JP6502227B2 - Ceramic heater - Google Patents

Description

  The present invention relates to a ceramic heater for use in, for example, a hot-water-washed toilet seat, a fan heater, an electric water heater, and a 24-hour bath, and in particular, a metal annular flange is externally fitted on a ceramic heater body. The present invention relates to a ceramic heater having a different structure.

  Generally, a heat exchange unit having a resin container (heat exchanger) is used for the hot water cleaning toilet seat. A cylindrical ceramic heater is attached to the heat exchange unit in order to warm the cleaning water contained in the heat exchanger.

  As this type of ceramic heater, an annular ceramic flange made of a flat plate is externally fitted to a cylindrical ceramic heater main body, and a heater main body and the flange are joined via glass. There is.

  Also, in recent years, in order to improve the airtightness and strength (bonding strength) between the heater body and the flange, etc., an annular metal flange made of a flat plate is removed from the cylindrical ceramic heater body. It has been proposed to fit and connect the heater body and the flange with a brazing material (see, for example, Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 11-74063 JP-A-9-283197

  However, when welding and joining the ceramic heater main body and the metal flange described above via glass, the molten glass does not uniformly reach the gap between the heater main body and the flange, which causes the bonding strength. There is a problem of shortage and water leakage. That is, the wettability to the glass is different between the ceramic and the metal, and specifically, the ceramic heater main body has higher wettability to the glass than the metal flange. Therefore, the melted glass first spreads on the outer peripheral surface of the heater body, and then the inner surface of the hole of the flange starts to get wet. However, when the dimension of the gap between the outer peripheral surface of the heater body and the inner surface of the hole of the flange is substantially uniform over the circumferential direction, the wetting and spreading to the flange side tends to be delayed, and the molten glass does not extend over the entire circumferential direction. Sometimes. As a result, the gap is not completely filled with the glass, which causes problems such as insufficient bonding strength and water leakage due to the deterioration of airtightness. Therefore, in the above case, it has been difficult to provide the ceramic heater with sufficient performance.

  The present invention has been made in view of the above problems, and an object thereof is to provide a ceramic heater excellent in airtightness and bonding strength between a heater main body and a flange bonded through glass. .

  As means for solving the above problems (means 1), there is provided a ceramic heater comprising a cylindrical heater body made of ceramic and a metal annular flange externally fitted to the heater body. The flange has a hole penetrating the first surface and the second surface, and has a concave portion on the first surface side, and the concave portion has a glass reservoir filled with glass. The flange and the heater main body are joined via the glass disposed in the glass reservoir, and the heater is disposed between the outer peripheral surface of the heater main body and the inner surface of the hole of the flange. A gap of nonuniform dimensions is formed along the circumferential direction of the main body, and the maximum dimension of the gap is 0.8 mm or less, and the difference between the maximum dimension and the minimum dimension of the gap is 0.1 mm or more There is a ceramic heater wherein there.

  According to the invention described in means 1, a gap having nonuniform dimensions is formed along the circumferential direction of the heater body between the outer peripheral surface of the heater body and the inner surface of the hole of the flange, and the gap is maximum There are locations that will be the dimensions and locations that will be the minimum dimensions. Therefore, the melted glass starts to wet and spread from the place where the gap has the smallest dimension, that is, the place where the outer peripheral surface of the heater main body and the inner surface of the hole of the flange come closest to each other. Then, the melted glass gradually wraps around from the location where the gap is the smallest dimension to the location where the gap is the largest dimension, and as a result, it is sufficiently spread over the entire circumferential direction of the gap. Therefore, since the gap is completely filled with the glass, it is possible to provide a ceramic heater excellent in airtightness and bonding strength between the heater body and the flange.

  Here, if the difference between the largest dimension and the smallest dimension of the gap is less than 0.1 mm, the dimension difference between the two is too small, and the location of the smallest dimension of the gap is unlikely to be the starting point of wet spreading. There is a possibility that it does not go around the whole circumferential direction. In addition, if the largest dimension of the gap is more than 0.8 mm, the glass does not wrap around to the location where the largest dimension of the gap is reached, and there is a possibility that the location can not be filled with the molten glass. Therefore, in order to improve the airtightness and the bonding strength, as described above, the maximum dimension of the gap is 0.8 mm or less, and the difference between the maximum dimension and the minimum dimension of the gap is 0.1 mm or more. It is essential.

  When the heater main body has a groove extending along the axial direction on the outer peripheral surface, the maximum dimension of the region excluding the groove in the gap is preferably 0.8 mm or less.

  In the ceramic heater of the above means, for example, the central axis of the flange is disposed eccentrically with respect to the central axis of the heater main body in order to form a gap of nonuniform dimensions along the circumferential direction of the heater main body. May be The amount of eccentricity at this time is not particularly limited, but for example, 0.05 mm or more is suitable, and more preferably 0.05 mm to 0.5 mm. Alternatively, the central axis of the flange may be arranged to be inclined with respect to the central axis of the heater body. The inclination angle at this time is not particularly limited, but for example, 0.1 ° or more is preferable, and 0.1 ° to 3.0 ° is more preferable.

  In addition, in order to form a gap of non-uniform dimension along the circumferential direction of the heater main body, the cross-sectional shape of the hole of the flange or the cross-sectional shape of the outer peripheral surface of the heater main body may be non-circular. Specifically, for example, when the cross-sectional shape of the hole portion of the flange is circular, the cross-sectional shape of the outer peripheral surface of the heater main body (except for the groove portion) may be substantially elliptical. When the cross-sectional shape (but excluding the groove portion) of the outer peripheral surface of the heater main body is circular, the cross-sectional shape of the hole portion of the flange may be substantially elliptical.

  In the ceramic heater of the above means, the glass reservoir portion of the concave portion of the flange is filled with glass, and the heater body and the flange are joined via the glass. Therefore, when manufacturing the ceramic heater of this configuration, for example, a glass reservoir may be filled with a glass material, and the heater body and the flange may be welded and joined via the glass. Therefore, compared with the case where the conventional joining method by brazing is performed, it can be set as the ceramic heater which can be manufactured easily.

  Moreover, when the flange of the said means which has a concave-shaped part is used, compared with the case where it joins only with the narrow inner peripheral surface of the width of the hole of a flat flange, for example, It is welded to the outer peripheral surface of the heater body and the inner surface of the hole of the flange over a wide area along the direction. Thereby, high air tightness and bonding strength are provided between the heater body and the flange.

  Here, the “glass reservoir” refers to a portion of the concave portion capable of storing glass (a portion filled with glass and stored).

  The flange is an annular flange made of metal, and examples of the metal material forming the flange include a single metal and an alloy. Preferred examples of such a single metal or alloy include stainless steels such as SUS304 and SUS430, which are metals containing chromium and iron. The reason for using stainless steel is that stainless steel is excellent in heat resistance, corrosion resistance, mechanical strength, and adhesion to glass is high. In addition, simple metals such as iron, copper, chromium and nickel, and alloys such as chromium steel, iron-nickel and iron-nickel-cobalt can be selected as the metal material for forming the flange.

  Here, when the flange is made of a metal containing chromium, the chromium content on the surface of the flange is preferably larger than the chromium content in the inside of the flange. In this case, since the wettability of the glass on the surface of the flange is improved, the glass can be easily bonded firmly to the surface of the flange, and the airtightness and the bonding strength are improved. Further, the presence of a large amount of chromium on the surface of the metal flange has the advantage of improving the corrosion resistance. The chromium on the surface of the flange may be present as a single metal or may be present as an oxide.

  The flange is preferably formed in a cup-shaped bent state so that the plate material has a concave portion, and the glass is formed to fill at least a part of the inside of the cup serving as a glass reservoir. Is preferred. With such a structure, the flange can be easily manufactured from the plate material by, for example, pressing.

  In the ceramic heater of the above means, the thermal expansion coefficient of the metal constituting the flange is preferably larger than the thermal expansion coefficient of the ceramic constituting the heater body and the thermal expansion coefficient of the glass. Therefore, when the temperature at the time of welding of the glass (welding temperature) decreases, for example, to normal temperature, stress can be applied to the inner glass and the heater main body from the outer flange. By the action of this stress, airtightness and joint strength can be enhanced.

Here, the thermal expansion coefficient of the metal forming the flange are not particularly limited, may be employed a value in the range of, for example, ^{100 × 10 -7 / K~200 × 10} -7 / K. As the thermal expansion coefficient and the thermal expansion coefficient of the glass ceramic constituting the heater body, both are not particularly limited, the value of, for example, within a range of ^{50 × 10 -7 / K~90 × 10} -7 / K It can be adopted. In addition, it is preferable that the thermal expansion coefficient of glass is larger than the thermal expansion coefficient of a ceramic, and in this case, airtightness and joining strength can be further improved.

  In the case of a ceramic heater, the flange is preferably joined in a state where compressive residual stress is applied to the glass and the heater body, and in this case, airtightness and joint strength can be further improved.

  In the ceramic heater of the above means, as a ceramic for forming the heater main body, for example, alumina, aluminum nitride, silicon nitride, boron nitride, zirconia, titania, mullite and the like can be mentioned as preferable examples. The heater main body includes a heating element (heater pattern layer) made of, for example, tungsten, molybdenum, tantalum or the like.

The glass used for the ceramic heater of the above means is not particularly limited. For example, B ₂ O ₃ · SiO ₂ · Al ₂ O ₃ system, SiO ₂ · Na ₂ O system, SiO ₂ · PbO system, SiO ₂ · Al ₂ O ₃ · BaO-based glasses, or component-based glasses in which the respective components are replaced, etc. may be mentioned as preferable examples.

  The depth (depth in the axial direction) of the glass reservoir in which the glass is stored is preferably set, for example, in the range of 1 mm to 20 mm, and the depth of the glass may be set, for example, 2 mm or more preferable.

(A) is a front view of the ceramic heater in the embodiment embodying the present invention, (b) is a partially cutaway view when the flange and the glass portion in the same ceramic heater are cut along the axial direction. The top view which permeate | transmits and shows the glass part of the ceramic heater of embodiment. Explanatory drawing which expand | deploys and shows the heater pattern layer side of the ceramic layer of the ceramic heater of embodiment. (A) is a top view which shows the flange of the ceramic heater of embodiment, (b) is AA sectional drawing of (a). The principal part expansion fracture side view when the flange in the ceramic heater of an embodiment, and the portion of glass are cut along the direction of an axis. (A)-(f) is an explanatory view showing a manufacturing method of a ceramic heater of an embodiment. The top view shown penetrating the glass part of the ceramic heater of another embodiment. The schematic sectional view when the flange in the ceramic heater of another embodiment and a heater main body are cut | disconnected along an axial direction.

  Hereinafter, a ceramic heater according to an embodiment of the present invention and a method of manufacturing the same will be described with reference to FIGS. 1 to 6.

  The ceramic heater 11 of the present embodiment is used, for example, in a heat exchanger of a heat exchange unit of a warm water washing toilet seat to warm the washing water.

  As shown in FIGS. 1 and 2, the ceramic heater 11 includes a cylindrical ceramic heater body 13 and a metal annular flange 15 fitted on the heater body 13. . The heater main body 13 is composed of a ceramic tube 17 and a ceramic layer 19 covering almost the entire outer periphery of the ceramic tube 17. In the present embodiment, the outer diameter of the ceramic tube 17 is set to 10 mmφ, the inner diameter is set to 8 mmφ, and the length is 65 mm, and the thickness of the ceramic layer 19 is set to 0.5 mm and the length 60 mm. Since the ceramic layer 19 does not completely cover the outer periphery of the ceramic tube 17, the outer peripheral surface 14 of the heater main body 13 is formed with a groove 21 having a width of 1 mm and a depth of 0.5 mm extending along the axial direction. There is.

The ceramic tube 17 and the ceramic layer 19 constituting the heater main body 13 are made of alumina, for example. The thermal expansion coefficient of alumina is in the range of 50 × 10 ⁻⁷ / K to 90 × 10 ⁻⁷ / K, and 70 × 10 ⁻⁷ / K (30 ° C. to 380 ° C.) in this embodiment. It has become.

  As shown in FIG. 3, a heater pattern layer 22 and a pair of internal terminals 23 are formed in a serpentine pattern on the inner peripheral surface (surface on the ceramic tube 17 side) or inside of the ceramic layer 19. These internal terminals 23 are electrically connected to external terminals 25 (see FIG. 1) at the end of the outer peripheral surface of the ceramic layer 19 through via conductors and the like (not shown).

  As shown in FIG. 4, the flange 15 is an annular member made of metal such as stainless steel, for example, and the central portion of the plate is bent toward the first surface S1 to be concave (cup shape). It is. More specifically, the flange 15 of the present embodiment is formed, for example, by bending a plate having a thickness of 1 mm. At a central portion of the plate member, a hole 27 is formed which passes through a first surface S1 which is an inner surface and a second surface S2 which is an outer surface. In the present embodiment, the inner diameter of the opening side (that is, the upper side of FIG. 4B) of the concave portion 16 is set to, for example, 16 mmφ. On the other hand, the inner diameter of the bottom side (that is, the lower side of FIG. 4B) of the concave portion 16, that is, the inner diameter of the hole 27 is set to 12 mmφ, for example.

  The overall height H1 (vertical direction in FIG. 4B) of the flange 15 is 6 mm, for example, and the bottom 29 curved at a radius r (for example 1.5 mm) and upward from the bottom 29 (axial direction And a cylindrical side 31 extending perpendicularly thereto. For example, the height H2 of the bottom portion 29 is 1.5 mm, and the height H3 of the side portion 31 is 4.5 mm. Moreover, the radius r means the radius in the cross section along the axial direction.

The thermal expansion coefficient of the metal forming the flange 15 is a value within the range of ^{100 × 10 -7 / K~200 × 10} -7 / K. For example, when the flange 15 is made of SUS304 (main component is Fe, Ni, Cr), the thermal expansion coefficient thereof is 178 × 10 ⁻⁷ / K (30 ° C. to 380 ° C.), SUS 430 (main component Is made of Fe, Cr), the thermal expansion coefficient thereof is 110.times.10.sup.- ⁷ / K (30.degree. C. to 380.degree. C.).

  In this embodiment, as shown in FIG. 5, in the concave portion 16 of the flange 15, the glass 33 is a space surrounded by the outer peripheral surface of the heater main body 13 and the first surface S1 which is the inner surface of the flange 15. It is considered as a glass reservoir 35 to be filled. In FIGS. 1 and 2, the portion of the glass 33 is hatched.

  The height H4 (vertical direction in FIG. 5) of the glass reservoir 35 is set, for example, in the range of 1 mm to 20 mm, and is 5 mm in the present embodiment. The width X (i.e., the radial length of the opening) X of the side portion 31 of the glass reservoir 35 is set, for example, in the range of 1 mm to 20 mm, and is 2 mm in the present embodiment.

  In the glass reservoir 35, glass 33 is filled to 1/3 or more of the height H4 of the glass reservoir 35, and the heater body 13 and the flange 15 are welded and joined via the glass 33. The height (dimension along the axial direction of the heater main body 13) H5 of the glass 33 is set, for example, in the range of 1 mm to 19 mm.

As the glass 33, for example, _{Na 2 O · Al 2 O 3} · B 2 O 3 · SiO 2 -based glass of the so-called _{Al 2 O 3 · B 2 O} 3 · SiO 2 -based glass of (borosilicate glass) is used ing. The thermal expansion coefficient of the glass 33 is, for example, a value within the range of 50 × 10 ⁻⁷ / K to 90 × 10 ⁻⁷ / K (30 ° C. to 380 ° C.), and in the present embodiment, 62 × 10 ⁻⁷ / K (30 ° C. to 380 ° C.).

  As shown in FIGS. 4 and 5, a gap 39 having a dimension Y exists between the inner surface 28 of the hole 27 located on the bottom 29 side of the recessed portion 16 and the outer peripheral surface 14 of the heater body 13. ing. In the present embodiment, the gap 39 has an uneven dimension along the circumferential direction of the heater body 13. The maximum dimension Ymax of the area excluding the groove 21 in the gap 39 is set to be 0.8 mm or less. Further, the difference between the maximum dimension Ymax and the minimum dimension Ymin of the gap 39 is set to be 0.1 mm or more. A portion of the glass 33 filled in the glass reservoir 35 on the first surface S1 side axially flows along the outer peripheral surface 14 of the heater main body 13 along the gap 39, and is located further below the lower end of the second surface S2. It has reached to.

  Next, a method of manufacturing the ceramic heater 11 of the present embodiment will be described based on FIG.

  First, as shown in FIG. 6A, the cylindrical alumina ceramic tube 17 is temporarily sintered.

  Further, as shown in FIG. 6B, a high melting point metal such as tungsten is printed on the surface of the alumina ceramic sheet 51 or inside the laminated sheet. Thereby, a pattern 53 to be the heater pattern layer 22, the internal terminal 23, and the external terminal 25 is formed later.

  Next, a ceramic paste (alumina paste) is applied to one side surface of the ceramic sheet 51, and the ceramic sheet 51 is wound around and bonded to the outer peripheral surface of the ceramic tube 17 as shown in FIG. Baking. Thereafter, the external terminals 25 are plated with nickel to form the heater body 13.

  Next, a plate material made of stainless steel is press-formed using a mold to form a cup-shaped flange 15, and this flange 15 is formed into a predetermined shape as shown in FIG. 6 (d). Externally fit in the mounting position of. In this state, the heater body 13 and the flange 15 are supported by a jig not shown. Here, in order to form the gap 39 having an uneven dimension along the circumferential direction of the heater main body 13, here, the central axis C1 of the flange 15 is slightly (for example 0.2 mm to about the central axis C2 of the heater main body 13). Arranged in an eccentric state (about 0.3 mm) (see FIG. 4)

  Further, the above-mentioned glass material made of borosilicate glass is press-formed into a ring shape, and this is calcined at 640 ° C. for 30 minutes to prepare a calcined glass material 55. Then, as shown in FIG. 6E, a ring-shaped calcined glass member 55 is disposed in the glass reservoir 35 between the heater main body 13 and the flange 15.

Next, the one in this state is put into a continuous furnace for firing, and the heater main body 13 and the flange 15 are glassed. Specifically, the calcined glass material 55 is melted by heating the inside of the continuous furnace at a welding temperature (1015 ° C.) for a predetermined time under a reducing atmosphere (for example, N ₂ + 5% H ₂ ). Thereafter, the calcined glass material 55 is cooled to a normal temperature (for example, 25 ° C.) and solidified to weld and fix the heater main body 13 and the flange 15 via the glass 33, thereby completing the ceramic heater 11.
<Example of experiment>

  Hereinafter, an experimental example performed to evaluate the performance of the ceramic heater 11 of the present embodiment will be described.

Here, in manufacturing the ceramic heater 11 by the above manufacturing method, the maximum dimension Ymax of the area excluding the groove 21 in the gap 39 is 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm. . In addition, the difference between the maximum dimension Ymax and the minimum dimension Ymin of the gap 39 was set to 0.05 mm, 0.1 mm, 0.2 mm, and 0.3 mm. Thus, the test area was set, 10 ceramic heaters 11 were put into a continuous furnace per test area, and glass attachment was performed. And the airtightness test was done about the product sample of the obtained ceramic heater 11, and the presence or absence ("airtightness defect generation | occurrence | production number / number of injection | throwing-in numbers (10 each)") was investigated. The results are shown in Table 1. In the air tightness inspection, a helium leak detector of at least 1 × 10 ⁻⁸ Pa · m ³ / s was used as “problem” using a conventionally known helium leak detector.

  As shown in Table 1, the test area in which the maximum dimension Ymax of the region excluding the groove 21 in the gap 39 is 0.8 mm or less and the difference between the maximum dimension Ymax of the gap 39 and the minimum dimension Ymin is 0.1 mm or more In the example, no airtightness problems occurred. On the other hand, in the test section where the maximum dimension Ymax is 1.0 mm, the airtightness failure occurred in any of the range where the difference between the maximum dimension Ymax and the minimum dimension Ymin is 0.05 mm to 0.3 mm. Moreover, in the test section in which the difference between the maximum dimension Ymax and the minimum dimension Ymin is 0.05 mm, the airtightness failure occurred even when the maximum dimension Ymax was any in the range of 0.6 mm to 1.0 mm.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) In the ceramic heater 11 according to the present embodiment, a gap having an uneven dimension along the circumferential direction of the heater body 13 between the outer peripheral surface 14 of the heater body 13 and the inner surface 28 of the hole 27 of the flange 15 39 are formed. Further, in the gap 39, there are a portion having the maximum dimension Ymax and a portion having the minimum dimension Ymin. Therefore, the molten glass 33 starts to wet and spread starting from the place where the gap 39 has the minimum dimension Ymin, that is, the place where the outer peripheral surface 14 of the heater main body 13 and the inner surface 28 of the hole 27 of the flange 15 are closest to each other. Then, the melted glass 33 gradually wraps around from the portion where the minimum dimension Ymax of the gap 39 is to the portion where the maximum dimension Ymax is the gap 39, and as a result, sufficiently spreads over the entire circumferential direction of the gap 39. Therefore, since the gap 39 is completely filled with the glass 33, it is possible to provide the ceramic heater 11 excellent in airtightness and bonding strength between the heater main body 13 and the flange 15.

  (2) In the ceramic heater 11 of the present embodiment, the glass reservoir 35 of the concave portion 16 of the flange 15 is filled with the glass 33, and the heater body 13 and the flange 15 are joined via the glass 33. Therefore, when manufacturing the ceramic heater 11 of this configuration, the glass reservoir 35 may be filled with the material of the glass 33, and the heater body 13 and the flange 15 may be welded and joined via the glass 33. Therefore, the ceramic heater 11 can be easily manufactured as compared with the case where the conventional joining method by brazing is performed. Further, the flange 15 of the present embodiment is bent in a cup shape, and the glass 33 fills the inside of the cup serving as the glass reservoir 35. Therefore, if it is such a structure, flange 15 can be easily manufactured from board material by press processing etc., for example.

  (3) In the ceramic heater 11 of the present embodiment, the flange 15 having the concave portion 16 is used. For this reason, compared with the case where conventional flat flanges are joined, the glass 33 disposed in the glass reservoir 35 covers the outer peripheral surface 14 of the heater main body 13 and the hole of the flange 15 over a wide area along the axial direction. It is welded to the inner surface 28 of 27. Thereby, high airtightness and joint strength are provided between the heater main body 13 and the flange 15.

  (4) In the ceramic heater 11 of the present embodiment, the thermal expansion coefficient of the metal (stainless steel) forming the flange 15 is greater than the thermal expansion coefficient of the ceramic (alumina) forming the heater main body 13 and the thermal expansion coefficient of the glass 33 It is getting bigger. Therefore, when the temperature drops from the temperature at the time of welding of the glass 33 to normal temperature, stress can be applied from the outer flange 15 to the inner glass 33 and the heater main body 13. By the action of this stress, airtightness and joint strength can be enhanced. In addition, since the residual stress is applied to the glass 33 and the heater main body 13 after the flange 15 is manufactured, the airtightness and the bonding strength can be further improved.

  (5) In the ceramic heater 11 of the present embodiment, the flange 15 is made of stainless steel containing chromium and iron, and the chromium content of the surface of the flange 15 is larger than the chromium content of the inside of the flange 15 through the firing step. It has become. Therefore, as a result of the wettability of the glass 33 on the surface of the flange 15 being improved, the glass 33 can be easily joined firmly to the surface of the flange 15, and the airtightness and the bonding strength are improved. Further, the presence of a large amount of chromium on the surface of the metal flange 15 can improve the corrosion resistance.

  The embodiment of the present invention may be modified as follows.

  In the ceramic heater 11 of the above embodiment, the cross-sectional shape of the hole 27 of the flange 15 and the cross-sectional shape of the outer peripheral surface 14 of the heater body 13 (except for the groove 21) are both circular. C2 was disposed eccentrically with respect to the central axis C1 of the heater body 13. On the other hand, as in the ceramic heater 11A of another embodiment shown in FIG. 7, for example, the cross-sectional shape (but excluding the groove 21) of the outer peripheral surface 14 of the heater main body 13 is circular, while the hole of the flange 15A. The cross-sectional shape of 27 may be a substantially elliptical shape. Also in this case, it is possible to form a gap 39 of nonuniform size along the circumferential direction of the heater main body 13. Although not shown, when the cross-sectional shape of the hole 27 of the flange 15 is circular, the cross-sectional shape (except for the groove 21) of the outer peripheral surface 14 of the heater main body 13 may be substantially elliptical.

  In the ceramic heater 11 of the above embodiment, the central axis C2 of the flange 15 is disposed slightly eccentric to the central axis C1 of the heater main body 13. However, the present invention is not limited to this. For example, as in the ceramic heater 11B of another embodiment shown in FIG. 8, the central axis C2 of the flange 15 may be disposed in a state of being inclined with respect to the central axis C1 of the heater main body 13. Also in this case, it is possible to form a gap 39 of nonuniform size along the circumferential direction of the heater main body 13.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiments described above will be listed below.

(1) In the above means 1, the central axis of the flange is disposed eccentrically with respect to the central axis of the heater main body.
(2) In the above means 1, the central axis of the flange is disposed eccentrically with respect to the central axis of the heater main body by 0.05 mm or more.
(3) In the above means 1, the central axis of the flange is arranged to be inclined with respect to the central axis of the heater main body.
(4) In the above means 1, the central axis of the flange is disposed at an angle of 0.1 ° or more with respect to the central axis of the heater main body.
(5) In the above means 1, the hole portion of the flange or the outer peripheral surface of the heater main body has a substantially elliptical cross section.
(6) In the above means 1, the thermal expansion coefficient of the metal forming the flange is larger than the thermal expansion coefficient of the metal forming the heater main body and the thermal expansion coefficient of the glass.

11, 11A: ceramic heater 13: heater main body 14: outer peripheral surface of heater main body 15, 15A: flange 16: concave portion 27: hole 28: inner surface of hole 33: glass 35: glass reservoir 39: gap d1: flange Radial direction S1 ... First surface S2 ... Second surface Ymax ... Maximum dimension of clearance Ymin ... Maximum dimension of clearance

Claims (5)

A ceramic heater comprising: a ceramic cylindrical heater body; and a metal annular flange externally fitted to the heater body.
The flange has a hole penetrating the first surface and the second surface, and has a concave portion on the first surface side,
The concave portion includes a glass reservoir filled with glass, and the flange and the heater main body are joined via the glass disposed in the glass reservoir.
Between the outer peripheral surface of the heater main body and the inner surface of the hole of the flange, a gap having nonuniform dimensions is formed along the circumferential direction of the heater main body,
A ceramic heater, wherein the largest dimension of the gap is 0.8 mm or less, and the difference between the largest dimension and the smallest dimension of the gap is 0.1 mm or more.   The ceramic according to claim 1, wherein the heater main body has a groove extending along the axial direction on the outer peripheral surface, and a maximum dimension of a region excluding the groove in the gap is 0.8 mm or less. heater.   The ceramic heater according to claim 1, wherein the flange is made of a metal containing chromium.   The ceramic heater according to any one of claims 1 to 3, wherein the flange is made of stainless steel.   The flange is formed in a state in which the plate is bent in a cup shape so as to have the concave portion, and the glass is formed in a state in which at least a part of the inside of the cup is filled. The ceramic heater according to any one of claims 1 to 4, characterized in that:

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