Electrical rotary switch

Details Electrical rotary switch Electrical rotary switch

1999-08-17

2001-01-30

Friedhofer, Michael (Department: 2832)

Electricity: circuit makers and breakers

Electric switch details

Contact

C200S0110TC

Reexamination Certificate

active

06180901

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to an electrical rotary switch for several switch positions having a control knob mounted in a housing supported on one side, or on two sides, by three ball bearings that, guided by a cage disk, roll in a housing groove formed by an axial wall and a radial wall against which the ball bearings are loaded under the pressure of an outer or inner conical bearing surface of the control knob, whereby the axial—and radial-wall bearing surfaces respectively have contact segments and contact bands thereon that extend out of the housing via terminal lugs and are shorted by a first of the ball bearings in predetermined switch positions.
German patent document (DE 197 20 544. 4), for example, which has not previously been published, discloses a rotary switch of this type having circularly-arranged contacts in a base unit.
This rotary switch provides a compact structure with sensitive adjustment, having a sufficiently large adjustment range of the control knob, which is based on the principle that a ball or roller on which an object rolls, rolls at half the speed of the object, and travels only half the distance. In the described embodiment of a rotary switch, a step down is achieved from the actuating movement of the control knob to displacement of ball bearings, and to displacement of a cage guiding the ball bearings, without, for example, requiring toothed gearing. Since ball bearings have only one point of contact to their supports, current flowing through the ball bearings is limited. There arises, therefore, a need, in order to achieve given sensitive adjustments, to also be able to switch-in greater currents, particularly in a last position of a step switch.
Accordingly, it is an object of the invention to provide a rotary switch of the type set forth in the opening paragraph above which has a sensitive adjustment and an increased switching current.
SUMMARY OF THE INVENTION
According to principles of this invention, in a last switch position of a rotary switch of the type set forth in the opening paragraph above, contact occurs between a second contact segment and second and third contact bands through second and third ball bearings. In one embodiment contact between a first contact segment and a first contact band is also maintained by the first ball bearing in the last switch position. In one embodiment the second contact segment has indexing positions corresponding to switch positions of one of the second and third ball bearings, the indexing positions being formed by recesses in the second contact segment into which the ball bearing engages. In another embodiment the first contact segment has recesses corresponding to the switch positions of the first ball bearing. In one embodiment a conical bearing surface of the control knob has recesses, corresponding to indexing positions in which at least one of the first, second and third ball bearings engages. It is a feature of the rotary switch of this invention that, in the last switching position, contacting occurs between the second contact segment and the second and third contact bands through the second and third ball bearings positioned on one or on two sides of the second contact segment. A high current load of the rotary switch is achieved in this manner.


REFERENCES:
patent: 3534194 (1970-10-01), Speller
patent: 4742187 (1988-05-01), Sorenson
patent: 5204502 (1993-04-01), Ferris et al.
patent: 5227595 (1993-07-01), Sorenson et al.
patent: 5959269 (1999-09-01), Bauer et al.
patent: 1 921 801 (1970-11-01), None
patent: 25 05 760 C3 (1978-05-01), None
patent: 82 11 566 U (1982-08-01), None
patent: 197 20 544 C1 (1998-04-01), None

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