Electricity: circuit makers and breakers – Special application – Steering wheel – shaft or column mounted
Patent
1991-09-19
1993-03-23
Scott, J. R.
Electricity: circuit makers and breakers
Special application
Steering wheel, shaft or column mounted
H01H 900, H01H 2150, B60Q 142
Patent
active
051966620
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an electric switch comprising a switching member rotatably located in a housing between several switching positions. The invention is particularly directed to a steering column switch for motor vehicles.
In electric switches the switching positions of a switching member, particularly if the switching member has more than two switching positions, are largely determined by a switch cam and a locking cam lying on the switch cam. Usually the switch cam is fixed to the housing, whereas the locking cam is guided in a receiver of the switching member and is resiliently supported on the switching member. By means of such locking systems it is difficult to perform switching function without noise and without play in the switching positions of the switching member, because noises are immediately transferred to the switch housing and the locking cam in the switching member is guided with play.
Therefore locking systems with locking levers swivelably located in the housing against the force of resilient means are known and have been used in the art. The switch cam or the locking cam is arranged on the locking lever, the counter-part is in a stationary manner formed onto the switching member. The locking lever can be located in the housing to a large extent without play. This particularly can be achieved, if it comprises a film hinge connecting a swivelable section of the locking lever with the fastening section and producing a swiveling axis of the locking lever. In a locking system with a locking lever of the type described above, switching with less noise results.
From German patent document DE-PS 32 11 672 an electric switch is known in which the switch cam is on the switching member and the locking cam is in the locking lever. In this electric switch it is a disadvantage in that for the switching member in the area of the switch cam, substantial space is needed in the switching housing, which space is not always available.
An electric switch with the features according to which the switch cam is on the locking lever and the locking cam is on the switching member is shown in German patent document DE-OS 36 03 820. As to the switch of the type described herein a certain point of the back of the locking lever is supported on a leaf spring fixed to the housing. As to such an electric switch only minimal space on the switching member is needed for the locking cam. However, it is known from experience that the switching characteristics of the locking system change especially under the influence of elevated ambient temperature. Furthermore different switching moments may be experienced between the different switching positions.
It is therefore an object of the present invention to improve the locking system of an electric switch of the general type described herein.
SUMMARY OF THE INVENTION
According to the invention this object is achieved by means of an electric switch comprising the features described herein and in which, in addition, the resilient means can be moved along the locking lever together with the locking cam upon switching the switching member. Thus in an electric switch of this type upon switching, both the locking cam and the resilient means are moved in relation to the locking lever and the switching moments between the different switching positions are adapted to each other in a convenient manner.
It is advantageous if the resilient means act upon the locking lever at least approximately at the same distance as the distance of the locking cam from the swiveling axis of the locking lever. Thus it is achieved that in the different switching positions the different lengths of the levers no longer affect the switching moments. Since the locking lever is supported just at the point the locking cam presses onto it, the locking cam no longer bends the locking lever so that the locking lever keeps its form even under the influence of elevated temperature and the switching characteristics of the locking system remain the same.
In a preferred embod
REFERENCES:
patent: 4328431 (1982-05-01), Usami
patent: 4414442 (1983-11-01), Berginski et al.
patent: 4791253 (1988-12-01), Erdelitsch et al.
patent: 4882457 (1989-11-01), Erdelitsch et al.
Lewis J. Gordon
Scott J. R.
Seitter Robert P.
SWF Auto-Electric GmbH
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