CN2162755Y

CN2162755Y - Screened field-discharge heating apparatus

Info

Publication number: CN2162755Y
Application number: CN 93222803
Authority: CN
Inventors: 潘雨力
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-08-25
Filing date: 1993-08-25
Publication date: 1994-04-20
Anticipated expiration: 2003-08-25

Abstract

The utility model relates to a screened field-discharge heating apparatus such as electric blankets, electric heat belts, electric heat clothes, etc., which can eliminate harm from low frequency field-discharge to a human body. The utility model is characterized in that a heating element is mainly composed of two insulation layers and electric heat wires; a conducting layer is arranged between the two insulation layers; the conducting layer is connected with one end of the electric heat wire, which forms a circuit; the conducting layer and the other end of the electric heat wire are respectively connected with the null line and the live line of a power source. The other configuration of the screened field-discharge heating apparatus is that a screen is added out of the outer insulation layer and the screen is connected with the ground. The utility model has the advantage that the screened field-discharge heating apparatus can effectively screen low frequency electromagnetic field which is especially hard to screen by other means, and has the ability of preventing electric shock and fire.

Description

Screened field-discharge heating apparatus

The utility model relates to electric heating apparatus such as the electric blanket that can eliminate power frequency electromagnetic field harm, ribbon heater, electric heating clothes.

Scientific research shows: often be in that the health to the people is extremely harmful in the low frequency electromagnetic field of certain intensity.Adopting the heating wire that a layer insulating is only arranged is that the electric blanket and the similar electric heating apparatus of heater all exists electromagnetic field around it when work, therefore very big to its people's of frequent use health hazard.Chinese patent 91207565.1 has been announced the technology of a kind of " low electromagnetic field safe electric heating apparatus " by name, and it adopts screen that alternating electric field is masked, and adopts two-wire or the parallel close-up of biobelt, thus the opposite offset magnetic field of current direction in two line or belts.This structure can shield electric field preferably, but it is just exactly so to magnetic field, by the Theory of Electromagnetic Field analysis as can be known: this structure only just can be cancelled in magnetic field at a distance from two-wire, and reach when field intensity is than single line on the sealing bigger in the crack of two wires, lean on the two wires to such an extent that extremely closely can reduce this influence, but the difficulty that realizes on the technology also increases, and therefore this structure is difficult for realizing, magnetic field can not be shielded well.

The purpose of this utility model just provides a kind of power frequency electric field can being masked, the electric calorifie installation that power frequency magnetic field can be masked well again, and it can overcome the harm to human body of electric blanket and similar electric heating apparatus medium and low frequency electromagnetic field effectively.

The utility model is to be realized by following technical scheme: be provided with one deck conductive layer (3) in the middle of in the middle of the double hyer insulation layer (2) (4) of heating wire (1), conductive layer (3) constitutes coaxial configuration with heating wire (1), link to each other with conductive layer (3) at one end heating wire (1) and to constitute the loop, link to each other with the zero line of power supply at other end conductive layer (3), the line and heating wire (1) is started to exchange fire, so just realized the omnidirectional structure in the shielding theory, this structure can not produce electromagnetism in the space and raise.

For avoid live wire identification loaded down with trivial details, when avoiding the zero-power line broken string or zero line above earth potential when raising, conductive layer (3) is alternating electric field increase suddenly on every side, also can adopt another program, that is exactly to add a screen (5) outside above-mentioned structure again, and screen (5) is to encase the cylindrical shape of interior lines body or banded structure or planar structure to clamp the interior lines body.This screen (5) ground connection, thus realization is to the good shielding of electromagnetic field.

Be further described below in conjunction with accompanying drawing:

Fig. 1 has the partial structurtes schematic diagram of the electric heating element of coaxial configuration;

Fig. 2 has the partial structurtes schematic diagram of the electric heating element of double shield layer;

Fig. 3 has the loose routing figure of the electric heating element of coaxial configuration;

Fig. 4 has the loose routing figure of the electric heating element of double shield layer;

Fig. 5 has current trend schematic diagram in the electric heating element of coaxial configuration;

Fig. 6 has electromagnetic field distribution schematic diagram in the electric heating element of coaxial configuration;

The loose routing figure of electric heating element when Fig. 7 connects low-voltage dc power supply;

The loose routing figure of electric heating element when Fig. 8 connects low-voltage alternating current power supply;

Number among the figure: 1, heating wire, 2, insulating barrier, 3, conductive layer, 4, insulating barrier, 5, screen, E, power line, the B magnetic line of force, Ne neon tube, F fuse.

With reference to shown in Figure 5, adopt this structure to flow through the total current Ii(t of heating wire (1) at any one time) with flow through the total current Io(t of conductive layer (3)) all be opposite sign but equal magnitude, by the quasi-static equation of Theory of Electromagnetic Field and the symmetry of this coaxial configuration relational expression is arranged:

∮

（

.t）. ＝2πR.B（R.t）＝μ（Ii（t）＋Io（t））

(wherein R is for investigating the distance of point to heating wire (1), and μ is the permeability of conductive layer (3)).

Outside conductive layer (3), Ii(t is arranged)+Io(t)=0, so magnetic field B (R.t)=0, hence one can see that: adopt this structure magnetic field can be shielded fully.

With reference to shown in Figure 3, because conductive layer (3) adopts the very low conductor of resistivity, and connect the zero line of power supply again, therefore phase line voltage major part is fallen on heating wire, and that conductive layer (3) is gone up pressure drop is very little, and conductive layer (3) is gone up current potential also just near the current potential of zero line, and zero-power line above earth potential very low (being generally about 1 volt), therefore conductive layer (3) above earth potential is also very low, and the electric field around it is also extremely low, so just eliminated live wire on every side alternating electric field to the harm of human body.Electromagnetic field distributes as shown in Figure 6 in the utility model structure, power line radially, the magnetic line of force is around heating wire (1).

With reference to loose routing figure shown in Figure 3, wherein adopted the live wire identification circuit, to guarantee conductive layer connecting to neutral line, the live wire identification circuit also can adopt sound circuit, its end can be connected on the heating wire, also can be connected on the conductive layer (3), the other end is connected on the palp electrode of hand or on the ground wire, also can be communicated with ground wire when detecting by a push-button switch.This live wire identification circuit can be contained in the attaching plug of electric heating apparatus or in the power switch box of electric heating apparatus so that use.Conductive layer (3) connecting to neutral line also makes us realize the circuit zero connection protection, and (3) can not get an electric shock yet even the people runs into exposed conductive layer accidentally, and can not cause fire when the same for a certain reason conductive layer of heating wire (1) (3) partial short-circuit yet.

In the partial structurtes figure of Fig. 1, electric heating element shown in Figure 2, insulating barrier (2) can adopt a kind of insulating material, also can adopt two kinds of material superpositions, can prevent from when adopting two kinds of different materials superpositions to embed insulating barrier (2) after heating wire (1) long-term work, make heating wire (1) and conductive layer (3) constantly approaching until short circuit in the part; Conductive layer (3) can adopt technologies such as metal knitted net, electroplated film disk or stranded conductor coiling to make; Screen (5) also can adopt the single cord coiling or makes with conductive plastics except the manufacture craft that can adopt conductive layer (3), and screen (5) is outer also can to add a layer insulating again.Heating wire is single, also can with thin resistive conductor on the heatproof insulated wire so that the enhancing pull resistance.

Advantage of the present utility model is:

(1) low frequency magnetic field that can effectively low frequency electromagnetic field, especially method for distinguishing are difficult to shield masks well, and practice shows that this structure can realize 80 decibels decay to low frequency electromagnetic field.

(2) because conductive layer (3) connecting to neutral line has formed zero connection protection, electric heating apparatus protection against electric shock and fireproof ability have been improved.

(3) owing to need not also working effectively by special again earth connection, easy to use.

(4) structure of Cai Yonging is easy to realize on technology.

Several cabling scenario of the present utility model is shown in Fig. 3,4,5,6,7,8, and Fig. 7,8 is respectively and connects low-voltage direct, the situation of AC power.

The optimum implementation of electric heating element is: adopt the wiring of Fig. 3, the insulating barrier (2) between heating wire (1) and the conductive layer (3) adopts two kinds of material superpositions, and conductive layer (3) adopts metal knitted net, its outer layer insulating (4) that wraps again.

Claims

1, a kind of protected type electric heating apparatus that disappears mainly is made of the heating wire with dielectric layers, it is characterized in that: be provided with conductive layer between the dielectric layers of heating wire, this conductive layer at one end links to each other with heating wire and constitutes the loop.

2, a protected type electric heating apparatus that disappears according to claim 1 is characterized in that adding a screen outside described outer field insulating barrier.

3, a protected type electric heating apparatus that disappears according to claim 1 is characterized in that the other end of conductive layer and heating wire connects the zero line and the live wire of power supply respectively.

4, a protected type electric heating apparatus that disappears according to claim 1 is characterized in that being provided with in the circuit live wire identification circuit, and this identification circuit is contained in the attaching plug of electric heating apparatus or in the mains switch of electric heating apparatus.

5, as protected type electric heating apparatus as described in the claim 2, it is characterized in that screen can be the cylindrical shape that encases the inner wire body, also can be planar shaped clamp inner wire body and this shielding layer grounding.

6, protected type electric heating apparatus as claimed in claim 1 or 2 is characterized in that insulating barrier is made of one or both material superpositions.