GB2381385A

GB2381385A - Thermal control

Info

Publication number: GB2381385A
Application number: GB0214566A
Authority: GB
Inventors: Zhicheng Shao
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-25
Filing date: 2002-06-24
Publication date: 2003-04-30
Anticipated expiration: 2022-06-24
Also published as: GB2381385B; GB0214566D0; CN2504753Y; DE20211750U1

Abstract

A thermal control for an electric kettle comprises a base, terminal pins 2, fixed contact 9 and movable contacts 4, and a fusible element 12 to protect the appliance in case of an overheat situation. Bimetallic element 5 operates as a steam control via lever 7 and steam lift pin 14 in the normal manner. Bimetallic element 6 operates as a dry-boil control via dry heating lift pin 8 to switch off the appliance should a normal overheat situation arise, e.g. no water in the kettle. If the dry-boil control should fail, or be forced to operate repeatedly, fusible element 12 melts, allowing flat spring 10 to move pin 13 down and push movable contact 4 away from fixed contact 9, thus switching the appliance permanently off.

Description

APPLIANCE SOCKET WITH TEMPERATURE INDUCED CONTROL STRUCTURE The present invention relates to an appliance socket with temperature induced control structure.

The appliance socket is mainly used in electric heating kettles. It is mounted in the lower part of the kettle body and connected with the electric heating element.

The socket is used for the electric connection between the kettle body and the kettle base and also for the temperature control. The current appliance socket structure includes a socket base, plug pin attached on the base, connecting lug on the plug pin, elastic electrode pieces connecting with the electric heater, a dry heating bimetal sheet and a dry heating lift pin. In addition, there is a fusing lift pin, which is made of plastic and props up the heating metal face with one end. There is a set of elastic electrode press-elastically contacting with the pin connecting lug. There is a spring in the socket base, the spring arm of which presses between the elastic pole piece and the pin connecting lug elastically. The other end of the fusing lift pin presses over the spring. In normal conditions, an elastic contacting is kept between the elastic electrode piece and the pin connecting lug. When the fusing lift pin is shortened, the spring arm will separate the elastic electrode piece and the pin connecting lug and switch off the power supply. The property that the plastic material will melt under predetermining temperature is utilized here. In case of failure of temperature control, the high temperature generated on the metal face will melt and shorten the plastic lift pin. As the electric kettle is used for a long time the fusing lift pin will be in high temperature condition for long time, while the aging process will be accelerated, since the plastic material has an aging feature, so that the temperature control fails is caused, and the safety of the appliance is

decreased.

An object of the present invention is to provide an appliance socket with temperature induced control structure, which implements temperature induced on- off control for the plug pins.

The present invention has been accomplished based on the following technical solution. An appliance socket with temperature induced control structure comprising a socket base, a plug pin fixed on the base, a connecting lug on the plug pin, the elastic electrode pieces connecting with the electric heater, a dry heating bimetal sheet and a dry heating lift pin. A fixed contacting piece is formed between one of the elastic electrode pieces and the connecting lug of the plug pin. Said elastic electrode piece and the connecting lug of the plug pin are all pressed on the fixed contacting piece elastically. A dry heating lift pin which can push up the connecting lug of the plug pin and separates with the fixed contacting piece is set between the said dry heating bimetal sheet and the connecting lug of the plug pin. There is a pressing-down elastic piece attached on the upper end of the base. A bracket that can pull the elastic piece up is set on the pressing-down elastic piece. A metal fastener with low melting point is attached between the pressing-down elastic piece and the bracket and a fusing lift pin is set between the pressing-down elastic piece and the elastic pole piece.

The above and other objects, features and other advantages of the present invention will be more clearly understood and more readily appreciated from the following detailed description of the embodiments of the invention taken in conjunction with the accompanying drawings, in which: Fig. 1 is a schematic drawing showing the structure of the appliance socket with temperature induced control structure according with the present invention; Fig. 2 is a sectional view taken along the line A-A of Fig. 1 ;

Fig. 3 is a sectional view taken along the line B-B of Fig. 1; Fig. 4 is a schematic drawing showing the base cover of the structure shown in Fig. 1 is removed; Fig. 5 is a perspective view showing the stereo-structure of the base cover of the structure shown in Fig. 1 is removed; Fig. 6 is a schematic drawing showing the structure of the pressing-down elastic piece.

Next, an embodiment of the present invention will be described in detail with reference to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. The embodiment is described below in order to explain the present invention by referring to the figures.

As shown in the Figs 1 to 6, an appliance socket with temperature induced control structure of the invention comprises a base 1, a plug pin 2, a connecting lug 3 of plug pin, the elastic electrode pieces 4, a steam bimetal sheet 5, a dry heating bimetal sheet 6, a warping key 7, a dry heating lift pin 8, a fixed contacting piece 9, a pressing-down elastic piece 10, a bracket 11, a metal fastener 12 with low melting point, a fusing lift pin 13 and a steam lift pin 14. Two plug pins 2 are fixed on the base 1 and the connecting lug 3 is connected with the plug pin 2. Two elastic electrode pieces 4 connecting with the electric heater are fixed in the base 1. The spring 16 is set at a portion contacted with the electric heater of one of the elastic electrode pieces 4. A steam bimetal sheet 5 and a dry heating bimetal sheet 6 are fixed on the base 1. After heated, the steam bimetal sheet 5 will deform and activate the warping key 7. The steam lift pin 14 is set between the warping key 7 and other elastic electrode piece 4. The base cover 17 is attached on the base 1 and the dry heating bimetal sheet 6 is attached on the base cover 17. The dry heating lift pin 8 is set between the dry heating bimetal sheet 6 and the connecting lug 3 of plug pin. The fixed contacting piece 9 is set between one of the elastic electrode pieces 4 and

the connecting lug 3 of plug pin. Both said elastic electrode piece 4 and the connecting lug 3 of plug pin are pressed on the fixed contacting piece 9. The dry heating lift pin 8 which can push up the connecting lug 3 of plug pin off the fixed contacting piece 9 is set between the said dry heating bimetal sheet 6 and the connecting lug 3 of plug pin. A pressing-down elastic piece 10 is attached on the upper end of the base 1. The bracket 11 that can press over the elastic piece is set on the pressing-down elastic piece 10. The low-melting point metal fastener 12 may be a rivet made of low melting point metal, such as a rivet made of tin. There are rivet holes on the pressing-down elastic piece 10 and the bracket 11. These two parts are jointed with the rivet made of tin. The fusing lift pin 13 is set between the pressing-down elastic piece 10 and the elastic electrode piece 4. The bracket 11 has an shape like-arch plate structure. The pressing-down elastic piece 10 has a C-shaped plate structure and it has a tab 15 pressed closely under the arch face of the bracket 11. When operating, the bracket 11 is pressed closely to the kettle wall surface. The wall surface is a metal surface and the electric heater is generally set on this surface. When the bracket 11 is pressed to the metal surface too tight, since it is arch shaped, the middle buckling part will be pressed down and the two sides will extend outwards. This ensures good face contact with the metal surface to make reliable temperature induced control, and certain assembling adjustment space can also be obtained.

When the water in the kettle is boiling, the steam is guided to the steam bimetal sheet 5 first. Steam bimetal sheet 5 is heated by the steam and activates, while the warping key 7 is actuated and activated. Then the elastic electrode piece 4 will be pushed up by the steam lift pin 14, to make it separate from the connecting lug 3 of plug pin which is connected with it. The circuit will be formed an open circuit. At this time, the electric heater will be switched off and heating of the water in the kettle will be stopped. This is the normal power-off control for the boiling water. When the water in the kettle has been dried out or there is not any water in the kettle, as there is no steam may be guided to the steam bimetal sheet 5, causing failure of power-off control for the boiling water or when the power-off control for the boiling water fails

itself, the temperature on the container surface will rise continuously. As the temperature rise to the activating temperature of dry heating bimetal sheet 6, the dry heating bimetal sheet 6 will activate to actuate the dry heating lift pin 8, causing the connecting lug 3 of plug pin separating from the fixed contacting piece 9 to make the circuit opened. The electric heater will also be switched off and heating of the water in the kettle will be stopped. This is the case of dry heating control. Once the temperature decreases, the dry heating bimetal sheet 6 will reset. If no one is looking after the operation of the electric heating kettle, the electric heater will be switched on and heating continuously, thereby causing power off to make the temperature decreasing. The process will repeat continuously and the temperature of the electric heating kettle will be kept above 100 DC. Lasting of high temperature for long time will cause an aging or a damage for the plastic parts, leading to failure of temperature control and the electric heating kettle may cause fire. When the boiling water power-off control and dry heating control fails, the temperature of the kettle will rise continuously. Since the low melting point metal fastener 12 presses to the container surface, when the temperature reaches the melting point of the metal fastener 12 it will melt, while the pressing-down elastic piece 10 will separate from the bracket 11. At the same time, the fusing lift pin 13 will be actuated to make the elastic pole piece 4 separating from the fixed contact piece 9. Thus the power circuit of the electric heating kettle will be cut off thoroughly and will not be closed again to prevent the fire caused by failure of temperature control of the electric heating kettle effectively.

Comparing with the prior art, the present invention can obtain the following advantages: the temperature control with fusing protection is accurate and it is not apt to fail. Furthermore, the multilevel protection provides a temperature control of higher safety and reliability. The reason is as following : a pressing-down elastic piece is attached on the upper end of the base in the present invention, a metal fastener with low melting point is attached between the pressing-down elastic piece and the bracket and a fusing lift pin is set between the pressing-down elastic piece and the elastic pole piece.

Claims

1. An appliance socket with temperature induced control structure comprising a base (1), a plug pin (2) attached on the base (1), a connecting lug (3) of plug pin, the elastic electrode pieces (4) connecting with the electric heater, a dry heating bimetal sheet (6) and a dry heating lift pin (8), wherein a fixed contacting piece (9) is set between one of the elastic electrode pieces (4) and the connecting lug (3) of plug pin, said elastic electrode piece (4) and the connecting lug (3) of plug pin are all pressed over the fixed contacting piece (9) elastically, said dry heating lift pin (8) which can push up the connecting lug (3) of plug pin off the fixed contacting piece (9) is set between said dry heating bimetal sheet (6) and the connecting lug (3) of plug pin; a pressing-down elastic piece (10) is attached on the upper end of the base; a bracket (11) that can pull the elastic piece up is set on the pressing-down elastic piece (10); a metal fastener (12) with low melting point is attached between said pressing-down elastic piece (10) and said bracket (11) and a fusing lift pin (13) is set between said pressing-down elastic piece (10) and said elastic electrode piece (4).

2. The appliance socket with temperature induced control structure according to claim 1, wherein the said bracket (11) has a shape like arch plate structure.

3. The appliance socket with temperature induced control structure according to claim 1 or 2, wherein said pressing-down elastic piece (10) has C-shaped plate structure and it has a tab (15) pressed closely under the arch face of the bracket (11).

4. The appliance socket with temperature induced control structure according to any of Claims 1,2 and 3, wherein other elastic electrode piece (4) is elastically connected with said connecting lug (3) of plug pin; a warping key (7) and a steam bimetal sheet (5) which may activate the warping key (7) are set on the said base

(1); a steam lift pin (14) is set between said warping key (7) and said connecting lug (3) of plug pin.

5. An appliance socket substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

I. An appliance socket for an electric heater, the socket including a temperature induced controller and comprising: a base (1), a plug pin (2) attached to the base (1), a lug (3) connected to the plug pin (2), and elastic electrode pieces (4) for connection to the electric heater; a dry heating bimetal sheet (6) and a dry heating lift pin (8); a fixed contacting piece (9) set between a first one of the elastic electrode pieces (4) and the lug (3), the first elastic electrode piece (4) and the lug being pressed onto the fixed contacting piece (9), the dry heating lift pin (8) being set between the dry heating bimetal sheet (6) and the lug (3); a pressing-down elastic piece (10) attached to the base (1), a bracket (11), a metal fastner (12) having a melting point selected to exceed normal operating temperatures of the heater and attaching the pressing-down elastic piece (10) under tension to the bracket (11), and a fusing lift pin (13) set between the pressing-down elastic piece (10) and the first elastic electrode piece (4), wherein upon reaching an activating temperature, the dry heating bimetal sheet (6) is arranged to actuate to cause the dry heating lift pin (8) move and disconnect the lug (3) from the fixed contacting piece (9) thereby forming an open circuit, upon reaching its melting point, the fastner being arranged to disconnect the pressing-down elastic piece (10) from the bracket, the pressing-down elastic piece (10) thereby moving the fusing lift pin (13) to disconnect the first elastic electrode piece (4) from the fixed contacting piece (9) thereby forming an open circuit.

2. An appliance socket according to claim 1, wherein the bracket is an arch shape.

3. An appliance socket according to claim 1 or 2, wherein the pressing-down elastic piece (10) is a c-shaped plate and includes a tab (15) pressed closely under the arch face of the bracket (11).

4. An appliance socket according to claim 1,2 or 3, further comprising a warping key (7) and a steam bimetal sheet (5) set on the base (1), a steam lift pin (14) being set between the Amendments to the claims have been filed as follows

warping key (7) and the lug (3), wherein a second one of the elastic electrode pieces (4) is elastically connected to the lug (3), the warping key being actuable by said steam bimetal sheet (5) upon reaching an activating temperature to cause the steam lift pin (14) to move and disconnect the second elastic electrode piece (4) from the lug (3), thereby forming an open circuit.