CN110715751A - Temperature sensor - Google Patents

Temperature sensor Download PDF

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Publication number
CN110715751A
CN110715751A CN201910630720.9A CN201910630720A CN110715751A CN 110715751 A CN110715751 A CN 110715751A CN 201910630720 A CN201910630720 A CN 201910630720A CN 110715751 A CN110715751 A CN 110715751A
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CN
China
Prior art keywords
element electrode
electrode wire
conductive tube
sheath
tube
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Granted
Application number
CN201910630720.9A
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Chinese (zh)
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CN110715751B (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
Application granted granted Critical
Publication of CN110715751B publication Critical patent/CN110715751B/en
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    • 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
    • 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
    • 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 damage of a temperature sensing element caused by thermal shock. A temperature sensor is provided with: a temperature sensing element including a temperature sensing part and an element electrode line; and a sheath member disposed on a rear end side of the temperature sensing element, the sheath member having a sheath outer tube and a sheath core wire electrically connected to the element electrode wire, wherein the temperature sensor further includes a conductive tube extending in the 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 and electrically connecting the element electrode wire and the sheath core wire, the conductive tube having a cross section in a shape of a cylindrical or a part of a cylindrical shape, a coefficient of linear expansion of the conductive tube being larger than a coefficient of linear expansion of the element electrode wire, the element electrode wire being fixed to an inner side of the conductive tube, and a gap in the axial direction is provided between a rear end of the temperature sensing portion and a 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, there is known a temperature sensor using a change in the temperature of the resistance of a temperature sensing element such as a thermistor or a Pt resistor.
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 part 100B) and a sheath wire 200A of a sheath member 200, housing them inside a metal tube 300, and then filling a gap inside the metal tube 300 with a cement (center) 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. In addition, since the element electrode line 100A generally uses a noble metal such as Pt — Rh wire, the cost increases due to the increase in length of the element electrode line 100A corresponding to the increase in length of the temperature sensor.
Therefore, in the temperature sensor described in patent document 1, the element electrode wire 100A and the sheath wire 200A are connected by the conductive metal tube 500, and the length of the tube 500 is changed, whereby the common element electrode wire 100A and the common sheath member 200 can be used even if the length of the temperature sensor changes.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2017-15701 (FIG. 1, FIG. 2, paragraph 0027)
Disclosure of Invention
Problems to be solved by the invention
Here, the front 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. Also, the element electrode wire 100A and the sheath core wire 200A are electrically connected by accommodating them in both ends of the tube 500 and crimping or welding them to both ends of the tube 500, respectively.
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 by abutting the rear end of the temperature sensing part 100B of the temperature sensing element 100.
However, the tube 500 uses a heat-resistant alloy that is less expensive and has a higher thermal expansion rate than the element electrode wire 100A. Therefore, as shown in fig. 7, at high temperature, the tube 500 is extended from the element electrode wire 100A starting from the welded portion (fixed portion) W, and the tip 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 is broken.
Accordingly, an object of the present invention is to provide a temperature sensor in which breakage of a temperature sensing element due to thermal shock is suppressed.
Means for solving the problems
In order to solve the above problem, 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 and electrically connecting the element electrode wire and the sheath core wire, the conductive tube having a cross section in a shape of a cylindrical or a part of a cylindrical shape, a coefficient of linear expansion of the conductive tube being larger than a coefficient of linear expansion 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 provision of a temperature sensor in which the length of the element electrode wire of the temperature sensing element and the length of the sheath member are changed and the lengthening of the expensive element electrode wire lead to an increase in cost.
Therefore, according to this temperature sensor, the inexpensive conductive tube having a coefficient of linear expansion larger than that of the element electrode wire is used for the electrical connection between the element electrode wire and the sheath wire, and even if the length of the temperature sensor changes, the common element electrode wire and the sheath member can be used by changing the length of the conductive tube.
Further, by providing the gap D1, even if the contact tube is extended at a high temperature, the state in which the distal end of the contact tube is separated from the rear end of the temperature sensing unit can be maintained, and the distal end of the contact tube does not press the temperature sensing unit, so that occurrence of the following can be suppressed: the element electrode wire is pulled toward the rear end side by a reaction force of the pressing force, and the connection portion between the element electrode wire and the temperature sensing portion is broken. Therefore, breakage of the temperature sensing element due to thermal shock can be suppressed.
In the temperature sensor according to the present invention, a relationship of D1 > (L1/10) may be satisfied with respect to a length L1 in the axial direction from a distal end of the conductive tube to a distal end of a fixing portion between the conductive tube and the element electrode wire.
The amount of extension of the conductive tube with respect to the length L1 is substantially (L1/10) or less. Therefore, with this temperature sensor, the relationship of D1 > (L1/10) is satisfied, and therefore, the conductive tube and the temperature sensing part can be reliably separated even at high temperatures.
In the temperature sensor of the present invention, a radial gap D2 may be provided between the tip end of the conductive tube and the element electrode wire.
As the vehicle travels, the temperature sensing unit may vibrate in the radial direction, and the element electrode wire may vibrate in the radial direction. In this case, if the element electrode wire abuts on the edge portion of the distal end of the conductive tube, the conductive tube having rigidity as compared with the element electrode wire does not move, and therefore stress may act on the element electrode wire at the abutting 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 distal end of the conductive tube, and the occurrence of: stress acts on the element electrode line to cause disconnection.
In the temperature sensor according to the present invention, the conductive tube may be gradually expanded from a distal end of the fixing portion with respect to the element electrode wire toward a distal end of the conductive tube.
With this temperature sensor, the gap D2 can be reliably provided.
In the temperature sensor according to the present invention, a relationship of D2 > L2 × tan θ may be satisfied with respect to a length L2 in the axial direction from a tip of the contact tube to a point P where the contact tube starts to separate from an outer surface of the element electrode wire, and an open angle θ between the outer surface of the element electrode wire and an inner surface of the contact tube at the point P.
The maximum amplitude in the radial direction of the temperature sensing unit and the element electrode wire when the temperature sensing unit vibrates in the radial direction is a range from the portion of the element electrode wire that is not held by the contact tube to the inner surface of the contact tube in the vicinity of the portion P. That is, when an angle formed by a tangent line to the inner surface of the conductive tube at the position P and the outer surface of the element electrode wire is defined as an open angle θ, the maximum amplitude is 2 θ.
Therefore, if the gap D2 is made larger than the distance (L2 × tan θ) in the radial direction between the outer surface of the element electrode wire and the extension line obtained by extending the tangent line to the tip of the conductive tube, the element electrode wire is less likely to come into contact with the tip of the conductive tube when the temperature sensing section vibrates in the radial direction.
In the temperature sensor according to the present invention, the temperature sensing element may include a plurality of element electrode wires extending from the temperature sensing unit, the sheath wire and the conductive tube may be provided in a plurality corresponding to the respective element electrode wires of the plurality of element electrode wires, and the gap D1 may be provided in all of the plurality of conductive tubes.
In this temperature sensor, since the gaps D1 are provided in all of the plurality of conductive tubes, the connection portions between all of the plurality of element electrode wires and the temperature sensing unit can be prevented from being broken.
ADVANTAGEOUS EFFECTS OF INVENTION
The present invention can provide a temperature sensor in which damage to a temperature sensing element due to thermal shock is suppressed.
Drawings
Fig. 1 is a cross-sectional structural view of a temperature sensor according to an embodiment of the present invention, partially cut along an axial direction.
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 cooling-heating cycle.
Fig. 5 is a schematic diagram showing a state in which vibration is generated in the Pt resistor section of fig. 3.
Fig. 6 is a partially enlarged cross-sectional view 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 cooling-heating 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. an outer sheath tube; 80. a conductive tube; 80s, the front end of the conductive tube; o, an axis; w1, a fixed portion (welded portion) of the element electrode wire; p, the position where the conductive tube 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 obtained by cutting a part of a temperature sensor 1 according to an embodiment of the present invention along an axis O direction. The temperature sensor 1 according to 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 into 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. Further, the temperature sensor 1 is subjected to a cooling-heating cycle of temperature rise-cooling in the above temperature range, as the temperature of the exhaust gas rapidly changes from a low temperature range of about 0 ℃ to a high temperature range 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 cylindrical metal conductive tube 80 described later; a bottomed cylindrical metal member 30 that houses 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 with a gap on the outer periphery of the mounting portion 50; a cylindrical metal outer cylinder 70 attached to the rear end side of the attachment portion 50; and an auxiliary ring 26 made of heat-resistant rubber attached to the rear end of the outer cylinder 70, and through which the lead 24 is 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, and the bottom side of the metal member 30 is referred to as the "front end" and the open end side of the metal member 30 is referred to as the "rear end".
The Pt resistor element (temperature sensing element) 10 has: a Pt resistor section (temperature sensing section) 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 section 11.
The Pt resistor portion 11 is configured by sandwiching a film-shaped metal resistor by ceramic layers, and is substantially plate-shaped as a whole, and the Pt resistor portion 11 is disposed in the metal member 30 such that the longitudinal direction thereof is parallel to the axis O direction of the temperature sensor 1 (metal member 30). The metal resistor is mainly composed of platinum (Pt) (50 mass% or more), and the pair of element electrode lines 12 are separately connected to the metal resistor. Further, since the resistance value of the metal resistor changes in accordance with a change in temperature, the change can be detected as a change in voltage between the pair of element electrode lines 12. The ceramic layer may have a composition with an alumina purity of 99.9 mass% or more. Further, as the temperature sensing unit, a thermistor can be used in addition to the resistor of Pt or the like.
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, respectively, and a metal sheath tube 22 accommodating the sheath core wire 21, and a gap between the sheath core wire 21 and the inner surface of the sheath tube 22 is filled with SiO2The insulating material is formed.
Since the element electrode wire 12 is usually an expensive Pt — Rh wire or the like, it is connected to an inexpensive sheath-core wire 21 made of SUS or the like, thereby achieving cost reduction.
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 to the axis O direction, the metal member 30 further has a tapered portion 35 whose diameter is increased 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 metal member 30 on the tip side of the tapered portion 35 is smaller than the outer diameter of the sheath outer 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 outer 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 distal end side of the sheath member 20 abuts on the tapered portion 35 to position the insertion depth. Further, 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 site between the element electrode wire 12 and the sheath wire 21, are housed in the internal space of the metal member 30. In addition, the 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 is inserted is open 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 forming a front end side of the sheath portion 52, and a 2 nd step portion 55 forming 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 a front end side of the temperature sensor 1. The flange portion 51 has a tapered seat surface 53 at its distal end surface, and when a nut portion 60 described later is screwed into the exhaust pipe, the seat surface 53 is pressed against and sealed against a corner portion (not shown) of the side wall of the exhaust pipe.
The mounting portion 50 is press-fitted 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 thereof.
The outer cylinder 70 is press-fitted into the outer periphery of the 1 st stepped portion 54, and the both are fixed by full-periphery laser welding. The outer cylinder 70 accommodates and holds a connection portion between the lead wire 24 and the sheath wire 21 led out from the sheath member 20.
The nut portion 60 has a center hole slightly larger in diameter than the outer periphery of the outer cylinder 70 in the axis O direction, and the nut portion 60 is formed with a threaded portion 62 and a hexagonal nut portion 61 larger in diameter than the threaded portion 62 from the tip end side. The nut portion 60 is fitted with a gap on the outer periphery of the mounting portion 50 (outer cylinder 70) and is rotatable in the axis O direction in a state where the front surface of the screw portion 62 is in contact with the rear surface of the flange portion 51 of the mounting portion 50.
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 drawn out from the rear end of the sheath outer tube 22 of the sheath member 20, the terminal end of each sheath wire 21 is connected to a crimp terminal 23, and the crimp terminal 23 is connected to a lead 24. The sheath wires 21 and the crimp terminals 23 are insulated by insulating tubes 25.
Each lead wire 24 is led out to the outside through a lead wire through hole of the auxiliary ring 26 fitted inside the rear end of the outer tube 70, and is connected to an external circuit via a connector not shown.
Further, a cement 40 such as alumina is filled in a gap between the inner surface of the metal member 30 and the Pt resistor element 10 and a gap 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 and suppresses vibration thereof. As the cement 40, a material having high thermal conductivity, high heat resistance, and high insulation may be used.
Next, a structure including the conductive tube 80 as a characteristic portion 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 a portion of fig. 3 is subjected to a cooling-heating cycle, and fig. 5 is a schematic view showing a state in which vibration is generated in the Pt resistor portion 11 of fig. 3.
As described above, it is difficult to prepare a temperature sensor in which the length of the element electrode wire 12 of the temperature sensing element 10 and the length of the sheath member 20 are changed one by one according to the length of the temperature sensor 1. In addition, since the element electrode line 12 is expensive, lengthening the element electrode line 12 leads to an increase in cost.
Therefore, the element electrode wire 12 and the sheath wire 21 are electrically connected to each other through the conductive tube 80, using the conductive tube 80 which is less expensive than the element electrode wire 12 (for example, a heat-resistant alloy such as Inconel (registered trademark)) and has a coefficient of linear expansion larger than that of the element electrode wire 12. Thus, even if the length of the temperature sensor 1 changes, the common element electrode wire 12 and the sheath member 20 can be used by changing the length of the conductive tube 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 conductor tube 80 extends straight from the distal end side 80f in parallel with the axis O direction and has a tapered portion 81 whose diameter is increased toward the rear end side, and a portion of the conductor tube 80 on the rear end side of the tapered portion 81 extends straight to the rear end side 80 e.
The element electrode wire 12 and the sheath wire 21 are electrically connected by accommodating the distal end side of the sheath wire 21 in the interior of the rear end side 80e of the conductive tube 80, accommodating the rear end side of the element electrode wire 12 in the interior of the distal 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 wire 21 are fixed to the inside of the conductive tube 80 at the welding 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 tube 80.
In the present embodiment, the tip 80s of the contact tube 80 is expanded in diameter, and a gap D2 in the radial direction (direction perpendicular to the axis O direction) is provided between the tip 80s of the contact tube 80 and the element electrode wire 12.
In the present embodiment, the lead tube 80 gradually flares from the tip of the welded portion W1, which is the fixed portion with the element electrode wire 12, toward the tip of the lead tube 80.
In the present embodiment, the relationship D2 > L2 × tan θ is satisfied with respect to the length L2 in the axial line O direction from the tip 80s of the contact tube 80 to the point P where the contact tube 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 contact tube 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, in D1, since the linear expansion coefficient of the conductive tube 80 is higher than that of the element electrode wire 12, the conductive tube 80 extends from the welded portion (fixed portion) W1 to the element electrode wire 12 at high temperature. Therefore, by providing the gap D1, even if the contact tube 80 is extended at a high temperature, the state in which the front end 80s of the contact tube 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 portion 11, and therefore, occurrence of: the element electrode line 12 is pulled toward the rear end side via the welded portion W by the reaction force of the pressing force, and the connection portion B between the element electrode line 12 and the Pt resistor portion 11 is broken.
Thus, breakage of the Pt resistor element 10 due to thermal shock can be suppressed.
Further, the gap D1 needs to be provided at normal temperature.
Further, the length L1 in the axial line O direction from the tip 80s of the contact tube 80 to the tip of the fixed portion (welded portion W1) is substantially equal to or less than (L1/10). Therefore, if the relationship of D1 > (L1/10) is satisfied, the conductive tube 80 and the Pt resistor portion 11 can be reliably separated even at high temperatures.
As shown in fig. 5, in D2, the Pt resistor portion 11 may vibrate in the radial direction as the vehicle travels, and the element electrode line 12 may vibrate in the radial direction. At this time, if the element electrode wire 12 abuts on the edge portion of the tip 80s of the conductive tube 80, the conductive tube 80 having rigidity compared to the element electrode wire 12 does not move, and therefore stress acts on the element electrode wire 12 at the abutting portion, possibly causing 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 80s of the conductive tube 80, and the occurrence of: 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 line 12 is a range from the portion of the element electrode line 12 that is not held by the contact tube 80, that is, the portion P, to the inner surface of the contact tube 80 in the vicinity of the portion P. That is, when an angle formed by a tangent line to the inner surface of the conductive tube 80 at the position P and the outer surface of the element electrode wire 12 is defined as the open angle θ, the maximum amplitude is 2 θ.
Therefore, if the gap D2 is made larger than the distance Dx in the radial direction between the outer surface of the element electrode wire 12 and the extension line EL obtained by extending the tangent line to the tip 80s of the conductive tube 80, the element electrode wire 12 is less likely to come into contact with the tip 80s of the conductive tube 80 when the Pt resistor portion 11 vibrates in the radial direction.
Further, since the distance Dx is L2 × tan θ and D2 > Dx, the relationship of D2 > L2 × tan θ is satisfied, that is, the tip 80s side of the conductive tube 80 preferably extends radially outward from the extension EL at the point P.
The portion P can be determined from a cross-sectional image of the element electrode wire 12 and the conductive tube 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 (and an extension line EL) to the inner surface of the conductive tube 80 at the portion P.
The present invention is not limited to the above-described embodiments, and naturally, it relates to various modifications and the like included in the spirit and scope of the present inventionThe same thing. For example, a thermistor sintered body may be used as the temperature sensing section instead of the Pt resistor section 11. As the thermistor sintered body, (Sr, Y) (Al, Mn, Fe) O can be used3A perovskite oxide having a basic composition, but is not limited thereto.
In addition, when a thermistor sintered body is used, for example, in order to prevent the temperature sensing part from being degraded by reduction, there is a mode in which the outside of the temperature sensing part is covered with a sealing material such as glass. In this case, a portion including the covering material (glass) integrated with the temperature sensing unit is also regarded as the temperature sensing unit. That is, the "rear end of the temperature sensing part" refers to the rear end of the covering (glass) on the outermost surface of the temperature sensing part.
In the above embodiment, the diameter of the portion of the contact tube on the front end side of the tapered portion is smaller than the diameter of the portion of the contact tube on the rear end side of the tapered portion, but the shape of the contact tube may be variously changed depending on the outer diameters of the element wire and the sheath wire connected to the contact 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, SiO is filled between the sheath core wire 21 and the inner surface of the sheath outer tube 222The insulating material formed is not limited thereto, but may be filled with MgO or Al2O3The insulating material is formed.

Claims (6)

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 on a rear end side of the temperature sensing element and having a sheath wire electrically connected to the element electrode wire and a sheath outer tube having the sheath wire in an insulating material,
the temperature sensor is characterized in that it is,
the temperature sensor further includes a conductive tube extending in the axial direction, the conductive tube accommodating the element electrode wire at a front end side thereof and accommodating the sheath wire at a rear end side thereof and electrically connecting the element electrode wire and the sheath wire, the conductive tube having a cross section in a shape of a cylinder or a part of a cylinder,
the conductive tube has a linear expansion coefficient greater than that of the element electrode wire,
the element electrode wire is fixed on 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 tube.
2. The temperature sensor according to claim 1,
a relationship of D1 > (L1/10) is satisfied with respect to a length L1 in the axial direction from a distal end of the conductive tube to a distal end of a fixing portion between the conductive tube and the element electrode wire.
3. The temperature sensor according to claim 1 or 2,
there is a radial gap D2 between the front end of the conductive tube and the element electrode wire.
4. The temperature sensor of claim 3,
the conductive tube gradually expands from the front end of the fixing portion with the element electrode wire toward the front end of the conductive tube.
5. The temperature sensor according to claim 3 or 4,
an open angle theta between the outer surface of the element electrode wire and the inner surface of the contact tube at a position (P) with respect to a length L2 in the axial direction from the tip of the contact tube to the position (P) where the contact tube starts to separate from the outer surface of the element electrode wire,
satisfies the relationship of D2 > L2 Xtan theta.
6. The temperature sensor according to any one of claims 1 to 5,
the temperature sensing element has a plurality of element electrode lines extending from the temperature sensing part,
a plurality of sheath-core wires and a plurality of conductive tubes are provided so as to correspond to the respective element electrode wires of the plurality of element electrode wires,
the gaps D1 are provided all at the plurality of conductive tubes.
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