JP6499522B2 - Temperature sensor - Google Patents

Description

  The present invention relates to a temperature sensor, and more particularly to a temperature sensor suitable for detecting the temperature of exhaust gas discharged from an internal combustion engine such as an automobile.

  2. Description of the Related Art Conventionally, a temperature sensor that detects a temperature of exhaust gas discharged from an internal combustion engine such as an automobile by a temperature sensing element (for example, a thermistor element or a platinum side temperature resistor) is known. As such a temperature sensor, there is one described in JP 2012-42451 A (Patent Document 1). The temperature sensor of Patent Document 1 includes a metal tube (for example, made of SUS) whose tip is closed, and a temperature sensor element arranged in a state where the tip is pressed against the tip in the tube. Behind the temperature sensor element in the tube are an electrode wire extending rearward from the element, an element support that is an insulating member passing through the electrode wire, and an insulator tube that is an insulator for wiring passing through a core wire connected to the electrode wire (Insulating tube) is arranged. A lead wire is connected to the core wire protruding rearward from the rear end of the insulator tube through a terminal fitting, and a portion near the front end of the lead wire including this connecting portion and the insulating resin layer are connected to the rear end portion of the tube. Is passed through the sealing member. The seal member is made of rubber, and is deformed and fixed in the portion by crimping the portion near the rear end of the tube in a reduced diameter.

JP 2012-42451 (paragraph 0033 and FIG. 1)

  Generally, rubber or resin is used for the seal member of the temperature sensor. In addition, a heat shrinkable tube is provided at a connection portion between the sheath wire (core wire) and the lead wire in order to protect the connection portion. Since these members have a low heat-resistant temperature, they must be placed in a relatively low temperature place of 200 ° C. or lower.

  The temperature sensing part (temperature sensor element) of the temperature sensor is exposed to high temperatures due to the heat of the exhaust gas, but in order to reduce the temperature at the rear end (lead wire side end) of the metal tube and the lead wire connection, The heat received from the exhaust pipe is extended to the outside of the metal tube by extending the length of the tube. For this reason, a metal tube becomes long and the length (dimension) of the extending direction (longitudinal direction) of the core wire in the temperature sensor becomes long. For this reason, when the temperature sensor is mounted on the vehicle, it is easily affected by the layout of the peripheral components, and the improvement in mountability is limited.

  An object of the present invention is to provide a temperature sensor that can be reduced in length in the longitudinal direction and has improved mountability to a vehicle.

In order to achieve the above object, the temperature sensor of the present invention is a cylindrical metal tube, a temperature sensing element disposed inside one end of the metal tube, and electrically connected to the temperature sensing element, In the temperature sensor comprising a lead wire drawn from the other end of the metal tube,
A disc-shaped metal sealing member having a through hole is fixed to the other end portion of the metal tube, the lead wire is drawn out from the through hole, and a gap between the lead wire and the through hole is glass. Hermetically sealed using materials ,
The lead-out electric wire is connected to the resin-coated electric wire outside the metal tube, the connecting portion between the core wire and the resin-coated electric wire is covered with a heat-shrinkable tube, and the outside between the metal seal member and the heat-shrinkable tube is covered. The surface is ceramic sprayed .

  According to this invention, since the length of the temperature sensor in the longitudinal direction can be shortened, the temperature sensor can be mounted even in a narrow space.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a section lineblock diagram showing the whole temperature sensor 1A concerning the 1st example of the present invention. It is sectional drawing which expands and shows the connection part of the heat-resistant electric wire 7 and the sheath wire 6 in a 1st Example. FIG. 3 is a configuration diagram of a connection portion showing a connection method between a heat-resistant electric wire 7 and a sheath wire 6 using a terminal 17. It is a section lineblock diagram showing the whole temperature sensor 1B concerning the 2nd example of the present invention. It is sectional drawing which expands and shows the connection part of the resin-coated electric wire 18 and the sheath wire 6 in a 2nd Example.

  Embodiments according to the present invention will be described below with reference to the drawings. In the embodiments described below, common components are denoted by the same reference numerals and description thereof is omitted.

  FIG. 1 is a cross-sectional configuration diagram showing an entire temperature sensor 1A according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a connection portion between the heat-resistant electric wire 7 and the sheath wire 6 in the first embodiment.

  A temperature sensing element (temperature sensor element) 2 for detecting temperature is composed of a platinum resistance temperature detector or a thermistor. A temperature signal from the temperature sensing element 2 is sent to the sheath wire (core wire) 6 through the electrode wire 13. The sheath wire 6 and the electrode wire 13 are made of a high melting point metal such as Inconel or platinum. The sheath tube 4 includes a sheath holding member 5 and a sheath wire 6 on the inner side, the temperature sensing element 2 is connected to one end of the sheath wire 6, and a heat-resistant electric wire (heat-resistant lead wire) 7 is connected to the other end. Is done.

  A cap 3 that protects the temperature sensing element 2 is fixed to the sheath tube 4 by welding, and the cap 3 is filled with a filler 14 made of magnesia or alumina. Since the cap 3 and the sheath tube 4 are disposed inside the exhaust pipe of the internal combustion engine, a high melting point metal such as Inconel or SUS is preferable.

  The sheath holding material 5 is made of a powder mainly composed of magnesia or alumina, and holds the sheath wire 6 in a state of being separated from the inner peripheral surface of the sheath tube 4. The sheath holding member 5 functions as an electrical insulating member. The in-vehicle temperature sensor 1A receives strong vibration, but the sheath wire 6 is stably held inside the sheath tube 4 or the cap 3 by the sheath holding material 5 and the temperature sensitive element 2 by the filler 14. .

  The heat-resistant electric wire 7 includes a conductive wire 15 and an insulating coating 16, and the insulating coating 16 is made of glass braid having high temperature and heat resistance. The conducting wire 15 is a metal. The heat-resistant electric wire 7 desirably has heat resistance of, for example, 300 ° C. or higher. A cylindrical mounting base (terminal base) 8 is fixed to the end of the sheath tube 4 on the side to which the heat-resistant electric wire 7 is connected by welding. The mounting base 8 is a metal member and can be configured using, for example, SUS.

  A connecting portion 21 between the sheath wire 6 and the heat-resistant electric wire 7 is disposed inside the mounting base 8 and filled with the electric wire holding material 10. The electric wire holding material 10 is made of a powder or paste-like material whose main component is ceramic. The wire holding material 10 is an electrically insulating material. The heat-resistant electric wire 7 is disposed so that the end of the insulating coating 16 is located inside the mounting base 8 and the conductive wire 15 is exposed from the insulating coating 16 inside the mounting base 8.

  The end of the mounting base 8 on the insertion side of the heat-resistant electric wire 7 is provided with a disk-shaped metal seal member 12 provided with two through holes 11. The metal sealing member 12 is fixed to the mounting base 8 by welding after passing the heat-resistant electric wire 7 through the through hole 11. The gap around the heat-resistant electric wire 7 in the through hole 11 is hermetically sealed by the glass material 22. The hermetic seal 23 seals the glass material 22 in the through hole 11 by applying compressive stress between the metal mounting base 8 and the metal conductor 15 of the heat-resistant electric wire 7. The hermetic seal 23 is excellent in heat resistance and electrical insulation, and seals the inside of the mounting base 8 in an airtight state.

  A mounting member 9 is fixed to the mounting base 8. Since the attachment member 9 is attached to the exhaust pipe of the internal combustion engine, the attachment base 8 is also relatively hot. However, in this embodiment, since the lead-out portion of the heat-resistant electric wire 7 of the mounting base 8 is sealed with a hermetic seal using metal and glass, the seal portion can be arranged in a state close to the exhaust pipe of the internal combustion engine. it can.

  The heat-resistant electric wire 7 is composed of a metal conductive wire 15 and a glass braided insulating coating 16 and has a good compatibility with a hermetic seal. The temperature sensor 1A of the present embodiment can ensure the airtightness inside the mounting member 8 even in a high temperature environment due to the above structure, and the inside of the temperature sensor 1A is not contaminated by impurities. By arranging the seal portion in a high temperature environment, the longitudinal length of the temperature sensor 1A can be shortened, so that the temperature sensor 1A can be mounted even in a narrow space. Therefore, the mountability of the temperature sensor 1A to the internal combustion engine can be improved.

  The sheath wire 5 and the heat-resistant electric wire 7 may be connected using a terminal 17 as shown in FIG. The terminal 17 and the sheath wire 6 are fixed by welding, and the terminal 17 and the heat-resistant electric wire 7 are fixed by caulking. The sheath wire 6 is made of the same material as the terminal 17. By using the terminal 17, even when the materials of the sheath wire 5 and the heat-resistant electric wire 7 are different from each other, they can be reliably connected, and the assembly workability is improved.

  FIG. 4 is a cross-sectional configuration diagram showing the entire temperature sensor 1B according to the second embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view showing a connecting portion between the resin-coated electric wire 18 and the sheath wire 6 in the second embodiment.

  The sheath wire (core wire) 6 is passed through the two through holes 11 of the metal seal member 12. That is, in the present embodiment, the sheath wire 6 is drawn from the inside of the mounting base 8 to the outside. The metal sealing member 12 is fixed to the mounting base 8 as in the first embodiment. The gap around the sheath wire 6 in the through hole 11 is hermetically sealed with a glass material. As described in the first embodiment, the sheath wire 6 is made of a high melting point metal such as Inconel or platinum. Also in the present embodiment, a compressive stress is applied to the glass material 22 between the metal sealing member 12 and the metal sheath wire 6.

  With the above structure, the inside of the mounting member 8 can be hermetically sealed even under a high temperature environment. The lead wire side end portion 6 a of the sheath wire 6 is connected to a resin-coated electric wire (resin-coated lead wire) 18, and the connection portion is protected by a heat shrinkable tube 19. Since the heat-shrinkable tube 19 and the attachment member 8 are not in contact with each other and are spatially separated, the heat-shrinkable tube 19 and the resin-coated electric wire 18 can be disposed in a relatively low temperature environment.

  A ceramic material 20 is sprayed on the outer surface of the sheath wire 6 at least between the metal seal member 12 and the heat shrinkable tube 19. In this embodiment, the ceramic material 20 covers the outer end face of the metal sealing member 12 and the outer surface of the sheath wire 6. A part of the ceramic material 20 that covers the outer surface of the sheath wire 6 is covered with a heat shrinkable tube 19.

  Although the space between the metal seal member 12 and the heat shrinkable tube 19 is exposed to the outside air, since the sheath wire 6 is insulated by the ceramic material 20, there is no short circuit between terminals due to moisture or the like. Moreover, the coating | coated part by the ceramic material 20 has flexibility, and has contributed to the mountability improvement of the temperature sensor 1B.

  As described above, in the first and second embodiments, the cylindrical metal tubes 3, 4, 8 are hermetically sealed with the cap 3, the sheath tube 4, and the mounting base 8. The temperature sensitive element 2 is arranged inside one end (end side end) of the metal tubes 3, 4, 8. A disc-shaped metal seal member 12 having two through holes 11 is fixed to the other end portions of the metal tubes 3, 4, and 8. The lead wires 6 and 7 are pulled out from the through hole 11, and the gap between the lead wires 6 and 7 and the through hole 11 is hermetically sealed using a glass material. In the first embodiment, the lead wire is constituted by the heat resistant wire 7. In the second embodiment, the lead wire is constituted by a sheath wire (core wire) 6.

  In addition, this invention is not limited to each above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1A, 1B ... Temperature sensor, 2 ... Temperature sensing element (temperature sensor element), 3 ... Cap, 4 ... Sheath tube, 5 ... Sheath holding material, 6 ... Sheath wire (core wire), 7 ... Heat-resistant electric wire (heat-resistant lead wire) 8 ... Mounting base, 9 ... Mounting member, 10 ... Electric wire holding material, 11 ... Through hole, 12 ... Metal seal member, 13 ... Electrode wire, 14 ... Filler, 15 ... Conductor, 16 ... Insulation coating, 17 ... Terminal: 18 ... Resin-coated electric wire (resin-coated lead wire), 19 ... Heat shrinkable tube, 20 ... Ceramic material, 21 ... Connection between sheath wire 6 and heat-resistant electric wire 7, 22 ... Glass material, 23 ... Hermetic seal.

Claims (2)

A cylindrical metal tube, a temperature sensing element disposed inside one end portion of the metal tube, and a lead wire electrically connected to the temperature sensing element and drawn from the other end portion of the metal tube. In the temperature sensor
A disc-shaped metal sealing member having a through hole is fixed to the other end portion of the metal tube, the lead wire is drawn out from the through hole, and a gap between the lead wire and the through hole is glass. Hermetically sealed using materials,
The lead-out electric wire is connected to the resin-coated electric wire outside the metal tube, the connecting portion between the core wire and the resin-coated electric wire is covered with a heat-shrinkable tube, and the outside between the metal seal member and the heat-shrinkable tube is covered. A temperature sensor characterized in that the surface is ceramic sprayed. The temperature sensor according to claim 1,
Wherein the metal tube comprises a metal cap which is provided at one end of the sheath tube metal tube,
The temperature sensor according to claim 1, wherein the lead wire is formed of a metal core wire that is inserted through the sheath tube.

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