JP2006234632A - Temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature sensor capable of suppressing the fluctuations of the resistance value of a metal resistor, and suppressing the breakage of a thermosensitive element. <P>SOLUTION: In the second temperature sensor 101, since the thermosensitive element 2 is provided inside a metal tube 114, the thermosensitive element 2 is not brought directly into contact with a measuring object (exhaust gas), to thereby suppress deterioration of the metal resistor 415 due to the influence of the measuring object. A ceramic substrate 414, a ceramic coating layer 417 and a bonding layer 416 of the thermosensitive element 2 are constituted of a material having the alumina purity of 99.9% or higher and has superior migration-proof properties. In the second temperature sensor 101, since the thermosensitive element 2 is provided inside the metal tube 114, waterdrops or the like will not adhere directly to the thermosensitive element 2, to thereby suppress breakages, such as crack generation of the thermosensitive element 2 due to deviations of a temperature distribution generated by waterdrop adhesion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a temperature sensor used in an exhaust system of an internal combustion engine (for example, an automobile engine).

  Conventionally, as a temperature sensor used in an exhaust system of an internal combustion engine (for example, an automobile engine), a temperature sensor including a temperature sensing element having a metal resistor (such as a platinum resistor) is known. This temperature sensor detects the temperature of an object to be measured (such as a gas to be measured) using a change in the electrical resistance value of the temperature sensing element due to a temperature change.

And the temperature sensor is comprised so that a temperature sensing element may touch a to-be-measured object (measuring gas etc.) directly (refer FIG. 4 of patent document 2).
However, when such a temperature sensor is used in a high temperature environment, the metal resistor may be deteriorated due to the influence of the object to be measured and the environmental atmosphere, and as a result, the electric resistance value as the temperature sensing element changes. Thus, an error may occur in temperature detection.

With respect to such a problem, in Patent Document 1, a temperature sensitive element having a structure in which a metal resistor formed on an insulating substrate is covered with glass or the like to prevent contact between the metal resistor and outside air. Is disclosed. According to this temperature sensitive element, the problem of deterioration of the metal resistor can be solved.
Excerpt from US Pat. No. 4050052 Japanese translation of PCT publication No. 2002-514310

  However, even if the temperature sensing element is made of a metal resistor coated with glass, if it is used in a high temperature environment, migration occurs due to the components contained in the glass of the temperature sensing element, and the electrical resistance value as the temperature sensing element. There is a possibility that the problem of fluctuation will occur. For this reason, when a temperature sensor having a temperature sensing element using glass is used in a high temperature environment, there is a possibility that a detection error may occur due to fluctuations in the electric resistance value of the temperature sensing element.

  Some glasses have a heat-resistant temperature of about 1000 ° C. However, since such glass has extremely high silica purity, the thermal expansion coefficient differs from that of an insulating substrate (ceramic substrate). For this reason, the temperature sensitive element using such glass has a possibility that it may be damaged by the difference of the thermal expansion coefficient of glass and a ceramic base | substrate, and there exists a problem that the heat resistance performance as the whole temperature sensitive element falls.

  On the other hand, in order to make the thermal expansion coefficients of the glass and the ceramic substrate equal, it is necessary to use a glass in which a component other than silica is mixed. When it is used at a high temperature environment, migration may occur due to glass components. For this reason, in the temperature sensor of the use which may be exposed to the environment over 950 degreeC, the temperature sensitive element which has glass cannot be used.

  It is also conceivable that the temperature sensitive element is configured using ceramics instead of glass as a material covering the metal resistor. However, if glass components (silica, alkaline earth metal, etc.) are contained in the ceramic itself or the ceramic bonding layer that joins the ceramic and the metal resistor, these components cause migration and the temperature sensitive element. Will induce fluctuations in the electrical resistance.

  In addition, it is difficult to hermetically cover a metal resistor with ceramics. If a temperature sensing element with a metal resistor covered with ceramics is directly touched to the object to be measured, it is attached to the temperature sensor. Will deteriorate.

  On the other hand, in a temperature sensor having a structure in which the temperature sensing element is in direct contact with the object to be measured, water droplets or the like adhere to the temperature sensing element, which may cause local temperature distribution to be biased, resulting in damage such as cracks. is there.

  And the exhaust gas of an internal combustion engine may contain a water | moisture content (condensed water), and there exists a possibility that the thermosensitive element may be damaged by the adhesion of such a water | moisture content. For this reason, the conventional temperature sensor has a problem of lack of reliability when used for temperature detection in an exhaust system of an internal combustion engine.

  Therefore, the present invention has been made in view of these problems, and an object thereof is to provide a temperature sensor that can suppress fluctuations in the resistance value of a metal resistor and can prevent damage to a temperature sensitive element.

  In order to achieve this object, the invention according to claim 1 is characterized in that a film-like metal resistor is formed on a ceramic substrate and a surface of the metal resistor opposite to the surface in contact with the ceramic substrate. In which the ceramic substrate and the ceramic coating layer have an alumina purity, and a temperature-sensitive element having a ceramic coating layer covering the metal resistor, and a bottomed cylindrical element housing member that is open at the rear end side and closed at the front end side. 99.9% or more, and the temperature sensitive element is housed in the end of the element accommodating member on the closed side, and is disposed inside the element accommodating member in a state of being in contact with the temperature sensitive element and the element accommodating member. It is a temperature sensor characterized by including an element fixing material.

  In this temperature sensor, since the temperature sensing element is provided inside the element housing member, the temperature sensing element does not directly contact the object to be measured (measured gas, etc.), and the metal resistor is affected by the object to be measured. Can be prevented from deteriorating. Examples of the metal resistor include a platinum resistor mainly composed of platinum (Pt).

  Further, the ceramic substrate and the ceramic coating layer of the temperature sensitive element are configured with an alumina purity of 99.9% or more, and migration can be suppressed from being caused by components other than alumina contained in the ceramic substrate and the ceramic coating layer.

  In other words, this temperature sensor can suppress the deterioration of the metal resistor due to the influence of the object to be measured, and the temperature sensing element itself has excellent migration resistance, so that the electrical resistance of the temperature sensing element can be used even in a high temperature environment. The value is less likely to fluctuate, and a decrease in temperature detection accuracy can be suppressed.

  In addition, since the temperature sensitive element is supported by the element accommodating member via the element fixing member, it is possible to prevent a collision between the temperature sensitive element and the element accommodating member even in a usage environment that easily receives external force such as vibration. It is possible to prevent damage to the temperature sensing element due to collision with the head and damage due to repeated stress due to impact and vibration.

  In addition, since the temperature sensing element is provided inside the element housing member, water droplets do not directly adhere to the temperature sensing element, thus preventing damage such as cracks caused by uneven temperature distribution due to water droplet adhesion. it can.

  Therefore, according to the present invention, it is possible to suppress fluctuations in the resistance value of the metal resistor, to suppress a decrease in temperature detection accuracy, and to prevent damage to the temperature sensitive element even in a use environment where water droplets or the like are likely to adhere. be able to.

  Next, in the above temperature sensor, the temperature sensitive element is stored in the storage tip portion located on the tip side of the element housing member, and the inner diameter of the storage tip portion is larger than the inner diameter of the other portion of the element housing portion. Also, the diameter should be small.

  In other words, by making the inner diameter of the storage tip where the temperature sensitive element is disposed in the element accommodating member smaller than the inner diameter of the other part, the distance from the inner surface of the element accommodating member to the temperature sensitive element is reduced, and The heat conduction time from the measurement object to the temperature sensitive element can be shortened.

Therefore, according to the temperature sensor of the present invention, the time required for temperature detection can be shortened, and responsiveness in temperature detection can be improved.
Next, in the above-described temperature sensor, the temperature sensitive element is stored in the storage distal end portion located on the distal end side of the element accommodating member, and the thickness dimension of the storage distal end portion is equal to that of the other element accommodating portion. It may be smaller than the thickness dimension.

  That is, regarding the thickness dimension (thickness) from the outer surface to the inner surface of the element housing member, by making the thickness of the storage tip portion where the temperature sensitive element is arranged thinner than the thickness of the other part, The distance from the outer surface of the element housing member to the temperature sensitive element is reduced, and the heat conduction time from the object to be measured to the temperature sensitive element can be shortened.

Therefore, according to the temperature sensor of the present invention, the time required for temperature detection can be shortened, and responsiveness in temperature detection can be improved.
Next, in the above temperature sensor, the cross-sectional shape of the element housing member at the position where the temperature-sensitive element is arranged is a polygon or an ellipse among the cross sections perpendicular to the direction from the closing side to the opening side. Good.

  Thus, in the case where the cross-sectional shape of the portion of the element housing member where the temperature sensitive element is provided is a polygon or an ellipse, compared to the case where the cross-sectional shape is a circular shape, in the internal cross section of the element housing member The occupation ratio of the temperature sensitive element can be relatively increased. That is, in this temperature sensor, the average distance between the inner surface of the element housing member and the outer surface of the temperature sensing element can be reduced, and the heat conduction time from the object to be measured to the temperature sensing element can be shortened. .

  Therefore, according to the temperature sensor of the present invention, the time required for temperature detection can be shortened, and responsiveness in temperature detection can be improved.

The preferred embodiments of the present invention will be described below.
In addition, this invention is not limited to the following embodiment at all, and it cannot be overemphasized that various forms may be taken as long as it belongs to the technical scope of this invention.

FIG. 1 is a partially broken sectional view showing a structure of a temperature sensor 1 according to an embodiment of the present invention.
The temperature sensor 1 includes a sheath member 8 that insulates and holds a pair of metal core wires 7, a bottomed cylindrical metal cap 14 that is closed in the front end side and opened in the rear end side, and an attachment that supports the sheath member 8. And a member 4. The axial direction is the longitudinal direction of the temperature sensor 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 includes a temperature sensing element 2 having a platinum resistor inside the closed end (tip end) of the metal cap 14, and is attached to, for example, a flow pipe (exhaust pipe or the like) of an internal combustion engine. Then, the temperature sensing element 2 can be used for detecting the temperature of the measurement target gas by arranging the temperature sensing element 2 in the flow pipe through which the measurement target gas (exhaust gas or the like) flows. That is, the temperature sensor 1 corresponds to a so-called vehicle temperature sensor. The temperature sensitive element 2 changes its electrical characteristics (electric resistance value) depending on the temperature.

  FIG. 2 is a plan view showing the appearance of the temperature sensing element 2, and FIG. 3 is a cross-sectional view of the temperature sensing element 2 in FIG. In FIG. 2, a part of the internal structure of the temperature sensitive element 2 is indicated by a dotted line.

  The temperature sensing element 2 includes a ceramic substrate 414 having an alumina purity of 99.9%, a metal resistor 415 formed in a film shape on the surface of the ceramic substrate 414, and a surface of the metal resistor 415 that contacts the ceramic substrate 414. And a ceramic coating layer 417 having an alumina purity of 99.9% that covers the metal resistor 415 on the opposite surface.

The metal resistor 415 is mainly composed of platinum (Pt), and the electric resistance value changes according to the temperature change.
The ceramic coating layer 417 is a fired sheet obtained by firing a ceramic green sheet in advance, and is bonded to the front end side (left side in FIG. 3) of the fired ceramic substrate 414 by the bonding layer 416. The metal resistor 415 is provided so as to cover the tip side.

  The bonding layer 416 is also configured with an alumina purity of 99.9%. The bonding layer 416 is a paste containing alumina powder before bonding, and the bonded ceramic base 414 and the ceramic coating layer 417 are bonded to each other with the paste and then heat-treated, whereby the bonding is finally performed. Layer 416 is formed.

  The rear end side (the right side in FIG. 3) of the metal resistor 415 is connected to the lead wire 409 via the thick film pad 418, and then the connection portion is fixed by the lead wire fixing material 419. The lead wire 409 is electrically connected.

The temperature sensing element 2 configured in this way is electrically connected to an external device or the like via the lead lead 409.
In FIG. 1, the metal core wire 7 has a leading end connected to the lead wire 409 of the temperature sensitive element 2 and a rear end connected to the crimping terminal 11 by resistance welding. Thereby, the rear end side of the metal core wire 7 is connected to a lead wire 12 for connecting an external circuit (for example, an electronic control unit (ECU) of a vehicle) via the crimping terminal 11.

  The pair of metal core wires 7 are insulated from each other by the insulating tube 15, and the pair of crimping terminals 11 are insulated from each other by the insulating tube 15. 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 the inside of the heat-resistant rubber auxiliary ring 13.

  Although not shown in detail, the sheath member 8 is a metal that electrically insulates between a metal outer cylinder, a pair of metal core wires 7 made of a conductive metal, and the outer cylinder and the two metal core wires 7. And an insulating powder for holding the core wire 7.

The sheath member 8 is heat treated, and an oxide film is formed on the metal surface.
The metal cap 14 is made of a corrosion-resistant metal (for example, stainless steel such as SUS310S or SUS316), has a cylindrical shape extending in the axial direction with the front end side 31 closed, and the cylindrical rear end side 32 is open. It is configured. The metal cap 14 is attached to the distal end side of the sheath member 8 to which the temperature sensitive element 2 is connected, with the cement 17 filled in the distal end side. The cement 17 is composed of an aggregate mainly composed of alumina and a glass component.

  The metal cap 14 is crimped in the circumferential direction and argon-welded (or electron beam welded) in a state where the inner peripheral surface of the rear end side 32 overlaps the outer peripheral surface of the sheath member 8, whereby the sheath member 8 is fixed. The metal cap 14 is also heat-treated, and an oxide film is formed on the inner and outer surfaces of the metal cap 14.

  In addition, the cap welding part 64 straddling the rear end side 32 of the metal cap 14 and the sheath member 8 (specifically, the outer cylinder of the sheath member 8) is formed by the welding operation. Thereby, the internal space of the metal cap 14 is sealed.

  The metal attachment member 4 includes a hexagonal nut portion 51 protruding radially outward, a screw portion 52 having a thread groove, and a rear end side extending from the rear end of the hexagonal nut portion 51 toward the rear end side in the axial direction. And a sheath portion 42. The attachment member 4 includes an attachment seat 45 formed as a distal end surface of the hexagon nut portion 51, a joint portion 43 joined to the sheath member 8 on the distal end side of the attachment seat 45, and the attachment seat 45 and the joint portion 43. And a vibration reinforcing portion 47 surrounding the periphery of the sheath member 8 in the radial direction.

  The attachment member 4 supports the sheath member 8 by surrounding the outer peripheral surface of the sheath member 8 with at least the metal cap 14 and the distal end portion of the sheath member 8 exposed to the outside.

  The attachment member 4 is fixed to a sensor attachment position formed in the flow pipe in a state where an annular seal ring 48 is disposed on the distal end side of the attachment seat 45. At this time, the mounting seat 45 is in contact with the sensor mounting position (sensor mounting surface) indirectly through the seal ring 48 to prevent a gap from being generated between the temperature sensor 1 and the flow pipe, and measurement is performed. Prevent the target gas from leaking outside.

  The joint portion 43 is formed in an annular shape through which the sheath member 8 can be inserted, and surrounds the periphery of the sheath member 8 in the radial direction and is joined to the sheath member 8. Further, the thickness of the joint portion 43 (diameter difference between the annular inner diameter dimension and the outer diameter dimension) is set to be thin so that deformation by caulking is possible.

  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.

  Then, after the sheath member 8 is inserted into the attachment member 4, the attachment member 4 is subjected to a radially inward caulking operation and an argon welding operation (or an electron welding operation) for each of the joint portion 43 and the second step portion 46. By performing the beam welding operation), the sheath member 8 is supported by surrounding the outer peripheral surface of the sheath member 8. That is, the sheath member 8 is fixed to the attachment member 4 by being bonded to the bonding portion 43 and the second step portion 46.

  The welding operation forms a distal end side welded portion 62 straddling the joint portion 43 and the sheath member 8 (specifically, the outer tube of the sheath member 8), and the second step portion 46 and the sheath member 8 (specifically, the details). , The rear end side welding part 63 straddling the outer cylinder of the sheath member 8 is formed.

  The vibration reinforcing portion 47 is formed in an annular shape through which the sheath member 8 can be inserted, and the sheath member 8 is fixed to the attachment member 4 so as to surround the periphery of the sheath member 8 in the radial direction. Limit the range of movement.

  Further, a metal tubular joint member 6 is joined to the mounting member 4 on the radially outer side of the first step portion 44 of the rear end side sheath portion 42. Specifically, the joint member 6 is connected to the first step portion 44 of the rear end side sheath portion 42 so that the outer peripheral surface of the first step portion 44 of the rear end side sheath portion 42 overlaps the inner peripheral surface of the joint member 6. The joint member 6 and the first step portion 44 are laser welded 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.

  The joint member 6 is a state in which the crimping terminal 11, the insulating tube 15, and the auxiliary ring 13 are accommodated therein, and a portion corresponding to the auxiliary ring 13 is circularly or polygonally crimped inward in the radial direction. While maintaining airtightness between the auxiliary ring 13 and the auxiliary ring 13, it is crimped and joined.

  And the external circuit connected to the temperature sensor 1 via the lead wire 12 takes out the electrical characteristic of the temperature sensing element 2 which changes according to the temperature of the measurement object, and measures the measurement object based on the extracted electrical characteristic. Detect the temperature of the gas.

In the present embodiment, the metal cap 14 corresponds to the element housing member in the claims, and the cement 17 corresponds to the element fixing material.
As described above, in the temperature sensor 1, since the temperature sensing element 2 is provided inside the metal cap 14, the temperature sensing element 2 is not in direct contact with the object to be measured (exhaust gas). It is possible to suppress the deterioration of the metal resistor 415 due to the influence of the above.

  Further, the ceramic substrate 414, the ceramic coating layer 417, and the bonding layer 416 of the temperature sensitive element 2 are configured with an alumina purity of 99.9% or higher (99.9% in this embodiment), and are excellent in migration resistance. .

  In other words, the temperature sensor 1 can suppress the deterioration of the metal resistor 415 due to the influence of the object to be measured, and suppress the occurrence of migration due to components other than alumina contained in the ceramic base 414, the ceramic coating layer 417, and the bonding layer 416. Therefore, even when exposed to a high temperature environment (for example, 1000 [° C.]), the electric resistance value of the temperature sensitive element 2 is less likely to fluctuate, and a decrease in temperature detection accuracy can be suppressed.

  Further, since the cement 17 is disposed inside the metal cap 14 in contact with the temperature sensing element 2 and the metal cap 14, the temperature sensing element 2 is supported by the metal cap 14 via the cement 17. Provided. For this reason, even in a usage environment that is susceptible to external forces such as vibration, the temperature sensitive element 2 and the metal cap 14 can be prevented from colliding, and the temperature sensitive element 2 can be prevented from being damaged due to the collision with the metal cap 14. Moreover, since the temperature sensitive element 2 is supported by the metal cap 14 via the cement 17, the relative position of the temperature sensitive element 2 with respect to the metal core wire 7 can be prevented, and the temperature sensitive element 2 and the metal core wire 7 can be prevented from moving. It is possible to prevent the connection part from being disconnected.

  Further, since the temperature sensing element 2 is provided inside the metal cap 14, water drops or the like do not directly adhere to the temperature sensing element 2, so that the temperature sensing element 2 is caused by uneven temperature distribution due to the adhesion of water drops. Damage such as cracking can be suppressed.

  In the above-described embodiment (hereinafter referred to as the first embodiment), the temperature sensor configured to include an element housing member (metal cap) configured to cover the distal end portion of the sheath member has been described. The present invention is not limited to the embodiment.

  Next, as a second embodiment, a second temperature sensor configured to include an element housing member (metal tube) configured to cover all of the portion of the sheath member that is disposed on the tip side of the attachment member will be described. . In addition, the 2nd temperature sensor 101 is provided with the member which has a screw part and a hexagon nut part as a separate body from an attachment member, without a screw part and a hexagon nut part being formed in the attachment member.

FIG. 4 is a partially broken sectional view showing the structure of the second temperature sensor 101.
The second temperature sensor 101 includes a second 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 the distal end closed, and a second attachment member 304 that supports the metal tube 114. And is configured. The second temperature sensor 101 includes a nut member 205 having a hexagonal nut portion 251 and a screw portion 252.

  The second temperature sensor 101 includes the temperature sensing element 2 inside the metal tube 114. For example, the second temperature sensor 101 is attached to an exhaust pipe of an internal combustion engine, and the temperature sensing element 2 is disposed in an exhaust pipe through which exhaust gas flows. Thus, it can be used for temperature detection of exhaust gas. That is, the second temperature sensor 101 corresponds to a so-called vehicle temperature sensor. The temperature sensitive element 2 changes its electrical characteristics (electric resistance value) depending on the temperature.

The temperature sensitive element 2 has the same configuration as that of the first embodiment, and a description thereof is omitted.
The metal core wire 7 has a leading end connected to the lead wire 409 of the temperature sensitive element 2 and a rear end connected to the crimping terminal 11 by resistance welding. Thereby, the rear end side of the metal core wire 7 is connected to a lead wire 12 for connecting an external circuit (for example, an electronic control unit (ECU) of a vehicle) via the crimping terminal 11.

  Similar to the temperature sensor 1, the second temperature sensor 101 includes a crimping terminal 11, an insulating tube 15, a lead wire 12, an auxiliary ring 13, and a joint member 6. Among the constituent members of the second temperature sensor 101, the same constituent members as those of the temperature sensor 1 of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  Although not shown in detail, the second sheath member 108 has the same configuration as that of the sheath member 8 of the first embodiment in that it includes an outer cylinder, a pair of metal core wires 7, and insulating powder. About a dimension, it is the structure set longer than the sheath member 8 of 1st Embodiment.

  The metal tube 114 is made of a corrosion-resistant metal (for example, a stainless alloy such as SUS310S or SUS316), has a bottomed cylindrical shape extending in the axial direction in which the tube distal end side 131 is closed by deep drawing of the steel plate, and has a cylindrical shape. The tube rear end side 132 is configured to be open. The metal tube 114 accommodates the temperature sensing element 2 and the distal end side of the second sheath member 108 on the tube distal end side 131, and the tube rear end side 132 contacts the inner surface of the second step portion 46 of the second attachment member 304. The axial dimension is set so as to touch.

The metal tube 114 is heat-treated, and an oxide film is formed on the inner and outer surfaces.
The metal tube 114 accommodates the temperature sensing element 2 and the same cement 17 as in the first embodiment. The cement 17 is provided around the temperature sensing element 2 so as to be in contact with the temperature sensing element 2 and the metal tube 114, respectively, and prevents the temperature sensing element 2 from swinging.

Further, the metal tube 114 is formed such that the inner diameter dimension of the storage distal end portion 115 where the temperature sensitive element 2 is disposed is smaller than the inner diameter dimension of the other portions.
The second attachment member 304 includes a second protrusion 341 that protrudes radially outward, a second vibration reinforcement 347 that is positioned on the distal end side of the second protrusion 341 and extends in the axial direction, and a second vibration reinforcement 347. And a rear end side sheath portion 42 that is located on the rear end side of the second projecting portion 341 and extends in the axial direction.

  The second mounting 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 2nd protrusion part 341 is formed in the cyclic | annular form which has the 2nd attachment seat 345 used as the taper shape of diameter reduction shape toward the front end side at the front end side. The second mounting seat 345 has a tapered shape corresponding to a tapered 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 second mounting member 304 is disposed at the sensor mounting position of the exhaust pipe, the second mounting seat 345 is in close contact with the tapered portion of the sensor mounting position, so that the exhaust gas leaks out of the exhaust pipe. It is configured to prevent this.

  The second joint portion 343 is formed in an annular shape through which the metal tube 114 can be inserted, and surrounds the circumference of the metal tube 114 in the radial direction and is joined to the metal tube 114. In addition, the second joint portion 343 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.

  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.

  Then, after the metal tube 114 is inserted into the second attachment member 304, the second attachment member 304 is subjected to caulking work and argon welding inward in the radial direction with respect to the second joint part 343 and the second step part 46, respectively. By performing the work (or electron beam welding work), the metal tube 114 is supported by surrounding the outer peripheral surface of the metal tube 114. That is, the metal tube 114 is fixed to the second attachment member 304 by being joined to the second joint portion 343 and the second step portion 46.

  In addition, the 2nd front end side welding part 362 straddling the 2nd junction part 343 and the metal tube 114 is formed by welding operation, and the 2nd rear end side welding part 363 straddling the 2nd step part 46 and the metal tube 114 is formed. It is formed.

  The second vibration reinforcing portion 347 is formed in an annular shape that allows the metal tube 114 to be inserted therein, and the metal tube 114 is fixed to the second attachment member 304 so as to surround the metal tube 114 in the radial direction. The movement range of the metal tube 114 is limited.

  In addition, a cylindrical joint member 6 made of a stainless alloy is joined to the second attachment member 304 on the radially outer side of the first step portion 44 of the rear end side sheath portion 42. Specifically, the joint member 6 is connected to the first step portion 44 of the rear end side sheath portion 42 so that the outer peripheral surface of the first step portion 44 of the rear end side sheath portion 42 overlaps the inner peripheral surface of the joint member 6. The joint member 6 and the first step portion 44 are laser welded 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.

  The joint member 6 is a state in which the crimping terminal 11, the insulating tube 15, and the auxiliary ring 13 are accommodated therein, and a portion corresponding to the auxiliary ring 13 is circularly crimped or polygonally crimped inward in the radial direction. While maintaining airtightness between the auxiliary ring 13 and the auxiliary ring 13, it is crimped and joined.

  After the second mounting member 304 is disposed so that the second mounting seat 345 contacts the tapered surface of the sensor mounting position in a state where the nut member 205 is rotatably fitted around the joint member 6, The screw portion 252 of the nut member 205 is screwed into a screw groove formed around the sensor attachment position, so that the nut member 205 is fixed to the sensor attachment position. That is, the second attachment member 304 is fixed in a state of being sandwiched between the nut member 205 and the tapered surface at the sensor attachment position. In addition, the second mounting member 304 is arranged in the insertion direction at the sensor mounting position by the second mounting seat 345 coming into contact with the tapered surface of the sensor mounting position.

  And the external circuit connected to the 2nd temperature sensor 101 via the lead wire 12 takes out the electrical property of the temperature sensing element 2 which changes according to the temperature of a measuring object, and based on the taken-out electrical property Detect the exhaust gas temperature.

In the present embodiment, the metal tube 114 corresponds to the element housing member in the claims, and the cement 17 corresponds to the element fixing material.
As described above, the second temperature sensor 101 is provided with the temperature sensing element 2 inside the metal tube 114 in the same manner as the temperature sensor 1 described above. Therefore, the temperature sensing element 2 is the object to be measured (exhaust gas). It is the structure which does not touch directly. Further, the ceramic substrate 414, the ceramic coating layer 417, and the bonding layer 416 of the temperature sensitive element 2 are configured with an alumina purity of 99.9% or higher (99.9% in this embodiment), and are excellent in migration resistance. .

  As described above, the second temperature sensor 101 can suppress the deterioration of the metal resistor 415 due to the influence of the object to be measured, similarly to the temperature sensor 1, and the alumina contained in the ceramic base 414, the ceramic coating layer 417, and the bonding layer 416. Since it is possible to suppress the occurrence of migration due to components other than the above, it is possible to suppress a decrease in temperature detection accuracy even when exposed to a high temperature environment (for example, 1000 [° C.]).

  Further, since the cement 17 is disposed inside the metal tube 114 in a state of being in contact with the temperature sensing element 2 and the metal tube 114, and the temperature sensing element 2 is supported by the metal tube 114 via the cement 17, vibration is caused. Even in a usage environment that is susceptible to external force such as the above, it is possible to prevent the temperature-sensitive element 2 from being damaged due to a collision with the metal tube 114. Further, since the temperature sensitive element 2 is supported by the metal tube 114 via the cement 17, the relative position of the temperature sensitive element 2 with respect to the metal core wire 7 can be prevented, and the temperature sensitive element 2 and the metal core wire 7 can be prevented from moving. It is possible to prevent the connection part from being disconnected.

  Further, since the temperature sensing element 2 is provided inside the metal tube 114, water drops or the like do not directly adhere to the temperature sensing element 2, so that the temperature sensing element 2 is caused by uneven temperature distribution due to adhesion of water drops. Damage such as cracking can be suppressed.

Further, the second temperature sensor 101 includes a metal tube 114 in which the inner diameter dimension of the storage distal end portion 115 is formed smaller than the inner diameter dimension of other portions.
Thus, by reducing the inner diameter of the storage tip 115 where the temperature sensing element 2 is arranged in the metal tube 114, the distance from the inner surface of the metal tube 114 to the temperature sensing element 2 is reduced, and the object to be measured Thus, the heat conduction time from the exhaust gas to the temperature sensing element 2 can be shortened.

Therefore, according to the second temperature sensor 101, the time required for temperature detection can be shortened, and responsiveness in temperature detection can be improved.
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, It can take a various aspect.

  For example, element housing members (metal caps, metal tubes, etc.) are not limited to those having a uniform thickness dimension (thickness) from the outer surface to the inner surface. ) May be used.

  FIG. 5 shows an enlarged cross-sectional view of the distal end portion of the second metal tube 214 in which the thickness of the arrangement portion of the thermosensitive element 2 is made thinner than the arrangement portion of the second sheath member 108. In the figure, the second metal tube 214 is shown in a state in which the temperature sensing element 2 and the distal end portion of the second sheath member 108 are accommodated therein.

  In the second metal tube 214, the thickness dimension T1 of the arrangement portion (second storage tip 215) of the temperature sensing element 2 is larger than the thickness dimension T2 of the arrangement portion (rear end side portion) of the second sheath member 108. The distance is set small, and the distance from the outer surface of the second metal tube 214 to the temperature sensitive element 2 becomes small. In the second metal tube 214, the thickness dimension T1 is 0.1 [mm], and the thickness dimension T2 is 0.3 [mm].

  In the temperature sensor including the second metal tube 214, the distance from the object to be measured (in other words, the outer surface of the second metal tube 214) to the temperature sensing element 2 is reduced, and the object from the object to be measured to the temperature sensing element 2 is reduced. Therefore, the time required for temperature detection can be shortened, and the responsiveness in temperature detection can be improved.

Further, the second metal tube 214 is formed such that the inner diameter dimension L1 of the second storage distal end portion 215 where the temperature sensitive element 2 is disposed is smaller than the inner diameter dimension L2 of the other portion.
For this reason, in the temperature sensor including the second metal tube 214, the distance from the inner surface of the second metal tube 214 to the temperature sensing element 2 is reduced, and the heat conduction time from the object to be measured to the temperature sensing element 2 can be shortened. Since the time required for temperature detection can be shortened, responsiveness in temperature detection can be improved.

  The thickness dimension T1 of the second metal tube 214 is not limited to 0.1 [mm]. For example, when the thickness dimension T2 is 0.3 [mm], the thickness dimension T1 Can be set within the range of 0.05 to 0.2 [mm] to improve responsiveness in temperature detection.

  Note that not only the metal tube but also the metal cap is formed such that the thickness dimension T1 of the temperature sensing element arrangement portion (front end side portion) is smaller than the thickness dimension T2 of the other portion (rear end side portion). Or you may employ | adopt the structure which forms the internal-diameter dimension L1 of the front end side part in which a temperature sensing element is arrange | positioned smaller than another part.

  Next, the element housing member is not limited to the circular shape in the cross-sectional shape at the position where the temperature-sensitive element is arranged among the cross-sections perpendicular to the axial direction from the closed side to the open side, and other shapes Can also be taken.

  FIG. 6 is an explanatory diagram showing cross-sectional shapes of three patterns (an elliptical cross-sectional shape, a square cross-sectional shape, and a hexagonal cross-sectional shape) as the cross-sectional shape at the position where the temperature sensing element 2 is disposed in the metal tube 114. In addition, in FIG. 6, the cross-sectional shape of the part corresponded to the BB view cross section in FIG. 5 among metal tubes is shown.

  The cross-sectional shape of the metal tube 114 shown in the cross-sectional pattern 1 is formed in an elliptical cross-sectional shape at the position where the temperature sensing element 2 is arranged, and the cross-sectional shape of the metal tube 114 shown in the cross-sectional pattern 2 is formed in a square cross-sectional shape. The cross section of the metal tube 114 shown in the cross section pattern 3 is formed in a hexagonal cross section.

  These metal tubes 114 are relatively smaller in the internal cross section because the occupation ratio of the cement 17 in the internal cross section of the metal tube 114 is smaller than that of the metal tube having a circular cross section having a circular shape with a constant radial dimension. The occupation ratio of the temperature sensitive element 2 can be increased.

  That is, by using the metal tube 114 whose cross-sectional shape is elliptical or polygonal, the average distance between the inner surface of the metal tube 114 and the temperature sensing element 2 can be reduced. The heat conduction time up to can be further shortened.

Therefore, the temperature sensor including such a metal tube 114 can shorten the time required for temperature detection, and can further improve the responsiveness in temperature detection.
Note that not only the metal tube but also the metal cap can be further improved in responsiveness in temperature detection by forming the cross-sectional shape at the arrangement position of the temperature sensing element into a polygon or an ellipse.

  In the above embodiment, as the temperature sensitive element 2, the ceramic base 414 having an alumina purity of 99.9%, on which the metal resistor 415 is formed, and the ceramic coating layer 417 having an alumina purity of 99.9% are bonded to the bonding layer. The temperature sensing element having a structure joined via 416 was used. However, after placing the fired ceramic coating layer 417 directly on the fired ceramic base 414, the side surfaces of both sheets 414 and 417 were joined at the joint. A thermosensitive element having a bonded structure may be used.

It is a fragmentary sectional view which shows the structure of a temperature sensor. It is a top view showing the external appearance of a temperature sensing element. It is sectional drawing in the AA cross section of the temperature sensing element in FIG. It is a fragmentary sectional view which shows the structure of a 2nd temperature sensor. It is an expanded sectional view of the tip part in the 2nd metal tube. It is explanatory drawing showing cross-sectional shape of 3 patterns as cross-sectional shape in the arrangement position of a temperature sensing element among metal tubes.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Temperature sensor, 2 ... Temperature sensing element, 4 ... Mounting member, 7 ... Metal core wire, 8 ... Sheath member, 14 ... Metal cap, 15 ... Insulating tube, 17 ... Cement, 45 ... Mounting seat, 47 ... Vibration reinforcement part , 64 ... Cap welding part, 101 ... Second temperature sensor, 108 ... Second sheath member, 114 ... Metal tube, 214 ... Second metal tube, 304 ... Second attachment member, 345 ... Second attachment seat, 347 ... First 2 vibration reinforcement parts, 409 ... lead wire, 414 ... ceramic substrate, 415 ... metal resistor, 416 ... bonding layer, 417 ... ceramic coating layer, 418 ... thick film pad, 419 ... lead wire fixing material.

Claims (4)

A thermosensitive element having a ceramic coating layer that covers the metal resistor on a surface of the metal resistor opposite to the surface in contact with the ceramic substrate, wherein a film-like metal resistor is formed on the ceramic substrate When,
A bottomed cylindrical element housing member whose rear end side is open and whose front end side is closed;
The ceramic substrate and the ceramic coating layer are configured with an alumina purity of 99.9% or more,
The temperature sensitive element is stored inside the element housing member,
An element fixing member disposed inside the element housing member in a state of being in contact with the temperature sensitive element and the element housing member,
Temperature sensor. The temperature sensitive element is stored in a storage distal end located on the distal end side of the element accommodating member,
The inner diameter of the storage tip is smaller than the inner diameter of the other part of the element housing;
The temperature sensor according to claim 1. The temperature sensitive element is stored in a storage distal end located on the distal end side of the element accommodating member,
The thickness dimension of the storage tip is smaller than the thickness dimension of the other part of the element housing;
The temperature sensor according to claim 1, wherein: Of the cross section perpendicular to the direction from the closing side to the opening side, the element housing member has a polygonal or elliptical cross-sectional shape at the position where the temperature sensitive element is disposed,
The temperature sensor according to any one of claims 1 to 3, wherein: