JP2022147817A - Electric type heater - Google Patents

Abstract

To reduce a portion reducing as much as possible a pressure force by a frame.SOLUTION: A heater part is formed by laminating a plurality of plates holding a plurality of heater elements, a plurality of radiation fins, and a plurality of electrode plates. On both sides of a first direction as a lamination direction, a pair of frames is distributed. On both sides of a second direction orthogonal to the lamination direction, a spring energizing the frame to the heater part side is distributed. A shape of a bottom part of the frame in a state where it is not energized to the spring is set to an arc shape continuously expanded toward a center from an end part of the second direction without interposing a folding point on the heater part side in the first direction. Between each heater element and each electrode plate, and between each heater element and each radiation fin can be pressed with a sufficient force.SELECTED DRAWING: Figure 5

Description

TECHNICAL FIELD The present disclosure relates to an electric heater that heats air, and is suitable for use, for example, in warming the interior of an automobile.

The electric heater has a structure in which frames are arranged on both sides in the first direction, which is the stacking direction of the heater section, and the frames are pressed toward the heater section to crimp the heating element, the heat radiating fins, and the electrode plate in the heater section. It has been known. It is also known to use a spring to press the frame toward the heater section.

Patent Document 1 proposes forming a bending point in the frame in order to increase the pressing force of the frame toward the heater portion.

JP 2009-152172 A

It seems that if the bending point is formed, the pressing force becomes higher than that of the flat frame. However, depending on the position of the bending point, it has been found that as a result of the deformation of the frame with the bending point as the fulcrum, there are areas where the pressing force is reduced. In particular, between the heating element and the electrode plate, and at the joint between the heating element and the heat radiating fins, a sufficient pressing force must be applied to ensure the energization of the heating element and appropriate heat transfer from the heating element. is required. A decrease in the pressing force at such a portion may lead to a decrease in the performance of the electric heater.

In view of the above points, an object of the present disclosure is to minimize the portion where the pressing force of the frame is reduced.

The first aspect of the present disclosure is a plate-shaped heating element that generates heat when energized, a plate that holds a plurality of the heating elements in the plate surface direction of the flat plate, and a plate that is arranged in an air passage to transfer heat from the heating element to the air passage. and an electrode plate for supplying power to the heating element. The heater portion is formed by laminating the plates, the heat dissipation fins, and the electrode plates in a plurality of stages.

A first aspect of the present disclosure is a pair of frames having a U-shaped (U-shaped) cross section on both sides of the first direction, which is the stacking direction of the heater section, with the heater section side being the bottom and the both sides of the bottom being wall sections. , and springs are provided on both sides in a second direction perpendicular to the stacking direction of the heater section to bias the frame toward the heater section.

The first aspect of the present disclosure is to change the shape of the bottom of the frame in a state in which it is not biased by the spring toward the center from the end in the second direction so that the bending point is non-flexible toward the heater portion in the first direction. It has an arc shape that continuously bulges out with the interposition. Here, the circular arc shape does not necessarily have to be circular, and may be any shape including an ellipse and a parabola, and a shape in which bending points are not interposed and continuously bulged.

In this way, since the bending point is not intervening and the arc shape continuously bulges, even when the frame is biased by the spring, it is possible to avoid deformation of the frame with the special bending point as the fulcrum. Therefore, according to the first aspect of the present disclosure, it is possible to connect the heat generating element and the electrode plate and between the heat generating element and the heat radiating fin with a sufficient pressing force.

In the second aspect of the present disclosure, the rigidity of the frame is higher on the center side in the second direction than on the end side in the second direction. Since the frame is pressed by the springs on both sides in the second direction, the pressing force tends to be lower on the center side in the second direction than on the end side. In order to compensate for this, the second aspect of the present disclosure increases the rigidity on the center side.

According to a third aspect of the present disclosure, the shape of the frame is a shape in which a bulging portion that bulges outward is formed on the center side of the wall portion in the second direction. By providing the bulging portion, it is possible to increase the rigidity of the frame on the center side.

According to a fourth aspect of the present disclosure, the frame is shaped such that the height of the wall portion on the center side in the second direction is higher than the height on the end portion side in the second direction. By increasing the height of the wall on the center side, the rigidity of the frame on the center side can be increased.

According to a fifth aspect of the present disclosure, the shape of the frame is a shape in which a hole is formed on the end portion side of the wall portion in the second direction. By forming the holes, it is possible to lower the rigidity of the frame at the ends and relatively increase the rigidity of the center.

According to a sixth aspect of the present disclosure, the shape of the frame is a shape in which a rib is formed on the center side of the bottom portion in the second direction. By forming the ribs, the rigidity of the center side of the frame can be increased.

The seventh aspect of the present disclosure is that the shape of the bottom portion of the frame in a state where it is not biased by the spring is defined by the length of the frame in the second direction being L and the height in the first direction between the end portion and the center of the frame. When h = 0.1 + 2.4 / 1000 × (L-180) + A
The relationship is represented by the following formula. The units in this formula are millimeters. Also, A is a tolerance in manufacturing, plus or minus 0.2 mm. However, when L is 230 mm or less, the tolerance A is plus 0.2 mm, but the lower limit of the height h is 0.02 mm. By setting the extent of swelling to an optimum range, it is possible to connect the heat generating element and the electrode plate and between the heat generating element and the heat radiating fins with an appropriate pressing force.

According to an eighth aspect of the present disclosure, one of the springs is integrally formed with the frame. Since one side is joined, the spring needs to be fixed only on the other side, and the number of assembling steps can be reduced.

A ninth aspect of the present disclosure is that the bottom portion of the frame is formed in two layers, and the shape of the bottom portion on the side of the heater portion is shaped so as to extend from the end portion in the second direction toward the center in a state where the spring does not bias the bottom portion. It has a circular arc shape that continuously bulges in one direction toward the heater portion without intervening bending points. Since it has a double bottom, it is also possible to interpose an arc-shaped spacer that continuously bulges without intervening bending points between the frame having a U-shaped cross section and the heater section. .

1 is a front view of an electric heater of the present disclosure; FIG. 2 is an exploded front view of the electric heater of FIG. 1. FIG. 3 is an enlarged front view of a heating element portion of the electric heater of FIG. 1. FIG. FIG. 4 is a front view showing the shape of the bottom of the frame with two bending points when not biased by the spring. FIG. 5 is a front view explaining a deformed state of a frame having three bending points. FIG. 6 is a front view showing the shape of the bottom of the frame, which does not have a bending point, in an unbiased state by the spring. FIG. 7 is a schematic diagram for explaining deformation states of a frame having a bending point and a frame having no bending point. FIG. 8 is a front view showing the first direction height and the second direction length of the frame. FIG. 9 is a diagram showing the relationship between the height h of the frame and the ratio of the area A that receives the pressing force of the heating element. FIG. 10 is a diagram showing the relationship between the height in the first direction and the length in the second direction of the frame. FIG. 11 is a front view showing a modification of the present disclosure; 12 is a front view of the frame shown in FIG. 11. FIG. FIG. 13 is a front view showing another modification of the present disclosure; FIG. 14 is a front view showing still another modification of the present disclosure. FIG. 15 is a front view showing still another modification of the present disclosure. FIG. 16 is a front view showing another arrangement example of heating elements. FIG. 17 is a front view showing still another modification of the present disclosure. FIG. 18 is a front view showing still another modification of the present disclosure.

An example of the present disclosure will be described below with reference to the drawings. FIG. 1 is a front view showing an example of an electric heater 100. FIG. The electric heater 100 is used with automotive air conditioners. Automotive air conditioners use engine cooling water as a heat source for heating. However, immediately after the engine is started, the engine cooling water is not yet warmed, and the heat source for heating is insufficient. In particular, when automobiles are hybridized and the engines are downsized and the operating rate of the engines is lowered, the amount of heat in the engine cooling water becomes insufficient.

The electric heater 100 is used to compensate for such lack of heat source. It is arranged downstream of the air flow of the heater core of the automotive air conditioner and heats the air sent from the blower fan of the automotive air conditioner. FIG. 2 is an exploded front view showing the components of the electric heater 100. As shown in FIG.

Reference numeral 110 denotes a heating element such as a PCT element, which generates heat when energized. The heating element 110 has a rectangular shape with a length of 35 mm, a width of 6.6 mm, and a thickness of 1.2 mm, and is held in a holding portion 121 of a plate 120 made of a resin material such as nylon. The plate 120 has a thickness of about 1 mm, which is set to be approximately the same as the thickness of the heating element 110 and slightly smaller. Therefore, when the heating element 110 is housed in the holding portion 121 of the plate 120, the one surface 111 and the other surface 112 of the heating element 110 are reliably exposed. This is for ensuring electrical connection with the electrode plate 140, which will be described later.

In FIG. 3, one surface 111 of the heating element 110 is joined to the heat radiating fins 130 . The radiation fin 130 is made of an aluminum alloy containing manganese, and consists of a fin portion 131 formed by bending a number of times and a frame portion 132 for housing the fin portion 131 . The fin portion 131 and the frame portion 132 are integrally brazed. The radiating fins 130 are 10 millimeters high and 7 millimeters wide, with the length depending on the capacity required of the electric heater 100 . As will be described later, the length is about 180 to 280 millimeters.

Since the electrode plate 140 made of aluminum alloy is in contact with the other surface 112 of the heating element 110, it is electrically connected to the electrode plate 140 as described above. The electrode plate 140 is also in contact with the radiating fins 130, and in FIG. Also, the electrode plate 140 on the other surface 112 of the heating element 110 is a negative electrode 142 .

In the example of FIG. 1, five layers of radiation fins 130 are stacked, and four layers of plates 120 (heat generating elements 110) are arranged between the radiation fins 130. In the example of FIG. Five layers of electrode plates 140 are arranged, and positive electrodes 141 and negative electrodes 142 are alternately arranged. In this manner, the heat radiation fins 130, the plates 120, and the electrode plates 140 are stacked in multiple stages to form the heater section 150. FIG. In addition, regarding the direction of arrangement, the stacking direction (vertical direction in FIG. 1) is defined as a first direction, and the direction orthogonal to the stacking direction (horizontal direction in FIG. 1) is defined as a second direction.

Further, in the example of FIG. 1, the heating elements 110 are arranged at four locations at equal intervals in the second direction on the top first plate 123 of the plates 120 in the figure. The four heating elements 110 are designated as a first element 114, a second element 115, a third element 116, and a fourth element 117 from the right in the drawing. On the second plate 124 located second from the top, two heating elements 110 are arranged at positions corresponding to the first element 114 and the third element 116 of the first plate 123 . On the third plate 125 , two heating elements 110 are arranged at positions corresponding to the second element 115 and the fourth element 117 . Similarly to the first plate 123, the fourth plate 126 has four heating elements 110 arranged at equal intervals. The heating element 110 is not arranged on the lowermost fifth plate 127 .

Therefore, in the heater section 150 as a whole, three of the first element 114, the second element 115, the third element 116, and the fourth element 117 are arranged in the first direction. The arrangement of the heating elements 110 is balanced in both the first direction and the second direction of the heater section 150 . As a result, the air passing through the electric heater 100 has a uniform temperature, which contributes to the temperature control of the automotive air conditioner. The length of the heater part 150 in the first direction and the length in the second direction are set according to the duct of the automotive air conditioner. In the present disclosure, the width in the second direction is on the order of 200 to 300 millimeters and the width in the first direction is on the order of 50 to 100 millimeters. Here, it is desirable that the first direction and the second direction are constant without individual variations, but tolerances must be allowed during manufacturing. In particular, it is difficult to completely suppress variations in the first direction. Moreover, the thickness of the heater portion 150 is about 8 millimeters. A thinner thickness is preferable for installation in an air conditioner for automobiles, but the thickness is set to about 8 mm in order to strike a balance between the required amount of heat generation and mountability.

The amount of heat generated by the heating element 110 is controlled by changing the number of positive electrodes 141 to be energized. When obtaining the maximum amount of heat generated, all three positive electrodes 141 are energized. At this time, a positive voltage is applied to the heating element 110 arranged on the first plate 123 from the positive electrode 141 of the first positive electrode plate 145 above, and the electrode of the negative electrode 142 is applied through the heat radiation fin 130 below. Grounded to plate 140 . A positive voltage is applied to the heating element 110 arranged on the second plate 124 from the positive electrode 141 of the intermediate second positive electrode plate 146 , and a negative voltage common to the first plate 123 is applied via the heat radiating fins 130 above. Grounded to electrode 142 .

A positive voltage is applied to the heating element 110 arranged on the third plate 125 from the positive electrode 141 of the intermediate second positive electrode plate 146, and is applied to the lower negative electrode 142 via the lower radiation fin 130. Grounded. A positive voltage is applied to the heating element 110 arranged on the fourth plate 126 from the positive electrode 141 of the third positive electrode plate 147 below, and a negative voltage common to the third plate 125 is applied via the heat radiating fins 130 above. Grounded to electrode 142 .

In order to reduce the amount of heat generated by the heater section 150, the number of the electrode plates 140 to be energized should be reduced. When the amount of heat is minimized, only the second positive electrode plate 146 is energized. At this time, the heating elements 110 arranged on the second plate 124 and the third plate 125 generate heat. Even in this state of minimum heat generation, the heating elements 110 are arranged in the heater section 150 in a well-balanced manner in both the first direction and the second direction. Therefore, the air can be uniformly heated when mounted in an automotive air conditioner.

On both sides of the heater section 150 in the first direction, stainless steel frames 160 sandwiching the heater section 150 are arranged. The length of the frame 160 in the second direction is equal to or slightly longer than that of the radiation fins 130 . Further, the frame 160 has a U-shaped cross-section (U-shaped) in which wall portions 162 extend from both sides of a bottom portion 161 (shown in FIGS. 11 to 15). The width of the bottom portion 161 is about 8 mm, which is the same as the thickness of the heater portion 150, and the height of the wall portion 162 is about 10 mm. Also, the thickness of the frame 160 is about 1 mm.

Springs 170 are arranged on both sides of the frame 160 in the second direction. The spring 170 is a stainless steel bar with a diameter of about 4 millimeters. The spring 170 includes a linear portion 171 along the second direction end of the heater portion 150, bent portions 172 formed at both ends of the linear portion in the first direction, and a pressing force for pressing the frame 160 toward the heater portion 150 side. a portion 173; The spring 170 has elasticity due to the bent portion 172 and presses the frame 160 toward the heater portion 150 (first direction) with a force of about 50 to 190 Newtons. Although the pressing forces of the pair of springs 170 are set to be the same on the left and right sides, it is inevitable that the pressing forces on the left and right sides vary due to the manufacturing process. Also, although not shown in FIG. 1, the spring 170 is housed in a case made of polybutylene terephthalate PBT.

Bonding between the electrode plate 140 of the heater section 150 , the radiation fins 130 and the plate 120 and between the heater section 150 and the frame 160 is maintained solely by the pressing force of this spring 170 . In other words, the electrode plate 140, the radiating fins 130, the plate 120, and the frame 160 are mechanically assembled and not fixed by brazing, welding, or the like. However, in the present disclosure, non-adhesion is not a requirement, and it is possible to adhere the radiation fins 130, the plate 120, and the like.

Here, in order to apply a sufficient pressing force to the plurality of heating elements 110 stacked in the first direction, two bent points 164 are formed in the bottom portion 161 of the frame 160 as described in Patent Document 1. It is also conceivable that the end portion 165 of the frame 160 in the second direction is separated from the heater portion 150 . This seems desirable to increase the pressing force of spring 170 . However, if a shape having two bending points 164 is pressed by a spring 170, as shown in FIG. As a result, the center side of the frame 160 in the second direction is lifted, and the pressing force on the center side is insufficient.

In Patent Document 1, two bending points 164 are formed, but as shown in FIG. 5, three bending points 164 may be provided. However, if the number of bending points 164 is set to three or more points, the two lowest bending points 164 contact the frame 160 when the spring is assembled, and the remaining bending points 164 are subject to pressure due to variations in height. Otherwise, the pressure force cannot be transmitted. Therefore, three or more bending points 164 cannot be set, and the heater section 150 in which a plurality of heating elements 110 are arranged cannot be used. In the example where the bending point 164 is one point, the pressing force is concentrated only on the bending point 164, which is also undesirable.

In the present disclosure, as shown in FIG. 6, the shape of the bottom portion 161 of the frame 160 is an arc shape in which the bending point 164 continuously bulges toward the center from the end portion 165 in the second direction. . Here, the circular arc shape does not define a strict circular shape, but also includes an elliptical shape and a parabolic shape. The important point is that the bending point 164 does not exist and the shape continuously bulges from the end portion 165 toward the heater portion 150 side. Therefore, the arc shape includes a bulging shape with a continuously changing curvature, a smooth bulging shape, a shape bulging in the first direction, a shape bulging toward the center in the second direction, and the like.

A variation of the frame 160 with two bending points 164 shown in FIG. 4 and the continuously bulging frame 160 of the present disclosure shown in FIG. 6 is shown in FIG. FIG. 7(a) shows the shape of the bottom portion 161 of the frame 160 with two bending points 164, and (b) shows the shape of the bottom portion 161 of the frame 160 without the bending points 164 of the present disclosure. A solid line k indicates the shape of the bottom portion 161 without the pressing force of the spring 170, and a dashed line l indicates the deformation of the heater portion 150 in which four layers of plates 120 holding the heating element 110 are laminated with an appropriate load. Give an example.

Due to the deformation of the bottom portion 161 , the region o where a sufficient pressing force cannot be applied to the heater portion 150 side differs depending on the presence or absence of the bending point 164 . If the bending point 164 is not present as in the present disclosure (Fig. 7(b)), narrow the region o where the pressing force is insufficient with respect to the shape with the bending point 164 (Fig. 7(b)) be able to.

If the number of plates 120 is increased, the pressing force of springs 170 must be increased. In that case, the deformation of the bottom 161 is greater, as indicated by the dashed line m in FIG. However, even in the example of the dashed line m, if the bending point 164 is not present as in the present disclosure (FIG. 7B), the shape having the bending point 164 (FIG. 7B) is pressed. The region p where the pressure becomes insufficient becomes narrow. In addition, even if the length of the heater part 150 in the first direction is uneven or the pressing force of the pair of left and right springs 170 is different, a shape that does not have the bending point 164 as in the present disclosure (see FIG. 7 ( In the case of b)), the region p where the pressing force is insufficient is narrower than the shape having the bending point 164 (FIG. 7(b)). In this way, the shape ( FIG. 7B ) in which the bending point 164 does not exist as in the present disclosure makes it easier to provide the necessary pressing force to the heater section 150 .

In the present disclosure, the relationship between the length L of the frame 160 in the second direction and the height h in the first direction (shown in FIG. 8) at the upper end where the pressing force of the spring 170 is not applied is investigated. Specifically, when the pressing force of the spring 170 is applied to the frame 160 and the heat generating element 110 is pressed by the heat radiating fins 130 and the electrode plate 140, how much area of the heat generating element 110 actually covers the heat radiating fins 130 and the electrode plate 140? It was checked whether the electrode plate 140 received a pressing force. Note that the height h in the first direction is the distance between the center of the frame 160 and the end portion 165 .

In FIG. 9, the horizontal axis indicates the height h in the first direction, and the vertical axis indicates the ratio of the area A of the heating element 110 that receives the pressing force. The portion receiving this pressing force refers to a portion receiving a pressing force of about 70 kilopascals or more as a pressing force that can ignore elements such as contact resistance. The solid line indicates the ratio of the area A in the second element 115 and the third element 116 arranged on the central side of the heating elements 110, and the dashed line indicates the ratio of the first element arranged on the end side in the second direction. 114 and the ratio of the area A in the fourth element 117. FIG. A solid line a and a broken line w with triangular points indicate an example in which the length L of the frame 160 (heater section 150) in the second direction is 188 mm. The length L in the direction is 229 millimeters, the solid line c and broken line y of the square points show an example in which the length L of the frame 160 in the second direction is 269 millimeters, and the solid line d and broken line x of the diamond are: An example in which the length L of the frame 160 in the second direction is 296 millimeters is shown. Further, the solid line e, which is a comparative example, indicates the frame 160 having two bending points shown in FIG. 116, and a point v indicates the area ratios of the first element 114 and the fourth element 117 arranged on the end side in the second direction.

As shown in the comparative example of FIG. 9, in the shape having two bending points in FIG. No pressing force is applied (solid line e). Even in the first element 114 and the fourth element 117 arranged on the end side in the second direction, the ratio of the area receiving the pressing force is less than 8% (point v). On the other hand, in the case of an arc shape that continuously bulges without having a bending point as in the present disclosure, about 50% of the pressing force is applied to the heating element 110 on average.

Further, from FIG. 9, it can be seen that in the second element 115 and the third element 116 arranged on the central side, if the height h in the first direction is increased, the ratio of the area subjected to the pressing force tends to increase. . However, in the first element 114 and the fourth element 117 arranged on the end side in the second direction, on the contrary, when the height h in the first direction is increased, the ratio of the area receiving the pressing force tends to decrease. Is recognized. From this, it can be seen that the height h in the first direction has the most well-balanced height when the heater section 150 as a whole is viewed.

In the example in which the length L of the frame 160 in the second direction is 188 mm, the height at which the balance is achieved is determined at the intersection point f between the solid line a and the dashed line w. Similarly, in the example where the length L of the frame 160 in the second direction is 229 mm, the intersection point g between the solid line b and the dashed line x, and in the example where the length L of the frame 160 in the second direction is 269 mm, the solid line c and the dashed line y and the intersection point j of the solid line d and the dashed line z in the example where the length L of the frame 160 in the second direction is 296 millimeters is set to a height that can be balanced.

In FIG. 10, the horizontal axis represents the length L of the frame 160 in the second direction, and the vertical axis represents the height h in the first direction. i, and intersection points j are plotted. From FIG. 10, it can be confirmed that there is a clear correlation between the length L of the frame 160 in the second direction and the height h in the first direction with respect to the above balanced height. If the plotted points in FIG. 10 are approximated by a straight line, the correlation becomes the following linear expression.

h=0.1+2.4/1000×(L-180)+A
In the above formula, the units of the length L of the frame 160 in the second direction and the height h in the first direction of the vertical axis are millimeters. When designing an actual product, considering manufacturing tolerances in the above linear equation, a tolerance A of plus or minus about 0.2 mm is allowed. However, when L is 230 mm or less, the tolerance A is plus 0.2 mm, but the lower limit of the height h is 0.02 mm.

In this example, the length of the heating element 110 in the second direction is constant regardless of the length L of the frame 160 in the second direction, so it is considered that this linear expression holds. That is, if the length L of the frame 160 in the second direction is short, the distance between the adjacent heat generating elements 110 is short. Therefore, even if the height h in the first direction is short, a sufficient pressing force can be applied to the heat generating elements 110. can be done. On the other hand, when the length L of the frame 160 in the second direction increases, the distance between the adjacent heat generating elements 110 also increases accordingly, and the pressing force between the adjacent heat generating elements 110 tends to be lost. Therefore, in order to obtain a sufficient pressing force on the heating element 110, it is required to increase the height h in the first direction.
In the present disclosure, based on the above linear expression, when the length of frame 160 in the second direction is 180 mm, the amount of swelling in the first direction is 0.1 mm, and the length of frame 160 in the second direction is In the case of 230 mm, the swelling amount in the first direction is 0.2 mm. Further, when the length of the frame 160 in the second direction is 290 mm, the amount of swelling in the first direction is 0.35 mm.

As described above, it is desirable to have a continuously bulging shape without the bending point 164 as in the present disclosure in order to increase the ratio of the area A to which the pressing force is applied to the heating element 110 . However, even if the circular arc shape continuously expands, as a result of the spring 170 pressing both ends 165 of the frame 160 in the second direction, as shown in FIG. is concerned. Therefore, in the present disclosure, the rigidity of frame 160 is increased on the center side in the second direction. There are various means for increasing stiffness.

In the example of FIGS. 11 and 12, a bulging portion 166 that bulges outward is formed on the center side of the frame 160 . By forming the bulging portion 166 on the wall portion 162 of the frame 160, the rigidity of the wall portion 162 can be increased on the center side.

In the example of FIG. 13, the height of the wall portion 162 is changed. A high wall portion 167 is formed by making the height of the wall portion 162 on the center side higher than the height on the end portion 165 side. The high wall portion 167 increases the rigidity of the frame 160 on the center side.

In the example of FIG. 14, a hole 168 is formed in the wall portion 162 on the end portion 165 side of the frame 160 . The hole 168 reduces the rigidity of the frame 160 on the end 165 side and relatively increases the rigidity of the frame 160 on the center side.

In the example of FIG. 15, a rib 169 is formed on the bottom portion 161 on the center side of the frame 160 . The rib 169 is formed to bulge from the bottom portion 161 in the direction opposite to the heater portion 150 . By providing the ribs 169, the rigidity of the frame 160 on the center side can be increased.

In the present disclosure, the frame 160 has a shape that continuously expands without the bending point 164 and a shape that increases the rigidity on the center side. The pressing force to 150 can be maintained at a predetermined pressure or more over the entire length in the second direction. In particular, the electric heater 100 of the present disclosure has a structure in which the heating element 110 and the heat radiating fins 130 and the electrode plate 140 are kept bonded only by the pressing force of the spring 170. It is desirable for the performance of the heating element 110 to be able to be maintained over a predetermined pressure over a period of time.

It should be noted that the above example is a desirable correspondence of the present disclosure, but the present disclosure can be modified in various ways. The materials and sizes described above are examples, and can be changed according to the required performance.

The number and arrangement of the heating elements 110 can also be changed variously. 1 and 2, the first plate 123 and the fourth plate 126 are provided with four heating elements 110, namely, a first element 114, a second element 115, a third element 116, and a fourth element 117. was Alternatively, two heating elements 110 may be arranged on all plates 120 as shown in FIG. In the example of FIG. 16, the first element 114 and the fourth element 117 are arranged on the first plate 123 . Similarly, the first element 114 and the third element 116 are arranged on the second plate 124, the second element 115 and the fourth element 117 are arranged on the third plate 125, and the fourth plate 126 has: A first element 114 and a fourth element 117 are arranged. It is the same as the example of FIG. 2 that the heating elements 110 are not arranged on the fifth plate 127 .

In the example of FIG. 16 as well, the positions of the heating elements 110 in the heater section 150 are balanced in both the first direction and the second direction. Also in the example of FIG. 16, the amount of heat generated by the heater section 150 is controlled by controlling the energization of the positive electrode 141 . The most power-saving operation is to energize only the second positive electrode plate 146 . Even during this minimum power operation, the heating elements 110 is balanced in both the first and second directions.

In the above example, the left and right springs 170 have the same shape, but the spring 170 on one side can be configured integrally with the frame 160. In the example of FIG. 17, the left spring 170 is an integrated spring 175 formed integrally with the frame 160 . Attachment of the spring 170 to the frame 160 is performed only with the spring 170 on the right side. Even in this example, the shape of the frame 160 can be a shape that continuously bulges without the bending point 164 present. Also, the shape of the frame 160 may be a shape that enhances the rigidity of the center side.

Further, although in the above example the bottom 161 of the frame 160 was single walled, it could also be double walled. In the example of FIG. 18, the second bottom portion 1611 is interposed between the bottom portion 161 and the heater portion 150 . The shape of the second bottom portion 1611 is such that the bending point 164 does not exist and the shape continuously bulges. Further, even if the second bottom portion 1611 is provided, the shape of the frame 160 can be a shape that increases the rigidity on the center side.

100 Electric heater 110 Heating element 120 Plate 130 Radiation fin 140 Electrode plate 150 Heater section 160 Frame 170 Spring

Claims (9)

a flat heating element that generates heat when energized;
a plate that holds a plurality of the heating elements in the plate surface direction;
a heat radiating fin disposed in the air passage for transferring heat from the heating element to the air passage;
and an electrode plate that supplies power to the heating element,
forming a heater section by stacking a plurality of the plates, the radiation fins, and the electrode plates, respectively;
A pair of frames having a U-shaped (U-shaped) cross-section having a bottom portion on the heater portion side and walls on both sides of the bottom portion are arranged on both sides of the heater portion in the first direction, which is the stacking direction of the heater portion,
springs for urging the frame toward the heater section are provided on both sides in a second direction perpendicular to the stacking direction of the heater section;
The shape of the bottom portion of the frame in a state not biased by the spring is directed from the end portion in the second direction toward the center, and the bending point is continuous to the heater portion side in the first direction without intervening. An electric heater characterized by having an arcuate shape that bulges out. The electric heater according to claim 1, wherein the rigidity of the frame on the center side in the second direction is higher than the rigidity on the end side in the second direction. 3. The electric heater according to claim 2, wherein the frame has a bulging portion that bulges outward on the center side of the wall portion in the second direction. 3. The frame according to claim 2, wherein the height of the wall portion on the center side in the second direction is higher than the height on the end portion side in the second direction. electric heater. The electric heater according to claim 2, wherein the frame has a hole formed in the wall portion on the end portion side in the second direction. The electric heater according to claim 2, wherein the frame has a rib on the center side of the bottom portion in the second direction. The shape of the bottom portion of the frame in a state not biased by the spring is defined by L being the length of the frame in the second direction and the length of the first direction between the end portion and the center of the frame. When the height is h, h = 0.1 + 2.4/1000 x (L-180) + A
The relationship is expressed by the formula, where the units of length L, height h, and A are millimeters, A indicates the tolerance in manufacturing plus or minus 0.2 millimeters, and L is 230 or less 7. The electric heater according to any one of claims 1 to 6, wherein the lower limit of the height h is set to 0.02 mm while A in the case is plus 0.2 mm. The electric heater according to any one of claims 1 to 7, wherein one of the springs is formed integrally with the frame. The bottom portion of the frame is double-formed, and the shape of the bottom portion on the heater portion side thereof is shaped so as to extend from the end portion in the second direction toward the center in the state where the spring does not bias the bottom portion in the first direction. 9. The electric heater according to any one of claims 1 to 8, characterized in that the electric heater has a circular arc shape that continuously bulges without intervening bending points on the heater portion side.

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