The present invention relates to a safety switch that ensures the bimetallic plate to be deformed as desired when overload.
A conventional switch device, especially for those switches using bimetallic plate to prevent from being burn when an overload is happened, generally includes a bimetallic plate which is deformed when overload so as to separate the two contact points respectively located on the bimetallic plate and one of the two terminals. Some inherent shortcomings for these conventional safety switch devices are found. There are too many parts involved in the safety switch device and a longer period of time is required when assembling the switch device, this increases the cost of the products. The parts might be arranged inaccurately and affects the deformation of the bimetallic plate. Once the bimetallic plate is deformed to cut off the circuit, because of the improper arrangement of the parts as mentioned above, the bimetallic plate could deform to re-connect the two contact points to connect the circuit again. Because the inaccuracy of the deformation of the bimetallic plate, the switch member does not set the “OFF” position after the bimetallic plate is deformed to cut off the circuit.
Therefore, it is desired to have a safety device that allows the bimetallic plate to deform toward a desired direction and there is enough space to prevent the bimetallic plate from bouncing back to connect the circuit again.
In accordance with an aspect of the present invention, there is provided a switch device that comprises a body with a switch member pivotably engaged with the top opening of the body. A first terminal and a second terminal extend through a bottom of the body. A contact portion extends from an inside of the body. The switch member has an engaging hole and an extension slot is in communication with the engaging hole. A contact plate is a curve flexible metal plate and has a first end fixed to the first terminal and a first contact point is connected to an underside of a second end of the contact plate. A second contact point is located above the second terminal. The first contact point is located above the second contact point. A link has an upper end pivotably engaged with the engaging hole and a lower end of the link is connected to the second end of the contact plate. At least one biasing plate extends from a side of the link. When the switch device is in “ON” status, the at least one biasing plate is in contact with the contact portion to provide a potential force to allow the upper end of the link to move into the extension slot when overload.
The main object of the present invention is to provide a safety switch that provides a sufficient space for movement of the spring member so that the contact plate is deformed completely to cut off the circuit.
Another object of the present invention is to provide a safety switch wherein the switch member is pivoted to “OFF” position when overload.
Yet another object of the present invention is to provide a safety switch that includes less number of parts so as to have lower manufacturing cost.
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.
Referring to the drawings and in particular
A contact plate 3 is a curve flexible bimetallic plate and has a first end fixed to the first terminal 11 and a second end of the contact plate 3 is a free end. A contact portion 31 splits from the contact plate 3 and a first contact point 311 is connected to an underside of the contact portion 31. A free end of the contact portion 31 is located above a top surface of the contact plate 3 and connected with a free first end of a spring member 32. The free end of the contact portion 31 has a tongue 312 and the free first end of the spring member 32 has a first slot 321 with which the tongue 312 is engaged. The second end of the spring member 32 has a second slot 322 and a ridge 313 extends from an inner periphery of an opening from which the contact plate splits, the ridge 313 is engaged with the second slot 322. The spring member 32 has an extension portion 320 extending from a top thereof and located beneath the push member 22 of the switch member 2. A second contact point 121 is connected to the second terminal 12 and located beneath the first contact point 311 on the contact portion 31. It is noted that the second end of the contact plate 3 and the free end of the contact portion 31 are deformed in opposite directions when being heated.
When pushing the first end of the switch member 2 as shown in
While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
Number | Name | Date | Kind |
---|---|---|---|
3733571 | Budlane et al. | May 1973 | A |
6452125 | Yu | Sep 2002 | B1 |
6456185 | Yu | Sep 2002 | B1 |
6469610 | Chen | Oct 2002 | B1 |
6884955 | Yu | Apr 2005 | B1 |
6984798 | Lu | Jan 2006 | B1 |
7030726 | Yu | Apr 2006 | B1 |