Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – With bimetallic elements
Reexamination Certificate
2003-05-31
2004-09-07
Vortman, Anatoly (Department: 2835)
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
With bimetallic elements
C337S056000, C337S091000
Reexamination Certificate
active
06788186
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a switch device that includes an activation mechanism for directly activate a bimetallic plate of the switch device. The mechanism includes a driving plate having an aperture with three recesses so as to provide the guide pin a movement path during operation between ON and OFF status.
BACKGROUND OF THE INVENTION
A conventional switch device, especially for those switches using a bimetallic plate to prevent the switch device from being burnt out when an overload happens, is known, such as U.S. Pat. Nos. 4,167,720; 4,937,548; 5,223,813; 5,451,729; and 5,558,211. Nevertheless, the switches commonly involve a complicated structure and are composed of a great number of parts, which leads to high risk of malfunctioning. Besides, activation of the bimetallic plate is indirectly done by a toggle so that the metallic plate is activated for a period of time after the action on the toggle is completed. This very short period of time could result in bum out of the switch device in an overload of the current.
FIGS. 1-3
of the attached drawings show the device disclosed in U.S. Pat. No. 5,223,813, and the switch member is connected to a link that is then connected to an arm. A bimetallic plate is compressed by the arm and is deformed when the arm is activated by the link and the switch member. The direct press on the metallic plate from the arm could break the metallic plate and the reaction of the metallic plate is slower than expected.
Therefore, it is desired to have an activation mechanism for switch devices wherein the metallic plate is not directed pressed by any part in the switch device so as to improve the shortcomings of the conventional switch devices.
SUMMARY OF THE INVENTION
In accordance with an aspect of the present invention, there is provided a casing having a path defined therein and a protrusion is surrounded by the path. Two first terminals extend from a bottom of the casing and one of which has a first contact point.
A push member is movably engaged on a top of the casing and two positioning springs are biased between the push member and the casing. A guide pin is pivotably connected to the push member and includes an insertion that is movably engaged with the path in the casing. A bimetallic plate has an end connected to the other terminal and includes a free section. A second contact point is connected to the free section and located above the first contact point.
A driving plate is rotatably connected to the casing and includes a polygonal aperture including a first recess, a second recess and a third recess. The insertion of the guide pin and the protrusion extend through the aperture. A hook portion extends from the driving plate and holds a free end of the bimetallic plate. The insertion is engaged with the first recess when the switch device is in OFF status. The insertion is engaged with the third recess when the switch device is in ON status. The second recess allows the guide pin in the aperture not to impede the rotation of the driving plate when overload.
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.
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