constant rotating or relative motion whenever the hub rotates.
In addition to the centering problems posed by the prior art clocksprings, the ribbon cable used in the clockspring produces unwanted noise due to vibration, impact, and its sliding during winding and unwinding.
Also the small cross sectional area and long length of the conductors within the multi-conductor ribbon cable pose significant limitations on electrical current flow due to voltage drop and self heating.
Additionally, sliding contacts are known in the field of rotary signal transducers, but are electrical noisy and are not sufficiently reliable for data communication transfer without error checking techniques which slow down data transfer.
Another rotating signal transducer or clockspring is provided by Ballast, et al., as U.S. Pat. No. 5810606, issued Sep. 22, 1998 and titled “Connector Transmission System For Signal Data And Power.” Ballast shows an connector assembly having a housing, a hub being carried in rotatable relation to the housing; and means for signal coupling between the housing and the hub. The signal coupling can consist of means such as optical coupling, inductive coupling, radio frequency coupling, capacitative coupling, and pressure wave coupling. In addition, the connector assembly can further include power coupling which can be accomplished by sliding contacts, inductively coupled coils, capacitatively coupled electrodes, or optical transmitters and receivers on the hub and the housing. Furthermore, a method of efficiently transmitting and receiving signals between the housing and hub is provided. The method consists of (1) obtaining an input signal, by a signal driver, to produce a driven signal output; (2) coupling the driven signal output to produce a coupled signal; and (3) receiving the coupled signal, by a receiver, to produce an output signal. In addition, the method can further include decoding and encoding, respectively, of the output and input signals.
Therefore, a device is proposed which provides signal coupling between the rotating hub and stationary housing of an connector transmission assembly. This device thereby eliminates the need to center the hub and housing members and also removes unwanted audible noise associated with the conductive tape in a clockspring.
In view of the above, it is an object of the present invention to provide a hub and a housing which does not require centering.
A further object of the invention to eliminated the possibility of an overwound condition.
Still further, another object of the present invention is to provide an efficient data transfer method between the hub and the housing of an connector transmission assembly.
Another object of the present invention is to provide an efficient signal, data, and power transfer method between the hub and the housing of an connector transmission assembly, which with accompanying energy storage and suit
Evans Steven M.
Methode Electronics Inc.
Newman David L.
Paladini Albert W.
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