JP6384337B2 - Temperature sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a temperature sensor and a manufacturing method thereof.

  2. Description of the Related Art A temperature sensor in which a metal lead wire electrically connected to a temperature sensing element that senses temperature is inserted into a resin casing by insert molding has been conventionally known.

  For example, Patent Document 1 discloses a technique in which a primary mold resin is interposed between a resin casing as a secondary mold resin and a metal lead wire in a sensor device used as a temperature sensor or the like. In such a technique, the primary expansion resin and the secondary mold resin have different linear expansion coefficients in the flow direction and the flow direction perpendicular to the molten resin material at the time of molding.

JP 2004-198240 A

  Now, under the configuration in which the metal lead wire is linearly stretched as in the technique disclosed in Patent Document 1, the flow direction of the molten resin material at a location where the metal lead wire in the molding cavity is close to the gate in the molding die. Becomes easy to follow along the said extending | stretching direction. However, in the molding die, at the location where the metal lead wire in the molding cavity is far from the gate, the flow direction of the molten resin material becomes difficult to follow the extending direction of the metal lead wire. Therefore, with the technique disclosed in Patent Document 1, it is difficult to appropriately set the magnitude relationship between the linear expansion coefficient of the primary mold resin and the linear expansion coefficient of the metal lead wire in the extending direction of the metal lead wire. In particular, in a sensor device as a temperature sensor assumed to be used in a high-temperature environment, the thermal expansion amount of the primary mold resin is larger than the thermal expansion amount of the metal lead wire in the extending direction of the metal lead wire. Therefore, if the linear expansion coefficient is not properly set, the metal lead wire that is pulled in the extending direction by the primary mold resin that has undergone large thermal expansion may cause a disconnection due to the occurrence of stress, thereby reducing the yield.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a temperature sensor with a high yield and a method for manufacturing the same.

  The first invention disclosed in order to solve the above-described problem includes a temperature-sensitive element (10) for sensing temperature, and an extending portion (21) formed from a metal material and extending along the reference direction (Db). A metal lead wire (20, 20a, 20b) electrically connected to the temperature sensing element, a resin casing (40) formed from a resin material and inserted with a metal lead wire by molding, An intermediate cover (50) formed from a specific material that has a linear expansion coefficient larger than that of the metal lead wire and smaller than that of the resin casing in the reference direction, and interposed between the resin casing and the metal lead wire; The difference in the linear expansion coefficient between the lead wire and the intermediate cover is a specification that limits the stress generated in the metal lead wire to be smaller than the tensile strength of the metal lead wire according to the difference in the linear expansion coefficient. In circumference, characterized in that it is set.

  In the first invention, an intermediate cover is interposed between the metal lead wire inserted into the resin casing by molding and the casing. Here, in the reference direction in which the extending portion of the metal lead wire extends, the linear expansion coefficient of the intermediate cover is given larger than the metal lead wire and smaller than the resin casing by the specific material forming the cover. Therefore, even under use in a high temperature environment, in the reference direction, the thermal expansion amount of the intermediate cover can be as close as possible to the thermal expansion amount of the metal lead wire rather than the thermal expansion amount of the resin casing. Moreover, since the difference in linear expansion coefficient between the metal lead wire and the intermediate cover in the reference direction is set within a specific range, the stress generated on the metal lead wire in accordance with the set value is smaller than the tensile strength of the metal lead wire. Limited. Thereby, in the metal lead wire, it is possible to suppress a situation in which the generated stress exceeds the tensile strength and causes disconnection, and thus it is possible to achieve a high yield.

  According to the second invention, the resin casing is formed by molding from a resin material containing a fibrous filler, and the linear expansion coefficient of the intermediate cover in the reference direction is smaller than the minimum linear expansion coefficient of the resin casing. It is characterized by that.

  When a resin casing is molded from a resin material containing a fibrous filler as in the second invention, the linear expansion coefficient in each part of the resin casing may vary depending on the gate formation position in the molding die. . Therefore, in the reference direction, as long as the difference between the linear expansion coefficients of the intermediate cover formed of a specific material and the metal lead wire having a smaller linear expansion coefficient is within a specific range, It is given smaller than the linear expansion coefficient. According to this, since the thermal expansion amount of the intermediate cover surely approaches the thermal expansion amount of the metal lead wire rather than the thermal expansion amount at an arbitrary location of the resin casing, the generated stress is higher than the tensile strength in the lead wire. The wire breakage can be suppressed by being limited to a small size. Therefore, it is possible to contribute to achieving a high yield.

  Furthermore, the third invention is a method of manufacturing the temperature sensor of the second invention, wherein a pair of metal lead wires is covered with an intermediate cover (S101), and a pair of the cover covered with the intermediate cover in the covering step. In the molding step, the metal lead wires are arranged in a direction orthogonal to the reference direction (Do) and set together with the temperature sensitive element in the molding cavity (101) of the molding die (100). The molten resin material from the gate (102) provided on one of the two sides sandwiching the pair of metal lead wires set in the setting step in the orthogonal direction toward one side and the other side of the both sides Injection step (S103) for injecting the resin into the molding cavity, and by solidifying the resin material injected into the molding cavity in the injection step, A solidification step of forming a single (S104), characterized in that it contains.

  In the third invention, the pair of metal lead wires covered with the intermediate cover are arranged in a direction orthogonal to the reference direction, and set together with the temperature sensitive element into the molding cavity of the molding die. In such a molding die, a molten resin material is formed from a gate provided on one side of both sides sandwiching a pair of set metal lead wires in an orthogonal direction toward one side and the other side of the both sides. Will be injected into the molding cavity. As a result, in the resin casing formed by solidification of the molten resin material injected into the molding cavity, around the metal lead wire on one side close to the gate, than around the metal lead wire on the other side far from the gate A higher coefficient of linear expansion is given in the reference direction. This is because the molten resin material flows along the reference direction around the metal lead wire on one side, whereas the molten resin material does not follow the reference direction around the metal lead wire on the other side. This is because a difference occurs in the fiber orientation of the fibrous filler.

  However, in the reference direction of the temperature sensor manufactured according to the third invention, the linear expansion coefficient of the intermediate cover is as long as the linear expansion coefficient difference with the smaller linear expansion coefficient of each metal lead wire is within a specific range. It is given smaller than the minimum linear expansion coefficient of the resin casing. According to this, since the thermal expansion amount of the intermediate cover surely approaches the thermal expansion amount of each metal lead wire rather than the thermal expansion amount at an arbitrary position of the resin casing, the generated stress is tensile in each of the metal lead wires. The disconnection can be suppressed by being limited to be smaller than the strength. Therefore, it is possible to contribute to achieving a high yield.

It is a figure which shows the structure of the temperature sensor by one Embodiment, Comprising: It is the II sectional view taken on the line of FIG. It is a figure which shows the structure of the temperature sensor by one Embodiment, Comprising: It is the II-II sectional view taken on the line of FIG. It is a physical property table | surface for demonstrating the physical property of the temperature sensor by one Embodiment. It is the top view (a), side view (b), and perspective view (c) which show a temperature sensing element, a metal lead wire, and a metal terminal as a component of the temperature sensor by one Embodiment. It is the top view (a), side view (b), and perspective view (c) which show a metal terminal and an intermediate | middle cover as a component of the temperature sensor by one Embodiment. It is the top view (a), side view (b), and perspective view (c) which show the external appearance of the temperature sensor by one Embodiment. It is a flowchart which shows the manufacturing method of the temperature sensor by one Embodiment. It is sectional drawing shown about S101 of FIG. It is sectional drawing shown about S102 of FIG. It is sectional drawing shown about S103 of FIG. It is sectional drawing shown about S104 of FIG. It is sectional drawing which shows the modification of FIG.

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

  A temperature sensor 1 shown in FIGS. 1 and 2 as an embodiment of the present invention is mounted inside a front grille in an engine room of a vehicle. The temperature sensor 1 senses the temperature of the outside air of the vehicle. As shown in FIG. 3, the temperature sensor 1 has a difference between the lowest temperature reached by the vehicle outside air in a cold environment and the highest temperature reached by radiant heat from the engine in a vehicle that is stopped or traveling at a low speed, An operating temperature range ΔT is defined. Here, in the numerical example of FIG. 3, a wide-range operating temperature range ΔT of 110 ° C. is assumed in advance as the difference between the lowest temperature of −30 ° C. and the highest temperature of 80 ° C.

  First, the configuration of the temperature sensor 1 will be described in detail. As shown in FIGS. 1 and 2, the temperature sensor 1 includes a temperature sensitive element 10, a metal lead wire 20, a metal terminal 30, a resin casing 40, and an intermediate cover 50.

  The temperature sensing element 10 shown in FIGS. 1, 2 and 4 is a thermistor that generates a sensing signal having a voltage corresponding to the sensed temperature in order to sense the temperature of the outside air of the vehicle. The temperature sensitive element 10 is formed by sealing the entire element body 11 with a sealing material 12. The sealing material 12 is formed from a material that exhibits heat resistance in the operating temperature range ΔT, such as an epoxy resin, glass, or the like. In the present embodiment, the sealing material 12 is oblate, but may be, for example, a rectangular or circular flat plate. The element body 11 shown in FIGS. 1 and 2 is formed of a material whose electrical resistance changes according to a change in temperature, such as a ceramic material, a metal oxide material, or a resin material containing conductive particles. The element body 11 has a rectangular chip shape in the present embodiment, but may be, for example, a circular chip shape.

  A pair of metal lead wires 20 shown in FIGS. 1, 2, and 4 are provided to output a sensing signal generated by the temperature sensing element 10. Each metal lead wire 20 has an extending portion 21 extending linearly along a predetermined reference direction Db. The metal lead wires 20 are arranged at intervals in an orthogonal direction Do orthogonal to the reference direction Db, thereby extending the extending portions 21 substantially parallel to each other along the reference direction Db. Furthermore, each metal lead wire 20 is integrally provided with an inclined portion 22 that is inclined toward each other with respect to the reference direction Db by extending from the extending portion 21 toward the common temperature-sensitive element 10. Yes. The inclined part 22 of each metal lead wire 20 is electrically connected to the common element 10 by being joined to the common temperature sensitive element 10 by, for example, welding. Each metal lead wire 20 having such a configuration is formed of a conductive metal material such as copper, iron, stainless steel, or the like. Each metal lead wire 20 has an elongated round bar shape as a whole in the present embodiment, but may be, for example, an elongated flat plate shape.

As shown in FIG. 3, the metal lead wires 20 are given substantially the same linear expansion coefficient αl and substantially the same Young's modulus Yl with respect to the reference direction Db. Specifically, in the numerical example of FIG. 3, 1.2 × 10 ⁻⁵ / ° C. is given as the linear expansion coefficient αl defined in the reference direction Db of the metal lead wire 20 formed of annealed copper wire. In the numerical example of FIG. 3, 152.0 GPa (kN / mm ² ) is given as the Young's modulus Yl defined in the reference direction Db of the metal lead wire 20 formed from an annealed copper wire.

A pair of metal terminals 30 shown in FIGS. 1, 2, 4 and 5 are provided corresponding to the lead wires 20 individually in order to transmit a sensing signal output through the metal lead wires 20 to an external circuit. . Each metal terminal 30 is electrically connected to the corresponding lead wire 20 by being joined to the extending portion 21 of the corresponding metal lead wire 20 by welding or the like, for example. Each metal terminal 30 is linearly extended along the reference direction Db from the joint portion with the corresponding metal lead wire 20, and is aligned in the orthogonal direction Do orthogonal to the same direction Db. Each metal terminal 30 is formed from a conductive metal material, for example, copper, iron, dumet wire (material in which an iron-nickel alloy is coated with copper) and the like. Each metal terminal 30 has an elongated rectangular flat plate shape in the present embodiment, but may have an elongated round bar shape, for example. For each of such metal terminals 30, for example, a strength of about 390 to 500 N / mm ² is given as the tensile strength so that the tensile strength in the reference direction Db is higher than that of the corresponding metal lead wire 20. .

  As shown in FIGS. 1, 2, and 6, the resin casing 40 is formed by inserting the entire temperature sensing element 10, the entire metal lead wires 20, and a part of each metal terminal 30 by molding. The resin casing 40 exposes the remainder of the terminals 30 to the outside so that the metal terminals 30 can be electrically connected to an external circuit. The resin casing 40 is formed from a resin material exhibiting heat resistance in the use temperature range ΔT, such as polybutylene terephthalate (PBT) resin, polyphenylene sulfide (PPS) resin, or the like. Here, the resin casing 40 of the present embodiment is formed of a resin material containing a fibrous filler such as a glass filler, for example, in order to increase the impact strength in the vehicle. In order to form the resin casing 40 made of such a resin material, a single-sided gate type, which will be described later, is employed as the molding in this embodiment.

As shown in FIG. 3, the resin casing 40 is given a linear expansion coefficient αc larger than that of the metal lead wire 20 and a Young's modulus Yc smaller than that of the metal lead wire 20 with respect to the reference direction Db. Specifically, in the numerical example of FIG. 3, 2.0 × 10 ⁻⁵ / ° C. is given as the linear expansion coefficient αc defined in the reference direction Db of the resin casing 40 formed from the glass filler-containing PBT resin. . Moreover, 9.0 GPa is given as the Young's modulus Yc defined in the reference direction Db of the resin casing 40 formed from the glass filler-containing PBT resin.

Here, in the resin casing 40 formed from a glass filler-containing specific material by one-side gate type molding described later, around the one side metal lead wire 20a (see FIG. 1), the other side metal lead wire. A linear expansion coefficient αc smaller than that around 20b (see FIG. 1) is given in the reference direction Db. As a result, the linear expansion coefficient αc shows a minimum value around the metal lead wire 20a on one side. Therefore, in the numerical example of FIG. 3, 2.0 × 10 ⁻⁵ / ° C. is presented as the minimum linear expansion coefficient αc around the metal lead wire 20a on one side.

  Moreover, in the resin casing 40 formed from a glass filler-containing specific material by one-side gate type molding described later, the circumference of the metal lead wire 20a on one side is larger than the circumference of the metal lead wire 20b on the other side. Young's modulus Yc is given in the reference direction Db. As a result, the Young's modulus Yc shows the maximum value around the metal lead wire 20a on one side. Therefore, in the numerical example of FIG. 3, 9.0 GPa is presented as the maximum Young's modulus Yc around the metal lead wire 20a on one side.

  As shown in FIGS. 1, 2, and 5, the intermediate cover 50 is formed by coating the entire temperature sensing element 10, the entire metal lead wires 20, and a part of each metal terminal 30 by a coating process. The intermediate cover 50 is inserted into the resin casing 40 by molding so that the intermediate cover 50 is interposed between the inner elements 10, 20, 30 and the outer casing 40 in a thin film shape. The intermediate cover 50 is formed from a specific material exhibiting heat resistance in the use temperature range ΔT, for example, PPS resin, epoxy resin, silicone resin, or the like. Here, the intermediate cover 50 of the present embodiment is formed from a specific material containing a fibrous filler such as a glass filler, for example, in order to increase the impact strength in the vehicle. As the coating process for forming the intermediate cover 50 from such a specific material, for example, a coating process or a spraying process of the liquid specific material, an immersion process in the liquid specific material, or the like can be employed. Further, as the formation thickness of the intermediate cover 50 by the coating process, for example, a film thickness of about 0.2 to 2 mm is employed.

As shown in FIG. 3, the intermediate cover 50 has a linear expansion coefficient αm larger than the metal lead wire 20 and smaller than the resin casing 40, and a Young's modulus Ym smaller than the metal lead wire 20 and larger than the resin casing 40. Is given for the reference direction Db. Specifically, in the numerical example of FIG. 3, as the linear expansion coefficient αm defined in the reference direction Db of the intermediate cover 50 formed from the glass filler-containing PPS resin by the coating process, from the minimum linear expansion coefficient αc of the resin casing 40 A small 1.6 × 10 ⁻⁵ / ° C. is given. Further, in the numerical example of FIG. 3, the Young's modulus Ym defined in the reference direction Db of the intermediate cover 50 formed from the glass filler-containing PPS resin by the coating process is larger than the maximum Young's modulus Yc of the resin casing 40. ² kN / mm ² GPa is given.

Under such a configuration of the temperature sensor 1, if the linear expansion coefficient difference in the reference direction Db between the metal lead wire 20 and the intermediate cover 50 is defined as Δα, the coefficient difference Δα is expressed by the following formula 1. That is, the linear expansion coefficient difference Δα is obtained by a subtraction value obtained by subtracting the linear expansion coefficient αl in the same direction Db of the metal lead wire 20 from the linear expansion coefficient αm in the reference direction Db of the intermediate cover 50. Specifically, the linear expansion coefficient difference Δα obtained by substituting the numerical example of FIG. 3 into Equation 1 is 0.4 × 10 ⁻⁵ / ° C.
Δα = αm−αl (Formula 1)

Further, when the stress generated in the metal lead wire 20 according to the linear expansion coefficient difference Δα with the intermediate cover 50 is defined as σ, the generated stress σ is expressed by the following formula 2. That is, the generated stress σ is estimated by a multiplication value obtained by multiplying the linear expansion coefficient difference Δα in the reference direction Db by the Young's modulus Yl in the same direction Db of the metal lead wire 20 and the operating temperature range ΔT. Specifically, the generated stress σ estimated by substituting the numerical example of FIG. 3 into Equation 2 is 66.88 N / mm ² .
σ = Δα · Yl · ΔT (Expression 2)

Furthermore, if the tensile strength of the metal lead wire 20 in the reference direction Db is defined as Sl, the temperature sensor 1 satisfies the relationship of the following formula 3 between the generated stress σ in the metal lead wire 20 and the strength Sl. That is, in the metal lead wire 20, the generated stress σ in the metal lead wire 20 is limited to be smaller than the tensile strength S1. Specifically, in the numerical example of FIG. 3, since the tensile strength S1 of the metal lead wire 20 formed of annealed copper wire is 120 N / mm ² , the generated stress σ in the lead wire 20 is 66.88 N as described above. / Mm ² . The tensile strength S1 can be measured by a method such as JIS Z2241 (metal material tensile test method).
σ <Sl (Formula 3)

From the above, when formulas 2 and 3 are arranged, the following formula 4 is obtained. Therefore, in the temperature sensor 1, when the minimum linear expansion coefficient αm of the intermediate cover 50 is given smaller than the linear expansion coefficient αl of the metal lead wire 20, a line obtained by substituting these coefficients αl and αm into Equation 1 is obtained. The expansion coefficient difference Δα is set in advance in a specific range that satisfies the relationship of Equation 4. In such a temperature sensor 1, if the relationship of Formula 4 is established by selecting a specific material for forming the intermediate cover 50 having a linear expansion coefficient αm, the resin material for forming the metal lead wire 20 and the resin casing 40 can be obtained. It becomes possible to increase the degree of freedom of selection.
Δα <Sl / (Yl · ΔT) (Formula 4)

  Next, a manufacturing method executed in accordance with the flowchart of FIG. 7 in order to manufacture the temperature sensor 1 will be described in detail. As a first step of the manufacturing method, in the covering step of S101, a pair of metal lead wires 20 are covered with an intermediate cover 50 as shown in FIG. At this time, in the covering step of this embodiment, the common temperature sensing element 10 joined to each metal lead wire 20 and a part of the individual metal terminal 30 are also covered by the intermediate cover 50. Therefore, in the covering step, for example, the liquid specific material is applied to the whole of the metal lead wires 20, the temperature sensing element 10, and a part of each of the metal terminals 30. A coating process such as a dipping process is performed.

  In the setting step of S102 as the second stage of the manufacturing method, as shown in FIG. 9, the pair of metal lead wires 20 covered with the intermediate cover 50 in the previous covering step is formed of the mold 100 that has been opened. Set in molding cavity 101. At this time, in the setting process of the present embodiment, the temperature sensitive element 10 and the pair of metal terminals 30 covered by the intermediate cover 50 in the previous covering process are also set in the molding cavity 101 of the mold 100 that has been opened. To do. In such a setting process, the pair of metal lead wires 20 and the pair of metal terminals 30 are set together with the temperature sensing element 10 in a direction Do perpendicular to the reference direction Db.

  In the injection step of S103 as the third step of the manufacturing method, as shown in FIG. 10, the mold 100 having the pair of metal lead wires 20 and the like set in the molding cavity 101 by the previous setting step is closed and Under the clamped state, the molten resin material is injected into the cavity 101. At this time, in the setting step of the present embodiment, only the gate 102 provided on the metal lead wire 20a side as one side among the both sides sandwiching the pair of metal lead wires 20 in the orthogonal direction Do in the molding die 100, Molten resin material is injected. In such a one-sided gate type molding, the injected molten resin material is obtained from the metal lead wire 20a as one side of the both sides sandwiching the pair of metal lead wires 20 in the orthogonal direction Do, and the metal lead as the other side. It flows toward the line 20b side.

  Here, in the injection step of this embodiment, in order to reinforce the resin casing 40 after molding, a fibrous filler is contained in the molten resin material. As a result, in the molding cavity 101 that complements the outer shape of the resin casing 40, the fiber orientation of the fibrous filler is easily along the reference direction Db around the metal lead wire 20 a on one side close to the gate 102. On the other hand, in such a molding cavity 101, the fiber orientation of the fibrous filler does not follow along the reference direction Db around the metal lead wire 20b on the other side far from the gate 102, for example, easily along the orthogonal direction Do.

  In the solidification step of S104 as the fourth stage of the manufacturing method, as shown in FIG. 11, the resin material is solidified by cooling of the molten resin material injected into the molding cavity 101 in the previous injection step, and the resin casing. 40 is formed. At this time, in the solidification process of the present embodiment, the circumference of the metal lead wire 20a on one side is smaller than the circumference of the metal lead wire 20b on the other side due to the difference in fiber orientation with respect to the fibrous filler in the injection process described above. A linear expansion coefficient αc is given in the reference direction Db. As a result, the temperature sensor 1 is completed.

(Function and effect)
The operational effects of the temperature sensor 1 described so far will be described below.

  In the temperature sensor 1, the intermediate cover 50 is interposed between the metal lead wire 20 inserted into the resin casing 40 by molding and the casing 40. Here, in the reference direction Db in which the extending portion 21 of the metal lead wire 20 extends, the linear expansion coefficient αm of the intermediate cover 50 is larger than that of the metal lead wire 20 and from the resin casing 40 due to the specific material forming the cover 50. Is also given small. Therefore, even under use in a high temperature environment, the thermal expansion amount of the intermediate cover 50 can be as close as possible to the thermal expansion amount of the metal lead wire 20 rather than the thermal expansion amount of the resin casing 40 in the reference direction Db. . Moreover, since the linear expansion coefficient difference Δα in the reference direction Db between the metal lead wire 20 and the intermediate cover 50 is set in a specific range, the stress σ generated in the metal lead wire 20 according to the set value is the metal lead wire. The tensile strength S1 is limited to be smaller than 20. As a result, in the metal lead wire 20, it is possible to suppress a situation in which the generated stress σ exceeds the tensile strength S 1 and causes disconnection, so that a high yield can be achieved.

  Further, in the metal lead wire 20 of the temperature sensor 1, the stress σ generated according to the linear expansion coefficient difference Δα in the reference direction Db with the intermediate cover 50 is the coefficient difference Δα, the Young's modulus Yl in the reference direction Db, and the operating temperature. It can be estimated by a multiplication value (Δα · Yl · ΔT) with the range ΔT. Therefore, by setting the linear expansion coefficient difference Δα in a specific range that satisfies the relationship Δα <Sl / (Yl · ΔT) in Equation 4, the generated stress σ is more reliably set than the tensile strength Sl in the metal lead wire 20. The wire breakage can be suppressed by limiting to a small value. Therefore, the reliability for achieving a high yield can be improved.

  Furthermore, according to the temperature sensor 1, the Young's modulus Ym of the intermediate cover 50 in the reference direction Db in which the extending portion 21 of the metal lead wire 20 extends is smaller than that of the metal lead wire 20 due to the specific material forming the cover 50 and It is given larger than the resin casing 40. Therefore, even under use in a high temperature environment, the tensile action in the reference direction Db by the resin casing 40 having a large thermal expansion amount is absorbed by the intermediate cover 50, and the metal lead wire 20 moves in the same direction Db by the action. Pulling can be reduced. According to this, since the stress σ generated in the metal lead wire 20 can be reduced and the disconnection can be suppressed, it is possible to contribute to the achievement of a high yield.

  Further, when the resin casing 40 is molded from a resin material containing a fibrous filler as in the temperature sensor 1, the linear expansion coefficient at each location of the resin casing 40 according to the formation position of the gate 102 in the molding die 100. αc may vary. Therefore, in the reference direction Db, as long as the linear expansion coefficient difference Δα with the metal lead wire 20 having a smaller linear expansion coefficient αl is within a specific range with respect to the linear expansion coefficient αm of the intermediate cover 50 formed of the specific material, the resin It is smaller than the minimum linear expansion coefficient αc of the casing 40. According to this, since the thermal expansion amount of the intermediate cover 50 surely approaches the thermal expansion amount of the metal lead wire 20 rather than the thermal expansion amount at an arbitrary location of the resin casing 40, the generated stress σ is generated in the lead wire 20. Is limited to be smaller than the tensile strength S1 and disconnection can be suppressed. Therefore, it is possible to contribute to achieving a high yield.

  Further, in the manufacturing method of the temperature sensor 1, the pair of metal lead wires 20 covered with the intermediate cover 50 are arranged in the direction Do perpendicular to the reference direction Db, and together with the temperature sensing element 10, the molding cavity 101 of the molding die 100. Set in. In such a molding die 100, from the gate 102 provided on one side of both sides sandwiching the set pair of metal lead wires 20 in the orthogonal direction Do, toward one side and the other side of the both sides, The molten resin material is injected into the molding cavity 101. As a result, in the resin casing 40 formed by solidification of the molten resin material injected into the molding cavity 101, the metal on the other side far from the gate 102 around the metal lead wire 20 a on one side near the gate 102. A linear expansion coefficient αc higher than that around the lead wire 20b is given in the reference direction Db. This is because the molten resin material flows along the reference direction Db around the metal lead wire 20a on one side, but does not follow the same direction Db around the metal lead wire 20b on the other side. For example, when the molten resin material flows along the orthogonal direction Do, a difference occurs in the fiber orientation of the fibrous filler.

  However, in the reference direction Db of the temperature sensor 1 manufactured according to the present embodiment, the linear expansion coefficient αm of the intermediate cover 50 is linearly expanded with the linear expansion coefficient αl of each metal lead wire 20 (20a, 20b) smaller than that. As long as the coefficient difference Δα is within the specific range, the coefficient is given smaller than the minimum linear expansion coefficient αc of the resin casing 40. According to this, since the amount of thermal expansion of the intermediate cover 50 surely approaches the amount of thermal expansion of each metal lead wire 20 rather than the amount of thermal expansion at an arbitrary location of the resin casing 40, The generated stress σ is limited to be smaller than the tensile strength Sl, and disconnection can be suppressed. Therefore, it can contribute to the achievement of a high yield.

(Other embodiments)
Although one embodiment of the present invention has been described above, the present invention is not construed as being limited to the embodiment, and can be applied to various embodiments without departing from the gist of the present invention. it can.

  Specifically, as a first modification, for example, the temperature sensor 1 may be used in a vehicle other than a vehicle such as an outside air temperature sensing around a bridge (for an outside air temperature display for alerting winter freezing).

  As a second modification, the Young's modulus Ym of the intermediate cover 50 may be set smaller than the Young's modulus Yc of the resin casing 40. Moreover, as the modification 3, the specific material which forms the resin casing 40 does not need to contain a fibrous filler. Furthermore, as a fourth modification, the specific material forming the intermediate cover 50 may not contain a fibrous filler.

  As a fifth modification, the metal lead wire 20 may be configured only from the substantially extending portion 21 without providing the inclined portion 22. Further, as a sixth modified example, the metal lead wire 20 may be electrically connected to an external circuit without providing the metal terminal 30.

  As a modified example 7, as shown in FIG. 12, a molten resin material is injected into a molding cavity 101 from gates 102 provided on both sides sandwiching a pair of metal lead wires 20 in the orthogonal direction Do, thereby forming a resin casing. 40 may be molded. Further, as the eighth modification, the resin casing 40 may be molded by the molding die 100 provided with the gate 102 in a positional relationship different from that of the above-described embodiment and the seventh modification.

  As a modification 9, the temperature sensitive element 10 may be exposed in the molding cavity 101 in the setting step S102 without being covered with the intermediate cover 50 in the covering step S101. Further, as a tenth modification, the metal terminal 30 may not be covered with the intermediate cover 50 in the covering step S101 and may be exposed in the molding cavity 101 in the setting step S102. Furthermore, as a modified example 11, the intermediate cover 50 and the resin casing 40 may be sequentially formed by double molding of a resin material.

DESCRIPTION OF SYMBOLS 1 Temperature sensor, 10 Temperature sensing element, 20, 20a, 20b Metal lead wire, 21 Extension part, 22 Inclination part, 30 Metal terminal, 40 Resin casing, 50 Intermediate cover, 100 Molding die, 101 Molding cavity, 102 Gate , Db reference direction, Do orthogonal direction, Sl tensile strength, Th maximum temperature, Tl minimum temperature, Yc, Yl, Ym Young's modulus, αc, αl, αm linear expansion coefficient, Δα linear expansion coefficient difference, ΔT working temperature range, σ stress

Claims (5)

A temperature sensing element (10) for sensing temperature;
A metal lead wire (20, 20a, 20b) that is formed of a metal material, has an extending portion (21) extending along the reference direction (Db), and is electrically connected to the temperature sensitive element;
A resin casing (40) formed of a resin material and inserted with the metal lead wire by molding;
An intermediate cover (50) formed from a specific material that gives a linear expansion coefficient larger than the metal lead wire and smaller than the resin casing in the reference direction and interposed between the resin casing and the metal lead wire; With
The difference in linear expansion coefficient in the reference direction between the metal lead wire and the intermediate cover is a specification that limits the stress generated in the metal lead wire to be smaller than the tensile strength of the metal lead wire according to the difference in linear expansion coefficient A temperature sensor characterized by being set to a range. Define the linear expansion coefficient difference in the reference direction as Δα,
The tensile strength of the metal lead wire is defined as Sl,
The Young's modulus in the reference direction of the metal lead wire is defined as Yl,
If the assumed operating temperature range is defined as ΔT,
2. The temperature sensor according to claim 1, wherein the linear expansion coefficient difference is set in the specific range that satisfies a relationship of Δα <Sl / (Yl · ΔT).   3. The temperature sensor according to claim 1, wherein the intermediate cover is formed from the specific material that gives Young's modulus smaller than the metal lead wire and larger than the resin casing in the reference direction. 4. . The resin casing is formed from the resin material containing a fibrous filler by the molding,
The temperature sensor according to claim 1, wherein a linear expansion coefficient of the intermediate cover in the reference direction is smaller than a minimum linear expansion coefficient of the resin casing. A method for manufacturing the temperature sensor according to claim 4, comprising:
A covering step (S101) for covering the pair of metal lead wires with the intermediate cover;
A pair of the metal lead wires covered with the intermediate cover in the covering step are arranged in a direction orthogonal to the reference direction (Do), and together with the temperature sensitive element, a molding cavity (101) of the molding die (100). ) In the setting step (S102),
In the molding die, from the gate (102) provided on one side of both sides sandwiching the pair of metal lead wires set in the setting step in the orthogonal direction, the one side and the other of the both sides An injection step (S103) for injecting the molten resin material into the molding cavity toward the side;
A temperature sensor manufacturing method comprising: a solidifying step (S104) of forming the resin casing by solidifying the resin material injected into the molding cavity in the injection step.

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