CN110715751B - Temperature sensor - Google Patents

Temperature sensor Download PDF

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Publication number
CN110715751B
CN110715751B CN201910630720.9A CN201910630720A CN110715751B CN 110715751 B CN110715751 B CN 110715751B CN 201910630720 A CN201910630720 A CN 201910630720A CN 110715751 B CN110715751 B CN 110715751B
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CN
China
Prior art keywords
element electrode
electrode wire
conductive
temperature sensor
conductive tube
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Application number
CN201910630720.9A
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Chinese (zh)
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CN110715751A (en
Inventor
大矢俊哉
三岛大辅
大矢诚二
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Niterra Co Ltd
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NGK Spark Plug Co Ltd
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Priority claimed from JP2019030513A external-priority patent/JP2020016633A/en
Application filed by NGK Spark Plug Co Ltd filed Critical NGK Spark Plug Co Ltd
Publication of CN110715751A publication Critical patent/CN110715751A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
    • G01K1/08—Protective devices, e.g. casings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/02—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/02—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow
    • G01K13/024—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow of moving gases
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G01K2007/163—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements provided with specially adapted connectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K2205/00—Application of thermometers in motors, e.g. of a vehicle
    • G01K2205/04—Application of thermometers in motors, e.g. of a vehicle for measuring exhaust gas temperature

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

The invention provides a temperature sensor which suppresses breakage of a temperature sensing element caused by thermal shock. A temperature sensor is provided with: a temperature sensing element including a temperature sensing portion and an element electrode line; and a sheath member which is disposed on the rear end side of the temperature sensing element and has a sheath tube and a sheath core wire electrically connected to the element electrode wire, wherein the temperature sensor further includes a conductive tube which extends in the axial direction, accommodates the element electrode wire on the front end side of the conductive tube, accommodates the sheath core wire on the rear end side of the conductive tube, and electrically connects the element electrode wire and the sheath core wire, the conductive tube has a tubular or a tubular part in cross section, the linear expansion coefficient of the conductive tube is larger than the linear expansion coefficient of the element electrode wire, the element electrode wire is fixed inside the conductive tube, and a gap in the axial direction is provided between the rear end of the temperature sensing portion and the front end of the conductive tube.

Description

Temperature sensor
Technical Field
The present invention relates to a temperature sensor including a temperature sensing element such as a thermistor element or a Pt resistor element.
Background
As a temperature sensor for detecting the temperature of exhaust gas or the like of an automobile or the like, a temperature sensor using a temperature change in the resistance of a temperature sensing element such as a thermistor or a Pt resistor is known.
As shown in fig. 6, such a temperature sensor is generally configured by electrically connecting a pair of element electrode wires 100A extending toward the rear end side of a temperature sensing element 100 (temperature sensing unit 100B) and a sheath core wire 200A of a sheath member 200, accommodating them in a metal tube 300, and then filling a gap in the metal tube 300 with a cement (segment) 400 such as alumina (see patent document 1).
Here, the length of the temperature sensor varies depending on the application, and it is difficult to prepare a temperature sensor in which the length of the element electrode wire 100A of the temperature sensing element 100 and the length of the sheath member 200 are changed one by one. Further, since the element electrode line 100A is usually made of a noble metal such as pt—rh line, the length of the element electrode line 100A increases according to the length of the temperature sensor, which leads to an increase in cost.
Therefore, in the temperature sensor described in patent document 1, the element electrode wire 100A and the sheath member 200 can be used in common even if the length of the temperature sensor is changed by connecting the element electrode wire 100A and the sheath core wire 200A with the tube 500 of conductive metal and changing the length of the tube 500.
Prior art literature
Patent literature
Patent document 1: japanese patent application laid-open No. 2017-15701 (FIG. 1, FIG. 2, paragraph 0027)
Disclosure of Invention
Problems to be solved by the invention
Here, the distal end of the tube 500 has an inner diameter slightly larger than the outer diameter of the element electrode wire 100A, and the rear end of the tube 500 has an inner diameter slightly larger than the outer diameter of the sheath core wire 200A. Further, the element electrode wire 100A and the sheath core wire 200A are electrically connected by accommodating the element electrode wire 100A and the sheath core wire 200A at both ends of the tube 500, respectively, and crimping or welding them to both ends of the tube 500.
When the element electrode wire 100A is inserted into the distal end of the tube 500, the distal end of the tube 500 is positioned in contact with the rear end of the temperature sensing unit 100B of the temperature sensing element 100.
However, the tube 500 uses a heat-resistant alloy that is cheaper than the element electrode wire 100A and has a higher thermal expansion coefficient. Therefore, as shown in fig. 7, at a high temperature, the tube 500 is extended from the element electrode wire 100A with the welded portion (fixed portion) W as a starting point, and the distal end 500s of the tube 500 presses the rear end side of the temperature sensing portion 100B. Then, the element electrode wire 100A is pulled toward the rear end side via the welded portion W by the reaction force of the pressing force, and there is a problem that the connection portion B between the element electrode wire 100A and the temperature sensing portion 100B breaks.
Accordingly, an object of the present invention is to provide a temperature sensor in which breakage of a temperature sensitive element due to thermal shock is suppressed.
Solution for solving the problem
In order to solve the above problems, the present invention provides a temperature sensor including: a temperature sensing element including a temperature sensing portion and an element electrode line extending from the temperature sensing portion to a rear end side; and a sheath member disposed on a rear end side of the temperature sensing element and having a sheath core wire electrically connected to the element electrode wire and a sheath outer tube having the sheath core wire in an insulating material, wherein the temperature sensor further includes a conductive tube extending in an axial direction, the conductive tube accommodating the element electrode wire on a front end side thereof and accommodating the sheath core wire on a rear end side thereof, the sheath member electrically connecting the element electrode wire and the sheath core wire, the conductive tube having a cross section in a shape of a cylinder or a part of a cylinder, a linear expansion coefficient of the conductive tube being larger than a linear expansion coefficient of the element electrode wire, the element electrode wire being fixed to an inner side of the conductive tube, and a gap D1 in the axial direction being provided between a rear end of the temperature sensing portion and a front end of the conductive tube.
The length of the temperature sensor varies depending on the application, and the preparation of the temperature sensor in which the length of the element electrode wire of the temperature sensing element, the length of the sheath member, and the lengthening of the expensive element electrode wire are each changed leads to an increase in cost.
Therefore, with this temperature sensor, a conductive tube having a linear expansion coefficient larger than that of the element electrode wire and inexpensive is used for electrical connection between the element electrode wire and the sheath core wire, and even if the length of the temperature sensor is changed, the common element electrode wire and sheath member can be used by changing the length of the conductive tube.
Further, by providing the gap D1, even when the conductive pipe is extended at a high temperature, the state in which the distal end of the conductive pipe is separated from the rear end of the temperature sensing portion can be maintained, and since the distal end of the conductive pipe does not press the temperature sensing portion, occurrence of the following situation can be suppressed: under the reaction force of the pressing force, the element electrode wire is pulled toward the rear end side, and the connection portion between the element electrode wire and the temperature sensing portion is broken. Thus, breakage of the temperature sensing element due to thermal shock can be suppressed.
In the temperature sensor according to the present invention, the relationship of D1 > (L1/10) may be satisfied with respect to a length L1 in the axial direction from the distal end of the conductive pipe to the distal end of the fixing portion between the conductive pipe and the element electrode wire.
The conductive tube is extended by an amount of substantially (L1/10) or less with respect to the length L1. Therefore, with this temperature sensor, since the relationship of D1 > (L1/10) is satisfied, the conductive pipe and the temperature sensing portion can be reliably separated even at high temperature.
In the temperature sensor according to the present invention, a radial gap D2 may be provided between the distal end of the conductive pipe and the element electrode wire.
In some cases, the temperature sensing unit vibrates in the radial direction along with the running of the vehicle, etc., and the element electrode wire also vibrates in the radial direction along with the running of the vehicle. At this time, if the element electrode wire is abutted against the edge portion of the distal end of the conductive pipe, the conductive pipe having rigidity as compared with the element electrode wire does not move, and therefore stress acts on the element electrode wire in the abutted portion, which may cause disconnection.
Therefore, by providing the gap D2, even if the temperature sensing unit vibrates in the radial direction, the element electrode wire is less likely to come into contact with the tip of the conductive pipe, and occurrence of the following conditions can be suppressed: stress acts on the element electrode lines to cause breakage.
In the temperature sensor according to the present invention, the conductive pipe may be gradually expanded from a distal end of a fixing portion with the element electrode wire toward a distal end of the conductive pipe.
With this temperature sensor, the gap D2 can be reliably set.
In the temperature sensor of the present invention, the relationship of D2 > l2×tan θ may be satisfied with respect to a length L2 in the axial direction from the tip of the conductive pipe to a point P at which the conductive pipe starts to separate from the outer surface of the element electrode wire, and an opening angle θ between the outer surface of the element electrode wire and the inner surface of the conductive pipe at the point P.
The maximum amplitude in the radial direction of the temperature sensing portion and the element electrode wire when the temperature sensing portion vibrates in the radial direction is a range from the portion of the element electrode wire that is no longer held by the conductive tube, that is, the portion P, to the inner surface of the conductive tube that is in contact with the vicinity of the portion P. That is, if the angle formed by the tangent to the inner surface of the conductive pipe at the point P and the outer surface of the element electrode line is set to the open angle θ, the maximum amplitude is 2θ.
Therefore, if the gap D2 is made larger than the radial distance (l2×tan θ) between the extension line obtained by extending the tangential line to the distal end of the conductive pipe and the outer surface of the element electrode wire, the element electrode wire is less likely to come into contact with the distal end of the conductive pipe when the temperature sensing portion vibrates in the radial direction.
In the temperature sensor according to the present invention, the temperature sensing element may have a plurality of the element electrode lines extending from the temperature sensing portion, the sheath core wire and the conductive tube may be provided in a plurality so as to correspond to each of the plurality of element electrode lines, and the gap D1 may be provided in all of the plurality of conductive tubes.
With this temperature sensor, since the gaps D1 are provided in all of the plurality of conductive pipes, breakage of the connection portions between all of the plurality of element electrode lines and the temperature sensing portion can be suppressed.
ADVANTAGEOUS EFFECTS OF INVENTION
The invention can obtain a temperature sensor which can inhibit the damage of a temperature sensing element caused by thermal shock.
Drawings
Fig. 1 is a cross-sectional structure view of a part of a temperature sensor according to an embodiment of the present invention taken along an axial direction.
Fig. 2 is a partial enlarged view of fig. 1.
Fig. 3 is a partial enlarged view of fig. 2.
Fig. 4 is a schematic view showing a state in which the portion of fig. 3 is subjected to a cold-hot cycle.
Fig. 5 is a schematic diagram showing a state in which the Pt resistor portion of fig. 3 is vibrated.
Fig. 6 is a partial enlarged view of a cross section of a conventional temperature sensor.
Fig. 7 is a schematic view showing a state in which the portion of fig. 6 is subjected to a cold-hot cycle.
Description of the reference numerals
1. A temperature sensor; 10. a temperature sensing element; 11. a temperature sensing unit; 11e, the rear end of the temperature sensing part; 12. an element electrode line; 20. a sheath member; 21. a sheath core wire; 22. a sheath tube; 80. a conductive tube; 80s, the front end of the conductive tube; o, axis; w1, a fixing portion (welded portion) of the element electrode wire; and P, a part of the conductive tube which starts to leave from the outer surface of the element electrode wire.
Detailed Description
Hereinafter, embodiments of the present invention will be described.
Fig. 1 shows a cross-sectional structure of a part of a temperature sensor 1 according to an embodiment of the present invention, which is cut along an axis O direction. The temperature sensor 1 of the embodiment is configured to house the sheath member 20 from the rear end side of the metal member 30.
The temperature sensor 1 is inserted through and attached to an opening (not shown) in a side wall of an exhaust pipe of an internal combustion engine, and detects the temperature of exhaust gas of an automobile. The temperature sensor 1 is also subjected to a heating-cooling cycle in the above temperature range, with a rapid change in the temperature of the exhaust gas from a low temperature region of about 0 ℃ to a high temperature region of about 1000 ℃.
The temperature sensor 1 includes: a Pt resistor element (temperature sensing element) 10; a sheath member 20 connected to the Pt resistor element 10; a tubular metal conductive pipe 80 to be described later; a bottomed cylindrical metal member 30 accommodating the Pt resistor element 10 and the sheath member 20; a mounting portion 50 fitted to the outer periphery of the metal member 30; a nut portion 60 fitted to the outer periphery of the mounting portion 50 with a gap; a tubular metal outer tube 70 attached to the rear end side of the attachment portion 50; and an auxiliary ring 26 made of heat-resistant rubber, which is attached to the rear end of the outer tube 70, and leads 24 are led out to the outside through the auxiliary ring 26.
In the temperature sensor 1 of the present invention, the metal member 30 extends in the axis O direction, the bottom side of the metal member 30 is referred to as "front end", and the open end side of the metal member 30 is referred to as "rear end".
The Pt resistor element (temperature sensing element) 10 has: a Pt resistor portion (temperature sensing portion) 11 for measuring temperature; and a pair of element electrode lines 12, the pair of element electrode lines 12 extending from one end (rear end side) of the Pt resistor portion 11.
The Pt resistor portion 11 is formed by sandwiching a film-like metal resistor with a ceramic layer, and is substantially plate-shaped as a whole, and the Pt resistor portion 11 is disposed in the metal member 30 so that the longitudinal direction thereof is parallel to the axis O direction of the temperature sensor 1 (metal member 30). The metal resistor is formed of a composition mainly composed of platinum (Pt) (50 mass% or more), and a pair of element electrode lines 12 are separately connected to the metal resistor. Further, since the resistance value of the metal resistor changes according to a temperature change, the change can be detected as a voltage change between the pair of element electrode lines 12. As the ceramic layer, a composition having an alumina purity of 99.9 mass% or more can be used. In addition to the resistor such as Pt, a thermistor may be used as the temperature sensing unit.
The sheath member 20 has a sheath core wire 21 connected to the pair of element electrode wires 12 of the Pt resistor element 10, and a metal sheath outer tube 22 accommodating the sheath core wire 21, and SiO is filled between the sheath core wire 21 and the inner surface of the sheath outer tube 22 2 An insulating material is formed.
In general, the element electrode wire 12 is an expensive pt—rh wire or the like, and therefore, is connected to an inexpensive sheath core wire 21 made of SUS or the like, thereby reducing the cost.
In the present embodiment, the metal member 30 is formed of SUS310S, the front end of the metal member 30 is closed and extends straight in parallel with the axis O direction, the metal member 30 further has a tapered portion 35 that expands in diameter toward the rear end side, and a portion of the metal member 30 on the rear end side of the tapered portion 35 extends straight.
The inner diameter of the portion of the metal member 30 on the tip side of the tapered portion 35 is smaller than the outer diameter of the sheath tube 22 of the sheath member 20 and larger than the maximum outer diameter of the Pt resistor portion 11. On the other hand, the inner diameter of the portion of the metal member 30 on the rear end side of the tapered portion 35 is larger than the outer diameter of the sheath tube 22 of the sheath member 20.
Thus, when the sheath member 20 and the Pt resistor element 10 are inserted from the rear end side of the metal member 30, the front end side of the sheath member 20 is abutted against the tapered portion 35 to position the insertion depth. In addition, the distal end side of the sheath member 20 closes the opening of the metal member 30, and at least the Pt resistor element 10 and the conductive tube 80, which is a connection portion between the element electrode wire 12 and the sheath core wire 21, are housed in the internal space of the metal member 30. In addition, cement 40 is filled in the internal space.
The mounting portion 50 is formed in a substantially cylindrical shape in which a center hole through which the metal member 30 passes is opened in the axis O direction, and a flange portion 51 having a large diameter, a cylindrical sheath portion 52 having a diameter smaller than that of the flange portion 51, a 1 st step portion 54 constituting a front end side of the sheath portion 52, and a 2 nd step portion 55 constituting a rear end side of the sheath portion 52 and having a diameter smaller than that of the 1 st step portion 54 are formed in this order from the front end side of the temperature sensor 1. The front end surface of the flange 51 has a tapered seat surface 53, and when a nut 60 to be described later is screwed to the exhaust pipe, the seat surface 53 is pressed against a corner (not shown) of the side wall of the exhaust pipe to seal the exhaust pipe.
The mounting portion 50 is pressed into the outer periphery of the rear end portion of the metal member 30, and the 2 nd step portion 55 and the metal member 30 are fixed by laser welding over the entire periphery.
The outer tube 70 is pressed into the outer periphery of the 1 st step 54, and both are fixed by full-periphery laser welding. The outer tube 70 accommodates and holds a connection portion between the lead wire 24 and the sheath core wire 21 led out from the sheath member 20.
The nut portion 60 has a center hole having a diameter slightly larger than the outer periphery of the outer tube 70 in the axis O direction, and the nut portion 60 has a screw portion 62 and a hexagonal nut portion 61 having a diameter larger than the screw portion 62 formed from the front end side. The nut portion 60 is fitted to the outer periphery of the mounting portion 50 (the outer tube 70) with a gap therebetween in a state where the front surface of the screw portion 62 is brought into contact with the rear surface of the flange portion 51 of the mounting portion 50, and is rotatable in the axis O direction.
The temperature sensor 1 is attached to the side wall of the exhaust pipe by screwing the screw portion 62 into a predetermined screw hole of the exhaust pipe.
Two sheath wires 21 are led out from the rear end of the sheath tube 22 of the sheath member 20, and the distal ends of the sheath wires 21 are connected to a crimp terminal 23, and the crimp terminal 23 is connected to a lead 24. Further, each sheath core 21 and the crimp terminal 23 are insulated by an insulating tube 25.
Each lead 24 is led out to the outside through a lead through hole of the auxiliary ring 26 fitted inside the rear end of the outer tube 70, and is connected to an external circuit through a connector not shown.
In addition, cement 40 of alumina or the like is filled in the gaps between the inner surface of the metal member 30 and the Pt resistor element 10 and between the inner surface of the metal member 30 and the sheath member 20, and the cement 40 holds the Pt resistor element 10 and the sheath member 20 to suppress vibration thereof. As the cement 40, a material having high heat resistance and high insulation property can be used.
Next, a structure including a conductive tube 80 as a characteristic part of the present invention will be described with reference to fig. 2 to 5. Fig. 2 is a partially enlarged view of fig. 1, fig. 3 is a partially enlarged view of fig. 2, fig. 4 is a schematic view showing a state in which the portion of fig. 3 is subjected to a cold-hot cycle, and fig. 5 is a schematic view showing a state in which the Pt resistor portion 11 of fig. 3 is vibrated.
As described above, it is difficult to prepare temperature sensors in which the lengths of the element electrode wires 12 of the temperature sensing element 10 and the lengths of the sheath members 20 are changed, respectively, in accordance with the lengths of the temperature sensors 1. In addition, since the element electrode line 12 is expensive, lengthening the element electrode line 12 causes an increase in cost.
Therefore, the element electrode wire 12 and the sheath core wire 21 are electrically connected via the conductive tube 80 using the conductive tube 80 which is cheaper than the element electrode wire 12 (for example, a heat-resistant alloy such as Inconel (registered trademark)) and has a larger linear expansion coefficient than that of the element electrode wire 12. Thus, even if the length of the temperature sensor 1 is changed, the common element electrode wire 12 and the sheath member 20 can be used by changing the length of the conductive pipe 80.
As shown in fig. 2, in the present example, since the diameter of the sheath core wire 21 is larger than the diameter of the element electrode wire 12, the conductive pipe 80 extends straight from the front end side 80f in parallel with the axis O direction, and has a tapered portion 81 that expands in diameter toward the rear end side, and a portion of the conductive pipe 80 on the rear end side of the tapered portion 81 extends straight to the rear end side 80e.
The element electrode wire 12 is electrically connected to the sheath core wire 21 by accommodating the front end side of the sheath core wire 21 in the rear end side 80e of the conductive tube 80, accommodating the rear end side of the element electrode wire 12 in the front end side 80f, and welding the insertion portions by resistance welding or the like from the outside of the tapered portion 81. At this time, the element electrode wire 12 and the sheath core wire 21 are fixed to the inside of the conductive tube 80 at the welded portions W1 and W2, respectively.
As shown in fig. 3, in the present embodiment, a gap D1 in the axis O direction is provided between the rear end 11e of the Pt resistor portion 11 and the front end 80s of the conductive pipe 80.
In the present embodiment, the distal end 80s of the conductive tube 80 is expanded in diameter, and a gap D2 is provided between the distal end 80s of the conductive tube 80 and the element electrode line 12 in the radial direction (the direction perpendicular to the axis O direction).
In the present embodiment, the conductive pipe 80 gradually spreads in a horn shape from the tip of the welded portion W1, which is a fixing portion with the element electrode wire 12, toward the tip of the conductive pipe 80.
In the present embodiment, the relationship D2 > L2×tan θ is satisfied with respect to the length L2 in the axis O direction from the tip 80s of the conductive pipe 80 to the point P where the conductive pipe 80 starts to separate from the outer surface of the element electrode wire 12 and the opening angle θ between the outer surface of the element electrode wire 12 and the inner surface of the conductive pipe 80 at the point P.
The reason for limiting D1 and D2 will be described with reference to fig. 4 and 5.
First, as shown in fig. 4, since the linear expansion coefficient of the conductive pipe 80 is higher than that of the element electrode line 12, the conductive pipe 80 is extended from the welded portion (fixed portion) W1 to the element electrode line 12 at a high temperature as shown in fig. 4. Therefore, by providing the gap D1, even if the conductive pipe 80 is elongated at a high temperature, the state in which the front end 80s of the conductive pipe 80 is separated from the rear end 11e of the Pt resistor portion 11 can be maintained.
Thus, the front end 80s of the conductive tube 80 does not press the rear end 11e of the Pt resistor part 11, and therefore occurrence of the following situation can be suppressed: the element electrode wire 12 is pulled toward the rear end side via the welding portion W by the reaction force of the pressing force, and the connection portion B between the element electrode wire 12 and the Pt resistor portion 11 is broken.
Thus, breakage of the Pt resistor element 10 caused by thermal shock can be suppressed.
Further, the gap D1 is required to be provided at normal temperature.
The conductive tube 80 extends by an amount of substantially (L1/10) or less with respect to the length L1 in the axial line O direction from the distal end 80s of the conductive tube 80 to the distal end of the fixed portion (welded portion W1). Therefore, if the relationship of D1 > (L1/10) is satisfied, the conductive pipe 80 and the Pt resistor portion 11 can be reliably separated even at high temperature.
As shown in fig. 5, as D2, the Pt resistor portion 11 vibrates in the radial direction along with the running of the vehicle or the like, and the element electrode wire 12 also vibrates in the radial direction. At this time, if the element electrode wire 12 is abutted against the edge portion of the distal end 80s of the conductive pipe 80, the conductive pipe 80 having rigidity compared with the element electrode wire 12 does not move, and therefore stress acts on the element electrode wire 12 at the abutted portion, which may cause disconnection.
Therefore, by providing the gap D2, when the Pt resistor portion 11 vibrates in the radial direction, the element electrode wire 12 is less likely to come into contact with the tip end 80s of the conductive pipe 80, and occurrence of the following situation can be suppressed: stress acts on the element electrode line 12 to cause disconnection.
Here, the maximum amplitude in the radial direction of the Pt resistor portion 11 and the element electrode wire 12 is a range from the portion of the element electrode wire 12 that is no longer held by the conductive tube 80, that is, the portion P, to the inner surface of the conductive tube 80 that is in contact with the vicinity of the portion P. That is, if the angle formed by the tangent to the inner surface of the conductive pipe 80 at the point P and the outer surface of the element electrode line 12 is set to the open angle θ, the maximum amplitude is 2θ.
Therefore, if the gap D2 is made larger than the distance Dx in the radial direction between the extension line EL obtained by extending the tangent to the distal end 80s of the conductive pipe 80 and the outer surface of the element electrode wire 12, the element electrode wire 12 is less likely to come into contact with the distal end 80s of the conductive pipe 80 when the Pt resistor portion 11 vibrates in the radial direction.
Further, since the distance dx=l2×tan θ and D2 > Dx, the relationship of D2 > l2×tan θ is satisfied, that is, the distal end 80s side of the conductive pipe 80 preferably expands radially outward than the extension line EL at the portion P.
The portion P can be obtained from a cross-sectional image of the element electrode line 12 and the conductive pipe 80, and specifically, in the cross-sectional image, a straight line connecting the portion P and a midpoint position Q (see fig. 5) of the length L1 is regarded as a tangent line (and an extension line EL) at the portion P that is tangent to the inner surface of the conductive pipe 80.
The present invention is not limited to the above-described embodiments, but, of course, relates to various modifications and equivalents included in the spirit and scope of the present invention. For example, a thermistor sintered body may be used as the temperature sensing unit instead of the Pt resistor unit 11. As the thermistor sintered body, (Sr, Y) (Al, mn, fe) O can be used 3 The perovskite type oxide of the basic composition is not limited thereto.
In addition, when using a thermistor sintered body or the like, there is a case where the outside of the temperature sensing portion is covered with a sealing material such as glass in order to prevent degradation of the temperature sensing portion due to reduction. In this case, a portion including the coating material (glass) and integrated with the temperature sensing portion is also regarded as the temperature sensing portion. That is, the "rear end of the temperature sensing portion" refers to the rear end of the coating material (glass) of the outermost surface of the temperature sensing portion.
In the above embodiment, the diameter of the portion of the conductive tube on the tip side of the tapered portion is smaller than the diameter of the portion of the conductive tube on the rear end side of the tapered portion, but the shape of the conductive tube may be variously changed depending on the outer diameters of the element electrode wire and the sheath core wire connected to the conductive tube. The cross section of the conductive pipe is not limited to a cylindrical shape, and may be a part of a cylindrical shape, for example, a C-letter shape.
The method of fixing the element electrode wire to the inside of the conductive tube may be a method other than welding, such as crimping, or the like.
In the above embodiment, the space between the inner surfaces of the sheath core wire 21 and the sheath tube 22 is filled with SiO 2 The insulating material formed is not limited thereto, and may be filled with MgO or Al 2 O 3 An insulating material is formed.

Claims (7)

1. A temperature sensor is provided with:
a temperature sensing element including a temperature sensing portion and an element electrode line extending from the temperature sensing portion to a rear end side; and
a sheath member disposed at a rear end side of the temperature sensing element and having a sheath core wire electrically connected to the element electrode wire and a sheath outer tube having the sheath core wire in an insulating material,
the temperature sensor is characterized in that,
the temperature sensor further comprises a conductive tube extending in the axial direction, the conductive tube accommodating the element electrode wire at the front end side of the conductive tube and the sheath core wire at the rear end side of the conductive tube, and electrically connecting the element electrode wire and the sheath core wire, the conductive tube having a tubular or a part of a tubular shape in cross section,
the coefficient of linear expansion of the conductive tube is greater than the coefficient of linear expansion of the element electrode wire,
the element electrode wire is fixed to the inner side of the conductive tube,
a gap D1 in the axial direction is provided between the rear end of the temperature sensing unit and the front end of the conductive pipe.
2. A temperature sensor according to claim 1, wherein,
the relation D1 > (L1/10) is satisfied with respect to a length L1 in the axial direction from the tip of the conductive tube to the tip of the fixing portion between the conductive tube and the element electrode wire.
3. A temperature sensor according to claim 1 or 2, characterized in that,
a radial gap D2 is provided between the leading end of the conductive pipe and the element electrode wire.
4. A temperature sensor according to claim 3, wherein,
the conductive tube gradually expands from a front end of a fixing portion with the element electrode wire toward a front end of the conductive tube.
5. A temperature sensor according to claim 3, wherein,
with respect to a length L2 in the axial direction from a front end of the conductive pipe to a position (P) where the conductive pipe starts to separate from an outer surface of the element electrode wire, an opening angle θ between the outer surface of the element electrode wire at the position (P) and an inner surface of the conductive pipe,
satisfies the relationship of D2 > L2 xtan theta.
6. A temperature sensor according to claim 4, wherein,
with respect to a length L2 in the axial direction from a front end of the conductive pipe to a position (P) where the conductive pipe starts to separate from an outer surface of the element electrode wire, an opening angle θ between the outer surface of the element electrode wire at the position (P) and an inner surface of the conductive pipe,
satisfies the relationship of D2 > L2 xtan theta.
7. A temperature sensor according to claim 1 or 2, characterized in that,
the temperature sensing element has a plurality of element electrode wires extending from the temperature sensing portion,
the sheath core wire and the conductive tube are provided in plural in a manner corresponding to each of the plural element electrode wires,
the gaps D1 are provided at all of the plurality of conductive pipes.
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