WO2018199094A1

WO2018199094A1 - Heater

Info

Publication number: WO2018199094A1
Application number: PCT/JP2018/016616
Authority: WO
Inventors: 浜田　修
Original assignee: 京セラ株式会社
Priority date: 2017-04-26
Filing date: 2018-04-24
Publication date: 2018-11-01
Also published as: EP3618566A4; KR102207442B1; JPWO2018199094A1; KR20190124764A; EP3618566B1; CN110521279A; JP6510739B2; EP3618566A1; CN110521279B

Abstract

A heater of the present disclosure includes: a rod-shaped or cylindrical ceramic body (1) that has a slit-shaped recess (11) in the outer peripheral surface thereof extending from the leading end toward the back end; and a heating resistor (2) embedded inside the ceramic body (1). The heating resistor (2) includes a first resistor (21) and a second resistor (22) disposed in parallel. In addition, the heating resistor (2) has, between the leading end and rear end of the ceramic body (1), a first region (31) where the first resistor (21) and second resistor (22) repeatedly fold back and reciprocate in parallel along the circumferential direction, and a second region (32) that is adjacent to the slit-shaped recess (11) and where only the first resistor (21) reciprocates.

Description

heater

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

Conventionally, a ceramic body having a rod-like or cylindrical shape and having a slit-like recess extending on the outer peripheral surface from the front end toward the rear end, and a heating resistor embedded in the ceramic body, There is known a heater having a configuration including a first resistor and a second resistor in which bodies are arranged in parallel.

JP 2013-134880 A JP 2012-0667468 A

A heater according to the present disclosure includes a ceramic body having a rod-like or cylindrical shape and having a slit-like recess extending on the outer peripheral surface from the front end toward the rear end, and a heating resistor embedded in the ceramic body. Prepare. This heating resistor includes a first resistor and a second resistor arranged in parallel. The heating resistor has 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. And a second region in which only the first resistor reciprocates, the region being close to the slit-shaped recess.

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. FIG. 3 is a cross-sectional view taken along line III-III shown in FIG. It is an expanded view which shows the pattern of the heating 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 no heating resistor is disposed in the slit-like recess of the ceramic body. For this reason, when the temperature is raised, the temperature in the vicinity of the slit-shaped recess becomes lower than the temperature at the surrounding portion, and a temperature gradient is generated. And there was a problem in durability, such as a crack further progressing and there is a possibility that the heating resistor may be disconnected from the vicinity of the slit-like recess.

In recent years, there is a demand for a heater with a higher heating rate, and it is necessary to further improve the durability of the heater.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a heater excellent in durability in which disconnection of a heating resistor is suppressed.

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 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 is a rod-shaped or tubular-shaped ceramic body 1 having a slit-shaped recess 11 extending from the front end toward the rear end on the outer peripheral surface, and the interior of the ceramic body 1 And a heating resistor 2 embedded in the surface. The heating resistor 2 includes a first resistor 21 and a second resistor 22 arranged in parallel. Then, the heating resistor 2 has a first region 31 in which the first resistor 21 and the second resistor 22 are repeatedly folded back and forth in parallel along the circumferential direction between the front end and the rear end of the ceramic body 1. Have. Furthermore, it has the 2nd area | region 32 which is an area | region which adjoins the slit-shaped recessed part 11, and only the 1st resistor 21 reciprocates.

The ceramic body 1 is a rod-shaped or cylindrical member having a longitudinal direction. Examples of the rod shape include a columnar shape or a prismatic shape. In addition, the rod shape here includes, for example, a plate shape elongated in a specific direction. In addition, examples of the cylindrical shape include a cylindrical shape and a rectangular tube shape. In the heater of this example, the ceramic body 1 is cylindrical. The length of the ceramic body 1 is set to 20 to 60 mm, for example. When the ceramic body 1 has a cylindrical outer diameter or a circular cross section, the diameter is set to, for example, 2.5 to 5.5 mm.

When the ceramic body 1 has a cylindrical shape (cylindrical shape), the heater is used so as to heat an object to be heated in contact with the inner or outer peripheral surface of the ceramic body 1. Moreover, when the ceramic body 1 is rod-shaped, the heater is used so that an object to be heated is brought into contact with the outer peripheral surface of the ceramic body 1 and heated.

The ceramic body 1 is made of an insulating ceramic material. Examples of the insulating ceramic material include alumina, silicon nitride, and aluminum nitride. Alumina can be used in terms of oxidation resistance and easy manufacturing, silicon nitride in terms of excellent strength, toughness, high insulation and heat resistance, and aluminum nitride in terms of excellent thermal conductivity. The ceramic body 1 may contain a metal element compound 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-shaped or cylindrical core material 12 and a surface layer portion 13 provided so as to cover the side surface of the core material 12. The ceramic body 1 has a slit-like recess 11 extending from the front end toward the rear end on the outer peripheral surface. Here, the depth of the concave portion 11 (the thickness of the surface layer portion 13) is, for example, 0.1 to 1.5 mm. Further, the opening width of the recess 11 is, for example, 0.3 to 2 mm. Note that the opening width means the length of a curve along the outer diameter of the transverse cross section of the ceramic body 1 when the ceramic body 1 has a cylindrical cross section or a circular cross section.

A heating resistor 2 is embedded in the ceramic body 1. When the ceramic body is composed of the core material 12 and the surface layer portion 13, the heating resistor 2 is disposed between the core material 12 and the surface layer portion 13, for example.

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

Further, the heating resistor 2 is arranged so as to generate the most heat at the tip side of the ceramic body 1. In the example shown in FIGS. 1 to 4, the heating resistor 2 has a folded portion (meandering portion) provided along the circumferential direction while being repeatedly folded in the length direction on the tip side of the ceramic body 1. . The heating resistor 2 is a pair of linear portions on the rear end side of the folded portion, and is electrically connected to a later-described drawing portion at the rear end portion of each linear portion. The shape of the cross section of the heating resistor 2 may be any shape such as a circle, an ellipse, or a rectangle. The heating resistor 2 may be a pattern that repeatedly reciprocates between the front end side and the rear end side, instead of a pattern in which the folded portion that is repeatedly folded back is only on the front end side. A detailed pattern of the heating resistor 2 will be described later.

The heating resistor 2 may be formed using the same material for the folded portion on the front end side and the pair of linear portions on the rear end side. Further, in order to suppress unnecessary heat generation, by making the cross-sectional area of the linear portion larger than the cross-sectional area of the folded portion, or by reducing the content of the material of the ceramic body 1 included in the linear portion, The resistance value per unit length of the linear portion may be smaller than that of the folded portion.

The drawer part is embedded in the rear end side of the ceramic body 1. The lead portion is made of, for example, a through-hole conductor, and one end is electrically connected to the rear end portion of the heating resistor 2 and the other end is drawn to the side surface on the rear end side of the ceramic body 2. The lead-out part may be made of the same material as that of the heating resistor 2 or may be made of a material having a resistance value lower than that of the heating resistor 2. In FIG. 4, the drawing 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 portion embedded in the ceramic body 1. A lead terminal is bonded to the electrode pad 5 and is electrically connected to an external circuit (external power source). In the example shown in FIGS. 1 to 4, there are three portions from which the lead portion is drawn, and the electrode pad 5 is provided in each portion. Here, among the three electrode pads 5 in FIG. 4, the first pad as the common pad is connected to one end of both the first resistor 21 and the second resistor 22 via the lead portion. The pad 51 is connected to the other end of the first resistor 21 via the lead portion, and is connected to the second pad 52 and the other end of the second resistor 22 via the lead portion. This is the third pad 53.

The electrode pad 5 may be composed of only a conductor layer made of, for example, molybdenum (Mo) or tungsten (W), and may be one in which a plating layer made of, for example, Ni—B or Au is provided on the surface of the conductor layer. The electrode pad 5 has a thickness of 50 to 300 μm, for example, and a length and width of 5 to 10 mm, for example.

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

Further, the heating resistor 2 includes a first region 31 in which the first resistor 21 and the second resistor 22 are repeatedly folded back and forth in parallel along the circumferential direction between the front end and the rear end of the ceramic body 1. And a second region 32 that is close to the slit-like recess 11 and that only the first resistor 21 reciprocates.

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 along the first resistor 21. Are arranged in parallel on the rear end side, and are repeatedly folded back and forth along the circumferential direction between the front end and the rear end of the ceramic body 1. Further, as the pattern of the heating resistor 2 in the second region 32, only the first resistor 21 reciprocates, and together with the first resistor 21 in the first region 31, the slit-shaped recess 11. Thus, the three first resistors 21 are arranged close to both sides.

In the conventional structure in which only the first resistor 21 does not reciprocate in the region close to the slit-shaped recess 11, even if the first resistor 21 is heated first when the temperature rises, Since the first resistor 21 reciprocates in a region away from the region close to the slit-shaped recess 11, the temperature in the vicinity of the slit-shaped recess 11 is low, and the region in the region away from the vicinity of the slit-shaped recess 11 is low. As the temperature increased, it was difficult to make the temperature distribution on the outer peripheral surface of the heater uniform.

On the other hand, according to the heater of the present disclosure, the first resistor 21 is first heated when the temperature is raised, so that only the first resistor 21 reciprocates and the slit-shaped recess 11. The temperature in the vicinity increases. Therefore, the temperature distribution on the outer peripheral surface of the heater at the time of temperature rise is made uniform, thermal stress is relaxed, and durability is improved.

Further, according to this configuration, as shown in FIG. 4, the folded portion in the first resistor 21 and the folded in the second resistor 22 where the current supplied from the first pad 51 as the common pad first arrives. Since the distance to the part is increased, the thermal stress applied to each folded part can be dispersed, so that 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 becomes large, so the amount of heat generated increases. Therefore, the rate of temperature increase near the slit-shaped recess 11 is increased, the temperature distribution on the outer peripheral surface of the heater is made uniform, and the thermal stress is relaxed, so that 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 the second resistor. It is possible to make the configuration 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 determining whether or not such a configuration is used, if the line width of the first resistor 21 is not constant over the whole and the line width of the second resistor 22 is constant over the whole, The line width of the thinnest (narrow) portion of the first resistor 21 is compared with the line width of the second resistor 22. In addition, when the line width of the second resistor 22 is not constant over the whole and the line width of the first resistor 21 is constant over the whole, the line of the thickest (widest) portion of the second resistor 22 is provided. The width and the line width of the first resistor 21 are compared. Further, when the line widths of the first resistor 21 and the second resistor 22 are not constant throughout, the line width of the narrowest part of the first resistor 21 and the second resistance Contrast with the line width of the thickest (widest) part of the body 22.

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 can be used as the first resistor 21, and a material such as a tungsten-rhenium alloy can be used as the second resistor 22. Further, the same conductor material is used, and even if a larger amount of the same insulating material as that of the ceramic body 1 is added to the second resistor 22 than to the first resistor 21, the first resistor is more than the second resistor 22. The specific resistance of 21 can be reduced.

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

Whether or not it has such a configuration includes, for example, a part farthest from the slit-like recess 11 (a central part in FIG. 6), a part 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 the portion adjacent to the concave portion 11. At this time, each part means the part in the circumferential direction of the ceramic body 1, and when the position of the circumferential part is the same and the line width changes along the length direction, The line width at the tip in the vertical direction, the line width at the center, and the line width at the rear end are measured and averaged to determine the line width of the part in the circumferential direction.

In FIG. 6, the line width of the second resistor 22 is substantially constant over the whole, and the first resistor 21 located on the side close to the slit-shaped recess 11 in the second region 32. The line width is narrower than the line width of the first resistor 21 located on the side far from the slit-like recess 11. Even the line width of the thinnest portion of the first resistor 21 is thicker (wider) than the line width of the second resistor 22. Thereby, the amount of heat generated in the vicinity of the slit-like recess 11 can be further increased.

However, the form in which the line width becomes narrower (narrow) gradually or stepwise as the first resistor 21 approaches the slit-like recess 11 is not limited to the form shown in FIG. This 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 thinner (narrower) than the line width of the second resistor 22 throughout. Further, the portion of the first resistor 21 farthest from the slit-like recess 11 (the central portion in FIG. 6) has a thicker (wider) line width than the second resistor 22, and the first resistance A configuration may be employed in which the line width is narrower (narrower) than that of the second resistor 22 in a portion (a portion where the line width is the narrowest) in the body 21 that is close to the slit-like recess 11.

Further, as shown in FIG. 7, in the first resistor 21, the distance between the patterns may be gradually or gradually reduced as the slit 21 approaches the slit-like recess 11. When the interval between patterns becomes narrow, the first resistors 21 are densely arranged, and the amount of heat generated in this region increases. Even in this configuration, the temperature in the vicinity of the second region 31 where only the first resistor 21 reciprocates and the slit-like recess 11 is increased, the temperature distribution on the outer peripheral surface of the heater is made uniform, and the thermal stress is alleviated. And durability is improved.

Next, an example of a heater manufacturing method 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 ceramic mainly composed of Al ₂ O ₃ , the ceramic body 1 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 shape to produce a ceramic green sheet that becomes the surface layer portion 13 of the ceramic body 1.

A resistor paste pattern to be the heating resistor 2 is formed on one main surface of the ceramic green sheet using a technique such as screen printing. Further, a conductive paste to be the electrode pad 5 is formed in a predetermined pattern shape on the surface of the ceramic green sheet opposite to the surface on which the heat generating resistor 2 is formed in the same manner as the heat generating resistor 2 is formed. Moreover, the ceramic green sheet is filled with a conductor paste for forming a through-hole conductor as a lead portion and a hole for electrically connecting the heating resistor 2 and the electrode pad 5.

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

Resistor paste and conductor paste can be prepared by mixing and kneading a ceramic raw material, a binder, an organic solvent, etc. with a high melting point metal such as W, Mo, Re, etc., which can be prepared by simultaneous firing with a ceramic body. At this time, the heating position of the heating resistor 2 can be changed by changing the length of the resistor paste or conductive paste pattern, the distance / interval of the folded pattern, and the line width of the pattern depending on the application of the heater. And the resistance value can be set to a desired value.

On the other hand, a columnar 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 having the same composition is dispersed is applied to the core material 12, and the alumina ceramic green sheet to be the surface layer portion 13 is wound and brought into close contact, whereby the ceramic body 1 is obtained. An alumina-based integral molded body can be obtained.

In addition, in order to provide the slit-shaped recessed part 11 (groove part) extended in a longitudinal direction in the outer peripheral surface (side surface) of the ceramic body 1, the edge and end of the alumina ceramic green sheet (surface layer part 13) wound around the core material 12 are provided. A gap may be provided between the two.

The alumina-based integrally molded body thus obtained is fired at, for example, 1500 to 1600 ° C. in a non-oxidizing gas atmosphere such as hydrogen gas or a mixed gas of nitrogen gas and hydrogen gas (forming gas), and the outer periphery of the ceramic body 1 An Ni-plated film is provided on the electrode pad 5 on the surface, for example, by electrolytic plating to produce an alumina-based sintered body.

Further, a lead terminal made of, for example, Ni as a power feeding portion is joined to the electrode pad 5 using Ag brazing, solder or the like as the brazing material. The lead terminal coated with an insulating material in advance may be removed from the insulating material only at a portion necessary for bonding, and the removed portion may be connected to the electrode pad 5. Further, 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 is obtained by the above method.

1: Ceramic body 11: Slit-shaped recess 12: Core material 13: Surface layer part 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

A ceramic body having a rod-like or cylindrical shape and having a slit-like recess extending from the front end toward the rear end on the outer peripheral surface, and a heating resistor embedded in the ceramic body,
The heating resistor includes a first resistor and a second resistor arranged in parallel, and the first resistor and the first resistor along the circumferential direction between the front end and the rear end of the ceramic body. The second resistor has a first region that repeatedly folds back and forth in parallel, and a second region that is close to the slit-shaped recess and only the first resistor reciprocates. Has 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 thicker than a line width of the second resistor.
The heater according to claim 1 or 2, wherein a specific resistance of the first resistor is smaller than a specific resistance of the second resistor.
The heater according to any one of claims 1 to 4, wherein the first resistor has a line width that gradually or gradually decreases as the slit-shaped recess is approached.
The heater according to any one of claims 1 to 5, wherein an interval between the patterns of the first resistor gradually becomes narrower or gradually as it approaches the slit-like recess.