JP7501211B2 - Induction Heating Equipment - Google Patents

Description

The present invention relates to an induction heating device.

In induction heating, the object to be heated, which is a conductive material such as a metal, is placed in the magnetic flux generated by a coil, and eddy currents are generated by electromagnetic induction, allowing for non-contact, fast, and highly efficient heating. In induction heating, the object to be heated may be placed inside the coil (see, for example, Patent Document 1). Since the coil is cylindrical, the object to be heated placed inside may also be cylindrical.

JP 2015-187954 A

Heated objects come in a variety of shapes other than a simple cylinder; for example, there are cylinders with some kind of protrusion on the outer periphery. The magnetic flux generated by the coil is transmitted along the cylinder, but a particularly large amount of magnetic flux is concentrated at the protrusion, causing localized overheating. It is possible to adjust the magnetic flux passing through the protrusion by placing a specialized magnetic material around the protrusion according to its shape, but this does not provide the versatility to accommodate various shapes of heated objects.

In addition, if the object to be heated is a non-magnetic material, it is necessary to pass a large current to increase the magnetic flux. In this case, the magnetic material used for adjustment will become magnetically saturated and will no longer function, and the coil will need to be water-cooled, making the device more complicated and expensive.

The present invention was made in consideration of the above problems, and aims to provide an induction heating device that is versatile enough to accommodate the shapes of various objects to be heated, and can be easily and inexpensively implemented.

In order to solve the above problems and achieve the object, the induction heating device of the present invention is characterized in that it comprises a coil in which an object to be heated is placed, and a first internal magnetic material that is placed between the inner circumferential surface of the coil and an outer peripheral protrusion of the object to be heated, and that the first internal magnetic material is configured so that its position can be adjusted in the circumferential and axial directions based on the coil.

By making the first internal magnetic material adjustable in both the circumferential and axial directions in this way, a simple and inexpensive structure can be achieved that is versatile enough to accommodate the shapes of various objects to be heated.

The first internal magnetic material may be composed of multiple elements with gaps in the axial direction. By providing gaps between the elements of the first internal magnetic material in this way, the magnetic resistance can be adjusted.

The first internal magnetic material may be ferrite, and the gap formed by the first internal magnetic material in the axial direction may be 0.3 mm to 1.5 mm. This can suppress magnetic saturation.

A plurality of external magnetic members may be provided outside the outer circumferential surface of the coil, arranged in the circumferential direction and extending in the axial direction. Such external magnetic members can reduce magnetic flux leakage to the outside.

The external magnetic material may be composed of multiple elements with gaps in the axial direction. By providing gaps between the elements of the external magnetic material in this way, the magnetic resistance can be adjusted.

The external magnetic material may be ferrite, and the gap that the external magnetic material forms in the axial direction may be 0.3 mm to 1.5 mm. This can suppress magnetic saturation.

A second internal magnetic material may be provided that is disposed between the inner circumferential surface of the coil and the axial end of the object to be heated or in its vicinity. Such a second internal magnetic material can prevent local overheating of the axial end of the object to be heated.

The device may include a plurality of plate members arranged in the circumferential direction between the inner circumferential surface of the coil and the object to be heated and detachable in the axial direction, and the first internal magnetic material may be fixed to one or more of the plate members. Such plate members are simple and inexpensive, and the first internal magnetic material can be easily fixed and its position adjusted.

The multiple plate materials may each have the same shape when viewed in the axial direction, and 8 to 12 of them may cover the heated object in the radial direction based on the coil. This allows for a moderate degree of freedom in position adjustment, and allows the inner heating chamber and the outer cooling chamber to be formed with appropriate areas.

The coil may be provided with an air-cooling device for cooling the coil, and an air guide duct formed so that the air flow from the air-cooling device is on the outer periphery side of the plate material. This allows the coil to be cooled efficiently. In addition, the air-cooling device is inexpensive and easy to handle.

The object to be heated may be a non-magnetic material.

The induction heating device of the present invention is versatile enough to accommodate the shapes of various objects to be heated, and can be easily and inexpensively implemented.

FIG. 1 is a side view of an induction heating device according to an embodiment of the present invention. FIG. 2 is a plan view of the induction heating device. FIG. 3 is a plan view of the induction heating device with the top plate removed. FIG. 4 is a cross-sectional side view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional plan view taken along line VV in FIG. FIG. 6 is a cross-sectional perspective view of the induction heating device cut at the mid-height. FIG. 7 is a diagram showing various examples of inner plates, where (a) is a diagram showing a first example of an inner plate, (b) is a diagram showing a second example of an inner plate, (c) is a diagram showing a third example of an inner plate, (d) is a diagram showing a fourth example of an inner plate, (e) is a diagram showing a fifth example of an inner plate, and (f) is a diagram showing a sixth example of an inner plate. FIG. 8 is a partially enlarged schematic cross-sectional side view of the induction heating device.

Below, an embodiment of an induction heating device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment.

Figure 1 is a side view of an induction heating device 10 according to an embodiment of the present invention. In Figure 1, the right half of the outer plate 28 has been omitted so that the interior can be viewed. Figure 2 is a plan view of the induction heating device 10. Figure 3 is a plan view of the induction heating device 10 with the upper plate 16 removed. Figure 4 is a cross-sectional side view taken along line IV-IV in Figure 3. Figure 5 is a cross-sectional plan view taken along line V-V in Figure 4. In the following description, the axis J of the coil 22 in the induction heating device 10 is used as a reference, the direction along the axis J is the axial direction, the direction of an arc centered on the axis J is the circumferential direction, and the direction perpendicular to the axis J is the radial direction.

The induction heating device 10 is a device that inductively heats the object to be heated 12. The object to be heated 12 that is cylindrical can be used with the induction heating device 10, but various objects other than a simple cylinder can be used. In the following example, an object to be heated has a tube portion 12a, a lid portion 12b, a first outer peripheral protrusion 12c, and a second outer peripheral protrusion 12d. The first outer peripheral protrusion 12c is a protrusion formed at approximately the midpoint of the outer peripheral surface of the tube portion 12a, and is slightly longer in the circumferential direction than in the axial direction (see FIG. 6). The second outer peripheral protrusion 12d is a protrusion formed on the opposite side of the first outer peripheral protrusion 12c, is smaller than the first outer peripheral protrusion 12c, and is slightly longer in the circumferential direction than in the axial direction (see FIG. 6).

The portion 12aa of the cylindrical portion 12a where the first outer peripheral projection 12c is formed is slightly thick, and the portion 12ab where the second outer peripheral projection 12d is formed is slightly thin (see FIG. 4). The induction heating device 10 is capable of heating both magnetic and non-magnetic materials as the object to be heated 12. In the following example, the object to be heated 12 is a non-magnetic material (e.g., copper or aluminum).

The induction heating device 10 comprises a base plate 14, an upper plate 16, a fan (air-cooling device) 18, a coil plate 20, a coil 22, ten inner plates (plate materials) 24, ten inner plate supports 26 supporting these inner plates 24, ten outer plates 28, ten outer plate supports 30 supporting these outer plates 28, a first internal magnetic material 32 and a second internal magnetic material 34 provided on the inner plates 24, and ten external magnetic materials 36.

The coil 22 is fixed to the coil plate 20 so that the axis J is vertical. The coil plate 20 is fixed slightly above the base plate 14. The coil 22 is composed of, for example, an upper coil 22a and a lower coil 22b. The upper coil 22a and the lower coil 22b are arranged, for example, in parallel in the axial direction. The upper coil 22a has a pair of terminals 22aa, and the lower coil 22b has a pair of terminals 22ba. The upper coil 22a and the lower coil 22b are connected in parallel to, for example, an inverter. A small gap 22c is provided between the upper coil 22a and the lower coil 22b, and the presence or absence of the heated object 12 inside can be detected from the gap 22c by a pair of optical sensors (not shown). The optical sensors are attached to a pair of brackets 37.

The ten inner plate supports 26 have slit grooves 26a formed on both circumferential sides, and each stands upward from the coil plate 20. The multiple inner plates 24 have the same shape at least when viewed in the axial direction. Specifically, the circumferential length of each inner plate 24 is equal to the interval between adjacent inner plate supports 26, and the thickness is approximately equal to the slit groove 26a. In this case, the axial length of each inner plate 24 is approximately equal to the height of each inner plate support 26. The ten inner plates 24 are inserted into the slit grooves 26a between the opposing surfaces of the adjacent inner plate supports 26, forming a regular decagon (see Figure 5). In other words, each inner plate 24 is provided within a range of 36 degrees based on the axis J.

Each inner plate 24 can be inserted and removed from above along the slit groove 26a. In other words, the inner plate 24 can be attached and removed in the axial direction. The inner plate 24 and the inner plate support 26 are provided inside the coil 22. The inner plate support 26 and the inner surface of the coil 22 are sufficiently close to or in contact with each other. An inner air guide passage 41 is provided between the inner surface of the coil 22 and the inner plate 24.

The inner plate 24 and the inner plate supports 26 are made of insulating heat-resistant resin material. The inside of the inner plate 24 and the inner plate supports 26 form a heating chamber 38. The object to be heated 12 is placed inside the coil 22 (specifically, inside the heating chamber 38) and is arranged approximately coaxially with the coil 22. The object to be heated 12 is placed at approximately the middle height inside the heating chamber 38, but may be slightly shifted in the axial direction depending on the conditions. The table on which the object to be heated 12 is placed is omitted in each figure. The object to be heated 12 can be inserted and removed from the upper opening 10a of the induction heating device 10.

Figure 6 is a cross-sectional perspective view of the induction heating device 10 cut at the mid-height. As shown in Figure 6, the ten inner plates 24 and inner plate supports 26 that form the heating chamber 38 radially cover the object to be heated 12.

Depending on the shape of the outer circumferential projection of the heated object 12, the first internal magnetic material 32 is fixed to one or more of the ten inner plates 24. Here, the inner plate 24 facing the relatively large first outer circumferential projection 12c is identified as the inner plate 24α, and the inner plate 24 facing the relatively small second outer circumferential projection 12d is identified as the inner plate 24β. The first internal magnetic material 32 is fixed to the inner plates 24α and 24β. The circumferential dimension of the first internal magnetic material 32 is set long enough not to interfere with the inner plate support 26, and almost covers the first outer circumferential projection 12c and the second outer circumferential projection 12d in the radial direction. If the circumferential dimensions of the first outer circumferential projection 12c and the second outer circumferential projection 12d are small, the circumferential dimension of the first internal magnetic material 32 should be adjusted accordingly.

Returning to FIG. 4, the first internal magnetic material 32 is set at approximately the midpoint height of the inner plates 24α, 24β in accordance with the axial positions of the first outer peripheral projection 12c and the second outer peripheral projection 12d.
That is, the first internal magnetic material 32 is disposed between the inner peripheral surface of the coil 22 and the outer peripheral protrusions 12c, 12d of the object to be heated 12. The first internal magnetic material 32 does not cover the outer peripheral protrusions 12c, 12d when viewed in the axial direction, and does not interfere with the insertion and removal of the object to be heated 12.

The first internal magnetic material 32 provided in the inner plate 24α is composed of three ferrite elements 32a, 32b, and 32c arranged in the axial direction. The first internal magnetic material 32 provided in the inner plate 24β is composed of two ferrite elements 32d and 32e adjacent to each other in the axial direction. The ferrite elements 32a to 32e are the same and are in the shape of a slightly elongated plate.

The magnetic flux Φ (see FIG. 8) generated by the coil 22 passes through the cylindrical portion 12a to generate heat, but the first outer peripheral protrusion 12c and the second outer peripheral protrusion 12d tend to have more magnetic flux Φ flowing through them the more they protrude, which can cause local overheating. In contrast, in this embodiment, the first internal magnetic material 32 is disposed between the inner circumferential surface of the coil 22 and the first outer peripheral protrusion 12c and the second outer peripheral protrusion 12d of the heated object 12, respectively, to form a bypass magnetic path for the magnetic flux Φ, and the magnetic flux Φ flowing through the first outer peripheral protrusion 12c and the second outer peripheral protrusion 12d is suppressed, thereby preventing local overheating.

As described above, the first internal magnetic material 32 facing the relatively large first outer peripheral protrusion 12c is composed of three ferrite elements 32a, 32b, and 32c, and the first internal magnetic material 32 facing the relatively small second outer peripheral protrusion 12d is composed of two ferrite elements 32d and 32e. The magnetic resistance of the bypass magnetic path is adjusted by increasing or decreasing the number of elements depending on the size of the protrusion.

Also, an axial gap G1 is formed between adjacent ferrite elements 32a-32c, and between ferrite elements 32d and 32e. In other words, the first internal magnetic material 32 is composed of ferrite elements 32a-32c with gaps in the axial direction. The first internal magnetic material 32 is composed of ferrite elements 32a-32e, not electromagnetic steel plates, and has a gap G1 in the direction in which the magnetic flux Φ passes, so that there is an appropriate magnetic resistance and heat generation is suppressed. For this reason, the first internal magnetic material 32 does not require water-cooling. According to the inventor's experiments and analysis, in order for the first internal magnetic material 32 to have an appropriate magnetic resistance, it is best to set the gap G1 to 0.3 mm-1.5 mm.

The second internal magnetic material 34 is disposed between the inner circumferential surface of the coil 22 and the axial end of the object 12 or its vicinity, depending on the type of the object 12. That is, if the axial end of the object 12 is thin, local overheating may occur, so the second internal magnetic material 34 is provided as necessary to bypass part of the magnetic flux Φ at this portion. In this embodiment, the second internal magnetic material 34 is provided near the lower end (axial end) 12e of the portion 12aa where the first outer peripheral projection 12c is formed, and near the lower end (axial end) 12f of the portion 12ab where the second outer peripheral projection 12d is formed.

Specifically, one of the second internal magnetic materials 34 (designated 34α in FIG. 4) is disposed between the lower end 12f and the inner surface of the coil 22, and the other second internal magnetic material 34 (designated 34β in FIG. 4) is disposed between the vicinity of the lower end 12e (slightly below) and the inner surface of the coil 22.

That is, since the portion 12ab is relatively thin, it is believed that local overheating is likely to occur at the lower end 12f, and the second internal magnetic material 34α is placed at an axial position facing the lower end 12f to enhance the bypass effect of the magnetic flux Φ. In contrast, since the portion 12aa is relatively thick, local overheating is less likely to occur at the lower end 12e compared to the lower end 12f, and the second internal magnetic material 34β is slightly shifted from the axial position facing the lower end 12e to slightly suppress the bypass effect of the magnetic flux Φ. On the other hand, the second internal magnetic material 34 is not provided near the upper end 12g of the heated object 12. This is because the lid portion 12b is provided above the heated object 12 and has a large heat capacity, so local overheating does not occur.

The second internal magnetic material 34 is fixed to the inner plate 24 in the same manner as the first internal magnetic material 32. The second internal magnetic material 34 is composed of two ferrite elements 34a, 34b adjacent to each other in the axial direction. The ferrite elements 34a, 34b are the same as the ferrite elements 32a to 32e described above. A gap G1 is formed between the ferrite elements 34a and 34b for the same reason as in the case of the first internal magnetic material 32 described above. In this case, the gap G1 should be set to 0.3 mm to 1.5 mm, similar to the case of the first internal magnetic material 32.

Figure 7 shows various examples of the inner plate 24, where (a) shows the first example of the inner plate 24a, (b) shows the second example of the inner plate 24b, (c) shows the third example of the inner plate 24c, (d) shows the fourth example of the inner plate 24d, (e) shows the fifth example of the inner plate 24e, and (f) shows the sixth example of the inner plate 24f. For simplicity, the second internal magnetic material 34 has been omitted from Figure 7.

Various types of inner plate 24 are available. Inner plate 24a in FIG. 7(a) is an example in which the first internal magnetic material 32 is not provided. Inner plate 24b in FIG. 7(b) is an example in which the first internal magnetic material 32 consisting of three ferrite elements 32a to 32c is provided at approximately the middle height, and corresponds to inner plate 24α described above. Inner plate 24c in FIG. 7(c) is an example in which the first internal magnetic material 32 consisting of two ferrite elements 32d, 32e is provided at approximately the middle height, and corresponds to inner plate 24β described above. Inner plate 24d in FIG. 7(d) is an example in which the first internal magnetic material 32 consisting of three ferrite elements 32a to 32c is provided at a position slightly higher than the middle. If you want to set the first internal magnetic material 32 at a position slightly lower than the middle, you can use the inner plate 24d upside down. Inner plate 24e in FIG. 7(e) is the one in which the circumferential width of first internal magnetic material 32 in inner plate 24b is narrowed. This inner plate 24e is applied when the circumferential width of the outer peripheral protrusion in the heated object 12 is short. Inner plate 24f in FIG. 7(f) is the one in which the circumferential width of first internal magnetic material 32 in inner plate 24b is narrowed and the axial length is long. This inner plate 24f is applied when the circumferential width of the outer peripheral protrusion in the heated object 12 is short and long in the axial direction.

By appropriately selecting such inner plates 24a-24f, the position of the first internal magnetic material 32 can be adjusted in the circumferential and axial directions according to the position and size of the outer peripheral protrusions on the heated object 12. Therefore, the induction heating device 10 has versatility that can accommodate various shapes of the heated object 12. Furthermore, these inner plates 24 can be easily and inexpensively produced, and the cost burden is small even if a certain number of them are prepared. Furthermore, each inner plate 24 is thin and lightweight, and easy to handle. Each inner plate 24 can be easily attached and detached along the slit groove 26a. The axial length of each inner plate 24 may be set short so that multiple plates of different types can be arranged in the axial direction.

When the inner plates 24b to 24f are inserted axially along the slit grooves 26a, the first internal magnetic material 32 faces inward. By facing the first internal magnetic material 32 inward, it approaches the outer peripheral protrusions of the object to be heated 12, improving the bypass effect of the magnetic path. In addition, the inner air guide path 41 on the outside of the inner plate 24 is not blocked by the first internal magnetic material 32. If the object to be heated 12 does not have protrusions on its outer peripheral surface, it is possible to use only the inner plate 24a without the first internal magnetic material 32.

Placing a large number of inner plates 24 inside the coil 22 increases the degree of freedom in adjustment, but the configuration becomes complicated, there is some distance between the outer periphery of the heated object 12, and the inner air guide passage 41 becomes narrow. On the other hand, reducing the number of inner plates 24 reduces the degree of freedom in adjustment according to the heated object 12 and narrows the heating chamber 38. For this reason, it is appropriate to provide 8 to 12 inner plates 24, and more preferably 10 as in this embodiment.

Returning to Figures 1 to 5, the ten shell struts 30 have slit grooves 30a formed on both circumferential sides, and each stands upward from the base plate 14. The ten shell plates 28 are all of the same shape. Specifically, the circumferential length of each shell plate 28 is equal to the distance between adjacent shell struts 30, and the thickness is approximately equal to the slit grooves 30a. The axial length of each shell plate 28 is approximately equal to the height of each shell strut 30. The ten inner plates 24 are inserted into the slit grooves 30a between the opposing surfaces of the adjacent shell struts 30, forming a regular decagon (see Figure 5). In other words, each shell plate 28 is provided within a range of 36 degrees with respect to the axis J.

Each outer plate 28 can be inserted and removed from above along the slit groove 30a, but is usually fixed. The outer plate 28 and the outer plate support 30 are provided on the outside of the coil 22. There is an appropriate distance between the outer plate support 30 and the outer surface of the coil 22. The outer plate 28 and the outer plate support 30 are made of an insulating heat-resistant resin material. The inside of the outer plate 28 and the outer plate support 30 and the outside of the inner plate 24 and the inner plate support 26 form a cooling chamber 40. The coil 22 is arranged in the cooling chamber 40. An outer air guide passage 42 is formed between the outer surface of the coil 22 and the outer plate 28. The above-mentioned inner air guide passage 41 is part of the cooling chamber 40.

The ten external magnetic members 36 are arranged at equal intervals in the circumferential direction, and each member is composed of six ferrite elements 36a, 36b, 36c, 36d, 36e, and 36f. The bottom ferrite element 36a is arranged radially on the base plate 14. The four ferrite elements 36b to 36e are fixed to the inner surface of the outer plate support 30 and are arranged to extend in the axial direction. The top ferrite element 36f is fixed to the lower surface of the upper plate 16 and arranged radially. The ferrite elements 36a and 36f are the same member, but the former is arranged vertically and the latter is arranged horizontally. By arranging the ferrite elements 36a vertically, the area of the ventilation holes 14a described later can be made large.

A gap G2 is formed between adjacent ferrite elements 36a to 36f. In other words, the external magnetic material 36 is composed of ferrite elements 36a to 36f with gap G2 in the direction in which the magnetic flux Φ passes. Among these, the gap G2 between ferrite elements 36b to 36e is formed in the axial direction. A magnetic path for the magnetic flux Φ generated by the coil 22 is formed in the external magnetic material 36, so that leakage magnetic flux to the outside can be reduced. The external magnetic material 36 is composed of ferrite elements 36a to 36f, not electromagnetic steel sheets, and the gap G2 is formed in the direction in which the magnetic flux Φ passes, so that there is an appropriate magnetic resistance and heat generation is suppressed. For this reason, the external magnetic material 36 does not require water-cooling. According to the experiments and analysis of the present inventor, in order for the external magnetic material 36 to have an appropriate magnetic resistance, it is recommended to set the gap G2 to 0.3 mm to 1.5 mm.

Although it is possible to reduce leakage magnetic flux to the outside by arranging a large number of external magnetic materials 36 around the induction heating device 10, the configuration becomes complicated, and if there are few of them, the leakage magnetic flux increases. Therefore, it is appropriate to provide 8 to 12 external magnetic materials 36 at equal intervals, and more preferably 10 as in this embodiment. The number of inner plate supports 26 and outer plate supports 30 is the same, and they are arranged on the same line with respect to the axis J, forming a radial shape. Similarly, the number of inner plates 24 and outer plates 28 is the same and arranged radially, resulting in a well-balanced structure.

Each of the ferrite elements constituting the first internal magnetic material 32, the second internal magnetic material 34, and the external magnetic material 36 is a rectangular parallelepiped and can be selected, for example, from general-purpose products.

As shown in FIG. 2, the upper plate 16 has a central hole 16a and ten ventilation holes 16b arranged at equal intervals around the central hole. The central hole 16a is connected to the heating chamber 38 and constitutes the upper opening 10a of the entire device. The central hole 16a is large enough to insert the object to be heated 12. The inner diameter side end of the central hole 16a lightly abuts the upper surfaces of the inner plate 24 and the inner plate support 26 in a plan view, fixing them. When replacing the inner plate 24, the upper plate 16 is temporarily removed (see FIG. 3), but the central hole 16a may be made slightly larger so that the inner plate 24 can be replaced while the upper plate 16 is attached. The outer diameter side end of the central hole 16a lightly abuts the upper surfaces of the outer plate 28 and the outer plate support 30 in a plan view, fixing them.

The 10 ventilation holes 16b are formed in the middle of the 10 external magnetic materials 36. A thin bridge 16c between adjacent ventilation holes 16b lightly abuts the upper surface of the external magnetic material 36 to fix the external magnetic material 36. The ventilation holes 16b communicate with the cooling chamber 40. A filter may be provided in the ventilation holes 16b.

As shown in FIG. 6, the base plate 14 has ten ventilation holes 14a arranged radially. The ventilation holes 14a have the same shape as the ventilation holes 16b of the upper plate 16, and are arranged in the same manner in a plan view. The ten ventilation holes 14a are each formed in the middle of the ten external magnetic materials 36. Thin bridges 14b between adjacent ventilation holes 14a abut against the lower surface of the external magnetic material 36, supporting the external magnetic material 36. The ventilation holes 14a are connected to the cooling chamber 40.

As shown in FIG. 4, the coil plate 20 closes the bottom of the heating chamber 38. The cooling chamber 40 opens at the top through the ventilation hole 16b in the top plate 16 and at the bottom through the ventilation hole 14a in the base plate 14. A fan 18 is disposed below the base plate 14 and exhausts the air in the cooling chamber 40 downward.

Next, the operation of the induction heating device 10 will be described. Figure 8 is a partially enlarged schematic cross-sectional side view of the induction heating device 10. Figure 8 shows the left half of the induction heating device 10, but the right half or the direction perpendicular to the paper surface will of course have the same operation.

As shown in FIG. 8, when a high-frequency alternating current is passed through the coil 22, an alternating magnetic flux Φ is generated. At a certain time, the magnetic flux Φ circulates counterclockwise in FIG. 8, but clockwise circulation has the same effect. Within the heating chamber 38, the branch magnetic flux Φ1, which is the majority of the magnetic flux Φ, passes through the cylindrical portion 12a of the object to be heated 12 and heats the object to be heated 12 due to the effect of eddy currents. The other branch magnetic flux Φ2 passes through the outside of the cylindrical portion 12a, but when passing near the lower end 12e, it passes through the inside of the second internal magnetic material 34, or its course is corrected to the outside by the second internal magnetic material 34. Therefore, the branch magnetic flux Φ2 bypasses the lower end 12e, preventing local overheating of the lower end 12e.

The branch magnetic flux Φ2 that passes near the lower end 12e flows upward and branches into two branch magnetic fluxes Φ21 and Φ22. One branch magnetic flux Φ21 passes through the first outer peripheral projection 12c and heats the first outer peripheral projection 12c. The other branch magnetic flux Φ22 passes through the first internal magnetic material 32. In other words, the branch magnetic flux Φ22, which is a part of the branch magnetic flux Φ2, is bypassed by the first internal magnetic material 32, so that the branch magnetic flux Φ21 passing through the first outer peripheral projection 12c is suppressed, and local overheating of the first outer peripheral projection 12c is prevented. As described above, the ratio of the branch magnetic flux Φ21 to the branch magnetic flux Φ22 can be adjusted by the number of ferrite elements that make up the first internal magnetic material 32 and the gap G1.

The branched magnetic fluxes Φ1, Φ21, and Φ22 gather upward, become magnetic flux Φ again, and are introduced into the external magnetic material 36. The magnetic flux Φ passes through the external magnetic material 36 and travels downward before re-entering the heating chamber 38 and circulating. Since most of the magnetic flux Φ passes through the external magnetic material 36, leakage magnetic flux to the outside of the induction heating device 10 can be suppressed. Since gaps G2 are formed between the ferrite elements 36a to 36f in the external magnetic material 36, the magnetic resistance is appropriately adjusted and there is no excessive temperature rise.

The magnetic flux Φ shown in FIG. 8 is shown diagrammatically to facilitate understanding of the invention, and it goes without saying that the actual magnetic flux Φ does not have to be generated exactly as shown. It also goes without saying that in reality, each branch magnetic flux is not clearly distinguishable as shown in the figure.

Meanwhile, air cooling is performed by the fan 18 in the cooling chamber 40 of the induction heating device 10. That is, air introduced from the upper ventilation hole 16b passes through the cooling chamber 40 and the lower ventilation hole 14a, and is exhausted to the outside by the fan 18.

Since the cooling chamber 40 is a space partitioned by the inner plate 24 and the outer plate 28, air flows within a range that is more outer than the inner plate 24 and more inner than the outer plate 28. Specifically, air flows in a first flow path F1 that passes from the ventilation hole 16b through the inner air guide path 41 and the ventilation hole 14a, and in a second flow path F2 that passes from the ventilation hole 16b through the outer air guide path 42 and the ventilation hole 14a. The inner air guide path 41 and the outer air guide path 42 are formed so as to be at least more outer than the inner plate 24, and therefore do not directly cool the inside of the heating chamber 38.

The air flow through the first flow path F1 cools the inner surface of the coil 22 and also cools the first internal magnetic material 32 and the second internal magnetic material 34 through the inner plate 24. The air flow through the second flow path F2 cools the outer surface of the coil 22 and also cools the external magnetic material 36.

If the object 12 to be heated is a non-magnetic material, for example, when it is heated for shrink fitting, a considerable amount of power would be required. In the induction heating device 10, local overheating does not occur in the first outer peripheral protrusion 12c, the second outer peripheral protrusion 12d, the lower end 12e, 21g, etc., so heating can be performed without suppressing power. In addition, the magnetic resistance of the first internal magnetic material 32, the second internal magnetic material 34, and the external magnetic material 36 is appropriately adjusted, so there is no excessive temperature rise. Therefore, the induction heating device 10 can apply an air-cooling system using a fan 18 that is simple, low-cost, and easy to handle, rather than a complex and expensive water-cooling system. In the induction heating device 10, the first flow path F1 and the second flow path F2 are effectively arranged, and the coil 22, the first internal magnetic material 32, the second internal magnetic material 34, and the external magnetic material 36 can be efficiently cooled with a simple configuration.

The coil 22 can suppress heat generation by forming multiple layers in the radial direction while reducing the current by winding many conductors and connecting the inner layer side and the outer total ring in parallel to increase the total cross-sectional area of the conductors. The inner layer side and outer layer side parts are forced air-cooled inside and out by the first flow path F1 and the second flow path F2 described above, which can further suppress heat generation. Even if the voltage is increased instead of the current is increased, the coil 22 can be divided into an upper coil 22a and a lower coil 22b, and heat generation can be suppressed by passing electricity so that the voltage changes from the upper and lower ends toward the center.

The present invention is not limited to the above-described embodiment, and can of course be freely modified without departing from the spirit of the present invention.

10 induction heating device 12 object to be heated 12a cylindrical portion 12c first outer peripheral protrusion 12d second outer peripheral protrusion 14 base plate 14a, 16b ventilation hole 16 upper plate 16a central hole 18 fan (air-cooling device)
20 coil plate 22 coils 24, 24a to 24f, 24α, 24β inner plate (plate material)
26: Inner plate support 26a, 30a: Slit groove 28: Outer plate 30: Outer plate support 32: First inner magnetic material 32a to 32e, 34a, 34b, 36a to 36f: Ferrite element (element)
34, 34α, 34β Second inner magnetic material 36 Outer magnetic material 38 Heating chamber 40 Cooling chamber 41 Inner air guide passage (air guide passage)
42 Outer air duct (air duct)
F1 First flow path F2 Second flow paths G1, G2 Gap J Axis Φ Magnetic flux Φ1, Φ2, Φ21, Φ22 Branch magnetic flux

Claims (11)

A coil in which an object to be heated is placed;
A first internal magnetic material disposed between an inner peripheral surface of the coil and an outer peripheral protrusion of the same material on the heated object;
Equipped with
the first internal magnetic material is located on the outer circumferential side of the outer circumferential end of the outer circumferential projection,
An induction heating device, characterized in that the first internal magnetic material is configured so that its position can be adjusted in the circumferential and axial directions based on the coil. The induction heating device according to claim 1, characterized in that the first internal magnetic material is composed of multiple elements with gaps in the axial direction. The induction heating device according to claim 2, characterized in that the first internal magnetic material is ferrite, and the gap formed by the first internal magnetic material in the axial direction is 0.3 mm to 1.5 mm. The induction heating device according to any one of claims 1 to 3, characterized in that it is provided with a plurality of external magnetic members arranged in the circumferential direction and extending in the axial direction outside the outer circumferential surface of the coil. The induction heating device according to claim 4, characterized in that the external magnetic material is composed of multiple elements with gaps in the axial direction. The induction heating device according to claim 5, characterized in that the external magnetic material is ferrite, and the gap formed by the external magnetic material in the axial direction is 0.3 mm to 1.5 mm. The induction heating device according to any one of claims 1 to 6, characterized in that it comprises a second internal magnetic material disposed between the inner circumferential surface of the coil and the axial end of the object to be heated or in its vicinity. A plurality of plate members are arranged in the circumferential direction between the inner circumferential surface of the coil and the object to be heated and are detachable in the axial direction,
8. The induction heating device according to claim 1, wherein the first internal magnetic material is fixed to one or more of the plate materials. The induction heating device according to claim 8, characterized in that the multiple plate materials each have the same shape when viewed in the axial direction, and 8 to 12 of them cover the heated object in the radial direction based on the coil. an air-cooling device for cooling the coil;
an air guide path formed so that the air flow from the air-cooling device is on the outer periphery side of the plate material;
10. The induction heating device according to claim 8 or 9, further comprising: The induction heating device according to any one of claims 1 to 10, characterized in that the object to be heated is a non-magnetic material.

Images