Temperature sensor and method of manufacturing the same

Abstract

The temperature sensor (1) of the present invention comprises a sensor element (10) and a resin coating (20) extending in a predetermined direction (L). The coating (20) comprises a first coating (30) that covers a portion of the thermosensitive element (11), a pair of electrodes (11a, 11a), and a pair of conductive wires (12, 12), and a second coating (40) that is laminated on the first coating (30) and covers a portion of the first coating (30). The first coating (30) is The heat-sensing element (11), the pair of electrodes (11a, 11a) and a portion of the pair of conductive wires (12, 12) are provided inside the second covering body (40), and a pair of conductive wire covering portions (30B, 30B) are provided outside the second covering body (40) and individually cover a portion of the pair of conductive wires (12, 12), and the inner covering portion (30A) and the conductive wire covering portions (30B, 30B) are integrally formed.

Description

[Technical Field]

[0001] The present invention relates to a temperature sensor and a method for manufacturing the same. [Background technology]

[0002] Temperature sensors equipped with a thermosensitive element such as a thermistor are widely used. Among these, there are temperature sensors in which the thermosensitive element is sealed with a resin coating to protect it from the surrounding environment. Temperature sensors are used for a variety of purposes, and there is a demand for thin temperature sensors with small dimensions in the thickness direction. Thin temperature sensors are used, for example, by inserting them into narrow spaces.

[0003] A known example of a thin temperature sensor is the temperature sensor described in Patent Document 1. This temperature sensor includes a thermal element including a thermal sensor, a lead wire at one end electrically connected to the thermal sensor, and a sealing body made of an insulating material that covers part of the lead wire and the thermal sensor, a lead wire electrically connected to the other end of the lead wire, and a resin coating with a rectangular cross section that covers part of the lead wire and the thermal sensor. In the short direction, the dimensions of the area covering the thermal sensor are set smaller than the dimensions of the area covering the lead wire. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7058377 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a demand in the medical field for temperature sensors that are waterproof and have a smaller diameter, such as in endoscopes.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a temperature sensor that is water-resistant and has a smaller diameter. [Means for solving the problem]

[0007] The temperature sensor of the present invention comprises: a sensor element having a pair of electrodes, a thermosensitive body whose resistance changes in response to a change in temperature, and a pair of conductive wires, each of which is electrically connected at one end to the pair of electrodes; a resin covering that covers at least the heat sensitive element and one end of the pair of conductive wires and extends in a predetermined direction; The covering body is a first covering that covers the heat-sensitive element, the pair of electrodes, and a portion of the pair of conductive wires; a second covering body laminated on the first covering body and covering a part of the first covering body; The first covering body is an inner covering portion that covers the heat-sensing element, the pair of electrodes, and a portion of the pair of conductive wires inside the second covering portion; a pair of conductive wire covering portions that individually cover portions of the pair of conductive wires on the outside of the second covering body, The inner covering and the conductive wire covering are integrally formed.

[0008] The pair of conductive wire coating portions preferably include: It consists of a tubular insulator attached to each of a pair of conductive wires.

[0009] The pair of conductive wire coating portions preferably include: The second cover has a fused portion that is integrated by fusion in a predetermined area exposed from the second cover.

[0010] Preferably, The sensor element includes a pair of electrodes, a heat-sensitive body, and a sealing body that covers a portion of a pair of conductive wires connected to the heat-sensitive body; The second covering body extends beyond the sealing body in one predetermined direction.

[0011] The gap in the second covering body is preferably provided with a filler that seals the opening on one side.

[0012] Preferably, The inner resin material constituting the first coating is The melting point is lower than that of the outer resin material that constitutes the second coating.

[0013] Preferably, the first coating is made of PFA (perfluoroalkoxyalkane); The second covering is made of PTFE (polytetrafluoroethylene).

[0014] The jacket is preferably cylindrical in shape.

[0015] According to the present invention, A method for manufacturing a temperature sensor including a sensor element having a pair of conductive wires electrically connected to a heat sensor, and a covering made of a resin material that individually covers the heat sensor and the pair of conductive wires, comprising: Inserting a pair of conductive wires of the sensor element into a pair of first insulating tubes, respectively; a step of inserting the heat-sensor and a predetermined area of ​​the first insulating tube from the heat-sensor side into a second insulating tube having heat shrinkability; and heating the second insulating tube from its surroundings to melt and integrate the second insulating tube with the overlapping first insulating tube, and shrinking the second insulating tube. [Effects of the Invention]

[0016] The first coating of the temperature sensor of the present invention includes an inner coating that covers the thermosensitive element, the pair of electrodes, and a portion of the pair of conductive wires inside the second coating, and a pair of conductive wire coatings that individually cover a portion of the pair of conductive wires outside the second coating, the inner coating and the conductive wire coatings being integrally formed, thereby providing a water-resistant temperature sensor with a smaller diameter. [Brief explanation of the drawings]

[0017] [Figure 1] 1A and 1B are a side view and a partial cross-sectional side view showing a temperature sensor according to an embodiment; [Figure 2] 1 is a diagram showing a sensor element 10 applied to a temperature sensor according to an embodiment. [Figure 3] 2A and 2B are cross-sectional views taken along arrows IIA-IIA, IIB-IIB, IIC-IIC, and IID-IID in FIG. 1. [Figure 4] 1A to 1C are diagrams illustrating a manufacturing procedure for a temperature sensor according to an embodiment. [Figure 5] 5 is a diagram illustrating a manufacturing procedure for the temperature sensor according to the embodiment, following FIG. 4. [Figure 6] FIG. 10 is a diagram showing a temperature sensor according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] [Temperature sensor 1 configuration: Figure 1] The temperature sensor 1 includes a sensor element 10, which will be described later with reference to FIG. 2, and a coating 20 made of a resin material that seals the sensor element 10. As shown in the right diagram, the coating 20 is made up of a first coating 30 and a second coating 40 that is laminated on the outside of the first coating 30. The first coating 30 is configured to individually cover the front (F) side of the sensor element 10 and a pair of conductive wires 12, 12, which will be described later. The second coating 40 is configured to cover a portion of the front (F) side of the first coating 30.

[0020] Hereinafter, the longitudinal direction L and width direction W of the temperature sensor 1 are defined as shown in each drawing. In addition, in the temperature sensor 1, the side of the longitudinal direction L on which the heat sensor 11 is provided is defined as the front or front side (F), and the opposite side is defined as the rear or rear side (R). These definitions of front and rear have relative meanings.

[0021] [Sensor element 10: Figure 2] The sensor element 10 comprises a thermosensitive body 11 that detects the temperature of an object to be detected (not shown), a pair of conductive wires 12, 12 whose ends 12a, 12a at the front (F) side in the longitudinal direction L are electrically connected to the thermosensitive body 11, and a sealing body 13 made of an insulating material that seals a portion of the pair of conductive wires 12, 12 and the entire thermosensitive body 11.

[0022] [Thermal sensor 11: Figure 2] The heat sensitive element 11 is made of a metal oxide or metal that has the property of changing its electrical resistance value with a change in temperature. Thermistors (Thermally Sensitive Resistors) are preferably used as the metal oxides, typically NTC thermistors (Negative Temperature Coefficient Thermistors) with a negative temperature coefficient, and platinum (e.g., Pt100; JIS-C1604) is preferably used as the metal. The heat sensitive element 11 is formed in a rectangular parallelepiped shape, and has electrodes 11a, 11a provided on two opposing surfaces.

[0023] [Conductive wire 12, 12: Figure 2] The pair of conductive wires 12, 12 have their front (F) ends 12a, 12a electrically connected to the electrodes 11a, 11a of the heat-sensitive element 11, respectively, and their rear (R) ends 12b, 12b are pulled out toward the rear (R) from the sealing body 13 described later. The conductive wire 12 is used to pass a constant current through the heat-sensing element 11. A metal material with high electrical conductivity, typically copper, is used for the conductive wire 12, and Dumet wire is preferably used. Dumet wire is a composite wire clad with an inner layer made of an iron-nickel alloy and an outer layer made of copper. While passing a current through the pair of conductive wires 12, 12, the voltage between a pair of electrodes (not shown) of the heat-sensing element 11 is measured, and the resistance value is calculated using Ohm's law (E=IR) to detect the temperature.

[0024] [Sealant 13: Figure 2] The seal 13 is provided to surround the heat sensor 11 and seal it airtight to prevent chemical and physical changes in the heat sensor 11. For example, glass is used as the seal 13. In particular, when a Dumet wire is used for the conductive wire 12, it is preferable to use glass for the seal 13 because the linear expansion coefficients of iron-nickel alloy and glass are similar. Note that in the present invention, a material other than glass, such as a resin material, may be used for the seal 13, and the seal 13 may be omitted depending on the environment in which the temperature sensor 1 is used. The shape of the sealing body 13 is, for example, a spindle shape.

[0025] [Covering body 20: Figures 1 and 3] The cover 20 is intended to improve water resistance, dust resistance, and insulation properties by sealing the sensor element 10. The cover 20 is composed of a first cover 30 and a second cover 40.

[0026] The first coating 30 and the second coating 40 are made of an electrically insulating resin material. Fluororesin is preferably used for the first coating 30 and the second coating 40. This is because fluororesin has excellent water repellency, chemical resistance, and electrical insulation properties. Examples of fluororesin include PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), and FEP (perfluoroethylene-propene copolymer). The melting points of PTFE, PFA, and FEP are 327°C, 310°C, and 260°C, respectively, and are selected appropriately depending on the heating temperature used to fuse the resin material constituting the first coating 30. For example, when PFA, which has a relatively low melting point, is used for the first coating 30, it is preferable to use PTFE, which has a relatively high melting point, for the second coating 40. Note that in this embodiment, a case is illustrated in which PFA is used for the first coating 30 and PTFE is used for the second coating 40.

[0027] [First covering 30: see Figures 1, 3, and 4] 1, the first coating 30 is composed of an inner coating 30A extending in the longitudinal direction L and a pair of conductive wire coatings 30B, 30B formed continuously with the inner coating 30A on the rear (R) side and individually covering the pair of conductive wires 12, 12. The inner coating 30A is covered by the second coating 40, but the conductive wire coatings 30B, 30B are exposed to the outside of the second coating 40.

[0028] [Inner covering portion 30A: Figures 1 and 3] The inner covering portion 30A airtightly seals the sealing body 13 and the conductive wires 12, 12 at the front (F) side in the longitudinal direction L. The inner covering portion 30A is formed in a substantially cylindrical shape. In addition to covering and sealing the sealing body 13 and the conductive wires 12, 12 from the outside in the width direction W, the inner covering portion 30A also fills the gap between the conductive wires 12, 12, as shown in the IIC-IIC cross-sectional view of FIG. 3 . Therefore, the inner covering portion 30A not only electrically insulates the pair of conductive wires 12, 12 but also maintains a distance between them. Note that, although the inner covering portion 30A in this embodiment is described as having a substantially cylindrical shape, the present invention is not limited thereto. The inner covering portion 30A may be formed in any shape, such as a rectangular prism or a triangular prism. An end 30a on the front (F) side in the longitudinal direction L of the inner covering portion 30A coincides with a contact line CL with the sealing body 13 of the sensor element 10, which will be described later, and an end 30b on the rear (R) side coincides with an end 40b on the rear (R) side of the second covering portion 40. A pair of conductive wire covering portions 30B, 30B extend rearward (R) from the end 30b on the rear (R) side of the inner covering portion 30A. As shown in the figure, the contact line CL refers to a line segment where the maximum diameter portion of the sealing body 13 and the inner periphery of the second covering portion 40 meet.

[0029] [Conductive wire covering parts 30B, 30B: Figures 1 and 3] The pair of conductive wire covering portions 30B, 30B are airtightly sealed except for the rear (R) side of the pair of conductive wires 12, 12 in the longitudinal direction L, thereby preventing moisture and other contaminants from penetrating into the sensor element 10 and ensuring insulation between the two wires and between the conductive wire 12 and the outside. In this embodiment, the conductive wire covering portions 30B, 30B are made of the same fluororesin material as the inner covering portion 30A. As shown in the IID-IID cross-sectional views of FIGS. 1 and 3, the pair of conductive wire covering portions 30B, 30B are formed in a tubular shape extending in the longitudinal direction L. The pair of conductive wire covering portions 30B, 30B are arranged side by side in the width direction W, and the front (F) end portion 30c is seamlessly connected to the rear (R) end portion 30b of the inner covering portion 30A. The pair of conductive wire covering portions 30B, 30B contact each other at the center 30bc in the width direction W of the end portion 30b of the inner covering portion 30A. Note that, in the present embodiment, the pair of conductive wire covering portions 30B, 30B contact each other at the center 30bc of the end portion 30b of the inner covering portion 30A, but the present invention is not limited to this. The pair of conductive wire covering portions 30B, 30B do not necessarily need to contact each other at the center 30bc of the end portion 30b, and a small gap may be formed between them. Furthermore, the pair of conductive wire coating portions 30B, 30B exposed from the second coating 40 are in contact with each other but are not connected, for example, by fusion. That is, in the temperature sensor 1, the pair of conductive wire coating portions 30B, 30B are independent.

[0030] The pair of conductive wire covering portions 30B, 30B each cover a predetermined range from the end 30b of the inner covering portion 30A to the rear (R) side of the ends 12a, 12a of the pair of conductive wires 12, 12. The ends 12b, 12b of the conductive wires 12, 12 are exposed from each end (lower end in the drawing) on ​​the rear (R) side in the longitudinal direction L of the pair of conductive wire covering portions 30B, 30B, and the ends 12b, 12b of the pair of conductive wires 12, 12 are connected to a downstream electric circuit (not shown).

[0031] The longitudinal dimension L of the pair of conductive wire coatings 30B, 30B can be set to any dimension as needed, depending on the usage environment of the sensor element of the present invention, etc. For example, the pair of conductive wire coatings 30B, 30B may be set to the same length, or one conductive wire coating 30B may be set to be longer than the other conductive wire coating 30B. Furthermore, if it is possible to prevent moisture from entering the temperature sensor and ensure insulation between the pair of conductive wires 12, 12 and the outside, the conductive wire coating 30B may be provided on only one of the conductive wires 12. Furthermore, in this embodiment, the pair of conductive wire coatings 30B, 30B are described as having a circular tubular outer periphery, but the outer shape can be set as desired. For example, like the shape of the inner coating 30A, the shape of the conductive wire coating 30B can be any shape, such as a rectangular prism or a triangular prism.

[0032] [Second covering 40: Figures 1 and 3] The second coating 40 is provided outside the first coating 30 in the width direction W, is formed in a cylindrical shape extending in the longitudinal direction L, and as shown in the IIB-IIB cross-sectional view, is in direct contact with the outer periphery of the sealing body 13 at a contact line CL. Here, the contact line CL refers to the contact portion between the inner periphery of the second coating 40 and the outer periphery of the sealing body 13 of the sensor element 10. As described above, since the sealing body 13 is formed in a spindle shape, the contact line CL is a collection of contact points with the second coating 40 that are continuous in the outer periphery direction of the sealing body 13.

[0033] The dimension of the second covering 40 in the longitudinal direction L is set to be larger than the dimension of the inner covering portion 30A of the first covering 30 in the longitudinal direction L. As shown in FIG. 1 , the end (tip) 40a on the front (F) side of the second covering 40 in the longitudinal direction L is located forward (F) of the contact line CL in the longitudinal direction L, and the end 40b on the rear (R) side is formed at the same position as the rear (R) end 30b of the inner covering portion 30A. Therefore, as shown in the IIA-IIA cross-sectional view of FIG. 3 , a gap G having an opening 40c on the front (F) side is formed inside the front (F) side of the second covering 40, i.e., between the contact line CL between the second covering 40 and the sealing body 13 and the tip 40a, and the end 40a side of the second covering 40 protrudes forward (F) beyond the tip 13a of the sealing body 13. This configuration can prevent the sealing body 13 from being scratched or damaged by hitting an external object during manufacturing of the temperature sensor or during installation in a device.

[0034] It is preferable that the second coating 40 contacts the outer peripheral surface of the sealing body 13 with pressure at the contact line CL. Therefore, as will be described later, a heat-shrinkable tube is used for forming the second coating 40, the dimension in the width direction W after shrinkage being smaller than the dimension in the width direction W of the sealing body 13. By applying pressure from the second coating 40 to the sealing body 13 in this way, the second coating 40 and the sealing body 13 can be tightly adhered to each other. As a result, the coating 20 can reduce the penetration of liquids such as moisture from the tip 40a side at its front (F) to the rear (R) of the contact line CL.

[0035] The dimension of the second coating 40 in the width direction W at the contact line CL is set larger than those at the front (F) and rear (R) of the contact line CL. As described below, since the second coating 40 is formed by shrinking a heat-shrinkable tube, the dimension in the width direction W after heating is approximately uniformly smaller than that of the original heat-shrinkable tube. However, due to the presence of the sealing body 13 of the sensor element 10 inside, the thermal shrinkage of the heat-shrinkable tube at the contact line CL is restricted compared to the front (F) and rear (R). On the other hand, in the portion other than the position contacting the sealing body 13, i.e., the position where the inner covering portion 30A and the gap G are present, there is no sealing body 13 to restrict the shrinkage, so the heat-shrinkable tube shrinks more than the portion where the sealing body 13 is present. As a result, as shown in FIG. 1 , the dimension of the coating 20 in the width direction W at the inner covering portion 30A and the gap G of the first coating 30 is smaller. As described above, the maximum dimension in the width direction W of the second coating 40 is the dimension in the width direction W at the contact line CL. In other words, the second cover 40 is made thinner to the dimension of the contact line CL in the width direction W while maintaining waterproofing, thereby realizing a thinner temperature sensor 1.

[0036] In the present embodiment, the covering 20 is described with an example in which the dimensions of the inner covering portion 30A of the first covering 30 and the width direction W at the gap G are smaller than the portion where the sealing body 13 is present. However, the present invention is not limited to this. The second covering 40 does not need to abut the sealing body 13 as long as the molten PFA (described below) formed during heating is prevented from flowing out from the front (F) in the longitudinal direction L of the heat-shrinkable tube. This is because the inner covering portion 30A of the first covering 30 and the sealing body 13 can prevent water and the like from entering the interior through the opening 40c of the gap G. In this case, the dimension of the width direction W of the second covering 40 can be set to be equal to the front (F) and rear (R) of the contact line CL.

[0037] [Method of manufacturing temperature sensor 1: Figures 4 and 5] Next, a manufacturing procedure for the temperature sensor 1 will be described with reference to Figures 4 and 5. Note that the manufacturing method described below is based on the premise that the sensor element 10 has already been manufactured. [STEP A: Figure 4] The sensor element 10 and two first insulating tubes 50, 50 that will form the first coating 30 after manufacturing are prepared. The conductive wire 12 of the sensor element 10 is made of, for example, a Dumet wire with a diameter of 0.15 mm, and the first insulating tube 50 is made of, for example, PFA and has an inner diameter that allows the conductive wire 12 to be inserted without difficulty.

[0038] [STEP B: Figure 4] The conductive wires 12 are inserted from the rear (R) end portions 12b through the openings at the tips 50a in the longitudinal direction L of the two prepared first insulating tubes 50. The two first insulating tubes 50 are pushed in until one end portion (tip) 50a abuts against the sealing body 13. Hereinafter, the sensor element 10 with the two first insulating tubes 50 inserted therethrough is referred to as sensor element 10A. Next, a second insulating tube 51 is prepared, which will form the second covering body 40 after manufacturing. As an example, a PTFE tube is used for the second insulating tube 51. The inner diameter of the second insulating tube 51 is set to be equal to or slightly larger than the outer diameter of the sealing body 13.

[0039] [STEP C: Figure 5] Next, the sensor element 10A is inserted into the second insulating tube 51. The sensor element 10A is inserted from the front (F) side in the longitudinal direction L of the sensor element 10A, i.e., the tip 13a side of the seal 13 of the sensor element 10A, through the opening on the end (rear end) 51b side on the rear (R) side in the longitudinal direction L of the second insulating tube 51. Note that, in this step C, the case where the sensor element 10A is inserted from the opening on the rear end 51b side on the rear (R) side of the second insulating tube 51 is illustrated, but it may also be inserted from the opening on the end (tip) 51a side on the front (F) side in the longitudinal direction L of the second insulating tube 51. Here, the position of the sealing body 13 of the sensor element 10A in the longitudinal direction L within the second insulating tube 51 will be described. The position of the sealing body 13 in the longitudinal direction L is set so that after the second insulating tube 51 is thermally shrunk, the tip 13a of the sealing body 13 is forward of the tip 40a of the covering body 20 (second covering body 40), that is, at a position where the sealing body 13 is not exposed to the outside of the covering body 20. In other words, the sealing body 13 is positioned so that the tip 51a of the second insulating tube 51 protrudes forward (F) beyond the tip 13a of the sealing body 13. When the sensor element 10A is disposed in the second insulating tube 51 as described above, a gap G is provided inside the second insulating tube 51 in the front (F) of the sealing body 13, and a portion of the first insulating tubes 50, 50 on the front end 50a side overlaps with the second insulating tube 51, and the rear (R) ends 50b, 50b side are exposed from an opening on the rear end 51b side of the second insulating tube 51. Hereinafter, this portion of the first insulating tubes 50, 50 overlapping with the second insulating tube 51 will be referred to as an overlapping portion 50C.

[0040] [STEP D: Figure 5] While fixing the second insulating tube 51 so that it does not come off or shift from the sensor element 10A, the second insulating tube 51 is heated from the width direction W side. This heating is performed at a temperature that melts PFA but does not melt PTFE, causing thermal shrinkage. Specifically, since the melting point of PFA is 310°C and the melting point of PTFE is 327°C, the heating temperature HT is selected from the range of the following formula (1). 310℃ < HT < 327℃ Equation (1)

[0041] When heated for a predetermined time at a temperature within the range of formula (1) above, the overlapping portion 50C of the first insulating tubes 50, 50 melts inside the second insulating tube 51, and the second insulating tube 51 shrinks in the width direction W. Hereinafter, the PFA formed by melting this overlapping portion 50C is referred to as molten PFA 30C2. As heating continues, the second insulating tube 51 shrinks, and the second insulating tube 51 comes into contact with the sealing body 13 of the sensor element 10A, forming a contact line CL. At this contact line CL, there is no gap between the second insulating tube 51 and the sealing body 13 of the sensor element 10A, so the molten PFA 30C2 is blocked at this contact line CL and prevented from moving forward (F). When further heated, the second insulating tube 51 further shrinks in the width direction W, and only the portion of the second insulating tube 51 that comes into contact with the sealing body 13 of the sensor element 10 bends to match the outer diameter of the sealing body 13, deforming into an external shape similar to that of the temperature sensor 1 shown in Figure 1. After the second insulating tube 51 has been sufficiently heated, the heating is stopped, and the molten PFA 30C2 dissipates heat and solidifies. The molten PFA 30C2 then solidifies and integrates from the contact line CL to the rear end 51b on the rear (R) side of the second insulating tube 51, forming the inner covering portion 30A. Meanwhile, at the rear (R) side end 30b of this inner covering portion 30A, the first insulating tubes 50, 50 contact each other at the center 30bc, and a pair of conductive wire covering portions 30B, 30B are formed that are continuous with the end 30b and extend rearward (R). The molten PFA 30C2 may be solidified by forced cooling, such as by spraying a cooling medium after heating, or by natural heat dissipation. By carrying out the above steps, the temperature sensor 1 shown in FIG. 1 is fabricated.

[0042] [Effects of Temperature Sensor 1] The effects achieved by the temperature sensor 1 will be described below. [First effect]

[0043] The temperature sensor 1 is provided with two coatings, a first coating 30 and a second coating 40, but the second coating 40 is in direct contact with the sealing body 13, which has the largest dimension in the width direction W, in the sensor element 10. In other words, the temperature sensor 1 is provided with two coating layers, the first coating 30 and the second coating 40, in the region where the first coating 30 is provided, but only the second coating 40 is provided in front (F) of the contact line CL of the sealing body 13, so the dimension in the width direction W can be minimized.

[0044] [Second effect] The covering 20 of the temperature sensor 1 is heated and cooled with the first insulating tubes 50, 50, the predecessor of the first covering 30, inside the second insulating tube 51 made of PTFE, the predecessor of the second covering 40. This heating and cooling causes the first insulating tubes 50, 50 to melt and solidify, forming the inner covering portion 30A of the first covering 30. During this melting and solidification process, the second insulating tube 51 made of PTFE shrinks in the width direction W. As a result, pressure is applied from the second covering 40 to the sealing body 13. This allows the second covering 40 and the sealing body 13 to be tightly adhered to each other, improving water resistance.

[0045] [Third effect] In the temperature sensor 1, a portion of the first insulating tube 50, which is the precursor, melts and solidifies to form the inner covering 30A. Meanwhile, the first insulating tube 50 remains behind (R) the inner covering 30A to form the conductive wire coverings 30B. These conductive wire coverings 30B surround the conductive wires 12. This allows the inner covering 30A and the pair of conductive wire coverings 30B to be integrally formed. This eliminates the need to prepare a separate member for forming the first covering 30, thereby improving the productivity of the temperature sensor 1. Furthermore, because the first covering 30 integrally forms the inner covering 30A and the conductive wire coverings 30B in the longitudinal direction L, no insulating tube is present inside the covering 20, eliminating any gaps between the inner covering 30A and the insulating tube. As a result, the width W dimension can be reduced, achieving compactness while maintaining water resistance.

[0046] [Fourth effect] According to the temperature sensor 1, the inside of the second covering body 40 in front (F) of the sealing body 13 that covers the heat sensitive element 11 is made into a gap G, so the tip 40a side of the second covering body 40 protrudes forward (F) beyond the tip 13a of the sealing body 13. This configuration prevents the sealing body 13 from being scratched or damaged by hitting an external object during manufacturing of the temperature sensor or installation work into a device.

[0047] Although the preferred temperature sensor 1 of the present invention has been described above, the present invention can be modified in several ways, as will be explained below.

[0048] [Variation 1: Figure 6] In the temperature sensor 1, the conductive wire coating portions 30B, 30B exposed from the second coating 40 are independent and not connected to each other, but the present invention is not limited to this. That is, the conductive wire coating portions 30B, 30B can be joined by the fusion portion 14 in a predetermined area exposed from the second coating 40.

[0049] In this modified example 1, a case will be described in which a fused portion 14 is provided in the first coating 30. Note that parts common to the temperature sensor 1 shown in the above embodiment are given the same numbers as in Figure 1, and detailed descriptions will be omitted. The temperature sensor 2 shown in this modified example 1 differs from the temperature sensor 1 in that a fused portion 14 is formed on the rear (R) side of the inner covering 30A in the longitudinal direction L, protruding further rearward (R) than the rear (R) end 40b of the second covering 40. The fused portion 14 is formed integrally with the inner covering 30A. Specifically, the fused portion 14 is formed by melting a predetermined area on the front (F) sides of the pair of conductive wire coverings 30B, 30B from the end 40b of the second covering 40 to the rear. That is, in the temperature sensor 2 shown in modified example 1, the rear (R) end 30b of the inner covering 30A is exposed from the end 40b of the second covering 40, and this exposed portion is equivalent to forming the fused portion 14. If the fused portion 14 is provided, it can be inferred that the first insulating tubes 50, 50 are melted together and solidified inside the second covering 40 to form the inner covering portion 30A.

[0050] [Modification 2: Sealing of gap G: see Figures 1 and 6] In the temperature sensors 1 and 2, a gap G is provided in the second coating 40 in front (F) of the sealing body 13, but the present invention is not limited to this. This gap G may be filled with the same resin material as the first coating 30. By filling the gap G with a resin material in this way, the gap G on the front (F) side in the longitudinal direction L of the temperature sensors 1 and 2 is blocked, thereby improving the airtightness, dustproofness, water resistance, and weather resistance. [Explanation of symbols]

[0051] 1,2 Temperature sensor 10,10A sensor element 11 Heat-sensitive element 12 Conductive wire 13 Sealing body 14 Fusion part 20 Covering 30 First covering 30A Inner coating 30B Conductive wire sheathing part 40 Second covering 50 First insulating tube 51 Second insulating tube CL contact line G void L Longitudinal direction W width direction Before F After R

Claims

1. a sensor element having a pair of electrodes, a thermosensitive body whose resistance changes in response to a change in temperature, and a pair of conductive wires, one end of which is electrically connected to the pair of electrodes; a resin coating that covers at least the heat sensitive element and one end of the pair of conductive wires and extends in a predetermined direction; The coating body is a first coating that covers the heat-sensitive element, the pair of electrodes, and a portion of the pair of conductive wires; a second covering body laminated on the first covering body and covering a part of the first covering body, The first covering body is an inner covering portion that covers the heat-sensing element, the pair of electrodes, and a portion of the pair of conductive wires inside the second covering portion; a pair of conductive wire coating portions that individually cover portions of the pair of conductive wires on the outside of the second coating body, The inner covering portion and the conductive wire covering portion are integrally formed. Temperature sensor.

2. The pair of conductive wire covering portions are a tubular insulator provided on each of the pair of conductive wires; The temperature sensor of claim 1 .

3. The pair of conductive wire covering portions are a fusion portion that is integrated by fusion in a predetermined area exposed from the second cover, The temperature sensor according to claim 1 or 2.

4. the sensor element includes a sealing body that covers the pair of electrodes, the thermosensitive body, and a portion of the pair of conductive wires connected to the thermosensitive body; the second covering body extends further in one of the predetermined directions than the sealing body, The inside of the extended second covering body is an air gap. The temperature sensor according to claim 2 .

5. The gap of the second covering body is provided with a filler that seals the opening on one side. The temperature sensor according to claim 4.

6. The inner resin material constituting the first covering body is a melting point lower than that of the outer resin material constituting the second coating; The temperature sensor of claim 1 .

7. the first coating is made of PFA (perfluoroalkoxyalkane), The second covering is made of PTFE (polytetrafluoroethylene). The temperature sensor according to claim 6.

8. The covering body is formed in a cylindrical shape. The temperature sensor according to claim 4.

9. A method for manufacturing a temperature sensor including a sensor element having a pair of conductive wires electrically connected to a heat sensor, the sensor element including a covering made of a resin material that individually covers the heat sensor and the pair of conductive wires, the method comprising: inserting the pair of conductive wires of the sensor element into a pair of first insulating tubes; a step of inserting the heat-sensor and a predetermined area of ​​the first insulating tube from the heat-sensor side into a second insulating tube having heat shrinkability; and heating the second insulating tube from its periphery to melt and integrate the second insulating tube and the overlapping first insulating tube, and shrink the second insulating tube. A method for manufacturing a temperature sensor.

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