Electricity: circuit makers and breakers – Special application – Turn indicator type switches
Reexamination Certificate
1997-07-28
2001-08-21
Luebke, Renee (Department: 2833)
Electricity: circuit makers and breakers
Special application
Turn indicator type switches
C200S018000, C200S332000
Reexamination Certificate
active
06278070
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention pertains to a switch for motor vehicles which comprises a pivoted operating lever, one pivoting position of which represents a neutral position that also has an assigned electrical state.
DE-OS 3,249,359 discloses a steering column switch, in which the left or right turn signals are respectively connected to a voltage source via sensitive microswitches if the operating lever is manually moved into the two operating positions. In this particular switch, no circuit is closed in the neutral position of the operating lever.
In this known steering column switch, the sensitive microswitches are realized in the form of encapsulated circuit switches that are actuated by the operating lever.
A similar switch with two sensitive microswitches that are realized in the form of make contact elements and selectively actuated via the operating lever is used as a mode selection switch in construction machines and tractors. In one operating position of the operating lever, the transmission is shifted into the forward mode, with the transmission being shifted into the reverse mode when the operating lever is moved into the other operating position. In such instances, it would be desirable to close an additional circuit in the neutral position of the operating lever which, for example, is looped into the starter circuit of an internal combustion engine.
The additional circuit that is closed in the neutral position of the operating lever should be interrupted in both operating positions of the operating lever so as to effectively prevent the internal combustion from starting in one of the operating positions that represent the forward mode and the reverse mode of the transmission.
DE-OS 3,623,979 discloses a suitable switch for this purpose that fulfills its function with only two sensitive microswitches. However, the switches disclosed in this publication are relatively complicated and have a comparatively large space requirement. In addition, the switching contacts are not well protected, i.e., the switching contacts are easily affected by dirt and corrosion.
A similar switch is described in DE-OS 2,855,451.
An object of the invention consists of designing a switch with three switching positions in such a way that it can be inexpensively manufactured and that it is largely insensitive to environmental influences.
SUMMARY OF THE INVENTION
This objective is attained with-a third encapsulated microswitch that is assigned to the neutral position and delivers the desired signal.
The operating lever must have a sufficient size in order to ensure its simple handling, but the travel range of the microswitches available on the market is very small. According to the invention, the operating lever is made into a T-shape and can be selectively rotationally moved around a pivoting axis passing through the lever in an area of intersection of horizontal and vertical portions of the T-shape. In order to realize a precise switching function of the microswitches, the operating lever does not directly act upon the actuating pin of the corresponding microswitch, but rather indirectly via a terminal link that carries out the suitable power and directional transmission. The operating lever engages on the terminal links of the first and second microswitches by the ends of its horizontal portion and acts on the terminal link of the third microswitch by the free end of its vertical portion, respectively.
Such a terminal link may be arranged on the end of a microswitch such that it can be independently turned. However, this predetermines a power and directional transmission that is considered unsuitable for the actuation of a microswitch in the neutral position because only a relatively small angular movement is frequently available for the actuation of the switch. In order to ensure a precise switching function in this respect, a pivotal axis for the third terminal link is arranged normal to the plane of the base plate and a pivoted end of the third terminal link acts upon an actuating pin of the third microswitch. These features make it possible to realize a relatively low spring constant with respect to the contact between the terminal link and the operating lever, and to actuate the actuating pin of the microswitch with a comparatively short travel of the terminal link.
In order to increase the travel of the operating lever that only passes the actuating pin over a relatively short distance in the actuating direction of the actuating pin, the operating lever is provided with a control projection that engages on the third terminal link and actuates this terminal link during a pivoting motion of the operating lever. These features make it possible to hold the microswitch in the desired actuating state in the small, limited switching positions of the operating lever. This may, in principle, be realized by providing a control contour on the guide projection which acts upon the terminal link and controls the actuating pin via the terminal link.
In order to reduce the friction caused thereby and the resulting wear, a sampling roller is arranged in rotatable fashion on the third terminal link in such a way that the sampling roller samples a control contour arranged on the operating lever control projection during the pivoting motion of the operating lever. Due to these features forces exerted in the longitudinal direction of the terminal link are reduced to a minimum, i.e., the operating lever can be operated very easily.
The microswitches are held between projections that protrude normally from the base plate.
In order to additionally prevent the third microswitch from moving opposite to the installation direction, the microswitch is held on the base plate by a projection latch connection where a latching tab is provided that engages behind a lateral edge of the microswitch.
An additional holding projection engages the third microswitch into a through opening therein.
This additional holding projection may be hot-deformed on the end thereof that protrudes beyond the through opening in such a way that it engages behind an edge of the through opening.
There are provided windows in the base plate, and electrical connections of the microswitches lie above the windows, with connecting lines that lead to the electrical connections extending through the windows from underneath the base plate.
One embodiment of the invention is described below with reference to the figures.
REFERENCES:
patent: 2796499 (1957-06-01), Barden et al.
patent: 2444808 (1976-04-01), None
patent: 3211672 (1983-10-01), None
patent: 3623979 (1988-01-01), None
patent: 2551704 (1985-03-01), None
patent: 2084805 (1982-04-01), None
patent: WO 9608390 (1996-03-01), None
English Translation of the International Preliminary Examination Report of International Appl. No. PCT/EP95/03535.
Klein Rudolf
Neubauer Walter
Prang Josef-Elmar
ITT Manufacturing Enterprises Inc.
Lewis J. Gordon
Luebke Renee
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