JP2019164940A - Ceramic heater - Google Patents

Abstract

To provide a ceramic heater capable of shortening the time required for the body part to reach a prescribed temperature entirely.SOLUTION: The heating part 20 of a ceramic heater includes multiple longitudinal parts 21 extending in the longitudinal direction of the body part, and multiple coupling parts 22 extending in a direction intersecting the longitudinal parts 21, and connecting the one end sides and the other end sides of the longitudinal parts 21 alternately. At least some of the multiple coupling parts 22 are provided with narrow parts 23 narrower than the longitudinal parts 21.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a ceramic heater.

  Conventionally, ceramic heaters are well known as heat sources in automobile oxygen sensors and glow systems, and as heat sources for petroleum vaporizers such as semiconductor heaters and petroleum fan heaters.

  In the ceramic heater described in Patent Document 1, a heating resistor (heat generating portion) made of a refractory metal is provided in a main body of a rod-shaped ceramic. The heating resistor includes a plurality of longitudinal portions extending in the longitudinal direction of the main body portion, and a plurality of connecting portions that extend in a direction intersecting the longitudinal portions and connect the longitudinal portions.

International Publication No. 2010/071049

  In the conventional ceramic heater, it is required to shorten the time required for the main body to be heated to a predetermined temperature by the heat of the heat generating portion. In particular, it is required to shorten the time required for heating to the predetermined temperature at the tip of the main body.

  However, the main body is easily heated so that locally high temperature portions (heat points) are concentrated in the vicinity of the center of the longitudinal portion of the heat generating portion. Since heat generated by concentration of heat points is not efficiently transferred to the main body, there is a problem that the time required to heat the main body to a predetermined temperature is increased.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a ceramic heater that can shorten the time required for the main body to be heated to a predetermined temperature.

  A ceramic heater that solves the above problem is a ceramic heater comprising a long body portion made of ceramic and a heat generating portion made of a heating resistor formed in the main body portion by a prescribed heat pattern, wherein the heat generation The portion includes a plurality of longitudinal portions extending in the longitudinal direction of the main body portion, and a plurality of connecting portions that extend in a direction intersecting the longitudinal portion and alternately connect one end side and the other end side of the longitudinal portion. It is summarized that at least a part of the connecting portion is provided with a narrow portion having a width smaller than the width of the longitudinal portion.

  According to this configuration, heat is easily generated in the narrow portion provided in the connecting portion, and the heat point generation position of the heat generating portion can be adjusted. Thereby, the temperature difference of a heat-emitting part becomes small and it becomes easy to transfer heat to a main-body part. Therefore, it is possible to shorten the time until the main body reaches the predetermined temperature as a whole. Furthermore, since it can suppress that a heat point concentrates on the longitudinal part of a heat generating part locally, overheating of a heat generating part can be suppressed. As a result, the reliability of the ceramic heater can be improved.

  In the ceramic heater of the present invention, it is preferable that the narrow portion is provided in the connecting portion that connects one end sides of the longitudinal portion. According to this structure, the position of a heat point can be adjusted with respect to the one end side of a longitudinal part.

  In the ceramic heater of the present invention, it is preferable that a ratio of the width of the narrow portion and the width of the longitudinal portion of the connecting portion is within a range of 1: 1.2 to 1: 3. According to this configuration, the main body portion can be easily heated by the heat generating portion, and the heat point generation position can be adjusted. Moreover, it becomes easy to ensure the strength of the narrow portion.

  In the ceramic heater of the present invention, the thickness of the narrow portion of the heat generating portion is configured to be equal to the thickness of the longitudinal portion, and the width of the narrow portion of the heat generating portion is smaller than the width of the longitudinal portion. It is preferable that it is comprised. According to this configuration, since the narrow portion and the longitudinal portion are configured to have the same thickness, a step at the boundary portion between the narrow portion and the longitudinal portion can be eliminated.

  In the ceramic heater of the present invention, it is preferable that the plurality of longitudinal portions are arranged in parallel around the axis of the main body portion. According to this configuration, it is possible to supply power to a plurality of longitudinal portions arranged in parallel around the axis of the main body portion with a pair of power supply portions, and thus the number of power supply portions can be reduced.

  In the ceramic heater of the present invention, at least one of the end portions on the one end side and the end portions on the other end side of the plurality of longitudinal portions is aligned in the axial direction of the main body portion in the circumferential direction of the main body portion. It is preferable that they are arranged. According to this configuration, it is easy to make the temperature distribution of the main body portion constant in the circumferential direction of the main body portion.

  In the ceramic heater of the present invention, the heat generating part easily generates heat, and the position of the heat point of the heat generating part can be adjusted. Thereby, the temperature difference of a heat-emitting part becomes small and it becomes easy to transfer heat to a main-body part. As a result, the time until the main body reaches a predetermined temperature can be shortened.

The perspective view of the ceramic heater of this embodiment. The cross-sectional view of the ceramic heater of the present embodiment (cross-sectional view taken along line 2-2 in FIG. 1). FIG. 3 is a circumferential development view of a heat generating unit and a power feeding unit of the present embodiment. The enlarged view of the heat generating part of this embodiment. The perspective view which shows the 1st printing process of this embodiment. The perspective view which shows the 2nd printing process of this embodiment. The perspective view which shows the sheet | seat material processing process of this embodiment. The perspective view which shows the winding process of this embodiment. The perspective view which shows the state in the middle of the winding process of this embodiment. The perspective view which shows the embedding process process of this embodiment. The top view which shows the heat point of the heat-emitting part in a comparative example. The top view which shows the heat point of the heat generating part in this embodiment. The graph of the measurement result of the position-temperature from the ceramic heater front-end | tip in a comparative example. The graph of the measurement result of the position-temperature from the ceramic heater front-end | tip in Example 1. FIG. The graph of the measurement result of the position-temperature from the ceramic heater front-end | tip in Example 2. FIG. The graph of the measurement result of the position-temperature from the ceramic heater front-end | tip in Example 3. FIG.

An embodiment of a ceramic heater will be described with reference to FIGS.
As shown in FIG. 1, the ceramic heater 1 includes a long main body 10 made of ceramic. The main body 10 has a cylindrical shape. The main body 10 has a large-diameter portion 10A having a large diameter disposed on the distal end side in the axial direction (X-axis direction in FIG. 1) and a small-diameter portion 10B having a small diameter disposed on the proximal end side. .

  As shown in FIGS. 1 and 2, the large-diameter portion 10 </ b> A of the main body 10 is embedded with a heat generating portion 20 made of a resistance heating element and a part of a pair of power feeding portions 30 also made of a resistance heating element. Has been. The main body 10 includes a ceramic core material 12 and a ceramic sheet material 11 wound around the core material 12 so as to form a plurality of layers. The sheet material 11 is laminated along the radial direction of the main body 10. A part of the power feeding unit 30 is exposed on the side surface of the small diameter portion 10B of the main body.

  The heat generating unit 20 includes a plurality of long portions 21 extending in the axial direction of the main body portion 10 (X-axis direction in FIG. 1) and a plurality of connecting portions 22 that connect the long portions 21 located adjacent to each other. The plurality of longitudinal portions 21 extend from the distal end side to the proximal end side of the main body portion 10 along the center line P of the main body portion 10, and are spaced apart from each other around the axis of the main body portion in the cross section of the main body portion 10. It is arranged so that it is open and arranged in a circle. In the axial direction of the ceramic heater 1 (X-axis direction in FIG. 1), the plurality of longitudinal portions 21 are aligned such that the distal end side that is one end side and the proximal end end that is the other end side are aligned. . That is, the end portions on the one end side and the end portions on the other end side of the plurality of longitudinal portions 21 are arranged such that their positions in the axial direction of the main body portion 10 are aligned in the circumferential direction of the main body portion 10.

  As shown in FIG. 3, in the heat generating part 20, the end parts of the longitudinal parts 21 adjacent to each other in the circumferential direction of the main body part 10 are alternately connected by the connecting part 22 on the distal end side and the proximal end side of the main body part 10. As a whole, the wiring pattern is formed into a so-called comb-shaped continuous wiring pattern. Here, in the case of this embodiment, let the connection part 22 of the front end side be the 1st connection part 22a, and let the connection part 22 of the base end side be the 2nd connection part 22b.

  Of the plurality of longitudinal portions 21, the two longitudinal portions 21 located at both ends are connected to a pair of power feeding portions 30 provided in the main body portion 10 on the proximal side in the axial direction from the heat generating portion 20. The power feeding unit 30 has a distal end side embedded in the large diameter portion 10 </ b> A of the main body portion 10 and a proximal end side exposed at the side surface of the small diameter portion 10 </ b> B of the main body portion 10.

  As shown in FIG. 4, the first connecting portion 22 a of the heat generating portion 20 is configured to have the same thickness as the longitudinal portion 21 of the heat generating portion 20, so that the width is smaller than the longitudinal portion 21 of the heat generating portion 20. It is configured. Below, the part comprised so that the width | variety may become smaller than the longitudinal part 21 in the connection part 22 of the heat generating part 20 is made into the narrow part 23. FIG. In the present embodiment, the entire first connecting portion 22 a is a narrow portion 23. Since the heat generating portion 20 has a wiring pattern with a uniform thickness, the cross-sectional area of the heat generating portion 20 is proportional to the width of the heat generating portion 20. In the present embodiment, the ratio “H: D” between the width H of the narrow portion 23 and the width D of the longitudinal portion 21 is set in the range of “1: 1.2” to “1: 3”. More preferably, the ratio “H: D” is preferably set in the range of “1: 1.5” to “1: 2”.

  Here, the width H of the narrow portion 23 is preferably set in the range of 300 to 1000 μm. More preferably, the range of 500-600 micrometers is preferable. Moreover, it is preferable that the thickness of the heat generating part 20 is set to 5 to 100 μm. For calculating the ratio of the cross-sectional areas, the average value of the width H of the narrow portion 23 and the width D of the longitudinal portion 21 can be used. For example, the width H and the width D of the narrow portion 23 and the longitudinal portion 21 can be measured by measuring arbitrary three points using a microscope, and the average values thereof can be used. Moreover, the thickness of the heat generating part 20 can measure arbitrary 3 points | pieces by cross-sectional observation using a scanning electron microscope (SEM), and can use the average value.

  A method for manufacturing the ceramic heater 1 will be described with reference to FIGS. The ceramic heater 1 is manufactured by sequentially performing a wiring pattern forming process, a sheet material processing process, a winding process, and a firing process described below.

(Wiring pattern formation process)
The wiring pattern forming process includes a first printing process, a first drying process, a second printing process, and a second drying process.

[First printing process]
As shown in FIG. 5, the sheet material 11 made of a ceramic material that becomes an insulating ceramic by firing is formed in a rectangular plate shape. In this case, the longitudinal direction of the sheet material 11 is the first direction that is the axial direction of the main body 10, and the short direction of the sheet material 11 is the second direction that is orthogonal to the first direction. The size of the sheet material 11 is set to one unit size according to the production of one ceramic heater 1.

  Then, the 1st wiring pattern (henceforth the 1st wiring pattern 40) which comprises the heat-emitting part 20 is formed in the surface of the sheet | seat material 11 by printing. The first wiring pattern 40 is printed in a region that is biased to one side in both the first direction and the second direction of the sheet material 11, and this region becomes the heat generation region 11a. Further, there is a region where the first wiring pattern 40 is not printed in both the first direction and the second direction of the sheet material 11. What is used for printing the first wiring pattern 40 is a first conductor paste containing a refractory metal material.

  As a ceramic material which comprises the sheet | seat material 11, the ceramic material used for manufacture of the well-known ceramic heater 1 can be used, For example, an oxide ceramic, nitride ceramic, and carbide ceramic are mentioned. Examples of the oxide ceramic include alumina, zirconia, cordierite, and mullite. Examples of the nitride ceramic include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. Examples of the carbide ceramic include silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide. In addition, the ceramic material constituting the sheet material 11 may contain other components such as a binder.

  The refractory metal material contained in the first conductor paste used for the first wiring pattern 40 is not particularly limited, and a refractory metal material used for manufacturing the known ceramic heater 1 can be used. Examples of the refractory metal material include refractory metals such as W, Mo, Ta, Nb, Ti, Re, Ni, and Cr. A method for printing the first wiring pattern 40 is not particularly limited, and examples thereof include known screen printing.

[First drying step]
After the first printing step, the sheet material 11 having the first wiring pattern 40 printed on the surface is dried. Although it does not specifically limit as a drying method, For example, the method of putting the sheet | seat material 11 in an electric dryer and heating can be mentioned.

[Second printing process]
As shown in FIG. 6, by printing a wiring pattern (hereinafter referred to as a second wiring pattern 41) that constitutes a power feeding unit on the surface of the sheet material 11 on which the first wiring pattern 40 is formed in the first printing step. The power feeding unit 30 is formed. The second wiring pattern 41 is printed in a region adjacent to the heat generating region 11a where the first wiring pattern 40 is printed in the first direction of the sheet material 11, and this region becomes the power feeding region 11b. A second conductor paste containing a refractory metal material is used for printing the second wiring pattern 41.

  The refractory metal material contained in the second conductor paste used for the second wiring pattern 41 is not particularly limited as in the case of the first conductor paste used for the first wiring pattern 40. The first conductive paste and the second conductive paste may use the same refractory metal material or different refractory metal materials. A method for printing the second wiring pattern 41 is not particularly limited, and examples thereof include known screen printing.

[Second drying step]
After the second printing step, the sheet material 11 having the second wiring pattern 41 printed on the surface is dried. Although it does not specifically limit as a drying method, For example, the method of putting the sheet | seat material 11 in an electric dryer and heating can be mentioned.

(Sheet material processing process)
As shown in FIG. 6, after the wiring pattern forming step, the deletion region 11d is deleted so that the sheet material 11 on which the first wiring pattern 40 and the second wiring pattern 41 are formed has a specific shape. The deletion area 11d is a blank area 11c that is a non-printing area in the second direction of the sheet material 11 on which the first wiring pattern 40 and the second wiring pattern 41 are not printed, and the deletion area 11d. The region is biased toward the end side. Of the non-printing area of the sheet material 11, the area that has not been deleted as the deletion area 11d becomes the blank area 11c. In the first direction of the sheet material 11, the boundary K1 between the heat generation region 11a and the power supply region 11b is located on the inner side (the heat generation region 11a side) than the boundary K2 between the blank region 11c and the deletion region 11d. For this reason, the electric power feeding area | region 11b is adjacent to both the blank area | region 11c and the deletion area | region 11d in the 2nd direction of the sheet | seat material 11. FIG.

  As shown in FIG. 7, in the sheet material 11 from which the deletion area 11d is deleted, the heat generation area 11a and the power supply area 11b are arranged in the first direction, and the heat generation area 11a and the blank area 11c are in the second direction. And a part of the power supply region 11b protrudes in the first direction. For this reason, the sheet material 11 that has undergone the sheet material processing step has a heat generating region 11a, a power feeding region 11b, and a blank region 11c, and has an L-shaped specific shape as a whole.

(Winding process)
As shown in FIG. 8, the sheet material 11 is turned over so that the printed surface of the first wiring pattern 40 (second wiring pattern 41) comes to the back surface. And the core material 12 is arrange | positioned so that the sheet material 11 may follow the 1st direction of the sheet material 11 in the edge of the sheet material 11 with the heat_generation | fever area | region 11a of the sheet | seat material 11, and the electric power feeding area | region 11b. The sheet material 11 that has undergone the sheet material processing step is wound around the core material 12. The core material 12 is a cylindrical bar made of a ceramic material that becomes an insulating ceramic when fired.

  The length of the core material 12 is substantially equal to the length L1 (see FIG. 7) in the first direction of the portion of the sheet material 11 where the heat generation region 11a and the power feeding region 11b are located, and the first blank region 11c of the sheet material 11 is first. It is longer than the length L2 in the direction. The circumference of the core material 12 is substantially equal to the length L3 in the second direction of the portion of the sheet material 11 where the heat generating region 11a and the power feeding region 11b are located. The length L4 of the blank region 11c in the second direction of the sheet material 11 is longer than the circumference in a state where the sheet material 11 is wound around the core material 12 by one turn.

  The shape of the core material 12 is not particularly limited, and a cylindrical shape, a prismatic shape, a rectangular tube shape, or the like can be employed in addition to the columnar shape. The ceramic material which comprises the core material 12 is not specifically limited, The ceramic material used for manufacture of the well-known ceramic heater 1 can be used. However, it is preferable that the thermal expansion coefficient is close to that of the ceramic material constituting the sheet material 11, and it is more preferable that the ceramic material is the same. Further, the ceramic material constituting the core material 12 may contain other components such as a binder. The core material 12 may be a fired ceramic.

  As shown in FIG. 9, the sheet material 11 is wound around the core material 12 along the second direction so that the heat generating region 11a and the power feeding region 11b are on the outside. The relationship between the circumference of the core material 12 and the length L3 of the sheet material 11 is substantially equal as described above. For this reason, in the state where the sheet material 11 is wound around the core material 12 for one turn, the first wiring pattern 40 and the second wiring pattern 41 are exposed to the outer peripheral side.

  The blank region 11c is further wound around the core material 12 around which the heat generating region 11a and the power feeding region 11b are wound along the second direction. The length of the blank region 11c in the second direction is set so that the core region 12 has three layers of the blank region 11c. The core region 12 around which the heat generating region 11a and the power feeding region 11b are wound has the blank region 11c wound around three rounds.

  FIG. 10 shows the overall configuration of the molded body after the sheet material 11 is wound around the core material 12. The sheet material 11 is formed so as to be L-shaped as a whole by deleting the deletion region 11d, and this sheet material 11 is subjected to a winding process. Therefore, in a state where the sheet material 11 is wound around the core material 12, the blank region 11c covers the entire heat generating region 11a. In addition, the blank area 11c covers the inner side (first wiring pattern 40 side) portion in the first direction in the power feeding area 11b, but does not cover the outer side portion in the first direction. Therefore, an outer portion in the first direction in the power feeding region 11b is exposed to the outside.

(Baking process)
After the winding step, the molded body is fired. By this firing, the formed body is converted into a ceramic and the ceramic heater 1 is obtained. As described above, the sheet material 11 subjected to the winding process has an L shape as a whole. Therefore, the main body 10 is formed in a shape having a large diameter portion 10A and a small diameter portion 10B. The power feeding unit 30 is formed in a shape in which the distal end side is embedded in the large diameter portion 10 </ b> A and the proximal end side is exposed on the side surface of the small diameter portion 10 </ b> B of the main body portion 10.

  The firing conditions in the firing step are not particularly limited, and can be appropriately set according to the application of the ceramic heater 1 or the like. Moreover, you may perform a drying process and a degreasing process before a baking process. In FIG. 2, an interface is shown between the core material 12 and the sheet material 11, but when the core material 12 and the sheet material 11 are made of the same insulating ceramic, The interface with the sheet material 11 can be eliminated.

The operation of the ceramic heater of this embodiment will be described with reference to FIGS.
As shown in FIG. 11, when the width H of the narrow portion 23 and the width D of the longitudinal portion 21 are the same, that is, when the cross-sectional area of the first connecting portion 22a and the cross-sectional area of the longitudinal portion 21 are the same, the longitudinal portion 21 Heat points 50 are concentrated near the center of the area. This is because the ratio of the heat generating portion 20 per unit area in the main body portion 10 is increased near the center of the longitudinal portion 21. Therefore, the exothermic temperature region 52 is formed near the longitudinal center of the ceramic heater, and the high temperature region 51 is formed in the center of the exothermic temperature region 52.

  As shown in FIG. 12, in the present embodiment, the first connecting portion 22 a is formed to be a narrow portion 23. As the width H of the narrow portion 23 decreases, the narrow portion 23 (first connecting portion 22a) easily generates heat. Therefore, the heat point 50 is not generated locally near the center of the longitudinal portion 21, but is also generated on the first connecting portion 22a side. Thereby, the exothermic temperature area | region 52 is formed in the wide range from the longitudinal direction center vicinity of a ceramic heater to the front end side.

The effect of the ceramic heater of this embodiment will be described.
(1) The heat generating portion includes a plurality of longitudinal portions extending in the longitudinal direction of the main body portion, a plurality of connecting portions extending in a direction intersecting the longitudinal portion, and alternately connecting one end side and the other end side of the longitudinal portion. And at least a part of the plurality of connecting portions is provided with a narrow portion having a width smaller than that of the longitudinal portion.

  Since heat is easily generated in the narrow portion provided in the connecting portion, it is possible to generate a heat point also on the connecting portion side of the heat generating portion. Accordingly, the difference in temperature distribution of the ceramic heater is reduced, and the time until the main body reaches a predetermined temperature can be shortened. Moreover, since it can suppress that a heat point concentrates on the center vicinity of the longitudinal part of a heat generating part, the reliability improvement of a ceramic heater is attained.

(2) The narrow portion is provided in a connecting portion that connects one end sides of the longitudinal portion. Therefore, the heat point generation position can be adjusted with respect to one end side of the longitudinal portion.
(3) The cross-sectional area ratio between the narrow portion and the longitudinal portion is in the range of 1: 1.2 to 1: 3. Accordingly, the main body can be easily heated by the heat generating portion, and the heat point generation position can be adjusted. Moreover, it becomes easy to ensure the strength of the narrow portion.

  (4) The narrow portion is configured such that the thickness is equal to the thickness of the longitudinal portion, and the width is configured to be smaller than the width of the longitudinal portion. Since the narrow portion and the longitudinal portion are configured to have the same thickness, the step at the boundary portion between the narrow portion and the longitudinal portion can be eliminated.

  (5) The plurality of longitudinal portions are arranged around the axis of the main body. Therefore, it is possible to feed power to a plurality of longitudinal portions arranged in parallel around the axis of the main body portion with a pair of feeding portions, and thus the number of feeding portions can be reduced.

  (6) At least one of the end portion on one end side and the end portion on the other end side of the plurality of longitudinal portions is arranged such that positions in the axial direction of the main body portion are aligned in the circumferential direction of the main body portion. Therefore, it becomes easy to make the temperature distribution of the main body constant in the circumferential direction of the main body.

This embodiment can be implemented with the following modifications. The present embodiment and the following modifications can be combined and implemented within a technically consistent range.
The thickness and width of the heat generating part can be changed as appropriate according to the application and size of the ceramic heater.

  In the present embodiment, the ratio of the width between the longitudinal portion and the narrow portion can be appropriately changed according to the application and purpose. However, the width of the longitudinal portion is preferably in the range of 1.2 to 3 times the width of the narrow portion because of the difference in temperature distribution and the time to reach the predetermined temperature. Further, in the range of 1.5 times to 2 times, it is advantageous to reduce the difference in temperature distribution.

  -Although the narrow part of this embodiment was comprised so that thickness might become equal to the thickness of a longitudinal part, and the width | variety was comprised smaller than the width | variety of a longitudinal part, it is not limited to this aspect. If the width is configured to be smaller than the width of the longitudinal portion, the shape of the narrow portion can be appropriately selected. As the shape of the narrow portion, for example, the thickness may be configured to be smaller than the thickness of the longitudinal portion, and both the thickness and the width may be configured to be smaller than the longitudinal portion.

-A narrow part may be provided in both the 1st connection part and the 2nd connection part of a heat generating part, and may be provided only in the 1st connection part or the 2nd connection part.
-The narrow part should just be provided in a part of connection part. For example, it may be provided at the connecting portion by skipping one. Moreover, in one connection part, the narrow part may be provided partially. Moreover, you may provide a narrow part in all the connection parts.

  -The edge part of the front end side in the some longitudinal part and the edge part of the base end side may be arrange | positioned in the position which each differs in the axial direction of a main-body part. That is, the end portions on the one end side and the end portions on the other end side of the plurality of longitudinal portions do not have to be arranged at the same position in the axial direction of the main body portion in the circumferential direction of the main body portion.

  -In this embodiment, the shape of a heat-emitting part is not specifically limited. For example, it may be formed in a U-shape consisting of two longitudinal portions and one connecting portion. Further, the number of power feeding units is not limited to two.

  -In this embodiment, the manufacturing method of a ceramic heater is not limited. It can be manufactured by a known manufacturing method.

Hereinafter, examples in which the above embodiment is further embodied will be described.
In the heat generating part described in the embodiment and the other examples, a plurality of ceramic heaters each having a longitudinal part and a first connecting part consisting of a narrow part as a whole were manufactured. These ceramic heaters have different ratios between the width of the longitudinal portion and the width of the narrow portion, and other configurations and manufacturing conditions are the same. Hereinafter, in the obtained ceramic heater of each Example and Comparative Example, it describes about the shape of a longitudinal part and a narrow part.

(Example 1)
A ceramic heater in which the width (D) of the longitudinal portion is 750 μm, the width (H) of the narrow portion is 500 μm, and the width (D) of the longitudinal portion is 1.5 times the width (H) of the narrow portion. Produced. This was used as the ceramic heater of Example 1.

(Example 2)
A ceramic heater in which the width (D) of the longitudinal portion is 600 μm, the width (H) of the narrow portion is 500 μm, and the width (D) of the longitudinal portion is 1.2 times the width (H) of the narrow portion. Produced. This was used as the ceramic heater of Example 2.

(Example 3)
A ceramic heater having a width (D) of the longitudinal portion of 1000 μm, a width (H) of the narrow portion of 500 μm, and a width (D) of the longitudinal portion being twice the width (H) of the narrow portion was produced. . This was used as the ceramic heater of Example 3.

(Comparative example)
A ceramic heater having a longitudinal part width (D) of 500 μm, a narrow part width (H) of 500 μm, and a longitudinal part width (D) equal to the narrow part width (H) was produced. This was used as a ceramic heater of a comparative example.

(Current density measurement)
The current density of the ceramic heaters of the examples and comparative examples was measured. The current density was determined by measuring the current from the tip of the ceramic heater to 0.6 mm, and the results are shown below.

As shown in Table 1, from the results of current density measurement, the current density of the example was 80 W / mm ² or more, and the current density of the comparative example was less than 80 W / mm ² . Also from this result, it was confirmed that heat was easily generated in the examples.

(Heater heat generation confirmation test)
Each ceramic heater was turned on, and after a certain period of time had elapsed since the start of heat generation, the temperature of the heat generating portion at a specific point was measured to verify whether or not a predetermined temperature was reached. This time, it was verified whether or not a specific point of 1 mm from the tip of the ceramic heater reached 850 ° C. 25 seconds after the start of heat generation. A thermoviewer (manufactured by Nippon Avionics, product number: R300SR) was used for the measurement. The measurement results are shown below. Moreover, the temperature in the whole area | region of the ceramic heater of an Example and a comparative example was measured.

As shown in Table 2, from the results of the heater heat generation confirmation test, the temperature at a specific point reached 850 ° C. in the example, but not in the comparative example.

As shown in FIG. 13, in the comparative example, there was no region where the temperature was 900 ° C. or higher in the entire region of the ceramic heater.
As shown in FIGS. 14-16, in the Example, the area | region where temperature was 900 degreeC or more was confirmed. As described above, in the example, it was confirmed that the time to reach the predetermined temperature was shortened and the temperature was efficiently increased.

(Temperature cycle test)
A voltage was applied to the ceramic heaters of Examples and Comparative Examples, and after heating to 800 ° C., a constant voltage was applied for 100 hours. The ceramic heater which completed the voltage application for 100 hours was operated, the electric current value of the ceramic heater was measured, and this was made into the initial electric current value.

  Next, the temperature cycle of heating the ceramic heater from room temperature to 800 ° C., stopping the heating 3 minutes after reaching 800 ° C., and returning to room temperature as one cycle was repeated 100 times. After heating the ceramic heater which passed 100 temperature cycles to 800 degreeC, the fixed voltage was applied for 100 hours. The ceramic heater which completed the voltage application for 100 hours was operated, the electric current value of the ceramic heater was confirmed, and this was made into the electric current value after a temperature cycle.

  In Examples 1 to 3, the reduction rate of the current value after the temperature cycle was less than 10% with respect to the initial current value. In the comparative example, the decrease rate of the current value after the temperature cycle was 10% or more with respect to the initial current value. Thus, it was confirmed that the reliability of the example was improved as compared with the comparative example.

DESCRIPTION OF SYMBOLS 1 ... Ceramic heater, 10 ... Main body part, 20 ... Heat generating part, 21 ... Longitudinal part, 22 ... Connection part, 22a ... 1st connection part, 22b ... 2nd connection part, 23 ... Narrow part, 30 ... Power feeding part.

Claims (6)

A long main body made of ceramic;
A ceramic heater provided with a heat generating part made of a heat generating resistor formed by a prescribed heat pattern in the main body part,
The heating part is
A plurality of longitudinal portions extending in the longitudinal direction of the main body portion;
A plurality of connecting portions that extend in a direction intersecting with the longitudinal portion and alternately connect one end side and the other end side of the longitudinal portion,
A ceramic heater, wherein a narrow portion having a width smaller than that of the longitudinal portion is provided in at least a part of the plurality of connecting portions.   The ceramic heater according to claim 1, wherein the narrow portion is provided in the connecting portion that connects one end sides of the longitudinal portion.   The ceramic heater according to claim 1 or 2, wherein a ratio of a width of the narrow portion and a width of the longitudinal portion is in a range of 1: 1.2 to 1: 3.   The said narrow part is comprised so that thickness may become equal to the thickness of the said longitudinal part, and the width | variety is comprised so that it may become smaller than the width | variety of the said longitudinal part. Ceramic heater.   The ceramic heater according to any one of claims 1 to 4, wherein the plurality of longitudinal portions are arranged in parallel around an axis of the main body portion. 2. At least one of an end portion on one end side and an end portion on the other end side of the plurality of longitudinal portions is arranged such that positions in the axial direction of the main body portion are aligned in the circumferential direction of the main body portion. The ceramic heater as described in any one of -5.