JP6832488B2 - Heating coil and rice cooker with it - Google Patents

Description

The present disclosure relates to a heating coil used in an induction heating cooker and a rice cooker including the heating coil.

Conventionally, in the field of induction heating cookers, in order to reduce the weight of the heating coil and the loss in the heating coil, a wire having a fusion layer is further provided on an insulating layer provided on the surface of a conductor such as a copper wire. The heating coil used has been proposed (see, for example, Patent Document 1).

FIG. 6A is a cross-sectional view of the strands of the conventional heating coil 200 described in Patent Document 1. FIG. 6B is a cross-sectional view of the heating coil 200.

As shown in FIGS. 6A and 6B, the heating coil 200 is composed of a wire 201. The wire 201 includes a long and thin conductor 202, an insulating layer 203, and a fusion layer 204. The long and thin conductor 202 is made of a copper wire or the like. The insulating layer 203 is provided on the surface of the conductor 202. The fused layer 204 is provided on the surface of the insulating layer 203.

As shown in FIG. 6B, a plurality of strands 201 are twisted together to form an assembly wire 205. After winding the collecting wire 205 in a spiral shape, the collecting wire 205 is fused by the fusion layer 204 to form a disk-shaped heating coil 200.

In the field of high frequency electric wires, electric wires for suppressing AC resistance, heat generation and power consumption have been proposed. This electric wire has an elongated central conductor, a coating layer provided on the surface of the central conductor, and an insulating layer provided on the surface of the coating layer. The coating layer is formed of a metal different from the metal constituting the central conductor (see, for example, Patent Document 2).

FIG. 7 is a cross-sectional view of the conventional high frequency electric wire 300 described in Patent Document 2. As shown in FIG. 7, the high-frequency electric wire 300 includes a central conductor 301, a coating layer 303, and an intermetallic compound layer 302.

The center conductor 301 is made of aluminum or an aluminum alloy. The coating layer 303 is made of copper and is provided on the surface of the central conductor 301. The intermetallic compound layer 302 is formed between the central conductor 301 and the coating layer 303 so that the composition gradually changes from the central conductor 301 to the coating layer 303. The intermetallic compound layer 302 has a larger volume resistivity than the coating layer 303.

In order to suppress heat generation and power consumption of the heating coil, the present inventors have studied the adoption of the conventional high-frequency electric wire as a conductor of the wires constituting the conventional heating coil.

JP-A-59-08618A Japanese Patent No. 5266340

However, simply combining the above-mentioned conventional high-frequency electric wire with the wire constituting the above-mentioned conventional heating coil is not sufficient from the viewpoint of the reliability of the heating coil.

For example, when the conventional heating coil described in Patent Document 1 is combined with the conventional high-frequency electric wire described in Patent Document 2, the strands constituting the assembly wire of the heating coil are fused with the central conductor, the coating layer, the insulating layer, and the wire. Including layers. The center conductor is made of aluminum or an aluminum alloy. The coating layer is made of copper and is provided on the surface of the central conductor. The insulating layer is provided on the surface of the coating layer. The fusion layer is provided on the surface of the insulating layer.

The heating coil is formed by twisting a plurality of the above-mentioned strands and fusing the spirally wound aggregate wires. In this configuration, since the wire coating layer is formed of a metal different from the metal constituting the wire center conductor, the properties such as ductility differ between the wire center conductor and the wire coating layer. .. In general, aluminum is inferior to copper in terms of ductility, so that the central conductor of the wire is inferior to the coating layer of the wire in terms of ductility.

On the other hand, if all the strands constituting the assembly line have a fusion layer, the assembly line becomes too hard. Therefore, in the above-mentioned assembly wire, there is a possibility that the heating coil may be broken in the manufacturing process.

The present disclosure solves the above-mentioned conventional problems, and forms a heating coil without disconnection in the manufacturing process even if the conductor contains a metal having a ductility inferior to that of copper. By providing this heating coil, it is an object of the present invention to provide a highly reliable rice cooker.

In order to solve the above problems, one aspect of the present disclosure is a heating coil including a winding having a first core wire and a second core wire. The first core wire includes an elongated first conductor and a first insulating layer provided on the surface of the first conductor. The second core wire includes an elongated second conductor, a second insulating layer provided on the surface of the second conductor, and a fusion layer provided on the surface of the second insulating layer.

Another aspect of the present disclosure is a rice cooker provided with the heating coil.

According to the heating coil of the above aspect, it is possible to prevent disconnection of the winding in the manufacturing process. By providing the above heating coil, a highly reliable rice cooker can be provided.

FIG. 1 is an overall perspective view showing the appearance of the heating coil according to the embodiment of the present disclosure. FIG. 2 is a perspective view of the winding of the heating coil according to the embodiment. FIG. 3A is a cross-sectional view of the first core wire constituting the winding of the heating coil according to the embodiment. FIG. 3B is a cross-sectional view of the second core wire constituting the winding of the heating coil according to the embodiment. FIG. 4A is a diagram showing a state in which the winding of the heating coil according to the embodiment is composed of only the second core wire and the winding is deformed. FIG. 4B is a diagram showing a state in which the winding of the heating coil according to the embodiment is composed of the first core wire and the second core wire, and the winding is deformed. FIG. 5 is a cross-sectional view of the rice cooker according to the embodiment of the present disclosure. FIG. 6A is a cross-sectional view of the strands of the conventional heating coil. FIG. 6B is a cross-sectional view of a conventional heating coil. FIG. 7 is a cross-sectional view of a conventional high-frequency electric wire.

The first aspect of the present disclosure is a heating coil including a winding having a first core wire and a second core wire. The first core wire includes an elongated first conductor and a first insulating layer provided on the surface of the first conductor. The second core wire includes an elongated second conductor, a second insulating layer provided on the surface of the second conductor, and a fusion layer provided on the surface of the second insulating layer. According to this aspect, it is possible to prevent disconnection of the winding in the manufacturing process of the heating coil.

According to the second aspect of the present disclosure, in the first aspect, the number of the first core wires is 30% to 50% of the total number of the first core wires and the number of the second core wires. According to this aspect, it is possible to prevent disconnection of the winding in the manufacturing process of the heating coil.

According to the third aspect of the present disclosure, in the first or second aspect, the first conductor is provided on the surface of the first central conductor provided at the center of the first conductor and the surface of the first central conductor. It contains a first coating layer and has a diameter of 0.1 to 0.3 mm. The first coating layer has a volume resistance smaller than that of the first center conductor, and has a cross-sectional area of 10 to 20% of the cross-sectional area of the first conductor.

According to this aspect, the resistance of the heating coil when a high frequency current flows can be reduced, and as a result, the loss in the heating coil can be reduced.

According to the fourth aspect of the present disclosure, in any of the first to third aspects, the second conductor is placed on the second center conductor provided at the center of the second conductor and on the surface of the second center conductor. It includes a second coating layer provided and has a diameter of 0.1 to 0.3 mm. The second coating layer has a volume resistance smaller than that of the second center conductor and has a cross-sectional area of 10 to 20% of the cross-sectional area of the second conductor.

According to this aspect, the resistance of the heating coil when a high frequency current flows can be reduced, and as a result, the loss in the heating coil can be reduced.

According to the fifth aspect of the present disclosure, in any of the first to fourth aspects, the fused layer has a lower melting point than the first insulating layer and the second insulating layer.

According to this aspect, the winding can be fused by the fusion layer without damaging the first insulation layer and the second insulation layer.

A sixth aspect of the present disclosure is a rice cooker provided with a heating coil according to any one of the first to fifth aspects. According to this aspect, since a heating coil without disconnection is used in the manufacturing process, a highly reliable rice cooker can be provided.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or corresponding parts may be designated by the same reference numerals, and duplicate description may be omitted.

[Structure of heating coil]
The heating coil 1 according to the embodiment of the present disclosure will be described with reference to FIGS. 1 to 4B. As will be described later, the induction heating cooker according to the present embodiment is the rice cooker 100 (see FIG. 5).

FIG. 1 is a perspective view showing the appearance of the heating coil 1. FIG. 2 is a perspective view of the winding wire 2 constituting the heating coil 1. 3A and 3B are cross-sectional views showing the core wire 3 and the core wire 6 constituting the winding wire 2, respectively.

As shown in FIG. 1, the heating coil 1 is formed by winding one elongated winding 2 in a spiral shape. As shown in FIG. 2, the winding 2 is formed by twisting an aggregate wire in which a predetermined number of core wires 3 and a predetermined number of core wires 6 are arranged at predetermined intervals.

As shown in FIG. 3A, the core wire 3 has an elongated conductor 4 and an insulating layer 5 provided on the surface of the conductor 4. The conductor 4 includes a central conductor 4a provided at the center of the conductor 4 and a coating layer 4b provided on the surface of the conductor 4.

As shown in FIG. 3B, the core wire 6 has an elongated conductor 7, an insulating layer 8 provided on the surface of the conductor 7, and a fusion layer 9 provided on the surface of the insulating layer 8. The conductor 7 includes a central conductor 7a provided at the center of the conductor 7 and a coating layer 7b provided on the surface of the conductor 7.

When the collective wire obtained by twisting the core wires 3 and 6 is wound around a jig and a high frequency current is supplied to the collective wire, the collective wire generates heat. This heat generation melts the fused layer 9 of the core wire 6. As a result, the core wire 3 and the core wire 6 are fused to form the winding 2.

The core wire 3 corresponds to the first core wire, and the core wire 6 corresponds to the second core wire. The conductor 4 corresponds to the first conductor, and the conductor 7 corresponds to the second conductor. The insulating layer 5 corresponds to the first insulating layer, and the insulating layer 8 corresponds to the second insulating layer. The center conductor 4a corresponds to the first center conductor, and the center conductor 7a corresponds to the second center conductor. The coating layer 4b corresponds to the first coating layer, and the coating layer 7b corresponds to the second coating layer.

In an induction heating cooker, when a high frequency current of 20 to 100 kHz is supplied to the heating coil, the current concentrates on the surface of the conductor due to the skin effect. Therefore, when the conductor has a central conductor and a coating layer provided on the surface of the central conductor, the resistance value of the coating layer which is the surface portion of the conductor is reduced in order to suppress heat generation and power consumption of the heating coil. There is a need.

In order to reduce the burden on the user, it is preferable that the weight of portable home appliances such as rice cookers is light. In the present embodiment, the central conductors 4a and 7a are made of a material having a small volume resistance value and a light weight, aluminum or a metal containing aluminum.

The coating layers 4b and 7b are preferably made of a material having a smaller volume resistance value than aluminum or an aluminum alloy, for example, a metal such as gold, silver, or copper. In the present embodiment, the coating layers 4b and 7b are made of copper.

In the above configuration, the diameters of the conductors 4 and 7, the ratio of the central conductor 4a to the coating layer 4b, the ratio of the center conductor 7a to the coating layer 7b, and the like are set according to the use of the heating coil 1.

As described above, in the heating coil 1 through which a high frequency current of 20 to 100 kHz flows, the diameters of the conductors 4 and 7 are preferably set to 0.1 to 0.3 mm, and more preferably set to 0.25 mm. ..

The cross-sectional area of the coating layer 4b is preferably set to 10 to 20% of the cross-sectional area of the conductor 4 having the above diameter, and more preferably set to 15%. The conductor 7 is the same as the conductor 4.

With this configuration, the resistance of the heating coil 1 when a high-frequency current flows through the heating coil 1 can be reduced, and the loss in the heating coil 1 can be reduced.

The insulating layers 5 and 8 are preferably made of a type F or type H insulating material specified by the Electrical Appliance and Material Safety Law. With this configuration, the conductors 4 and 7 can be reliably insulated by the insulating layers 5 and 8, respectively.

In the present embodiment, the fusion layer 9 is preferably made of a thermoplastic material having a melting point lower than that of the insulating layers 5 and 8 and higher than the temperature of the heating coil 1 during operation, for example, a polyamide resin. With this configuration, the fused layer 9 melts at a temperature lower than the melting points of the insulating layers 5 and 8.

Therefore, in order to bundle the core wire 3 and the core wire 6 to form the winding 2 of the heating coil 1, when the core wire 3 and the core wire 6 are fused, the insulating layers 5 and 8 are not damaged and are insulated. The layers 5 and 8 can reliably insulate the conductors 4 and 7, respectively.

Hereinafter, the features of the heating coil 1 according to the present embodiment will be described.

As described above, the winding 2 of the heating coil 1 is formed by twisting and fusing a plurality of core wires 3 that do not include the fusion layer 9 and a plurality of core wires 6 that include the fusion layer 9. ..

Comparing the case where the winding 2 is composed of only the core wire 6 having the fusion layer 9 and the case where the winding 2 is composed of the core wire 3 having no fusion layer 9, the winding 2 is The former is more firmly fixed than the latter. Therefore, the change in the cross-sectional shape of the winding 2 when the winding 2 is curved is smaller in the former than in the latter. Therefore, the core wires 3 and 6 located outside the curved winding 2 are stretched more in the former than in the latter.

In the present embodiment, the conductor 4 of the core wire 3 includes a central conductor 4a made of aluminum or an aluminum alloy and a coating layer 4b made of copper. The conductor 7 of the core wire 6 includes a central conductor 7a made of aluminum or an aluminum alloy, and a coating layer 7b made of copper. Therefore, if the winding 2 is greatly stretched, the central conductors 4a and 7a, which are inferior in malleability, may be disconnected.

In the present embodiment, in order to prevent disconnection of the central conductors 4a and 7a, the winding 2 is configured by including not only the core wire 6 having the fusion layer 9 but also the core wire 3 having no fusion layer 9. According to this embodiment, the bonding force between the core wires can be reduced, and the winding 2 can be formed softer. As a result, it is possible to prevent disconnection of the winding 2 in the manufacturing process.

Hereinafter, a more specific description will be given. The elongation rate of the curved winding 2 is determined by the bending radius and the distance from the neutral surface to the outer circumference of the curved winding 2. The larger the elongation rate of the winding 2, the greater the elongation of the winding 2, and the easier it is for the wire to break.

FIG. 4A is a diagram showing a state in which the winding wire 2 including only the core wire 6 is curved. As shown in FIG. 4A, the diameter of the winding 2 is D0, the bending radius of the winding 2 is R1, the distance from the neutral surface F of the winding 2 to the outer circumference of the winding 2 is L1, and the elongation rate of the winding 2. Is H1, and the elongation rate H1 is expressed by the equation (1).

H1 = L1 / R1 (1)
In the winding 2 having only the core wire 6, since the winding 2 is formed more rigidly, when the winding 2 is curved with a bending radius R1, the cross-sectional shape of the winding 2 hardly changes. Therefore, in this case, the distance L1 from the neutral surface F to the outer circumference of the winding 2 is represented by the equation (2).

L1 = D0 / 2 (2)
FIG. 4B is a diagram showing a state in which the winding 2 including the core wires 3 and 6 is curved. As shown in FIG. 4B, the diameter of the winding 2 is D0, the bending radius of the winding 2 is R1, the distance from the neutral surface F of the winding 2 to the outer circumference of the winding 2 is L2, and the elongation rate of the winding 2 is Is H2, and the elongation rate H2 is expressed by the equation (3).

H2 = L2 / R1 (3)
In the case shown in FIG. 4B, the coupling force between the core wires is weaker and the winding 2 is softer than in the case shown in FIG. 4A. Therefore, when the winding 2 is curved, the cross-sectional shape of the winding 2 becomes elliptical as shown in FIG. 4B. At this time, assuming that the major axis and the minor axis of the winding 2 having a cross-sectional shape are D1 and D2, respectively, the distance L2 from the neutral surface F to the outer circumference of the winding 2 is half of the minor axis D2.

Since the minor axis D2 is smaller than the diameter D0, the elongation rate H2 of the winding wire 2 in the case shown in FIG. 4B is smaller than the elongation rate H1 of the winding wire 2 in the case shown in FIG. 4A.

Therefore, when the heating coil 1 is formed by using the winding 2 in the case shown in FIG. 4B, the winding 2 is formed as compared with the case where the heating coil 1 is formed by using the winding 2 in the case shown in FIG. 4A. Not greatly stretched. As a result, it is possible to prevent disconnection of the winding 2 in the manufacturing process.

[Ratio of core wire 6 in winding 2]
Hereinafter, the heating coil 1 according to the present embodiment will be described in more detail.

As the proportion of the core wire 6 in the winding 2 increases, the amount of the fused layer 9 contained in the winding 2 increases, and the winding 2 is more firmly fixed. As described above, as the winding 2 is firmly fixed, there is a high possibility that the winding 2 will be broken when the heating coil 1 is formed.

On the other hand, when the ratio of the core wire 6 in the winding wire 2 decreases, the amount of the fused layer 9 contained in the winding wire 2 decreases, the bonding force between the core wires decreases, and the winding wire 2 becomes soft. Therefore, the possibility that the winding 2 is broken when the heating coil 1 is formed is low. However, if the coupling force between the core wires is too low, the core wires 3 and 6 are not firmly fixed, and the strength of the heating coil 1 is lowered.

Therefore, in order to improve the strength of the heating coil 1 and prevent the winding 2 from being broken, it is necessary to configure the winding 2 with the core wires 3 and 6 having an appropriate ratio.

Hereinafter, the experimental results regarding an appropriate ratio of the core wires 6 included in the winding 2 will be described.

In this experiment, a heating coil 1 formed of windings 2 having core wires 3 and 6 having the following configurations is used. The core wire 3 has a conductor 4 having a diameter of 0.25 mm and an insulating layer 5 made of an insulating material of type F. The conductor 4 includes a central conductor 4a made of aluminum or an aluminum alloy, and a coating layer 4b made of copper.

The core wire 6 has a conductor 7 having a diameter of 0.25 mm, an insulating layer 8 made of an insulating material of type F, and a fusion layer 9 made of a polyamide resin. The conductor 7 includes a central conductor 7a made of aluminum or an aluminum alloy, and a coating layer 7b made of copper.

In this experiment, the winding 2 in which the ratio of the core wire 6 to the total number of the core wires 3 and 6 is 25% to 55% is bent and stretched 90 degrees a predetermined number of times (for example, a few times). It was confirmed whether or not the core wire of the winding wire 2 was peeled off and whether or not the winding wire 2 was broken.

Table 1 shows the experimental results. Here, it is assumed that the winding 2 has M core wires 3 and N core wires 6. That is, N / (M + N) shown in Table 1 means the ratio of the core wire 6 to the total number of core wires included in the winding 2.

The evaluation for the peeling of the core wire shown in Table 1 is classified into the following three categories. An evaluation of "○" means that the core wire was not peeled off from the winding 2 before the experiment, and the state before the experiment was maintained even after the experiment. Before the experiment, a small part of the core wire was peeled off from the winding 2, but no further peeling occurred after the experiment, and the case where the state before the experiment was maintained was also evaluated as "○".

The "Δ" evaluation means that the core wire was peeled to some extent before the experiment, but no further peeling occurred after the experiment, and the state before the experiment was maintained. An "x" rating means that a large number of core wire peelings have already been seen before the experiment. The windings 2 evaluated as "◯" and "Δ" can be used, but the windings 2 evaluated as "x" cannot be used.

The evaluation for disconnection of the winding 2 shown in Table 1 is classified into the following three categories. A "○" rating means that there are no surface cracks or breaks after the experiment. A "Δ" rating means that after the experiment, cracks were found on the surface, but no breaks were found. An "x" rating means that the wire was broken after the experiment. The windings 2 evaluated as "◯" and "Δ" can be used, but the windings 2 evaluated as "x" cannot be used.

As a result of the above experiment, as shown in Table 1, in order to improve the strength of the heating coil 1 and prevent the winding 2 from being broken, the ratio of the core wire 6 to the total number of core wires contained in the winding 2 is determined. It is preferably 30% to 50%, more preferably 35% to 45%.

Further, for example, in the core wire 3, the cross-sectional area of the insulating layer 5 is more preferably 20% to 70% of the cross-sectional area of the core wire 3. In the core wire 6, the cross-sectional area of the insulating layer 8 and the fused layer 9 is more preferably 20% to 70% of the cross-sectional area of the core wire 6.

As a result, excessive curing of the winding 2 can be prevented, and disconnection of the winding 2 in the manufacturing process of the heating coil 1 can be further prevented.

[Composition of rice cooker]
Hereinafter, the rice cooker 100 according to the present embodiment will be described with reference to FIG. FIG. 5 is a cross-sectional view of the rice cooker 100.

As shown in FIG. 5, the rice cooker 100 has a main body 10, a lid 11 that covers the upper surface of the main body 10, and a pot 12 that is detachably housed in the main body 10.

The rice cooker 100 has a heating coil 1 configured by using the above-mentioned winding 2 inside the main body 10, and by inducing heating the pot 12 using the heating coil 1, rice and the like in the pot 12 and the like. Cook food.

As shown in FIG. 1, the rice cooker 100 has a heating coil 1 formed in a shape along the bottom surface and the side surface of the pot 12. As a result, the rice cooker 100 can efficiently induce and heat the pot 12.

As described above, according to the present embodiment, it is possible to form the heating coil 1 without disconnection in the manufacturing process. By providing the heating coil 1, it is possible to provide a highly reliable rice cooker 100.

However, the present disclosure is not limited to the above-described embodiment.

The conductors 4 and 7 may be composed of aluminum or an aluminum alloy only. With this configuration, the same effect as the above configuration can be obtained.

The surfaces of the conductor 4 and the conductor 7 may be coated with nickel or tin. With this configuration, it is possible to obtain the same effect as the above-mentioned configuration, and it is possible to improve the workability of the heating coil 1 such as the wettability of solder.

The heating coil according to the present disclosure can be applied not only to an induction heating cooker but also to an induction heating device in general.

1,200 Heating coil 2 Winding 3,6 Core wire 4,7,202 Conductor 4a, 7a, 301 Center conductor 4b, 7b, 303 Coating layer 5,8,203 Insulation layer 9,204 Fusion layer 10 Main body 11 Lid 12 pot 100 rice cooker 302 intermetallic compound layer

Claims (5)

A heating coil with windings
The winding has a first core wire and a second core wire.
The first core wire includes an elongated first conductor and a first insulating layer provided on the surface of the first conductor.
The second core includes a second elongate conductor, a second insulating layer provided on the surface of the second conductor, viewed contains a fusion layer provided on a surface of the second insulating layer, said first A heating coil in which the number of core wires is 30% to 50% of the total number of the first core wires and the number of the second core wires. The first conductor includes a first center conductor provided at the center of the first conductor and a first coating layer provided on the surface of the first center conductor, and has a diameter of 0.1 to 0.3 mm. Have,
The heating coil according to claim 1, wherein the first coating layer has a volume resistance smaller than that of the first central conductor and has a cross-sectional area of 10 to 20% of the cross-sectional area of the first conductor. The second conductor includes a second center conductor provided at the center of the second conductor and a second coating layer provided on the surface of the second center conductor, and has a diameter of 0.1 to 0.3 mm. Have,
The heating coil according to claim 1, wherein the second coating layer has a volume resistance smaller than that of the second central conductor and has a cross-sectional area of 10 to 20% of the cross-sectional area of the second conductor. The heating coil according to claim 1, wherein the fused layer has a melting point lower than that of the first insulating layer and the second insulating layer. A rice cooker provided with the heating coil according to claim 1.

Images