Ceramic heater

Abstract

The invention provides a ceramic heater for heating liquid, which can restrain damage of the heater even in an empty burning state. A ceramic heater (100) for heating a liquid is provided with: a cylindrical ceramic body (10) having a heating resistor (13) and extending in the direction of an axis (O); and fins (20, 21, 22) protruding from the surface of the ceramic body and having a thermal conductivity greater than that of the ceramic body.

Description

Technical Field

[0001] The present invention relates to a ceramic heater for heating liquids used for, for example, 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).

[0004] Then, the heater pattern is energized and heated, causing the ceramic heater to generate heat.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-133762 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] However, if a ceramic heater is used to heat a medium (liquid) such as a coolant, overboiling occurs when the flow rate of the liquid flowing around the ceramic heater decreases or when the liquid is reduced from the container due to leakage, etc., and the heater becomes an air-burning state (heating state in air).

[0010] As a result, the surface of the ceramic heater becomes high temperature. However, if liquid droplets are applied to this high temperature portion, cracks may be generated in the heater due to thermal shock, thereby damaging the heater.

[0011] Therefore, an object of the present invention is to provide a ceramic heater for heating liquids that can suppress damage to the heater even in an empty-fired state.

[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 cylindrical, 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 has a thermal conductivity greater than the thermal conductivity of the ceramic body.

[0014] According to this ceramic heater, a heat sink is provided protruding from the surface of the ceramic body. Therefore, even if the heater is in an air-fired state (heated in air) and the ceramic body forming the surface of the ceramic heater reaches a high temperature, liquid droplets are not directly applied to the high-temperature portion but are applied to the heat sink and cooled. Therefore, it is possible to suppress the occurrence of cracks in the heater due to thermal shock, thereby preventing the heater from being damaged.

[0015] Furthermore, by cooling the ceramic heater (ceramic body) itself with the heat sink, overheating of the heater can also be suppressed.

[0016] In the ceramic heater of the present invention, the heat sink may have a sheet portion and a base portion for fixing the sheet portion, the entire surface of the ceramic body is covered by the sheet portion and the base portion, and the ceramic heater may also have a sealing component capable of maintaining liquid-tightness between the surface of the ceramic body and the heat sink.

[0017] According to this ceramic heater, it is possible to suppress the intrusion of liquid into the gap between the ceramic body and the heat sink, and it is possible to suppress the boiling of the liquid in the gap and the overheating of the heater.

[0018] In the ceramic heater of the present invention, the heat sink may be made of aluminum or an aluminum alloy, and the surface thereof may be anodized.

[0019] According to this ceramic heater, since the thermal conductivity of the heat sink is increased, the heat dissipation effect is large, and the corrosion of the heat sink by liquid such as coolant can be suppressed by the aluminum anodizing treatment.

[0020] In the ceramic heater of the present invention, the entire surface of the ceramic body may be covered with the base, and the sheet may protrude from the base as a member separate from the base.

[0021] According to this ceramic heater, a form can be adopted in which the sheet portion, which is a member separate from the base portion, is fixed to the base portion, and, for example, a damaged sheet portion can be replaced.

[0022] Effects of the Invention

[0023] According to the present invention, a ceramic heater for heating liquids is obtained, which can suppress damage to the heater even in an empty-fired state. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a perspective view showing a ceramic heater according to an embodiment of the present invention.

[0025] Figure 2 This is a front view of the ceramic heater as seen from the front.

[0026] Figure 3 It is along Figure 1Cross-sectional view along line AA.

[0027] Figure 4 It is a perspective view showing the structure of a ceramic body.

[0028] Description of Reference Numerals

[0029] 10. Ceramic body; 13. Heating resistor; 20, 21, 22. Heat sink; 21a, 22a. Sheet; 21b, 22b. Base; 40. Sealing member; 100. Ceramic heater; O. Axis. DETAILED DESCRIPTION

[0030] The following, with the attached Figure 1 The embodiments of the present invention will now be described.

[0031] Figure 1 1 is a perspective view showing a ceramic heater 100 according to an embodiment of the present invention. Figure 2 This is a front view of the ceramic heater 100 as viewed from the front end. Figure 3 It is along Figure 1 The cross-sectional view of line AA, Figure 4 It is a perspective view showing the structure of the ceramic body 10 .

[0032] The ceramic heater 100 according to the embodiment of the present invention can be used, for example, for air conditioning of electric vehicles or heating and heat preservation of batteries. Furthermore, the ceramic heater 100 is used for liquid heating, and heats a heating target through the liquid by heating a liquid such as a coolant.

[0033] like Figure 1 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 protruding from the surface of the ceramic body 10. In this example, the heat sink 20 covers the surface of the ceramic body 10.

[0034] 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.

[0035] A heating resistor 13 ( Figure 3 ).

[0036] In addition, cylinder also includes "cylinder".

[0037] 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 side (rear end side) of the ceramic body 10. Figure 1 Only one is shown).

[0038] Furthermore, an annular ceramic flange 15 for attaching the ceramic heater 100 to an attachment object (such as an electric car) is provided on the ceramic body 10 slightly closer to the front end than the external terminal 17 and fixed thereto by glass or the like.

[0039] 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 .

[0040] like Figure 2 、 Figure 3 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.

[0041] 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 ).

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] Next, refer to Figure 4 The structure of the ceramic body 10 will be described.

[0048] 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 .

[0049] 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).

[0050] 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 .

[0051] The ceramic tube 11 and the ceramic layer 12 can be formed of, for example, aluminum oxide.

[0052] As described above, according to the ceramic heater 100 of the embodiment of the present invention, the heat sink 20 protrudes from 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 (ceramic body 10) 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.

[0053] Furthermore, by cooling the ceramic heater 100 (ceramic body 10 ) itself using the heat sink 20 , overheating of the heater can also be suppressed.

[0054] 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 liquid-tightness between the surface (surface and back) of the ceramic body 10 and the heat sink 20.

[0055] 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.

[0056] 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.

[0057] The heat sink 20 has no particular limitation on its shape as long as it protrudes from the surface of the ceramic body.

[0058] Alternatively, the heat sink 20 may be made of aluminum or an aluminum alloy and its surface may be anodized. This increases the thermal conductivity of the heat sink 20, thereby achieving a greater heat dissipation effect. Furthermore, the anodization can inhibit corrosion of the heat sink 20 by liquids such as coolants.

[0059] 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 cylindrical ceramic body having a heating resistor, the ceramic body extending in an axial direction; and A heat sink protrudes from a surface of the ceramic body and has a thermal conductivity greater than that of the ceramic body.

2. The ceramic heater according to claim 1, characterized in that The heat sink comprises a sheet portion and a base portion for fixing the sheet portion. The entire surface of the ceramic body is covered by the sheet portion and the base portion, The ceramic heater further includes a sealing member capable of maintaining liquid-tightness between the surface of the ceramic body and the heat sink.

3. The ceramic heater according to claim 1 or 2, characterized in that The heat sink is made of aluminum or aluminum alloy, and the surface is anodized.

4. The ceramic heater according to claim 2, characterized in that The entire surface of the ceramic body is covered with the base, and the sheet protrudes from the base as a member separate from the base.

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