JPH06236795A - Induction heating plate - Google Patents

Abstract

PURPOSE:To provide an induction heating plate as a heating element capable of easily conducting the induction heating at a constant temperature at low cost. CONSTITUTION:An induction heating plate is constituted in such a manner that an iron plate 1 as a heating body and a plastic plate 2 as an nonmagnetic insulating body are supported in the opposed state by a support leg 3. The support leg 3 is formed from a material having a large thermal expansion coefficient or a highly thermally deformable material. The plate has a form such that the heat conduction from the iron plate can be received to sufficiently expand and contract the length.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating plate as a heating element used for constant temperature control by induction heating.

[0002]

2. Description of the Related Art Conventionally, as a constant temperature control method of this kind in induction heating, the temperature of an object to be heated detected by a temperature sensor is fed back to control the induction heating power by an adjusting device, or the Curie temperature of a magnetic material. It is known to utilize the change in magnetic permeability before and after.

By the way, in the one utilizing the above-mentioned change in magnetic permeability, a magnetic layer whose magnetic permeability changes abruptly at the Curie temperature is provided between the heating element and the coil for generating an alternating magnetic flux interlinking with it. When the temperature of the magnetic layer changes before and after the Curie temperature due to temperature transfer from the heating element,
Utilizing the fact that the magnetic permeability of the magnetic layer suddenly changes so as to increase / decrease the alternating magnetic flux in the direction opposite to the direction in which the heating element temperature changes, the Curie temperature is used as a stable point through the increase / decrease in the alternating magnetic flux. The heating element temperature is set.

[0004]

However, in the above-described constant temperature control by induction heating, in the feedback control system of the induction heating power using the temperature sensor, it may be difficult to attach the temperature sensor and the control may be performed. The system itself is typically complex and expensive in its construction. Further, as described above, the one utilizing the change in magnetic permeability before and after the Curie temperature is:
A sudden change in magnetic permeability is required to increase the temperature setting accuracy,
Therefore, an expensive material such as ferrite is required as a required magnetic material, and the heating element as a whole is inevitably expensive.

In view of the above, it is an object of the present invention to provide an induction heating plate as a heating element that can inexpensively and easily perform induction heating at a constant temperature without using a complicated temperature control system.

[0006]

In order to achieve the above object, the induction heating plate of the present invention has a magnetic metal plate and a non-magnetic insulating plate facing each other by supporting legs arranged at respective predetermined portions. Is fixedly connected, and the supporting leg is formed of a material having a large coefficient of thermal expansion, and has a shape such that its length is changed according to the heating state, and the heating state of the metal plate for supplying heat to the supporting leg. The metal plate and the insulating plate, which are connected by the support leg, are changed in mutual distance in accordance with the above, or the support leg is made of a material having a large coefficient of thermal expansion, instead of being formed of heat. It is assumed that the support leg is formed of a deformable bimetal, and the support leg is also formed of a shape-memory alloy that thermally deforms. Further, regarding the connection between the metal plate and the insulating plate by the support leg, both of them are connected together. Instead of constant connection, only one of the two is fixedly connected, and a plurality of protrusions are provided on the surface of the metal plate on the side facing the insulating plate, and each protrusion is paired with the protrusion. A ferromagnetic material block forming a magnetic path is attached to the insulating plate.

[0007]

In general, the induction heating utilizes the heat generated by the resistance loss generated by the induced current generated in the conductor placed in the alternating magnetic field in the resistance component of the conduction path. Here, the induced current is proportional to the induced voltage in the conduction path, the induced voltage is proportional to the amount of alternating magnetic flux interlinking with the conductor and its temporal change rate, and the amount of magnetic flux is the magnetic resistance in the passage. Is inversely proportional to the magnetomotive force, and the magnetic resistance is proportional to the length of the magnetic flux passage and inversely proportional to its magnetic permeability.

That is, the induced current decreases as the length of the magnetic flux passage increases. Therefore, the magnetic resistance is made variable by changing the distance between the magnetic metal plate as the conductor and the energizing coil for generating the interlinking magnetic flux to the metal plate according to the heating temperature of the metal plate. Thereby, it becomes possible to make the heating temperature of the metal plate constant. According to the present invention, a magnetic metal plate and a non-magnetic insulating plate are supported in a face-to-face relationship with each other by supporting legs arranged at respective predetermined portions, and the distance between the two is maintained, and the length of the supporting leg is long. Heats an induction heating plate formed so as to make a required expansion / contraction change depending on its own temperature by heating the coil installed on the insulating plate side of the heating plate with an alternating current, The heating temperature of the metal plate is made constant by utilizing the expansion and contraction of the distance between the insulating plates, and the supporting leg is formed of a material having a large coefficient of thermal expansion, or a bimetal or a shape memory alloy having a large thermal deformation. It is a thing.

Further, regarding the connection of both the metal plate and the insulating plate by the supporting legs in the induction heating plate as described above, both of them are fixedly connected, or smooth heat transfer from the metal plate to the supporting leg is performed. While making a fixed connection with only one of the supporting leg and the metal plate or the insulating plate, the other one is made detachable to facilitate disassembly for cleaning or cleaning. In order to equalize the distribution of the magnetic path between the coil and the metal plate, a plurality of protrusions are provided on the surface of the metal plate on the side facing the insulating plate, and a magnetic path is formed in pairs with each protrusion. The ferromagnetic material block to be formed is attached to the insulating plate.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to a perspective view or a side view of an induction heating plate shown in FIGS. In addition, in each of the drawings, the same reference numeral is given to the component having the same function. FIG. 1 shows a first embodiment of the present invention. FIG. 1A is a perspective view of an induction heating plate, and FIGS. 1B and 1C are side views thereof.

First, in FIG. 1A, 1 is an iron plate as a heating element, 2 is a plastic plate as a non-magnetic insulator which forms the basis of the overall structure of the induction heating plate, and 3 is a material having a large coefficient of thermal expansion. A support leg which is formed of and which expands and contracts due to heat transfer from the iron plate, 3a is an upper fixing portion of the support leg that connects the support leg and the iron plate, and 3b is a lower part of the support leg that connects the support leg and the plastic plate It is a side fixing part. It should be noted that the supporting legs are provided in a sufficient number to support the iron plate on which a predetermined heavy object is loaded.

Next, as shown in FIG. 1B, the iron plate 1 is at a higher temperature than its steady state and each of the supporting legs is extended so that the distance between the iron plate and the plastic plate becomes wider than in the steady state. It shows the state. Further, FIG. 1C shows a state in which the iron plate 1 is at a temperature lower than that in the steady state, and the supporting legs are contracted so that the distance between the iron plate and the plastic plate becomes narrower than in the steady state. is there.

Further, FIG. 2 shows a state in which the induction heating plate is arranged above the induction coil 4 for generating a magnetic flux interlinking with the iron plate 1 by passing an alternating current, and the magnetic field lines 10 formed by the coil 4 are shown. This is a representative simulation including the passing route with a chain line. Now, with the spacing between the induction coil 4 and the plastic plate 2 fixed, if the iron plate 1 becomes a higher temperature than its steady state and the space between both plates becomes wider than in its steady state, the iron plate 1 is linked with the iron plate. The generated magnetic flux is reduced from the steady state amount, and the heating amount to the iron plate is also reduced, so that the distance between the two plates is gradually reduced toward the steady value. On the contrary, if the iron plate becomes a temperature lower than its steady state and the distance between both plates becomes narrower than that in its steady state, the iron plate interlinkage magnetic flux increases more than its steady state amount to the iron plate. The amount of heating of the plate also increases, and the distance between the plates gradually extends toward its steady value.

That is, the temperature of the iron plate is increased in accordance with the distance between the iron plate and the plastic plate by the adoption of the above-described support leg that produces a thermal response, and the magnetomotive force is proportional to the value of the alternating current supplied to the induction coil. Will be fixed to a steady value defined by. Next, FIG. 3 shows a second embodiment of the present invention, in which the supporting leg 3 in the induction heating plate shown in FIG. 1 is formed of bimetal to form the supporting leg 5, and the upper and lower fixing portions thereof are respectively formed. 5a and 5b, and the change in the plate-to-plate spacing due to the thermal response is the same as in the case of FIG.

FIG. 4 shows a third embodiment of the present invention, in which the support leg 3 in the induction heating plate shown in FIG. 1 is formed of a shape memory alloy, and this is used as the support leg 6 and the upper and lower parts thereof are fixed. Parts 6a and 6b are provided, respectively, and the support leg 6 extends based on the stored temperature, so that the change in the plate-to-plate spacing due to the thermal response is the same as in the case of FIG. .

FIG. 5 shows a fourth embodiment of the present invention, which can be commonly applied to the induction heating plates shown in FIGS. 1 to 4, and includes the metal plate and the plastic plate. With regard to the connection, the connection with the plastic plate in the lower part of the supporting leg is not fixed but detachable, and the disassembly for cleaning or cleaning is facilitated. Further, FIG. 6 shows a fifth embodiment of the present invention, and FIGS.
It can be commonly applied to the induction heating plate shown in Fig. 1 and has a plurality of protrusions provided on the surface of the iron plate facing the plastic plate and forms a magnetic path by forming a pair with each protrusion. A ferrite core 8 is attached to the plastic plate as a magnetic material block to equalize the distribution of the magnetic paths between the induction coil and the iron plate.

[0017]

According to the present invention, the induction heating plate is made of a magnetic metal plate such as an iron plate and a non-magnetic insulating plate such as plastic in a state of facing each other by supporting legs arranged at respective predetermined portions. By connecting and forming the supporting leg with a material having a large thermal expansion coefficient or a material having a large thermal deformation, the metal plate and the insulating plate are automatically stretched in accordance with the temperature of the metal plate and the metal is formed. The plate temperature can be kept constant,
Induction heating at a constant temperature can be realized by an inexpensive and simple induction heating plate as a heating element, without using a complicated temperature control system.

[Brief description of drawings]

1 shows a first embodiment of the present invention, FIG. 1 (a) is a perspective view thereof, and FIG. 1 (b) and FIG. 1 (c) are side views thereof, respectively.

FIG. 2 is a side view of an induction heating plate arranged on an induction coil.

FIG. 3 is a side view of an induction heating plate showing a second embodiment of the present invention.

FIG. 4 is a side view of an induction heating plate showing a third embodiment of the present invention.

FIG. 5 is a side view of an induction heating plate showing a fourth embodiment of the present invention.

FIG. 6 is a side view of an induction heating plate showing a fifth embodiment of the present invention.

[Explanation of symbols]

 1 Iron plate 2 Plastic plate 3 Support leg 3a Support leg upper fixed part 3b Support leg lower fixed part 4 Induction coil 5 Support leg 6 Support leg 7 Iron plate 8 Ferrite core 10 Magnetic field line

Claims (5)

[Claims] 1. A magnetic metal plate and a non-magnetic insulating plate are fixedly connected in a face-to-face relationship with each other by supporting legs arranged at respective predetermined portions, and the supporting legs are made of a material having a large thermal expansion coefficient. The shape of the metal plate is such that its length is changed according to its heating state, and the metal plate and the insulating plate are connected to each other according to the heating state of the metal plate for supplying heat to the supporting leg. A plate for induction heating, characterized in that it is configured so as to change the interval. 2. The induction heating plate according to claim 1, wherein the supporting leg is formed of a bimetal that is thermally deformed, instead of forming the supporting leg of a material having a large thermal expansion coefficient. Induction heating plate. 3. The induction heating plate according to claim 1, wherein the support leg is formed of a shape-memory alloy that thermally deforms, instead of forming the support leg by a material having a large thermal expansion coefficient. Characteristic induction heating plate. 4. The induction heating plate according to claim 1, wherein the metal plate and the insulating plate are both connected by the supporting leg,
An induction heating plate, characterized in that instead of fixedly connecting both of them, only one of them is fixedly connected. 5. The induction heating plate according to claim 1, wherein a plurality of protrusions are provided on the surface of the metal plate on the side facing the insulating plate, and a magnetic path is formed by forming a pair with each protrusion. A plate for induction heating, characterized in that a ferromagnetic material block to be formed is attached to the insulating plate.