CN212996072U - Cooking device - Google Patents

Abstract

The utility model provides a cooking device, it improves the heating nature of pot. A cooking device (rice cooker (10)) is provided with a storage part (22) for storing a pot (15) and a plurality of coils (25A, 25B). The coils (25A, 25B) are annular, and each have: a first portion (26) that is curved with a first radius of curvature (r1) so as to project toward the axis (A) of the housing (22) and extends along the bottom wall (24a) so as to cross the bottom wall (24 a); a second portion (27) curved at a second radius of curvature (r2) smaller than the first radius of curvature (r1) and extending along the outer peripheral wall (24 b); a third portion (28) of circular arc shape connected to the first end (26a) of the first portion (26) and the first end (27a) of the second portion (27); and a fourth portion (29) of circular arc shape connected to the second end (26b) of the first portion (26) and the second end (27b) of the second portion (27).

Description

Cooking device

Technical Field

The utility model relates to a cooking device.

Background

Patent document 1 discloses an electric rice cooker in which three coils are arranged at intervals in a circumferential direction on a bottom portion of a bottomed cylindrical rice cooker. In this rice cooker, the energization state is switched in a predetermined order so that one of the three coils is energized and the remaining coils are de-energized, and the rice cooker is inductively heated by the coils.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-61573

SUMMERY OF THE UTILITY MODEL

Problem to be solved by the utility model

In the heating device of patent document 1, it is described that a part of the rice cooker is heated intensively by switching the energization state to the coil, but there is room for improvement in the heating performance of the rice cooker by the coil.

The utility model discloses a topic lies in, improves the heating nature of the pot in the cooking ware that possesses a plurality of coils.

Means for solving the problems

One mode of the utility model provides a cooking device, possesses: a housing part having a bottom wall and a cylindrical outer peripheral wall rising from the outer periphery of the bottom wall, and housing a bottomed cylindrical pot; and a plurality of coils arranged in a circumferential direction around an axis of the housing portion on an outer surface side of the housing portion, each of the plurality of coils having an annular shape and including: a first portion that is curved with a first radius of curvature so as to protrude toward an axis of the housing portion when the housing portion is viewed in a direction in which the axis of the housing portion extends, and that extends along the bottom wall so as to cross the bottom wall; a second portion curved at a second radius of curvature smaller than the first radius of curvature and extending along the outer peripheral wall; a third portion having an arc shape, which is connected to a first end of the first portion and a first end of the second portion in one side in a circumferential direction of the receiving portion; and a fourth portion having an arc shape, which is connected to a second end of the other side of the first portion and a second end of the other side of the second portion in the circumferential direction of the receiving portion.

In the cooker, a first section locally heats a bottom surface portion of the pot, a second section locally heats a side surface portion of the pot, and a third section and a fourth section locally heat the bottom surface portion of the pot to the side surface portion. Since the first radius of curvature of the first portion is larger than the second radius of curvature of the second portion, the heating area of the bottom surface portion of the pan can be ensured to be wide. Therefore, the heating performance of the bottom surface side of the pan, which is important in cooking, can be improved.

The first portion to the fourth portion are all arc-shaped, and no straight line portion is provided in the coil. In the case where a linear portion exists in the coil when the coil is manufactured, tension becomes too small at the linear portion, and on the other hand, tension becomes too large at both ends of the linear portion. However, in this method, since there is no straight portion, the single wire or the twisted wire can be wound by applying a predetermined tension to a predetermined portion. This enables the coil to be reliably manufactured in a predetermined shape, and the productivity of the coil to be improved.

The ratio of the first radius of curvature to the second radius of curvature is 100% or more and 160% or less. According to this aspect, the heating region of the first portion with respect to the bottom surface portion of the pan can be effectively ensured.

The thickness of the inner peripheral portion of the third portion is thicker than the thickness of the outer peripheral portion of the third portion, and the thickness of the inner peripheral portion of the fourth portion is thicker than the thickness of the outer peripheral portion of the fourth portion in a direction in which the axis of the housing portion extends. Specifically, the thickness of the third portion and the thickness of the fourth portion are gradually reduced from the inner circumferential portion to the outer circumferential portion. According to this aspect, the number of strands per unit area is greater on the bottom surface side of the pan than on the side surface side, and therefore the amount of heating can be ensured. In addition, on the side surface portion side of the pan, although the number of wires per unit area is reduced, since the range in which the coil can be arranged can be expanded, a heating region can be secured. Further, in the side surface side portion of the pan, the flexibility of the coil is improved by the reduction in the number of strands, so that the adherence to the outer surface shape from the bottom wall to the outer peripheral wall can be improved.

Only two of the coils are provided. The cooker further includes a sensor that penetrates the outer peripheral wall and detects a temperature of the pan, and the two coils are arranged symmetrically with respect to a reference line passing through a center of the bottom wall and the sensor when the receiving portion is viewed in a direction in which an axis of the receiving portion extends. According to this aspect, the bottom surface side of the pan can be heated without being biased by the two coils. In addition, the heating temperature of the pan by the two coils can be detected by one sensor without bias.

A gap between the third portion or the fourth portion closest to the sensor and the sensor is 20mm or less. As described above, by making the thickness of the outer peripheral portion of the third portion and the fourth portion smaller than the thickness of the inner peripheral portion, the heating region of the side surface portion can be enlarged and brought close to the sensor. Further, if the third portion or the fourth portion and the sensor are arranged as in this embodiment, the responsiveness when the temperature of the pot heated by the coil is detected by the sensor can be improved.

The thickness of the first portion and the thickness of the second portion in the direction in which the axis of the housing portion extends are each uniform from the inner peripheral portion to the outer peripheral portion, and the density of the element wires constituting the first portion is higher than the density of the element wires constituting the second portion. According to this aspect, the heating amount per unit area of the bottom surface portion of the pan can be ensured, and the heating region of the side surface portion of the pan can be ensured.

Effect of the utility model

The utility model discloses an among the cooking utensils, because the first radius of curvature of first part is bigger than the second radius of curvature of second part, consequently can improve the heating nature of a plurality of coils to the bottom surface portion side of pot. In addition, since no straight portion is present in the coil, productivity of the coil can be improved.

Drawings

Fig. 1 is a sectional view of a cooking device according to an embodiment of the present invention.

Fig. 2 is an exploded perspective view of the bezel and the coil.

Fig. 3 is a bottom view of the bezel and the coil.

Fig. 4 is a bottom view of a coil.

Fig. 5 is a cross-sectional view taken along line V-V of fig. 4.

Fig. 6 is a sectional view taken along line VI-VI of fig. 4.

Fig. 7 is a partially enlarged view of fig. 5.

Fig. 8 is a partially enlarged view of a portion of fig. 5 different from fig. 7.

Fig. 9 is an enlarged view of fig. 6.

Fig. 10 is a bottom view showing a comparative example in the case of changing the curvature of the first portion of the coil.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 shows an electric rice cooker 10 as an example of a cooking device according to an embodiment of the present invention. The rice cooker 10 includes a rice cooker main body 20 in which a rice cooker (pot) 15 is disposed, and a lid body 35 openably and closably attached to the rice cooker main body 20, and is of a multi-coil type in which a plurality of (two in the present embodiment) coils 25A and 25B are disposed in the rice cooker main body 20. In the present embodiment, the heating performance of the rice cooker 15 is improved by optimizing the shapes of the coils 25A, 25B.

(general electric cooker)

As shown in fig. 1, the rice cooker 15 is made of a magnetic material and has an integral structure formed by press working or casting. The rice cooker 15 has a bottomed cylindrical shape, and includes a disc-shaped bottom surface portion 16 and a side surface portion 17 rising from the outer periphery of the bottom surface portion 16. The side surface portion 17 has a cylindrical shape having an axis passing through the center of the bottom surface portion 16.

The rice cooker main body 20 includes a bottomed cylindrical housing portion 22, and the housing portion 22 is configured to detachably house the rice cooker 15 in the outer case 21. By housing the rice cooker 15 on the inner surface side of the housing portion 22, the axis a of the protective frame 24 (housing portion 22) coincides with the axis of the rice cooker 15. The housing portion 22 is provided below an opening formed in the upper surface of the exterior body 21. The storage section 22 includes: an inner barrel 23 located at a position spaced apart from the upper portion of the side surface portion 17; and a protective frame 24 located at a position spaced apart from the lower portions of the bottom surface portion 16 and the side surface portion 17. The inner barrel 23 is made of metal and has a cylindrical shape with a uniform diameter. The protective frame 24 is made of resin (non-conductive material), and is in the form of a tray disposed at the lower end of the inner body 23.

Referring to fig. 2 and 3, in the protective frame 24, two coils 25A, 25B are arranged in a circumferential direction around the axis a of the protective frame 24 on the outer surface side opposite to the inner surface side in which the rice cooker 15 is housed. Referring to fig. 1, holders 31 for holding ferrite cores 30 are disposed outside the coils 25A and 25B, respectively, and the coils 25A and 25B are held (fixed) between the holders 31 and the protective frame 24. The coils 25A and 25B generate eddy currents by supplying high-frequency current, and inductively heat the rice cooker 15.

As shown in fig. 1, the lid body 35 is rotatably attached to a hinge connection portion 36 located on the back of the rice cooker main body 20 on the right side in fig. 1. The lid body 35 is provided with a heat radiating plate 37 on the inner surface side (lower side in fig. 1) facing the rice cooker 15. An inner lid 38 for closing the upper end opening of the rice cooker 15 is provided below the heat radiating plate 37. The inner lid 38 may be detachable or not detachable from the lid body 35. A cover heater 39 is disposed on the upper surface of the heat radiation plate 37, and the cover heater 39 heats the inner cover 38 through the heat radiation plate 37 to evaporate dew attached to the inner cover 38.

Referring next to fig. 1, in the rice cooker 10, two sensors 41 and 42 are disposed as a detection unit for detecting the temperature inside the rice cooker 15. The first sensor 41 is disposed in the rice cooker main body 20, and the second sensor 42 is disposed in the lid 35. The sensor (side sensor) 41 is disposed so as to penetrate the protective frame 24 and contact the outer surface of the rice cooker 15, and detects the temperature of the water-containing rice or the temperature of the cooked rice inside through the rice cooker 15. The sensor 42 is disposed in contact with the heat releasing plate 37 and detects the temperature inside the rice cooker 15 (the space between the heat releasing plate 37 and the inner lid 38) through the heat releasing plate 37.

The rice cooker 10 is provided with a control board 44 having a control unit (not shown). The control board 44 of the present embodiment is disposed on the front side of the rice cooker main body 20 via the holder 45, but may be disposed on the back side of the rice cooker main body 20 or may be disposed in the lid body 35. The control section is constituted by a single or a plurality of microcomputers and other electronic devices. The control unit controls the coils 25A and 25B and the lid heater 39 based on the temperatures detected by the sensors 41 and 42 to execute a rice cooking process including a preheating step, a strong fire heating (warming-up) step, a boiling maintaining step, and a braising step.

When the rice cooking process is performed, the control unit alternately switches the energization state so that one of the two coils 25A, 25B is energized and the other is de-energized. That is, the first energization state in which the coil 25A is electrically connected to disconnect the coil 25B and the second energization state in which the coil 25B is electrically connected to disconnect the coil 25A are alternately repeated. The switching cycle may be different for each process or may be the same for all processes. However, it is preferable that the switching cycle be longer in the strong fire heating step of rapidly raising the temperature in the rice cooker 15 than in the step other than the strong fire heating step of maintaining (adjusting) the temperature in the rice cooker 15 at a predetermined temperature.

In general, a distribution board provided in a japanese household is 20 amperes at most, and a socket is 15 amperes at most, so that a rated power which can be input per unit time in an electric appliance including such an electric rice cooker 10 is 1500W at most. In the case of an electric rice cooker using one coil covering the entire bottom surface portion 16, the entire rice cooker 15 is induction-heated by a heating amount corresponding to a rated power. In contrast, in the rice cooker 10 of the present embodiment, since the rated power is input to one of the two coils 25A and 25B at the maximum, the corresponding heating region of 1/2 of the rice cooker 15 is induction-heated at the maximum and intensively by the heating amount corresponding to the rated power. Therefore, in the rice cooker 10 of the present embodiment, the maximum heating amount per unit area of the rice cooker 15 can be increased as compared with a rice cooker using one coil. As a result, in the present embodiment, a part of the rice cooker 15 can be heated intensively with a large amount of heat.

The heating region of the rice cooker 15 is a portion located in the magnetic field generated by the energization of the coils 25A, 25B, and its shape corresponds to the shape of the coils 25A, 25B. The amount of heat of the rice cooker 15 corresponds to the magnetic flux of the coils 25A, 25B, which corresponds to the number of the wires 25A (see FIGS. 7 to 9) constituting the coils 25A, 25B. Non-heated areas other than the heated areas in the rice cooker 15 are heated due to heat transfer of the heated areas. As the non-heated area increases, the efficiency of heating the rice cooker 15 by the coils 25A, 25B decreases. That is, in order to improve the heating efficiency of the rice cooker 15, it is important to improve the heating performance of the bottom surface portion 16 side of the rice cooker 15 in addition to the input of electric power. Therefore, in the present embodiment, the coils 25A and 25B disposed on the protective frame 24 are configured as follows.

(outline of bezel and coil)

As shown in fig. 2 and 3, the plurality of coils 25A and 25B have the same configuration and are disposed at predetermined positions on the protective frame 24. Since the number of the coils 25A and 25B is two in the present embodiment, they are arranged symmetrically with respect to the reference line L extending in the radial direction of the protection frame 24. The protective frame 24 has a shape corresponding to the outer surface shape of the lower portion of the rice cooker 15.

Specifically, as shown in fig. 1, the rice cooker 15 includes the bottom surface portion 16 and the side surface portions 17 as described above. The side surface portion 17 is substantially provided with a first portion 17a, a second portion 17b, and a third portion 17 c. The first portion 17a is a curved surface shape having a diameter gradually increasing from the lower side toward the upper side, continuing to the outer periphery of the bottom surface portion 16. The second portion 17b is connected to the upper end of the first portion 17a, and has a conical tube shape with a diameter gradually increasing from the lower side toward the upper side. The third portion 17c is connected to the upper end of the second portion 17b, and has a cylindrical shape with a uniform diameter from the lower side toward the upper side.

Referring to fig. 1 to 3, the protection frame 24 includes: a circular bottom wall 24a located at a position spaced apart from the bottom surface portion 16; and an outer peripheral wall 24b located at a position spaced apart from the side surface portion 17. The outer peripheral wall 24b is a cylindrical wall rising from the outer periphery of the bottom wall 24a, and includes a first portion 24c corresponding to the first portion 17a and a second portion 24d corresponding to the second portion 17 b. The first portion 24c is a curved surface shape having a diameter gradually increasing from the lower side toward the upper side, and is continuous with the outer periphery of the bottom wall 24 a. The second portion 24d is connected to the upper end of the first portion 24c, and has a conical tube shape with a diameter gradually increasing from the lower side toward the upper side.

The protection frame 24 includes an attachment portion 24e to which the sensor 41 is attached. The mounting portion 24e is provided in a second portion 24d of the outer peripheral wall 24b, and includes a circular through hole 24f and a cylindrical protruding portion 24g protruding outward from the periphery of the through hole 24 f. As best shown in fig. 3, the attachment portion 24e protrudes toward one of the 4 corners of the exterior body 21 formed in a substantially rectangular shape in plan view when viewed from the direction extending from the axis a of the protective frame 24. By attaching the sensor 41 to the attachment portion 24e, as shown in fig. 1, the detection portion penetrating the protective frame 24 comes into contact with the second portion 17b of the side surface portion 17. In the present embodiment, the sensor 41 is disposed on the rear side of the package 21, but may be disposed on the front side of the package 21.

As best shown in fig. 2, the protective frame 24 is provided with ribs 24h for positioning the coils 25A, 25B, respectively, and bosses 24i for fixing the holder 31. Referring to fig. 3, the rib 24h and boss 24i for the coil 25A and the rib 24h and boss 24i for the coil 25B are provided symmetrically with respect to a reference line L passing through the center of the bottom wall 24a (the axis a of the protective frame 24) and the mounting portion 24e (the sensor 41). The rib 24h is provided at one (inner) end of the inner circumferential portion 25B of the substantially elliptical coils 25A and 25B in the short axis direction, at the other (outer) end, and at each of the two ends in the long axis direction. Two ribs 24h are also provided between the pair of coils 25A and 25B. The bosses 24i are provided two on the outer side in the short axis direction of the inner peripheral portion 25B of the coils 25A, 25B, and one at each of both ends in the long axis direction.

As shown in fig. 2 to 4, each of the coils 25A and 25B is formed by winding a plurality of element wires 25A (see fig. 7 to 9) in an asymmetric elliptical ring shape. The coils 25A, 25B have a substantially elliptical inner peripheral portion 25B and a substantially semicircular outer peripheral portion 25 c. A first connection line 25d extends from the inner peripheral portion 25b, and a second connection line 25e extends from the outer peripheral portion 25 c. The connection lines 25d and 25e are covered with insulating tubes, and are electrically connected to the control board 44 through the adjacent coils 25A and 25B.

The coils 25A, 25B are respectively arranged in the region from the bottom wall 24a to the first portion 24c of the outer peripheral wall 24B of the protective frame 24 so as to heat the region from the bottom surface portion 16 to the first portion 17a of the side surface portion 17 of the rice cooker 15. As best shown in fig. 3, when the accommodating portion 22 is viewed in a direction extending from the axis a of the accommodating portion 22, the two coils 25A and 25B are arranged in the circumferential direction around the axis a of the protective frame 24 and are arranged symmetrically with respect to the reference line L.

More specifically, as shown in fig. 3 and 4, each of the coils 25A and 25B includes: a first portion 26 extending along the bottom wall 24 a; a second portion 27 extending along the outer peripheral wall 24 b; and a third portion 28 and a fourth portion 29 connected thereto. In fig. 3 and 4, the boundary portions thereof are shown by a one-dot chain line (imaginary line). Each of them is formed in an arc shape having a predetermined curvature, but is not limited to a strict arc shape as long as it is substantially arc-shaped from one end to the other end.

When the receiving portion 22 is viewed in a direction extending from the axis a of the receiving portion 22, the first portion 26 protrudes inward toward the axis a of the receiving portion 22 and is curved with a predetermined radius of curvature (first radius of curvature) r 1. The first portion 26 extends along the reference line L in such a manner as to cross the bottom wall 24 a. The outer peripheral portion 25c of the first portion 26 in the coil 25A and the outer peripheral portion 25c of the first portion 26 in the coil 25B are located at positions separated by a predetermined interval (for example, 10 mm).

The second portion 27 is located on the opposite side of the first portion 26 in the minor axis direction of the inner peripheral portion 25b, and is curved with a curvature radius (second curvature radius) r2 smaller than the curvature radius r1 so as to project in the opposite direction (outward) to the first portion 26. The second portion 27 extends along the first portion 24c of the outer peripheral wall 24b, centered on the axis a of the bezel 24.

The third portion 28 is connected to the first end 26a on the first side of the first portion 26 and the first end 27a on the second portion 27 in the circumferential direction of the receiving portion 22, and is curved with a radius of curvature (third radius of curvature) r3 smaller than the radius of curvature r2 so as to protrude outward in the radial direction of the bezel 24. First end 26a of first portion 26 and first end 27a of second portion 27 are portions located on the same side (one side) in the front-rear direction of package 21.

The fourth portion 29 is connected to the second end 26b on the other side of the first portion 26 and the second end 27b on the other side of the second portion 27 in the circumferential direction of the receiving portion 22, and is curved with a radius of curvature (fourth radius of curvature) r4 smaller than the radius of curvature r2 so as to protrude outward in the radial direction of the protection frame 24. The second end 26b of the first portion 26 and the second end 27b of the second portion 27 are portions located on the opposite side (the other side) from the first ends 26a, 27a in the front-rear direction of the exterior body 21.

The ratio of the curvature radius r1 of the first portion 26 to the curvature radius r2 of the second portion 27 is set to 100% or more and 160% or less, and more preferably 140% or more and 150% or less. As shown by the broken line in fig. 10, if the ratio of the curvature radius is too small, the third portion 28 and the fourth portion 29 are far from the reference line L, and therefore the heating regions of the coils 25A and 25B cannot be secured, and the non-heating region between the adjacent coils 25A and 25B becomes too wide. As shown by the one-dot chain line in fig. 10, if the ratio of the curvature radius is set to be excessively large, the first portion 26 approaches a straight line, and therefore, as described later, the single wire 25A cannot be wound at a predetermined tension when the coils 25A, 25B are manufactured. Therefore, in order to secure the heating region of the first section 26 to the rice cooker 15 and to improve the productivity of the coils 25A, 25B, the ratio of the curvature radius r1 to the curvature radius r2 is preferably set within the above range.

The radius of curvature r3 of the third portion 28 and the radius of curvature r4 of the fourth portion 29 are set to be the same. Thus, as shown in fig. 4, the coils 25A and 25B each have a line-symmetric shape with respect to a center line C extending in the minor axis direction of the inner peripheral portion 25B. Therefore, the one end side and the other end side of the heating region in the direction along the reference line L can be prevented from being different, and therefore the rice cooker 15 can be uniformly heated.

Referring to fig. 3 and 5, the first portion 26 extends along the bottom wall 24a and is formed to be substantially planar with a thickness. The second portion 27 extends in the circumferential direction of the protective frame 24 along the first portion 24c of the outer circumferential wall 24b, and is formed in a curved surface shape having a thickness. The thickness Ta of the first portion 26 in the direction in which the axis a of the bezel 24 extends is uniform from the inner peripheral portion 25b to the outer peripheral portion 25 c. The thickness Tb of the second portion 27 in the direction in which the axis a of the bezel 24 extends is also uniform from the inner peripheral portion 25b to the outer peripheral portion 25 c. The thickness Ta of the first portion 26 of the present embodiment is the same as the thickness Tb of the second portion 27.

A width W1 of the first portion 26 from the inner peripheral portion 25b to the outer peripheral portion 25c is smaller than a width (creeping distance) W2 of the second portion 27 from the inner peripheral portion 25b to the outer peripheral portion 25 c. Referring to fig. 7, a large number of the element wires 25a constituting the first portion 26 are densely wound by applying tension. Referring to fig. 8, the plurality of element wires 25a constituting the second portion 27 are wound to have a gap more than the first portion 26 by applying a weaker tension than the element wires 25a of the first portion 26. That is, the density of the element wires 25a constituting the first portion 26 is higher than the density of the element wires 25a constituting the second portion 27. Thus, even if the thicknesses Ta, Tb are the same and the number of the element wires 25a is the same, the width W1 of the first portion 26 is different from the width W2 of the second portion 27. Further, due to the difference in the widths W1, W2, the amount of heating per unit area of the first portion 26 is larger than the amount of heating per unit area of the second portion 27.

Referring to fig. 4, the third portion 28 and the fourth portion 29 are formed in a line-symmetrical top view shape. Referring to fig. 6, they extend in the radial direction of the protective frame 24 along the first portion 24c of the outer peripheral wall 24b, and are formed in a curved shape having a thickness. The thickness Tc1 of the inner peripheral portion 25b of the third portion 28 is thicker than the thickness Tc2 of the outer peripheral portion 25c of the third portion 28 in the direction in which the axis a of the protective frame 24 extends. Like the third portion 28, the thickness Tc1 of the inner peripheral portion 25b of the fourth portion 29 is thicker than the thickness Tc2 of the outer peripheral portion 25c of the fourth portion 29. The thicknesses Tc1 and Tc2 become thinner from the inner peripheral portion 25b to the outer peripheral portion 25c, respectively.

The thickness Tc1 of the inner peripheral portion 25b of each of the third and fourth portions 28, 29 is thinnest at the central portion 28a, 29a between the first end 26a of the first portion 26 and the first end 27a of the second portion 27. That is, the thickness Tc1 of the inner peripheral portion 25b of the third and fourth portions 28, 29 becomes gradually thinner as it goes away from the first and second portions 26, 27. Similarly, the thickness Tc2 of the outer peripheral portion 25c of each of the third portion 28 and the fourth portion 29 becomes thinner as it goes away from the first portion 26 and the second portion 27, and becomes thinnest at the central portions 28a and 29 a. Referring to fig. 9, the density of the plurality of element wires 25a constituting the third portion 28 and the fourth portion 29, respectively, is higher than the density of the element wires 25a constituting the second portion 27.

In this way, the thickness of the third portion 28 and the thickness of the fourth portion 29 gradually decrease from the inner side in the circumferential direction and the radial direction of the coils 25A and 25B toward the outer side. Therefore, even if the number of the element wires 25a is the same, the surface area of the third portion 28 and the surface area of the fourth portion 29 can be expanded to be larger than the surface area of the first portion 26 and the surface area of the second portion 27. As a result, the outer peripheral portion 25c of the third portion 28 and the outer peripheral portion 25c of the fourth portion 29 can be brought close to the sensor 41. In other words, as shown in fig. 3, the gap S between the mounting portion 24e (sensor 41) and the outer peripheral portions 25c and 25c of the third and fourth portions 28 and 29 can be set within a range in which the detection responsiveness of the sensor 41 is good.

Specifically, the gaps S between the third and fourth portions 28 and 29 and the sensor 41 are 20mm or less, and preferably set to as short a distance as possible. However, in consideration of the ease of assembling the coils 25A and 25B to the protective frame 24, the range of 8mm to 17mm is preferably set. If the gap S is set too small, the assembling property of the coils 25A and 25B to the protective frame 24 may be deteriorated by a manufacturing error of the coils 25A and 25B. If the gap S is set too large, the detection responsiveness of the sensor 41 may be deteriorated. In order to prevent these disadvantages, the gap S is preferably set within the above range.

Next, an example of a method for manufacturing the coils 25A and 25B will be described. However, the method of manufacturing the coils 25A and 25B is not limited to this.

The coils 25A and 25B are manufactured by a coil manufacturing machine provided with a bobbin and a feeder. The bobbin is provided with: a first mold having a first surface having a shape corresponding to the shape of the inner surface of the coils 25A, 25B; and a second mold having a second surface having a shape corresponding to the outer surface shape of the coils 25A, 25B. The feeder feeds a twisted wire obtained by twisting a plurality of (for example, 32) single wires 25a (see fig. 7 to 9).

The spool is rotated about a rotation shaft extending in the vertical direction, and the stranded wire is wound around the spool while a predetermined tension is applied by the feeder. Thus, coils 25A and 25B having a thickness and a shape corresponding to the space between the first mold and the second mold are wound. The portion protruding from the bobbin at which winding starts constitutes a connection line 25d, and the portion protruding from the bobbin at which winding ends constitutes a connection line 25 e. When the winding of the litz wire is completed, the temperature of the element wire 25a is raised by energization. Thereby, the fusion-bonded layer at the outer peripheral portion of the element wire 25a is melted, and the adjacent element wires 25a are fused to each other. As a result, the coils 25A and 25B having a predetermined shape corresponding to the space of the bobbin are formed.

Here, when the coil is D-shaped when viewed in the direction in which the axis a of the protective frame 24 extends, that is, when the first portion 26 is linear, tension cannot be applied to the litz wire toward the second portion 27 when the litz wire is wound around the first portion 26. Further, upon winding of the strands of the first portion 26, a tension of a plurality of degrees is applied to the previously wound third portion 28 or fourth portion 29. That is, since a predetermined tension cannot be applied to a predetermined portion, productivity of the coil is deteriorated.

In the present embodiment, the first portion 26 to the fourth portion 29 are all arc-shaped, and there is no straight portion in the coils 25A, 25B. Therefore, there is no case where the tension becomes too small at the straight portion (the first portion 26) or the tension becomes too large at both ends of the straight portion (the third portion 28 or the fourth portion 29). Therefore, the stranded wire (the element wire 25a) can be wound by applying a predetermined tension to a predetermined portion. This enables the coils 25A and 25B to be reliably manufactured in a predetermined shape, and the productivity of the coils 25A and 25B to be improved.

The electric rice cooker 10 of the present invention configured as described above has the following features.

The first section 26 locally heats the bottom surface part 16 of the rice cooker 15, the second section 27 locally heats the side surface parts 17 of the rice cooker 15, and the third section 28 and the fourth section 29 locally heat the bottom surface part 16 of the rice cooker 15 to the side surface parts 17. Since the first radius of curvature r1 of the first section 26 is larger than the second radius of curvature r2 of the second section 27, the heating area of the bottom surface part 16 of the rice cooker 15 can be ensured to be wide. Therefore, the heating performance of the bottom 16 of the rice cooker 15, which is important in cooking, can be improved. Further, since there is no straight portion in the coils 25A, 25B, productivity can be improved.

The thickness Tc1 of the inner peripheral portion 25b of each of the third and fourth portions 28, 29 is thicker than the thickness Tc2 of the outer peripheral portion 25c of each of the third and fourth portions 28, 29. In addition, the thickness of each of the third portion 28 and the fourth portion 29 becomes gradually thinner from the inner peripheral portion 25b to the outer peripheral portion 25 c. Therefore, the number of strands 25a per unit area on the bottom surface portion 16 side of the rice cooker 15 is larger than the number of strands 25a per unit area on the side surface portion 17 side, and thus the heating amount can be secured. Further, on the side surface part 17 side of the rice cooker 15, although the number of the wires 25A per unit area is reduced, the range in which the coils 25A and 25B can be arranged can be expanded, and thus a heating region can be secured. In addition, the flexibility of the coils 25A, 25B is improved on the side surface portion 17 side of the rice cooker 15 by the reduction in the number of the wires 25A, so that the adhesiveness to the outer surface shape from the bottom wall 24a to the outer peripheral wall 24B can be improved.

Two coils 25A and 25B are provided, and are arranged symmetrically with respect to a reference line L passing through the center of the bottom wall 24a and the sensor 41. Therefore, the bottom surface portion 16 side of the rice cooker 15 can be heated without being biased by the two coils 25A, 25B. The heating temperature of the rice cooker 15 by the two coils 25A and 25B can be detected by the single sensor 41 without being biased.

The gap S between the third portion 28 or the fourth portion 29 closest to the sensor 41 and the sensor 41 is 20mm or less. Therefore, the responsiveness when the temperature of the rice cooker 15 heated by the coils 25A, 25B is detected by the sensor 41 can be improved.

The thicknesses Ta, Tb of the first portion 26 and the second portion 27 are each uniform from the inner peripheral portion 25b to the outer peripheral portion 25c, and the density of the element wires 25a constituting the first portion 26 is higher than the density of the element wires 25a constituting the second portion 27. Therefore, the amount of heat per unit area in the bottom surface portion 16 of the rice cooker 15 can be ensured, and the heating area in the side surface portion 17 of the rice cooker 15 can be ensured.

The electric cooker (cooking device) 10 of the present invention is not limited to the configuration of the above embodiment, and various modifications can be made.

For example, the thickness Ta of the first portion 26 and the thickness Tb of the second portion 27 may be different from each other, or may be different between the inner peripheral portion 25b and the outer peripheral portion 25 c. The thickness of the third portion 28 and the thickness of the fourth portion 29 may be different from each other, or may be the same at the inner circumferential portion 25b and the outer circumferential portion 25 c.

The radii of curvature of the first to fourth portions 26 to 29 and the density of the single lines 25a constituting them may be changed as needed. In particular, the radius of curvature of the third portion 28 and the radius of curvature of the fourth portion 29 may also be different.

The number of coils is not limited to two, and three or more coils may be arranged in the circumferential direction around the axis a of the protective frame 24. In this case, the sensor 41 is preferably disposed at the center of the bottom wall 24a of the protective frame 24.

In the above embodiment, the rice cooker 10 has been described as an example, but the present invention is applicable to any cooking device provided with a bottomed cylindrical housing portion and a plurality of coils disposed on the outer surface side of the housing portion, and similar operations and effects can be obtained.

Description of the symbols

10 electric cooker (cooking device)

15 Rice cooker (pot)

16 bottom surface part

17 side surface part

17a first part

17b second part

17c third part

20 electric cooker main body

21 outer package body

22 housing part

23 inner body

24 protective frame

24a bottom wall

24b outer peripheral wall

24c first part

24d second part

24e mounting part

24f through hole

24g projection

24h rib

24i boss

25 coil

25a single line

25b inner peripheral portion

25c outer peripheral portion

25d connecting line

25e connecting wire

26 first part

26a first end

26b second end

27 second part

27a first end

27b second end

28 third part

28a central portion

29 fourth section

29a central portion

30 ferrite core

31 holder

35 cover body

36 hinge connection

37 heat sink

38 inner cover

39 lid heater

41 sensor

42 sensor

44 control substrate

45 holder

Axis of A protective frame (containing part)

L datum line

S gap

radius of curvature of first portion of r1

radius of curvature of the second portion of r2

r3 radius of curvature of third portion

r4 radius of curvature of fourth section

Thickness of the first part of Ta

Thickness of Tb second portion

Thickness of inner peripheral portions of the third and fourth portions of Tc1

Tc2 thickness of the outer peripheral portions of the third and fourth portions.

Claims (13)

1. A cooker, characterized by having:

a housing part having a bottom wall and a cylindrical outer peripheral wall rising from the outer periphery of the bottom wall, and housing a bottomed cylindrical pot; and

a plurality of coils arranged in a circumferential direction around an axis of the housing portion on an outer surface side of the housing portion,

the plurality of coils are respectively annular and respectively provided with:

a first portion that is curved with a first radius of curvature so as to protrude toward an axis of the housing portion when the housing portion is viewed in a direction in which the axis of the housing portion extends, and that extends along the bottom wall so as to cross the bottom wall;

a second portion curved at a second radius of curvature smaller than the first radius of curvature and extending along the outer peripheral wall;

a third portion having an arc shape, which is connected to a first end of the first portion and a first end of the second portion in one side in a circumferential direction of the receiving portion; and

and the arc-shaped fourth part is connected with the second end of the other side of the first part and the second end of the other side of the second part in the circumferential direction of the accommodating part.

2. The cooker of claim 1,

the ratio of the first radius of curvature to the second radius of curvature is 100% or more and 160% or less.

3. The cooker according to claim 1 or 2,

the thickness of the inner peripheral portion of the third portion is thicker than the thickness of the outer peripheral portion of the third portion, and the thickness of the inner peripheral portion of the fourth portion is thicker than the thickness of the outer peripheral portion of the fourth portion in a direction in which the axis of the housing portion extends.

4. The cooker of claim 3,

the thickness of the third portion and the thickness of the fourth portion are gradually thinner from the inner circumferential portion toward the outer circumferential portion, respectively.

5. The cooker according to any one of claims 1, 2 and 4,

the cooking appliance is provided with only two of the coils.

6. The cooker of claim 3,

the cooking appliance is provided with only two of the coils.

7. The cooker of claim 5,

the cooking utensil is provided with a sensor which penetrates through the peripheral wall and detects the temperature of the pot,

the two coils are arranged symmetrically with respect to a reference line passing through the center of the bottom wall and the sensor when the housing portion is viewed in a direction in which an axis of the housing portion extends.

8. The cooker of claim 6,

the cooking utensil is provided with a sensor which penetrates through the peripheral wall and detects the temperature of the pot,

the two coils are arranged symmetrically with respect to a reference line passing through the center of the bottom wall and the sensor when the housing portion is viewed in a direction in which an axis of the housing portion extends.

9. The cooker according to claim 7 or 8,

a gap between the third portion or the fourth portion closest to the sensor and the sensor is 20mm or less.

10. The cooking appliance according to any one of claims 1, 2, 4, 6 to 8,

the thickness of the first portion and the thickness of the second portion in the direction in which the axis of the housing portion extends are each uniform from the inner peripheral portion to the outer peripheral portion,

the density of the element wires constituting the first portion is higher than the density of the element wires constituting the second portion.

11. The cooker of claim 3,

the thickness of the first portion and the thickness of the second portion in the direction in which the axis of the housing portion extends are each uniform from the inner peripheral portion to the outer peripheral portion,

the density of the element wires constituting the first portion is higher than the density of the element wires constituting the second portion.

12. The cooker of claim 5,

the thickness of the first portion and the thickness of the second portion in the direction in which the axis of the housing portion extends are each uniform from the inner peripheral portion to the outer peripheral portion,

the density of the element wires constituting the first portion is higher than the density of the element wires constituting the second portion.

13. The cooker of claim 9,

the thickness of the first portion and the thickness of the second portion in the direction in which the axis of the housing portion extends are each uniform from the inner peripheral portion to the outer peripheral portion,

the density of the element wires constituting the first portion is higher than the density of the element wires constituting the second portion.

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