GB2368980A

GB2368980A - Rotatable electrical joint,joint holder and cordless electrical appliance

Info

Publication number: GB2368980A
Application number: GB0200857A
Authority: GB
Inventors: Zhicheng Shao
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-07-15
Filing date: 2000-04-10
Publication date: 2002-05-15
Anticipated expiration: 2020-04-10
Also published as: AU769525B2; WO2001006601A1; CA2378979A1; GB2368980B; AU4097600A; DE10084812T1; GB0200857D0

Abstract

The invention relates to a rotatable electrical joint, joint holder and cordless electrical appliance. Prior art electrical connectors have not good coupling mechanical strength, electrical contact, security, and cordless electrical appliance have cloggy area when taken away and placed. The invention directs to solve aforementioned questions. Rotating electrical union joint provides annular electrode and side spring contact piece on front-end surface and outer surface of cylindric joint. Electrical joint holder provides annular electrode and bottom contact on inner sidewall and bottom in cavity, respectively. Cordless electrical appliance provides rotatable electrical joint and joint holder on the bottom of container and base unit, respectively. It provides advantages such as substantial mechanical connection, reliable electrical contact, security, compact structure, and easy to manufacture parts.

Description

236898) -

ROTATABLE CONNECTOR PLUG, CONNECTOR SOCKET AND CORDLESS

ELECTRIC HEATING APPLIANCE

s FIELD OF THE INVENTION

The invention relates to a cordless electric heating appliance and its connector plug, more particularly, to a rotatable connector plug, a connector socket connected to an electric appliance and a cordless electric heating appliance used for cordless electric heating kettle etc. BACKGROUND OF THE INVENTION

In China Patent Application ON 94194173.6, a cordless electric appilance and its connector plug are disclosed, in which said cordless electric heating appliance mainly directs to a cordless boiler, comprising an immersion type electric heater, a 15 tank, a control unit, a base unit for placing the tank, and connector plug provided between the bottom of the tank and the base unit. Since the immersion heater is employed, the control unit is provided at the lower side of the bottom of the tank to be facilitated for utilization of power connector plug of the immersion heater, because a certain volume is occupied by the control unit, a space is added at the 20 bottom of the tank, and a complicated electric connector plug structure is formed at the bottom of tank.

The connector plug used in the cordless electric appliance comprises a male connector and a female connector. Only one male connector is provided at the center used for connecting to a binding post of a power source, an annular power :5 terminal which is concentric with the binding post and an annular connecting terminal used for grounding are provided in the body of male connector. While a circular hole and an annular opening for receiving the binding post and the annular power terminal are provided on the female connector. A flat spring connected to the binding post of the male connector is provided in the circular hole of the female so connector, and a flat spring connected to the annular power terminal is provided in

r À d}. the annular opening, while a spring contact connected to the annular terminal used for grounding is provided on the outer surface of female connector. Since the flat spring in the circular hole and the annular opening are connected to the power source, these two holes should not be too large in design, to prevent electric shock s due to finger contacting the flat spring, thus the diameter of binding post is limited. If it is designed too thick, a good performance in electric conduction and connector plug to the electric appliance is acquired, but the circular bole's diameter is too large, and electric shock may occur. If it is designed too thin, on the one hand, difficulties appear in fabrication for connecting the binding post and conducting piece, and to effective power transmission is directly affected by the degree of connecting tightness therebetween. While one annular connecting terminal is located between another annular terminal and the binding post, only one end is fixed on the male connector without other support, the fixing is unstable, frequent plugging tencis to cause loose, and difficulties are resulted in power transmission and butt joint of the Is female and the male connectors. On the other hand, due to the small contact surface between the surfaces of the binding post and the female connector, electric appliance contact shall be seriously affected by slight surface oxidation. If the junction is loosen, heat shall be generated after power turn on, even strike arc may occur, oxidation occurs between the connector plugs, resistance increased, severe 20 heat generation occurs, a vicious cycle is formed, and resulted in burning out of the plastic casing of the connector socket. If the contact clamps the electrode too tight, the female and the male connectors tend to be clogged, and hard to be separated; while if the electrode is loose, then poor electric connecting effect is achieved.

OBJECT OF THE INVENTION

25 An object of the invention is to provide a rotatable connector plug having the features of omnidirectional, stable, and reliable electric connection and good safety performance used for a cordless electric heating appliance.

Another object of the invention is to provide a connector socket having the features of convenient for the rotation of the rotatable connector plug, stable and 30 reliable electric connection and good safety performance used for the cordless

t À - r e e .. 1

electric heater.

A further object of the invention is to provide a cordless electric heating appliance having the features of easy placement in any inclination, rotatable, stable and reliable electric connection and good safety performance used for the electric s appliance.

SUMARRY OF INVENTION

To accomplish the first object of the invention, said rotatable connector plug comprises a binding post, an annular electrode piece and a side spring contact to piece connected to a power terminal of the connector plug are provided at the head end surface and the outer surface of the binding post respectively.

To accomplish the second object of the invention, the connector socket which can receive aforesaid rotatable connector plug comprises a cavity for receiving the connector plug, an annular electrode and a bottom contact connected to a power 15 terminal of the connector socket are provided on the inner side wall and at bottom of said cavity respectively.

To accomplish the third object of the invention, said cordless electric heating appliance comprises a container, a base for placing the container, a pedestal is provided at the bottom of the container, the rotatable connector plug is provided in do the pedestal, the connector socket is correspondingly provided on the base, the annular electrode piece and a side spring contact piece connected to the power terminal of the connector plug are provided on the head end surface and the outer surface of the binding post of the rotatable connector plug respectively, the connector socket has a cavity for receiving the binding post, and the annular as electrode piece and the bottom contact connected to the power terminal of the pedestal are provided on the inner side wall and at bottom of said cavity respectively. BEIEF DESCRIPTION OF THE DRAWINGS

30 The drawings are described as follows, in which: FIG.1 is a view showing the structure of a rotatable connector plug;

.. . - FIG.2 is a top view of the rotatable connector plug shown in FIG.1; FIG.3 is a bottom view of the rotatable connector plug shown in FIG.1; FIG.4 is a view showing the structure of a connector socket; FIG.5 is a top view of the connector socket shown in FIG.4; s FIG.6 is an bottom view of the connector socket shown in FIG.4; FIG.7 is a view showing the structure of the rotatable connector plug in FIG.1 plugged-in with the connector socket in FIG.4; FIG.8 is view showing another structure of the rotatable connector plug; FIG.9 is a top view of the rotatable connector plug shown in FIG.8; to FIG.10 is a view showing the structure of the rotatable connector plug in FIG.8 plugged-in with the connector socket in FIG.4; FIG. 11 is a partial state diagram of a dry burning ejector pin in FIG. 1 0 depressing a side spring contact piece; FIG.12 is a partial state diagram of an overtemperature fusing ejector pin in 15 FIG.10 jacking up the side spring contact piece upwards; FIG.13 is a partial cross sectional view taken along direction A in FIG.12; FIG.14 is a view showing the punching structure of an annular electrode piece in FIG.7; FIG.15 is a view showing the structure of a cordless electric heating appliance.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the cordless electric heating appliance, rotatable connector plug and connector socket of the invention shall be further described in detail with reference to the drawings: 25 As shown in FIG.1, 2, 3, said rotatable connector plug according to the present embodiment comprises an injection molded plastic member having a binding post 1, and an annular electrode piece 6 made of copper sheets is provided on the head end surface of the binding post 1. On said annular electrode piece 6, a folding wing 33 connected to its power terminal 5 is provided, as shown in FIG.14, so said folding wing 33 and annular electrode piece 6 are integral structured metal

O r À members. Three fixing holes 8 which can be penetrated by said folding wing 33 are provided in the end surface of sad binding post 1, the folding wing 33 penetrates the fixing holes and are bonded so as to be buckled in the plastic member of the binding post 1, and the annular electrode piece 6 can be firmly fastened on the head end 5 surface of the binding post 1. A copper power terminal 5 connected to a power line is provided on the connector plug, the power terminal 5 is made of copper sheets, electric connection between the folding wing 33 and the copper power terminal 5 is accomplishd by welding, the welding point is located in the sandwich of the binding post 1, thus the connection is firm and reliable. A side spring contact piece 7 is to mounted on the outer surface of the binding post 1. The exposed portion of the binding post 1 is arc shaped, this is convenient for it to be pushed into from the side wall of the binding post, and the side spring contact piece 7 and another power terminal 5 of the connector plug are integral structures made of copper sheets. Side spring contact piece 7 has good elasticity.

In many electric appliances, in consideration of safety, grounding should be provided, therefore a socket 2 is provided at the center of said binding post 1, a grounded spring contact piece 4 is mounted in said socket 2, grounded spring contact piece 4 and ground wire connecting terminal 3 of the connector plug are integral structures made of copper sheets, which have good elasticity concurrently.

JO In a cordless electric heating appliance, considering when the temperature of the heater therein rises to a certain value, the power should be turned off so as to ensure the appliance not to be burnt out due to the increasing of the temperature.

For instance, in an electric kettle, when the water in the kettle is burned up. The temperature of the whole kettle shall rise continuously, thus dry burning protection is as needed. As shown is FIGS and 9, to accomplish dry burning protection, the rotatable connector plug comprises a binding post 1, an annular electrode piece 6 and a side spring contact piece 7 connected to the power terminal 5 of the connector plug are provided on the head end surface and the outer surface of the binding post 1 respectively, and a dry burning ejector pin 35 extending to the tail end surface 39 so and being able to jack up the side spring contact piece 7 is provided in the binding

- post 1. A rack wing 40 which can be jacked up by dry burning ejector pin 35 is provided on said side spring contact piece 7, the tip of dry burning ejector pin 35 is inclined wedge shaped, so as to jack up the rack wing 40. A ring-shaped temperature sensing actuator 36 having an annular tongue piece in the middle is s against the tip of dry burning ejector pin 35. The temperature sensing actuator can be a bimetal sheet. As shown in FIG 10-13, when the water in the kettle is burned up, bottom temperature of the kettle rises, the actuator acts and depresses the dry burning ejector pin, the tip of inclined wedge pushes the rack wing 40 to the right, the exposed portion of the arc-shaped side spring contact piece 7 contracts into the 10 binding post, power is turned off, thereby heating is stopped to perform dry burning protection. When water is refilled into the kettle, bottom temperature of the kettle decreases to restore the temperature sensing actuator, its tongue piece pulls up the dry burning ejector pin, the side spring contact piece shots out externally, thus it enables the power to be burned on repeatedly. Said tail end surface 39 is formed by 15 a metal cover having a central hole, the actuator 36 is made to be emerged from the tail end surface 39 of binding post 1, so as to contact with the heater required to be induced. Since the metal cover is non-deforming in high temperature, mounted at the tail end surface 39 of binding post 1, thus the rotatable connector plug can be directly placed snuggled up to the heater, heat generated by the heater shall not be 20 added to the plastic member directly, while it is conducted to the plastic member via the cover rim, thereby heat adding to the plastic member is greatly reduced so that melting of the plastic member due to overtemperature is avoided.

In application, temperature control and dry burning protection may be fail due to various reasons, and the heater in the electric heating appliance may be heated :5 continuously. To avoid uncontrollable fire caused by burn down of the electric heating appliance, an overtemperature fusing ejector pin 37 extending to the tail end surface 39 in binding post 1 and being able to hook up the side spring contact piece 7 is provided, and in the binding post 1, an overtemperature cutting off spring 38 which can jack up the overtemperature fusing ejector pin 37 is provided on the so bottom. A rack wing 40 which can be jacked up by the overtemperature fusing

_ / À T À À

:,.. :,

. ejector pin 37 is provided on said side spring contact 7 piece. Said overtemperature fusing ejector pin is L-shaped, having an inclined wedge on the barb against the rack wing 40. When the upper end of the overtemperature fusing ejector pin melts, the whole pin is jacked up by the overtemperature cutting off spring thereunder, the side s spring contact piece is jacked up inwards permanently by the barb inclined wedge, and the power source turns on until it is completely repaired.

As shown in FIG 4-6, a connector socket which can receive aforesaid rotatable connector plug comprises a cavity 9 for receiving the connector plug, and annular electrode 13 and bottom contact 14 connected to power terminal 12 of the connector To socket are provided on the inner sidewall and at bottom of said cavity 9 respectively.

To be convenient for matching with aforesaid rotatable connector plug required to be grounded, a central conducting post 10 connected to grounded terminal 11 of the connector socket is provided at the center of said cavity 9. A cover 16 being able to seal the cavity entrance and a spring 15 for restoring the cover 16 are provided on as said central conducting post 10. A guide groove 17 is provided on said central conducting post 10, a locating lug 18 clamped in the guide groove 17 and a through hole 19 which can expose the bottom contact 14 are provided on cover 16 correspondingly. An annular inclined guide hook 20 not only be convenient for inserting the connector plug, but also can block the cover 16 from sliding out is To provided at the edge of entrance of said cavity 9. Said central conducting post 10 is located nearest to the cavity's opening face, the annular electrode 13 is in the middle, and the bottom contact 14 is farthest. As shown in FIG.7, when the rotatable connector plug is inserted, central conducting post 10 is in contact with the grounded spring contact piece 4 firstly, making the appliance to be safely grounded, then 25 annular electrode 13 is in contact with the side spring contact piece 7, i.e. in which a power source is turned on, at this time, no electric spark is generated in contact, a conventional copper contact may be employed for the contact of side spring contact piece 7, finally the bottom contact 14 is in contact with the annular electrode 6, at this time, a largest electric spark is generated, and a silver contact can be provided 30 on the bottom contact.

À. e e e a _ t À -

.. , As shown in FIG.15, a cordless electric heating appliance comprises a water container 21, a base 22 for placing the container, a pedestal 23 is provided at the bottom of the container 21, a rotatable connector plug 24 is provided in the pedestal 23, a connector socket 25 provided on the base 22 correspondingly, an annular s electrode piece 6 and a side spring contact piece 7 connected to the power terminal 5 of the connector plug are provided on the bead end surface and the outer surface of the binding post 1 of the rotatable connector plug 24 respectively, the connector socket 25 has a cavity 9 for receiving the binding post 1, an annular electrode 13 and a bottom contact 14 connected to the power terminal 12 of the connector socket to are provided on the inner sidewall and at bottom of said cavity 9 respectively. A socket 2 is provided at the center of said binding post 1, a grounded spring contact piece 4 connected to a ground terminal 3 of the connector socket is provided in said socket 2, and a central conducting pot 10 connected to the ground terminal 11 of the connector socket is provided at the center of said cavity 9. A cover 16 for sealing the 15 cavity entrance and a spring 15 for restoring cover 16 are provided on central conducting post 10 respectively. The rotatable connector plug provided in the pedestal 23 can employ any structural forms of aforesaid connector plug. The connector socket 25 provided on the base 22 can also employ any structural forms of aforesaid connector socket. When the power line on the pedestal turns on tr -' 20 power source, the annular electrode and bottom contact of the connector sot energized, since the cover is blocking the cavity entrance, only the centr-, conducting post is exposed and grounded, thus enable the surface of the whole connector socket to be uncharged and the electric appliance having good performance. In the process of putting the container on the pedestal, firstly, the 25 rotatable connector plug on the bottom of the container is in contact with the connector socket mounted on the base, and the connector plug is easily inserted into the cavity via the inclined guide hook on the edge of cavity entrance. A guide groove 17 is provided on the central conducting post 10, a locating lug 18 clamped in guide groove 17 and a through hole 19 for exposing the bottom contact 14 are so correspondingly provided on the cover 16. The guide groove 17 is provided on

-.. : ? central conducting post 10, while locating lug 18 clamped in guide groove 17 and a through hole 19 which can expose the bottom contact 14 are correspondingly provided on the cover 16. The front end surface of the whole binding post is in contact with the cover, since the fug is embedded into the guide groove, the cover s shall be steadily depressed, the bottom contact is aligned to the through hole and no dislocation occurs, in the process, the central conducting post 10 is firstly in contact with the grounded spring contact piece 4, making the electric kettle to be safely grounded, then the annular electrode 13 is in contact with the side spring contact piece 7, finally the bottom contact 14 is in contact with the annular electrode piece 6, lo and an electric spark is generated on the lowest bottom at this moment. Since a silver contact is in contact with the annular electrode piece at the bottom, the silver contact has a good anti-oxidation performance, the annular electrode has a large contact surface, even if partial oxidation occurs, the oxidation point can be staggered when the container is turned over a small angle, and they shall be in well 15 electric contact. When the container is removed from the base, since the restoring spring on the central conducting post jacks up the cover, on one hand, the rotatable connector plug rapidly separates from the connector socket, such a contradiction is avoided, i.e. since the two contact pieces are so tightly gripped by the spring clamping, electric contact is reliable, while in separation, the base is easily brought do up by the container, spring clamping between the contact pieces is too loose, and the electric contact is poor. After the container departs from the base, the cover seals the cavity entrance to ensure the safety of electric appliance, and to prevent the finger from touching to the electrode. A fixed post 28 is provided on said lower cover face 26, the fixed post 28 is sheathed with spring 29, a fixed fug 42 on the :5 rotatable connector plug 24 is positioned on fixed post 28 via a fastener 30, thereby the rotatable connector plug is elastically fastened on the lower cover face 26 of the pedestal 23. Since not only the binding post on the bottom of container should be aligned in assembling to the connector socket on the base, but also the temperature sensing actuator and fusing ejector pin on the back face of rotatable connector plug 30 should be snuggled up to the bottom face of container, with the above structure, it is

r r f e ' '

convenient to assemble the lower cover face onto the base in alignment, then the rotatable connector plug is fitted on the lower cover face, and finally the lower cover face is fixed at the bottom of container. When the tail end surface 39 of said rotatable connector plug is against the bottom of the container, the spring is compressed, a s clearance 32 exists between it and the tip 31 of the fastener 30 so as to be convenient for mounting clearance adjustment. At this time, the temperature sensing actuator 36 and the overtemperature ejector pin 37 are against the bottom of the container. In application, normally, when the water in the container is boiling, since the vapor passes over a temperature controller 41 provided in container 21 to to actuate it, the electric heater on the bottom plate 34 of the container is turned off.

While the water in container is burned up or no water is filled in the container, the bottom temperature of container rises rapidly, at this moment, since no vapor is induced by the temperature controller, the power source can not be controlled to be cut off, while the temperature sensing actuator shall induce the continuously rising as temperature of the bottom of the container so as to be actuated, and the dry burning ejector pin is driven to turn off the power source between the rotatable connector plug and the connector socket. When water is refilled into the container, the temperature sensing actuator is restored, the power source between the rotatable connector plug and connector socket is turned on, and a dry burning protector is go formed. If the dry burning protector is fail, tthe bottom temperature of the container rises continuously until the tip of the fusing ejector pin melts, then the overtemperature fusing spring jacks up the fusing ejector pin, similarly turns off the power source between the rotatable connector plug and connector socket, this overtemperature protector cannot be restored, thereby effectively prevent the fire 25 danger from occuring. Aforesaid rotatable connector plug and connector socket can also be used for electric heating appliance such as a cordless electric iron etc., the description thereof is omitted here.

POSITIVE EFFECT OF THE INVENTION COMPARED WITH THE PRIOR ART:

so In conclusion, by comparing the present invention with the prior art, we know

. ... :. -: that: The rotatable connector plug employs an annular electrode piece and a side spring contact piece structure on the binding post. It has the advantages of a large annular surface of the electrode, a flat surface, a large contact surface, firm s mechanical connection, and reliable electrical contact. High temperature protection devices such as the overtemperature fusing ejector pin and the fusing ejector pin are provided on the side of side spring contact piece, which have the advantages of good safety protection performance, compact in structure, simple in component machining and integral assembly.

to In the connector socket, the annular electrode and bottom contact connected to the power terminal of the connector socket respectively are provided on the inner sidewall and at bottom of the cavity receiving the connector plug. It has the advantages of complementary abutment of a large and a small electrodes of the rotatable connector plug, reliable electrical contact, firm mechanical connection, a us restoring cover being provided on the central conducting post to prevent the finger electric shock from occurring, and having good safety performance of the electric appliance. The cordless electric heating appliance employs the structural scheme of providing a pedestal at the bottom of the container, the rotatable connector plug is so mounted in the pedestal, the connector socket is correspondingly provided on the base, and the rotatable connector plug is elastically fastened on the lower cover face.

It has the advantages of the omnidirectional placement of the container on the base, reliable electrical therebetween, firm mechanical connection, easy in placing alignment, simple in removal, good electric appliance security, perfect heating :5 protection performance, easy and simple assembly etc.

Claims

-. t, À À . CL AIMS

1. A rotatable connector plug, comprising a binding post (1), wherein an annular electrode piece (6) and a side spring contact piece (7) connected to a power 5 terminal (5) of the connector plug are provided on the head end surface and the outer surface of the binding post (1) respectively.

2. The rotatable connector plug according to claim 1, wherein a socket (2) is provided at the center of said binding post (1), a grounded spring contact piece (4) connected to a ground line connecting terminal (3) of the connector plug is provided to in said socket (2).

3. The rotatable connector plug according to claim 1 or 2, wherin a folding wing (33) connected to the power terminal (5) is provided on said annular electrode piece (6)

4. The rotatable connector plug according to claim 3, wherein said folding wing 15 (33) and said annular electrode piece (6) are metal members having an integral structure.

5. The rotatable connector plug according to claim 4, wherein a fixing hole (8) which can be penetrated by said folding wing (33) is provided at an end surface of said binding post (1).

do

6. The rotatable connector plug according to claim 1 or 2, wherein a dry burning ejector pin (35) extending to the tail end surface (39) of said binding post (1 and being able to jack up a side spring contact piece (7) is provided in the binding post (1), and on the tail end surface (39) of said binding post (1), a temperature sensing actuator (36) is against the tip of said dry burning ejector pin (35).

25

7. The rotatable connector plug according to claim 6, wherein said tail end surface (39) is formed by a metal cover.

8. The rotatable connector plug according to claim 6 or 7, wherein a rack wing (40) which can be jacked up by the dry burning ejector pin (35) is provided on said side spring contact piece (7).

So

9. The rotatable connector plug according to claim 1 or 2, wherein an

r À * À * .. * -

overtemperature fusing ejector pin (37) extending to the tail end surface (39) of the binding post (1) and being able to hook up the side spring contact piece (7) is provided in the binding post (1), an in said binding post (1), an overtemperature cutting off spring (38) which can spring up the overtemperature ejector pin (37) is 5 provided thereon.

10. The rotatable connector plug according to claim 9, wherein said tail end surface (59) is formed by a metal cover.

11. The rotatable connector plug according to claim 10, wherein a rack wing (40) which can be jacked up by an overtemperature fusing ejector pin (37) is to provided on said side spring contact piece (7).

12. A connector socket being able to receive the rotatable connector plug and comprising a cavity which can receive the connector plug, wherein an annular electrode (13) and a bottom contact (14) connected to a power terminal (12) of the connector socket are provided on the inner sidewall and at bottom of said cavity (9) Is respectively.

13. The connector socket according to claim 12, wherein a central conducting post (10) connected to a ground terminal (11) of the connector socket is provided at the center of said cavity (9).

14. The connector socket according to claim 13, wherein a cover (16) which So can seal the cavity entrance and a spring (15) which can restore the cover (16) are provided on said central conducting post (10).

15. The connector socket according to claim 14, wherein a guide groove (17) is provided on said central conducting post (10), a locating lug (18) clamped in guide groove (17) and a through hole (19) which can expose the bottom contact (14) are as correspondingly provided on cover (16).

16. The connector socket according to claim 14 or 15, wherein an inclined guide hook (20), which is not only convenient to be entered by the connector plug, but also able to block the cover (16) from sliding out, is provided at the edge of said cavity (9) entrance.

30

17. The connector socket according to claim 13, 14 or 15, wherein said central

d. - i conducting post (10) is located nearest to the cavity opening face, said annular electrode (13) is in the middle, and said bottom contact (14) is farthest from the cavity opening face.

18. A cordless electric appliance, comprising a container (21), a base (22) for s placing the container, a pedestal (23) provided on the bottom of the container (21), a rotatable connector plug (24) provided in the pedestal (23), a connector socket (25) provided on base (22) correspondingly, wherein an annular electrode piece (6) and a side spring contact piece (7) connected to the power terminal (5) of the connector plug are provided on the head end surface and outer surface of said binding post (1) 10 of the rotatable connector plug respectively, a cavity (9) which can receive the binding post (1) is provided in the connector socket (25), an annular electrode (13) and a bottom contact (14) connected to the power terminal (12) of the connector socket are provided on the inner sidewall and at the bottom of said cavity (9) respectively.

19. The cordless electric heating appliance according to claim 18, wherein a socket (2) is provided at the center of said binding post (1), a grounded spring contact piece (4) connected to ground line connecting terminal (3) of the connector plug is provided in said socket (2), and a central conducting post (10) connected to ground terminal (11) of the connector socket is provided at the center of said cavity 20 (9)

20. The cordless electric heating appliance according to claim 18 or 19, wherein said rotatable connector plug is elastically fastened on a lower cover face (26) of the pedestal (23), and the lower cover face (26) is fastened on the bottom (27) of said container (21).

21. The cordless electric heating appliance according to claim 21, wherein a fixed post (28) is provided on said lower cover face (26), said fixed post (28) is sheathed with spring (29), said rotatable connector plug (24) is positioned on said fixed post (28) with a fastener (30), when said rotatable connector plug compresses the spring, there is a clearance (32) between the tip (31) of the fastener (30) and the so connector plug.

_.r

22. The cordless electric heating appliance according to claim 21, wherein a dry burning ejector pin (35) extending to the tail end surface (39) of binding post (1) and being able to jack up side spring contact piece (7) is provided in said binding post (1), a temperature sensing actuator (36) provided on tail end surface (39) of s binding post (1) is against the tip of said dry burning ejector pin (35).

23. The rotatable connector plug according to claim 21, wherein an overtemperature fusing ejector pin (37) extending to tail end surface (39) of binding post (1) and being able to hook up side spring contact piece (7) is provided in said binding post (1), and in the binding post (1), an overtemperature cutting off spring to (38) which can spring up said overtemperature fusing ejector pin (37) is provided thereon.