SU818507A3 - Inductional heating device - Google Patents

Description

(54) INDUCTION HEATING DEVICE

 , . 1 The invention relates to induction heating by industrial currents, frequencies. Known are induction heaters containing a chamber for accommodating a heated material on which an inductor is located and which serves as a heating element, as well as an auxiliary conductor enclosing inductor ij. Known inductors, in about which the outer electrical conductor is made in the form of a cylinder. However, these devices do not allow to reduce dispersion flows and thereby increase the efficiency of the device. The closest to the present invention is an induction heating device comprising a cylindrical heating chamber for accommodating a heated object, an inductor mounted outside of it, made in the form of an annular magnetic circuit wound on it through a winding / insulation and covering it. An element of electrically conductive material electrically connected at the ends with a heating chamber. however, leakage currents occur when using this device. current to the external structure, which are dangerous from the point of view of safety, as well as reduce the efficiency of the device. The purpose of the invention is to increase the efficiency by reducing the dissipation flow. The goal is achieved in that in the known device the specified element of electrically conductive material is made in the form of a closed volume, for example a cylindrical tank. In addition, a closed element made of ferromagnetic material can be additionally placed outside the device, the ends of which are electrically connected to the element of electrically conductive material and the heating chamber. The device is also equipped with an additional driver in the form of tires electrically connected at the ends with an element of electrically conductive material and placed between it and a closed ferromagnetic element, as well as an additional ring magnetic circuit installed between said tires and the element of electrically conductive material. The heating chamber can be made in the form of a tube bundle or in the form of a tank with a bottom; in the latter case, the inductor is installed under the bottom.

FIG. 1 shows an induction heating device, the first embodiment; on league. 2 is a cross-section of the A-Alia of FIG. one; in fig. 3 - device, - longitudinal section; see 4to x1, second embodiment, longitudinal section; Fig. 5 shows the same second embodiment; on league. b a graph presenting the test results of the proposed device; in fig. 7 is a device, the third embodiment.

The device comprises a heating chamber 1, an inductor in the form of a ring 2 consisting of an annular magnetic circuit 3 and a winding 4, and an element 5 enclosing them of electrically conductive material.

The electrical conductor 5 is not made of ribbon-like, but covering the periphery of the heating chamber 1 and the ring 2 for generating a magnetic flux. Of the two streams cf and Cf 2 dispersed in this variant is completely absent, for the reason described below, the stream cp2 dissipates, which can have a harmful effect, and therefore there is no leakage of magnetic flux to the outside.

Suppose that there is a flow (jf going from point A of electrical conductor 5 to the outside and returning inside outflow B, but since the circuit in Fig. 2 is a symmetrical figure with a center of symmetry at its center point, there must exist a flow (f, the same as C), (-as shown) in magnitude and direction. However, the flow and (2 and Cf at point A are equal in magnitude and opposite in direction, therefore joint suivanie both flows is impossible. Consequently, the existence of the flow Cp2 is also impossible. Thus electr cal conductor 5, although not possesses properties of the insulating shield against magnetic flux prevents the occurrence of multiple audio stream and prevents outward leakage flow.

In this connection, the magnetic flux y is presumably remained, which passes around the heating chamber 1 inside the electrical conductor 5, but the red influence of this flux is so small that it can be neglected. In addition, this magnetic flux (p-Mom is easy to calculate with high accuracy.

Thus, an induction heating device (Lig. 1 and 2) has the advantage that its power factor can be increased to a very high degree, moreover, it does not induce interference to the surrounding equipment from the scattering flux.

The proposed device also has the advantage that, since the potential difference observed from the external structures, is only a very small potential difference depending on the degree of potential drop inside the electrical conductor 5 between the two ends of the required section of heat generation chambers 1, there is no danger of the occurrence of such accidents as electric shock to a person.

The said electrical conductor 5 is made of electrically conductive material, such as copper, and preferably of a cylindrical shape, providing the possibility of placing inside it a heating chamber 1 and a ring 2 for generating a magnetic flux. This electrical conductor 5 can be made in a form having a slot-like portion windows for interconnecting the inner and outer sides to facilitate its manufacture and installation.

An element 6 of a ferromagnetic material can be placed outside the device (Fig. 5). This device can also be equipped with a conductor 7 in the form of tires (Fig. 7) and an additional annular magnetic conductor 8. The heating chamber 1 can be made in the form of a bundle of pipes 9 (Fig. 3 or in the form of a tank with 10. In this case, ring 2 Magnetic flux generation can be placed (as shown) near the periphery of the bottom of the tank, although it can be installed around the outside of the central part of the tank.

The heating chamber 1 can be made of at least one metal selected from the group that contain iron, carbon, stainless and heat-resistant steel, etc., whose electrical resistance is greater than that of copper. The annular core 3 can be made by rolling a continuous carbon steel tape into a ring or by assembling rectangular plates from a specified material or by baling carbon ring steel plates. As a material for an annular magnetic circuit 3, instead of a carbon steel sheet, a soft steel sheet can also be used.

Claims (5)

The induction heating device according to the second embodiment (FIG. 5) is designed in such a way that a cylindrical element 6 made of ferromagnetic material located outside the device’s periphery is located outside, both ends of which are electrically connected to the two ends of the desired heat generation section of the heating chamber 1 or to two ends conductor 5 respectively. This device is free of leakage current to external structures connected to it for the reason described below. When an alternating current voltage is applied to the electrical winding 4 between the two ends of the desired heat generation section of the heating chamber 1, a very small potential difference appears in the gap between the outer surface of the electrical conductor 5 and the inner surface of the cylindrical ALL 6 element device by nepiBOMy option. This potential difference can be considered as a source of alternating current, voenikayuschey between the two ends of the cylindrical element 6 with its inner side. The widely known phenomenon is that if a high-frequency current flows to an electrical conductor, it tends to flow concentrating on the surface of the electrical conductor and from the source of energy due to the surface effect. It is well known that in the case when the aforementioned electrical conductor is made of a ferromagnetic material, a significant surface effect can be obtained not only from an electric current of high frequency, but also from an electric current of industrial frequency. Therefore, the flow of alternating current in Cylindrical element 6, arising from this potential difference, is concentrated and very slowly flows along the inner surface of the cylindrical element b and its surroundings. Thus, the potential difference observed outside the cylindrical element 6 is less than the previously mentioned small potential difference by several orders, i.e., ra is zero. Consequently, (.. when bringing into operation such a device, connected to an external structure, having very little electrical resistance, through a pipeline, etc., or directly, there is no leakage current to the said external structure. steel 10B with a wall thickness of 5 mm and a length of 1000 mm, used as a cylindrical element 6, of different voltages E; alternating current with a frequency of 50 Hz, the voltage EO appearing on the outer surface of the steel pipe is measured and the dependence between the applied voltage E and the ratio shown in Fig. 6. As a result, the voltage on the outer surface of the steel pipe is no more than 0.2% of the applied voltage E. Thus, when using this device For example, as a reactor in a chemical plant dealing with combustible materials, there is no danger from a safety point of view, since there is no leakage current to external structures. Induction heating device according to the third Ianthe performing (FIG. 7) is a modification of the second embodiment and is characterized in that the electrical conductor is made in the form of an inner conductor 5 covering the periphery of the heating chamber 1 and the ring 2 for generating a magnetic flux, and the outer conductor 7 located outside said inner conductor 5 and provided with an annular a magnetic conductor 8 located between the inner conductor 5 and the outer conductor 7. Since this device appears very small, as in the device in the first embodiment, the potential difference in romezhutke between the outer surface of the inner conductor 5 and the inner surface of the annular yoke 8, and even smaller compared to its potential difference between the outer surface of the outer pro-. The water source 7 and the inner surface of the cylindrical element 6, the source of alternating current arising in the very cylindrical element 6 between its 1 onts from the inner side, becomes extremely small compared to the current source in the device according to the second embodiment. Therefore, the thickness of the cylindrical element 6 can be reduced despite the fact that the thicker the cylindrical element, the more noticeable is the surface effect, which causes an increase in the above ratio () of stresses. Therefore, this device has the advantage that it is lighter than the device according to the second embodiment, and at the same time, maintaining the same efficiency as the second option, is Economical and convenient for installation. The cylindrical element 6 may be made of a ferromagnetic material selected from the group comprising ductile iron, soft ductile iron for electromagnets, carbon, cast, silicon and chromium-nickel steels, iron-nickel alloy, etc. Invention 1. Induction heating device containing heating a cylindrical chamber for accommodating a heated object, an installed snug and its inductor, made in the form of an annular magnetic circuit with a winding wound on it through the insulation, and encompassing them with an electrically conductive material electrically connected at the ends to the heating chamber, characterized by that, in order to increase efficiency by reducing the dispersion flow, this element of electrically conductive material is made in the form of a closed volume, such as a cylindrical tank. 2, the apparatus according to claim 1, characterized in that a closed element of ferromagnetic material is additionally placed outside, the ends of which are electrically connected to the element of electrically conductive material and the heating chamber. 3. The device according to paragraphs. 1 and 2, characterized in that it is provided with an additional conductor in the form of tires electrically connected at the ends with an element of electrically conductive material - and placed between it and a closed ferromagnetic element, as well as an additional magnetic circuit installed between these tires and an element of electrically conductive material. 4. Device on PP. 1-3, characterized in that the heating chamber is made in the form of a tube bundle: 5. Device on PP. , 1-3, that is, the fact that the heating chamber is made in the form of a tank with dints, and the inductor is installed under the shaft. Sources of information taken into account in the examination 1. USSR author's certificate 73984, cl. H 05 B 5/08, 1949. 1. Author's certificate of the USSR 117388, cl. H.05, B 5/08, 1957. 2. For Japan Japan 28906, cl. H 05 B 5/08, 1972. ./fArW