JPWO2018199094A1 - heater - Google Patents

Abstract

The heater according to the present disclosure is a rod-like or tubular ceramic body (1) having a slit-like recess (11) extending from the front end to the rear end on the outer peripheral surface, and the ceramic body (1) And an embedded heating resistor (2). The heating resistor (2) includes a first resistor (21) and a second resistor (22) arranged in parallel. In the heat generating resistor (2), the first resistor (21) and the second resistor (22) are repeatedly bent in parallel along the circumferential direction between the front end and the rear end of the ceramic body (1) And has a second area (32) in which only the first resistor (21) reciprocates, which is an area close to the slit-like recess (11). doing.

Description

  The present disclosure relates to a heater used for fluid heating, powder heating, gas heating, an oxygen sensor, a solder iron and the like.

  Conventionally, a ceramic body having a rod-like or cylindrical shape and a slit-like concave portion extending from the front end to the rear end on the outer peripheral surface, and a heating resistor embedded inside the ceramic body, A heater is known which is configured to include a first resistor and a second resistor in which the bodies are arranged in parallel.

JP 2013-134880 A JP, 2012-067468, A

  The heater according to the present disclosure is a rod-like or cylindrical ceramic body having a slit-like concave portion extending from the front end to the rear end on the outer peripheral surface, and a heating resistor embedded inside the ceramic body. Prepare. The heat generating resistor includes a first resistor and a second resistor arranged in parallel. In addition, the heat generating resistor may be a first region in which the first resistor and the second resistor are repeatedly folded back and forth in parallel along the circumferential direction between the front end and the rear end of the ceramic body. While having it, it is an area | region which is adjacent to the said slit-shaped recessed part, and has a 2nd area | region where only the said 1st resistor reciprocates.

It is a schematic perspective view which shows an example of a heater. It is a partially broken perspective view of the heater shown in FIG. It is sectional drawing cut | disconnected by the III-III line shown in FIG. It is an expanded view which shows the pattern of the heat-generating resistor shown in FIG. It is an expanded view which shows the pattern of the heating resistor of the other example of a heater. It is an expanded view which shows the pattern of the heating resistor of the other example of a heater. It is an expanded view which shows the pattern of the heating resistor of the other example of a heater.

  The conventional heater has a configuration in which the heating resistor is not disposed in the slit-like recess of the ceramic body. Therefore, when the temperature rises, the temperature in the vicinity of the slit-like concave portion becomes lower than the temperature of the surrounding portion, and a temperature gradient is generated, and when a thermal cycle is applied, there is a possibility that microcracks may occur in the ceramic body due to thermal stress. Then, there is a problem in the durability that, for example, the crack may further develop and the heat generating resistor may be broken starting from the vicinity of the slit-like concave portion.

  Further, in recent years, a heater having a higher temperature rise rate is required, and it is necessary to further improve the durability of the heater.

  This indication is made in view of the above-mentioned situation, and an object of the present indication is to provide a heater which was able to control a disconnection of a heating resistor and was excellent in endurance.

  Hereinafter, an example of the heater of the present embodiment will be described with reference to the drawings.

  FIG. 1 is a schematic perspective view showing an example of a heater, and FIG. 2 is a partially broken perspective view of the heater shown in FIG. 3 is a cross-sectional view taken along the line III-III shown in FIG. FIG. 4 is a development view showing a pattern of the heating resistor shown in FIG.

  The heater of the present disclosure shown in FIGS. 1 to 4 has a rod-like or cylindrical shape, and a ceramic body 1 having a slit-like recess 11 extending from the front end to the rear end on the outer peripheral surface; And the heating resistor 2 embedded in the The heating resistor 2 also includes a first resistor 21 and a second resistor 22 arranged in parallel. Then, the heating resistor 2 is in the first region 31 in which the first resistor 21 and the second resistor 22 repeatedly return in parallel and reciprocate in the circumferential direction between the front end and the rear end of the ceramic body 1. Have. Furthermore, it has a second region 32 which is a region close to the slit-like concave portion 11 and in which only the first resistor 21 reciprocates.

  The ceramic body 1 is a rod-like or cylindrical member having a longitudinal direction. As rod shape, cylindrical shape or prismatic shape etc. are mentioned, for example. Here, the rod-like shape includes, for example, a plate-like shape elongated in a specific direction. Moreover, as cylindrical shape, cylindrical shape or square cylinder shape is mentioned, for example. In the heater of this example, the ceramic body 1 is cylindrical. The length of the ceramic body 1 is set to, for example, 20 to 60 mm. The diameter in the case where the ceramic body 1 has a cross-sectional cylindrical outer diameter or a cross-sectional circular shape is set to, for example, 2.5 to 5.5 mm.

  When the ceramic body 1 is cylindrical (cylindrical), the heater is used to bring the object to be heated into contact with the inner peripheral surface or the outer peripheral surface of the ceramic body 1 for heating. When the ceramic body 1 is in the shape of a rod, the heater is used so as to bring the object to be heated into contact with the outer peripheral surface of the ceramic body 1 to heat it.

The ceramic body 1 is made of an insulating ceramic material. Examples of the insulating ceramic material include alumina, silicon nitride and aluminum nitride. It is possible to use alumina, which is oxidation resistant and easy to manufacture, silicon nitride from the viewpoint of high strength, high toughness, high insulation, and excellent heat resistance, and aluminum nitride from the viewpoint of excellent thermal conductivity. The ceramic body 1 may contain a compound of a metal element contained in the heating resistor 2. For example, when the heating resistor 2 contains tungsten or molybdenum, the ceramic body 1 may contain WSi ₂ or MoSi ₂ may be included.

  Further, the ceramic body 1 has, for example, a rod-like or cylindrical core material 12 and a surface layer part 13 provided so as to cover the side surface of the core material 12. The ceramic body 1 also has a slit-like recess 11 extending from the front end to the rear end on the outer peripheral surface. Here, the depth of the recess 11 (the thickness of the surface layer portion 13) is, for example, 0.1 to 1.5 mm. Moreover, the opening width of the recessed part 11 shall be 0.3-2 mm, for example. The opening width means the length of a curve along the outer diameter in the cross section of the ceramic body 1 when the ceramic body 1 has a cylindrical shape or a circular shape in cross section.

  The heating resistor 2 is embedded in the ceramic body 1. In the case where the ceramic body includes the core 12 and the surface layer 13, the heating resistor 2 is disposed, for example, between the core 12 and the surface layer 13.

  The heating resistor 2 generates heat when a current flows and heats the ceramic body 1. The heating resistor 2 is made of, for example, a conductor whose main component is a high melting point metal such as tungsten (W), molybdenum (Mo) or rhenium (Re). The dimensions of the heat generating resistor 2 are, for example, 0.3 to 2 mm in width and 0.01 to 0.1 mm in thickness, and the total length including the lengths of all the heat generating resistors 2 is set to 500 to 5000 mm. be able to. These dimensions are appropriately set depending on the heat generation temperature of the heat generating resistor 2, the voltage applied to the heat generating resistor 2, and the like.

  Further, the heating resistor 2 is disposed so as to generate the most heat on the tip end side of the ceramic body 1. In the example shown in FIGS. 1 to 4, the heating resistor 2 has a folded portion (serpentine portion) provided along the circumferential direction while being repeatedly folded back in the length direction on the tip side of the ceramic body 1 . Further, the heat generating resistor 2 is a pair of linear portions on the rear end side of the folded portion, and is electrically connected to a lead-out portion described later at the rear end portions of the respective linear portions. The shape of the cross section of the heat generating resistor 2 may be any shape such as a circle, an ellipse, or a rectangle. The heating resistor 2 may not be a pattern in which the folded back portion is repeatedly folded only on the front end side, but may be a pattern in which the back end side repeatedly reciprocates between the front end side and the rear end side. The detailed pattern of the heating resistor 2 will be described later.

  The heating resistor 2 may be formed by using the same material as the folded-back portion on the front end side and the pair of linear portions on the rear end side. Moreover, in order to suppress unnecessary heat generation, the cross-sectional area of the linear part is made larger than the cross-sectional area of the folded part, or the content of the material of the ceramic body 1 contained in the linear part is reduced. The resistance per unit length of the linear portion may be smaller than that of the folded portion.

  At the rear end side of the ceramic body 1, a lead-out portion is embedded. The lead-out portion is made of, for example, a through hole conductor, and one end thereof is electrically connected to the rear end portion of the heat generating resistor 2 and the other end is drawn to the side surface on the rear end side of the ceramic body 2. The lead portion may be made of the same material as the heat generating resistor 2 or may be made of a material having a lower resistance value than the heat generating resistor 2. In FIG. 4, the lead-out portion is omitted.

  An electrode pad 5 is provided on the side surface on the rear end side of the ceramic body 1 as necessary, and is electrically connected to a lead-out portion embedded in the ceramic body 1. Then, a lead terminal is bonded to the electrode pad 5 and electrically connected to an external circuit (external power supply). In the example shown in FIGS. 1 to 4, there are three parts from which the lead-out part is pulled out, and the electrode pad 5 is provided at each part. Here, among the three electrode pads 5 in FIG. 4, it is a first common pad that is connected to one end of both the first resistor 21 and the second resistor 22 through the lead-out portion. The pad 51 is connected to the other end of the first resistor 21 via the lead-out portion is connected to the other end of the second pad 52 and the other end of the second resistor 22 via the lead-out portion Is the third pad 53.

  The electrode pad 5 may be formed only of a conductor layer made of, for example, molybdenum (Mo) or tungsten (W), or may be provided with a plated layer made of, for example, Ni-B or Au on the surface of the conductor layer. The electrode pad 5 has a thickness of, for example, 50 to 300 μm, and a length and a width of, for example, 5 to 10 mm.

  Then, as shown in FIG. 4, the heating resistor 2 includes a first resistor 21 and a second resistor 22 arranged in parallel. One heating resistor (for example, the first resistor 21) when the operating temperature is low because the heating resistor 2 includes the first resistor 21 and the second resistor 22 arranged in parallel. When applying a voltage only to reduce the amount of heat generation or using at a higher temperature, the amount of heat generation can be obtained by simultaneously applying a voltage to a plurality of heating resistors (the first resistor 21 and the second resistor 22) Can be raised. That is, the calorific value can be easily adjusted.

  Furthermore, the heating resistor 2 is a first region 31 in which the first resistor 21 and the second resistor 22 repeatedly return in parallel and reciprocate in the circumferential direction between the front end and the rear end of the ceramic body 1. And a second region 32 in which only the first resistor 21 reciprocates, which is a region close to the slit-like recess 11.

  At this time, as a pattern of the heating resistor 2 in the first region 31, the first resistor 21 is disposed on the tip side of the ceramic body 1, and the second resistor 22 is arranged along the first resistor 21. It is disposed parallel to the rear end side, and is repeatedly folded back and forth along the circumferential direction between the front end and the rear end of the ceramic body 1. In addition, as a pattern of the heating resistor 2 in the second region 32, only the first resistor 21 reciprocates, and in combination with the first resistor 21 in the first region 31, a slit-shaped concave portion 11 The three first resistors 21 are disposed in proximity to each of the two sides.

  In the conventional structure in which only the first resistor 21 reciprocates in the region close to the slit-like recess 11, even if the first resistor 21 is heated first at the time of temperature rise, Since the first resistor 21 reciprocates in the area away from the area close to the slit-like recess 11, the temperature in the vicinity of the slit-like recess 11 is low, and the area away from the vicinity of the slit-like recess 11 As the temperature rose, the temperature distribution on the outer peripheral surface of the heater was not uniform.

  On the other hand, according to the heater of the present disclosure, by heating the first resistor 21 first at the time of temperature rise, the second region 31 in which only the first resistor 21 reciprocates and the slit-shaped concave portion 11 The temperature in the vicinity becomes high. Therefore, the temperature distribution on the outer peripheral surface of the heater at the time of temperature rise is made uniform, the thermal stress is alleviated, and the durability is improved.

  Further, according to this configuration, as shown in FIG. 4, the folded portion in the first resistor 21 and the folded portion in the second resistor 22 to which the current supplied from the first pad 51 as the common pad first reaches Since the distance from the part is long, the thermal stress applied to each of the folded parts can be dispersed, and the durability of the heater is improved.

  Here, the resistance value of the first resistor 21 may be smaller than the resistance value of the second resistor 22. If the resistance value is small, the current increases, and the amount of heat generated increases. Therefore, the temperature rising speed in the vicinity of the slit-like concave portion 11 is increased, the temperature distribution on the outer peripheral surface of the heater is made uniform, and the thermal stress is relieved, whereby the durability is improved.

  As a method of making the resistance value of the first resistor 21 smaller than the resistance value of the second resistor 22, for example, as shown in FIG. 5, the line width of the first resistor 21 is a second resistor. It can be made thicker (wider) than the line width of 22. At this time, the line width of the second resistor 22 is, for example, 1.1 to 1.5 times the line width of the first resistor 21. When it is determined whether or not such a configuration is adopted, the line width of the first resistor 21 is not constant throughout, and the line width of the second resistor 22 is constant throughout: The line width of the narrowest portion of the first resistor 21 and the line width of the second resistor 22 are compared. Further, when the line width of the second resistor 22 is not constant throughout, and the line width of the first resistor 21 is constant throughout, the line of the thickest (wide) portion of the second resistor 22 The width and the line width of the first resistor 21 are compared. If the line widths of the first resistor 21 and the second resistor 22 are not constant throughout, the line width of the narrowest (narrowed) portion of the first resistor 21 and the second resistance Contrast with the line width of the thickest (widest) part of the body 22.

  Further, as a method of making the resistance value of the first resistor 21 smaller than the resistance value of the second resistor 22, the specific resistance of the first resistor 21 is smaller than the specific resistance of the second resistor 22. It can also be configured. At this time, the specific resistance of the first resistor 21 is, for example, 20 to 80% of that of the second resistor 22. In order to achieve such a relationship, for example, a material such as a tungsten-molybdenum alloy may be used as the first resistor 21, and a material such as a tungsten-rhenium alloy may be used as the second resistor 22. Also, even if the same conductor material is used and the same insulating material as the ceramic body 1 is added to the second resistor 22 more than the first resistor 21, the first resistor is more than the second resistor 22. The specific resistance of 21 can be reduced.

  Further, as shown in FIG. 6, the line width of the first resistor 21 may be narrowed (narrowed) gradually or stepwise as it approaches the slit-like recess 11. If there is a portion where the line width is narrow (a portion where the cross-sectional area is small) in the first resistor 21, the amount of heat generated in the portion where the line width is smaller than the other portions is growing. As a result, the temperature in the vicinity of the second region 31 and the slit-like concave portion 11 in which only the first resistor 21 reciprocates is increased, the temperature distribution on the outer peripheral surface of the heater is uniformed, and the thermal stress is relaxed. Improves the quality.

  For example, whether it has such a configuration is a portion farthest from the slit-like concave portion 11 (the central portion in FIG. 6), a portion located at the boundary between the first region 31 and the second region 32, and a slit It can be determined by comparing the line width of the first resistor 21 with a portion close to the concave portion 11 in the shape of a circle. At this time, each portion means a portion in the circumferential direction of the ceramic body 1, and if the positions of the portions in the circumferential direction are the same and the line width changes along the length direction, the length is long. It is determined that the line width at the tip end in the longitudinal direction, the line width at the center, and the line width at the rear end are measured and averaged to be the line width of the portion in the circumferential direction.

  In FIG. 6, the line width of the second resistor 22 is substantially constant throughout, and in the second region 32, the first resistor 21 located on the side close to the slit-like recess 11 is The line width is smaller than the line width of the first resistor 21 located far from the slit-like recess 11. Further, even the line width of the narrowest portion of the first resistor 21 is wider (wider) than the line width of the second resistor 22. Thereby, the amount of heat generated in the vicinity of the slit-like concave portion 11 can be further increased.

  However, the form in which the line width is gradually or stepwise narrowed (narrowed) as the first resistor 21 approaches the slit-like recess 11 is not limited to the form shown in FIG. It may be applied when the line width of the body 21 is narrower (narrower) than the line width of the second resistor 22. At this time, the line width of the first resistor 21 may be narrower (narrower) than the line width of the second resistor 22 throughout. Further, the portion (center portion in FIG. 6) farthest from the slit-like recess 11 in the first resistor 21 has a wider (wider) line width than the second resistor 22, and thus the first resistance The line width may be narrower (narrower) than that of the second resistor 22 at a portion close to the slit-like concave portion 11 in the body 21 (the portion where the line width becomes the narrowest).

  Further, as shown in FIG. 7, the distance between the patterns may be narrowed gradually or stepwise as the first resistor 21 approaches the slit-like recess 11. When the spacing between the patterns becomes narrow, the first resistors 21 are densely arranged, and the amount of heat generated in this region becomes large. Also in this configuration, the temperature in the vicinity of the second region 31 and the slit-like concave portion 11 in which only the first resistor 21 reciprocates increases, so that the temperature distribution on the outer peripheral surface of the heater becomes uniform and the thermal stress is relaxed. Durability is improved.

  Next, an example of a method of manufacturing the heater will be described. In this example, the case where the ceramic body is made of alumina ceramic will be described.

First, in order to produce the ceramic body 1 made of an alumina-based ceramic containing Al ₂ O ₃ as a main component, it was prepared by adding a sintering aid such as SiO ₂ , CaO, MgO, ZrO ₂ to Al ₂ O ₃ . The ceramic slurry is formed into a sheet, and a ceramic green sheet to be the surface layer portion 13 of the ceramic body 1 is produced.

  A pattern of a resistor paste to be the heat generating resistor 2 is formed on one main surface of the ceramic green sheet using a method such as screen printing. Further, on the surface of the ceramic green sheet opposite to the surface on which the heating resistor 2 is to be formed, a conductor paste to be the electrode pad 5 is formed in a predetermined pattern as in the case of the heating resistor 2. Further, the ceramic green sheet is subjected to hole processing for electrically connecting the heat generating resistor 2 and the electrode pad 5 and filling with a conductor paste for forming a through hole conductor as a lead-out portion.

  Here, the pattern of the heating resistor 2 is, for example, as shown in FIG. 4, arranged in parallel with the patterns of a plurality of resistors (including the first resistor 21 and the second resistor) from the common pad 51, The first region 31 that repeatedly reciprocates up and down is provided, and the second region 32 is formed so as to reciprocate only the pattern of the outermost resistor (first resistor 21) up and down.

  The resistor paste and the conductor paste can be prepared by mixing and kneading a ceramic raw material, a binder, an organic solvent and the like with a high melting point metal such as W, Mo, Re which can be prepared by co-firing with a ceramic body. At this time, the heat generation position of the heat generating resistor 2 is changed by changing the length of the pattern of the resistor paste or conductive paste serving as the resistor, the distance / interval of the folded pattern, and the line width of the pattern according to the application of the heater. The resistance value can be set to a desired value.

  On the other hand, a cylindrical or cylindrical alumina ceramic molded body to be the core material 12 is molded by extrusion molding.

  Then, an adhesive liquid in which alumina ceramics of the same composition are dispersed is applied to the core material 12, and the alumina ceramic green sheet to be the surface layer portion 13 described above is wound and adhered to form the ceramic body 1. An alumina integrated molding can be obtained.

  In order to provide slit-like recessed portions 11 (grooves) extending in the longitudinal direction on the outer peripheral surface (side surface) of the ceramic body 1, the ends and ends of the alumina ceramic green sheet (surface layer 13) wound around the core 12 A gap may be provided between the

  The outer periphery of the ceramic body 1 is fired, for example, at 1500 to 1600 ° C. in an atmosphere of non-oxidizing gas such as hydrogen gas or mixed gas of nitrogen gas and hydrogen gas (forming gas), etc. A Ni plating film is provided on the surface of the electrode pad 5 by electrolytic plating, for example, to prepare an alumina integrated sintered body.

  Further, a lead terminal made of, for example, Ni as a feeding portion is joined to the electrode pad 5 by using Ag solder, solder or the like as a brazing material. The lead terminal may be pre-coated with an insulating material, and the insulating material may be removed only at a portion necessary for bonding, and the removed portion may be connected to the electrode pad 5. In addition, after connecting the Ni wire to the electrode pad 5, an insulating tube may be provided on the Ni wire.

  The heater of this embodiment can be obtained by the above method.

1: Ceramic body 11: Slit-shaped concave portion 12: Core material 13: Surface layer portion 2: Heating resistor 21: first resistor 22: second resistor 31: first region 32: second region 5 : Electrode pad 51: first pad 52: second pad 53: third pad

Claims (6)

A ceramic body having a rod-like or cylindrical shape and having a slit-like concave portion extending from the front end to the rear end on the outer peripheral surface, and a heating resistor embedded inside the ceramic body,
The heat-generating resistor includes a first resistor and a second resistor arranged in parallel, and the first resistor and the first resistor along a circumferential direction between the front end and the rear end of the ceramic body The second resistor has a first region in which the second resistor repeatedly and repeatedly returns in parallel and reciprocates, and is a region close to the slit-like concave portion and in which only the first resistor reciprocates Have a heater.   The heater according to claim 1, wherein a resistance value of the first resistor is smaller than a resistance value of the second resistor.   The heater according to claim 1 or 2, wherein a line width of the first resistor is wider than a line width of the second resistor.   The heater according to claim 1 or 2, wherein a resistivity of the first resistor is smaller than a resistivity of the second resistor.   The heater according to any one of claims 1 to 4, wherein the line width of the first resistor gradually or gradually decreases as it approaches the slit-like recess.   The heater according to any one of claims 1 to 5, wherein the distance between the patterns becomes narrower gradually or in stages as the first resistor approaches the slit-like recess.

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