Ceramic heater and liquid heating device

Abstract

The present invention provides a ceramic heater and a liquid heating device capable of improving heating efficiency without hindering the flow of a liquid to be heated. A ceramic heater (100) for heating a liquid is provided with a columnar ceramic body (10) having a heating resistor (13) and extending in the direction of an axis (O), and a plurality of fins (20) protruding from the surface of the ceramic body and extending in the direction of the axis and having a thermal conductivity greater than that of the ceramic body, the fins being provided at a distance from each other in the circumferential direction of the ceramic body. And extends in the axial direction.

Description

Technical Field

[0001] The present invention relates to a ceramic heater and a liquid heating device for heating liquids, for example, used for air conditioning of electric vehicles or heating and heat preservation of batteries. Background Art

[0002] Research is underway to develop systems that use ceramic heaters to heat coolant and other media for air conditioning and battery heating in electric vehicles. Battery heating and insulation are particularly important in cold climates, where battery performance deteriorates.

[0003] This ceramic heater has a structure in which a ceramic layer is wound around the outer circumference of a cylindrical or columnar ceramic tube serving as a core material, and a heater pattern is formed on the ceramic layer (see Patent Document 1). The ceramic heater generates heat by applying electricity to the heater pattern.

[0004] Furthermore, there is known a technique in which a heat dissipation fin is attached to the outer surface side of a ceramic heater to improve the hot air generation characteristics of an air heater (see Patent Document 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-133762

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2-94384 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, the heater described in Patent Document 2 is an air heater and does not take into account the flow of liquid around the heater. Therefore, when the air heater is used to heat liquid, it can improve the heating efficiency of the liquid. However, due to the relationship between the flow direction of the liquid around the heater and the extension direction of the heat sink, the flow of the liquid around the heater is hindered.

[0011] Therefore, an object of the present invention is to provide a ceramic heater and a liquid heating device capable of improving heating efficiency without hindering the flow of heated liquid.

[0012] Solutions for solving problems

[0013] In order to solve the above problems, the ceramic heater of the present invention is a ceramic heater for liquid heating, characterized in that the ceramic heater comprises: a ceramic body, which is columnar, the ceramic body has a heating resistor, and the ceramic body extends along the axial direction; and a heat sink, which protrudes from the surface of the ceramic body and extends along the axial direction, the thermal conductivity of the heat sink is greater than the thermal conductivity of the ceramic body, and the heat sink extends along the axial direction.

[0014] According to this ceramic heater, the heat sink extends in the axial direction. Therefore, if the ceramic heater is placed in the interior space of a liquid container so that the liquid flows at an angle of less than 45 degrees relative to the axial direction, the liquid around the ceramic heater flows in the direction in which the heat sink extends (i.e., the axial direction). As a result, the liquid flows smoothly and unimpeded along the heat sink without flow obstruction, thereby improving the heating efficiency of the heated liquid.

[0015] In the ceramic heater of the present invention, a plurality of the heat dissipation fins may be provided separately in a circumferential direction of the ceramic body.

[0016] According to this ceramic heater, since a plurality of fins are provided, the heating efficiency of the heated liquid can be further improved.

[0017] The liquid heating device of the present invention is characterized in that it comprises: a container having an internal space and an inlet and an outlet connected to the internal space; and a ceramic heater as described in technical solution 1, which extends along the axial direction, and the heating resistor is located in the internal space. In the flow path in which the liquid is introduced from the inlet and flows through the internal space to the outlet, the ceramic heater is used to heat the liquid, and the heat sink faces at least a part of the flow path. When the part facing the heat sink in the flow path is taken as the target flow path, the flow direction in the target flow path is along an angle of less than 45 degrees relative to the axial direction.

[0018] According to this liquid heating device, since the flow direction of the liquid in the container in the target flow path is along the extension direction of the heat sink (i.e., the axial direction), the liquid can flow smoothly and without resistance along the heat sink without hindering the flow, thereby improving the heating efficiency of the heated liquid.

[0019] In the liquid heating device of the present invention, the ceramic body may also have a through hole along the axial direction, one end side of the through hole is connected to the inlet, and the other end side of the through hole faces the internal space, and the flow path is defined as passing through the through hole from the inlet, and flowing out from the front end side of the ceramic body to the outer surface side of the ceramic body, then turning back at the wall of the internal space and heading toward the rear end side, flowing along the outer surface of the ceramic body to the discharge port, and the object flow path is defined by at least the portion from the front end of the ceramic body to the discharge port.

[0020] According to this liquid heating device, the present invention can be applied to a method of passing liquid through the through-holes of the ceramic body.

[0021] In the liquid heating device of the present invention, the axis of the open end of the discharge port facing the internal space may intersect with the axial direction, and a notch portion connected in the circumferential direction may be formed in the heat sink at a portion overlapping with the open end in the axial direction.

[0022] When the axis of the discharge port intersects the axial direction, the liquid flowing in the axial direction along the fin needs to change its direction and flow so as to intersect the axial direction.

[0023] Therefore, by providing the notch, the liquid flowing along the heat sink can easily change its direction in a direction intersecting the axial direction, without hindering the flow of the heated liquid, thereby further improving the heating efficiency.

[0024] In the liquid heating device of the present invention, the heat sink may be attached so as to cover the outer surface of the ceramic body and also cover the inner surface of the through hole of the ceramic body.

[0025] By passing the liquid through the through-holes of the ceramic body, overheating of the heater can be suppressed from the inner surface of the through-holes of the ceramic body. Moreover, the liquid can be heated from the inner surface of the through-holes by the heat sink, further improving the heating efficiency of the heated liquid.

[0026] According to the present invention, a ceramic heater and a liquid heating device are obtained that can improve heating efficiency without hindering the flow of heated liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a cross-sectional view along the axial direction of the liquid heating device according to the embodiment of the present invention.

[0028] Figure 2 It is an exploded perspective view showing the structure of the liquid heating device.

[0029] Figure 3It is a perspective view showing a ceramic heater.

[0030] Figure 4 This is a front view of the ceramic heater as seen from the front.

[0031] Figure 5 It is along Figure 3 Cross-sectional view along line AA.

[0032] Figure 6 It is a perspective view showing the structure of a ceramic body.

[0033] Description of Reference Numerals

[0034] 10. Ceramic body; 10h. Through hole; 13. Heating resistor; 20, 21, 22. Heat sink; 21n. Notch; 100. Ceramic heater; 150. Container; 150i. Internal space; 157. Inlet; 159. Outlet; 159e. Open end of outlet; 200. Liquid heating device; O. Axis; W. Liquid; F. Flow path; Fs. Target flow path; DI. Flow direction in the target flow path; n2. Axis center of the open end of the outlet. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described.

[0036] Figure 1 2 is a cross-sectional view of the liquid heating device 200 according to the embodiment of the present invention, taken along the axis O. Figure 2 is an exploded perspective view showing the structure of the liquid heating device 200. Figure 3 is a perspective view showing the ceramic heater 100. Figure 4 This is a front view of the ceramic heater 100 as viewed from the front end. Figure 5 It is along Figure 3 The cross-sectional view of line AA, Figure 6 It is a perspective view showing the structure of the ceramic body 10 .

[0037] In this embodiment, the liquid heating device 200 can be built with the ceramic heater 100 and used for heating and keeping warm the air conditioner or battery of an electric vehicle, etc. In addition, the ceramic heater 100 is used for liquid heating, and heats the heating object through the liquid by heating the liquid such as coolant.

[0038] like Figure 1 、 Figure 2 As shown, the liquid heating device 200 is generally cylindrical in shape and extends in the axial direction L, and includes a container 150 and a ceramic heater 100 .

[0039] The container 150 includes: a main body 151, which is cylindrical and has an internal space 150i for accommodating liquid W (water); a front end cover 153 and a rear end cover 155, which respectively close the axial end openings of the main body 151; and an inlet 157 and an outlet 159 for liquid W.

[0040] In this example, the direction toward the rear end cover 155 in the axial direction L is referred to as the “rear end side”.

[0041] In addition, both ends of the main body 151 in the axial direction L protrude in the radial direction in the form of flanges, and both ends of the main body 151 are connected to the front end cover 153 and the rear end cover 155 by O-rings 161 and 163 ( Figure 2 ) are hermetically sealed.

[0042] The rear end cover 155 is formed in a substantially block shape and has a through hole 155h extending therethrough in the axial direction L. A cylindrical inlet 157 is attached to the rear end side of the rear end cover 155 via an O-ring (not shown) so as to communicate with the through hole 155h. The inlet 157 extends in the axial direction L.

[0043] The rear end of the main body 151 also has a protrusion 151p formed on its upper surface, protruding in a rectangular box-like shape. The protrusion 151p has a through-hole 151h extending perpendicularly to the axial direction L and communicating with the internal space 150i. A cylindrical outlet 159 is attached to the upper surface of the protrusion 151p, communicating with the through-hole 151h via an O-ring (not shown). The outlet 159 extends perpendicularly to the axial direction L.

[0044] The ceramic heater 100 is in a columnar (cylindrical) shape extending in the direction of the axis O. The flange portion 15 (see FIG. 1 ) provided on the rear end side of the ceramic heater 100 is Figure 3 ) is clamped between the main body 151 and the rear end cover 155, so that the ceramic heater 100 is mounted on the container 150 in a cantilevered manner. Figure 5 ) is located in the internal space 150i.

[0045] In addition, a recess 155r is formed on the front end side of the rear end cover 155 to accommodate the rear end side of the ceramic heater 100 and communicate with the through hole 155h. Figure 3 ) are connected to the leads 15 and 16 described later for supplying power from the outside, and the leads 15 and 16 are led out to the outside from the lead hole 155h2 that is connected to the recess 155r and passes through upward.

[0046] The inlet 157 and the outlet 159 are connected to the internal space 150i and are separated in the axial direction L (also in the direction of the axis O). The liquid W introduced from the outside through the inlet 157 passes through the internal space 150i along the flow direction F and is discharged from the outlet 159.

[0047] In addition, a gap is formed between the inner wall of the container 150 and the ceramic heater 100, and the liquid W introduced into the internal space 150i through the inlet 157 flows in the following flow path: after contacting the outer surface of the ceramic heater 100 along the flow direction F and being heated, it reaches the outlet 159.

[0048] In addition, in this example, the ceramic heater 100 has a through hole 10h along the axis O, and the above-mentioned flow path is defined as flowing from the inlet 157 through the through hole 10h, flowing out from the front end of the through hole 10h to the outside of the ceramic heater 100, then turning back at the wall of the internal space 150i and heading toward the rear end side, and flowing along the outer surface of the ceramic heater 100 to the outlet 159.

[0049] Here, in order to introduce liquid W into the through hole 10h, the rear end of the ceramic heater 100 is in contact with the through hole 155h of the rear end cover 155 via the O-ring 165, so that the through hole 10h and the through hole 155h are sealed liquid-tightly, and one end side (rear end side) of the through hole 10h is connected to the inlet 157.

[0050] Furthermore, the other end side (front end side) of the through hole 10 h faces the internal space 150 i , so that the liquid W passing through the through hole 10 h flows into the internal space 150 i .

[0051] In this example, the ceramic heater 100 is housed in the internal space 150i such that the axial direction L of the liquid heating device 200 (main body 151) is parallel to the axis O of the ceramic heater 100. However, if the flow direction F in the target flow path described later is at an angle less than 45 degrees relative to the axis O, the axial direction L may also form an angle with the axis O.

[0052] Next, refer to Figures 3 to 6 The structure of the ceramic heater 100 will be described.

[0053] like Figure 3 As shown, the ceramic heater 100 includes a cylindrical ceramic body 10 extending in the direction of the axis O, and a heat sink 20 attached so as to protrude from the surface of the ceramic body 10 and extend in the direction of the axis O. In this example, the heat sink 20 covers the surface of the ceramic body 10. In this example, a plurality of heat sinks 20 are provided separately in the circumferential direction of the ceramic body 10.

[0054] The heat sink 20 is made of a material having a higher thermal conductivity than that of the ceramic body, and for example, metal such as aluminum can be used.

[0055] A heating resistor 13 ( Figure 5 ).

[0056] In addition, cylinder also includes "cylinder".

[0057] A pair of external terminals 17 (at the rear end) for electrically heating the heating resistor 13 are exposed on the outer surface of one end (rear end) of the ceramic body 10. Figure 3 Only one is shown).

[0058] Moreover, a circular ceramic flange portion 15 for mounting the ceramic heater 100 on an installation object (the container 150 in this example) is provided on the ceramic body 10 at a position slightly closer to the front end than the external terminal 17 and is fixed by glass or the like.

[0059] Furthermore, the heat sink 20 covers the surface of the ceramic body 10 at a position closer to the front end side than the flange portion 15 .

[0060] like Figure 4 、 Figure 5 As shown, in this example, the ceramic body 10 is cylindrical with a through hole 10h at the center. The liquid flowing in the through hole 10h is heated by the ceramic heater 100, and the liquid on the outer periphery of the ceramic heater 100 is also heated by the ceramic heater 100.

[0061] The heat sink 20 includes a first heat sink 21 covering the outer surface of the ceramic body 10 and a second heat sink 22 covering the inner surface of the ceramic body 10 (the surface of the through hole 10 h ).

[0062] Furthermore, the end surface (front end facing surface) of the ceramic body 10 is covered with a waterproof cover 30 made of a material having a higher thermal conductivity than the ceramic body 10 , for example, an aluminum alloy or a copper alloy.

[0063] Here, a plurality of heat dissipating fins 20 (first heat dissipating fins 21 and second heat dissipating fins 22 ) are provided separately in the circumferential direction of the ceramic body 10 and extend in the axis O direction.

[0064] Furthermore, a circumferentially continuous notch 21n is formed in a portion of the first heat sink 21 closer to the flange 15 along the axis O. The diameter of the notch 21n only needs to be smaller than the diameter of the other portions of the first heat sink 21. In this example, the heat sink itself, which extends along the axis O, is formed on the outer surface of the notch 21n. However, the heat sink does not necessarily need to be formed on the outer surface of the notch 21n.

[0065] The function of the notch portion 21n will be described later.

[0066] Here, the first heat sink 21 integrally includes a cylindrical base 21b along the outer surface of the ceramic body 10 and a plurality of pieces 21a protruding outward from the outer surface of the base 21b. The pieces 21a are spaced apart in the circumferential direction of the base 21b.

[0067] Similarly, the second heat sink 22 integrally includes a cylindrical base 22b extending along the inner surface of the ceramic body 10 and a plurality of fins 22a projecting from the inner surface of the base 22b toward the center. The fins 22a are spaced apart in the circumferential direction of the base 22b, and the front ends of the fins 22a facing each other toward the center are spaced apart, with the center being open.

[0068] Alternatively, the heat sink 20 (the first heat sink 21 and the second heat sink 22 ) may not have a base portion, and each heat sink may be directly attached to the surface of the ceramic body 10 .

[0069] In addition, the gap between the first heat sink 21 and the outer surface of the ceramic body 10, the gap between the second heat sink 22 and the inner surface of the ceramic body 10, and the gaps between the first heat sink 21, the second heat sink 22, and the waterproof cover 30 are respectively sealed and fixed by a liquid-tight sealing component 40 (such as epoxy resin) to maintain these gaps liquid-tight.

[0070] The sealing member 40 may be made of a material other than resin such as thermal grease as long as liquid-tightness can be ensured.

[0071] Next, refer to Figure 6 The structure of the ceramic body 10 will be described.

[0072] The ceramic body 10 includes a ceramic tube 11 and a ceramic layer (ceramic sheet) 12 covering substantially the entire outer circumference of the ceramic tube 11 .

[0073] A heating resistor 13 in a meandering pattern and a pair of internal terminals 26 are formed on the inner circumferential surface (the surface facing the ceramic tube 11) or inside the ceramic layer 12. These internal terminals 26 are electrically connected to external terminals 17 at the ends of the outer circumferential surface of the ceramic layer 12 via through-hole conductors (not shown).

[0074] The heating resistor 13 is arranged near the front end of the ceramic body 10 , and the external terminal 17 is arranged on the rear end side of the ceramic body 10 .

[0075] The ceramic tube 11 and the ceramic layer 12 can be formed of, for example, aluminum oxide.

[0076] As described above, according to the ceramic heater 100 of the embodiment of the present invention, the heat sink 20 covers the surface of the ceramic body 10. Therefore, even if the heater is in an air-fired state (heating state in air) and the surface of the ceramic heater 100 reaches a high temperature, liquid droplets are not directly applied to the high-temperature portion but are applied to the heat sink 20 and cooled. Therefore, it is possible to suppress the occurrence of cracks in the heater due to thermal shock, which may cause damage to the heater.

[0077] Furthermore, by cooling the ceramic heater 100 itself using the heat sink 20 , overheating of the heater can also be suppressed.

[0078] In addition, in this example, the entire surface (surface and back) of the ceramic body 10 is covered by the heat sink 20 (sheet portions 21a, 22a and base portions 21b, 22b), and is also provided with a sealing component 40 that can maintain a liquid-tight connection between the surface (surface and back) of the ceramic body 10 and the heat sink 20.

[0079] This can suppress the intrusion of liquid into the gap between the ceramic body 10 and the heat sink 20 , and can suppress the boiling of the liquid in the gap and the overheating of the heater.

[0080] Furthermore, in the ceramic heater 100 according to the embodiment of the present invention, a plurality of heat dissipating fins 20 (first heat dissipating fins 21 and second heat dissipating fins 22 ) are provided separately in the circumferential direction of the ceramic body 10 and extend in the axis O direction.

[0081] And, as Figure 1 As shown, the ceramic heater 100 is disposed in the internal space 150i of the container 150 so that the flow direction DI in the target flow path Fs is at an angle less than 45 degrees relative to the axis O direction.

[0082] Therefore, the flow direction DI of the liquid W around the ceramic heater 100 is along the extension direction of the heat sink 20 (21, 22) (i.e., the direction of the axis O). Therefore, the liquid W flows smoothly and without resistance along the heat sink 20, and will not hinder the flow of the liquid W around the ceramic heater 100, thereby improving the heating efficiency of the heated liquid.

[0083] Here, if Figure 1 As shown, a route in which the liquid W is introduced from the inlet 157 of the container 150 and flows through the internal space 150i to the outlet 159 is referred to as a "flow path F".

[0084] The flow path F is a route with the shortest distance between the axis n1 of the open end of the inlet 157 facing the internal space 150i and the center of gravity of the through hole 10h of the ceramic heater 100 located in the internal space 150i, and a route with the shortest distance from the front end of the through hole 10h through the internal space 150i (the gap between the outer surface of the ceramic heater 100 and the wall surface of the container 150) through the axis n2 of the open end 159e of the outlet 159 facing the internal space 150i.

[0085] The opening ends of the inlet 157 and the outlet 159 are the boundaries between the container 150 and the inlet 157 and the outlet 159 , and are the portions of the inlet 157 and the outlet 159 facing the internal space 150 i .

[0086] The target flow path Fs is a portion of the flow path F that the heat sink 20 (the first heat sink 21 and the second heat sink 22) face.

[0087] The flow direction DI is a route of the target flow path Fs of the flow path F.

[0088] When the flow direction DI in the target flow path Fs of the container 150 forms an angle of 45 degrees or more with respect to the axis O direction of the ceramic heater 100, the flow direction DI is not along the extension direction of the heat sink 20 (21, 22) (i.e., the axis O direction), and therefore, the liquid W does not flow smoothly along the heat sink 20, and the flow is hindered.

[0089] The angle formed by the flow direction DI and the axis O direction is preferably 30 degrees or less.

[0090] In the liquid heating device 200 of this example, the axis n2 of the discharge port 159 intersects the axis O direction, and a notch 21n is formed in a portion of the heat sink 20 (first heat sink 21) that overlaps with the opening end 159e in the axis O direction.

[0091] When the axis n2 of the discharge port 159 intersects the axis O direction, the liquid W flowing in the axis O direction along the first heat sink 21 needs to change its direction and flow so as to intersect the axis O direction.

[0092] Therefore, by providing the notch 21n, the liquid W flowing along the first heat sink 21 can easily change its direction in a direction intersecting the axis O, thereby further improving the heating efficiency of the heated liquid.

[0093] Furthermore, in the liquid heating device 200 of this example, the heat dissipating fins 21 and 22 are attached so as to cover the outer surface of the ceramic body 10 and also cover the inner surface of the through hole 10 h of the ceramic body 10 .

[0094] Thus, by passing the liquid W through the through-hole 10h of the ceramic body 10, overheating of the heater can be suppressed from the inner surface of the through-hole 10h of the ceramic body 10. Furthermore, the heat sink 22 can also be used to heat the liquid W from the inner surface of the through-hole 10h, further improving the heating efficiency of the heated liquid.

[0095] The present invention is not limited to the above-described embodiments, and encompasses various modifications and equivalents within the spirit and scope of the present invention.

[0096] For example, the shapes of the liquid heating device, the ceramic heater, the heat sink, etc. are not limited.

[0097] The heat sink 20 can be manufactured, for example, by drawing an aluminum material, or by press working to cut out a fin portion from a metal plate.

Claims

1. A ceramic heater for heating liquid, characterized in that: The ceramic heater has: a ceramic body having a columnar shape and having a heating resistor, the ceramic body extending in an axial direction; and a heat sink protruding from a surface of the ceramic body, the heat sink having a thermal conductivity greater than that of the ceramic body, The heat sink extends along the axial direction.

2. The ceramic heater according to claim 1, characterized in that A plurality of heat dissipation fins are provided separately in the circumferential direction of the ceramic body.

3. A liquid heating device, characterized in that: have: a container having an interior space and an inlet and an outlet communicating with the interior space; and The ceramic heater according to claim 1 or 2, which extends along the axial direction, and the heating resistor is located in the internal space. In a flow path where liquid is introduced from the inlet and flows through the internal space to the outlet, the liquid is heated by the ceramic heater, and The heat sink faces at least a portion of the flow path, When a portion of the flow path facing the heat sink is defined as a target flow path, a flow direction in the target flow path is at an angle smaller than 45 degrees with respect to the axial direction.

4. The liquid heating device according to claim 3, characterized in that The ceramic body has a through hole along the axis direction, One end of the through hole is connected to the inlet, and the other end of the through hole faces the internal space. The flow path is defined as follows: it flows from the inlet through the through hole, flows out from the front end side of the ceramic body to the outer surface side of the ceramic body, then turns back at the wall surface of the internal space and flows toward the rear end side, and flows along the outer surface of the ceramic body to the outlet. The target flow path is defined by a portion of the flow path extending from at least the front end of the ceramic body to the discharge port.

5. The liquid heating device according to claim 3 or 4, characterized in that: The axis of the opening end of the discharge port facing the internal space intersects with the axial direction. A notch portion connected in the circumferential direction is formed in a portion of the heat sink that overlaps with the open end in the axial direction.

6. The liquid heating device according to claim 4, characterized in that The heat sink is mounted so as to cover the outer surface of the ceramic body and also cover the inner surface of the through hole of the ceramic body.

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