JP4829007B2 - Temperature sensor - Google Patents

Description

  The present invention relates to a temperature sensor that includes a thermistor made of a metal oxide semiconductor, a metal resistor, or the like as a temperature sensing element, and the temperature sensing element is housed in a metal tube.

  Conventionally, a temperature sensing element, a sheath member in which a metal core wire having a temperature sensing element connected to the tip end and a lead wire for external circuit connection connected to the rear end is insulated and held inside the cylindrical member, and the tip A cylindrical metal tube that extends in the axial direction with the side closed and houses the temperature sensing element and the distal end side of the sheath member, and an attachment that supports the metal tube with the front end and rear end of the metal tube protruding. A temperature sensor including a member is known.

  In the above temperature sensor, the rear end side of the sheath member is surrounded by a metal storage member joined to the attachment member, and the metal storage member is in a state where the internal space communicates with the metal tube. It has become.

  And in the inside of the metal storage member, a polymer member such as rubber is stored for the purpose of preventing water or the like from entering the metal storage member, or the metal core wires on the side connected to the lead wire are in contact with each other. A polymer member such as a resin is accommodated for the purpose of prevention (Patent Document 1 (FIGS. 1 and 2)).

Such a temperature sensor is used for detecting the temperature of an object to be measured (exhaust gas or the like) in an environment where the vibration is intense, such as the inside of a catalytic converter and an exhaust pipe of an automobile.
JP 2004-157052 A

  By the way, in the above temperature sensor, it is common to fill the inside of the element housing member with a filler such as cement in order to protect the temperature sensitive element housed in the element housing member such as a metal tube from vibration. is there. In such a temperature sensor, a part of the filler may be pulverized due to vibration applied to the temperature sensor when used for a long time, and the fine particles of the filler may increase through the inside of the metal housing member. When moving to the molecular member, the fine particles scrape the polymer member, and fine particles of the polymer member may be generated. When the fine particles of the polymer member move to the tip side (temperature sensing element side) inside the metal storage member, for example, when the object whose temperature is detected is exhaust gas, the tip side of the metal storage member Is exposed to a relatively high temperature environment, the fine particles of the polymer member are burned, and there is a risk that the inside of the metal housing member and thus the inside of the metal tube will be in a low oxygen atmosphere.

  Here, when the temperature sensor is used beyond the endurance limit time of the temperature sensor in an environment where intense vibration is continuously applied, many polymer members are scraped by the filler. Therefore, many polymer members are burned. When many polymer members burn as described above, the inside of the metal tube and the metal housing member becomes an excessively low oxygen atmosphere, causing combustion accompanied by oxygen atoms constituting the temperature sensing element, and the temperature sensing element. There is a risk of causing characteristic changes.

  Therefore, the present invention has been made in view of such problems, and intense vibration is continuously applied to a temperature sensor that detects the temperature of an object to be measured in an environment where vibration is intense such as an exhaust pipe of an internal combustion engine. It is an object of the present invention to prevent a change in the characteristics of a temperature sensitive element even when the temperature sensor is used in an environment exceeding the endurance limit time of the temperature sensor.

The temperature sensor according to claim 1, which is configured to achieve the object, includes a temperature-sensitive element whose electrical characteristics change depending on temperature, the temperature-sensitive element connected to a front end portion, and an external circuit at a rear end portion. A sheath member having a pair of metal core wires to which connecting lead wires are connected, and a cylindrical member that insulates and holds the metal core wires in a state where the front end portion and the rear end portion of the metal core wires are projected; In a form that extends in the axial direction and has a cylindrical shape with the distal end closed, a metal tube that houses the distal end side of the tubular member of the temperature sensing element and the sheath member, and a rear end side of the sheath member that protrudes An attachment member that surrounds the outer side in the radial direction of the metal tube, a cylindrical metal storage member that is joined to the outer side in the radial direction of the attachment member and that stores the rear end side of the sheath member, and a polymer material The Lee A polymer member housed in the metal housing member so as to cover the periphery of the rear end portion of the wire or the metal core wire, and a filler filled in the metal tube so as to cover at least the temperature sensitive element, A temperature sensor comprising: an inner diameter of the metal housing member and an outer diameter of the tubular member of the sheath member on a tip side of the inside of the metal housing member where the polymer member is disposed. Is a member for blocking the passage of fine particles generated by crushing the filler by sealing a part of the space formed by the difference in diameter of the metal, and is formed in a cylindrical shape, and the outer diameter portion is the metal storage The large-diameter portion that contacts the member and the small-diameter portion that has an outer diameter portion smaller than the large-diameter portion and whose inner-diameter portion contacts the tubular member of the sheath member are made of a metal inorganic substance integrally formed. A stopper member, the stopper The tubular member of the small-diameter portion and the sheath member of the timber, characterized in that is fixed by caulking or welding, and the large diameter portion of the stopper member and said metal housing member is fixed by caulking or welding It is said.

  That is, when the temperature sensor of the present invention is used in an environment where vibration is applied, even if the filler is pulverized by vibration, a stopper member is provided. It can be prevented from moving.

  Therefore, according to such a temperature sensor, the fine particles of the filler do not move to the polymer member, and the polymer member is not scraped by the fine particles of the filler. It is possible to prevent the characteristics of the temperature sensitive element from changing due to combustion. Therefore, a change in the characteristics of the temperature sensitive element can be prevented for a long time.

  Further, in the temperature sensor according to claim 1, the position where the stopper member is arranged is limited as long as the stopper member can prevent the pulverized filler from moving to the arrangement position of the polymer member in the metal housing member. However, as described in claim 2, the stopper member may be formed as a partition that divides the interior of the metal housing member into a space on the temperature sensing element side and a space on the lead wire side.

According to such a temperature sensor, since the stopper member functions as a partition wall, the finely pulverized filler can be prevented from passing to the lead wire side.
Further, in the temperature sensor according to claim 2, the stopper member is configured to support the sheath member while surrounding the radially outer side of the tubular member of the sheath member inside the metal housing member as described in claim 3. May be.

  According to such a temperature sensor, since the stopper member surrounds the sheath member and supports the sheath member, the sheath member is vibrated while preventing the pulverized filler fine particles from moving to the lead wire side. Can be difficult. Therefore, the sheath member can be made difficult to resonate, and the vibration resistance of the temperature sensor can be improved.

Moreover, since the vibration of the sheath member can be suppressed according to the present invention, the filler can be made difficult to be pulverized even when the temperature sensor is vigorously vibrated.
Further, in the temperature sensor according to any one of claims 1 to 3, as described in claim 4, the outer periphery of the portion of the metal tube in which the cylindrical member of the sheath member is accommodated is opposed to 2. The metal tube and the sheath member may be swaged and fixed by caulking the portion toward the cylindrical member.

  According to such a temperature sensor, the distal end portion of the sheath member can be made difficult to vibrate, so that vibration applied to the temperature sensitive element can be suppressed. In addition, since the vibration of the sheath member can be suppressed according to the present invention, the filler can be made difficult to be crushed.

  In particular, if the present invention (Claim 4) is applied to the temperature sensor according to Claim 3, the sheath member can be supported at both ends, so that the resonance frequency of the sheath member can be increased, The sheath member can be made difficult to resonate. Therefore, the vibration applied to the temperature sensing element can be further suppressed, the vibration resistance of the temperature sensor can be improved, and the connection line between the temperature sensing element and the metal core wire of the sheath member can be prevented from being disconnected. .

  In the present invention, as a polymer member made of a polymer material and housed in the metal housing member so as to cover the periphery of the rear end portion of the lead wire or the metal core wire, the lead wire is taken from the inside of the metal housing member. Covers the periphery of each of a pair of metal core wires, and the metal core wires are in contact with each other, with a seal member made of rubber or the like that seals the opening on the rear end side of the metal storage member while having a lead wire insertion hole for leading to the outside Specific examples include an insulating tube made of a resin or the like that prevents this. In addition, the metal core wire of the sheath member is not limited to a configuration that is directly connected to the temperature-sensitive element and the lead wire, and may be indirectly connected via a conductive member such as a relay terminal.

The preferred embodiments of the present invention will be described below.
[Outline of temperature sensor 1]
FIG. 1 is a partially broken sectional view showing a structure of a temperature sensor 1 according to an embodiment of the present invention. FIG. 2 is a partially broken sectional view showing the front end side and the rear end side of the temperature sensor 1 in an enlarged manner.

  As shown in FIGS. 1 and 2, the temperature sensor 1 supports a sheath member 108 that insulates and holds a pair of metal core wires 7, a cylindrical metal tube 114 that extends in the axial direction with a distal end closed, and the metal tube 114. And a nut member 205 having a hexagonal nut portion 251 and a screw portion 252. In addition, on the rear end side of the attachment member 304, a metallic tubular joint member 6 that accommodates the rear end side of the sheath member 108 therein is provided. The axial direction is the longitudinal direction of the temperature sensor and corresponds to the vertical direction in FIGS. 1 and 2. Moreover, the front end side in the temperature sensor 1 is a lower side in the figure, and the rear end side in the temperature sensor 1 is an upper side in the figure.

  The temperature sensor 1 includes the thermistor element 2 as a temperature sensing element inside the metal tube 114. For example, the temperature sensor 1 is attached to an exhaust pipe, and the thermistor element 2 is placed in a flow pipe through which a measurement target gas (exhaust gas) flows. It can arrange | position and can be used for the temperature detection of measurement object gas. The thermistor element 2 includes a temperature sensing part (thermistor sintered body) 9 whose electrical characteristics (electrical resistance value) change with temperature, and a pair of electrodes for taking out the change in electrical characteristics of the temperature sensing part 9. It is composed of the line 3.

  The metal core wire 7 has a leading end connected to the electrode wire 3 of the thermistor element 2 by welding, and a trailing end connected to an external circuit (for example, an electronic control unit (ECU) of a vehicle) by welding. It is connected to a crimping terminal 11 to which 12 is connected.

  The rear end portions of the pair of metal core wires 7 and the crimping terminals 11 connected thereto are each covered with an insulating tube 15 made of resin (for example, PTFE). The lead wire 12 is obtained by coating a conductive wire with an insulating coating material. The lead wire 12 is disposed in a state of penetrating through a lead wire insertion hole provided in an auxiliary ring 13 made of heat-resistant rubber (for example, fluorine rubber or silicon rubber).

  The sheath member 108 electrically insulates between the metal outer cylinder (not shown), the pair of metal core wires 7 made of a conductive metal, and the outer cylinder and the two metal core wires 7 to form the metal core wire 7. And an insulating powder (not shown) for holding.

  The metal tube 114 is made of a corrosion-resistant metal (for example, a stainless alloy such as SUS310S which is also a heat-resistant metal), and has a cylindrical shape extending in the axial direction in which the tube tip side 131 is closed by deep drawing of the steel plate. The tube rear end side 132 is configured to be open. The metal tube 114 has a tube rear end side 132 fixed to the inside of the second step portion 46 of the attachment member 304.

  The metal tube 114 accommodates the thermistor element 2, the distal end side of the tubular member of the sheath member 108, and the cement 110. The cement 110 fills the periphery of the thermistor element 2, and thereby the thermistor element 2 is shaken. To prevent movement. In addition, the metal tube 114 has a small diameter portion 57 with a small diameter set at the tip portion, and a large diameter portion 58 with a diameter set larger than the small diameter portion 57 at the rear end side. Further, the small diameter portion 57 and the large diameter portion 58 are connected by a step portion 55. The cement 110 is made of an insulating material containing amorphous silica and alumina aggregate.

The attachment member 304 includes a protruding portion 341 that protrudes radially outward, and a rear end-side sheath portion 42 that is located on the rear end side of the protruding portion 341 and extends in the axial direction.
The attachment member 304 supports the metal tube 114 by surrounding the outer peripheral surface on the rear end side of the metal tube 114 with at least the tip of the metal tube 114 exposed to the outside.

  The projecting portion 341 is formed in an annular shape having a mounting seat 345 having a tapered shape with a reduced diameter toward the distal end side. The mounting seat 345 has a tapered shape corresponding to a taper portion having a diameter increasing toward the rear end side at a sensor mounting position of an exhaust pipe (not shown).

  That is, when the attachment member 304 is disposed at the sensor attachment position of the exhaust pipe, the attachment seat 345 is in close contact with the tapered portion of the sensor attachment position, thereby preventing the exhaust gas from leaking outside the exhaust pipe. It is configured to

  The rear end side sheath portion 42 is formed in an annular shape, and includes a first step portion 44 located on the front end side and a second step portion 46 having an outer diameter smaller than that of the first step portion 44. It has a shape. Among these, the second step portion 46 is set to have a thin thickness dimension (diameter difference between the annular inner diameter dimension and the outer diameter dimension) so that deformation by caulking is possible.

  Further, a metallic tubular joint member 6 is joined to the outer side in the radial direction of the first step portion 44 of the rear end side sheath portion 42 in the attachment member 304. The joint member 6 accommodates the rear end side of the sheath member 108 protruding from the tube rear end side 132 of the metal tube 114, the stopper member 30, the crimping terminal 11, the insulating tube 15, the lead wire 12, and the auxiliary ring 13 inside. It is assumed that

  Here, the stopper member 30 is made of, for example, a metal (inorganic material) such as SUS, and is formed integrally with the cylindrical stopper large-diameter portion 31 and the stopper large-diameter portion 31, and the stopper large-diameter portion. And a stopper small-diameter portion 32 having a cylindrical shape whose outer diameter is set smaller than 31.

  The outer diameter of the stopper large diameter portion 31 is set to a dimension that substantially matches the inner diameter of the joint member 6, and the inner diameters of the stopper large diameter portion 31 and the stopper small diameter portion 32 substantially match the outer diameter of the sheath member 108. Set to dimensions.

That is, the stopper member 30 seals a part of the space 37 formed by the difference in diameter between the inner diameter of the joint member 6 and the outer diameter of the tubular member of the sheath member 108.
The stopper member 30 is provided with the stopper small-diameter portion 32 having a smaller outer diameter than the stopper large-diameter portion 31 in order to make this portion easily deformable by setting the thickness of the stopper small-diameter portion 32 thin. It is.

  That is, when the stopper member 30 is arranged inside the joint member 6, the stopper member 30 and the sheath member 108 are once fixed. At this time, the stopper small diameter portion 31 is easily deformed by crimping the stopper small diameter portion 31 radially inward. As a result, the stopper small-diameter portion 32 and the tubular member of the sheath member 108 come into close contact with each other, and the stopper member 30 and the sheath member 108 are positioned and fixed satisfactorily.

  Thus, when the temperature sensor 1 is used in an environment where vibration is vigorously applied, even if the cement 110 is pulverized by vibration, the fine particles of the pulverized cement 110 are separated from the stopper member 30 and the sheath member 108 ( Specifically, it is possible to prevent movement to the auxiliary ring 13 and the insulating tube 15 through the space between the sheath member 108 and the cylindrical member).

  Next, the joint member 6 is caulked inward in the radial direction at the portion where the stopper large-diameter portion 31 of the stopper member 30 is disposed (for example, round caulking), whereby the caulking portion 33 is formed. Yes. As the joint member 6 is crimped radially inward in this manner, the joint member 6 and the stopper large-diameter portion 31 are in close contact with each other, and the joint member 6 and the stopper member 30 are positioned and fixed. When the joint member 6 is crimped in this way, the stopper large diameter portion 31 is slightly deformed radially inward, and the stopper large diameter portion 31 is in a state of sandwiching the sheath member 108.

  Thereby, when the temperature sensor 1 is used in an environment where vibration is vigorously applied, even if the cement 110 is pulverized by vibration, the fine particles of the pulverized cement 110 are separated from the stopper member 30 and the joint member 6. The movement to the auxiliary ring 13 and the insulating tube 15 can be prevented.

  As described above, in the temperature sensor 1, the stopper member 30 is provided in the joint member 6 at a position closer to the distal end side than the auxiliary ring 13 and the insulating tube 15 (that is, the stopper member 30 is provided). The inside of the joint member 6 is formed as a partition wall that separates the space on the thermistor element 2 side and the space on the lead wire 12 side). It is possible to prevent the molecular member from being scraped off. As a result, in the temperature sensor 1 of the present invention, it is possible to effectively prevent a phenomenon such as a change in the characteristics of the thermistor element 2 due to a large amount of combustion of the polymer material inside the joint member 6.

[Method for Manufacturing Temperature Sensor 1]
Here, a manufacturing method of the temperature sensor 1 will be described.
In order to manufacture the temperature sensor 1 of the present embodiment, an operation of assembling the metal tube 114, the sheath member 108, the attachment member 304, and other components that are formed in advance with each other is performed. When assembling each component, first, the thermistor element 2 is welded to the metal core wire 7 of the sheath member 108.

Subsequently, the sheath member 108 to which the thermistor element 2 is welded and the metal tube 114 to which the attachment member 304 is welded are assembled.
That is, a nozzle is inserted into the tip portion of the metal tube 114 to which the mounting member 304 is welded in a state where the thermistor element 2 is not inserted, and the paste cement 110 is injected from the tip of the nozzle.

  Then, the sheath member 108 to which the thermistor element 2 is welded is inserted into the metal tube 114 into which the cement 110 has been injected. At this time, the distal end of the cylindrical member of the sheath member 108 contacts the stepped portion 55 of the metal tube 114.

  Then, with the sheath member 108 inserted into the metal tube 114, long hole caulking is performed in which a plate-shaped mold is pressed against the metal tube 114 from the outside in the radial direction. The long hole caulking is performed on the large-diameter portion 58 on the rear end side of the stepped portion 55 in the metal tube 114 and at two opposing positions on the outer periphery of the large-diameter portion 58. As a result of the caulking, the sheath member 108 is held between the metal tube 114, and the metal tube 114 and the sheath member 108 are positioned and fixed. At this time, the long hole crimping portion 56 is formed in the metal tube 114. With this configuration, vibration on the distal end side of the sheath member 108 can be suppressed, so that the cement 110 can be made difficult to be crushed. Further, since the sheath member 108 is supported at both ends by the stopper member 30 and the elongated hole crimping portion 56, the resonance frequency of the sheath member 108 can be increased, and the sheath member 108 is hardly resonated. Can do. As a result, disconnection of the connection line between the lead wire 12 and the thermistor element 2 (electrode wire 3) can also be prevented. This caulking work may be performed over the entire circumference of the metal tube 114.

  Then, this component is heat-treated at 800 ° C., and the cement 110 is dried (cured) to obtain a tip component composed of the sheath member 108, the attachment member 304, the metal tube 114, and the like.

Next, this tip part and other parts are assembled.
That is, with the stopper member 30, the crimping terminal 11, the lead wire 12, the insulating tube 15, and the auxiliary ring 13 assembled to the tip part, the joint member 6 covers them, and is stored inside the joint member 6. To do. At this time, the stopper member 30 is assembled to the tubular member of the sheath member 108 prior to other components.

  Then, the joint member 6 is press-fitted into the outer periphery of the first step portion 44 of the rear end side sheath portion 42 and laser-welded to the first step portion 44 in the circumferential direction. By performing this laser welding, a joint welding portion 61 is formed across the first step portion 44 of the rear end side sheath portion 42 and the joint member 6. Next, bending is performed at the position on the distal end side of the stopper member 30 in the joint member 6 to form the bent portion 35. By this bending process, the sheath member 108 is also bent together with the joint member 6.

  In the joint member 6, portions corresponding to the stopper member 30 and the auxiliary ring 13 are rounded inward in the radial direction, and the auxiliary ring 13 and the stopper member 30 are fixed in close contact with the joint member 6. The

Next, the nut member 205 is rotatably fitted around the joint member 6 to complete the temperature sensor 1.
The temperature sensor 1 is a screw in which the screw portion 252 of the nut member 205 is formed around the sensor mounting position after the mounting seat 345 of the mounting member 304 is disposed so as to contact the tapered surface of the sensor mounting position. By being screwed into the groove, it is fixed at the sensor mounting position. The external circuit connected to the temperature sensor 1 via the lead wire 12 takes out the electrical characteristics of the thermistor element 2 that changes according to the temperature of the object to be measured. Detect temperature. Thus, the temperature sensor 1 is used for temperature detection by being connected to an external circuit.

  In the present embodiment, the cement 110 corresponds to a filler. Further, the thermistor element 2 corresponds to a temperature-sensitive element in the present invention, and the joint member 6 corresponds to a metal housing member. Further, the auxiliary ring 13 and the insulating tube 15 correspond to a polymer member in the present invention, and the outer cylinder of the sheath member 108 corresponds to a cylindrical member.

The embodiment of the present invention is not limited to the above-described embodiment, and can take various forms as long as it belongs to the technical scope of the present invention.
For example, in the present embodiment, the stopper member 30 is disposed so as to seal the gap between the sheath member 108 and the joint member 6, but the fine particles of the cement 110 that are generated when the cement 110 is crushed are the auxiliary ring 13 and the insulating tube 15. As long as the movement of the stopper member 30 can be suppressed, the arrangement and shape of the stopper member 30 are not particularly limited.

  In the present embodiment, the stopper member 30 is crimped to the tubular member of the sheath member 108 and the joint member 6, but is fixed to each member by welding (for example, laser welding). Also good. Furthermore, the stopper member 30 is not limited to metal, and may be made of a ceramic member such as alumina.

It is a fragmentary sectional view which shows the structure of the temperature sensor which is embodiment of this invention. FIG. 3 is a partially broken cross-sectional view showing an enlarged front end side and rear end side of a temperature sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Temperature sensor, 2 ... Thermistor element, 6 ... Joint member, 7 ... Metal core wire, 11 ... Clamping terminal, 12 ... Lead wire, 13 ... Auxiliary ring, 15 ... Insulating tube, 30 ... Stopper member, 31 ... Large stopper Diameter portion, 32 ... Small diameter portion of stopper, 33 ... Clamping portion, 35 ... Bending portion, 37 ... Space, 42 ... Rear end side sheath portion, 44 ... First step portion, 46 ... Second step portion, 55 ... Step portion 56 ... Long hole crimping part, 57 ... Small diameter part, 58 ... Large diameter part, 61 ... Joint welding part, 108 ... Sheath member, 110 ... Cement, 114 ... Metal tube, 131 ... Tube tip side, 132 ... After tube End side, 205 ... nut member, 251 ... hexagon nut portion, 252 ... screw portion, 304 ... mounting member, 341 ... projecting portion, 345 ... mounting seat, 363 ... rear end side welded portion.

Claims (4)

A temperature sensitive element whose electrical characteristics change with temperature,
In a state in which the temperature sensing element is connected to the front end portion and a pair of metal core wires to which a lead wire for connecting an external circuit is connected to the rear end portion, and the front end portion and the rear end portion of the metal core wire protrude. A sheath member having a cylindrical member for insulatingly holding the metal core wire;
A metal tube that extends in the axial direction, has a cylindrical shape with the distal end closed, and houses the temperature sensitive element and the distal end side of the cylindrical member of the sheath member inside;
An attachment member that surrounds the radially outer side of the metal tube in a form in which the rear end side of the sheath member is projected;
A cylindrical metal storage member that is joined to the outside in the radial direction of the attachment member and that stores the rear end side of the sheath member;
A polymer member made of a polymer material and housed in the metal housing member so as to cover the periphery of the rear end portion of the lead wire or the metal core wire;
A filler filled in the metal tube so as to cover at least the temperature sensitive element;
A temperature sensor comprising:
A space formed by the difference in diameter between the inner diameter of the metal storage member and the outer diameter of the tubular member of the sheath member is located on the tip side of the inside of the metal storage member with respect to the portion where the polymer member is disposed . A member for blocking the passage of fine particles produced by crushing the filler by sealing a part thereof , formed in a cylindrical shape, an outer diameter portion abutting on the metal housing member, and A small-diameter portion having an outer diameter portion smaller than the large-diameter portion and an inner-diameter portion abutting against the tubular member of the sheath member, and a metal stopper member configured integrally,
The small diameter portion of the stopper member and the tubular member of the sheath member are fixed by caulking or welding , and the large diameter portion of the stopper member and the metal storage member are fixed by caulking or welding . Temperature sensor. The temperature sensor according to claim 1, wherein the stopper member is formed as a partition wall that divides the interior of the metal housing member into a space on the temperature sensitive element side and a space on the lead wire side.   The temperature sensor according to claim 2, wherein the stopper member supports the sheath member while surrounding a radially outer side of the tubular member of the sheath member inside the metal housing member. The metal tube and the sheath member are clamped and fixed by crimping two opposing portions of the outer periphery of the portion of the metal tube in which the cylindrical member is housed toward the cylindrical member. The temperature sensor according to any one of claims 1 to 3, wherein the temperature sensor is provided.

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