EP2941090A1 - Heater - Google Patents
Heater Download PDFInfo
- Publication number
- EP2941090A1 EP2941090A1 EP13869090.4A EP13869090A EP2941090A1 EP 2941090 A1 EP2941090 A1 EP 2941090A1 EP 13869090 A EP13869090 A EP 13869090A EP 2941090 A1 EP2941090 A1 EP 2941090A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ceramic structure
- heater
- groove portion
- folded portion
- heating resistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000919 ceramic Substances 0.000 claims abstract description 118
- 238000010438 heat treatment Methods 0.000 claims abstract description 79
- 230000002093 peripheral effect Effects 0.000 claims description 7
- 238000009751 slip forming Methods 0.000 claims 1
- 239000007789 gas Substances 0.000 description 22
- 230000000052 comparative effect Effects 0.000 description 13
- 238000009826 distribution Methods 0.000 description 10
- 238000012986 modification Methods 0.000 description 7
- 230000004048 modification Effects 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 239000000843 powder Substances 0.000 description 5
- 230000008033 biological extinction Effects 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 4
- 229910052581 Si3N4 Inorganic materials 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 229910010293 ceramic material Inorganic materials 0.000 description 3
- 238000001746 injection moulding Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 3
- 230000008646 thermal stress Effects 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000005219 brazing Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- -1 e.g. Inorganic materials 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/42—Heating elements having the shape of rods or tubes non-flexible
- H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23Q—IGNITION; EXTINGUISHING-DEVICES
- F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
- F23Q7/001—Glowing plugs for internal-combustion engines
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
- H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
- H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
- H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
- H05B2203/027—Heaters specially adapted for glow plug igniters
Definitions
- the present invention relates to a heater that is used for a hair iron, a water heater, an oxygen sensor, an air-fuel ratio sensor, a glow plug, various types of combustors, a semiconductor manufacturing apparatus, etc.
- the ceramic heater described in PTL 1 includes a ceramic base body, a heating section in the ceramic base body, and a lead section in the ceramic base body, the lead section being connected to the heating section.
- the heating section (heating resistor) includes two linear portions arrayed side by side, and a folded portion connecting those linear portions to each other.
- a portion of the ceramic base body (ceramic structure) which is positioned between the two arrayed linear portions near the folded portion, tends to be heated to high temperature.
- a surface of the ceramic structure exhibits a temperature distribution that a region (hereinafter referred to as a "maximally heating region") facing the above-mentioned portion of the ceramic base body takes the highest temperature, and that the temperature gradually lowers as a distance from the maximally heating region increases with the maximally heating region being a center.
- a heater according to one aspect of the present invention includes a ceramic structure, and a heating resistor embedded in the ceramic structure and including a folded portion, in which the ceramic structure includes, in a surface facing the folded portion, a groove portion that surrounds the folded portion in opposing relation.
- a heater according to another aspect of the present invention includes a ceramic structure, and a heating resistor embedded in the ceramic structure and including a folded portion, in which the ceramic structure includes a recess in a region of a surface facing the folded portion, the region overlapping the folded portion.
- a heater 100 according to one embodiment of the present invention will be described in detail below with reference to the drawings.
- Fig. 1 is a perspective view of the heater 100 according to one embodiment of the present invention.
- Fig. 2(a) is a partial enlarged view representing, in enlarged scale, an area A of the heater 100 illustrated in Fig. 1
- Fig. 2(b) is a sectional view taken along a B-B' cross-section.
- the heater 100 according to one embodiment of the present invention includes a ceramic structure 1, a heating resistor 2, power feeders 3, and lead terminals 7.
- the heating resistor 2 and the power feeders 3 are illustrated by broken lines in a way of seeing through the ceramic structure 1.
- the heater 100 is, for example, used for a hair iron, a water heater, an oxygen sensor, an air-fuel ratio sensor, a glow plug, a semiconductor manufacturing apparatus, and so on.
- the ceramic structure 1 serves as a member for holding the heating resistor 2 and the power feeders 3 therein. Because the heating resistor 2 and the power feeders 3 are disposed inside the ceramic structure 1, environmental resistance of the heating resistor 2 and the power feeders 3 can be improved.
- the ceramic structure 1 is a rod-like member.
- the ceramic structure 1 is made of a ceramic material, e.g., alumina, silicon nitride, aluminum nitride, or silicon carbide.
- a short side of an outer periphery of the ceramic structure 1 has a length of 25 mm, and a long side thereof has a length of 25 mm.
- a length of the ceramic structure 1 in the longitudinal direction is 50 mm.
- the heating resistor 2 is a member that generates heat when a current is supplied to it.
- the heating resistor 2 is embedded in the ceramic structure 1.
- the heating resistor 2 faces a surface (hereinafter referred to as a "principal surface") of the ceramic structure 1, the surface including the long side of the outer periphery of the ceramic structure 1 and the side of the ceramic structure 1 in the longitudinal direction.
- the heating resistor 2 includes two linear portions 22 arrayed side by side, and a folded portion 21 connecting those linear portions 22 to each other and having outer and inner circumferences each of which has a semicircular shape.
- the heating resistor 2 is illustrated by broken lines in a way of seeing through the ceramic structure 1.
- the folded portion 21 of the heating resistor 2 is disposed near a fore end of the ceramic structure 1, and the linear portions 22 extend from respective ends of the folded portion 21 toward the rear end side of the ceramic structure 1.
- the heating resistor 2 is made of a conductive ceramic material, e.g., tungsten carbide.
- the heating resistor 2 has a line width of 0.2 to 1.5 mm and a thickness of 0.3 to 3 mm, for example.
- the curvature radius of the folded portion 21 is, for example, 0.15 to 1 mm at the inner circumference and 0.5 to 2 mm at the outer circumference.
- the heat generated from the heating resistor 2 is conducted through the ceramic structure 1 and is radiated to the outside from surfaces of the ceramic structure 1.
- the power feeders 3 are a pair of wiring members that electrically connects the heating resistor 2 to a power supply (not illustrated) outside the ceramic structure 1 in cooperation with the lead terminals 7.
- the power feeders 3 are mostly embedded in the ceramic structure 1, and are electrically connected at one ends to the heating resistor 2. Stated in another way, respective one ends of the power feeders 3 are electrically connected to different ends of the heating resistor 2.
- respective other ends of the power feeders 3 are led out to the surface of the ceramic structure 1 at the rear end side and are connected to the different lead terminals 7 for connection to the external power supply.
- the power feeders 3 are formed linearly as wired lines that are routed inside the ceramic structure 1.
- the power feeders 3 are each made of a conductive ceramic material, e.g., tungsten carbide, and formed as a wired line having lower resistance than the heating resistor 2.
- Each of the power feeders 3 has a line width of, e.g., 0.2 to 2 mm and a thickness of, e.g., 0.3 to 4 ⁇ m.
- the lead terminals 7 are rod-like conductive members that electrically connect the power feeders 3 to the external power supply.
- the lead terminals 7 are joined respectively to the power feeders 3 that are led out to different surfaces of the ceramic structure 1 at the side opposite to the side where the heating resistor 2 is disposed.
- the lead terminals 7 are made of, e.g., nickel.
- the lead terminals 7 and the power feeders 3 are joined to each other by employing, e.g., a brazing alloy.
- a silver solder is used as the brazing alloy.
- Dimensions of each of the lead terminals 7 are, for example, 0.2 to 2 mm in width, 0.2 to 2 mm in thickness, and 10 mm or more in length.
- the heating resistor 2 includes the two linear portions 22 arrayed side by side, and the folded portion 21 connecting those linear portions 22 to each other.
- a portion of the ceramic structure 1 which is positioned between the two arrayed linear portions 22 near the folded portion 21, tends to be heated to high temperature. Therefore, a surface of the ceramic structure 1 takes high temperature particularly in a region (maximally heating region 10) that faces the above-mentioned portion of the ceramic base body.
- the maximally heating region 10 is denoted by a two-dot-chain line.
- the ceramic structure 1 includes, in the surface of its region at the side closer to the fore end than the maximally heating region 10, a groove portion 4 surrounding the folded portion 21 of the heating resistor 2 in opposing relation.
- the groove portion 4 is in the form of a rectangular frame surrounding the folded portion 21 in opposing relation. Therefore, the surface of a portion of the ceramic structure 1 where the groove portion 4 is formed (i.e., a bottom surface of the groove portion 4) can be positioned closer to the heating resistor 2 than the surface of a region around such a portion. With that arrangement, temperature in the surface of the portion of the ceramic structure 1 where the groove portion 4 is formed is more apt to increase.
- the groove portion 4 in which temperature is more apt to increase is formed near the maximally heating region 10, the temperature difference between the maximally heating region 10 and a region in the vicinity of the former can be reduced. Hence unevenness of temperature distribution in a surface of the heater 100 can be suppressed. As a result, long-term reliability of the heater 100 can be improved.
- the groove portion 4 is formed in a square shape dimensioned, for example, such that a width is 0.15 mm, a depth is 0.1 mm, and one side of an outer periphery is 2 mm.
- a region surrounded by the groove portion 4 is positioned at the side closer to the fore end of the ceramic structure 1 than the maximally heating region 10.
- a part of the groove portion 4, the part being positioned closest to the rear end of the ceramic structure 1 is positioned at the side closer to the fore end of the ceramic structure 1 than the maximally heating region 10.
- the groove portion 4 when looking at a cross-section of the ceramic structure 1 sectioned in a direction perpendicular to the surface of the ceramic structure 1, the groove portion 4 preferably has a curved shape. With that feature, thermal stress generated upon the ceramic structure 1 being heated to the high temperature can be suppressed from being concentrated in the groove portion 4.
- a slope of the groove portion 4 at the inner peripheral side is more moderate than that at the outer peripheral side.
- the groove portion 4 may be formed in a circular ring shape. With that feature, thermal stress generated upon the ceramic structure 1 being heated to the high temperature can be suppressed from being concentrated in the groove portion 4.
- a projection 5 may be formed on the surface of the ceramic structure 1 along the outer periphery of the groove portion 4 in continuous relation. With the presence of the projection 5 surrounding the groove portion 4, when gas is supplied and flows around the heater 100, the gas is even more likely to stay in the groove portion 4.
- the projection 5 is formed at a height of 0.01 mm or more as measured from the region surrounded by the groove portion 4.
- the projection 5 when looking at a cross-section of the ceramic structure 1 sectioned in the direction perpendicular to the surface of the ceramic structure 1, the projection 5 may have a curved shape. With that feature, when gas is supplied and flows around the heater 100, the gas can more easily flow into the inside surrounded by the projection 5. As a result, the gas can be efficiently combusted at the inside surrounded by the projection 5.
- the shape of the projection 5 may be, e.g., circular-arc or semi-elliptic.
- a recess 6 may be formed, instead of the groove portion 4 surrounding the folded portion 21 in opposing relation, in a region of the surface of the ceramic structure 1, the region overlapping the folded portion 21.
- the recess 6 is formed in a region of a surface of the ceramic structure 1, the surface facing the folded portion 21 and the region overlapping the folded portion 21, the surface of a portion of the ceramic structure 1 where the recess 6 is formed (i.e., a bottom surface of the recess 6) can be positioned closer to the heating resistor 2 than the surface of a region around such portion.
- the recess 6 in which temperature is more apt to increase is formed near the maximally heating region 10, the temperature difference between the maximally heating region 10 and a region in the vicinity of the former can be reduced. Hence unevenness of temperature distribution in the surface of the heater 100 can be suppressed. As a result, long-term reliability of the heater 100 can be improved.
- the outer circumference of the folded portion 21 has the curvature radius of 1 mm, the recess 6 is formed in a square shape dimensioned, for example, such that a depth is 0.1 mm and one side of an outer periphery is 2 mm.
- the region where the recess 6 overlaps the folded portion 21 is positioned at the side closer to the fore end of the ceramic structure 1 than the maximally heating region 10.
- a part of the recess 6, the part being positioned closest to the rear end of the ceramic structure 1 is positioned at the side closer to the fore end of the ceramic structure 1 than the maximally heating region 10.
- the recess 6 when looking at a cross-section of the ceramic structure 1 sectioned in the direction perpendicular to the surface of the ceramic structure 1, the recess 6 may have a curved shape. With that feature, concentration of thermal stress generated upon the ceramic structure 1 being heated to the high temperature can be suppressed in the recess 6.
- a recess 61 may be formed in overlapped relation to a region of a surface of the ceramic structure 1 at the side opposite to the surface where the recess 6 is formed, the region facing the folded portion 21 of the heating resistor 2.
- the shape of the ceramic structure 1 is not limited to the above-mentioned square rod, and it may be a round rod. Furthermore, a fore end portion of the ceramic structure 1 may have a hemisphere shape.
- the folded portion 21 of the heating resistor 2 is not always limited to the form folded into a semicircular shape as illustrated in the drawings, and it may be folded into a an acute-angular shape or a polygonal shape, e.g., a rectangular shape.
- the folded portion 21 of the heating resistor 2, which faces the surface of the ceramic structure 1, is not always required to be formed such that the folded portion 21 and the linear portions 22 face the surface of the ceramic structure 1 in parallel as illustrated in the drawings.
- the folded portion 21 may face the surface of the ceramic structure 1 in a state inclined relative to the same.
- conductive pastes each containing conductive ceramic powder, a resin binder, etc. and becoming one of the heating resistor 2 and the power feeders 3 after firing are prepared. Furthermore, a ceramic paste containing insulating ceramic powder, a resin binder, etc. and becoming an insulating base body, which constitutes the ceramic structure 1, after firing is prepared.
- a compact made of the conductive paste, having a predetermined shape, and becoming the heating resistor 2 is formed, for example, by the injection molding method using the conductive paste for the heating resistor 2.
- the metallic mold is filled with the conductive paste for the power feeders 3, and compacts made of the conductive paste, having predetermined shapes, and becoming the power feeders 3 are formed integrally with the above-mentioned compact. This leads to a state where the compacts of the heating resistor 2 and the power feeders 3 connected to the heating resistor 2 are held in the metallic mold.
- the compact of the heater 100 including the groove portion 4 or the recess 6, which has the desired shape and size, in the surface of the ceramic structure 1 can be obtained by a method of raising pressure applied to eject an ejection pin when the compact is released from the metallic mold, or by a method of cutting a principal surface of the compact.
- the heater 100 can be fabricated by firing the obtained compact at about 1700°C.
- the firing is preferably performed in an atmosphere of non-oxidizing gas, e.g., hydrogen gas.
- the heater 100 according to EXAMPLE of the present invention was fabricated as follows.
- the heating resistor 2 was fabricated by injection molding, namely by injecting a conductive paste, which contained 50% by mass of tungsten carbide powder, 35% by mass of silicon nitride powder, and 15% by mass of a resin binder, into a metallic mold.
- the metallic mold was filled with the above-mentioned conductive paste becoming the power feeders 3, whereby the power feeders 3 were formed and connected to the heating resistor 2.
- the heater 100 was formed in which the heating resistor 2 and the power feeders 3 were embedded in the ceramic structure 1, the heating resistor 2 including the folded portion 21 near the fore end of the ceramic structure 1.
- Sample 1 a sample was fabricated in which the recess 6 in a depth of 50 ⁇ m with one side having a length of 2.3 mm was formed in a region of a principal surface (5 mm x 30 mm) of the ceramic structure 1, the region being positioned at the fore end side of the ceramic structure 1 and overlapping the folded portion 21. Furthermore, metallic molds having various shapes were prepared, and heaters 100 (Samples 2 to 4) having principal surfaces different in configuration from that of Sample 1 were fabricated. Those Samples each had dimensions of 5 mm in thickness, 10 mm in width, and 30 mm in length, and they were different only in configuration of the principal surface from Sample 1.
- the groove portion 4 in a depth of 50 ⁇ m with one side having a length of 2.3 mm was formed in the principal surface in such a configuration that an inner wall surface at the inner side is inclined more moderately than an inner wall surface at the outer side.
- the groove portion 4 in a depth of 50 ⁇ m with one side having a length of 2.3 mm was formed in the principal surface, and the projection 5 having a height of 20 ⁇ m was further formed in a state surrounding the groove portion 4.
- each sample was set in a gas heater, and an ignition temperature of the gas heater was examined.
- an endurance test was carried out by repeating a cycle of, after supplying a current for 30 sec at the ignition temperature, raising temperature at the fore end of the ceramic structure up to 1200°C, and then stopping the supply of the current for 60 sec.
- the heaters 100 of Samples 1 to 4 continued the normal operation even after the number of cycles reached 230000 or more.
- a crack occurred in the principal surface of the ceramic structure 1 near the maximally heating region 10 when the number of cycles reached about 60000.
- a temperature distribution in a region from the fore end of the ceramic structure 1 to the maximally heating region 10 was measured by employing a radiation thermometer.
- the temperature distribution in the surface of the ceramic structure 1 was measured under the condition that, after raising the temperature at the fore end of the ceramic structure 1 up to 1200°C, the ceramic structure 1 was left to stand for 5 min in a state keeping application of a voltage.
- the temperature in the maximally heating region of the ceramic structure was 1240°C, and the temperature at the fore end of the ceramic structure was 1200°C.
- the temperature in the maximally heating region 10 was 1250°C, the temperature at the fore end was 1230°C, and the temperature in the recess 6 was 1240°C.
- the temperature in the maximally heating region 10 was 1250°C, the temperature at the fore end was 1230°C, and the temperature in the groove portion 4 was 1240°C.
- the temperature in the maximally heating region 10 was 1250°C
- the temperature at the fore end was 1230°C
- the temperature in the groove portion 4 was 1240°C.
- the temperature in the maximally heating region 10 was 1250°C
- the temperature at the fore end was 1230°C
- the temperature in the groove portion 4 was 1240°C.
- the temperature difference in the principal surface of the ceramic structure was relatively large, i.e., 40°C, in the heater of Comparative Example 1, while the relevant temperature difference was relatively small, i.e., 20°C, in the heaters 100 of Samples 1 to 4.
- unevenness of the temperature distribution in the principal surface of the ceramic structure 1 can be reduced by employing the configuration of the heater 100 of the present invention. Consequently, it was also understood that a possibility of the occurrence of a crack in the principal surface of the ceramic structure 1 can be reduced even with repeated use of the heater 100.
- Samples 2 to 4 and Comparative Example 1 were each set inside a casing for the test, the casing being provided with a gas inlet. While continuously supplying gas to flow into the casing, measurement was performed on a time until the gas was ignited after starting supply of a current to each of the heaters 100 of Samples 2 to 4 and the heater of Comparative Example 1, and a time until extinction after stopping the supply of the current.
- the gas was prepared by evaporating diesel fuel.
- the heaters 100 of Samples 2 and 3 the time until the ignition was within 40 sec.
- the time until the ignition took 60 sec.
- the time until the ignition is shortened by 20 sec and ignitibility is improved in comparison with the heater of Comparative Example 1.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Resistance Heating (AREA)
Abstract
Description
- The present invention relates to a heater that is used for a hair iron, a water heater, an oxygen sensor, an air-fuel ratio sensor, a glow plug, various types of combustors, a semiconductor manufacturing apparatus, etc.
- One example of heaters for use in a hair iron and so on is a ceramic heater described in Japanese Unexamined Patent Application Publication No.
2006-40882 PTL 1 includes a ceramic base body, a heating section in the ceramic base body, and a lead section in the ceramic base body, the lead section being connected to the heating section. - In the ceramic heater (hereinafter simply referred to also as the "heater") described in
PTL 1, the heating section (heating resistor) includes two linear portions arrayed side by side, and a folded portion connecting those linear portions to each other. In the heater having such a shape, particularly, a portion of the ceramic base body (ceramic structure), which is positioned between the two arrayed linear portions near the folded portion, tends to be heated to high temperature. Therefore, a surface of the ceramic structure exhibits a temperature distribution that a region (hereinafter referred to as a "maximally heating region") facing the above-mentioned portion of the ceramic base body takes the highest temperature, and that the temperature gradually lowers as a distance from the maximally heating region increases with the maximally heating region being a center. When an uneven temperature distribution is generated in the surface of the ceramic structure as mentioned above, there is a possibility that a crack may occur in the surface of the ceramic structure with repeated use of the heater. As a result, it has been difficult to improve long-term reliability of the heater. - A heater according to one aspect of the present invention includes a ceramic structure, and a heating resistor embedded in the ceramic structure and including a folded portion, in which the ceramic structure includes, in a surface facing the folded portion, a groove portion that surrounds the folded portion in opposing relation.
- A heater according to another aspect of the present invention includes a ceramic structure, and a heating resistor embedded in the ceramic structure and including a folded portion, in which the ceramic structure includes a recess in a region of a surface facing the folded portion, the region overlapping the folded portion.
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Fig. 1 is a perspective view of a heater according to one embodiment of the present invention. -
Fig. 2(a) is a partial enlarged view representing, in enlarged scale, an area A of the heater illustrated inFig. 1 , andFig. 2(b) is a sectional view taken along a B-B' cross-section. -
Fig. 3 is a partial enlarged view of a heater according to a modification of the present invention. -
Fig. 4 is a sectional view of a heater according to a modification of the present invention. -
Fig. 5 is a sectional view of a heater according to a modification of the present invention. -
Fig. 6(a) is a partial enlarged view of the heater according to a modification of the present invention, andFig. 6(b) is a sectional view taken along a C-C' cross-section. -
Fig. 7 is a sectional view of a heater according to a modification of the present invention. -
Fig. 8 is a sectional view of a heater according to a modification of the present invention. - A
heater 100 according to one embodiment of the present invention will be described in detail below with reference to the drawings. -
Fig. 1 is a perspective view of theheater 100 according to one embodiment of the present invention.Fig. 2(a) is a partial enlarged view representing, in enlarged scale, an area A of theheater 100 illustrated inFig. 1 , andFig. 2(b) is a sectional view taken along a B-B' cross-section. As illustrated inFig. 1 , theheater 100 according to one embodiment of the present invention includes aceramic structure 1, aheating resistor 2,power feeders 3, andlead terminals 7. InFig. 1 , theheating resistor 2 and thepower feeders 3 are illustrated by broken lines in a way of seeing through theceramic structure 1. Theheater 100 is, for example, used for a hair iron, a water heater, an oxygen sensor, an air-fuel ratio sensor, a glow plug, a semiconductor manufacturing apparatus, and so on. - The
ceramic structure 1 serves as a member for holding theheating resistor 2 and thepower feeders 3 therein. Because theheating resistor 2 and thepower feeders 3 are disposed inside theceramic structure 1, environmental resistance of theheating resistor 2 and thepower feeders 3 can be improved. Theceramic structure 1 is a rod-like member. Theceramic structure 1 is made of a ceramic material, e.g., alumina, silicon nitride, aluminum nitride, or silicon carbide. When theceramic structure 1 is in the form of a square rod, for example, a short side of an outer periphery of theceramic structure 1 has a length of 25 mm, and a long side thereof has a length of 25 mm. A length of theceramic structure 1 in the longitudinal direction is 50 mm. - The
heating resistor 2 is a member that generates heat when a current is supplied to it. Theheating resistor 2 is embedded in theceramic structure 1. Theheating resistor 2 faces a surface (hereinafter referred to as a "principal surface") of theceramic structure 1, the surface including the long side of the outer periphery of theceramic structure 1 and the side of theceramic structure 1 in the longitudinal direction. As illustrated inFig. 2 , theheating resistor 2 includes twolinear portions 22 arrayed side by side, and a foldedportion 21 connecting thoselinear portions 22 to each other and having outer and inner circumferences each of which has a semicircular shape. Also inFig. 2 , theheating resistor 2 is illustrated by broken lines in a way of seeing through theceramic structure 1. The foldedportion 21 of theheating resistor 2 is disposed near a fore end of theceramic structure 1, and thelinear portions 22 extend from respective ends of the foldedportion 21 toward the rear end side of theceramic structure 1. Theheating resistor 2 is made of a conductive ceramic material, e.g., tungsten carbide. Theheating resistor 2 has a line width of 0.2 to 1.5 mm and a thickness of 0.3 to 3 mm, for example. The curvature radius of the foldedportion 21 is, for example, 0.15 to 1 mm at the inner circumference and 0.5 to 2 mm at the outer circumference. The heat generated from theheating resistor 2 is conducted through theceramic structure 1 and is radiated to the outside from surfaces of theceramic structure 1. - Returning to
Fig. 1 , thepower feeders 3 are a pair of wiring members that electrically connects theheating resistor 2 to a power supply (not illustrated) outside theceramic structure 1 in cooperation with thelead terminals 7. Thepower feeders 3 are mostly embedded in theceramic structure 1, and are electrically connected at one ends to theheating resistor 2. Stated in another way, respective one ends of thepower feeders 3 are electrically connected to different ends of theheating resistor 2. On the other hand, respective other ends of thepower feeders 3 are led out to the surface of theceramic structure 1 at the rear end side and are connected to thedifferent lead terminals 7 for connection to the external power supply. Thepower feeders 3 are formed linearly as wired lines that are routed inside theceramic structure 1. Thepower feeders 3 are each made of a conductive ceramic material, e.g., tungsten carbide, and formed as a wired line having lower resistance than theheating resistor 2. Each of thepower feeders 3 has a line width of, e.g., 0.2 to 2 mm and a thickness of, e.g., 0.3 to 4 µm. - The
lead terminals 7 are rod-like conductive members that electrically connect thepower feeders 3 to the external power supply. Thelead terminals 7 are joined respectively to thepower feeders 3 that are led out to different surfaces of theceramic structure 1 at the side opposite to the side where theheating resistor 2 is disposed. Thelead terminals 7 are made of, e.g., nickel. Thelead terminals 7 and thepower feeders 3 are joined to each other by employing, e.g., a brazing alloy. For example, a silver solder is used as the brazing alloy. Dimensions of each of thelead terminals 7 are, for example, 0.2 to 2 mm in width, 0.2 to 2 mm in thickness, and 10 mm or more in length. - Returning to
Fig. 2(a) , in theheater 100 of this embodiment, theheating resistor 2 includes the twolinear portions 22 arrayed side by side, and the foldedportion 21 connecting thoselinear portions 22 to each other. In theheater 100 having such a shape, particularly, a portion of theceramic structure 1, which is positioned between the two arrayedlinear portions 22 near the foldedportion 21, tends to be heated to high temperature. Therefore, a surface of theceramic structure 1 takes high temperature particularly in a region (maximally heating region 10) that faces the above-mentioned portion of the ceramic base body. InFig. 2(a) , the maximallyheating region 10 is denoted by a two-dot-chain line. - In consideration of the above point, in the
heater 100 of this embodiment, theceramic structure 1 includes, in the surface of its region at the side closer to the fore end than the maximallyheating region 10, agroove portion 4 surrounding the foldedportion 21 of theheating resistor 2 in opposing relation. In this embodiment, thegroove portion 4 is in the form of a rectangular frame surrounding the foldedportion 21 in opposing relation. Therefore, the surface of a portion of theceramic structure 1 where thegroove portion 4 is formed (i.e., a bottom surface of the groove portion 4) can be positioned closer to theheating resistor 2 than the surface of a region around such a portion. With that arrangement, temperature in the surface of the portion of theceramic structure 1 where thegroove portion 4 is formed is more apt to increase. Thus, since thegroove portion 4 in which temperature is more apt to increase is formed near themaximally heating region 10, the temperature difference between themaximally heating region 10 and a region in the vicinity of the former can be reduced. Hence unevenness of temperature distribution in a surface of theheater 100 can be suppressed. As a result, long-term reliability of theheater 100 can be improved. - When the outer circumference of the folded
portion 21 has the curvature radius of 1 mm, thegroove portion 4 is formed in a square shape dimensioned, for example, such that a width is 0.15 mm, a depth is 0.1 mm, and one side of an outer periphery is 2 mm. - Furthermore, in the
heater 100 of this embodiment, a region surrounded by thegroove portion 4 is positioned at the side closer to the fore end of theceramic structure 1 than themaximally heating region 10. Stated in another way, a part of thegroove portion 4, the part being positioned closest to the rear end of theceramic structure 1, is positioned at the side closer to the fore end of theceramic structure 1 than themaximally heating region 10. With that arrangement, unevenness of the temperature distribution can be further suppressed at the fore end side of theceramic structure 1 where a heating target is disposed. It is to be noted that the position of themaximally heating region 10 can be confirmed by measuring the temperature of the surface of theceramic structure 1 with a radiation thermometer, for example. - Moreover, as illustrated in
Fig. 2(b) , when looking at a cross-section of theceramic structure 1 sectioned in a direction perpendicular to the surface of theceramic structure 1, thegroove portion 4 preferably has a curved shape. With that feature, thermal stress generated upon theceramic structure 1 being heated to the high temperature can be suppressed from being concentrated in thegroove portion 4. - In addition, preferably, a slope of the
groove portion 4 at the inner peripheral side is more moderate than that at the outer peripheral side. With that feature, when gas is supplied and flows around theheater 100, the gas flow coming into thegroove portion 4 from the outer peripheral side is moderated at the inner peripheral side, whereby the gas is made more likely to stay in thegroove portion 4. - The present invention is not limited to the above-described embodiment, and it can be practiced with a variety of modifications, improvements, etc. within the scope not departing from the gist of the present invention. For example, as illustrated in
Fig. 3 , thegroove portion 4 may be formed in a circular ring shape. With that feature, thermal stress generated upon theceramic structure 1 being heated to the high temperature can be suppressed from being concentrated in thegroove portion 4. - Alternatively, as illustrated in a sectional view of
Fig. 4 , aprojection 5 may be formed on the surface of theceramic structure 1 along the outer periphery of thegroove portion 4 in continuous relation. With the presence of theprojection 5 surrounding thegroove portion 4, when gas is supplied and flows around theheater 100, the gas is even more likely to stay in thegroove portion 4. When the depth of thegroove portion 4 is, for example, 0.1 mm as measured from the region surrounded by thegroove portion 4, theprojection 5 is formed at a height of 0.01 mm or more as measured from the region surrounded by thegroove portion 4. - As illustrated in
Fig. 5 , when looking at a cross-section of theceramic structure 1 sectioned in the direction perpendicular to the surface of theceramic structure 1, theprojection 5 may have a curved shape. With that feature, when gas is supplied and flows around theheater 100, the gas can more easily flow into the inside surrounded by theprojection 5. As a result, the gas can be efficiently combusted at the inside surrounded by theprojection 5. The shape of theprojection 5 may be, e.g., circular-arc or semi-elliptic. - As illustrated in
Figs. 6(a) and 6(b) , arecess 6 may be formed, instead of thegroove portion 4 surrounding the foldedportion 21 in opposing relation, in a region of the surface of theceramic structure 1, the region overlapping the foldedportion 21. With the arrangement that therecess 6 is formed in a region of a surface of theceramic structure 1, the surface facing the foldedportion 21 and the region overlapping the foldedportion 21, the surface of a portion of theceramic structure 1 where therecess 6 is formed (i.e., a bottom surface of the recess 6) can be positioned closer to theheating resistor 2 than the surface of a region around such portion. Accordingly, temperature in the surface of the portion of theceramic structure 1 where therecess 6 is formed is more apt to increase. Thus, since therecess 6 in which temperature is more apt to increase is formed near themaximally heating region 10, the temperature difference between themaximally heating region 10 and a region in the vicinity of the former can be reduced. Hence unevenness of temperature distribution in the surface of theheater 100 can be suppressed. As a result, long-term reliability of theheater 100 can be improved. When the outer circumference of the foldedportion 21 has the curvature radius of 1 mm, therecess 6 is formed in a square shape dimensioned, for example, such that a depth is 0.1 mm and one side of an outer periphery is 2 mm. - Furthermore, in the
heater 100 illustrated inFig. 6 , the region where therecess 6 overlaps the foldedportion 21 is positioned at the side closer to the fore end of theceramic structure 1 than themaximally heating region 10. Stated in another way, a part of therecess 6, the part being positioned closest to the rear end of theceramic structure 1, is positioned at the side closer to the fore end of theceramic structure 1 than themaximally heating region 10. With that arrangement, unevenness of the temperature distribution can be further suppressed at the fore end side of theceramic structure 1 where a heating target is disposed. - As illustrated in
Fig. 7 , when looking at a cross-section of theceramic structure 1 sectioned in the direction perpendicular to the surface of theceramic structure 1, therecess 6 may have a curved shape. With that feature, concentration of thermal stress generated upon theceramic structure 1 being heated to the high temperature can be suppressed in therecess 6. - As illustrated in
Fig. 8 , arecess 61 may be formed in overlapped relation to a region of a surface of theceramic structure 1 at the side opposite to the surface where therecess 6 is formed, the region facing the foldedportion 21 of theheating resistor 2. With that feature, even when both the surfaces of theheater 100 are used to heat a heating target, the temperature distribution in the surface of theceramic structure 1 can be made more even. - The shape of the
ceramic structure 1 is not limited to the above-mentioned square rod, and it may be a round rod. Furthermore, a fore end portion of theceramic structure 1 may have a hemisphere shape. - The folded
portion 21 of theheating resistor 2 is not always limited to the form folded into a semicircular shape as illustrated in the drawings, and it may be folded into a an acute-angular shape or a polygonal shape, e.g., a rectangular shape. - The folded
portion 21 of theheating resistor 2, which faces the surface of theceramic structure 1, is not always required to be formed such that the foldedportion 21 and thelinear portions 22 face the surface of theceramic structure 1 in parallel as illustrated in the drawings. The foldedportion 21 may face the surface of theceramic structure 1 in a state inclined relative to the same. - One example of a method for manufacturing the
heater 100 of this embodiment will be described below. First, conductive pastes each containing conductive ceramic powder, a resin binder, etc. and becoming one of theheating resistor 2 and thepower feeders 3 after firing are prepared. Furthermore, a ceramic paste containing insulating ceramic powder, a resin binder, etc. and becoming an insulating base body, which constitutes theceramic structure 1, after firing is prepared. - Then, a compact made of the conductive paste, having a predetermined shape, and becoming the
heating resistor 2 is formed, for example, by the injection molding method using the conductive paste for theheating resistor 2. In a state where the compact becoming theheating resistor 2 is held in a metallic mold, the metallic mold is filled with the conductive paste for thepower feeders 3, and compacts made of the conductive paste, having predetermined shapes, and becoming thepower feeders 3 are formed integrally with the above-mentioned compact. This leads to a state where the compacts of theheating resistor 2 and thepower feeders 3 connected to theheating resistor 2 are held in the metallic mold. - Then, in the state where the compacts of the
heating resistor 2 and thepower feeders 3 are held in the metallic mold, a part of the metallic mold is replaced with another one for molding theceramic structure 1. Thereafter, the ceramic paste for theceramic structure 1 is filled into the metallic mold. - At that time, by employing the metallic mold capable of forming the
groove portion 4 or therecess 6 in a region of the surface of theceramic structure 1, the region facing the foldedportion 21 of theheating resistor 1, a compact of theheater 100 is obtained in which theheating resistor 2 and thepower feeders 3 are covered with the compact of the ceramic paste, and in which thegroove portion 4 surrounding the foldedportion 21 in opposing relation or therecess 6 overlapping the foldedportion 21 is formed in the region of the surface of theceramic structure 1, the region facing the foldedportion 21 of theheating resistor 2. Then, the compact of theheater 100 including thegroove portion 4 or therecess 6, which has the desired shape and size, in the surface of theceramic structure 1 can be obtained by a method of raising pressure applied to eject an ejection pin when the compact is released from the metallic mold, or by a method of cutting a principal surface of the compact. - Then, the
heater 100 can be fabricated by firing the obtained compact at about 1700°C. The firing is preferably performed in an atmosphere of non-oxidizing gas, e.g., hydrogen gas. - The
heater 100 according to EXAMPLE of the present invention was fabricated as follows. First, theheating resistor 2 was fabricated by injection molding, namely by injecting a conductive paste, which contained 50% by mass of tungsten carbide powder, 35% by mass of silicon nitride powder, and 15% by mass of a resin binder, into a metallic mold. In a state where the moldedheating resistor 2 was held in the metallic mold, the metallic mold was filled with the above-mentioned conductive paste becoming thepower feeders 3, whereby thepower feeders 3 were formed and connected to theheating resistor 2. - Next, in a state where the
heating resistor 2 and thepower feeders 3 were held in a metallic mold, injection molding was performed by injecting, into the metallic mold, a ceramic paste containing 85% by mass of silicon nitride powder, and 10% by mass of biytterbium trioxide, and 5% by mass of tungsten carbide, the latter two serving as sintering aids. As a result, theheater 100 was formed in which theheating resistor 2 and thepower feeders 3 were embedded in theceramic structure 1, theheating resistor 2 including the foldedportion 21 near the fore end of theceramic structure 1. - As
Sample 1, a sample was fabricated in which therecess 6 in a depth of 50 µm with one side having a length of 2.3 mm was formed in a region of a principal surface (5 mm x 30 mm) of theceramic structure 1, the region being positioned at the fore end side of theceramic structure 1 and overlapping the foldedportion 21. Furthermore, metallic molds having various shapes were prepared, and heaters 100 (Samples 2 to 4) having principal surfaces different in configuration from that ofSample 1 were fabricated. Those Samples each had dimensions of 5 mm in thickness, 10 mm in width, and 30 mm in length, and they were different only in configuration of the principal surface fromSample 1. - More specifically, in
Sample 2, thegroove portion 4 in a depth of 50 µm with one side having a length of 2.3 mm was formed in the principal surface in such a configuration that an inner wall surface at the inner side is inclined more moderately than an inner wall surface at the outer side. InSample 3, thegroove portion 4 in a depth of 50 µm with one side having a length of 2.3 mm was formed in the principal surface, and theprojection 5 having a height of 20 µm was further formed in a state surrounding thegroove portion 4. InSample 4, thegroove portion 4 in a depth of 50 µm with one side having a length of 2.3 mm was formed in the principal surface, and theprojection 5 having a curved surface with a height of 20 µm at a top thereof was further formed in a state surrounding thegroove portion 4. In addition, Comparative Example 1 in which the principal surface was flat was prepared as a comparative sample. - Next, after putting each of
Samples 1 to 4 and Comparative Example 1, obtained as described above, in a cylindrical die made of carbon, it was hot-pressed at temperature of 1650°C to 1780°C under pressure of 30 MPa to 50 MPa for sintering in a non-oxidizing gas atmosphere of nitrogen gas. - By comparing with the heater of Comparative Example 1, the
heaters 100 ofSamples 1 to 4 representing EXAMPLE of the present invention were confirmed on whether durability was improved. - In more detail, each sample was set in a gas heater, and an ignition temperature of the gas heater was examined. On the basis of the examined result, an endurance test was carried out by repeating a cycle of, after supplying a current for 30 sec at the ignition temperature, raising temperature at the fore end of the ceramic structure up to 1200°C, and then stopping the supply of the current for 60 sec.
- As a result, the
heaters 100 ofSamples 1 to 4 continued the normal operation even after the number of cycles reached 230000 or more. In the heater of Comparative Example 1, however, a crack occurred in the principal surface of theceramic structure 1 near themaximally heating region 10 when the number of cycles reached about 60000. - As another evaluation test, a temperature distribution in a region from the fore end of the
ceramic structure 1 to themaximally heating region 10 was measured by employing a radiation thermometer. In more detail, the temperature distribution in the surface of theceramic structure 1 was measured under the condition that, after raising the temperature at the fore end of theceramic structure 1 up to 1200°C, theceramic structure 1 was left to stand for 5 min in a state keeping application of a voltage. - As a result, in the heater of Comparative Example 1, the temperature in the maximally heating region of the ceramic structure was 1240°C, and the temperature at the fore end of the ceramic structure was 1200°C. In contrast, in the
heater 100 ofSample 1, the temperature in themaximally heating region 10 was 1250°C, the temperature at the fore end was 1230°C, and the temperature in therecess 6 was 1240°C. In theheater 100 ofSample 2, the temperature in themaximally heating region 10 was 1250°C, the temperature at the fore end was 1230°C, and the temperature in thegroove portion 4 was 1240°C. In theheater 100 ofSample 3, the temperature in themaximally heating region 10 was 1250°C, the temperature at the fore end was 1230°C, and the temperature in thegroove portion 4 was 1240°C. In theheater 100 ofSample 4, the temperature in themaximally heating region 10 was 1250°C, the temperature at the fore end was 1230°C, and the temperature in thegroove portion 4 was 1240°C. - As seen from the above results, the temperature difference in the principal surface of the ceramic structure was relatively large, i.e., 40°C, in the heater of Comparative Example 1, while the relevant temperature difference was relatively small, i.e., 20°C, in the
heaters 100 ofSamples 1 to 4. Thus, it was confirmed that unevenness of the temperature distribution in the principal surface of theceramic structure 1 can be reduced by employing the configuration of theheater 100 of the present invention. Consequently, it was also understood that a possibility of the occurrence of a crack in the principal surface of theceramic structure 1 can be reduced even with repeated use of theheater 100. - As still another evaluation test,
Samples 2 to 4 and Comparative Example 1 were each set inside a casing for the test, the casing being provided with a gas inlet. While continuously supplying gas to flow into the casing, measurement was performed on a time until the gas was ignited after starting supply of a current to each of theheaters 100 ofSamples 2 to 4 and the heater of Comparative Example 1, and a time until extinction after stopping the supply of the current. The gas was prepared by evaporating diesel fuel. As a result, in theheaters 100 ofSamples heaters 100 ofSamples - The above result is presumably attributable to the fact that, since the
heater 100 ofSample 2 includes thegroove portion 4 in which the inner wall surface at the inner side is inclined more moderately than the inner wall surface at the outer side, the flow of the gas incoming from the outer peripheral side of thegroove portion 4 is moderated near the inner wall surface at the inner side and the gas is more likely to stay in thegroove portion 4, whereby ignitibility is improved. RegardingSample 3, it is thought that, because of including theprojection 5 that surrounds thegroove portion 4, the gas is even more likely to stay in thegroove portion 4, whereby ignitibility is improved. - Moreover, comparing the time taken for the extinction after the end of heating between the heater of Comparative Example 1 and the
heater 100 ofSample 4, the time until the extinction after stopping the supply of the current was about 70 sec in theheater 100 ofSample 4, while the time until the extinction was about 100 sec in the heater of Comparative Example 1. Such a result is presumably attributable to the fact that, because of theprojection 5 having the curved shape, when the gas is supplied and flows around theheater 100, the gas can more easily flow into the inside surrounded by theprojection 5, whereby the gas can be efficiently combusted at the inside surrounded by theprojection 5. -
- 1: ceramic structure
- 10: maximally heating region
- 2: heating resistor
- 21: folded portion
- 22: linear portion
- 3: power feeder
- 4: groove portion
- 5: projection
- 6: recess
- 7: lead terminal
- 100: heater
Claims (7)
- A heater comprising a ceramic structure, and a heating resistor embedded in the ceramic structure and including a folded portion, wherein the ceramic structure includes, in a surface facing the folded portion, a groove portion that surrounds the folded portion in opposing relation.
- The heater according to Claim 1, wherein the groove portion has a circular ring shape.
- The heater according to Claim 1 or 2, wherein the groove portion has a curved shape when looking at a cross-section of the ceramic structure sectioned in a direction perpendicular to the surface of the ceramic structure.
- The heater according to any one of Claims 1 to 3, wherein a wall surface of the groove portion is inclined more moderately at an inner peripheral side than at an outer peripheral side.
- The heater according to any one of Claims 1 to 4, wherein a projection is continuously formed along an outer periphery of the groove portion.
- The heater according to Claim 5, wherein the projection has a curved shape when looking at a cross-section of the ceramic structure sectioned in a direction perpendicular to the surface of the ceramic structure.
- A heater comprising a ceramic structure, and a heating resistor embedded in the ceramic structure and including a folded portion, wherein the ceramic structure includes a recess in a region of a surface facing the folded portion, the region overlapping the folded portion.
Applications Claiming Priority (2)
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JP2012284051 | 2012-12-27 | ||
PCT/JP2013/085105 WO2014104293A1 (en) | 2012-12-27 | 2013-12-27 | Heater |
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EP2941090A1 true EP2941090A1 (en) | 2015-11-04 |
EP2941090A4 EP2941090A4 (en) | 2016-08-17 |
EP2941090B1 EP2941090B1 (en) | 2018-02-21 |
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EP13869090.4A Active EP2941090B1 (en) | 2012-12-27 | 2013-12-27 | Heater |
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EP (1) | EP2941090B1 (en) |
JP (1) | JP5960845B2 (en) |
WO (1) | WO2014104293A1 (en) |
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DE2022282C3 (en) * | 1970-05-06 | 1980-05-29 | Villamosipari Kutato Intezet, Budapest | Process for the manufacture of an electrical heating element |
JPS54150727U (en) * | 1978-04-14 | 1979-10-19 | ||
JPH0129427Y2 (en) * | 1985-12-27 | 1989-09-07 | ||
JPH03183942A (en) * | 1989-12-14 | 1991-08-09 | Ngk Spark Plug Co Ltd | Heater structure of sensor |
DE69424478T2 (en) * | 1993-07-20 | 2001-01-18 | Tdk Corp | Ceramic heating element |
JP4555151B2 (en) | 2004-06-25 | 2010-09-29 | 日本特殊陶業株式会社 | Ceramic heater and glow plug equipped with the ceramic heater |
EP1612486B1 (en) * | 2004-06-29 | 2015-05-20 | Ngk Spark Plug Co., Ltd | Glow plug |
FR2898960B1 (en) * | 2006-03-21 | 2008-05-30 | Renault Sas | PREHEATING PLUG FOR COMBUSTION ENGINE |
JP5171335B2 (en) * | 2008-03-25 | 2013-03-27 | 日本特殊陶業株式会社 | Ceramic heater and glow plug |
-
2013
- 2013-12-27 EP EP13869090.4A patent/EP2941090B1/en active Active
- 2013-12-27 JP JP2014554592A patent/JP5960845B2/en active Active
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EP2941090B1 (en) | 2018-02-21 |
JPWO2014104293A1 (en) | 2017-01-19 |
JP5960845B2 (en) | 2016-08-02 |
EP2941090A4 (en) | 2016-08-17 |
WO2014104293A1 (en) | 2014-07-03 |
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