JP2007240341A - Temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature sensor capable of suppressing enlargement of a metal pipe without miniaturizing a temperature sensing part, in the temperature sensor where measures are taken against both of a problem wherein an electrode line is disconnected by vibrating the temperature sensor and a problem wherein the resistance value of a thermistor is varied by oxidation of a metal tube at high temperatures. <P>SOLUTION: The inside of the metal tube 114 of the temperature sensor 1 is provided with an insulating/supporting member 100 having a function of supporting a pair of electrode lines 3 and a metal core wire 7 while maintaining a state where one of the electrode lines 3 and the metal core wire 7 is in non-contact with the other of the electrode lines 3 and the metal core wire 7 and a function of containing an oxygen supply material composed of an oxygen supply oxide in a range for keeping the insulating property of itself and releasing oxygen. Thus, the reliable temperature sensor 1 whose enlargement is suppressed and responsiveness to temperature detection does not decrease can be provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a temperature sensor in which a temperature sensing element including a temperature sensing part such as a thermistor made of a semiconductor such as a metal oxide or a metal resistor such as Pt is arranged in a bottomed cylindrical metal tube.

  Conventionally, a temperature sensor S1 as in Patent Document 1 is known as a temperature sensor having a temperature sensitive element. The temperature sensor S1 has a thermistor element 3 (temperature sensing part), an electrode wire 4 connected to the thermistor element 3, a metal core wire 5a connected to the electrode wire 4, and a tip of the metal core wire 5a protruding. And a sheath pin 5 (sheath member) for insulatingly holding the metal core wire 5a. The tip portions of the thermistor element 3, the electrode wire 4, the metal core wire 5a, and the tip portion of the sheath pin 5 are accommodated inside the metal cover 2 (metal tube). Furthermore, with respect to the problem that the electrode wire 4 is disconnected due to vibration applied to the temperature sensor S1, an insulator member 6 (insulating support member) that holds the electrode wire 4 in a non-contact state inside the metal cover 2 is provided. Contained. Specifically, the insulator member 6 has a hole 6a into which the electrode wire 4 is inserted, and the electrode wire 4 is supported by the hole 6a, thereby improving the vibration resistance of the electrode wire 4. .

As conventional temperature sensors, temperature sensors such as Patent Document 2 and Patent Document 3 are also known. This temperature sensor is for the problem that the characteristics of the thermistor change due to oxygen deficiency in the metal tube due to oxidation of the metal tube at high temperature. ) Is disposed in the vicinity of the oxygen releasing ceramic body 2. That is, since the oxygen releasing ceramic body 2 partially releases oxygen when the metal tube is in an oxygen deficient state, it is possible to suppress or alleviate the inside of the metal tube 2 becoming an oxygen-deficient atmosphere.
JP 2002-267547 A JP-A-5-264368 JP 2000-266609 A

  By the way, when a temperature sensor that takes measures against both the problems of Patent Document 1 and Patent Documents 2 and 3 is manufactured, it is necessary to dispose both the insulating support member and the oxygen-releasing ceramic body inside the metal tube. Then, the metal pipe needs a space for arranging both, and the metal pipe itself becomes large, and there is a possibility that it cannot meet the recent demand for downsizing of the temperature sensor. In addition, if a relatively large volume member such as an insulating support member and an oxygen-releasing ceramic body is housed in the metal tube together with the temperature sensing element, heat is less likely to be transmitted to the temperature sensing element via the metal tube. There is also a possibility of decline.

  The present invention has been made in view of such conventional problems, such as a problem that the electrode wire is disconnected due to vibration applied to the temperature sensor, and a problem that the thermistor characteristics change due to oxidation of the metal tube. In taking measures for both of the above, it is an object to provide a temperature sensor that does not increase the size of the metal tube and does not reduce the responsiveness to temperature detection.

  Therefore, the temperature sensor of the present invention is a temperature sensing element having a temperature sensing portion whose electrical characteristics change according to temperature, an electrode wire connected to the temperature sensing portion, and a tip portion connected to the electrode wire, A sheath member having a metal core wire whose rear end portion is connected to a lead wire for connecting an external circuit, and a cylindrical member that insulates and holds the metal core wire in a state where the tip portion of the metal core wire protrudes at least; A metal tube that has a bottomed cylindrical shape with a closed tip and accommodates at least the tip portion of the tube member of the temperature sensing element and the sheath member therein, and at least more than the temperature sensing portion in the metal tube. A pair of a pair of the electrode wire and the metal core wire is located on the rear end side and on the tip end side of the cylindrical member, and maintains one of the electrode wire and the metal core wire in a non-contact state. The electrode wire and the metal core wire In a temperature sensor and an insulating support member for lifting, the insulating support member, characterized in that it contains the oxygenate consisting of oxygen supply oxide to the extent that maintain their insulating properties.

  According to the temperature sensor of the present invention, the inside of the metal tube is in an oxygen deficient state at a high temperature by causing the insulating support member covering at least a part of the periphery of the electrode wire and the metal core wire to contain the oxygen supply substance composed of the oxygen supply oxide. In this case, the insulating support can release oxygen, and the metal tube can be suppressed or alleviated from becoming an oxygen-deficient atmosphere. That is, in the temperature sensor of the present invention, the insulating support member that covers at least a part of the periphery of the electrode wire and the metal core wire has the function of supporting the electrode wire and the metal core wire, and also has the above-described oxygen release function. It is.

  As a result, the conventional oxygen supply ceramic is used to counter both the problem of electrode wire breakage due to vibration applied to the temperature sensor and the problem of thermistor characteristics changing due to metal tube oxidation. Since it is not necessary to dispose the body in the metal tube, it is possible to provide a highly reliable temperature sensor that suppresses an increase in the size of the temperature sensor and does not deteriorate the responsiveness to temperature detection.

  The oxygen supply substance needs to be contained in the insulating support member within a range that maintains the insulating property of the insulating support member. When the insulating support member contains the oxygen supply substance, if the insulating support member becomes conductive, a leak current is generated between the pair of electrode wires or the pair of metal core wires via the insulating support member. This is because the temperature detection may be affected. In addition, in this specification, the range which maintains the insulation of an insulating support member specifically indicates that the insulation resistance of an insulating support member at 900 ° C. is 2.0 KΩ or more. The insulation resistance at 900 ° C. is preferably 2.6 KΩ or more in order to maintain reliable insulation.

Furthermore, in the temperature sensor of the present invention, it is preferable that the oxygen supply substance is at least one of NiO, Fe ₂ O ₃ , and CeO ₂ . NiO, CeO ₂ , CoO, WO ₃ , CuO, Ga ₂ O ₃ , SnO ₂ , Fe ₂ O ₃ , Ta ₂ O ₅ , ZrO _2, etc. can be adopted as the oxygen supply substance, but the oxygen supply substance This is because NiO, Fe ₂ O ₃ and CeO ₂ have particularly high oxygen supply capacity.

  Furthermore, in the temperature sensor of the present invention, it is preferable that the oxygen supply substance is dispersed in the insulating support member. Since the oxygen supply substance is dispersed in the insulating support member in this way, oxygen from the oxygen supply substance can be efficiently released into the metal tube, and the characteristic change of the temperature sensitive part due to oxygen deficiency can be efficiently suppressed. can do.

  Below, the temperature sensor 1 which is 1st Embodiment to which this invention is applied is demonstrated with drawing. FIG. 1 is a partially broken cross-sectional view showing the structure of the temperature sensor 1 of the first embodiment.

  The temperature sensor 1 is joined to the sheath member 108 in which the pair of metal core wires 7 are insulated and held inside the cylinder member 27, the cylindrical metal tube 114 extending in the axial direction with the distal end closed, and the metal tube 114. An attachment member 304 that supports the metal tube 114, a tubular joint member 6 joined to the rear side of the attachment member 304, and a nut member 205 having a hexagon nut 251 and a screw portion 252 are configured. The axial direction is the longitudinal direction of the temperature sensor 1 and corresponds to the vertical direction in FIG. 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 accommodates the thermistor element 2 inside the metal tube 114. The temperature sensor 1 is attached to a flow pipe such as an exhaust pipe of an internal combustion engine, for example, and the thermistor element 2 has a measurement target gas (exhaust gas). It can arrange | position in the flowing flow pipe 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 front end portion connected to the electrode wire 3 of the thermistor element 2 by welding, and a rear end portion connected to the crimping terminal 11 by welding. The crimp terminal 11 is connected to a lead wire 12 for connecting an external circuit (e.g., an electronic control unit (ECU) of a vehicle) on the rear end side of itself. As a result, the change in the electrical characteristics of the temperature sensing unit 9 is extracted to the external circuit via the electrode wire 3, the metal core wire 7, the crimping terminal 11, and the lead wire 12.

  The pair of crimp terminals 11 are insulated from each other by an insulating tube 15. In addition, the lead wire 12 formed by covering a conducting portion obtained by twisting a plurality of conducting wires with an insulating coating material is formed from the inside of the joint member 6 in a state of passing through the inside of the auxiliary ring 13 made of heat-resistant rubber. It is pulled out to the outside. The auxiliary ring 13 is caulked and fixed by the joint member 6.

  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 distal end 131 is closed by deep drawing of the steel plate. The rear end side 132 is open. The axial dimension of the metal tube 114 is set so that the tube rear end side 132 abuts against the inner surface of the second step portion 46 of the attachment member 304.

  The metal tube 114 accommodates the thermistor element 2 and the cement 110 therein, and the cement 110 is filled around the thermistor element 2 to prevent the thermistor element 2 from swinging (see FIG. 2). ). The cement 110 is made of an insulating material containing alumina aggregate in silica. Further, 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 warp set larger than the small diameter portion 57 at the rear end side. The small diameter portion 57 and the large diameter portion 58 are connected by a step portion 55.

  The insulating support member 100 is disposed so as to cover most of the outer periphery on the front end side of the metal core wire 7 and the rear end side of the electrode wire 3. As shown in FIG. 3, the insulating support member 100 has a substantially S-shaped cross section, and is formed such that the first slit 100a and the second slit 100b face in opposite directions. A partition wall 100c is formed between 100a and the second slit 100b. And the electrode wire 3 and the metal core wire 7 of the connected state are hold | maintained in the state inserted in the 1st slit 100a and the 2nd slit 100b, respectively. Thereby, even if vibration is applied to the temperature sensor 1, the partition wall 100c prevents the electrode wires 3 and the metal core wires 7 from contacting each other, and the electrode wires 3 and the metal core wires 7 can be prevented from being disconnected.

  This insulating support member 100 contains NiO that is an oxygen supply oxide in alumina. Thereby, even when the metal tube 114 is exposed to a high temperature of 900 to 1000 ° C. and the metal tube 114 is oxidized, oxygen is released from the insulating support member 100 (specifically, oxygen supply oxide). Therefore, the inside of the metal tube 114 is suppressed or relieved from becoming an oxygen-deficient atmosphere. Therefore, it can suppress that the characteristic of the temperature sensing part 9 changes.

  Returning to FIG. 1, 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 surrounds the outer peripheral surface of the rear end side of the metal tube 114 and supports the metal tube 114 with at least the front end side 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 is formed in a taper 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 mounting member 304 is disposed at the sensor mounting position of the exhaust pipe, the mounting seat 345 is mounted in close contact with the tapered portion of the sensor mounting position, so that exhaust gas leaks out of the exhaust pipe. Is configured to prevent.

  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. And the 2nd step part 46 and the metal tube 114 are welded by the welding part 363. FIG. Further, the first step portion 44 and the distal end portion of the joint member 6 are welded by a welding portion 364.

  The temperature sensor 1 of the first embodiment can be manufactured as follows. That is, the thermistor element 2 in which the electrode wire 3 protrudes from the temperature sensing part 9, the sheath member 108 in which the metal core wire 7 protrudes from the cylindrical member 27, the insulating support member 100 as shown in FIG. 3, and the attachment member 304 are prepared. To do. Then, the electrode wire 3 and the metal core wire 7 are inserted into the first slit 100a and the second slit 100b in the insulating support member 100 by predetermined dimensions, and each is welded by laser welding to connect each other.

  Thereafter, the uncured cement 110 is disposed in the gap between the temperature sensing unit 9 and the insulating support member 100. Specifically, uncured cement 110 is injected and filled into the gap between the temperature sensing unit 9 and the insulating support member 100 using a dispenser (not shown). Next, the cement 110 is solidified. Specifically, the thermosensitive part 9 and the insulating support member 100 are fixed to each other by heating at 900 ° C. for 5 hours to be cured.

  Next, an operation of assembling the metal tube 114 to the attachment member 304 is performed. Specifically, the metal tube 114 is inserted into the attachment member 304, the second step portion 46 is caulked inward in the radial direction, and the metal tube 114 and the attachment member 304 are fixed by laser welding. Thereafter, a predetermined amount of uncured cement 110 is injected into the distal end portion 131 of the metal tube 114, and the temperature sensing portion 9, the insulating support member 100, and the sheath member 108 are inserted into the metal tube 114 in that state. Next, the uncured cement 110 is cured by heat treatment. Then, the temperature sensing unit 9 and the insulating support member 110 are stably held in the metal tube 114 via the cement 110. Thereafter, the temperature sensor 1 is completed using a known temperature sensor manufacturing method such as an operation of attaching the crimping terminal 11 to the metal core wire 7 of the sheath member 108 or an operation of fixing the joint member 6 to the attachment member 304.

  Next, the temperature sensor 400 which is 2nd Embodiment to which this invention is applied is demonstrated with drawing. FIG. 4 is a partially broken cross-sectional view showing the structure of the temperature sensor 400 of the second embodiment. Note that the temperature sensor 400 of the second embodiment is different only in the shapes of the metal tube 114 and the attachment portion 304 of the temperature sensor 1 of the first embodiment, and will be described mainly with respect to the other parts. The description will be simplified or omitted using the same reference numerals.

  The temperature sensor 400 includes a sheath member 108 in which a pair of metal core wires 107 are insulated and held inside the cylindrical member 27, an attachment member 404 that supports the sheath member 108, and a nut member 205 having a hexagon nut 251 and a screw portion 252. It is prepared for. The axial direction is the longitudinal direction of the temperature sensor 400, and corresponds to the vertical direction in FIG. Moreover, the front end side in the temperature sensor 400 is the lower side in the figure, and the rear end side in the temperature sensor 400 is the upper side in the figure.

  The metal cap 414 is made of a corrosion-resistant metal (for example, a stainless alloy such as SUS310S which is also a heat-resistant metal), has a cylindrical shape extending in the axial direction in which the tube tip side 431 is closed by deep drawing of the steel plate, and is a cylindrical tube The rear end side 432 is open. The metal cap 414 has the inner surface of the tube rear end side 432 fixed to the outer surface of the tubular member 27 of the sheath member 108 by welding.

  The metal cap 414 accommodates the thermistor element 2 and the cement 110 therein, and the cement 110 is filled around the thermistor element 2 to prevent the thermistor element 2 from swinging (see FIG. 5). ). The metal cap 414 has a small-diameter portion 457 whose tip portion is set to have a small diameter, and a rear-end side thereof is a large-diameter portion 458 whose warp is set to be larger than the small-diameter portion 457. The small diameter portion 457 and the large diameter portion 458 are connected by a step portion 455.

  And the insulating support member 100 is arrange | positioned so that the outer periphery of the front end side of the metal core wire 7, and the rear end side of the electrode wire 3 may be covered. The insulating support member 100 has a substantially S-shaped cross section, and is formed such that the first slit 100a and the second slit 100b face in opposite directions, and the first slit 100a and the second slit 100b A partition wall 100c is formed between them. And the electrode wire 3 and the metal core wire 7 are hold | maintained in the state inserted in the 1st slit 100a and the 2nd slit 100b, respectively. Thereby, even if vibration is applied to the temperature sensor 1, the partition wall 100 c can prevent the electrode wires 3 and the metal core wires 7 from contacting each other, and the electrode wire 3 and the metal core wire 7 can be prevented from being disconnected.

  This insulating support member 100 contains NiO that is an oxygen supply oxide in alumina. Accordingly, even when the metal cap 414 is exposed to a high temperature of 900 to 1000 ° C. and the metal cap 414 is oxidized, oxygen is released from the insulating support member 100 (specifically, oxygen supply oxide). Therefore, the inside of the metal cap 414 is suppressed or relieved from becoming an oxygen-deficient atmosphere. Therefore, it can suppress that the characteristic of the temperature sensing part 9 changes.

  Returning to FIG. 4, the attachment member 404 includes a protrusion 441 that protrudes outward in the warp direction, and a rear end-side sheath 442 that is located on the rear end side of the protrusion 441 and extends in the axial direction. The attachment member 404 supports the sheath member 108 by surrounding the outer peripheral surface of the sheath member 108 with at least the distal end side of the sheath member 108 exposed to the outside.

  The projecting portion 441 is formed in an annular shape with a mounting seat 445 having a tapered shape with a reduced diameter toward the tip side. The mounting seat 445 is formed in a taper 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 404 is disposed at the sensor attachment position of the exhaust pipe, the attachment seat 445 is attached in close contact with the taper portion of the sensor attachment position, so that the exhaust gas leaks outside the exhaust pipe. Is configured to prevent.

  The temperature sensor of the second embodiment can be manufactured as follows. That is, the thermistor element 2 in which the electrode wire 3 protrudes from the temperature sensing portion 9, the sheath member 108 in which the metal core wire 7 protrudes from the cylindrical member 27, the insulating support member 100, and the attachment member 404 are prepared. Then, the cylindrical member 27 is inserted into the attachment member 404 and fixed. Thereafter, the electrode wire 3 and the metal core wire 7 are inserted into the first slit 100a and the second slit 100b in the insulating support member 100, and each is welded by laser welding to connect each other.

  Thereafter, the uncured cement 110 is disposed in the gap between the temperature sensing unit 9 and the insulating support member 100. Specifically, uncured cement 110 is injected and filled into the gap between the temperature sensing unit 9 and the insulating support member 100 using a dispenser (not shown). Next, the cement 110 is cured. Specifically, the thermosensitive part 9 and the insulating support member 100 are fixed to each other by heating at 900 ° C. for 5 hours to be cured. Thereafter, the temperature sensing unit 9 and the insulating support member 100 are inserted into a metal cap 414 in which a predetermined amount of uncured cement 110 has been injected into the tip 431 of the metal cap 414 in advance. At this time, the temperature sensing unit 9 and the insulating support member 100 are inserted so that the tip of the tubular member 27 of the sheath member 108 is disposed in the metal cap 414. Next, the uncured cement 110 is cured by heat treatment. Then, the temperature sensing unit 9 and the insulating support member 110 are stably held by the cement 110 in the metal cap 414. Thereafter, the tube rear end side 432 of the metal cap 414 is crimped, temporarily fixed to the sheath member 108, and further welded by laser welding, so that the metal cap 414 and the sheath member 108 are fixed. Thereafter, the temperature sensor 400 is manufactured by a known temperature sensor manufacturing method.

  In the first embodiment and the second embodiment, the thermistor element 2 is the temperature-sensitive element in the claims, and the metal tube 114 and the metal cap 414 are the metal tubes in the claims.

Although the first embodiment and the second embodiment of the present invention have been described above, the present invention is not limited to the first embodiment and the second embodiment, and various design changes can be made.
For example, in the first embodiment and the second embodiment, the insulating support member 100 shown in FIG. 3 is used, but an insulating support member as shown in FIG. 6 may be used. Specifically, the insulating support member 500 shown in FIG. 6A is an insulating support member having an E-shaped cross section in which the first slit 500a and the second slit 500b are open in the same direction (upward in the drawing). is there.
In addition, the insulating support member 510 shown in FIG. 6B has an H-shaped insulating support member in which the first slit 510a and the second slit 510b are opened back to back in opposite directions (upward in the figure). It is.
6C includes two members, a first insulating support member 521 and a second insulating support member 522. When these are combined, a cylindrical shape having two holes is formed. It becomes an insulating support member.

  Furthermore, in the first embodiment and the second embodiment, alumina is used as the insulating material of the insulating support member 100, but not limited thereto, for example, silica, mullite, or the like can be used.

  Furthermore, in the first embodiment and the second embodiment, the example in which the thermistor element 2 and the insulating support member 100 are surrounded by the cement 110 has been shown. However, the present invention is not limited thereto, and for example, the temperature sensing unit 9 and the insulating support member 100 are included. It may be a structure in which the cement 110 is disposed only between the gaps (gap).

It is a partial broken sectional view of gas sensor 1 of a 1st embodiment. It is principal part broken sectional drawing of the gas sensor 1 of 1st Embodiment. It is a perspective view of the insulation support member 100 of 1st Embodiment and 2nd Embodiment. It is a partial broken sectional view of gas sensor 400 of a 2nd embodiment. It is principal part fracture | rupture sectional drawing of the gas sensor 400 of 2nd Embodiment. It is a perspective view of the insulation support members 500, 510, and 520 of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,400 ... Temperature sensor 2 ... Thermistor element 3 ... Electrode wire 7 ... Metal core wire 9 ... Temperature sensing part 27 ················································ Cement 114 ·························· Metal caps 100, 500, 510, 520・ Insulation support member

Claims (3)

A temperature sensing element having a temperature sensing part whose electrical characteristics change with temperature, and a pair of electrode wires connected to the temperature sensing part;
A pair of metal core wires whose front end portions are connected to the electrode wires and whose rear end portions are connected to lead wires for external circuit connection, and the metal core wires are in a state where the front end portions of the metal core wires protrude at least. A sheath member having a cylindrical member for insulating and holding;
A bottomed cylindrical shape with a closed tip, and a metal tube that accommodates at least the tip of the tubular member of the temperature sensing element and the sheath member therein;
In the metal tube, at least the rear end side of the temperature sensing portion and the front end side of the cylindrical member, and one of the electrode wire and the metal core wire is the other of the electrode wire and the metal core wire. An insulating support member that supports the pair of electrode wires and the metal core wire so as to maintain a non-contact state;
In a temperature sensor comprising:
The temperature sensor characterized in that the insulating support member contains an oxygen supply substance composed of an oxygen supply oxide within a range that maintains its insulating properties. The temperature sensor according to claim 1, wherein the oxygen supply material is at least one of NiO, Fe ₂ O ₃ , and CeO ₂ . The temperature sensor according to claim 1, wherein the oxygen supply substance is dispersed in the insulating support member.