CN107535022B

CN107535022B - Heating coil and rice cooker provided with same

Info

Publication number: CN107535022B
Application number: CN201680024450.1A
Authority: CN
Inventors: 大矢弘; 中西清芽; 椿惠; 岩井仁志
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2015-09-02
Filing date: 2016-08-29
Publication date: 2020-10-27
Anticipated expiration: 2036-08-29
Also published as: JPWO2017038074A1; JP6832488B2; CN107535022A; WO2017038074A1

Abstract

The heating coil is provided with a winding (2). The winding (2) has a first core (3) and a second core (6). The first core (3) comprises an elongated first conductor and a first insulating layer arranged on a surface of the first conductor. The second core wire (6) comprises: an elongated second conductor; a second insulating layer disposed on a surface of the second conductor; and a fusion layer disposed on a surface of the second insulating layer. According to the present embodiment, the coil (2) can be prevented from being broken in the heating coil manufacturing process. According to the heating coil of the present embodiment, a highly reliable rice cooker can be provided.

Description

Heating coil and rice cooker provided with same

Technical Field

The present disclosure relates to a heating coil used for an induction heating cooker and a cooker provided with the heating coil.

Background

Conventionally, in the field of induction heating cookers, in order to reduce the weight of a heating coil and the loss of the heating coil, there has been proposed a heating coil using a wire rod having a fusion layer on an insulating layer provided on the surface of a conductor such as a copper wire (for example, see patent document 1).

Fig. 6A is a cross-sectional view of a wire rod of the conventional heating coil 200 described in patent document 1. Fig. 6B is a sectional view of the heating coil 200.

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

As shown in fig. 6B, a plurality of wires 201 are twisted to form an integrated wire 205. After the collective wire 205 is wound into a spiral shape, the collective wire 205 is fused by the fusion layer 204, and then the disc-shaped heating coil 200 is formed.

In the field of high-frequency electric wires, electric wires for suppressing ac resistance, heat generation, and power consumption have been proposed. The electric wire has: an elongated center conductor; a cladding layer disposed on a surface of the center conductor; and an insulating layer disposed on a surface of the clad layer. The clad 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 a conventional high-frequency electric wire 300 described in patent document 2. As shown in fig. 7, the high-frequency electric wire 300 includes a center conductor 301, a clad layer 303, and an intermetallic compound layer 302.

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

The present inventors have studied to suppress heat generation and power consumption of the heating coil by using the conventional high-frequency wire as a conductor of the wire material constituting the conventional heating coil.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 59-086188

Patent document 2: japanese patent No. 5266340

Disclosure of Invention

Problems to be solved by the invention

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

For example, when the conventional high-frequency electric wire described in patent document 2 is combined with the conventional heating coil described in patent document 1, the wire material constituting the collective line of the heating coil includes a center conductor, a covering layer, an insulating layer, and a fusion layer. The center conductor is composed of aluminum or an aluminum alloy. The cladding layer is made of copper and is disposed on the surface of the center conductor. The insulating layer is disposed on a surface of the clad layer. The fusion layer is disposed on a surface of the insulating layer.

The heating coil is formed by twisting a plurality of the wire rods and fusing the collected wires wound in a spiral shape. In this configuration, since the coating layer of the wire rod is made of a metal different from the metal constituting the center conductor of the wire rod, the center conductor of the wire rod and the coating layer of the wire rod have different properties such as ductility. Generally, with respect to ductility, the center conductor of the wire is inferior to the film layer of the wire, since aluminum is inferior to copper.

On the other hand, if all the wires constituting the aggregate line have a fused layer, the aggregate line becomes excessively hard. Therefore, according to the collective wire, there is a possibility that the heating coil is broken in the manufacturing process.

The present disclosure solves the above-described conventional problems, and even if a conductor includes a metal having ductility inferior to copper, a heating coil without disconnection is formed in a manufacturing process. The purpose is to provide a highly reliable rice cooker by providing the heating coil.

In order to solve the above problem, 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 includes an elongated first conductor and a first insulating layer disposed on a surface of the first conductor. The second core wire includes: an elongated second conductor; a second insulating layer disposed on a surface of the second conductor; and a fusion layer disposed on a surface of the second insulating layer.

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

According to the heating coil of the above aspect, the coil can be prevented from being broken in the manufacturing process. Since the heating coil is provided, a highly reliable rice cooker can be provided.

Drawings

Fig. 1 is an overall perspective view illustrating an appearance of a heating coil according to an embodiment of the present disclosure.

Fig. 2 is a perspective view of a coil of the heating coil according to the embodiment.

Fig. 3A is a cross-sectional view of a first core wire constituting a winding of the heating coil of the embodiment.

Fig. 3B is a sectional view of a second core wire constituting a winding of the heating coil of the embodiment.

Fig. 4A is a diagram illustrating a state in which the winding of the heating coil of the embodiment is configured only with the second core wire and deformed.

Fig. 4B is a diagram illustrating a state in which the winding of the heating coil of the embodiment is configured by the first core wire and the second core wire and deformed.

Fig. 5 is a sectional view of a rice cooker according to an embodiment of the present disclosure.

Fig. 6A is a cross-sectional view of a wire rod of a 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.

Detailed Description

A 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 includes an elongated first conductor and a first insulating layer disposed on a surface of the first conductor. The second core wire includes: an elongated second conductor; a second insulating layer disposed on a surface of the second conductor; and a fusion layer disposed on a surface of the second insulating layer. According to this aspect, the coil can be prevented from being broken in the manufacturing process of the heating coil.

According to a 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, the coil can be prevented from being broken in the manufacturing process of the heating coil.

According to a third aspect of the present disclosure, in the first or second aspect, the first conductor includes: a first central conductor disposed at a center of the first conductor; and a first cladding layer disposed on a surface of the first center conductor, the first conductor having a diameter of 0.1-0.3 mm. The first cladding layer has a volume resistance smaller than that of the first central conductor and has a cross-sectional area 10-20% of a 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 at the heating coil can be reduced.

According to a fourth aspect of the present disclosure, in any one of the first to third aspects, the second conductor includes: a second central conductor disposed at a center of the second conductor; and a second cladding layer disposed on a surface of a second center conductor, the second conductor having a diameter of 0.1-0.3 mm. The second cladding layer has a volume resistance smaller than that of the second central conductor and has a cross-sectional area 10-20% of that of the second conductor.

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

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

A sixth aspect of the present disclosure is a rice cooker including the heating coil according to any one of the first to fifth aspects. According to this aspect, since the heating coil which is not disconnected in the manufacturing process is used, a highly reliable rice cooker can be provided.

Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the following description, the same or corresponding portions are denoted by the same reference numerals, and overlapping 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 fig. 1 to 4B. As will be described later, the induction heating cooker of the present embodiment is a rice cooker 100 (see fig. 5).

Fig. 1 is a perspective view showing an appearance of the heating coil 1. Fig. 2 is a perspective view of the coil 2 constituting the heating coil 1. Fig. 3A and 3B are cross-sectional views showing the

core wires

3 and 6 constituting the winding 2, respectively.

As shown in fig. 1, a heating coil 1 is formed by winding a single elongated coil 2 into a spiral shape. As shown in fig. 2, the winding 2 is formed by twisting an integrated 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 center 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 center conductor 7a provided at the center of the conductor 7; and a coating layer 7b provided on the surface of the conductor 7.

An aggregate wire obtained by twisting the

core wires

3 and 6 is wound around a jig, and when a high-frequency current is supplied to the aggregate wire, the aggregate wire generates heat. By this heat generation, the fusion layer 9 of the core wire 6 melts. As a result, the core wire 3 is fused with the core wire 6 to form the winding 2.

In addition, the core 3 corresponds to a first core, and the core 6 corresponds to a second core. The conductor 4 corresponds to a first conductor, and the conductor 7 corresponds to a second conductor. The insulating layer 5 corresponds to a first insulating layer, and the insulating layer 8 corresponds to a second insulating layer. The central conductor 4a corresponds to a first central conductor, and the central conductor 7a corresponds to a second central conductor. The clad layer 4b corresponds to the first clad layer, and the clad layer 7b corresponds to the second clad layer.

In the induction heating cooker, 20 to 100kH_ZWhen the high-frequency current of (2) is supplied to the heating coil, the current is concentrated on the surface of the conductor due to the skin effect. Therefore, in the case where the conductor has a center conductor and a coating layer provided on the surface of the center conductor, it is necessary to reduce the resistance value of the coating layer, which is the surface portion of the conductor, to suppress heat generation and power consumption of the heating coil.

In order to reduce the burden on the user, it is preferable that the portable home electric appliance such as a rice cooker be light in weight. In the present embodiment, the

central conductors

4a and 7a have a small volume resistance and are made of a lightweight material, aluminum, or a metal containing aluminum.

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

clad 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 central conductor 7a to the coating layer 7b, and the like are set according to the application of the heating coil 1.

As mentioned above, the flow rate is 20 to 100kH_ZIn the high-frequency current heating coil 1 of (2), the diameter of the

conductors

4 and 7 is preferably set to 0.1 to 0.3mm, more preferably 0.25 mm.

Preferably, the cross-sectional area of the coating layer 4b is set to 10 to 20% of the cross-sectional area of the conductor 4 having the diameter. More preferably, it is set to 15%. The conductor 7 is also similar to the conductor 4.

According to 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 of the heating coil 1 can be reduced.

Preferably, the insulating

layers

5 and 8 are made of F-type or H-type insulating materials according to the electrical product 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 the insulating

layers

5 and 8 and higher than the temperature of the heating coil 1 during operation, for example, a polyamide resin. According to this structure, the fusion layer 9 melts at a temperature lower than the melting point of the insulating

layers

5, 8.

Therefore, when the core wire 3 and the core wire 6 are fused together to form the winding 2 of the heating coil 1 by bundling the core wire 3 and the core wire 6, the

conductors

4 and 7 can be reliably insulated by the insulating

layers

5 and 8, respectively, without damaging the

insulating layers

5 and 8.

Next, the characteristics of the heating coil 1 of the present embodiment will be explained.

As described above, the plurality of core wires 3 not including the fusion layer 9 and the plurality of core wires 6 including the fusion layer 9 are twisted and fused to form the winding 2 of the heating coil 1.

The former winding 2 is more firmly fixed than the latter winding, comparing the case where the winding 2 is constituted only by the core wire 6 having the fusion layer 9 with the case where the winding 2 is constituted by the core wire 3 not having the fusion layer 9. Therefore, the former is less likely to change the cross-sectional shape of the winding 2 when the winding 2 is bent than the latter. Therefore, the

former core wires

3, 6 located outside the bent winding 2 are extended longer than the latter.

In the present embodiment, the conductor 4 of the core wire 3 includes: a center conductor 4a made of aluminum or an aluminum alloy; and a clad layer 4b made of copper. The conductor 7 of the core wire 6 includes: a center conductor 7a made of aluminum or an aluminum alloy; and a clad layer 7b made of copper. Therefore, if the coil 2 is extended long, the

central conductors

4a and 7a having poor ductility may be broken.

In the present embodiment, in order to prevent the

central conductors

4a, 7a from being disconnected, the winding 2 is configured to include not only the core wire 6 having the fusion layer 9 but also the core wire 3 not having the fusion layer 9. According to the present embodiment, the coupling force between the core wires can be reduced, and the winding 2 can be formed more flexibly. As a result, the winding 2 can be prevented from being broken in the manufacturing process.

The following more specifically describes the present invention. The elongation of the bent winding 2 is determined according to the bending radius and the distance from the neutral plane to the outer periphery of the bent winding 2. The larger the elongation of the winding 2, the longer the winding 2 is extended, and the more easily the wire is broken.

Fig. 4A is a diagram showing a state in which the winding 2 including only the core wire 6 is bent. As shown in fig. 4A, when the diameter of the coil 2 is D0, the bending radius of the coil 2 is R1, the distance from the neutral plane F of the coil 2 to the outer periphery of the coil 2 is L1, and the elongation of the coil 2 is H1, the elongation H1 is expressed by formula (1).

H1＝L1/R1(1)

In the winding 2 having only the core wire 6, since the winding 2 is formed harder, the sectional shape of the winding 2 hardly changes when the winding 2 is bent at the bending radius R1. Therefore, in this case, the distance L1 from the neutral plane F to the outer periphery of the coil 2 is expressed by equation (2).

L1＝D0/2 (2)

Fig. 4B is a diagram showing a state in which the winding 2 including the

core wires

3, 6 is bent. As shown in fig. 4B, when the diameter of the coil 2 is D0, the bending radius of the coil 2 is R1, the distance from the neutral plane F of the coil 2 to the outer periphery of the coil 2 is L2, and the elongation of the coil 2 is H2, the elongation H2 is expressed by formula (3).

H2＝L2/R1 (3)

In the case shown in fig. 4B, the coupling force between the core wires is weaker than that in the case shown in fig. 4A, and the winding 2 is flexible. Therefore, when the winding 2 is bent, the cross-sectional shape of the winding 2 becomes an elliptical shape as shown in fig. 4B. At this time, if the long diameter and the short diameter of the cross-sectional shape of the winding 2 are D1 and D2, respectively, the distance L2 from the vertical plane F to the outer periphery of the winding 2 is half of the short diameter D2.

Since the short diameter D2 is smaller than the diameter D0, the elongation H2 of the winding 2 in the case shown in fig. 4B is smaller than the elongation H1 of the winding 2 in the case shown in fig. 4A.

Therefore, in the case where the heating coil 1 is formed using the coil 2 in the case shown in fig. 4B, the coil 2 does not extend long as compared with the case where the heating coil 1 is formed using the coil 2 in the case shown in fig. 4A. As a result, the winding 2 can be prevented from being broken in the manufacturing process.

[ ratio of core wire 6 in winding 2 ]

Next, the heating coil 1 of the present embodiment will be described in more detail.

If the proportion of the core wire 6 in the winding 2 increases, the amount of the fusion layer 9 contained in the winding 2 increases, and the winding 2 is fixed more firmly. As described above, with the winding 2 being firmly fixed, the possibility of the winding 2 breaking when the heating coil 1 is formed increases.

On the other hand, when the ratio of the core wires 6 in the winding 2 is decreased, the amount of the fusion layer 9 included in the winding 2 is decreased, the bonding force between the core wires is decreased, and the winding 2 becomes flexible. Therefore, the possibility of the coil 2 being broken when the heating coil 1 is formed is reduced. However, if the bonding 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 reduced.

Therefore, in order to increase the strength of the heating coil 1 and prevent the breakage of the winding 2, it is necessary to form the winding 2 with the core wire 3 and the core wire 6 at an appropriate ratio.

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

In the present experiment, a heating coil 1 formed of a winding 2 of

core wires

3, 6 having the following structure was used. The core wire 3 has: a conductor 4 having a diameter of 0.25 mm; and an insulating layer 5 composed of F kinds of insulating materials. The conductor 4 includes: a center conductor 4a made of aluminum or an aluminum alloy; and a clad 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 F kinds of insulating materials; and a fusion layer 9 made of a polyamide resin. The conductor 7 includes: a center conductor 7a made of aluminum or an aluminum alloy; and a clad layer 7b made of copper.

In this experiment, with respect to the winding 2 in which the ratio of the core wire 6 to the total number of the

core wires

3 and 6 was 25% to 55%, the presence or absence of core wire separation in the winding 2 and the presence or absence of wire breakage in the winding 2 were confirmed after the 90-degree bending was performed a predetermined number of times (for example, 2 or 3 times).

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

[ Table 1]

N/(M+N)

25％

30％

35％

40％

45％

50％

55％

Peeling off

×

△

○

Wire break

○

△

×

The evaluations of the peeling of the core wires shown in table 1 are classified into the following three categories. The evaluation "o" means that no peeling of the core wire was observed in the coil 2 before the experiment and the state before the experiment was maintained even after the experiment. Before the experiment, only a part of the core wires were separated from the coil 2, but further separation did not occur after the experiment, and the state before the experiment was maintained.

The evaluation "Δ" means that some peeling of the core wire was observed before the experiment, but no further peeling occurred after the experiment, and the state before the experiment was maintained. The "x" evaluation means that peeling of a plurality of core wires was already visible before the experiment. Windings 2 evaluated by ". smallcircle" and "Δ" can be used, but windings 2 evaluated by "x" cannot be used.

The evaluation of the wire breakage of the winding 2 shown in table 1 is classified into the following three categories. The evaluation of "o" means that neither surface cracking nor line breakage occurred after the test. The evaluation "Δ" means that no line breakage occurred although cracks were visible on the surface after the experiment. The evaluation of "x" means that disconnection occurred after the experiment. Windings 2 evaluated by ". smallcircle" and "Δ" can be used, but windings 2 evaluated by "x" cannot be used.

As a result of the above experiment, as shown in table 1, in order to increase the strength of the heating coil 1 and prevent the disconnection of the winding 2, the ratio of the core wire 6 to the total number of core wires included in the winding 2 is preferably 30% to 50%, and more preferably 35% to 45%.

Further, for example, in the core wire 3, it is more preferable that the sectional area of the insulating layer 5 is 20% to 70% of the sectional area of the core wire 3. In the core wire 6, it is more preferable that the sectional area of the insulating layer 8 and the fusion layer 9 is 20% to 70% of the sectional area of the core wire 6.

This can prevent excessive hardening of the coil 2 and can further prevent the coil 2 from being broken in the manufacturing process of the heating coil 1.

[ Structure of Rice cooker ]

Next, a rice cooking device 100 according to the present embodiment will be described with reference to fig. 5. Fig. 5 is a sectional view of the rice cooker 100.

As shown in fig. 5, the rice cooker 100 includes: a main body 10; a cover 11 covering an upper surface of the main body 10; and a pot 12 detachably accommodated in the main body 10.

The rice cooker 100 includes a heating coil 1 configured by using the coil 2 in the main body 10, and cooks food such as rice in the pan 12 by inductively heating the pan 12 using the heating coil 1.

As shown in fig. 1, the rice cooker 100 has a heating coil 1 formed in a shape along the bottom and side surfaces of a pan 12. Thus, the rice cooker 100 can efficiently perform induction heating of the pot 12.

As described above, according to the present embodiment, the heating coil 1 having no disconnection in the manufacturing process can be formed. Since the heating coil 1 is provided, the rice cooking device 100 with high reliability can be provided.

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

The

conductors

4, 7 may be composed of only aluminum or an aluminum alloy. According to this configuration, the same effects as those of the above configuration can be obtained.

The surfaces of the

conductors

4 and 7 may also be coated with nickel or tin. According to this configuration, the same effects as those of the above configuration can be obtained, and the workability of the heating coil 1 such as the wettability of solder can be improved.

Industrial applicability

The heating coil of the present disclosure is applicable not only to induction heating cookers but also to all induction heating devices.

Description of the reference symbols

1. 200 heating coil

2 winding

3. 6 core wire

4. 7, 202 conductor

4a, 7a, 301 center conductor

4b, 7b, 303 cladding

5. 8, 203 insulating layer

9. 204 fusion layer

10 main body

11 cover body

12 pan

100 cooker

302 intermetallic layer

Claims

1. A heating coil provided with a winding, wherein,

the winding has a first core and a second core,

the first core includes: an elongated first conductor; and a first insulating layer disposed on a surface of the first conductor,

the second core wire includes: an elongated second conductor; a second insulating layer disposed on a surface of the second conductor; and a fusion layer disposed on a surface of the second insulation layer, the second core wire having the fusion layer and the first core wire not having the fusion layer constituting the winding.

2. The heating coil according to claim 1,

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.

3. The heating coil according to claim 1,

the first conductor includes: a first central conductor disposed in the center of the first conductor; and a first cladding layer provided on a surface of the first center conductor, the first conductor having a diameter of 0.1 to 0.3mm,

the first cladding layer has a volume resistance smaller than that of the first central conductor and has a sectional area 10-20% of that of the first conductor.

4. The heating coil according to claim 1,

the second conductor includes: a second center conductor disposed at a center of the second conductor; and a second cladding layer provided on a surface of the second center conductor, the second conductor having a diameter of 0.1 to 0.3mm,

the second cladding layer has a volume resistance smaller than that of the second central conductor and has a sectional area 10-20% of that of the second conductor.

5. The heating coil according to claim 1,

the fusion layer has a melting point lower than the first insulating layer and the second insulating layer.

6. A rice cooker, wherein,

the rice cooking utensil is provided with the heating coil of claim 1.