Electricity: circuit makers and breakers – Electric switch details – Actuators
Reexamination Certificate
2003-10-03
2004-06-08
Friedhofer, Michael A. (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Actuators
C200S520000, C200S523000, C200S528000, C337S068000
Reexamination Certificate
active
06747225
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a switch that cuts the circuit by using a bimetallic plate when overload and no fuse or breaker is required.
BACKGROUND OF THE INVENTION
A conventional switch known to applicant is disclosed in
FIGS. 1 and 2
and generally includes a base
1
with two terminals
7
and a conductive plate
27
. The two terminals
7
each have a first contact point
9
and the conductive plate
27
has two second contact points
271
which are lowered to contact the first contact points
9
by pushing a button assembly
25
. A first spring
11
is biased between the inside of the base
1
and the conductive plate
27
and a second spring
23
is biased between the button assembly
25
and the conductive plate
27
, wherein the first spring
11
has a larger spring force than the second spring
23
so that the conductive plate
27
is located at a position as shown in FIG.
1
. When pushing the button
252
of the button assembly
25
, the conductive plate
27
is lowered and the second contact points
271
contact the first contact points
9
as shown in FIG.
2
. The conductive plate
27
is raised by the first spring
11
when the button
252
is pushed again and released by the operation of the mechanism of the button assembly
25
. This switch cannot respond when the current overflows so that many safety switches are developed, such as U.S. Pat. Nos. 5,786,742, 5,223,813, 4,937,548, 4,661,667, 5,223,813, 4,931,762, 5,451,729, and 4,704,594. A common shortcoming of the safety switches is that there is a complicated mechanism involved in each base and most of them is suffered by a problem of delay response.
Therefore, it is desired to have a safety switch that requires only a simple structure which responses the current overflow so as to cut off the circuit.
SUMMARY OF THE INVENTION
In accordance with an aspect of the present invention, there is provided a safety switch that comprises a base having two terminals and each terminal has a first contact point. A bimetallic plate is movably received in the base and two second contact points are connected to two ends of the bimetallic plate. The two second contact points are located above the two first contact points and the two ends of the bimetallic plate can be bent when overflow. A first spring is biased between an inside of the base and the bimetallic plate. A button assembly is connected to the base and a second spring is biased between the button assembly and the bimetallic plate. The two second contact points on the metallic plate are removed from the first contact points when the metallic plate is bent.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.
REFERENCES:
patent: 3686601 (1972-08-01), Kaczmarek et al.
patent: 4682138 (1987-07-01), Sell
patent: 6377159 (2002-04-01), Yu
patent: 6552643 (2003-04-01), Chen
patent: 6621028 (2003-09-01), Bartok
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