JP2011128013A - Mounting structure of temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of problems, such as sealing failures or loosening of a screwing state, even in a mounting structure of a temperature sensor used for temperature measurement of high-temperature gas, wherein a mounting screw hole formation portion on which the sensor is mounted has a high thermal expansion coefficient, whereas a circular pressing part or a fixing member for screwing on the sensor side has a relatively low thermal expansion coefficient, because of its being made of SUS, and the compressive stress in the axial direction of the circular pressing part is reduced due to the thermal expansion difference caused by a temperature rise, after bing mounted. <P>SOLUTION: A spacer 51, including a material having a higher thermal expansion coefficient than a material constituting the circular pressing part or the fixing member for screwing, and having a thermal expansion coefficient higher than that of a material forming the mounting screw hole 503, is interposed between the circular pressing part 31 and the fixing member 61 for screwing of the sensor 101. Reduction in the compressive stress, in the axial direction of the circular pressing part 31 in the mounted state can be reduced, by utilizing the thermal expansion of the spacer 51. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a temperature sensor mounting structure for detecting the temperature of a fluid, and more particularly, to mount a temperature sensor for measuring the temperature of a fluid such as an exhaust gas of an engine, provided on an object (for example, an exhaust pipe) through which the fluid passes. The present invention relates to a mounting structure of a temperature sensor (hereinafter also simply referred to as a sensor) attached to a screw hole.

  FIG. 9 is a cross-sectional view showing an example of this type of temperature sensor 201 and its mounting structure. The temperature sensor 201 shown in FIG. 9 is for measuring the temperature of the exhaust gas in the exhaust pipe 500 (exhaust temperature sensor), and is attached to the distal end portion of the tube 11 whose distal end (lower end in the figure) is closed. A temperature sensor element (hereinafter also referred to as a sensor element or simply an element) 21 such as a thermistor is provided and configured as follows. That is, the tube 11 containing the element 21 constituting the sensor 201 includes, for example, an annular pressing portion 31 that protrudes in a flange shape outside the rear end portion. The annular pressing portion 31 is pressed against an annular seating surface 505 for holding a seal at the back of an attachment screw hole (hereinafter also simply referred to as a screw hole) 503 provided in an attachment target portion (boss) 501 of the exhaust pipe 500. For example, it is provided in the tube 11 by welding or press fitting. In addition, a large-diameter tube (protective tube) 41 having a larger diameter than that of the tube 11 containing the element 21 is provided on the outer side of the cylindrical portion that protrudes rearward on the rear end side of the annular pressing portion 31. The tip is fitted externally, and is fixed concentrically so as to extend rearward. Then, behind the flange-shaped annular pressing portion 31, a screw 62 is slidable rearward and externally fitted into the large-diameter tube 41, and can be screwed into the mounting screw hole 503 on the outer peripheral surface. A cylindrical or annular screw fixing member 61 is provided. The electrode wire 23 extending from the element 21 is connected to a core wire 24 disposed in the sheath tube 25, and the core wire 24 is connected to a lead wire 28 for signal extraction from the rear end of the large-diameter tube 41 to the outside. 27 is connected. The lead wire 28 is passed through a seal member 47 disposed in the rear end portion 45 of the large-diameter tube 41, and is fixed by caulking the rear end portion 45 to a reduced diameter.

  In the temperature sensor 201 having such a configuration, the annular pressing portion 31 is provided on the annular seating surface 505 at the back of the attachment screw hole 503 provided in the boss 501 that is the attachment target portion in the exhaust pipe 500 to which the temperature sensor 201 is attached. Is attached by screwing (tightening) the fixing member 61 for screwing into the mounting screw hole 503 from the rear. That is, the annular pressing portion 31 is pressed against the distal end side at the distal end 63 of the screwing fixing member 61, and the annular pressing portion 31 is moved between the screwing fixing member 61 and the annular seating surface 505. (Axis) Compressed in the G direction (front-rear direction), the sensor 201 is attached to the screw hole 503 while holding a seal. In such an attachment structure, the annular pressing portion 31 is strongly compressed in the front-rear direction. Therefore, the fixing member 61 for screwing is similarly held in a compressed state. For this reason, they theoretically shrink in the direction of the axis G in a minute amount corresponding to the compressive stress. On the other hand, the mounting screw hole 503 of the boss 501 provided in the exhaust pipe 500 receives a tensile stress corresponding to the compressive stress in the direction of the axis G, and theoretically extends a small amount corresponding to the tensile stress. . However, with regard to the fixing member 61 for screwing and the mounting screw hole 503, it is considered that the expansion and contraction at the portion where the screw is screwed is negligible. Thus, in the conventional sensor 201 mounting structure, it can be said that the seal is held and the sensor 201 is mounted stably.

  By the way, the sensor 201 used for measuring the temperature of the exhaust gas is normally mounted at room temperature. However, it is exposed to the high temperature due to the heat of the exhaust gas after the mounting. For this reason, the part of the boss 501 of the exhaust pipe 500 to which the sensor 201 is attached, that is, the mounting screw hole 503 and the annular seating surface 505, the annular pressing portion 31 pressed against this, and the fixing for screwing The part near the tip of the sensor 201 including the member 61 is exposed to a high temperature of 200 ° C. to 500 ° C. or higher depending on the attachment target part. Therefore, the annular pressing portion 31 constituting the sensor 201, the fixing member 61 for screwing, and the boss 501 forming the mounting screw hole 503 to which the sensor 201 is attached are formed from materials having different thermal expansion coefficients. In such a case, there is a problem that a seal failure or looseness may occur due to a difference in thermal expansion / contraction amount based on a difference in each thermal expansion coefficient.

For example, the attachment target part (the exhaust pipe 500 and the boss 501) of the sensor 201 including the attachment screw hole 503 is made of an aluminum alloy specified as AC2B in JIS H 5052 (thermal expansion coefficient: 23.5 × 10 ⁻⁶ / ° C.). The annular pressing portion 31 on the sensor 201 side is made of SUS310 (thermal expansion coefficient: 17.3 × 10 ⁻⁶ / ° C.), and the screwing fixing member 61 is made of SUS430 (thermal expansion coefficient: 10.4 × 10). ^-6 / ° C), there is a great difference in the thermal expansion coefficient between the three. Therefore, in the sensor mounting structure made of such a material, when they are exposed to high-temperature exhaust gas, the bosses 501 constituting the mounting screw holes 503 of the exhaust pipe 500 are relatively large (in the direction of the axis G). Swells long). Therefore, the force (compression force) that the annular pressing portion 31 of the sensor 201 presses the annular seating surface 505 of the mounting screw hole 503 is reduced, and the sealing performance is lowered. Depending on the difference in the amount of thermal expansion, the annular pressing portion 31 of the sensor 201 may float from the annular seating surface 505 of the mounting screw hole 503, and a problem such as loosening of the screwed state may occur. It should be noted that the thermal expansion in the axial direction of the mounting screw hole 503 cannot be performed in a free state at a portion where the screw is screwed, but the thermal expansion in the vicinity of the annular seating surface 505 without the screwing is possible. Is expected to expand in a state close to the free state.

  Further, in the above, when the screwing fixing member 61 is made of the same material (aluminum alloy) as the boss 501 and the annular pressing portion 31 is made of SUS310, or the annular pressing portion 31 is made of the same material (aluminum alloy) as the boss 501. Thus, even when the screwing fixing member 61 is made of SUS430, the same problem may occur depending on the temperature due to the difference in thermal expansion coefficient of each material. These problems are not only the problem of exhaust gas leaks, but also mean that the sensor 201 is not completely installed, and this causes the sensor 201 to fail due to vibration.

Under such circumstances, a boss (sensor mounting seat) 501 which is a mounting target portion for forming the mounting screw hole 503 of the sensor 201, an annular pressing portion (sealing member, rib) 31 in the sensor 201, and a screwing fixing member (nut) 61. There is a technique that prevents the screws from loosening at a high temperature by making the amount of thermal deformation of the two substantially the same (Patent Document 1). That is, the thermal expansion coefficients of the boss (sensor mounting seat) 501 forming the mounting screw hole 503 of the sensor 201, the annular pressing portion (sealing member, rib) 31 and the screwing fixing member (nut) 61 in the sensor 201. Are substantially the same, or the difference is 2 × 10 ⁻⁶ / ° C. or less.

JP 2002-122486 A

However, in the technology of Patent Document 1, the boss 501 that forms the mounting screw hole 503 of the sensor 201, the annular pressing portion 31 that forms the sensor 201, and the screwing fixing member 61 are configured to have substantially the same amount of thermal deformation. Therefore, it is necessary to form not only the sensor 201 side but also the attachment target portion of the sensor 201 such as the boss 501 in the above example with a material having substantially the same thermal expansion coefficient (for example, the same material), or The difference needs to be 2 × 10 ⁻⁶ / ° C. or less. Therefore, there is a serious drawback that the range that can be embodied as the sensor mounting structure is extremely narrow. For example, in the temperature sensor 201 made of SUS310 or 430 as described above, both the annular pressing portion 31 and the screwing fixing member 61 constituting the sensor 201 are provided with the mounting screw hole 503 of the mounting target portion (boss 501). If the thermal expansion coefficient of the boss 501 is made of a metal material larger than those of the sensor 201, such as that made of an aluminum alloy such as the above, there is no room for application of the technique of Patent Document 1. .

  In other words, aluminum alloys are widely applied to exhaust manifold system parts because they are easy to process, are lightweight and have corrosion resistance. On the other hand, the annular pressing portion 31 and the screwing fixing member 61 constituting the sensor 201 may be made of a material having a relatively small coefficient of thermal expansion, such as those made of SUS310 or 430, due to a request for heat resistance or the like. Many. In particular, the tube 11 containing the element 21 is made of stainless steel from the viewpoint of heat resistance requirements and strength. And welding is preferable in order to fix the annular pressing part 31 to this, For that purpose, it is preferable that the annular pressing part 31 is also made of stainless steel.

  The present invention has been made in view of such problems in the temperature sensor mounting structure, and the temperature sensor is used for measuring the temperature of a high-temperature gas such as the temperature of exhaust gas in an exhaust pipe or an exhaust manifold system part. The portion where the mounting screw hole for mounting the sensor is formed has a large coefficient of thermal expansion, such as an aluminum alloy, while the annular pressing portion on the sensor side or the fixing member for screwing is made of SUS, etc. To provide a temperature sensor mounting structure that can effectively prevent the occurrence of problems such as poor sealing and loosening of the screwed state as described above even at a high temperature even if the coefficient of thermal expansion is relatively small. Is the purpose.

In order to solve the above problem, the invention according to claim 1 is a temperature sensor mounting structure for measuring the temperature of a fluid in an object,
In order to attach the temperature sensor to the mounting screw hole provided in the object, an annular pressing portion provided in the temperature sensor itself is applied to the annular seating surface for holding the seal at the back of the mounting screw hole. A fixing member for screwing, which is formed in a shape and has a screw that can be screwed into the mounting screw hole on its outer peripheral surface, is externally fitted to a temperature sensor and screwed into the mounting screw hole. The temperature sensor is attached to the attachment screw hole by holding the seal in the axial direction of the screw by compressing the portion in the axial direction of the screw between the fixing member for screwing and the annular seating surface,
In the temperature sensor mounting structure in which the axial compressive stress in the annular pressing portion is reduced due to the difference in thermal expansion due to the temperature rise after the mounting,
At least one of the annular pressing portion and the screwing fixing member is formed between at least one of the annular pressing portion and the fixing member for screwing or between the annular pressing portion and the annular seating surface. A spacer made of a material having a thermal expansion coefficient larger than that of the material and having a thermal expansion coefficient equal to or greater than that of the material forming the mounting screw hole is interposed.

  The invention according to claim 2 is the temperature sensor mounting structure according to claim 1, wherein the spacer is formed of a material having a larger thermal expansion coefficient than a material forming the mounting screw hole. . According to a third aspect of the present invention, the spacer is fitted onto the temperature sensor before the screwing fixing member is screwed into the mounting screw hole, and is slidable in the axial direction of the screw of the screwing fixing member. The temperature sensor mounting structure according to claim 1, wherein the temperature sensor mounting structure is a ring-shaped or cylindrical shape. The invention according to claim 4 is the temperature sensor mounting structure according to any one of claims 1, 2, or 3, wherein the object is an exhaust pipe of an engine. .

  In the present invention, the annular pressing portion can also be applied to a configuration in which the annular pressing portion is pressed against the annular seating surface indirectly (via another member). Further, the fixing member for screwing can be applied to a structure in which the annular pressing portion is pressed indirectly (through another member) in the axial direction of the screw. That is, in the present invention, the spacer interposed between the annular pressing portion and the screwing fixing member or at least one between the annular pressing portion and the annular seating surface is directly interposed between them. It is good also as what is indirectly interposed through another members, such as a washer. Further, the spacer may be divided into a plurality of parts in the axial direction of the screw.

  In the present invention, “a temperature sensor mounting structure in which the axial compressive stress in the annular pressing portion is reduced due to a difference in thermal expansion due to a temperature increase after the mounting” refers to a temperature increase after the mounting. It means that the thermal expansion amount in the axial direction on the mounting screw hole side is larger than the thermal expansion amount (total expansion amount) in the axial direction of the annular pressing portion and the screwing fixing member due to the difference in thermal expansion. As a typical example, the part where the mounting screw hole is formed is made of the aluminum alloy having the thermal expansion coefficient as described above, and the annular pressing portion and the fixing member for screwing are made of SUS310 and 430.

As described above, for example, the material forming the part for forming the mounting screw hole in the object is made of an aluminum alloy defined as AC2B in JIS H 5052, and the thermal expansion coefficient thereof is 23.5 × 10 ^−6. / ° C., the sensor-side annular pressing part is made of SUS310, its thermal expansion coefficient is 17.3 × 10 ⁻⁶ / ° C., the screwing fixing member is made of SUS430, and its thermal expansion coefficient is In the case of the conventional sensor mounting structure in the case of 10.4 × 10 ⁻⁶ / ° C., it is as follows. That is, in this case, since the portion where the mounting screw hole is formed is larger than the thermal expansion coefficient of the material forming the annular pressing portion and the screwing fixing member, the mounting screw hole side is caused by the difference in thermal expansion due to the temperature rise after the mounting. The amount of thermal expansion in the axial direction is larger than the amount of thermal expansion (total amount of expansion) in the axial direction of the annular pressing portion and the fixing member for screwing. For this reason, the compressive stress of the axial direction which the said annular press part received has fallen rather than the raise by the temperature rise. Therefore, there is a possibility that the sealing performance is lowered and the mounting is loosened.

  On the other hand, in the present invention, even if the sensor mounting structure is made of the above material, for example, a mounting screw hole in the object is formed between the annular pressing portion and the fixing member for screwing. The mounting structure is provided with a spacer made of a material having the same or larger thermal expansion coefficient as the material forming the part. Therefore, in such a mounting structure, even when there is a temperature rise, the spacer expands in the axial direction larger than the annular pressing portion and the screwing fixing member. That is, since the expansion by the spacer can be obtained, the reduction of the compressive stress in the front-rear direction of the annular pressing portion and the screw-in fixing member can be reduced, thereby preventing the deterioration of the sealing performance and the looseness of the mounting state. Contribute. That is, in the present invention, even if there is a temperature rise after mounting, since the spacer as described above is interposed, the annular pressing portion is compared with the case where there is no spacer as in the conventional case. It is possible to obtain a remarkable effect that it is possible to reduce or prevent the deterioration of the sealing performance due to the reduction of the compressive force pushing the annular seating surface and the occurrence of looseness in the screwed state.

  As in the technique of Patent Document 1, the mounting target part (sensor mounting seat, boss) for forming the mounting screw hole, the annular pressing portion forming the sensor, and the screwing fixing member are configured to have substantially the same amount of thermal deformation. In addition to the sensor side, it is necessary to form not only the sensor side but also the part to which the sensor is attached from a material having substantially the same thermal expansion coefficient (for example, the same material). In contrast to the lack of room, the present invention has an outstanding effect in the sense that it is possible to cope with it.

  The “spacer” in the present invention has a thermal expansion coefficient larger than that of the material constituting at least one of the annular pressing portion and the screw-in fixing member, and has a thermal expansion coefficient greater than that of the material forming the mounting screw hole. What is necessary is just to select from the material. Therefore, a material having a larger thermal expansion coefficient than both of them may be selected, or when the material forming the mounting screw hole has a larger thermal expansion coefficient than the material of the annular pressing portion and the fixing member for screwing. May be the same material as the material forming the mounting screw hole. In order to prevent as much as possible the reduction of the axial compressive stress in the annular pressing portion due to the difference in thermal expansion due to the temperature rise after the mounting, it is set in consideration of the thermal expansion coefficient of the other components.

  Specifically, the tightening force generated when the screwing fixing member is screwed in is used to reduce the compression stress in the screwing direction received by the annular pressing portion and the screwing fixing member, and the mounting screw hole generated corresponding to the compression stress. The tensile stress in the same direction received by the part to be attached to be formed, the range of temperature change (rise) received by the temperature sensor, the material (longitudinal elastic modulus, thermal expansion coefficient, etc.) of the material forming these parts and parts, In view of the temperature change (thermal cycle) from the time of mounting the temperature sensor to the mounting screw hole in relation to the length and cross-sectional area in the front-rear direction, the deterioration of the seal and the looseness of the mounting state occur. What is necessary is just to design so that it may prevent. Of course, depending on the portion of the mounting screw hole, the material forming the annular pressing portion and the fixing member for screwing, and the material forming the spacer, the annular pressing may be caused by a difference in thermal expansion due to a temperature rise after the mounting. It is also possible to increase the axial compressive stress in the part.

The longitudinal cross-sectional view of the sensor used for 1st Embodiment which actualized the attachment structure of the temperature sensor of this invention, and its principal part enlarged view. The longitudinal cross-sectional view for description of the process of obtaining the attachment structure of the example of 1st Embodiment. The longitudinal cross-sectional view for description of the process of obtaining the attachment structure of the example of 1st Embodiment. The longitudinal cross-sectional view of the attachment structure of the example of 1st Embodiment. The A section enlarged view of FIG. The longitudinal cross-sectional view of 2nd Embodiment which actualized the attachment structure of the temperature sensor of this invention. The B section enlarged view of FIG. The principal part enlarged view of 3rd Embodiment which actualized the attachment structure of the temperature sensor of this invention. The longitudinal section of the attachment structure of the conventional temperature sensor.

  An embodiment (first embodiment) of a temperature sensor mounting structure embodying the present invention will be described in detail with reference to FIGS. However, in this example, the temperature sensor 101 for measuring the temperature of the exhaust gas of the engine will be described in a case where it is attached to the attachment screw hole 503 provided in the attachment target portion (boss) 501 of the exhaust pipe (or exhaust manifold) 500. In the figure, reference numeral 101 denotes a sensor made of SUS310 having a circular cross section 11 whose tip (lower end in the figure) is closed, and a temperature sensor element disposed at the tip or a portion near the tip in the tube 11. 21 as a main component. Among these elements, the element 21 is disposed on the distal end side of the sheath tube 25 inserted and disposed in the tube 11. The sheath tube 25 is filled with insulating powder in a state where the two core wires 24 are inserted, and two wires extending from the rear of the element 21 are provided at the tip of the core wire 24 protruding from the tip of the sheath tube 25. Electrode wire 23 is connected. Note that a portion closer to the distal end of the tube 11 is slightly reduced in diameter so as to receive the distal end of the sheath tube 25 therein, and has a smaller diameter than a portion in which the sheath tube 25 is inserted. The tube 11 is filled with cement in order to suppress the swing of the element 21.

The outer periphery of the portion near the rear end of the tube 11 is outwardly pressed so as to be pressed against the annular seating surface 505 for holding the seal at the back of the mounting screw hole 503 of the boss 501 forming the sensor mounting target portion of the exhaust pipe 500. A projecting flange-shaped annular pressing portion 31 is press-fitted and further fixed by welding. The mounting annular pressing portion 31 is made of SUS310 (coefficient of thermal expansion: 17.3 × 10 ⁻⁶ / ° C.) and is circular when viewed from the direction of the axis G of the tube 11 forming the sensor 101 (viewed from the front end side). It is formed so as to form an annular shape, and includes a cylindrical portion 33 extending rearward along the inner peripheral surface thereof. The annular pressing portion 31 is fixed to the outer peripheral surface near the rear end of the tube 11 via the inner peripheral surface of the cylindrical portion 33 by press-fitting and further welding. The annular pressing portion 31 has a circular annular rear end-facing surface 35 perpendicular to the central axis (axis line) G of the tube 11 on the rear side, but the tip end surface 36 is located near the outer periphery. 2 and 3, a tapered surface portion 36a formed in a tapered shape so as to be pressed against a sharply tapered annular seating surface 505 at the back of the mounting screw hole 503 is formed. The portion near the central axis forms an annular plane 36b perpendicular to the axis G. The outer peripheral surface 37 of the annular pressing portion 31 has a cylindrical surface whose outer diameter is smaller than the inner diameter of the screw of the mounting screw hole 503.

  On the other hand, on the outer peripheral surface of the tubular portion 33 extending rearward in the annular pressing portion 31, a large diameter tube (protective tube) concentric with the tube 11 and the sheath tube 25 and having a larger diameter than that of the tube 11 and the sheath tube 25 and extending rearward. 41 is fixed. The large-diameter tube 41 is fitted on the outer peripheral surface of the cylindrical portion 33 of the annular pressing portion 31 at a portion closer to the distal end, and its distal end is brought into contact with the rear end facing surface 35 of the annular pressing portion 31. Is fixed to the outer peripheral surface of the cylindrical portion 33 by welding or the like. On the other hand, the rear end of the sheath tube 25 is located at the front and rear intermediate portion in the large-diameter tube 41, and the core wire 24 drawn from the rear end and each electric wire (lead wire) 28 for taking out an electric signal Are connected via caulking terminals 27, and the electric wires 28 are drawn to the outside at the rear end of the large-diameter tube 41. An elastic sealing material 47 is disposed in the rear end portion 45 of the large-diameter tube 41, and each electric wire 28 is passed through the sealing material 47. Then, the rear end portion 45 of the large-diameter tube 41 is squeezed into a reduced diameter so that the internal seal is held and each electric wire 28 is fixed at the rear end.

Now, on the rear side (rear side) of the annular pressing portion 31 on the rear end side 35, an annular or cylindrical spacer 51 forming the main part of the present invention is concentrically outside the large-diameter tube 41. In this example, they are loosely fitted. The spacer 51 has a cylindrical shape (or an annular shape) in which one end (surface) 53 on the front end side contacts the rear end-facing surface 35 of the annular pressing portion 31. In this example, the inner diameter of the large-diameter tube 41 is It is formed so as to be larger than the outer diameter, and is arranged so as to be in direct contact with the rear end-facing surface 35 of the annular pressing portion 31 so as to be slidable in the axis G direction with respect to the large-diameter tube 41 (with a gap fitted). The spacer 51 only needs to have one end (surface) 53 on the front end side in contact with the rear end facing surface 35 of the annular pressing portion 31 outside the large diameter tube 41. Although it may be fixed to the outer peripheral surface of the large-diameter tube 41 by press fitting or the like, in this example, the large-diameter tube 41 is disposed so as to be removable from the rear. The spacer 51 has a cylindrical outer peripheral surface 55 and an outer diameter smaller than the inner diameter of the screw of the mounting screw hole 503. For example, the spacer 51 is made of an aluminum alloy (thermal expansion) defined as A5056 in JIS H 4040. Coefficient: 24.3 × 10 ⁻⁶ / ° C.).

A screw fixing member 61 made of SUS430 (thermal expansion coefficient: 10.4 × 10 ⁻⁶ / ° C.) is idled on the rear end (surface) 57 side of the spacer 51 and outside the large diameter tube 41. It is fitted externally. This screwing fixing member 61 has a cylindrical part (cylindrical part) 60 whose inner diameter is larger than the outer diameter of the large-diameter tube 41, and an attachment formed in the exhaust pipe 500 on the outer peripheral surface of the cylindrical part 60. A screw 62 that can be screwed into the screw hole 503 is provided over substantially the entire length. Such a screwing fixing member 61 is arranged so as to be removable from the rear side of the large-diameter tube 41, but in this example, the screwing fixing member 61 has its tip 63 directly contacting the rear end 57 of the spacer 51. Are arranged as follows. A screw-in polygon part 67 is formed on the outer periphery of the rear end of the screw-in fixing member 61.

Thus, the temperature sensor 101 having the above-described configuration is mounted in the mounting screw hole 503 formed in the exhaust pipe 500 as follows. That is, as shown in FIG. 2, the sensor 101 in which the screwing fixing member 61 is slid rearward is inserted into the mounting screw hole 503 from the tip side. In FIG. 2, the spacer 51 is illustrated away from the rear end facing surface 35 of the annular pressing portion 31. Then, as shown in FIG. 3, the annular pressing portion 31 provided in the temperature sensor 101 is applied to the annular seating surface 505 for holding the back seal, and the rearward facing surface 35 of the annular pressing portion 31 is applied. Then, the spacer 51 is brought into contact. 4 and 5, the fixing member 61 for screwing behind the spacer 51 is screwed into the mounting screw hole 503 with a predetermined tightening torque. By this screwing, the annular pressing portion 31 is compressed in the axis G direction of the screw 62 between the fixing member 61 for screwing and the annular seating surface 505 via the spacer 51. In this way, the temperature sensor 101 presses the annular pressing portion 31 against the annular seating surface 505 for holding the seal at the back of the attachment screw hole 503, and is attached to the attachment screw hole 503 while holding the seal there. In the present embodiment, the boss 501 having the mounting screw hole 503 is made of an aluminum alloy (thermal expansion coefficient: 23.5 × 10 ⁻⁶ / ° C.) defined as AC2B in JIS H 5052. Yes.

  In this attached state, the annular pressing portion 31 on the sensor 101 side, the spacer 51, and further the fixing member 61 for screwing are compressed in the direction of the axis G of the screw 62. Subjected to compressive stress in the direction. On the other hand, the mounting screw hole 503 is pulled from the annular seating surface 505 in the front-rear direction (screw axis G direction) toward the inlet side (upper side in FIG. 4) of the screw hole 503, and Has a tensile stress in the direction of its axis G. That is, in such a mounting structure of the sensor 101, the annular pressing portion 31 on the sensor 101 side, the spacer 51, and the screwing fixing member 61 are subjected to compressive strain in the direction of the axis G of the screw 62. Corresponding to the above, the mounting screw hole 503 has a tensile strain in the same direction. However, in the boss 501 including the screw fixing member 61 and the screw hole 503, it is considered that the screwed portion is distorted only by the play of the screw. The temperature sensor 101 is attached in such a manner as to press the tip-facing surface 36 of the annular pressing portion 31 against the annular seating surface 505 in the attachment screw hole 503, ensuring a seal therebetween.

  In such a mounting structure of the sensor 101, if there is a temperature rise of about 200 ° C. to 500 ° C., for example, then the mounting structure portion will thermally expand. At this time, the coaxial G of the mounting screw hole 503 is determined by the sum of the thermal expansion amounts in the axis G direction of the annular pressing portion 31 and the screwing fixing member 61 due to the difference in the thermal expansion coefficient of the material constituting each portion (or each member). The amount of thermal expansion in the direction is larger. Therefore, the compressive stress in the direction of the axis G that the annular pressing portion 31 and the screwing fixing member 61 received inside before the temperature rise decreases due to the temperature rise. However, in this example, an aluminum alloy spacer 51 having a larger thermal expansion coefficient than the stainless steel constituting them is interposed between the annular pressing portion 31 and the screwing fixing member 61. For this reason, the total amount of thermal expansion in the direction of the axis G of the annular pressing portion 31, the spacer 51, and the screwing fixing member 61 is larger than the total amount of thermal expansion in the case where there is no such spacer 51 as in the prior art. As a whole, it can expand greatly in the front-rear direction. Therefore, according to the mounting structure of the sensor 101 of this example, even if the temperature rises after the mounting of the sensor 101, the spacer 51 as described above is interposed, so that it is provided as much as it is provided. Compared to a conventional mounting structure that is not provided, since the decrease in compressive force that the annular pressing portion 31 has pressed the annular seating surface 505 can be reduced, the decrease in sealing performance and the occurrence of looseness in the screwed state can be reduced.

  That is, in the case of the mounting structure of the sensor 101 of this example, the annular pressing portion 31 and the screw-in fixing, which are constituent members on the sensor 101 side, compared to the mounting target portion (boss 501) where the mounting screw hole 503 is formed. Although the member 61 has a small coefficient of thermal expansion, the spacer 51, which is a separate member, has a coefficient of thermal expansion greater than that of the material forming the annular pressing portion 31 and the screwing fixing member 61, and is larger than that of the boss 501. Since a material having a coefficient is used, the decrease in compressive force that the annular pressing portion 31 is pressing the annular seating surface 505 can be reduced. Therefore, there is an effect that the present invention can be widely applied to a wide variety of mounting structures of the temperature sensor 101 regardless of the difference in the material forming the mounting target portion or the like that forms the mounting screw hole 503.

  The spacer 51 has a temperature rise range that is received by the mounting structure portion of the temperature sensor 101, and even in that case, the spacer 51 can be thermally expanded so as to ensure the necessary compressive stress for the annular pressing portion 31, that is, the temperature rise. Various conditions such as its own length in the direction of the axis G may be designed so that the compressive stress necessary for securing the seal is held in the annular pressing portion 31 at times. The spacer 51 of the present embodiment has a length (that is, thickness) in the direction of the axis G of 4.0 mm.

  In the above example, since the spacer 51 is cylindrical or annular, the temperature sensor 101 is not easily separated or detached from the large diameter tube 41. However, the spacer 51 is not necessarily required to be cylindrical or annular. In the above example, the spacer 51 is made of one cylindrical or annular member (component). However, the spacer 51 may be divided into a plurality of parts in the axis G direction. In this way, if the amount of thermal expansion required on the sensor 101 side differs depending on the mounting structure, for example, the thermal expansion of the mounting screw hole on the counterpart side where the sensor is mounted, it is divided. It is convenient because it can cope with thermal expansion by using an appropriate number of spacers (divided bodies). Further, in the above example, the spacer 51 is embodied as a structure directly sandwiched between the annular pressing portion 31 and the screwing fixing member 61. However, for example, a slip washer may be interposed therebetween. Further, a gasket for holding a seal may be interposed between the annular seating surface 505 of the mounting screw hole 503 and the annular pressing portion 31 on the sensor 101 side.

  Next, a second embodiment in which the sensor 101 mounting structure of the present invention is embodied will be described with reference to FIG. However, in this example, in addition to the spacer 51 in the above embodiment (hereinafter also referred to as the first spacer 51), there is another difference between the annular seating surface 505 of the mounting screw hole 503 and the annular pressing portion 31 on the sensor 101 side. The only difference is that the spacer (hereinafter also referred to as a second spacer) 71 is disposed, and there is no substantial difference from the above-described embodiment. Therefore, only this difference will be described, and the same parts will be denoted by the same reference numerals.

  That is, the second spacer 71 used in this embodiment, like the first spacer 51, has a larger coefficient of thermal expansion than the material forming the annular pressing portion 31 and the screwing fixing member 61, and the boss 501. It is made of a material having the same thermal expansion coefficient, specifically, made of an aluminum alloy defined as A5056 in JIS H 4040, has an annular shape, and the tip 73 has the same shape as the tip-facing surface 36 of the annular pressing portion 31, The outer peripheral surface 75 is formed with the same outer diameter. The rear end 77 is formed in a concave shape that is in close contact with the tip-facing surface 36 of the annular pressing portion 31, the inner diameter is the same as or larger than the outer diameter of the tube 11, and the mounting screw hole 503 Before the sensor 101 is inserted into the tube 11, it is externally fitted (press-fit or loosely fitted) to the tube 11, or before the sensor 101 is inserted into the mounting screw hole 503, the inner annular seating surface 505 is preliminarily inserted. Placed in. Thus, in the same manner as described above, the sensor 101 is inserted into the mounting screw hole 503, and the tip-facing surface 36 of the annular pressing portion 31 is pressed against the annular seating surface 505 via the second spacer 71. Next, in the same manner as described above, the first spacer 51 is disposed and interposed on the rear-end-facing surface 35 of the annular pressing portion 31, and the fixing member 61 for screwing is screwed into the mounting screw hole 503 from the rear under this state. That is why it is installed.

  Therefore, in this example, in addition to the first spacer 51 disposed between the annular pressing portion 31 and the screwing fixing member 61 by the screwing, and between the annular pressing portion 31 and the annular seating surface 505. Both the arranged second spacers 71 are attached by being compressed in the direction of the axis G of the screw 62. In this example, the amount of thermal expansion in the front-rear direction at a high temperature is increased corresponding to the front-rear length and the cross-sectional area of the second spacer 71 by providing the second spacer 71 in addition to the first spacer 51. Since it can be ensured, it is more effective than the above embodiment in preventing the deterioration of sealing performance and the occurrence of screw loosening.

  As is clear from this example, only the second spacer 71 may be interposed between the annular pressing portion 31 and the annular seating surface 505 without providing the first spacer 51 in this example. FIG. 8 shows an example of this, but the only difference from the one shown in FIGS. 6 and 7 is that the first spacer 51 is not provided. A description thereof will be omitted. In addition, since such a 2nd spacer 71 also bears a seal | sticker holding function, it is preferable to select from the raw material which has an elastic coefficient which does not plastically deform in the state which attached the sensor 101 to the attachment screw hole 503. . Also, in the case where the second spacer 71 as shown in FIGS. 6 to 8 is provided, it may be divided into a plurality of pieces, for example, before and after that, as described above. Further, the second spacer 71 may also have a washer or the like so as to indirectly contact the annular pressing portion 31 or the annular seating surface 505.

The temperature sensor 101 of the present invention is not limited to the above-described examples, and can be embodied with appropriate modifications within a range not departing from the gist thereof. For example, in the above example, the spacers 51 and 71 are made of an aluminum alloy defined as A5056 in JIS H 4040. However, the material for forming the mounting screw hole on the object side, the annular pressing portion on the sensor side, or for screwing In consideration of the material forming the fixing member, it may be formed of an appropriate material. That is, it is only necessary to reduce the reduction of the compressive stress in the axis G direction of the screw of the annular pressing portion due to the difference in thermal expansion due to the temperature rise after the sensor is attached. For example, when the boss 501 having the mounting screw hole 503 is made of an aluminum alloy (thermal expansion coefficient: 23.5 × 10 ⁻⁶ / ° C.) defined as AC2B in JIS H 5052, the same material (heat The spacers 51 and 71 may be configured using an aluminum alloy having an expansion coefficient), zinc (thermal expansion coefficient: 26.3 × 10 ⁻⁶ / ° C.), magnesium (25.4 × 10 ^−6). / ° C), or an alloy thereof, a spacer made of a material having a thermal expansion coefficient equal to or higher than that of the boss 501 may be applied.

  In addition, the spacer is made of a material having a larger thermal expansion coefficient than either the annular pressing portion 31 or the screwing fixing member 61, and the mounting screw hole 503 takes into account the amount of thermal expansion that occurs in the direction of the axis G. In order to reduce the decrease in the compressive stress in the direction of the axis G of the annular pressing portion 31 due to the difference in thermal expansion due to the subsequent temperature rise, the temperature sensor is adjusted based on the compressive strain at the time of installation, the dimensions of the spacer itself, and the like It may be set accordingly. In the above example, the sensor is mounted on the exhaust pipe (manifold) of the engine and measures the temperature of the exhaust gas. However, the present invention is a sensor for measuring the temperature of other fluids (gas, liquid). It can also be applied to the mounting structure.

36 Temperature sensor annular pressing portions 51, 71 Spacer 61 Screw-in fixing member 62 Screw-in fixing member screw 101 Temperature sensor 500 Exhaust pipe (object)
503 Mounting screw hole 505 Annular seating surface G for holding the seal at the back of the mounting screw hole Screw shaft

Claims (4)

A temperature sensor mounting structure for measuring the temperature of a fluid in an object,
In order to attach the temperature sensor to the mounting screw hole provided in the object, an annular pressing portion provided in the temperature sensor itself is applied to the annular seating surface for holding the seal at the back of the mounting screw hole. A fixing member for screwing, which is formed in a shape and has a screw that can be screwed into the mounting screw hole on its outer peripheral surface, is externally fitted to a temperature sensor and screwed into the mounting screw hole. The temperature sensor is attached to the attachment screw hole by holding the seal in the axial direction of the screw by compressing the portion in the axial direction of the screw between the fixing member for screwing and the annular seating surface,
In the temperature sensor mounting structure in which the axial compressive stress in the annular pressing portion is reduced due to the difference in thermal expansion due to the temperature rise after the mounting,
At least one of the annular pressing portion and the screwing fixing member is formed between at least one of the annular pressing portion and the fixing member for screwing or between the annular pressing portion and the annular seating surface. A temperature sensor mounting structure comprising a spacer made of a material having a thermal expansion coefficient larger than that of the material and having a thermal expansion coefficient equal to or greater than that of the material forming the mounting screw hole.   2. The temperature sensor mounting structure according to claim 1, wherein the spacer is formed of a material having a larger coefficient of thermal expansion than a material for forming the mounting screw hole.   The spacer is an annular or cylindrical shape that is externally fitted to the temperature sensor and is slidable in the axial direction of the screw of the fixing member for screwing before the fixing member for screwing is screwed into the mounting screw hole. The temperature sensor mounting structure according to any one of claims 1 and 2.   4. The temperature sensor mounting structure according to claim 1, wherein the object is an exhaust pipe of an engine. 5.

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