JP2007080749A - Induction heating cooking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a heating coil for induction heating cooking devices for improving heating efficiency, simplifying the winding process of a heating coil, and securing finished strength. <P>SOLUTION: In the heating coil for induction heating cooking devices in which coil winding is wound around a base surface in a disk shape in a plurality of stages with a winding center axis as a center, the coil winding comprises a first slanting axis, having an angle that exceeds 0 degrees and is less than 90 degrees to the base surface, and a second one symmetrical to the first one to the winding center axis. One side on the first and second slanting axes is made equilateral, and winding is made so that the coil winding is arranged at each apex of a substantially isosceles triangle having one side on a surface in parallel with the winding plane and at each apex of the translated triangle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an induction heating cooker, and more particularly to a heating coil.

  A heating coil used in a conventional induction heating cooker is a twisted litz wire made by twisting a plurality of conductive wires insulated with enamel or the like, and winding this litz wire on substantially the same circumference, Used as a heating coil. In this way, when a high-frequency current is passed through the heating coil, the current density in the cross-sectional area of the conducting wire flows only to the outer periphery of the conducting wire due to the so-called skin effect, and the effective resistance increases. The surface area can be increased and reduced.

  However, when a large number of conductors are used, a phenomenon called a proximity effect appears due to the current of adjacent conductors, and a current density bias occurs as in the skin effect, making it difficult to reduce the effective resistance value.

  When the effective resistance value of the heating coil increases, the heating coil itself generates heat, and measures such as increasing the size of the cooling means for cooling the heating coil and improving heat resistance are required.

  In order to improve these problems, the portion of the coil winding of the heating coil that is wound vertically in n stages and the portion that is wound vertically in the n + 1 stage are alternately stacked, and the same as the conventional induction heating coil. Proposals have been made to increase the output by increasing the number of turns with the outer diameter and to improve the heating efficiency by increasing the ratio of the coil conductor to the space volume of the heating coil (see, for example, Patent Document 1).

JP 2004-171928 A

  However, in the above prior art, although the number of turns of the heating coil is increased and the electromagnetic coupling between the heating coil and the object to be heated is improved to improve the heating efficiency, the heating coil itself is improved. Since the length of the wire becomes long, there is a problem that the increase in the resistance value of the heating coil increases the loss and makes cooling difficult.

  Also, if the increase in the number of turns is reflected in the direction of increasing the number of stacks of the heating coil, the magnetic path length between the heating coil and the load becomes relatively long, so that the electromagnetic coupling is deteriorated and the heating efficiency is deteriorated. There is a problem.

  Moreover, when the number of stacked heating coils increases, it becomes difficult to arrange the coil windings of the heating coils in the thickness direction. Specifically, when winding the coil winding, unless the coil winding tension and the coil winding pulling angle with respect to the winding direction are finely controlled, the coil winding is not wound in alignment, There is a problem that gaps are likely to occur, the shape is not uniform, and the quality is not stable.

  The present invention has been made to solve at least one of the above problems.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In claim 1, induction heating cooking provided with an overheated coil in which a plurality of coil windings are wound in a disk shape around a base surface around a winding central axis. The heating coil includes a first tilt axis having an angle of greater than 0 degrees and less than 90 degrees with respect to the base surface, and a second tilt axis that is symmetrical to the first tilt axis with respect to the winding center axis. Each of the first and second inclined axes is equilateral, and each vertex of a substantially isosceles triangle having one side on a plane parallel to the winding plane, and the parallel movement of the vertices Coil windings are arranged at each vertex of the triangle.

  According to a second aspect of the present invention, the heating coil is coil winding of any one of the (n-1) th and at least n-4th windings in the cross section in the nth winding except before and after the coil winding arrangement moving part. It is intended to touch the line.

  According to a third aspect of the present invention, the coil winding disposed on the bottom surface or the top surface of the heating coil wound in a disk shape is of the same winding plane adjacent to the coil winding except for the front and back of the winding arrangement moving portion. It has a portion in contact with the coil winding.

  According to a fourth aspect of the present invention, the coil winding has a heat-adhesive coating portion by heat.

  According to the first aspect of the heating coil for induction heating cookers of the present invention, according to claim 1, it is not necessary to increase the strength of the winding tension at the time of winding the coil winding more than necessary. It is possible to reduce the coil winding covering and the damage of the wire due to the extension of the coil winding and the contact with the coil winding jig, and the coil winding jig itself can be simplified. This contributes to cost reduction and yield improvement.

  Further, if the angle between the first inclined axis and the base surface is set to 60 degrees, for example, the stacking direction is overlapped in a state shifted by ½ of the diameter of the coil winding. Coil windings are arranged, and the finished height of the heating coil is lower than that of a simple step stack. As a result, the magnetic path length between the heating coil and the load (pan) is shortened. As a result, the magnetic resistance is reduced, the magnetic lines generated from the heating coil efficiently reach the load, and the heating efficiency is increased.

  Moreover, according to Claim 2 and Claim 3, it arrange | positions so that a coil winding may contact, By this contact part, the intensity | strength as a heating coil can be improved and a deformation | transformation and dropout can be prevented. , Leading to improved shape stability.

  In addition, according to claim 4, by using a coating having heat self-bonding property to the coil winding itself, it becomes possible to bond by heat between multi-stage litz wires, using an adhesive or a curing agent. There is no need to maintain the shape of the heating coil, and adhesion to other steps can be ensured even if no adhesive or hardener spreads over the non-exposed part of the intermediate step part, which greatly improves the workability. In addition, the strength of the heating coil can be secured.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the relationship between a heating coil and a load (pan) of an induction heating cooker. In the figure, a pan 10 which is an object to be heated is placed on a top plate 11, a heating coil 1 is provided under the top plate 11, and a high frequency current is passed through the heating coil 1 to inductively heat the pan 10. To do.

  FIG. 2 is a longitudinal sectional view of a heating coil for an induction heating cooker showing an embodiment of the present invention. In the figure, a heating coil 1 is a cross section of a coil winding 2 made of a bundle of litz wires obtained by twisting a plurality of conductive wires insulated with enamel or the like and wound in a disk shape. In addition, the coil winding 2 has a self-bonding coating portion that has heat self-bonding properties, and heat-bonds the coil windings 2 wound in multiple stages to form the shape of the heating coil 1. Hold.

  The coil base 3 is for holding the heating coil 1 and is made of an insulator. The ribs 4 are provided at the central portion and the outermost peripheral portion of the coil base 3 and are for positioning the heating coil 1.

  Further, the heating coil 1 is mounted so as to be fitted inside the ribs 4 at the central portion and the outermost peripheral portion. The magnetic body 5 such as ferrite is disposed below the coil base 3 so that the magnetic flux spreads below the heating coil 1 to prevent erroneous heating of the nearby metal and to prevent noise caused by magnetic lines of force. belongs to.

  FIG. 3 is a detailed vertical cross-sectional view of the winding portion of the heating coil 1 and shows a part of the cross section of the heating coil 1 in which the number of stacking stages of the heating coil 1 is two.

  In the figure, x is the base surface of the base 3 to hold the coil, x1 and x2 are parallel translations of the base surface x, and y is the winding center axis of the coil winding 2.

  a is a first tilt axis with respect to the base surface x, and has an angle of θ1 with respect to the base surface x, that is, an angle of 60 degrees in the embodiment of FIG. Note that the angle θ1 of the first tilt axis a with respect to the base surface x may be an angle greater than 0 degree and less than 90 degrees.

  b is a second tilt axis b symmetrical to the first tilt axis a with respect to the winding center axis y, and in the embodiment of FIG. 3, the angle θ2 with respect to the base surface x is 120 degrees.

  a1, a2,... are obtained by translating the first inclined axis a, and b1, b2,... are obtained by translating the second inclined axis b.

  r represents the radius of the coil winding 2 formed of litz wire, and the cross section of the coil winding 2 is regarded as a circle and represents the distance from the center thereof.

  Then, the coil winding 2 starts to be wound from a distance p from the winding center axis y, and the position of the coil winding 2 is shifted by the radius r of the coil winding 2 in the outer circumferential direction every time one turn is performed, as shown in FIG. Next to the surface is a surface of x2, and the next surface is wound with the surface of x1.

  That is, each vertex on the first and second inclined axes a and b is equilateral, and each vertex of a substantially isosceles triangle having one side on a plane parallel to the winding plane is translated in the outer circumferential direction. The coil winding 2 is wound in a disc shape so that the center of the coil winding 2 is disposed at each vertex of the triangle. By winding in this way, the position of the litz wire itself of the coil winding 2 is sequentially changed, so there is also an effect of reducing the loss due to the proximity effect.

  At this time, the finished height h1 of the heating coil 1 is approximately as follows.

This finished height h1 is h1 <h2 as compared with the finished height h2 of the conventional heating coil in which the coil winding 2 having a radius r shown in FIG. Obviously, the distance between the center of the heating coil 1 in the thickness direction and the load, which is a heated object such as a pan placed on the heating coil 1, or the ferrite 5 provided below the coil base 3. Therefore, the magnetic path length is shortened. As a result, the magnetic resistance is reduced, and the heating efficiency of the load, which is a heated object such as a pan, can be expected.

  FIG. 4 is a detailed longitudinal sectional view of a winding portion of a heating coil having two stacks according to the present invention, and FIG. 5 is a detailed longitudinal sectional view of a winding portion of a heating coil having two conventional stacking steps. . As shown in the figure, the winding jig defines the finished height of the heating coil 1, and the finished height of the heating coil 1 is determined by the upper and lower side walls of a disk-shaped winding jig for winding the coil winding 2. Is specified. The winding jig includes a method in which a gap between the disk-shaped winding jigs is ensured and the number of stacking stages of the heating coils 1 is increased, and a method in which the winding jig is stacked with the coil base 3 as a part of the winding jig.

  Whichever method is used, the coil winding 2 starts to be wound near the center of the winding jig (near the center of the heating coil 1) and wound toward the outer periphery.

  FIG. 4 shows a structure in the middle of winding the heating coil 1 having two winding stages. The n-th winding coil winding 2 is the (n-1) -th winding of the previous coil winding 2. And the coil winding 2 before the second winding is wound while being in contact with the (n-2) th winding. In addition, either the upper side wall or the lower side wall of the winding jig is in contact. And since it will be in the form of winding in the recessed part for the radius r of the coil winding 2 already wound, there is no possibility that the shift | offset | difference of an up-down direction will arise.

  In other words, there is no need to forcibly apply a winding tension in the vertical direction, and it is sufficient to apply the necessary tension only in the tangential direction of the winding direction, so that the vertical tension generating means can be omitted for the winding jig. The device for winding the coil winding 2 can be simplified.

  On the other hand, in the prior art shown in FIG. 5, since the coil windings 2 are arranged in a lattice pattern, the n-th winding coil winding 2 is the (n-1) th winding of the previous coil winding 2. Although it is in contact with two places on the upper or lower side wall of the winding jig, the holding side does not have a holding force on the opposite side of the portion in contact with the upper wall surface or the lower wall surface of the winding jig, and it tends to fall in the direction of arrow A . In order to avoid this, the tension b1 may be applied in the direction of the lower side wall of the winding jig in the direction of arrow B. However, the necessary tension b1 is long because the distance to the winding end surface of the winding jig is long near the beginning of winding. In order to obtain the coil winding force, it must be pulled with a large force. The coil winding 2 is damaged by contact with the edge of the upper or lower side wall of the winding end surface of the winding jig, or the coil is wound with a strong tension b1. There is a risk of elongation of the wire 2.

  FIG. 6 is a detailed longitudinal sectional view of a winding portion of a heating coil having three stacks according to the present invention. The coil winding 2 in the middle of winding is always at least four turns in the cross section in the n-th winding except before and after the arrangement moving portion of the coil winding 2 and the n-1th winding of the coil winding 2 one turn before. The coil winding 2 is wound so as to be in contact with the n-2th, n-3th, or n-4th of the previous coil winding 2. Further, the first and third coil windings 2 in the number of stacked stages are in contact with either the upper side wall or the lower side wall of the winding jig.

  The coil winding 2 wound in the second stage of the stacking stage is not in contact with the upper and lower walls of the winding jig, but is in contact with one point (C) in the winding center direction at an inclination angle θ1 or θ2. Contact the coil winding 2 already wound at point (D). Although there is a possibility of falling into the coil winding 2 portion arranged in the next winding (n + 1), it can be avoided by applying a weak tension b2 in the opposite direction.

  This is because, unlike the conventional case shown in FIG. 5, the contact angle between the coil windings 2 becomes an acute angle, so that the arrangement stability is improved. Further, since the coil winding 2 wound in the second stage is separated from the lower side wall of the winding jig, the end surface of the winding jig and the coil winding are also applied when the tension b2 is applied to the winding start portion. Since the contact of the wire 2 is difficult to occur and the tension b2 in the vertical direction is weak even if it comes into contact, the occurrence of scratches and elongation on the coil winding 2 can be significantly reduced.

  Further, the finished height h3 of the coil in FIG. 6 is expressed by the following equation.

  As shown in FIG. 5, this finished height h3 is obtained by simply adding two stages of the coil winding 2 to the one obtained by simply superimposing two stages of the coil winding 2, and finishing height h4 in the case of the conventional case. Since h4 = 6r, it is clear that h3 <h4, and there is an effect of shortening the magnetic path length as in the case of the two-stage stacking. The improvement of the heating efficiency of the load, which is a heated product, can be expected.

  FIG. 7 is an explanatory diagram for ensuring the strength of a heating coil having two stacks according to the present invention. FIG. 7A shows that the angle of the first inclined axis a with respect to the base surface x is 45 degrees, and the heating coil 1 The number of winding stages is 2. In this way, if the necessary number of turns is ensured by changing the inclination angle with respect to the base surface x or changing the number of stacks of the coil winding 2 depending on the required number of turns of the heating coil 1 with respect to the outer diameter of the heating coil 1. good.

  In the figure, while the coil winding 2 is being wound by the winding jig, the coil winding 2 contacts the coil windings 2 and the upper and lower side walls of the winding jig at points f, h, i, and g. To do. If the coil winding 2 is self-fused by heat in this state, the coil shape is finished while being held, but when the winding jig is removed, the coil windings 2 are fused only at points h and i. Will be. Therefore, there is a weak point that when the force is applied to the heating coil 1, the heating coil 1 is easily deformed. However, when the coil base 3 also serves as a winding jig, the coil base 3 is also held at the point f, so that it is difficult to deform.

  On the other hand, as shown in FIG. 7B, when the angle of the first inclined axis a with respect to the base surface x is 60 degrees and the equilateral triangle is arranged, the coil winding 2 is a point compared to FIG. 7A. Since contact points j and k are added, if the coil winding 2 is self-bonded, the strength against deformation can be increased. This is the same even when the number of winding stages is three.

  FIG. 8 is an explanatory diagram for ensuring the strength of a heating coil having three stacking stages. FIG. 8 (a) shows a conventional arrangement of three and two alternating stacking stages, and FIG. 8 (b) shows a main coil. The angle of the first tilt axis a according to the invention is 60 degrees and the number of stacking stages is three. Comparing FIG. 8 (a) and FIG. 8 (b), the coil winding 2 in the portions s and t in FIG. 8 (a) has only three contact portions with other coil windings 2, and both It concentrates on the half surface side of the coil winding 2, and as a result, it becomes a weak place in strength. However, in the case of FIG. 8B of the present invention, the coil windings arranged on the bottom surface or the top surface are wound on the same winding plane adjacent to the coil windings except for the front and back of the winding moving portion. Is in contact with. That is, the coil windings 2 of the u and v portions arranged on the upper and lower surfaces are all in contact with the other coil windings 2 at four locations, and the two locations are coils of the same winding plane sandwiching the coil winding 2 Since it is in contact with the winding 2, the strength is high.

  FIG. 9 is an explanatory view after a deforming operation of the finished shape in the present invention, and FIG. 9A is a case where the coil winding 2 is wound while applying tension to deform the cross section of the coil winding 2, FIG. 9B shows the case where the coil winding 2 is deformed in section by applying a force to the winding jig after winding.

  In any case, the relationship between the angles θ1 and θ2 formed by the first tilt axis a with respect to the base surface x and the second tilt axis b symmetrical to the first tilt axis a with respect to the winding center axis y is maintained. The positional relationship between the adjacent coil windings is in a position obtained by translating an approximately isosceles triangle, and the above-described effects appear unchanged.

  Therefore, the method according to the present invention is effective even in the case where the space efficiency is increased by increasing the wire filling rate of the cross section by a method such as applying a tension in advance or applying a force to the winding jig later.

  In addition, when the number of stacks of the coil winding 2 is three or more, the coil winding 2 that is hidden inside other than the upper and lower surfaces is present, and therefore the coil winding 2 having a coating portion having self-fusing property due to heat. Must be used.

  In addition, the number of stacks is not limited to three, and the coil winding 2 itself can be thermally bonded between the coil windings 2 of the multi-stack by using a coating having heat self-fusing property. Since it is not necessary to maintain the shape of the heating coil 1 using an agent or a curing agent, and adhesion to other steps can be ensured even if the adhesive or curing agent does not spread over the unexposed portion of the intermediate portion of the stacking, Not only can the workability be greatly improved, but also the strength can be secured.

  Thus, it is not necessary to increase the strength of the winding tension at the time of winding the coil winding 2 more than necessary, and the coil winding 2 can be covered by the extension of the coil winding 2 or contact with the coil winding jig. It is possible to reduce the damage to the strands and to simplify the coil winding jig itself, which contributes to cost reduction of manufacturing equipment and yield improvement.

  Further, if the angle between the first inclined axis a and the base surface x is set to 60 degrees, for example, the stacking direction overlaps with a state shifted by ½ of the diameter of the coil winding 2, so The upper and lower coil windings 2 are arranged, and the finished height of the heating coil 1 is lower than that of a simple stack. As a result, the magnetic path length between the heating coil 1 and the load (pan) is shortened. As a result, the magnetic resistance is reduced, the magnetic lines generated from the heating coil 1 efficiently reach the load, and the heating efficiency is increased. .

  Moreover, it arrange | positions so that the coil winding 2 may contact, By this contact part, the intensity | strength as the heating coil 1 can be improved, a deformation | transformation and dropout can be prevented and it leads to the improvement of shape stability.

  In addition, by using a coating having heat self-fusing property on the coil winding 2 itself, it is possible to bond the Litz wires between the multi-layers by heat, and the shape of the heating coil 1 can be changed using an adhesive or a curing agent. There is no need to hold it, and it is possible to secure adhesion to other steps without spreading adhesives or hardeners on the unexposed part of the intermediate step part. A strength of 1 can be secured.

It is a longitudinal cross-sectional view which shows the relationship between the heating coil of an induction heating cooking appliance, and load. It is a longitudinal cross-sectional view of the heating coil for induction heating cookers which shows one Example of this invention. It is a detailed longitudinal cross-sectional view of the heating coil winding part in FIG. It is a detailed longitudinal cross-sectional view of the winding part of a heating coil with two stacking stages in FIG. It is a detailed longitudinal cross-sectional view of the winding part of a heating coil with two stacking stages according to the conventional winding method. It is a detailed longitudinal cross-sectional view of the winding part of the heating coil with three stacking stages concerning the other Example of this invention. It is explanatory drawing of intensity | strength ensuring of the heating coil of 2 steps | paragraphs in one Example of this invention, (a) is an angle of the 1st inclination angle, and (b) is the 1st inclination angle. This is the case where the angle is 60 degrees. It is explanatory drawing of intensity | strength ensuring of the heating coil of 3 steps | paragraphs of stacking stages, (a) is what arrange | positioned the conventional stacking steps number 3 steps and 2 steps alternately, (b) is the 1st in one Example of this invention. The angle of one inclination axis a is 60 degrees, and the number of stacking stages is three. It is explanatory drawing after the deformation | transformation operation of the finished shape in the other Example of this invention, (a) is a case where the coil winding 2 is wound with tension, (b) is a winding jig after winding This is a case where the force is applied to deform the cross section of the coil winding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating coil 2 Coil winding 3 Coil base a 1st inclination axis b 2nd inclination axis x Base surface y Winding center axis

Claims (4)

In induction cooking including a heating coil in which a plurality of coil windings are wound around the base surface around a central winding axis, the heating coil has an angle of greater than 0 degrees and less than 90 degrees with respect to the base surface. Having a first tilt axis and a second tilt axis symmetrical to the first tilt axis with respect to the winding center axis, each side on the first and second tilt axes being an equilateral side, And the induction heating cooking appliance by which the coil winding was arrange | positioned at each vertex of the substantially isosceles triangle which has one side on the surface parallel to a winding plane, and the said parallel moved triangle. 2. The induction heating cooker according to claim 1, wherein the heating coil is any one of n−1th and at least n−4th in a cross section of the nth winding except before and after the coil winding arrangement moving part. Induction heating cooker in contact with two coil windings. 3. The induction heating cooker according to claim 1, wherein the coil winding disposed on the bottom surface or the top surface of the heating coil wound in a disk shape is a coil winding except before and after the winding arrangement moving portion. An induction heating cooker having a portion that is in contact with a coil winding of the same winding plane adjacent to. 4. The induction heating cooker according to claim 1, wherein the coil winding has a self-fusing coating by heat.

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