JP2005085698A - Electric heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric heater, reducing the size of a mounting part of a side case in thickness direction. <P>SOLUTION: The electric heater comprises a heat emitting fin 32, a heating element for heating by energizing, and a heating body 3 formed by laminating an electrode plate 31 for applying power to the heating element. A heated body passes near the radiator fin 32 from a surface defined by the both end surfaces in laminating direction of the heating body and both side surfaces crossing the both end surfaces, towards other surface. A frame-shaped frame is arranged on outer periphery of the heating body 3. Side cases 23, 24 are arranged on outer side of the both end surface of the frame-shaped frame. Inner opposite surfaces 230, 248 of each side case 23, 24, facing the frame-shaped frame have engaging pieces 235, 245 projecting towards the frame-shaped frame and engaging to the frame-shaped frame. The engaging pieces 235, 245 of each side case 23, 24 are introduced from the side surface of the frame-shaped frame to an inner part of the frame-shaped frame and engaged to the frame-shaped frame in the inner part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric heater that employs a positive temperature coefficient thermistor or the like as a heating element.

  As shown in FIGS. 16 to 19, a pair of first and second holding frames 91 and 92 arranged substantially parallel to each other, orthogonal to the first and second holding frames 91 and 92, and first and second The electric heater 9 is held by the side frames 95 arranged at both ends of the holding frames 91 and 92, and the heating element 3 is arranged in a plane formed by the first, 291st and 92nd and side frames 95. Are known.

The heating element 3 is formed by stacking heat radiation fins 32, heat generating elements, and electrode plates 31 for applying electric power to the heat generating elements substantially parallel to each other. The first and second holding frames 91 and 92 are substantially perpendicular to the stacking direction of the heating elements 3, and the side frames 95 are approximately parallel to the stacking direction.
As shown in FIGS. 17 and 18, the first holding frame 91 is configured by stacking two cylindrical members 901 and 902, and the inner cylindrical member 902 is provided with a cut in the surface on the heating element 3 side. A spring material is formed by forming a cut piece and raising the cut piece. Although not shown, the second holding frame 92 has the same configuration.

As shown in FIGS. 17 and 19, an L-shaped notch is provided in the side end 911 of the outer cylindrical member 901, and the end inner surface 951 of the side frame 95 is fitted into the L-shaped notch. The side L frame 95 is fixed to the first and second holding frames 91 and 92 by providing the inverted L-shaped protrusions 951 and fitting them together.
This fixing is performed by compressing the spring material 903 existing between the first and second holding frames 91, 92 and the heating element 3 by applying a force from the stacking direction of the heating elements 3, while This is realized by hooking the inverted L-shaped projecting portion 951 on the side end portions 911 of the first and second holding frames 91 and 92.
In addition, since the side part frame on the left side of the drawing in FIG.

Then, side cases 93 and 94 are placed from outside the side surface of the side frame 95 to protect the heating element 3, take out the electrode plate 31, and insulate. It should be noted that another case 945 is placed on the outer side of the side case 94.
The structure mentioned above is a structure known also in the field | areas of a radiator etc. which are shown by the cited reference 1 other than an electric heater.

Japanese Patent No. 3274234

By the way, recently there is a great demand for compact electric heaters. This demand is particularly remarkable in the field of electric heaters for vehicles.
However, in the conventional configuration according to FIGS. 16 to 19 described above, the side cases 93 and 94 are simply covered from the outside of the side frame 95, so that the side cases 93 and 94 are held by the first and second holding portions. From the surface of the frames 91 and 92 and the side frame 95, it jumps out in the thickness direction.
Consider the case where an electric heater is attached to the air conditioning duct of a vehicle. Since the air conditioner duct is formed of a curved surface, there are many restrictions on the installation space of the opening for feeding the electric heater. For this reason, it is desirable that the vicinity of the attachment portion of the side case is compact in the thickness direction, and the portion protruding from the surface of the heating element is small or not.
Of course, if the thickness of the side cases 93 and 94 is reduced, the protruding portion can be reduced. However, considering the decrease in mechanical strength, ease of manufacture, and ease of installation of the side cases 93 and 94, Using a thin case is not a preferred choice.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an electric heater in which the side case mounting portion is compact in the thickness direction.

The present invention has a heat generating element formed by laminating a heat dissipating fin, a heat generating element that generates heat when energized, and an electrode plate that applies power to the heat generating element. An electric heater in which a medium to be heated passes through the vicinity of the radiating fin from one surface stretched by both side surfaces to the other surface,
A frame-like frame is provided on the outer periphery of the heating element,
Provide side cases on the outside of both sides of the frame-shaped frame,
The inner facing surface of each side case facing the frame-like frame has an engagement piece that protrudes toward the frame-like frame and engages with the frame-like frame,
An engagement piece of each side case is introduced into the inside of the frame-like frame from the side surface of the frame-like frame, and is engaged with the frame-like frame inside. 1).

  The electric heater according to the present invention is provided with a side case from the outside of the side surface of the frame-shaped frame provided on the outer periphery of the heating element, and the engagement piece provided on the side case is used to engage the frame-shaped frame. Match. At this time, the case is not put on the outer surface of the frame-shaped frame and engaged on the outer surface (see FIG. 16 described in the prior art), but as shown in FIGS. An engagement piece is introduced into the interior of the frame, and engagement is performed within the frame-shaped frame.

As shown in FIG. 16 described as the prior art, the electric heater configured to cover the inside of the side case so as to accommodate the frame-like frame is protruded outward from the surface of the frame-like frame. The thickness in the vicinity of the attachment position of the side case increases by the amount of protrusion.
The thickness referred to here means that the medium to be heated is located near the heat dissipating fin from one surface stretched by both end surfaces in the stacking direction of the heating element and both side surfaces intersecting the both end surfaces. It is the length along the direction when passing.

In contrast to the prior art, the electric heater according to the present invention, for example, as shown in FIGS. 1 and 2 to be described later, introduces an engagement piece provided in the side case into the inside of the frame-like frame. Engages with the frame-like frame internally.
Therefore, it is possible to attach the side case so that it does not jump out or protrude from the surface of the frame-like frame, and a compact electric heater is obtained in the thickness direction near the attachment position of the side case from the conventional configuration. Thus, the installation space of the opening of the air conditioner duct into which the electric heater is inserted can be reduced, and the mountability of the electric heater can be improved.
As mentioned above, according to this invention, the electric heater which made the side case attachment part compact in the thickness direction can be provided.

  The electric heater of the present invention can use a PTC (Positive Temperature Coefficient) element as a heating element. A PTC element has a property that electrical resistance rapidly increases above a specific temperature. Therefore, it generates heat when energized. However, when the temperature at which heat is generated exceeds a predetermined temperature, the electrical resistance becomes too high and almost no current is generated. It will not flow and will not generate heat to a certain degree of temperature. Therefore, it is possible to prevent overheating of the heater by using this element.

In the electric heater according to the present invention, the frame-like frame is assembled so as to hold the outer periphery of the heating element. The said side case is arrange | positioned with respect to the side surface of the assembly which assembled | attached the frame-shaped frame to the heat generating body. In this case, as a form of the side case, there is a side case having substantially the same shape as a side surface of an assembly in which a frame-like frame is assembled to a heating element, as in a side case 23 shown in FIG.
In addition, there is a side case 24 that is larger than the side surface of the assembly and has a flange that protrudes in the stacking direction of the heating elements, such as a side case 24 shown in FIG. 1 described later.
In the case of the side case 24, the thickness of the collar portion is larger than the thickness of the electric heater, but the portion attached to the side frame where the side case 24 is a frame-shaped frame does not protrude and has a compact configuration. (See the right side of FIG. 2B).

Next, the frame-shaped frame includes first and second holding frames provided on both end surfaces in the stacking direction of the heating element, and side frames provided on both side surfaces of the heating element, respectively.
Each side case is provided so as to cover the outer side surface of the heating element together with the side frame from the outer side surface of the side frame, and preferably engages with the first and second holding frames. (Claim 2).
By configuring the frame-shaped frame from the first and second holding frames and a pair of side frames provided on both side surfaces, the assembly of the frames to the heating element can be facilitated.
Further, by providing a side case from the outside of the side surface of the side frame and engaging the side case with the first and second holding frames, the side frame can be prevented from falling off.

Next, in the electric heater, when the length along the passing direction of the medium to be heated is a thickness, the thickness d1 of the side case is d1 compared with the thickness d2 of the first and second holding frames. It is preferable that ≦ d2 (claim 3).
Accordingly, when the side cases are attached to the first and second holding frames, the side cases do not protrude in the thickness direction from these frames. (Here, it is the portion where the side case and each holding frame are in contact that does not jump out. Some side cases have a flange as shown in FIG. (It is provided to jump out from the body and each holding frame.)
When the electric heater according to such a configuration is used by being inserted into an air conditioner duct or the like, the mounting space of the opening of the air conditioner duct can be reduced, so that the mountability of the electric heater is improved. Can do.

Next, the first and second holding frames are formed of cylindrical members having openings on both side surfaces, and can be engaged with the engagement pieces, and are stretched by both end surfaces and both side surfaces of the heating element. Having an engagement hole opening in the surface,
It is preferable that the engagement piece of the side case is inserted into the opening, and the engagement piece is engaged with the engagement hole from the inner surface of the first and second holding frames. .
Thereby, the engagement between the side case and the first and second holding frames can be strengthened, and the engagement pieces of the side case can be easily inserted into the first and second holding frames. Can do.

(Example 1)
As shown in FIGS. 1 to 15, the electric heater 1 according to this example includes a radiation fin 32, a heating element 330 that generates heat when energized, an electrode plate 31 that applies power to the heating element 330, first and second insulations. The heating element 3 is formed by laminating the bodies 391 and 392, and is stretched by both end surfaces 301 and 302 in the stacking direction of the heating element 3 and both side surfaces 303 and 304 intersecting the both end surfaces 301 and 302. The medium to be heated passes from the surface 305 toward the other surface 306 in the vicinity of the heat radiating fins 32.

  As shown in FIG. 1, a frame-like frame is provided on the outer periphery of the heating element 3, side cases 23 and 24 are provided on the outer sides of the both sides of the frame-like frame, and each side part facing the frame-like frame is provided. The inner facing surfaces 230 and 248 of the cases 23 and 24 protrude toward the frame-shaped frame and have engagement pieces 235 and 245 that engage with the frame-shaped frame. The pieces 235 and 245 engage with each other inside the frame-shaped frame.

The frame-shaped frame includes first and second holding frames 21 and 22 provided on both end surfaces of the heating element 3 in the stacking direction, and two side frames 1 provided on both side surfaces 303 and 304 of the heating element 3, respectively. It consists of.
The side case 23 is provided so as to cover the outer side surface of the heating element 3 together with the side frame 1 from the outer side surface of the left side frame 1, and the first and second holding frames 21, 22. Engage with. The side case 24 is similarly provided from the outside of the side surface of the right side frame 1.
The first and second holding frames 21 and 22 are made of cylindrical members having openings 213, 214, 223, and 224 provided on both side surfaces, and can be engaged with the engagement pieces 235 and 245. The body 3 has engagement holes 217, 218, 227, and 228 that open toward the surfaces stretched by both end surfaces and both side surfaces.
The engaging pieces 235 and 245 of the side cases 23 and 24 are inserted into the openings 213, 214, 223 and 224, and the engaging pieces 235 are inserted from the inner surfaces of the first and second holding frames 21 and 22. 245 is engaged with the engagement holes 217, 218, 227, and 228.

Details will be described below.
In the electric heater 2 of this example, as shown in FIG. 3, the heat of the heating element 330 is conducted to the radiation fin 32, and the medium to be heated (for example, air) passes from the surface 305 of the heating element 3 toward the surface 306. In doing so, heat is received from the radiation fins 32, and the temperature of the medium to be heated rises.
As shown in FIGS. 1 to 3, the heating element 3 includes a first insulator 391, an electrode plate 31, a radiation fin 32, a holder 33 that holds a heating element 330, an electrode plate 31, a radiation fin 32. 32 and the second insulator 392 are stacked in this order, and include four electrode plates 31, five radiating fins 32, and four holders 33 that hold four heating elements 330.
The side frames 1 are arranged on the left and right side surfaces 303 and 304 of the heating element 3, and the side cases 23 and 24 are arranged outside the side frames 1.

  As shown in FIGS. 1 and 2, the radiating fin 32 is composed of two L-shaped frames 321 and 322 and a thin corrugated plate 320, and has a rectangular shape surrounded by the two L-shaped frames 321 and 322. The corrugated plate 320 is accommodated in a space. The L-shaped frames 321 and 322 and the corrugated plate 320 are integrated by brazing. Here, each of the L-shaped frames 321 and 322 and the corrugated plate 320 is made of aluminum.

The heating element 330 is composed of a barium titanate ceramic semiconductor PTC element.
As shown in FIGS. 1 and 5 to 7, the holder 33 that holds the heat generating element 330 includes a main body 331, a side end protrusion 333 that protrudes from one side end of the main body 331, and the other side end. And a terminal protrusion 334 for guiding a connection terminal 311 provided on the electrode plate 31 described later. The side end protrusion 333 and the terminal protrusion 334 are configured to be narrower than the main body 331. The bottom surface of the main body 331 has four holding holes 332 for holding the heat generating element 300.
As shown in FIG. 7, the holder 33 has an H-shaped cross section, and both sides of the heating element 3 in the stacking direction are groove-shaped. By using the groove shape, the heat radiation fins 32, the electrode plates 31, and the holders 33 adjacent to each other in the stacking direction can be held so as not to jump out in the direction of the surfaces 305 and 306.
The electrode plate 31 is made of a long and thin flat metal plate, and has a terminal portion 311 to which a female terminal 261 described later can be connected at one end. The electrode plate 31 is made of brass.

As shown in FIG. 1, the first insulator 391 insulates the electrode plate 31 located at the extreme end of the heating element 3 from the first holding frame 21. The second insulator 392 insulates between the heat radiating fins 32 located at the extreme end of the heating element 3 and the second holding frame 22. The first insulator 391 is a groove type that can hold the electrode plate 31. The second insulator 392 is a groove type that can hold the radiation fins 32.
As shown in FIGS. 1 to 3, the first and second holding frames 21, 22 are hollow cylindrical members having a square cross section, and openings 213, 223 toward the side surface 303 of the heating element 3 and openings toward the side surface 304. 214 and 224, and engaging holes 217, 218, 227, and 228 that engage with engaging pieces 235 and 245 of side cases 23 and 24, which will be described later, at both ends in the longitudinal direction.

Further, as shown in FIG. 4, the side frame 1 constituting the frame-shaped frame of the present example has a substantially U-shaped cross section and includes first and second fixing pieces 11 and 12 and an annular support portion 10. The first fixed piece 11 includes a proximal end portion 111 and a distal end portion 113, and a bent portion 112 having a V-shaped cross section therebetween. Similarly, the second fixed piece 12 includes a proximal end portion 121 and a distal end portion 123, and a bent portion 122 having a V-shaped cross section therebetween.
The side frame 1 is composed of SK5, which is spring steel, and the entire member functions as a spring.
The base end portions 111 and 121 extend from both ends of the support portion 10 in a gentle curve shape, and the tip end portions 113 and 123 are members that extend linearly. The first and second fixed pieces 11 and 12 are bent into a square shape at the boundary between the base end portions 111 and 121 and the distal end portions 113 and 123, and the bent portions are the bent portions 112 and 122.

The side cases 23 and 24 made of 66 nylon and disposed outside the side frame 1 will be described.
As shown in FIGS. 8 to 10, the side case 23 located on the left side of FIG. 1 has a rectangular side surface shape and has four engagement pieces 235 extending on the side frame 1 side on the inner facing surface 230. The engagement piece 235 engages with engagement holes 217 and 227 located on the left side of the first and second holding frames 21 and 22 in the drawing.
The engagement piece 235 includes a main body piece 236 and a claw portion 237 formed to protrude from the tip of the main body piece 236. The claw portion 237 has a hook shape and engages with the engagement holes 217 and 227 at the hook portion. Further, the first and second holding frames 21 and 22 have engagement holes on the surface 306 side shown in FIG. 3, but the description is omitted because they are invisible from the drawing.

Further, as shown in FIG. 2B, in the electric heater 2, when the length along the passing direction of the medium to be heated is a thickness, the thickness d1 of the side case 23 is a frame-like case on the heating element 3. The thickness of the assembly formed by assembling the first and second holding frames 21 and 22 and the side frame 1 is smaller.
Here, the thickest part in the thickness of the assembly is the thickness d2 of the first holding frame 21, and d1 <d2 in the electric heater 2 according to this example.

As shown in FIGS. 11 to 13, the right side case 24 of FIG. 1 has a main body portion 242 and a flange portion 241 projecting outward from the main body portion 242. There are four engagement pieces 245 extending to the side frame 1 side, and the inner facing surface 248 penetrates the side case 24 and the terminal portion 311 of the electrode plate 31 is inserted to the outside. It has an insertion groove 249 for drawing out. Further, a terminal slit 240 for inserting the female terminal 261 connected to the terminal portion 311 is provided on the outer side of the heating element 3.
The engaging piece 245 includes a main body piece 246 and a claw portion 247 formed to protrude from the tip of the main body piece 246. The claw portion 247 has a hook shape, and the hook portion engages with the engagement holes 218 and 228. When engaged, the flange portion 241 protrudes greatly from the surfaces of the heating element 3 and the first and second holding frames 21 and 22, but the main body portion 242 extends from the surfaces of the first and second holding frames 21 and 22. The shape will not pop out.
In addition, the female terminal 261 is inserted, and a protective case 25 for covering and storing the female terminal 261 from outside the side case 24 is provided.
A lead wire 262 extending from the female terminal 261 has sockets 263 and 264 that are connected to an external power source (not shown) of the electric heater 2.

The assembly of the electric heater 2 of this example will be described.
As shown in FIG. 1, the heating element 330 is incorporated in the holder 33, and the first insulator 391, the electrode plate 31, the radiation fin 32, the holder 33 holding the heating element 330, the electrode plate 31, the radiation fin 32. The heat dissipating fins 32 and the second insulator 392 are stacked in this order.
At this time, since the holder 33 and the first and second insulators 391 and 392 are configured in a groove shape, the holder 33 and the first and second insulators 391 and 392 are adjacent to the radiation fins 32 and the like. The electrode plate 31 can be held to stabilize the laminated state of the heating element 3.
Next, as shown in FIGS. 14 (a) and 14 (b), the bending portions 112 and 122 of the first and second holding frames 21 and 22 are more than the distance L1 between the inner side surfaces 219 and 229 on the heating element 3 side. The side frame 1 is deformed so that the distance L0 is increased.

  As shown in FIG. 14 (b), the first and second fixing pieces 11, 12 of the deformed side frame 1 are opened from the side surfaces 303, 304 of the heating element 3 to the openings of the first and second holding frames 21, 22. 213, 214, 223, 224. In the free state, the side frame 1 is (distance L0 between the bent portions 112 and 222) <(distance L1 between the inner side surfaces 219 and 229). Therefore, as shown in FIG. While the 122 is in contact with the inner side surfaces 219 and 229, a compressive force inward in the stacking direction acts on the inner side surfaces 219 and 229 to fix the side frame 1 to the first and second holding frames 21 and 22.

Next, as shown in FIG. 15, the side cases 23 and 24 are crowned from the outside of the side frame 1. At this time, the engagement piece 235 of the side case 23 is inserted into the openings 213 and 223 of the first and second holding frames 21 and 22, and the claw portion 237 of the engagement piece 235 is inserted into the engagement hole 217, It engages with 227.
Similarly, the engagement pieces 245 of the side case 24 are inserted into the openings 214 and 224, and the claw portions 247 are fitted into the engagement holes 218 and 228 from the inside to be engaged.
Thereafter, the protective case 25 is put on the outside of the side case 24. At this time, the terminal portion 311 of the electrode plate 31 is inserted into the terminal slit 240 of the side case 24, and the terminal portion 311 is fixed to the female terminal 261 between the side case 24 and the protective case 25.

The effect of this example will be described.
The electric heater 2 according to this example is provided with side cases 23 and 24 from outside the side surfaces of the first and second holding frames 21 and 22 constituting the frame-like frame provided on the outer periphery of the heating element 3. On the other hand, engagement using the engagement pieces 235 and 245 and the engagement holes 217, 218, 227 and 228 is performed. At this time, as shown in FIGS. 1 and 2, engagement pieces 235 and 245 are introduced into the first and second holding frames 21 and 22 to engage with each other.

As shown in FIG. 16 described as the prior art, the electric heater configured to cover the frame-like frame inside the side case protrudes outward from the surface of the frame-like frame. .
In contrast to the prior art, as shown in FIGS. 1 and 2, the electric heater 2 according to the present example includes first engagement pieces 235 and 245 provided on the side cases 23 and 24 that constitute a frame-shaped frame. The second holding frames 21 and 22 are introduced into the inside and engaged with the first and second holding frames 21 and 22 inside.
Therefore, it is possible to obtain the side case 23 that does not protrude or protrude from the surfaces of the first and second holding frames 21 and 22.
Further, the side case 24 provided with the flange portion 241 protruding from the main body portion 242 can also be configured so that the main body portion 242 does not protrude from the first and second holding frames 21 and 22.
Therefore, it is possible to obtain the electric heater 2 in which the vicinity of the attachment positions of the side cases 23 and 24 is compact in the thickness direction as compared with the conventional configuration, and thereby the air conditioner to which the electric heater 2 is inserted. The mounting space of the opening such as the duct can be reduced, and the mounting property of the electric heater 2 can be improved.
As mentioned above, according to this example, the electric heater which made the side case attachment part compact in the thickness direction can be provided.

Further, side cases 23 and 24 are provided so as to cover the side surface outside of the heat generating element 3 together with the side frame 1 from outside the side surface of the side frame 1, and engage with the first and second holding frames 21 and 22. Thus, the side cases 23 and 24 can prevent the side frame 1 from falling off.
Further, the engagement pieces 235, 245 of the side cases 23, 24 are inserted into the openings 213, 214, 223, 224 of the first and second holding frames 21, 22, and the engagement pieces 235, 245 can be engaged with the engagement holes 217, 227, 218, and 228, and the engagement between the side cases 23 and 24 and the first and second holding frames 21 and 22 can be further strengthened.

FIG. 3 is a perspective development view of the electric heater according to the first embodiment. 1 is a plan view of an electric heater according to Embodiment 1. FIG. 1 is a schematic diagram of a heating element according to Example 1. FIG. The perspective view of the side part frame concerning Example 1. FIG. Explanatory drawing of a holder and heat generating element concerning Example 1. FIG. The top view of the holder concerning Example 1. FIG. Sectional drawing of the holder concerning Example 1. FIG. The side view of a case concerning Example 1. FIG. The top view of the inner side opposing surface of a case concerning Example 1. FIG. The top view which shows the engagement piece of a case concerning Example 1. FIG. The side view of a case concerning Example 1. FIG. The top view of the inner side opposing surface of a case concerning Example 1. FIG. The top view which shows the engagement piece of a case concerning Example 1. FIG. Explanatory drawing at the time of assembling a side part frame concerning Example 1. FIG. Explanatory drawing at the time of attaching a case concerning Example 1. FIG. An explanatory view of an electric heater concerning the past. Explanatory drawing of the 1st holding | maintenance frame concerning the past. Cross-sectional explanatory drawing of the 1st holding | maintenance frame concerning the former (AA arrow sectional drawing concerning FIG. 17). The principal part explanatory drawing of the electric heater concerning the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Side part frame 2 Electric heater 21 1st holding frame 213, 214, 223, 224 Opening part 217, 218, 227, 228 Engagement hole 22 2nd holding frame 23, 24 Side case 235, 245 Engagement piece 3 Heating element 31 Electrode plate 32 Radiating fin 330 Heating element

Claims (4)

A heat-dissipating fin, a heat-generating element that generates heat when energized, and a heating element configured by laminating electrode plates that apply power to the heat-generating element, and both end surfaces in the stacking direction of the heat-generating element and both side surfaces intersecting the both end surfaces An electric heater in which a medium to be heated passes through the vicinity of the heat dissipating fin from one surface stretched by
A frame-like frame is provided on the outer periphery of the heating element,
Provide side cases on the outside of both sides of the frame-shaped frame,
The inner facing surface of each side case facing the frame-like frame has an engagement piece that protrudes toward the frame-like frame and engages with the frame-like frame,
An electric heater, wherein the engaging pieces of the side cases are respectively introduced into the frame-shaped frame from the side surfaces of the frame-shaped frame and engaged with the frame-shaped frame inside. In Claim 1, the frame-shaped frame includes first and second holding frames provided on both end surfaces of the heating element in the stacking direction, and side frames provided on both side surfaces of the heating element, respectively.
Each side case is provided so as to cover the outer side surface of the heating element together with the side frame from the outer side surface of the side frame, and engages with the first and second holding frames. Electric heater.   In claim 2, in the electric heater, when the length along the passing direction of the medium to be heated is a thickness, the thickness d1 of the side case is compared with the thickness d2 of the first and second holding frames. , D1 ≦ d2. 4. The first and second holding frames according to claim 2, wherein the first and second holding frames are made of a cylindrical member having openings on both side surfaces, and can be engaged with the engaging pieces, and both end surfaces and both sides of the heating element. An engagement hole opening in the surface stretched by the surface,
An electric heater, wherein the engagement piece of the side case is inserted into the opening, and the engagement piece is engaged with the engagement hole from the inner surface of the first and second holding frames. .

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