Heater unit

Abstract

Provided is a heater unit that can be made lighter in weight due to a thinner heater substrate while maintaining durability. This heater unit is provided with: a housing in which a flow path is formed on the upper surface side; a heater substrate which is disposed on the upper surface side of the housing so as to cover the flow path, and in which a heating element is provided along the flow path on a front surface facing the side opposite to the housing; and at least one frame from among a front surface frame disposed on the front surface of the heater substrate and a rear surface frame disposed on a rear surface of the heater substrate. Said one frame has an outer frame fixing part disposed along the outer peripheral part of the heater substrate, and the outer frame fixing part is fixed to the housing together with the heater substrate by a fastening member.

Description

Heater Unit

[0001] The present invention relates to a heater unit, and more particularly to a heater unit that heats a fluid flowing through a flow path.

[0002] A commonly known conventional heater unit includes a housing in which a flow path is formed and a heater substrate provided with a heating element that heats the fluid flowing through the flow path (see, for example, Patent Documents 1 and 2). In recent years, it has been proposed to use this type of heater unit as a coolant heater for battery temperature management in electric vehicles (EVs).

[0003] Japanese Patent Application Publication No. 11-135241 Special Table No. 2015-524906

[0004] One of the major challenges facing electric vehicles is their driving range. Factors that can extend the driving range of a coolant heater include reducing the vehicle's power consumption by reducing its weight and reducing the coolant heater's power consumption by improving its heating efficiency. While reducing the heater substrate's weight by making it thinner is an option, this can lead to distortion or warping of the heater substrate when a relatively high-pressure fluid flows through the flow path. This can result in problems such as water leakage, cracking of the resistor pattern, and destruction of the insulator. The above problems can also occur in heater units that flow a relatively high-pressure fluid through a flow path, even if they are not coolant heaters for electric vehicles.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a heater unit that can achieve weight reduction by thinning the heater substrate while maintaining durability.

[0006] The present invention is as follows: 1. A heater unit for heating a fluid flowing through a flow path, comprising: a housing having the flow path formed on an upper surface thereof; a heater substrate arranged on the upper surface of the housing so as to cover the flow path, and having a heating element provided along the flow path on a surface facing away from the housing; and at least one of a front frame arranged on the front surface of the heater substrate and a back frame arranged on the back surface of the heater substrate, wherein the one of the frames has an outer frame fixing part arranged along the outer periphery of the heater substrate, and the outer frame fixing part is fixed to the housing together with the heater substrate by a fastening member. 2. The heater unit according to 1. above, wherein the one of the frames has an inner fixing part arranged inside the outer frame fixing part, and the inner fixing part is fixed to the housing together with the heater substrate by a fastening member. 3. The heater unit according to 1. or 2. above, comprising at least the front frame of the front frame and the back frame. 4. The heater unit according to 3. above, wherein the front frame is stacked in multiple stages. 5. The heater unit according to 4. above, wherein a pressing bolt that presses the surface of the heater substrate is screwed into the surface frame on the upper level. 6. The heater unit according to any one of 3. to 5. above, wherein a surface insulating layer is provided on the surface frame in a portion directly below a conductor extending from a power supply terminal of the heating element to the outside of the heater substrate. 7. The heater unit according to 1. above, comprising at least the back frame of the surface frame and the back frame. 8. The heater unit according to 7. above, wherein a back glass layer for preventing warping is provided on the back surface of the heater substrate, and a flat plate is placed on the housing so as to cover the flow path, and the back frame is interposed as a spacer between the heater base and the flat plate so that the back glass layer does not come into contact with the flat plate. 9. The heater unit according to 8. above, further comprising the surface frame. 10. The heater unit according to 7. or 8. above, wherein the back frame has a flow path corresponding portion that is arranged along the flow path inside the outer frame fixing portion.11. The heater unit according to 10. above, wherein the rear frame is formed of a material having a higher thermal conductivity than the heater substrate. 12. The heater unit according to 10. or 11. above, wherein the flow path corresponding portion is provided with a turbulence generating portion for generating turbulence in the fluid flowing through the flow path. 13. The heater unit according to any one of 7. to 12. above, wherein an annular first gasket is interposed between the rear frame and the housing so as to surround the flow path. 14. The heater unit according to 13. above, wherein an annular second gasket is interposed between the rear frame and the heater substrate so as to surround the flow path. 15. The heater unit according to 13. above, wherein an annular O-ring is interposed between the rear frame and the heater substrate so as to surround the flow path. 16. The heater unit according to 13. above, wherein an annular weld is provided between the rear frame and the heater substrate so as to surround the flow path.

[0007] According to the present invention, the front frame and / or the back frame increase the strength of the heater substrate against distortion and warping, so that the heater substrate can be made thinner and lighter while maintaining durability.

[0008] The present invention will be further described in the following detailed description, giving non-limiting examples of exemplary embodiments according to the present invention, with reference to the mentioned drawings, wherein like reference numerals refer to like parts throughout the several views of the drawings.

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[0096] [0 12A and 12B are enlarged cross-sectional views taken along line XIII-XIII in FIG. 12A, where (a) shows a configuration in which a fastening bolt is screwed into an upper-stage front surface frame, and (b) shows a configuration in which the fastening bolt is attached to the upper-stage front surface frame with a nut. A plan view schematically showing a heater unit according to embodiment 5. An enlarged cross-sectional view taken along line XV-XV in FIG. 14A. An explanatory diagram of a front surface frame according to another configuration. An exploded perspective view schematically showing a heater unit according to embodiment 6. A cross-sectional view of a main part of the heater unit. A plan view of a back surface frame constituting the heater unit. An explanatory diagram of a heater substrate constituting the heater unit, where (a) shows a plan view seen from the front surface and (b) shows a plan view seen from the back surface. An exploded perspective view schematically showing a heater unit according to embodiment 7. A cross-sectional view of a main part of the heater unit. A plan view of a back surface frame constituting the heater unit. An explanatory diagram of a heater substrate constituting the heater unit, where (a) shows a plan view seen from the front surface and (b) shows a plan view seen from the back surface. An exploded perspective view schematically showing a heater unit according to a modified example of embodiment 7. 13 is a cross-sectional view of a main part of the heater unit. FIG. 14 is an exploded perspective view schematically showing a heater unit according to a modified example of the seventh embodiment.10A and 10B are cross-sectional views of essential parts of a heater unit; FIG. 10B is an exploded perspective view schematically showing a heater unit according to embodiment 8; FIG. 10C is a cross-sectional view of essential parts of a heater unit; FIG. 10D is a plan view of a rear frame constituting the heater unit; FIG. 10E is a plan view of a housing constituting the heater unit; FIG. 10F is an exploded perspective view schematically showing a heater unit according to embodiment 9; FIG. 10C is a cross-sectional view of essential parts of a heater unit; FIG. 10F is a plan view of a rear frame constituting the heater unit; FIG. 10H is a plan view of a housing constituting the heater unit; FIG. 10I is an explanatory diagram of a rear frame according to a modified example of embodiments 8 and 9; FIG. 10I is a cross-sectional view of essential parts of a heater unit including a modified rear frame, (a) showing a modified example of embodiment 8, and (b) showing a modified example of embodiment 9; FIG. 10I is an explanatory diagram of a rear frame according to another modified example of embodiments 8 and 9, (a) showing a form in which a turbulent flow generating portion having a substantially V-shape in plan view is formed, and (b) showing a form in which a turbulent flow generating portion having a substantially dot-like shape in plan view is formed. FIG. 10I is a cross-sectional view of a heater unit according to yet another modified example of embodiment 9; FIG. 10I is a cross-sectional view of a heater unit according to yet another modified example of embodiment 9; 1A and 1B are plan views schematically showing the circuit pattern of the heat generating element according to the first embodiment, in which (a) shows an overall plan view and (b) shows an enlarged view of a main part.

[0009] The matters set forth herein are for illustrative purposes only and are intended to provide an illustrative description of the embodiments of the present invention, with the aim of providing what is believed to be the most effective and easily understandable explanation of the principles and conceptual features of the present invention. In this regard, it is not intended to show structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken together with the drawings, will make clear to those skilled in the art how some forms of the present invention may be actually embodied.

[0010] <Embodiment 1> As shown in Figures 1 to 3, a heater unit 1A according to this embodiment includes a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on its surface facing away from the housing 3, and a surface frame 5 arranged on the surface of the heater substrate 4.

[0011] The housing 3 is made of a metal such as aluminum. A screw hole 12 into which the threaded portion of the fastening bolt 11 is screwed is formed on the top surface of the housing 3. An inlet 2a and an outlet 2b of the flow path 2 are formed on the side surface of the housing 3. The flow path 2 is open at the top surface of the housing 3 and is formed in a serpentine shape.

[0012] The material of the housing 3 is not particularly limited, and may be formed of, for example, synthetic resin, ceramics, etc. The shape of the housing 3 is not particularly limited, and examples thereof include a planar rectangular shape, a planar polygonal shape other than a quadrangle, a planar circular shape, and a planar elliptical shape. The shape of the flow path 2 is not particularly limited, and examples thereof include one or a combination of two or more of a linear flow path, a curved flow path, a bent flow path, etc. Furthermore, the fluid flowing through the flow path 2 may be, for example, a liquid such as water or oil, a gas, a gel, etc.

[0013] The heater substrate 4 is made of a metal such as steel. The heater substrate 4 covers the upper surface of the housing 3 together with the flow path 2. The heater substrate 4 also has an insertion hole 13 formed therein, through which the threaded portion of the fastening bolt 11 is inserted. The surface of the heater substrate 4 is also provided with a surface insulating layer 8 made of a glass layer or the like that covers the heating element 10. Specifically, the surface insulating layer 8 is formed by printing on the surface of the heater substrate 4.

[0014] The material of the heater substrate 4 is not particularly limited, and can be formed from, for example, metal, ceramic, or a composite material thereof (metal-metal composite, ceramic-ceramic composite, or metal-ceramic composite). A temperature sensor, a fluid detection sensor, a fuse, or the like may be provided on the surface of the heater substrate 4. The shape of the heater substrate 4 is not particularly limited, and examples thereof include a planar rectangular shape, a planar polygonal shape other than a quadrangle, a planar circular shape, and a planar elliptical shape. The material of the surface insulating layer 8 is not particularly limited, and examples thereof include glass, ceramics, and glass-ceramics. Among these, when a metal (such as stainless steel) is used as the material constituting the heater substrate 4, the material of the surface insulating layer 8 is preferably glass, and more preferably crystallized glass or semi-crystallized glass, from the viewpoint of its thermal expansion balance. Specifically, SiO ２ -Al ２ O ３ MO-based glass is preferred, where MO is an oxide of an alkaline earth metal (MgO, CaO, BaO, SrO, etc.). The thickness of the surface insulating layer 8 is not particularly limited (for example, about 30 to 200 μm).

[0015] Here, examples of metals constituting the heater substrate 4 include steel, with stainless steel being particularly preferred. The type of stainless steel is not particularly limited, and ferritic stainless steel and / or austenitic stainless steel are preferred. Among these stainless steels, varieties with particularly excellent heat resistance and / or oxidation resistance are preferred. Examples include SUS430, SUS436, SUS444, and SUS316L. These may be used alone or in combination. Furthermore, aluminum, magnesium, copper, and alloys of these metals may be used as metals constituting the heater substrate 4. These may be used alone or in combination. Among these, aluminum, magnesium, and their alloys (e.g., aluminum alloys, magnesium alloys, and Al-Mg alloys) have low specific gravities, and thus their use can reduce the weight of the heater unit 1A. Furthermore, copper and its alloys have excellent thermal conductivity, and therefore their use can improve the thermal uniformity of the heater unit 1A.

[0016] On the other hand, when the heater substrate 4 is made of ceramics, the material of the heater substrate 4 may be any material that can achieve electrical insulation between the heater substrate 4 and the heating element 10 provided thereon. Preferred substrate materials include, for example, aluminum oxide, aluminum nitride, zirconia, silica, mullite, spinel, cordierite, silicon nitride, etc. These may be used alone or in combination of two or more. Of these, aluminum oxide and aluminum nitride are more preferred. Furthermore, a composite material of metal and ceramic may also be used as the heater substrate 4. Preferred composite materials include, for example, SiC / C, SiC / Al, etc. These may be used alone or in combination of two or more.

[0017] The heating element 10 is composed of a resistance heating wire printed on the surface of the heater substrate 4. The heating element 10 has a power supply line 10a formed along the flow path 2 and a plurality of heating cells 10b electrically connected in parallel to the power supply line 10a (see FIG. 43). The power supply line 10a is a wiring for supplying power to the heating cells 10b from power supply terminals (electrodes) 10c. Specifically, the power supply lines 10a are formed in pairs along the flow path 2. However, the number of power supply lines 10a is not particularly limited. Furthermore, the heating cells 10b are arranged in a row along the flow path 2. Each heating cell 10b is formed in a strip shape. However, the shape, number of rows, etc. of the heating cells 10b are not particularly limited.

[0018] In the heating element 10, the fluid flowing through the flow path 2 is heated by a plurality of heating cells 10b, each of which is connected in parallel to a power supply line 10a and receives a separate power supply. This allows each heating cell 10b to generate heat without being affected by the amount of current flowing through the other heating cells, making it difficult for uneven heat generation due to other heating cells to occur. As a result, the fluid can be heated evenly and efficiently throughout the entire flow path 2 in response to various fluid conditions (e.g., fluid velocity, fluid temperature, etc.).

[0019] The material of the resistance heating wire constituting the heating element 10 is not particularly limited, but a high TCR material (a material with a high temperature coefficient of resistance) can be selected. Furthermore, a conductive material that generates heat according to its resistance value when energized can be used. The conductive material is not limited, but examples include silver, copper, gold, platinum, palladium, rhodium, tungsten, molybdenum, rhenium (Re), and ruthenium (Ru). These materials may be used alone or in combination of two or more. When two or more materials are used in combination, an alloy can be formed. More specifically, silver-palladium alloy, silver-platinum alloy, platinum-rhodium alloy, silver-ruthenium, silver, copper, and gold can be used.

[0020] Each heating cell 10b may have any resistance heating characteristics, but it is preferable that the heating cells 10b can exhibit a self-temperature balancing effect (self-temperature complementing effect) between them. From this perspective, the conductive material constituting the resistance heating wire preferably has a positive temperature coefficient of resistance. Specifically, the temperature coefficient of resistance in the temperature range of -200°C to 1000°C is preferably 100 ppm / °C to 4400 ppm / °C, more preferably 300 ppm / °C to 3700 ppm / °C, and particularly preferably 500 ppm / °C to 3000 ppm / °C. Examples of such materials include silver-based alloys such as silver-palladium alloys.

[0021] When multiple resistance heating wires (i.e., heating cells 10b) made of a conductive material (PTC material) with a positive temperature coefficient of resistance are electrically connected in parallel, these multiple heating cells 10b exhibit a self-temperature balancing effect. For example, if a second heating cell is sandwiched between a first heating cell and a third heating cell, when the temperature of the second heating cell drops, heat is replenished from the first and third heating cells. This replenishment of heat results in an increase in current to the first and third heating cells whose temperatures have dropped, thereby autonomously recovering the temperature drop caused by the lost heat. In other words, the heating cells surrounding the second heating cell act to compensate for the temperature drop of the second heating cell. In this way, a heater equipped with multiple resistance heating wires made of a conductive material with a positive temperature coefficient of resistance is autonomously controlled to generate heat uniformly across the multiple heating cells.

[0022] Typical metal materials used for the resistance heating wire of the heating element 10 include, for example, silver (at 20°C, resistivity ρ=1.62×10 －８ Ωm, temperature coefficient α=4.1×10 －３ / °C), although the temperature coefficient α is large, it is difficult to achieve a high resistance value because the resistivity ρ is small. Therefore, palladium (ρ=10.8×10 －８ Ωm, α=3.7×10 －３ / °C), but although the resistivity ρ increases, the temperature coefficient α decreases. Thus, when a material with high TCR characteristics is selected, the resistivity tends to decrease. Therefore, in order to make the resistive heating wiring have a high TCR and a practical resistance value, the wiring length must be increased. By adopting a meandering shape, the wiring length can be increased and a high resistance value can be achieved.

[0023] The surface frame 5 is made of metal such as stainless steel. The surface frame 5 has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4. The outer frame fixing portion 16 has insertion holes 14 through which the threads of the fastening bolts 11 are inserted. The outer frame fixing portion 16 is fixed to the housing 3 together with the heater substrate 4 by the fastening bolts 11. The material of the surface frame 5 is not particularly limited, and it may be made of, for example, a synthetic resin. The shape of the surface frame 5 is also not particularly limited, and it is usually formed in a shape that overlaps the surface of the heater substrate 4 at a position that avoids the surface insulating layer 8. Furthermore, fastening members such as fastening rivets may be used instead of the fastening bolts 11.

[0024] The heater substrate 4 and the surface frame 5 are placed in this order on the housing 3, and the threaded portions of the fastening bolts 11 are inserted into the insertion holes 13, 14 of the surface frame 5 and the heater substrate 4 and screwed into the screw holes 12 of the housing 3, thereby fixing the heater substrate 4 and the surface frame 5 to the housing 3 (see FIG. 4 ). By combining the surface frame 5 and the heater substrate 4 so that the total thickness t is a predetermined value (e.g., 3 mm), the weight of the heater substrate 4 can be reduced compared to a configuration without the surface frame 5. Specifically, if the stainless steel surface frame 5 (see Figure 1) has a vertical (short) length of 150 mm, a horizontal (long) length of 200 mm, a width (distance between the outer and inner circumference) of 10 mm, and the diameter of the insertion hole 14 is 5 mm, and if the stainless steel heater substrate 4 has a vertical (short) length of 150 mm, a horizontal (long) length of 200 mm, and the diameter of the insertion hole 13 is 5 mm, the weight reduction rate will be as shown in the table below depending on the combination of the thickness of the surface frame 5 and the thickness of the heater substrate 4.

[0025]

[0026] Next, the effects of the heater unit 1A configured as described above will be described. In this embodiment, the heater unit 1A is used for battery temperature management of an electric vehicle (EV). When a fluid (coolant) is circulated between the heater unit 1A and a battery unit (not shown), the fluid that flows in through the inlet 2a and through the flow path 2 of the heater unit 1A is heated by the heating element 10 and then sent to the battery unit through the outlet 2b, thereby maintaining the battery at an optimum operating temperature.

[0027] As described above, the heater unit 1A of the first embodiment includes a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on its surface facing away from the housing 3, and a surface frame 5 arranged on the surface of the heater substrate 4. The surface frame 5 has an outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4, and the outer frame fixing portion 16 is fixed to the housing 3 together with the heater substrate 4 by fastening bolts 11. As a result, even when the thickness of the heater substrate 4 is made thin, for example, less than 3 mm, and a fluid at a high pressure of, for example, 5 to 7 bar is flowed through the flow path 2, the surface frame 5 and the heater substrate 4 are firmly sandwiched between the housing 3 and the heads of the fastening bolts 11, so that the heater substrate 4 is pressed against the housing 3 and the degree of adhesion is increased, thereby increasing the resistance of the heater substrate 4 to distortion and warping.

[0028] Second Embodiment Next, a heater unit 1B according to a second embodiment will be described with reference to FIGS. 5 and 6. Components that are substantially the same as those in the heater unit 1A of the first embodiment are designated by the same reference numerals and will not be described in detail.

[0029] The heater unit 1B of this embodiment comprises a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on the surface facing away from the housing 3, and a surface frame 5 arranged on the surface of the heater substrate 4.

[0030] The surface frame 5 has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4, and an inner fixing portion 17 arranged inside the outer frame fixing portion 16. A plurality of inner fixing portions 17 (three in the figure) are provided as separate parts from the outer frame fixing portion 16. However, only one inner fixing portion 17 may be provided. The inner fixing portion 17 is also arranged between adjacent portions of the heating element 10. Each of the outer frame fixing portion 16 and the inner fixing portion 17 has an insertion hole 14 formed therein through which the threaded portion of the fastening bolt 11 is inserted. Each of the outer frame fixing portion 16 and the inner fixing portion 17 is fixed to the housing 3 together with the heater substrate 4 by the fastening bolt 11.

[0031] As described above, the heater unit 1B of this embodiment 2 has substantially the same effect as the heater unit 1A of the above-mentioned embodiment 1, and the surface frame 5 has an inner fixing portion 17 arranged inside the outer frame fixing portion 16, and the inner fixing portion 17 is fixed to the housing 3 together with the heater substrate 4 by the fastening bolts 11, thereby further increasing the strength of the heater substrate 4 against distortion and warping.

[0032] In the present embodiment, the surface frame 5 has the outer frame fixing portion 16 and the inner fixing portion 17, which are separate components, but the present invention is not limited to this. For example, as shown in Fig. 7, a surface frame 5 having the outer frame fixing portion 16 and the inner fixing portion 17, which are integrated components, may be used. The surface frame 5 shown in Fig. 7 reduces the number of components and improves assembly efficiency. On the other hand, the surface frame 5 shown in Fig. 5 reduces the amount of material used and costs.

[0033] Third Embodiment Next, a heater unit 1C according to a third embodiment will be described with reference to FIGS. 8 to 10. Components that are substantially the same as those in the heater unit 1B of the second embodiment are designated by the same reference numerals and will not be described in detail.

[0034] The heater unit 1C of this embodiment comprises a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on the surface facing away from the housing 3, and surface frames 5A and 5B arranged on the surface of the heater substrate 4.

[0035] The surface frames 5A and 5B are stacked in two stages. The lower stage surface frame 5A is disposed on the surface of the heater substrate 4, and the upper stage surface frame 5B is disposed on the lower stage surface frame 5A. The upper stage surface frame 5B is positioned at a height such that it does not come into contact with the heating element 10 (i.e., the surface insulating layer 8) on the heater substrate 4. The surface frames may be stacked in three or more stages.

[0036] The lower surface frame 5A has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4, and an inner fixing portion 17 arranged inside the outer frame fixing portion 16. On the other hand, the upper surface frame 5B has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4, and an inner fixing portion 17 arranged inside the outer frame fixing portion 16. The inner fixing portion 17 is formed in a frame shape as an integral part with the outer frame fixing portion 16.

[0037] The heater substrate 4 and the surface frames 5A, 5B are placed in this order on the housing 3, and the threaded portions of fastening bolts 11 are inserted into the insertion holes 14, 13 of the surface frames 5A, 5B and the heater substrate 4 and screwed into the screw holes 12 of the housing 3, thereby fixing the heater substrate 4 and the surface frames 5A, 5B to the housing 3 (see FIG. 10 ). By combining the surface frames 5A, 5B and the heater substrate 4 so that the total thickness t is a predetermined value (e.g., 3 mm), the weight of the heater substrate 4 can be reduced compared to a configuration that does not include the surface frames 5A, 5B.

[0038] As described above, the heater unit 1C of this embodiment 3 has substantially the same effect as the heater unit 1B of the above-mentioned embodiment 2, and since the surface frames 5A, 5B are stacked in two stages, the strength of the heater substrate 4 against distortion and warping is further increased.

[0039] Fourth Embodiment Next, a heater unit 1D according to a fourth embodiment will be described with reference to FIGS. 11 to 13. Components that are substantially the same as those in the heater unit 1B of the second embodiment are designated by the same reference numerals and will not be described in detail.

[0040] The heater unit 1D of this embodiment comprises a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on the surface facing away from the housing 3, and surface frames 5A, 5B arranged on the surface of the heater substrate 4.

[0041] The surface frames 5A and 5B are stacked in two stages. The lower stage surface frame 5A is disposed on the surface of the heater substrate 4, and the upper stage surface frame 5B is disposed on the lower stage surface frame 5A. The upper stage surface frame 5B is positioned at a height such that it does not come into contact with the heating element 10 (i.e., the surface insulating layer 8) on the heater substrate 4. The surface frames may be stacked in three or more stages.

[0042] The lower surface frame 5A has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4, and an inner fixing portion 17 arranged inside the outer frame fixing portion 16. On the other hand, the upper surface frame 5B has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4, and an inner fixing portion 17 arranged inside the outer frame fixing portion 16. The inner fixing portion 17 is formed in a frame shape as an integral part with the outer frame fixing portion 16. Furthermore, the inner fixing portion 17 has a screw hole 22 into which a pressure bolt 21 screws.

[0043] The heater substrate 4 and the surface frames 5A and 5B are placed in this order on the housing 3, and the threaded portions of fastening bolts 11 are inserted through the insertion holes 14 and 13 of the surface frames 5A and 5B and the heater substrate 4 and screwed into the screw holes 12 of the housing 3, thereby securing the heater substrate 4 and the surface frames 5A and 5B to the housing 3 (see FIG. 13 ). By combining the surface frames 5A and 5B and the heater substrate 4 so that the total thickness t is a predetermined value (e.g., 3 mm), the weight of the heater substrate 4 can be reduced compared to a configuration without the surface frames 5A and 5B. Furthermore, by threading a pressing bolt 21 into the threaded hole 22 of the inner fixing portion 17 of the upper surface frame 5B, the tip of the threaded portion of the pressing bolt 21 presses the heater substrate 4 toward the housing 3 (see FIG. 13( a)). Note that the fastening bolts 11 are not shown in FIG. 11 .

[0044] As described above, the heater unit 1D of this embodiment 4 has substantially the same effect as the heater unit 1B of the above-mentioned embodiment 2, and since the surface frames 5A, 5B are stacked in two stages, the strength of the heater substrate 4 against distortion and warping is further increased.

[0045] Furthermore, in this fourth embodiment, a pressing bolt 21 that presses against the surface of the heater substrate 4 is screwed into the upper surface frame 5B. This further increases the degree of adhesion of the heater substrate 4 to the housing 3, and further increases the resistance of the heater substrate 4 to distortion and warping. Note that while FIG. 13( a) illustrates an example in which the pressing bolt 21 is screwed into a screw hole 22 formed in the upper surface frame 5B, this is not limiting. For example, as shown in FIG. 13( b), an insertion hole 22 through which the threaded portion of the pressing bolt 21 passes may be formed in the upper surface frame 5B, and the pressing bolt 21 may be attached to the surface frame 5B by tightening it with a nut (particularly a double nut) 53. This embodiment provides the effect of preventing the pressing bolt 21 from loosening.

[0046] Fifth Embodiment Next, a heater unit 1E according to a fifth embodiment will be described with reference to FIGS. 14 and 15. Components that are substantially the same as those in the heater unit 1A of the first embodiment are designated by the same reference numerals and will not be described in detail.

[0047] The heater unit 1E of this embodiment comprises a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on its surface facing away from the housing 3, and a surface frame 5 arranged on the surface of the heater substrate 4.

[0048] The power supply terminal (electrode) 10c is connected to a terminal portion 25 via a conductor (conductor wire) 24. The conductor 24 is arranged so as to straddle the outer frame fixing portion 16 of the surface frame 5. A surface insulating layer 26 made of a glass layer or the like is provided on the outer frame fixing portion 16 of the surface frame 5 in a portion directly below the conductor 24 extending from the power supply terminal 10c of the heating element 10 outward from the heater substrate 4. The material of the surface insulating layer 26 is not particularly limited, and it may be formed of, for example, the same material as the surface insulating layer 8 described above.

[0049] As described above, the heater unit 1E of this embodiment 5 has substantially the same effect as the heater unit 1A of the above-mentioned embodiment 1, and since a surface insulating layer 26 is provided on the surface frame 5 directly below the conductor 24 extending from the power supply terminal 10c of the heating element 10 to the outside of the heater substrate 4, the insulation of the conductor 24 can be easily ensured.

[0050] In the fifth embodiment, the surface insulating layer 26 is provided on the surface frame 5 directly below the conductor 24, but the present invention is not limited to this. For example, as shown in Fig. 16, the surface frame 5 may be recessed in the portion directly below the conductor 24 to form a recess 27. According to this embodiment, the distance from the conductor 24 can be increased to ensure the insulation of the conductor 24. Furthermore, the fifth embodiment may employ the surface frame 5 of any of the second to fourth embodiments.

[0051] Sixth Embodiment Next, a heater unit 1F according to a sixth embodiment will be described with reference to FIGS. 17 to 20. Components that are substantially the same as those in the heater unit 1A of the first embodiment are designated by the same reference numerals and will not be described in detail.

[0052] The heater unit 1F according to this embodiment includes a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on its surface facing away from the housing 3, and a back frame 6 arranged on the back surface of the heater substrate 4. Note that the housing 3 and fastening bolts 11 are not shown in Fig. 17.

[0053] A screw hole 12 into which the threaded portion of the fastening bolt 11 is screwed is formed on the upper surface of the housing 3. A flat plate 28 is arranged on the housing 3 so as to cover the flow path 2. The flat plate 28 is made of a metal such as stainless steel. An insertion hole 29 into which the threaded portion of the fastening bolt 11 is inserted is formed in the flat plate 28.

[0054] While the material for the flat plate 28 is not particularly limited, from the viewpoint of thermal conductivity, it is preferable that the flat plate 28 be formed from a material with a thermal conductivity greater than that of the material for the heater substrate 4. For example, if the heater substrate 4 is made of stainless steel, which has a low thermal conductivity of 50 W / mK or less, the flat plate 28 is preferably formed from a material with a thermal conductivity of 100 W / mK or more. Specifically, silver, copper, gold, aluminum, tungsten, nickel, etc., or an alloy containing at least one of these metals can be used as the thermally conductive metal. These thermally conductive metals may be used alone or in combination of two or more. Among these, aluminum and alloys containing aluminum are particularly preferred from the viewpoint of lightweight construction. The flat plate 28 can also be formed from a thermally conductive ceramic such as aluminum nitride. Furthermore, the shape of the flat plate 28 is not particularly limited, and examples thereof include a planar rectangular shape, a planar polygonal shape other than a square, a planar circular shape, and a planar elliptical shape.

[0055] The heater substrate 4 has an insertion hole 13 through which the threaded portion of the fastening bolt 11 is inserted. A surface insulating layer 8 made of a glass layer or the like that covers the heating element 10 is provided on the surface of the heater substrate 4 (see FIG. 20( a)). A rear glass layer 9 for preventing warping is provided on the rear surface of the heater substrate 4 (see FIG. 20( b)). Specifically, the rear glass layer 9 is printed on the rear surface of the heater substrate 4. The locations of the rear glass layer 9 and the surface insulating layer 8 are almost the same. In addition, a thermally conductive grease layer or a thermally conductive adhesive layer 50 is filled in the gap between the rear glass layer 9 and the flat plate 28 (see FIG. 18). However, a configuration in which the thermally conductive grease layer or the thermally conductive adhesive layer 50 is not filled may also be adopted.

[0056] The material of the rear glass layer 9 is not particularly limited and may be the same as that of the surface insulating layer 8. The type of thermally conductive grease or adhesive layer 50 is not particularly limited, but a base material such as modified silicone mixed with metal or metal oxide particles (filler) can be used. Particles such as silver, copper, gold, aluminum, tungsten, nickel, and alloys containing at least one of these metals can be used as thermally conductive metals. These thermally conductive metals may be used alone or in combination. Among these, silver, copper, aluminum, and alloys containing at least one of these metals are preferred. Furthermore, particles such as alumina, magnesium oxide, and aluminum nitride can also be used. These may be used alone or in combination.

[0057] The back frame 6 is made of a metal such as stainless steel. The back frame 6 is interposed as a spacer between the heater substrate 4 and the flat plate 28 to prevent the back glass layer 9 from contacting the flat plate 28. The back frame 6 has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4 and an inner fixing portion 17 arranged inside the outer frame fixing portion 16 (see FIG. 19 ). The inner fixing portion 17 is formed in a frame shape as an integral part with the outer frame fixing portion 16. Each of the outer frame fixing portion 16 and the inner fixing portion 17 has an insertion hole 14 through which the threaded portion of a fastening bolt 11 is inserted. Each of the outer frame fixing portion 16 and the inner fixing portion 17 is fixed to the housing 3 together with the heater substrate 4 by the fastening bolt 11. The material of the back frame 6 is not particularly limited, and it can be made of, for example, the same material as the flat plate 28. The shape of the back frame 6 is not particularly limited, and it is usually formed in a shape that overlaps the back surface of the heater substrate 4 at a position that avoids the back glass layer 9. Furthermore, fastening members such as fastening rivets may be used instead of the fastening bolts 11. If the rear frame 6 interposed as a spacer is not required, a pattern in which the rear frame 6 is not inserted can also be considered.

[0058] The flat plate 28, rear frame 6, and heater substrate 4 are placed in this order on the housing 3, and the threaded portions of the fastening bolts 11 are inserted through the insertion holes 13, 14, and 29 of the heater substrate 4, rear frame 6, and flat plate 28 and screwed into the screw holes 12 of the housing 3, thereby fixing the flat plate 28, rear frame 6, and heater substrate 4 to the housing 3 (see FIG. 18 ). By combining the rear frame 6, heater substrate 4, and flat plate 28 so that the total thickness t is a predetermined value (e.g., 3 mm), the weight of the heater substrate 4 can be reduced compared to a configuration without the rear frame 6 and flat plate 28. The thickness of the rear frame 6 is preferably 0.3 mm or more so that the rear glass layer 9 does not come into contact with the flat plate 28. Furthermore, the thickness of the flat plate 28 is preferably 0.3 to 0.5 mm from the viewpoint of weight reduction.

[0059] As described above, the heater unit 1F of the sixth embodiment includes a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on its surface facing away from the housing 3, and a back frame 6 arranged on the back surface of the heater substrate 4. The back frame 6 has an outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4, and the outer frame fixing portion 16 is fixed to the housing 3 together with the heater substrate 4 by fastening bolts 11. As a result, even when the thickness of the heater substrate 4 is made thin, for example, less than 3 mm, and a fluid at a high pressure of 5 to 7 bar is flowed through the flow path 2, the heater substrate 4 and the back frame 6 are firmly sandwiched between the housing 3 and the heads of the fastening bolts 11, and the heater substrate 4 is pressed against the housing 3, thereby increasing the degree of adhesion, and therefore the strength of the heater substrate 4 against distortion and warping is increased.

[0060] In addition, in the sixth embodiment, the rear frame 6 has an inner fixing portion 17 disposed inside the outer frame fixing portion 16, and the inner fixing portion 17 is fixed to the housing 3 together with the heater substrate 4 by the fastening bolts 11. This further increases the strength of the heater substrate 4 against distortion and warpage.

[0061] Furthermore, in the sixth embodiment, a back surface glass layer 9 for preventing warpage is provided on the back surface of the heater substrate 4, a flat plate 28 is disposed on the housing 3 so as to cover the flow path 2, and the back surface frame 6 is interposed as a spacer between the heater base material 4 and the flat plate 28 so as to prevent the back surface glass layer 9 from contacting the flat plate 28. This further increases the strength of the heater substrate 4 against distortion and warpage while preventing the back surface glass layer 9 from contacting the flat plate 28. Furthermore, because the flat plate 28 prevents the back surface glass layer 9 from being exposed to the flow path 2, this can be used in cases where it is undesirable to have the back surface glass layer 6 come into contact with the fluid.

[0062] In the sixth embodiment, the rear frame 6 has the outer frame fixing portion 16 and the inner fixing portion 17 that are integral parts, but the present invention is not limited to this, and for example, a rear frame 6 having the outer frame fixing portion 16 and the inner fixing portion 17 that are separate parts may be used. Furthermore, a rear frame 6 that includes only the outer frame fixing portion 16 may be used.

[0063] Seventh Embodiment Next, a heater unit 1G according to a seventh embodiment will be described with reference to FIGS. 21 to 24. Components that are substantially the same as those in the heater unit 1F of the sixth embodiment will be assigned the same reference numerals and will not be described in detail.

[0064] The heater unit 1G according to this embodiment includes a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 disposed on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on its surface facing away from the housing 3, and a back frame 6 disposed on the back surface of the heater substrate 4. A flat plate 28 is disposed on the housing 3 so as to cover the flow path 2. Note that the housing 3 and fastening bolts 11 are not shown in FIG.

[0065] A surface insulating layer 8 made of a glass layer or the like that covers the heating elements 10 is provided on the surface of the heater substrate 4 (see FIG. 24(a)). A rear glass layer 9 for preventing warping is provided on the rear surface of the heater substrate 4 (see FIG. 24(b)). The locations of the rear glass layer 9 and the surface insulating layer 8 do not coincide with each other.

[0066] The rear frame 6 is made of metal such as stainless steel and is interposed as a spacer between the heater substrate 4 and the flat plate 28 so that the rear glass layer 9 does not come into contact with the flat plate 28. The rear frame 6 has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4, and an inner fixing portion 17 arranged inside the outer frame fixing portion 16 (see FIG. 23 ).

[0067] The rear frame 6 has a flow path corresponding portion 37 that is disposed along the heating element 10 (i.e., the surface insulating layer 8) inside the outer frame fixing portion 16. The flow path corresponding portion 37 is disposed in a position facing the flow path 2 across the flat plate 28. The flow path corresponding portion 37 is provided as an integral part of the outer frame fixing portion 16 and the inner fixing portion 17.

[0068] As described above, the heater unit 1G of this embodiment 7 achieves substantially the same effects as the heater unit 1F of the above-mentioned embodiment 6, and the rear frame 6 has a flow path corresponding portion 37 that is arranged along the heating element 10 inside the outer frame fixing portion 16, so that the gap between the heater substrate 4 and the flat plate 28 directly below the heating element 10 is reduced, making it easier for heat to be transmitted to the fluid flowing through the flow path 2, thereby reducing the loss of heat conduction.

[0069] In particular, by using a back frame 6 made of a material (such as aluminum) with a higher thermal conductivity than the material (such as stainless steel) that constitutes the heater substrate 4, the back frame 6 functions as a heat-equalizing layer, leveling out the heat fluctuations that correspond to the pattern shape of the heating element 10, thereby further improving the thermal conductivity.

[0070] <Modifications of Embodiments 6 and 7> The heater units 1F and 1G according to the sixth and seventh embodiments do not include the front frame 5, but are not limited to this and may include, for example, the front frame 5, 5A, or 5B of any of the first to fourth embodiments. For example, as shown in Figures 25 and 26, the front frame 5 of the first embodiment may be combined with the back frame 6 of the seventh embodiment, or as shown in Figures 27 and 28, the front frames 5A and 5B of the fourth embodiment may be combined with the back frame 6 of the seventh embodiment.

[0071] Eighth Embodiment Next, a heater unit 1H according to an eighth embodiment will be described with reference to FIGS. 29 to 32. Components that are substantially the same as those in the heater unit 1A of the first embodiment above will be assigned the same reference numerals and will not be described in detail.

[0072] The heater unit 1H according to this embodiment includes a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 arranged on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on its surface facing away from the housing 3, and a back frame 6 arranged on the back surface of the heater substrate 4. Note that the housing 3 and fastening bolts 11 are not shown in Fig. 29.

[0073] The rear frame 6 is formed of a metal such as stainless steel. The rear frame 6 has an annular outer frame fixing portion 16 arranged along the outer periphery of the heater substrate 4 and an inner fixing portion 17 arranged inside the outer frame fixing portion 16 (see FIG. 31 ). The inner fixing portion 17 is formed in a frame shape as an integral part with the outer frame fixing portion 16. Each of the outer frame fixing portion 16 and the inner fixing portion 17 has an insertion hole 14 through which the threaded portion of the fastening bolt 11 is inserted. Each of the outer frame fixing portion 16 and the inner fixing portion 17 is fixed to the housing 3 together with the heater substrate 4 by the fastening bolt 11. The material of the rear frame 6 is not particularly limited, and it can be formed, for example, from the same material as the flat plate 28 described in the sixth embodiment. The shape of the rear frame 6 is not particularly limited. Furthermore, fastening members such as fastening rivets may be used instead of the fastening bolts 11.

[0074] The rear frame 6 and heater substrate 4 are placed in this order on the housing 3, and the threaded portions of fastening bolts 11 are inserted into the insertion holes 13, 14 of the heater substrate 4 and rear frame 6 and screwed into the screw holes 12 of the housing 3, thereby fixing the rear frame 6 and heater substrate 4 to the housing 3 (see FIG. 30 ). By combining the rear frame 6 and heater substrate 4 so that the total thickness t is a predetermined value (e.g., 3 mm), the weight of the heater substrate 4 can be reduced compared to a configuration without the rear frame 6.

[0075] As described above, the heater unit 1H of the eighth embodiment includes a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 disposed on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path on its surface facing away from the housing 3, and a back frame 6 disposed on the back surface of the heater substrate 4. The back frame 6 has an outer frame fixing portion 16 disposed along the outer periphery of the heater substrate 4, and the outer frame fixing portion 16 is fixed to the housing 3 together with the heater substrate 4 by fastening bolts 11. As a result, even when the thickness of the heater substrate 4 is made thin, for example, less than 3 mm, and a fluid at a high pressure of 5 to 7 bar is flowed through the flow path 2, the heater substrate 4 and the back frame 6 are firmly sandwiched between the housing 3 and the heads of the fastening bolts 11, and the heater substrate 4 is pressed against the housing 3, thereby increasing the degree of adhesion, and therefore the strength of the heater substrate 4 against distortion and warping is increased.

[0076] Furthermore, in the eighth embodiment, the rear frame 6 has an inner fixing portion 17 disposed inside the outer frame fixing portion 16, and the inner fixing portion 17 is fixed to the housing 3 together with the heater substrate 4 by the fastening bolts 11. This further increases the strength of the heater substrate 4 against distortion and warpage.

[0077] In the eighth embodiment, the rear frame 6 has the outer frame fixing portion 16 and the inner fixing portion 17 that are integral parts, but the present invention is not limited to this, and for example, a rear frame 6 having the outer frame fixing portion 16 and the inner fixing portion 17 that are separate parts may be used. Furthermore, a rear frame 6 that includes only the outer frame fixing portion 16 may be used.

[0078] Ninth Embodiment Next, a heater unit 1I according to a ninth embodiment will be described with reference to FIGS. 33 to 36. Components that are substantially the same as those in the heater unit 1H of the eighth embodiment above will be assigned the same reference numerals and will not be described in detail.

[0079] The heater unit 1I according to this embodiment includes a housing 3 having a flow path 2 formed on its upper surface, a heater substrate 4 disposed on the upper surface of the housing 3 so as to cover the flow path 2 and having a heating element 10 provided along the flow path 2 on its surface facing away from the housing 3, and a back frame 6 disposed on the back surface of the heater substrate 4. A ring-shaped gasket 31 (first gasket) made of rubber or synthetic resin is disposed on the housing 3 so as to surround the flow path 2. The gasket 31 has an insertion hole 34 formed therein through which the threaded portion of the fastening bolt 11 is inserted. Note that the housing 3 and fastening bolt 11 are not shown in FIG.

[0080] As described above, the heater unit 1I of this embodiment 9 achieves substantially the same effects as the heater unit 1H of the above-mentioned embodiment 8, and since a ring-shaped gasket 31 is interposed between the rear frame 6 and the housing 3 so as to surround the flow path 2, fluid leakage from between the housing 3 and the rear frame 6 is suppressed, improving the sealing performance of the heater unit 1I.

[0081] <Modifications of Embodiments 8 and 9> In the heater units 1H and 1I of Embodiments 8 and 9 described above, the rear frame 6 has the inner fixing portion 17 arranged so as to largely avoid the heating element 10 (i.e., the surface insulating layer 8), but the present invention is not limited to this, and it is also possible to employ a rear frame 6 having a flow path corresponding portion 37 arranged along the heating element 10 inside the outer frame fixing portion 16, as shown in Figures 37 and 38, for example. According to this embodiment, heat is more easily transferred to the fluid flowing through the flow path 2, thereby reducing heat conduction loss.

[0082] In particular, by using a back frame 6 made of a material (such as aluminum) with a higher thermal conductivity than the material (such as stainless steel) that constitutes the heater substrate 4, the back frame 6 functions as a heat-equalizing layer, leveling out the heat fluctuations that correspond to the pattern shape of the heating element 10, thereby further improving the thermal conductivity.

[0083] 39 , for example, a back frame 6 may be employed in which a turbulence generating section 38 for generating turbulence in the fluid flowing through the flow path 2 is formed in the flow path corresponding section 37. According to this embodiment, the turbulence generating section 38 generates turbulence in the fluid, thereby further improving the thermal conductivity.

[0084] The turbulence generating portions 38 may be, for example, recesses or protrusions, but are preferably exposed portions (through holes) from the viewpoint of processability. The turbulence generating portions 38 may be, for example, (1) a configuration in which a plurality of portions are formed along the flow direction and / or width direction of the flow channel, or (2) a configuration in which a long portion is formed along the flow direction of the flow channel. These (1) and (2) configurations may be used alone or in combination of two or more. In the (1) configuration, the turbulence generating portions 38 may be, for example, V-shaped, U-shaped, W-shaped, L-shaped, or dot-shaped (e.g., circular or polygonal in plan view).

[0085] Furthermore, although the heater units of the above-mentioned embodiments 8 and 9 are in a form that does not include a surface frame 5, this is not limited to this, and the heater units may be in a form that further includes, for example, any of the surface frames 5, 5A, and 5B of the above-mentioned embodiments 1 to 4.

[0086] <Other Modifications of Embodiment 9> In the heater unit 1I of Embodiment 9 described above, the rear frame 6 and the heater substrate 4 are in direct contact with each other, but the present invention is not limited to this. For example, as shown in Fig. 40 , a configuration may be adopted in which an annular gasket 32 ​​(second gasket) is interposed between the rear frame 6 and the heater substrate 4 so as to surround the flow path 2. According to this configuration, the outer frame fixing portion 16 of the rear frame 6 is sandwiched between the pair of gaskets 31, 32, thereby suppressing fluid leakage between the housing 3 and the rear frame 6 and between the heater substrate 4 and the rear frame 6, and further improving the airtightness of the heater unit 1I.

[0087] 41 , for example, a configuration may be adopted in which an annular O-ring 42 is interposed between the rear frame 6 and the heater substrate 4 so as to surround the flow path 2. According to this configuration, the outer frame fixing portion 16 of the rear frame 6 is sandwiched between the gasket 31 and the O-ring 42, thereby suppressing fluid leakage between the housing 3 and the rear frame 6 and between the heater substrate 4 and the rear frame 6, further improving the airtightness of the heater unit 1I. Note that the mounting groove for the O-ring 42 may be formed in the heater substrate 4 or in the rear frame 6.

[0088] 42 , a configuration may be adopted in which an annular welded portion 43 is provided between the rear frame 6 and the heater substrate 4 so as to surround the flow path 2. According to this configuration, the outer frame fixing portion 16 of the rear frame 6 is pressed against the gasket 31 and welded to the outer periphery of the heater substrate 4, thereby suppressing fluid leakage between the housing 3 and the rear frame 6 and between the heater substrate 4 and the rear frame 6, and further improving the airtightness of the heater unit 1I.

[0089] The present invention is not limited to the above-described first to ninth embodiments, and various modifications within the scope of the present invention are possible depending on the purpose and application. That is, a heater unit can be configured by combining the configurations of the above-described first to ninth embodiments. For example, the surface frame 5 with the surface insulating layer 26 of the fifth embodiment (see FIG. 14) may be used as the surface frame 5 of any of the first to fourth embodiments.

[0090] Furthermore, in the above-described sixth and seventh embodiments, a configuration in which a rear surface glass layer 9 is printed on the rear surface of the heater substrate 4 has been exemplified as a countermeasure against warpage of the heater substrate 4. However, in a configuration in which only a surface insulating layer 8 is printed on one side of the heater substrate 4 without a rear surface glass layer 9, countermeasures against warpage of the heater substrate 4 can be taken by straightening the heater substrate 4 by hot pressing or by using a glass material having a thermal expansion coefficient close to that of the heater substrate 4 for the surface insulating layer 8. In this case, the difference between the thermal expansion coefficient A of the surface insulating layer 8 and the thermal expansion coefficient B of the heater substrate 4 is generally within the range of +1% to −35% (i.e., (A−B) / A is 0.01 to −0.35), preferably within the range of 0% to −30% (i.e., (A−B) / A is 0 to −0.3), and more preferably within the range of −3% to −25% (i.e., (A−B) / A is −0.03 to −0.25). The above-described method (correction by hot pressing, etc.) may also be applied to a configuration in which the glass layers 8 and 9 are printed on both sides of the heater substrate 4 .

[0091] Furthermore, in the above-described sixth and seventh embodiments, a configuration in which the rear surface glass layer 9 is not exposed to the flow path 2 by the flat plate 28 has been exemplified, but this is not limited to this, and for example, as shown in FIG. 44, a configuration in which the rear surface glass layer 9 is exposed to the flow path 2 may be applied as any of the above-described first to ninth embodiments.

[0092] Furthermore, the heater units 1A to 1I according to the first to ninth embodiments are not particularly limited in their applications, and can be used, for example, as heater units for battery temperature management and heating of vehicles (for example, automobiles, railroad cars, aircraft, ships, etc.) In particular, they can be suitably used as heater units for battery temperature management and heating of electric vehicles such as battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), plug-in hybrid electric vehicles (PHEVs), and hybrid electric vehicles (HEVs).

[0093] Reference Signs 1A to 1I: heater unit 2; flow path 3; housing 4; heater substrate 5, 5A, 5B; surface frame 6; rear frame 8, 26; surface insulating layer 9; rear glass layer 10; heating element 10c; power supply terminal 11; fastening bolts (fastening members) 16, 16A, 16B; outer frame fixing portion 17, 17A, 17B; inner fixing portion 21; pressure bolt 24; conductor 28; flat plate 31; first gasket 32; second gasket 37; flow path corresponding portion 38; turbulence generating portion 42; O-ring 43; welded portion

Claims

1. A heater unit that heats a fluid flowing through a flow path, comprising: a housing with the flow path formed on its upper surface; a heater substrate that is arranged on the upper surface of the housing so as to cover the flow path and has a heating element provided along the flow path on its surface facing away from the housing; and at least one of a front frame that is arranged on the front surface of the heater substrate and a back frame that is arranged on the back surface of the heater substrate, wherein the one of the frames has an outer frame fixing portion that is arranged along the outer periphery of the heater substrate, and the outer frame fixing portion is fixed to the housing together with the heater substrate by a fastening member.

2. A heater unit according to claim 1, wherein the one frame has an inner fixing portion disposed inside the outer frame fixing portion, and the inner fixing portion is fixed to the housing together with the heater substrate by a fastening member.

3. The heater unit according to claim 1, comprising at least the front frame of the front frame and the rear frame.

4. The heater unit according to claim 3, wherein the surface frame is stacked in multiple stages.

5. The heater unit according to claim 4, wherein a pressure bolt for pressing the surface of the heater substrate is screwed into the upper surface frame.

6. A heater unit according to claim 3, wherein a surface insulating layer is provided on said surface frame in a portion directly below a conductor extending from a power supply terminal of said heating element to the outside of said heater substrate.

7. The heater unit according to claim 1, comprising at least the rear frame of the front frame and the rear frame.

8. A heater unit as described in claim 7, wherein a back surface glass layer for preventing warping is provided on the back surface of the heater substrate, a flat plate is placed on the housing so as to cover the flow path, and the back surface frame is interposed as a spacer between the heater base material and the flat plate so that the back surface glass layer does not come into contact with the flat plate.

9. The heater unit according to claim 8, further comprising the surface frame.

10. The heater unit according to claim 7, wherein the rear frame has a flow path corresponding portion disposed along the flow path inside the outer frame fixing portion.

11. The heater unit according to claim 10, wherein the rear frame is formed from a material having a higher thermal conductivity than the heater substrate.

12. A heater unit according to claim 10, wherein the flow path corresponding portion is provided with a turbulence generating portion for generating turbulence in the fluid flowing through the flow path.

13. The heater unit according to claim 7, wherein a first annular gasket is interposed between the rear frame and the housing so as to surround the flow path.

14. The heater unit according to claim 13, wherein a second annular gasket is interposed between the rear frame and the heater substrate so as to surround the flow path.

15. The heater unit according to claim 13, wherein an annular O-ring is interposed between the rear frame and the heater substrate so as to surround the flow path.

16. The heater unit according to claim 13, wherein an annular weld is provided between the rear frame and the heater substrate so as to surround the flow path.

Images