JP2008108801A - Method of manufacturing thermistor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a thermistor element that can easily adjust resistance value between a pair of electrode wires projecting the outside of a main unit. <P>SOLUTION: An adjusting hole 20 is made between a pair of electrode wires 30 and 40 that are varied in the main unit 10 of the thermistor element 1. A die for manufacturing the thermistor element 1 is possible to adjust the quantity of an adjusting hole formation pin for forming the adjusting hole 20 that is inserted into an inner space. Thus, a resistance value between the electrode wires 30 and 40 becomes possible to be adjusted according to a depth of the formed adjusting hole 20, so that, even if a material for the thermistor is changed, the same die is used to obtain the thermistor element having a target resistance value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a thermistor element suitable as an element for detecting the temperature of a measurement object such as a gas such as exhaust gas or a liquid.

  Conventionally, various sensors are attached to detect the state of exhaust gas discharged from an automobile engine, and a temperature sensor for measuring the temperature of exhaust gas is known as one of these sensors. A thermistor element is used as a temperature detecting element constituting the temperature sensor. The thermistor element has a configuration in which a pair of electrode wires protrudes in parallel with each other from a body portion for detecting temperature, and is generally formed by press molding using a mold. In the press molding, for example, the electrode wires are inserted into a pair of insertion holes that extend through the side wall of the split mold and extend toward the internal space formed when the mold is assembled. The thermistor material is introduced and one end of the electrode wire is embedded in the thermistor material. Then, the thermistor material is formed by pressing the thermistor material with a press device, taking out the formed thermistor body from the mold and firing it (see, for example, Patent Document 1).

In such a thermistor element, the resistance value of the thermistor material constituting the main body portion changes according to the temperature of the exhaust gas, but the resistance value between the electrode lines detected as the detection value of the thermistor element is the electrode in the main body portion. This is the resistance value of the thermistor material interposed between the lines.
JP 2004-56060 A

  However, when the thermistor material is changed due to the improvement of the thermistor element, if the thermistor element made of a new thermistor material is formed using the mold used so far, the distance between the pair of electrode lines does not change. Depending on the characteristics of the new thermistor material, the relationship between the resistance value between the electrode wires and the temperature may change. On the other hand, there is a case where the relationship between the temperature of the thermistor element and the resistance value is required to be changed due to the development of the temperature sensor. Therefore, in order to match the new thermistor material and to obtain the desired resistance value, redesigning the size of the main body and the distance between the electrode wires may require the creation of a new mold, or thermistor Since the design of the electric circuit of the temperature sensor needs to be changed according to the characteristics of the element, there is a problem that the cost of the thermistor element, the temperature sensor, or the temperature detection system is inevitably increased.

  The present invention has been made to solve the above-described problems, and provides a method for manufacturing a thermistor element capable of easily adjusting a resistance value between a pair of electrode wires protruding outside a main body. Objective.

  In order to achieve the above object, a thermistor element manufacturing method according to a first aspect of the present invention includes a main body portion made of a thermistor material, embedded in the main body portion, and at least one end projecting outside the main body portion. A method for manufacturing a thermistor element having a pair of electrode wires, wherein a part of the pair of electrode wires is spaced apart from each other in an internal space of a mold into which the thermistor material is to be introduced. The pair of electrode wires are arranged in the mold so as to be arranged, and a hollow part forming member capable of adjusting the amount of insertion of the mold into the internal space is part of the electrode wire. And placing the thermistor material into the internal space of the mold after the placing step, and placing the thermistor material in accordance with a predetermined insertion amount, Done, said A press step for forming a pair of electrode wires and a thermistor molded body in which a part of the hollow portion forming member is embedded, a drawing step for extracting the hollow portion forming member from the thermistor molded body, and a thermistor molded body after the extracting step Is fired to obtain the thermistor element.

  According to a second aspect of the present invention, there is provided a method for manufacturing a thermistor element, wherein, in addition to the configuration of the first aspect of the invention, the hollow portion forming member has a columnar shape and extends to the mold along the axial direction thereof. The amount of insertion is adjusted.

  According to a third aspect of the present invention, there is provided a thermistor element manufacturing method according to the first or second aspect of the invention, wherein when the pair of electrode wires are disposed in the mold, Of the inner wall surfaces constituting the inner space, the first inner wall surface including the portion from which the pair of electrode wires protrudes is formed in a planar shape orthogonal to the protruding direction of the pair of electrode wires. Features.

  According to a fourth aspect of the present invention, there is provided a thermistor element manufacturing method according to any one of the first to third aspects, wherein the pair of electrode wires is disposed in the mold. The other end of the pair of electrode wires opposite to the one end is exposed in the internal space, and the tip of the other end is a second that faces the first inner wall surface across the internal space. It is characterized by reaching the inner wall surface.

  According to a fifth aspect of the present invention, there is provided a thermistor element manufacturing method according to the fourth aspect of the present invention, wherein a part of the thermistor element is disposed between the pair of electrode wires in the inner space of the mold. An insertion port for inserting the hollow portion forming member into the internal space is provided in the second inner wall surface.

  In the method for manufacturing the thermistor element of the invention according to claim 1, a pair of electrode wires are arranged in the inner space of the mold, and further, a thermistor material is introduced and press-molded after a hollow portion forming member is arranged, Thereafter, the thermistor element is obtained by firing the press-molded body from which the hollow portion forming member has been removed. At this time, by forming the hollow portion formed by the hollow portion forming member between the pair of electrode wires, in the obtained thermistor element, the pair of electrode wires corresponding to the portion where the hollow portion is formed Between the parts, current flows around the hollow portion, and the resistance value between the pair of electrode wires can be increased. This hollow portion forming member can be adjusted in the amount of insertion into the inner space of the mold, and the proportion of the hollow portion between the pair of electrode wires of the thermistor element to be manufactured is adjusted by the amount of insertion. The resistance value between the electrode wires can be adjusted.

  The amount of insertion of the hollow portion forming member into the inner space of the mold is different depending on the material of the thermistor material that constitutes the main body portion, while maintaining a constant interval between the pair of electrode wires. Even when a plurality of types (product numbers) of thermistor elements are manufactured using the thermistor material, a thermistor element having a desired resistance value can be obtained efficiently. In other words, in order to obtain a plurality of types of thermistor elements using different thermistor materials, it is not necessary to prepare dies corresponding to the number of types, so that the manufacturing process can be simplified and the thermistor elements can be obtained at low cost. be able to.

  According to the invention according to claim 2, the hollow part formed by such a hollow part forming member has a columnar shape, so that no corners are formed on the inner surface and the mechanical strength can be increased. . Further, when the hollow part forming member is extracted from the thermistor molded body, if the hollow part forming member is cylindrical, it can be extracted while twisting about the axis, and damage to the main body part can be prevented.

  The hollow portion forming member may be inserted into the mold with its own axial direction orthogonal to the axial direction of the pair of electrode wires, but its own axial direction is aligned with the axial direction of the pair of electrode wires. In this state, it is preferable to adjust the amount of insertion into the mold. In this way, since the depth of the hollow portion formed by the hollow portion forming member is substantially proportional to the proportion of the hollow portion between the pair of electrode wires, the resistance value between the pair of electrode wires is adjusted. Can be performed with higher accuracy.

  Moreover, if the 1st inner wall surface of the metal mold | die containing the site | part from which a pair of electrode wire protruded is formed planar like the invention which concerns on Claim 3, the main-body part formed with the 1st inner wall surface The surface of the part can be planar. Usually, in order to remove the thermistor molded body from the mold, it is necessary to take out in the axial direction of the pair of electrode wires, and at the time of the removal, the first inner wall surface of the mold and the main body are orthogonal to the plane. Will be separated in the direction. That is, the first inner wall surface and the main body portion do not slide in a contact state, and friction does not occur. The vicinity of the base of the electrode wire protruding from the main body is a relatively low site in terms of strength, but friction does not occur at that site when the thermistor molded body is removed, so there is no gap between the electrode wire and the main body. Peeling is unlikely to occur and damage to the thermistor molded body can be effectively prevented.

  By the way, the thermistor molded object shape | molded by a metal mold | die becomes a form by which a main-body part is supported by a pair of electrode wire. Therefore, as in the invention according to claim 4, in the main body, the other end of the pair of electrode wires is opposed to the first inner wall surface from the surface of the portion of the main body formed by the first inner wall surface of the mold. If the second inner wall surface is formed so as to pass through the surface of the main body portion, the other end portion of the electrode wire can be disposed in the main body portion with a longer distance to support the main body portion. Therefore, the mechanical strength of the thermistor molded body can be increased. Further, when the pair of electrode wires is arranged in the mold, the case where the electrode wires are in contact with the second inner wall surface may be used as a reference for the insertion amount of the electrode wires into the internal space. Since the amount of insertion in the main body can be easily equalized, variation in resistance value between the two electrode lines for each product can be suppressed.

  Further, as in the invention according to claim 5, by inserting the hollow portion forming member from the second inner wall surface of the mold, the insertion amount of the hollow portion forming member is at least reliably ensured that the pair of electrode wires in the thermistor molded body. A hollow part can be interposed between them. Further, since the hollow portion forming member is inserted from the second inner wall surface facing the first inner wall surface of the mold, the hollow portion forming member can be easily inserted without much consideration of the protrusion of the electrode wire. it can.

  Hereinafter, an embodiment of a thermistor element manufacturing method embodying the present invention will be described with reference to the drawings. First, the structure of the thermistor element 1 which is an example of the thermistor element manufactured using the manufacturing method which concerns on this invention is demonstrated with reference to FIGS. FIG. 1 is a perspective view of the thermistor element 1. FIG. 2 is a front view of the thermistor element 1. FIG. 3 is a left side view of the thermistor element 1. FIG. 4 is a plan view of the thermistor element 1. For convenience, the extending direction of the pair of electrode wires 30 and 40 is set in the vertical direction, and the side on which the main body 10 is formed is the upper side, the parallel direction of the electrode wires 30 and 40 orthogonal to the vertical direction is the width direction, and both directions The direction orthogonal to the front and back directions will be described.

  As shown in FIGS. 1 to 4, the thermistor element 1 includes a body portion 10 made of a thermistor material made of ceramic powder as a raw material and platinum or a platinum alloy (for example, platinum-rhodium alloy). It is comprised from a pair of electrode wire 30 and 40 from which the one end parts 32 and 42 protrude from the side surface (it is set as the bottom face 12 for convenience).

  As for the main-body part 10, the front surface 13 and the back surface 14 comprise the same hexagon shape, are formed in the column shape extended short in the front and back direction, and each surface is each formed in planar shape. Two side surfaces opposed to each other in the vertical direction, that is, the top surface 11 and the bottom surface 12 are each formed in the same rectangular shape including a plane orthogonal to the vertical direction. The two side surfaces constituting the left side surface of the main body 10, that is, the upper left side surface 15 with one side connected to the top surface 11, and the lower left side surface 17 with one side connected to the bottom surface 12 are substantially the vertical direction of the main body unit 10. They are connected to each other so that the ridge angle forms an obtuse angle at the center. Similarly, the two side surfaces constituting the right side surface of the main body 10, that is, the upper right side surface 16 with one side connected to the top surface 11 and the lower right side surface 18 with one side connected to the bottom surface 12 are also the same. They are connected to each other substantially at the center in the vertical direction, and the ridge angle forms an obtuse angle and faces the lower left side surface 17 and the upper left side surface 15 respectively.

  The electrode lines 30 and 40 are formed in a long and narrow columnar shape with the respective axes P and Q extending in the vertical direction, and the other end portions 31 and 41 are arranged on the bottom surface 12 of the main body portion 10 in a state of being arranged in parallel in the width direction. It is embed | buried in the main-body part 10 from the position of the front-back direction approximate center. That is, the one end portions 32, 42 opposite to the other end portions 31, 41 of the electrode wires 30, 40 protrude perpendicularly from the bottom surface 12 of the main body portion 10. The electrode wires 30 and 40 are terminals for electrical connection with a circuit board (not shown), an MI cable, or a lead wire. The body portion 10 is provided between the electrode wires 30 and 40, and the resistance value changes according to the temperature. A certain gap is provided between the electrode wires 30 and 40 so that the thermistor material is interposed. The other end portions 31 and 41 of the electrode wires 30 and 40 penetrate the main body portion 10 in the vertical direction, and the respective front end surfaces 33 and 43 are exposed on the top surface 11 of the main body portion 10.

  By the way, an adjustment hole 20 as a hollow portion is drilled toward the inside of the main body 10 at a position approximately in the center between the electrode wires 30 and 40 on the top surface 11 of the main body 10. The adjustment hole 20 is formed along the axis O of the adjustment hole forming pin 170 of the mold 100 to be described later, and is formed in a cylindrical shape from the top surface 11 to the vicinity of the center along the vertical direction of the main body portion 10. The bottom surface 21 is formed in a planar shape perpendicular to the vertical direction. That is, the depth of the adjustment hole 20 depends on the insertion amount L (see FIG. 6) of the adjustment hole forming pin 170 into the internal space S for forming the main body portion 10. In the thermistor element 1 of the present embodiment, the adjustment hole 20 is formed between the electrode wires 30 and 40 in the main body portion 10, thereby limiting the resistance between the two due to the restriction of the path of the current flowing between them. It is responsible for the rise in value.

  The thermistor element 1 having such a configuration is formed by firing after molding using the mold 100. Hereinafter, a method for manufacturing the thermistor element 1 of the present embodiment will be described with reference to FIGS. FIG. 5 is a perspective view showing a schematic configuration of a mold 100 used for manufacturing the thermistor element 1. FIG. 6 is a view for explaining an arrangement step in the manufacturing process of the thermistor element 1 using a cross-sectional view of the mold 100 as viewed in the direction of the arrows along the two-dot chain line AA in FIG. 5. FIG. 7 is a view for explaining an arrangement step in the manufacturing process of the thermistor element 1 using a cross-sectional view of the mold 100 as viewed in the direction of the arrows along the two-dot chain line BB in FIG. 6. FIG. 8 is a diagram for explaining a pressing process in the manufacturing process of the thermistor element 1 using a cross-sectional view of the mold 100 as viewed in the direction of the arrows along the two-dot chain line AA in FIG. 5. FIG. 9 is a diagram for explaining a drawing process in the manufacturing process of the thermistor element 1 using a cross-sectional view of the mold 100 as viewed in the direction of the arrows along the two-dot chain line BB in FIG. 6. FIG. 10 is a view for explaining demolding of the thermistor molded body 200 during the manufacturing process of the thermistor element 1 using a cross-sectional view of the mold 100 as viewed in the direction of the arrows along the two-dot chain line BB in FIG. 6. is there. For convenience, the opening / closing direction of the female mold 110 of the mold 100 will be described as the front-rear direction of the mold 100, the opening / closing direction of the male mold 120 orthogonal to the front-rear direction will be the top-down direction, and the direction orthogonal to both directions will be described as the left-right direction. . The thermistor molded body 200 formed by the mold 100 is molded with the front and back directions of the thermistor element 1 after firing set to the top-and-bottom direction of the mold 100 and the up and down direction of the mold 100.

  First, a schematic structure of a mold 100 used for manufacturing the thermistor element 1 will be described. As shown in FIG. 5, the mold 100 includes a female mold 110 having a through hole 115 penetrating the center in the vertical direction, a male mold 120 inserted through the through hole 115, and a female mold 110. The adjustment hole forming pin 170 is inserted into the insertion hole 135 penetrating the first female mold 130 in one of the two molds in the front-rear direction.

  The female mold 110 is divided into two in the front-rear direction, one of which is configured as a first female mold 130 and the other as a second female mold 140. The first female mold 130 has a groove shape composed of three inner surfaces 131, 132, and 133, and a groove portion 134 that connects both ends in the vertical direction is formed at a substantially horizontal center of the mating surface 138 with the second female mold 140. ing. Similarly, the second female mold 140 has a groove-shaped groove 144 formed of three inner surfaces 141, 142, and 143 on the mating surface 148 with the first female mold 130. When the second female mold 140 and the second female mold 140 are combined by closing the mold, the above-described through-hole 115 is formed by both the groove portions 134 and 144. The through-hole 115 has each groove portion 134, such that the shape of the cross section in the top-and-bottom direction, which is the penetration direction of the through-hole 115, is a hexagonal shape substantially equal to the shape of the front surface 13 of the body portion 10 of the thermistor element 1 (see FIG. 2). Each inner surface 131-133, 141-143 of 144 is arrange | positioned. In particular, the inner surfaces 132 and 142 forming the bottoms of the grooves 134 and 144 are each formed in a planar shape orthogonal to the front-rear direction.

  Further, the first female mold 130 is provided with an insertion hole 135 that penetrates in the front-rear direction at the approximate center of the inner surface 132 of the groove 134. The insertion hole 135 has an elongated hole-shaped adjustment hole forming pin for forming the adjustment hole 20 of the main body 10 of the thermistor element 1 described above from the back surface 139 side opposite to the mating surface 138. 170 is inserted in the through-hole 115 so that the distal end portion 171 can be withdrawn / retracted, with its own axis O direction along the front-rear direction which is the insertion direction. The adjustment hole forming pin 170 has an outer diameter substantially equal to the inner diameter of the insertion hole 135, and its tip end surface 172 is formed in a planar shape perpendicular to the direction of the axis O. For example, a piano wire can be used as the adjustment hole forming pin 170. The adjustment hole forming pin 170 corresponds to the “hollow portion forming member” in the present invention. The inner surface 132 corresponds to a “second inner wall surface” in the present invention, and the insertion hole 135 corresponds to an “insertion port” in the present invention.

  Similarly, the second female die 140 is also provided with a pair of insertion holes 145 and 146 penetrating in the front-rear direction at the approximate center of the inner surface 142 of the groove 144. The pair of insertion holes 145 and 146 are provided substantially in parallel in the left-right direction at substantially the same position in the top-and-bottom direction, and the electrode lines of the thermistor element 1 are arranged from the back surface 149 side opposite to the mating surface 148. 30 and 40 are respectively inserted. Each electrode wire 30, 40 is inserted with its own axis P, Q direction along the front-rear direction which is the insertion direction to the insertion holes 145, 146 when the mold is closed, and each other end portion in the through hole 115. It arrange | positions in the state which exposed 31 and 41. FIG. In addition, the inner diameters of the insertion holes 145 and 146 are formed to be approximately equal to the outer diameters of the electrode wires 30 and 40, respectively, and the arrangement interval between them is the arrangement interval of the electrode wires 30 and 40 of the thermistor element 1 after formation. It is almost equivalent. The inner surface 142 corresponds to the “first inner wall surface” in the present invention.

  On the other hand, the male mold 120 includes a first male mold 150 inserted from above along the through-hole 115 of the female mold 110 and a second male mold 160 inserted from below. Both the first male mold 150 and the second male mold 160 are configured in a hexagonal column shape having substantially the same cross-sectional shape as the front surface 13 of the main body 10 of the thermistor element 1. The opposing surfaces 151 and 161 of the first male mold 150 and the second male mold 160 are formed in a planar shape perpendicular to the top and bottom direction. By closing the female mold 110 and the male mold 120, an internal space S (see FIG. 6) for forming the thermistor molded body 200 of the thermistor element 1 is formed in the mold 100.

Next, a method for manufacturing the thermistor element 1 using the mold 100 having the above structure will be described. The thermistor element 1 is made of a thermistor material made of ceramic powder as a raw material, and is formed by firing a thermistor molded body 200 formed by pressing a ceramic powder using a mold 100. In the manufacturing process of the thermistor element 1, first, ceramic powder is prepared. Specifically, Y ₂ O ₃ , SrCO ₃ , Cr ₂ O ₃ , Fe ₂ O ₃ , and TiO ₂ are wet-mixed at a predetermined mixing ratio, dried, and then calcined by holding at 1400 ° C. for 2 hours. . Then, a sintering aid is wet mixed with the obtained powder, pulverized, and dried to obtain a dry powder. Further, a binder and acetone are added to this dry powder, and the powder obtained by drying is sized to obtain ceramic powder M for press (see FIG. 6).

  In order to press the ceramic powder, the mold 100 shown in FIG. 5 is closed. As shown in FIGS. 6 and 7, the first female mold 130 is moved to the second female mold 140 side along the front-rear direction (left and right direction on the paper surface of FIGS. 6 and 7), and the mold closing of the female mold 110 is performed. Done. The mating surfaces 138 and 148 are brought into contact with each other, and a through-hole 115 having a hexagonal cross section is formed by the grooves 134 and 144. Next, of the male mold 120, the second male mold 160 is inserted into the through hole 115 from below along the vertical direction. Then, the electrode lines 30 and 40 are inserted into the insertion holes 145 and 146 from the back surface 149 side of the second female mold 140 with their own axes P and Q along the longitudinal direction of the mold 100. At this time, the other end portions 31 and 41 of the electrode wires 30 and 40 are disposed in the internal space S, and the respective end surfaces 33 and 43 are brought into contact with the inner surface 132 of the groove portion 134 of the first female die 130, respectively. The Furthermore, the adjustment hole forming pin 170 is inserted into the insertion hole 135 from the back surface 139 side of the first female mold 130 with its own axis O along the longitudinal direction of the mold 100. At this time, the adjustment hole forming pin 170 is inserted into the insertion hole 135 in accordance with a predetermined insertion amount L, and the distal end portion 171 is disposed in the internal space S. Then, in the internal space S, the adjustment hole forming pin 170 is positioned and fixed with respect to the first female die 130 in a state where the position of the front end surface 172 is a predetermined position in the front-rear direction (arrangement step). In addition, according to the positional relationship between the insertion hole 135 of the first female mold 130 and the insertion holes 145 and 146 of the second female mold 140, in the internal space S, between the other end portions 31 and 41 of the electrode wires 30 and 40, respectively. In addition, the tip end portion 171 of the adjustment hole forming pin 170 is disposed.

  Then, the ceramic powder M is filled in the internal space S. Further, the first male mold 150 is inserted into the through-hole 115 from above along the top-to-bottom direction. In this state, as shown in FIG. 8, the first male mold 150 and the second male mold 160 are pressed in a direction in which the opposing surfaces 151 and 161 approach each other along the top-and-bottom direction by a pressing device (not shown). The ceramic powder M filled in S is pressed and compacted (pressing process). Thereby, the thermistor molded body 200 (that is, the unfired thermistor element 1) in which the other end portions 31 and 41 of the electrode wires 30 and 40 are respectively pressure-bonded to the ceramic powder M is formed by press molding.

  Next, the adjustment hole forming pin 170 is extracted. As shown in FIG. 9, the adjustment hole forming pin 170 is extracted from the insertion hole 135 of the first female mold 130 with its own axis O along the front-rear direction (extraction process). Next, the mold 100 is opened. The mold opening is performed in the reverse order of mold closing. First, the first male mold 150 is moved upward along the vertical direction, and then the second male mold 160 is moved downward along the vertical direction. Further, as shown in FIG. 10, the first female mold 130 is moved in the direction away from the second female mold 140 along the front-rear direction. Then, the thermistor molded body 200 is taken out from the mold 100 by the electrode wires 30 and 40 being pushed into the internal space S through the insertion holes 145 and 146.

  By the way, the bottom surface 212 of the body portion 210 of the thermistor molded body 200 that becomes the body portion 10 after firing is formed by the inner surface 142 of the second female mold 140. As described above, since the inner surface 142 is formed in a planar shape orthogonal to the front-rear direction, the bottom surface 212 is formed in a planar shape orthogonal to the respective axes P and Q directions of the electrode lines 30 and 40. For this reason, when the thermistor molded body 200 is removed from the second female mold 140, the thermistor molded body 200 is taken out along the axes P and Q of the electrode wires 30 and 40, respectively. There is no friction between the inner surface 142. In particular, the vicinity of the base from which the electrode wires 30 and 40 protrude from the bottom surface 212 is a relatively low strength portion in the main body 210, but friction between the bottom surface 212 and the inner surface 142 does not occur, so the electrode wires 30 and 40 and the main body Peeling with the portion 210 is unlikely to occur, and the thermistor molded body 200 is effectively prevented from being damaged. This effect is the same on the top surface 211 side of the main body 210.

  The thermistor molded body 200 removed from the mold 100 is put into a firing furnace and fired at 1550 ° C. in the atmosphere, whereby the thermistor element 1 is completed (firing step).

  The thermistor element 1 formed in this way is formed by the planar top surface 11 to be formed by the inner surface 132 of the first female die 130 of the mold 100 and the inner surface 142 of the second female die 140. The planar bottom surface 12 is parallel to each other and is orthogonal to the axes P and Q of the electrode lines 30 and 40. In addition, a certain gap is provided between the electrode wires 30 and 40, and the distal end surfaces 33 and 43 reach the top surface 11, so that they are interposed between the electrode wires 30 and 40 in the main body 10. Therefore, the capacity of the thermistor material to be obtained is almost constant regardless of manufacturing variations. In this state, due to the adjustment hole 20 formed from the top surface 11 side, a portion where the thermistor material is not interposed is formed in a part between the electrode wires 30 and 40. In that part, since the current flowing between the electrode wires 30 and 40 bypasses the adjustment hole 20, the resistance value increases or is in an insulated state. The resistance value between the electrode lines 30 and 40 in the entire portion 10 can be increased.

  Here, since the axis O of the adjustment hole forming pin 170 for forming the adjustment hole 20 is provided in parallel with the axes P and Q, only the depth of the adjustment hole 20 is adjusted at the design stage of the thermistor element 1. The resistance value of the current flowing between the electrode lines 30 and 40 can be easily adjusted. Further, since the tip end surface 172 of the adjustment hole forming pin 170 is formed in a plane shape orthogonal to the axis O, the insertion amount L of the tip end portion 171 of the adjustment hole forming pin 170 into the internal space S of the mold 100 is achieved. That is, the depth of the adjustment hole 20 to be formed can be adjusted easily and stably.

  At this time, since the tip surfaces 33 and 43 of the electrode wires 30 and 40 reach the top surface 11 as described above, a relatively shallow adjustment hole is sufficient for forming the adjustment hole 20 on the top surface 11 side. An effect of increasing the resistance value between the electrode wires 30 and 40 can be obtained. This makes it possible to reduce the proportion of the adjustment hole 20 in the main body 10 in obtaining the target resistance value, and prevent a decrease in mechanical strength. Since the adjustment hole forming pin 170 is cylindrical, the inner peripheral surface of the adjustment hole 20 to be formed has no corners, which is preferable in terms of maintaining the strength of the main body 10. Further, when extracting from the thermistor molded body 200, if it is extracted while twisting about the axis O, it is possible to easily extract without damaging the main body 210.

  Thus, in the design of the thermistor element 1, the resistance value between the electrode wires 30, 40 can be adjusted without changing the size of the main body 10 and the distance between the electrode wires 30, 40. Even when the composition is changed, it is possible to easily produce a thermistor element having a target resistance value using the same mold 100, and to reduce the manufacturing cost.

  Needless to say, the present invention can be modified in various ways. For example, the electrode wires 30 and 40 may be prismatic. Similarly, the adjustment hole forming pin 170 may have a prismatic shape. However, in view of maintaining the mechanical strength of the main body 10 due to the shape of the adjustment hole 20 to be formed, the adjustment hole 20 has a shape with as few corners as possible. It is preferable that the shape is a cylinder as in this embodiment. Of course, the tip surface 172 may be hemispherical, pyramidal, or conical, and such a shape is better when viewed from the mechanical strength surface of the main body 10. However, considering the ease and stability of adjusting the resistance value between the electrode wires 30 and 40 depending on the depth of the adjustment hole 20, the tip surface is preferably a plane orthogonal to the axis O.

  Further, in order to prevent the influence of the resistance value change due to the entry of foreign matter into the adjustment hole 20 when the thermistor element 1 is used, the adjustment hole 20 is filled with an insulator having high temperature heat resistance (for example, alumina powder or the like). Also good.

  Moreover, although the shape of the front surface 13 of the thermistor element 1 is a hexagonal shape, it may be at least a polygonal shape that is equal to or greater than a quadrangle, and as the number of corners increases, the angle of one corner is made more obtuse and the mechanical strength increases. desirable. Furthermore, a circular shape may be sufficient. However, it is desirable that the bottom surface 12 be formed in a planar shape, as in the present embodiment, from the viewpoint of preventing the occurrence of cracks when being extracted from the mold. For example, the front may have a circular shape and a portion corresponding to the bottom surface 12 may be cut into a flat shape. Further, if the portion corresponding to the top surface 11 is also cut into a flat shape, it is preferable to suppress variation in the manufacturing of the capacity of the thermistor material that is interposed between both electrode lines in the main body. .

  In the present embodiment, the tip surfaces 33 and 43 of the electrode wires 30 and 40 are configured to reach the top surface 11 of the main body 10, but the tip surfaces 33 and 43 are not configured to reach the top surface 11. There may be a configuration in which the distal ends of the distal end portions 31 and 41 protrude from the top surface 11. For example, even in the case where the front end surfaces 33 and 43 are arranged on the way from the bottom surface 12 to the top surface 11 in the main body 10, both electrodes are formed if a part of the adjustment hole 20 is formed on the bottom surface 12 side from the position. The resistance value between the lines 30 and 40 can be adjusted. The adjustment hole 20 may also be formed from the bottom surface 12 side, or may be formed from the front surface 13 side and the back surface 14 side. Furthermore, it may be formed in a through hole shape that allows the front surface 13 and the back surface 14 to communicate with each other. In this case, the resistance value between the electrode lines 30 and 40 can be adjusted by the opening area of the through hole. In other words, it is sufficient if these adjustment holes are formed so as to block between the electrode wires 30 and 40 in the main body 10. However, considering the viewpoint of maintaining the mechanical strength of the main body 10 and the design convenience of the mold as described above, the configuration in which the adjustment hole 20 is formed from the top surface 11 side as in the present embodiment. It is desirable that

  Further, in the arranging step, the adjustment hole forming pin 170 is arranged after arranging the pair of electrode wires 30 and 40 on the mold 100. However, the electrode wire 30 is arranged after the adjusting hole forming pin 170 is arranged. , 40 may be arranged, or the electrode wires 30, 40 and the adjustment hole forming pin 170 may be arranged simultaneously. Furthermore, the adjustment hole forming pin 170 may be positioned and fixed to the first female die 130 in advance before the thermistor element 1 is manufactured. In this way, the adjustment hole forming pin 170 can be disposed in the internal space S by simply closing the female mold 110, and the adjustment hole from the thermistor molded body 200 can be simply opened. The forming pin 170 can be removed. Further, when the mold is opened, the fixing with the first female mold 130 is released so that the adjustment hole forming pin 170 remains on the thermistor molded body 200 side, and the adjustment hole forming pin 170 is removed after the thermistor molded body 200 is removed from the mold. You may go.

  For convenience of explanation, the thickness of the mold 100 is not taken into account in the drawings. For example, if the female mold 110 has a large thickness in the front-rear direction, the electrode wire inserted into the insertion holes 135, 145, 146 It is easy to align the axis of pins and pins in the front-rear direction, and more reliable axis alignment is possible.

  The present invention can be applied to a thermistor element manufacturing method.

3 is a perspective view of the thermistor element 1. FIG. 2 is a front view of the thermistor element 1. FIG. 3 is a left side view of the thermistor element 1. FIG. 3 is a plan view of the thermistor element 1. FIG. 2 is a perspective view showing a schematic configuration of a mold 100 used for manufacturing the thermistor element 1. FIG. FIG. 6 is a diagram for explaining an arrangement process in the manufacturing process of the thermistor element 1 using a cross-sectional view of the mold 100 as viewed in the direction of the arrows along the two-dot chain line AA in FIG. 5. It is a figure for demonstrating the arrangement | positioning process in the manufacture process of the thermistor element 1 using sectional drawing of the metal mold | die 100 seen from the arrow direction in the dashed-two dotted line BB of FIG. FIG. 6 is a diagram for explaining a pressing process in the manufacturing process of the thermistor element 1 using a cross-sectional view of the mold 100 as viewed in the direction of the arrows along the two-dot chain line AA in FIG. 5. It is a figure for demonstrating the extraction process in the manufacture process of the thermistor element 1 using sectional drawing of the metal mold | die 100 seen from the arrow direction in the dashed-two dotted line BB of FIG. It is a figure for demonstrating the demolding of the thermistor molded object 200 in the manufacture process of the thermistor element 1, using sectional drawing of the metal mold | die 100 seen from the arrow direction in the dashed-two dotted line BB of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermistor element 10 Main-body part 30,40 Electrode wire 31,41 The other end part 32,42 One end part 100 Mold 132,142 Inner surface 135 Insertion hole 170 Adjustment hole formation pin 200 Thermistor molded object S Internal space M Ceramic powder

Claims (5)

A thermistor element manufacturing method comprising: a main body portion made of a thermistor material; and a pair of electrode wires embedded in the main body portion and at least one end portion projecting outside the main body portion,
The pair of electrode wires are arranged in the mold so that a part of the pair of electrode wires is arranged at a predetermined interval in the inner space of the mold into which the thermistor material will be charged. On the other hand, the hollow portion forming member capable of adjusting the insertion amount of the mold into the internal space is arranged such that a part of itself is located between the electrode wires and according to a predetermined insertion amount. A placement process for placing in the mold;
After the placing step, the thermistor material is put into the inner space of the mold and press-molded to form a thermistor molded body in which a part of the pair of electrode wires and the hollow portion forming member is embedded. Process,
An extraction step of extracting the hollow portion forming member from the thermistor molded body;
A thermistor molded body after the extraction step is fired to obtain the thermistor element.   The method for manufacturing a thermistor element according to claim 1, wherein the hollow portion forming member has a cylindrical shape, and the amount of insertion into the mold is adjusted along the axial direction thereof.   When the pair of electrode wires is disposed on the mold, the first inner wall surface including the portion from which the pair of electrode wires protrudes among the inner wall surfaces constituting the internal space of the mold, 3. The method of manufacturing the thermistor element according to claim 1, wherein the thermistor element is formed in a planar shape perpendicular to the protruding direction of the pair of electrode wires.   When the pair of electrode wires is disposed in the mold, the other end of the pair of electrode wires opposite to the one end is exposed in the internal space, and the other ends are respectively The method of manufacturing a thermistor element according to any one of claims 1 to 3, wherein the thermistor element reaches a second inner wall face that faces the first inner wall face across the inner space.   An insertion port for inserting the hollow portion forming member, a part of which is disposed between the pair of electrode wires in the inner space of the mold, is provided in the second inner wall surface. The method of manufacturing a thermistor element according to claim 4.

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