GB2469445A

GB2469445A - Switch with bimetallic protection strip

Info

Publication number: GB2469445A
Application number: GB0906296A
Authority: GB
Inventors: Jianping Wang
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-04-14
Filing date: 2009-04-14
Publication date: 2010-10-20
Also published as: GB0906296D0

Abstract

A switch has one or more contained bimetallic strips 2. Incorrect or excessive current causes the strip(s) to deform, and cut the current in the switch. Correct operation of the switch may be indicated by a bulb 12 which may shine through a light transparent switch 7.

Description

ELECTRICAL CURRENT PROTECTION SWITCH

The present invention relates to a type of electrical current protection switch, and specifically it relates to a unit which is capable of cutting off a power source by the flicking off of a metallic strip when a current overload occurs.

Currently, most domestic electrical appliances are fitted with some kind of current overload protection device. Chinese utility model number 200620160085.0 discloses a system comprising a current overload protection device. However, this does not provide effective circuit protection when the live (L) contact and the neutral (N) contact or N contact cables of the system are connected in reverse, and consequently improvements have been made to this basic system.

It is an object of the present invention to provide an electrical current protection switch which ensures effective circuit safety when an L contact and an N contact or N contact cables are connected in reverse. Both the L contact and the N contact possess bimetallic strips and, once the current exceeds a certain value, the bimetallic strips heat up and deform, causing automatic disconnection of the electrical circuit.

The object of this invention is achieved by a type of electrical current protection switch, consisting of four cable connectors and an external case, a plate, a cable entry support, a cable exit support and a neon bulb; the external case consists of a switch inserted into the main body; the switch being inserted into the centre of the top of the main body, there being two columns on both sides of the switch, the columns being connected to the plate and the bimetallic strips of the corresponding cable entry support being beneath the plate; there being a lengthened point on the L or N contacts of the cable exit supports, beneath which there is a resistor, there being bimetallic strips connected to the top of the cable entry supports, the centre of the metallic strips being shaped like the lower half of a sphere; wherein the two cable exit supports of the four cable connectors possess bent sections, on which there are fixed contacts; the two cable entry supports possess bent sections, which are soldered to the bimetallic strips, there being a contact at one end of the bimetallic strips, said contact corresponding to another contact on top of the cable exit support; the aforementioned neon bulb being located beneath the switch, the corresponding connectors being connected to the bottom of the resistor, the top of the plate fitting over the columns of the switch, and the bimetallic strip being suspended from the opening at the bottom of the plate.

When there is excessive current or a short-circuit, the effect of the bimetallic strips in the electrical current protection switch deforming to differing extents due to the effects of heat results in automatic disconnection of the electrical circuit. This obviates the need for manual operation, thus ensuring that electrical apparatus operates only at its standard rated current, and hence effectively protecting the electrical equipment. In addition, the electrical current protection switch may be re-used repeatedly, has a simple construction and is easily installed.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-Figure 1 displays the internal structure of an electrical current protection switch of the invention; Figure 2 is a schematic section through the electrical current protection switch; and Figure 3 is a schematic detail of a neon bulb connected to resistors of the electrical current protection switch.

In Figure 1, 1 is the left cover plate, 2 is a bimetallic strip, 3 is a silver contact, 4 is a resistor, 5 is a spring, 6 is the main body, 7 is the switch, 8 is the right cover plate, 9 is a cable entry support, 10 is a cable exit support, 11 is an ejector pin, 12 is a neon bulb, 13 is a plate.

The following embodiment is given for the purpose of gaining a better understanding of the invention. However, the invention should not be seen as being restricted to this embodiment.

In conjunction with Figures 1 to 3, an electrical current protection switch comprises an external case, a pair of plates 13, a pair of cable entry supports 9, a pair of cable exit supports 10, four cable connectors 20 and a neon bulb 12.

The external case comprises a button or switch 7 inserted into a main body 6 and the switch 7 is arranged to rock about a central pivot 21. The switch 7 is inserted into the centre of the top of the main body 6, and there is a column 22 on either side of the switch 7. Each column 22 has the top of a respective said plate 13 fitted over it, and a bimetallic strip 2 of the corresponding cable entry support 9 is suspended from an opening 29 in the bottom region of the plate 13.

The underside of the centre of each bimetallic strip 2 is dome-shaped 24 like the lower half of a sphere, and there is a silver contact 3 at one end of each bimetallic strip 2. The two cable entry supports 9 each possess a bent section 27, which is soldered to the bimetallic strip 2 of the support 9. The two cable exit supports 10 of the four cable connectors 20 each possess a bent section 25, on top of which there is a fixed contact 26. The fixed contact 26 corresponds to the silver contact 3 of the corresponding bimetallic strip 2.

There is a lengthened point 23 on the L or N contacts of each cable exit support 10, against which there is a resistor 4. A bottom of each resistor 4 is connected to a corresponding connector 28 of the neon bulb 12 and the bulb 12 having two such connectors 28 is located beneath the switch 7.

When the switch 7 is used for connecting or disconnecting, the top of the switch 7 is pressed, causing the dome-shaped contact 24 in the centre of each bimetallic strip 2 to come into contact with the top of a corresponding ejector pin 11 of the main body 6. Each bimetallic strip 2 is capable of moving in both directions, in order to allow the contacts to meet or separate as required. The bimetallic strips 2 connected to the cable entry supports 9 each possess the silver contact 3, and there is the fixed contact 26 located on the corresponding cable exit support 10 beneath. When the current is connected, the protruding contact 23 on the cable exit support 10 comes into contact with one end of the resistor 4, and a spring 5 at the other end of the resistor 4 forms a contact with a respective said connector 28 of the neon bulb 12, causing the neon bulb 12 to be illuminated, thus indicating normal function.

Claims

Claims: 1. An electrical current protection switch, comprising a bulb; at least one plate; an external casing comprising a switch inserted into a main body, the switch having at least one column, the column being connected to the plate; and cable connectors with at least one cable entry support and at least one cable exit support; the cable entry support having a bimetallic strip substantially beneath the plate and the bimetallic strip having a dome-shaped protrusion; the cable exit support comprising a contact with a lengthened point, the lengthened point arranged to contact a resistor of the electrical current protection switch, and a connector of said bulb being connected to the resistor.
2. The electrical current protection switch according to claim 1, wherein the or each bimetallic strip is held by a corresponding said plate.
3. The electrical current protection switch according to claim 1 or 2, wherein actuation of the switch causes the or each bimetallic strip to be in contact with the corresponding cable exit support, and deformation of the or each bimetallic strip automatically disconnects the bimetallic strip from the cable exit support.
4. The electrical current protection switch according to claim 1, 2 or 3, wherein actuation of the switch causes the dome-shaped protrusion of the or each bimetallic strip to come into contact with the main body.
5. The electrical current protection switch according to any preceding claim, the bulb is arranged to illuminate when a current is connected.
6. The electrical current protection switch according to any preceding claim, including a said column on two opposing sides of the switch and a corresponding said plate being connected to each column.
7. The electrical current protection switch according to any preceding claim, including two said cable entry supports, two said cable exit supports and a said cable connector for each support.
8. The electrical current protection switch according to claim 7, wherein each cable exit support possesses a bent section, on which there is a fixed contact, and each cable entry support possesses a bent section which is soldered to a said bimetallic strip, the bimetallic strip having a contact at one end, the contact corresponding to another contact on top of the cable exit support.
9. The electrical current protection switch according to any preceding claim, wherein the top of the plate fits over the column of the switch, the bimetallic strip being suspended from an opening in the bottom region of the plate.
10. The electrical current protection switch according to any preceding claim, wherein the contact of the cable exit support is an L or N contact.
11. The electrical current protection switch according to any preceding claim, wherein the dome-shaped protrusion is located at the centre of the bimetallic strip.
12. The electrical current protection switch according to any preceding claim, wherein the switch is inserted into the centre of the top of the main body.
13. The electrical current protection switch according to any preceding claim, wherein the bulb is located beneath the switch.
14. The electrical current protection switch according to any preceding claim, wherein the bulb is a neon bulb.
15. The electrical current protection switch according to any preceding claim, wherein the or each column is round.
16. An electrical current protection switch constructed substantially as hereinbefore described with reference to the accompanying drawings.