JP2019060782A - Temperature sensor - Google Patents

Abstract

To provide a temperature sensor with which it is possible to improve responsiveness efficiently.SOLUTION: A temperature sensor 1 comprises a metal tube 2, a thermosensor 3, a pair of lead wires 31, an insulating support 4 and a heat insulator 5. The tip of the metal tube 2 is opened as a tip opening 20. The thermosensor 3 is disposed in the tip opening 20 and used to measure the temperature of a measurement object. The pair of lead wires 31 are connected to the thermosensor 3. The insulating support 4 is disposed inside the metal tube 2 and composed of a ceramic material for insulating the metal tube 2 and the lead wires 31, the insulating support 4 being used to support the lead wires 31 on the metal tube 2. The heat insulator 5 is disposed around the thermosensor 3 in the tip opening 20 in a state of covering a tip end face 401 of the insulating support 4, and is composed of a ceramic material whose thermal conductivity is lower than the ceramic material that constitutes the insulating support 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a temperature sensor using a temperature sensitive element for measuring temperature.

  A temperature sensor, for example, is arranged in the exhaust pipe of a motor vehicle and is used to measure the temperature of the exhaust gas flowing through the exhaust pipe. For example, in the temperature sensor of Patent Document 1, in order to secure strength against vibration, it is described that the insulating pipe and the thermistor disposed at the tip of the insulating pipe are fixed by heat resistant cement as an insulating material. ing. Further, the thermistor, the insulating pipe and the heat resistant cement are fixed in the metal pipe using another heat resistant cement.

Japanese Patent Application Laid-Open No. 62-278421

  The temperature sensor is required to be responsive to rapidly detect changes in the temperature of the atmosphere gas such as exhaust gas. In order to improve this response, it is conceivable to improve the heat transfer to a temperature sensing element such as a thermistor. However, in the conventional temperature sensor, the temperature sensing element is in contact with the tip of the metal pipe via the insulating material, and heat transfer is likely to occur between the temperature sensor and the metal pipe.

  When measuring the temperature of the atmosphere gas by the temperature sensor, if the temperature of the atmosphere gas becomes higher than the temperature of the temperature sensing element, the heat received by the temperature sensing element is conducted to the metal pipe (deprived) . As a result, the temperature of the temperature sensitive element does not easily rise, and it takes time for the temperature of the temperature sensitive element to reach the temperature of the atmosphere gas, which impairs the responsiveness of the temperature sensor.

  In addition, when the temperature of the atmosphere gas is lower than the temperature of the temperature sensing element when the temperature of the atmosphere gas is measured by the temperature sensor, the heat remaining in the metal tube is conducted to the temperature sensing element. As a result, the temperature of the temperature sensitive element does not easily decrease, and it takes time for the temperature of the temperature sensitive element to reach the temperature of the atmosphere gas, which impairs the responsiveness of the temperature sensor.

  Therefore, in order to improve the response of the temperature sensor, it was found effective to devise a device in which the heat transfer between the temperature sensitive element and the metal tube is suppressed.

  The present invention has been made in view of such problems, and has been obtained to provide a temperature sensor capable of effectively improving response.

One embodiment of the present invention is a metal tube (2) whose tip is opened as a tip opening (20);
A temperature sensitive element (3) disposed at the tip end opening for measuring a temperature;
A pair of lead wires (31) connected to the temperature sensitive element;
An insulating support (4, 4A, 4B), which is disposed in the metal tube and made of a ceramic material which insulates the metal tube from the lead wire, and for supporting the lead wire on the metal tube;
A ceramic material having a thermal conductivity lower than that of the ceramic material constituting the insulating support material, disposed in the state of covering the distal end surface (401) of the insulating support material around the temperature sensing element in the distal end opening And a thermal insulator (5), and the temperature sensor (1).

  In the temperature sensor according to the one aspect, the tip of the metal tube is opened as a tip opening, and the temperature sensing element is disposed in the tip opening. That is, the curved tip portion (bottom portion) is not formed at the tip position of the metal pipe. Therefore, the temperature sensitive element can be kept away from the metal tube while being disposed at the tip position of the temperature sensor. Thereby, the heat conduction from a temperature sensing element to a metal pipe and the heat conduction from a metal pipe to a temperature sensing element can be controlled.

  In addition, when the metal tube does not exist on the tip side of the temperature sensing element, the temperature sensing element receives heat by heat radiation, heat transfer (heat convection), etc. from the atmosphere gas as the measurement target. The element can be made susceptible to heat. In addition, when the heat of the temperature sensing element is released to the atmosphere gas or the like by the absence of the metal tube on the tip side of the temperature sensing element, the heat remaining in the metal tube is less likely to be transmitted to the temperature sensing element. Can.

  With such a configuration of the metal tube and the temperature sensing element, the time until the temperature of the temperature sensing element reaches the temperature of the atmospheric gas as the measurement target can be shortened, and the responsiveness of the temperature sensor can be improved. Can.

  Moreover, the heat insulating material is arrange | positioned in the state which covers the front end surface of the insulation support material in the circumference | surroundings of a temperature sensing element in the front end opening part of a metal tube. This heat insulating material is made of a ceramic material having a thermal conductivity lower than that of the ceramic material forming the insulating support material. Also by this, the heat conduction from the temperature sensing element to the metal tube and the heat conduction from the metal tube to the temperature sensing element can be suppressed.

  Specifically, when the temperature-sensitive element receives heat from the atmosphere gas or the like to be measured by heat radiation, heat transfer (heat convection) or the like, the heat insulating material is transferred to the metal pipe via the insulating support. Heat conduction can be suppressed. Further, in this case, the insulating support material can be made less susceptible to the heat from the atmosphere gas and the like by the heat insulating material. In addition, when the heat of the temperature sensitive element is released to the atmosphere gas or the like, the heat insulating material can suppress the heat conduction from the metal pipe to the temperature sensitive element via the insulating support material.

  Even with the configuration of such a heat insulating material, it is possible to shorten the time until the temperature of the temperature sensing element reaches the temperature of the atmosphere gas as the measurement target, and the responsiveness of the temperature sensor can be improved.

  So, according to the temperature sensor of the said one aspect, the responsiveness can be improved effectively.

  Note that the reference numerals in parentheses in each component shown in one aspect of the present invention indicate the correspondence with the reference symbols in the drawings in the embodiment, but the components are not limited to the contents of the embodiment.

FIG. 2 is a cross-sectional view showing the main part of the temperature sensor according to the first embodiment. FIG. 2 is a cross-sectional view showing the entire temperature sensor according to the first embodiment. III-III arrow sectional drawing of FIG. 1 which shows the principal part of the temperature sensor concerning Embodiment 1. FIG. 6 is a flowchart showing a method of manufacturing the main part of the temperature sensor according to the first embodiment. (A) Sheath tube molding, (b) Sheath tube molding having a reduced diameter portion, (c) Sheath tube molding and temperature sensitive element according to Embodiment 1, (d) Sheaths joined together Sectional drawing which shows the tube formation body and the temperature sensor intermediate body which is a temperature sensing element body. (A) tip metal tube and temperature sensor intermediate according to Embodiment 1, (b) temperature sensor intermediate with tip metal tube mounted, (c) temperature sensor intermediate filled with insulating support, (d) ) A sectional view showing a manufactured temperature sensor. FIG. 7 is a cross-sectional view showing the main part of a temperature sensor according to a second embodiment. FIG. 10 is a cross-sectional view showing the main part of a temperature sensor according to a third embodiment. FIG. 14 is a cross-sectional view showing the tip end portion of the main part of another temperature sensor according to the third embodiment; FIG. 14 is a cross-sectional view showing the tip end portion of the main part of another temperature sensor according to the third embodiment; FIG. 14 is a cross-sectional view showing the tip end portion of the main part of another temperature sensor according to the third embodiment; FIG. 14 is a cross-sectional view showing the tip end portion of the main part of another temperature sensor according to the third embodiment;

A preferred embodiment of the above-described temperature sensor will be described with reference to the drawings.
First Embodiment
As shown in FIG. 1, the temperature sensor 1 of the present embodiment includes a metal pipe 2, a temperature sensor 3, a pair of lead wires 31, an insulating support 4, and a heat insulator 5. The metal tube 2 is open at its tip as a tip opening 20. The temperature sensing element 3 is disposed at the distal end opening 20 and measures the temperature of the measurement target. The pair of lead wires 31 is connected (joined) to the temperature sensitive element 3. The insulating support material 4 is disposed in the metal pipe 2 and is made of a ceramic material that insulates the metal pipe 2 and the lead wire 31, and is for supporting the lead wire 31 on the metal pipe 2. The heat insulating material 5 is disposed around the temperature sensing element 3 in the tip opening 20 so as to cover the tip surface 401 of the insulating support 4 and has a thermal conductivity higher than that of the ceramic material constituting the insulating support 4. Is made of a low ceramic material.

  In the temperature sensor 1 of the present embodiment, the direction along the central axis of the metal tube 2 is referred to as an axial direction L. Further, in the axial direction L, the side on which the temperature sensing device 3 is disposed in the metal pipe 2 is referred to as a tip side L1, and the side opposite to the tip side L1 is referred to as a base end L2.

Hereinafter, the temperature sensor 1 of the present embodiment will be described in detail.
(Temperature sensor 1)
The temperature sensor 1 is for use in vehicles, and is used to measure the temperature of fluid flowing in an intake pipe or an exhaust pipe of an internal combustion engine (engine) in a car. The temperature sensor 1 of the present embodiment is disposed in the exhaust pipe and is used to measure the temperature of the exhaust gas flowing in the exhaust pipe. The temperature of the exhaust gas is used when performing combustion control of the internal combustion engine by an electronic control unit (ECU). For example, the temperature of the exhaust gas can be used to detect the temperature of the exhaust purification catalyst disposed in the exhaust pipe.

(Thermal sensor 3)
The temperature sensitive device 3 of the present embodiment is a thermistor device configured using a sintered body of a metal oxide as a thermistor material. The thermistor element can be an NTC (negative temperature coefficient) thermistor whose electric resistance value gradually decreases with an increase in temperature. In addition to this, the thermistor element has a positive temperature coefficient (PTC) thermistor whose electric resistance rapidly increases with a rise in temperature when the temperature exceeds a predetermined temperature, or an electric resistance decreases rapidly when the temperature exceeds the predetermined temperature. It can also be a CTR (critical temperature resistor) thermistor.

  Further, the temperature sensing element 3 may be a temperature measuring resistance element which is configured using platinum, copper, nickel or the like and whose electric resistance value increases as the temperature rises.

(Lead wire 31)
The pair of lead wires 31 is made of various metal materials having conductivity. As shown in FIG. 5D, the pair of lead wires 31 includes a pair of first lead portions 311 joined to the temperature sensing element 3 and a pair of second leads joined to the pair of first lead portions 311. It can consist of the part 312 and. In this case, the first lead portion 311 and the second lead portion 312 are joined by welding or the like in a state where they are butted or overlapped. Moreover, the lead wire 31 can also be made into one continuous metal wire.

  The lead wire 31 can be constituted by a platinum wire, a platinum alloy wire made of an alloy of platinum and another metal, a wire of Inconel (registered trademark) which is an alloy of nickel and another metal, or the like. Other than this, the lead wire 31 can also be constituted by a wire of SUS310S, an invar wire made of an alloy of iron and nickel, a super invar wire, a nickel wire, a nickel chromium wire, an iron chromium wire or the like.

(Metal pipe 2)
The metal tube 2 is also called a sheath tube and is made of a metal material. The metal tube 2 is formed in a cylindrical shape. As shown in FIG. 2, the metal tube 2 has the smallest outer diameter and inner diameter of the distal end side tube portion 21 in which the temperature sensing element 3 is disposed, and is a proximal end located on the proximal end side L2 than the distal end side tube portion 21. The outer diameter and the inner diameter of the side tube portion 22 are formed larger than the outer diameter and the inner diameter of the distal end side tube portion 21. The metal pipe 2 can be constituted by an Inconel (registered trademark) pipe. Besides this, the metal tube 2 can also be constituted by a tube of SUS310S, a tube of austenitic stainless steel, a tube of ferritic chromium steel, a tube of heat resistant cobalt alloy, a tube of nickel alloy, and a tube of iron chromium alloy. In order to facilitate the manufacture of the temperature sensor 1, the metal pipe 2 can be formed by appropriately joining a plurality of pipes by welding or the like.

(Housing 11)
As shown in FIG. 2, the metal pipe 2 is attached to a housing 11 attached to the exhaust pipe. The housing 11 includes a disposition hole 111 for disposing the pair of lead wires 31 and the terminal 13 of the connector 12, an outer peripheral screw 112 for attaching the temperature sensor 1 to the exhaust pipe, and a connector 12 for connecting the connector 12 to the housing 11. And a connecting portion 113. The distal end portion 131 of the terminal 13 of the connector 12 is inserted into the arrangement hole 111.

(Connector 12)
As shown in FIG. 2, the connector 12 made of insulating resin or the like is provided with a terminal (connection terminal) 13 to which the lead wire 31 is connected by welding. The tip portion 131 of the terminal 13 protrudes from the connector 12 so that the lead wire 31 is connected. The proximal end 132 of the terminal 13 is connected to a controller 10 that controls the operation of the temperature sensor 1. The controller 10 may be an engine control unit, or may be a sensor control unit (SCU) separate from the engine control unit. The terminal 13 is made of a conductive metal material.

(Insulating support 4)
As shown in FIG. 1, the insulating support 4 is made of a metal oxide such as magnesium oxide. The insulating support 4 can also be made of aluminum oxide or the like. The insulating support material 4 is formed as a sintered body obtained by sintering a ceramic powder disposed in the distal end side pipe portion 21 of the metal pipe 2. The insulating support 4 is filled in the distal end side pipe portion 21 of the metal pipe 2, and is not filled in the proximal end side pipe portion 22 of the metal pipe 2. In other words, the insulating support 4 is integrally disposed on the distal end side pipe portion 21 of the metal pipe 2 in a state of being continuous in the axial direction L. By filling the insulating support material 4 in the tip end side pipe portion 21 of the metal pipe 2, the pair of lead wires 31 is firmly supported by the metal pipe 2 in the tip end side pipe portion 21 of the metal pipe 2. The insulating support 4 is in contact with the outer periphery of the pair of lead wires 31 and the inner periphery of the distal end side pipe portion 21 of the metal tube 2. The insulating support 4 is disposed up to the tip end position on the inner periphery of the tip end side pipe portion 21 of the metal pipe 2.

(Insulating material 5)
As shown in FIG. 1 and FIG. 3, the temperature sensing device 3 is disposed at the center position of the cross section orthogonal to the axial direction L in the tip opening 20 of the metal tube 2. The heat insulating material 5 is disposed all around the side surface 302 of the temperature sensing element 3. In addition, the heat insulating material 5 is disposed in a state of covering the tip end surface 401 of the insulating support 4 and the tip end surface 201 of the metal pipe 2. By covering the front end surface 201 of the metal pipe 2 with the heat insulating material 5 as well, it is possible to make it difficult for heat to be transmitted from the exhaust gas as an atmospheric gas whose temperature is measured by the temperature sensor 1 to the metal pipe 2.

  A part of the side surface 302 of the temperature sensing element 3 and the tip end surface 301 project further to the tip end L 1 than the tip end surface 501 of the heat insulating material 5. The protrusion of the temperature sensing element 3 makes it easy for the temperature sensing element 3 to receive heat from the exhaust gas, and allows the heat to be easily dissipated from the temperature sensing element 3 to the exhaust gas.

  The heat insulating material 5 is made of fumed silica as a metal oxide. Fumed silica is a plurality of silica (silicon dioxide) particles formed in series. Fumed silica is a collection of white-based particles, and in particular, has the property of being difficult to absorb infrared radiation. Complicated and intricate pores are formed between the particles of silica. The heat insulating material 5 can also be composed of various foamed metal oxides. The foam metal oxide is a foam of metal oxide, and has pores formed when the blowing agent added into the molten metal foams.

  Moreover, the heat insulating material 5 can also be comprised by the ceramic wool comprised from the fiber body containing a silicon dioxide and aluminum oxide. Moreover, the heat insulating material 5 can also be comprised with a solid-like ceramic body, putting importance on heat resistance.

  The thermal conductivity of magnesium oxide constituting the insulating support 4 is about 59 W / (m · K). Moreover, the thermal conductivity of aluminum oxide is about 39 W / (m · K). On the other hand, the thermal conductivity of the fumed silica which comprises the heat insulating material 5 is about 0.05-0.1 W / (m * K) in the temperature range of 0-1200 degreeC. That is, the thermal conductivity of fumed silica is much smaller than the thermal conductivity of magnesium oxide, and fumed silica is excellent in thermal insulation (the property of blocking heat).

  In addition, the porosity of the ceramic material forming the heat insulating material 5 is larger than the porosity of the ceramic material forming the insulating support material 4. The porosity is expressed as the volume of pores contained in a unit volume of ceramic material. The heat insulating material 5 exhibits a high heat insulating effect by having many pores.

(Heat transfer material 6)
As shown in FIG. 1, a part of the side surface 302 as the tip side surface and the tip surface 301 of the temperature sensing element 3 of the present embodiment are covered with the heat transfer material 6 having a thermal conductivity higher than that of the insulating support 4 ing. A part of the side surface 302 of the temperature sensing element 3 and the tip surface 301 are not covered by the heat insulating material 5. The front end side surface is a surface located on the front end side L1 of the temperature sensing element 3 and is a surface exposed to the outside of the temperature sensor 1 in a state where the heat transfer material 6 described later is not provided. The distal end side surface may be configured by only the distal end surface 301.

  The heat transfer material 6 is made of a ceramic material (metal oxide) having a thermal conductivity higher than that of the ceramic material (metal oxide) forming the temperature sensing element (thermistor element) 3. The heat transfer material 6 is made of an oxide containing aluminum, silicon, zirconium or a composite thereof. By using the heat transfer material 6, it is possible to protect the temperature sensitive element 3 by preventing the heat transfer from the exhaust gas to the temperature sensitive element 3 and the heat transfer from the temperature sensitive element 3 to the exhaust gas as much as possible.

  Further, the heat transfer material 6 is made of a metal oxide excellent in heat resistance, and the heat resistance (heat resistant temperature) of the metal oxide forming the heat transfer material 6 is a metal oxide forming the temperature sensing element 3. Superior to the heat resistance (heat resistant temperature) of the object. Therefore, the temperature sensitive element 3 can be protected from heat by the heat transfer material 6, and the durability of the temperature sensitive element 3 can be improved.

(Production method)
Next, a method of manufacturing the main part of the temperature sensor 1 of the present embodiment will be described with reference to the flowchart of FIG.
As shown to Fig.5 (a), the sheath tube molded object 71 in which the metal tube 2, the 2nd lead part 312 of a pair of lead wire 31, and the insulation support material 4 were provided is prepared (step S1 of FIG. 4). The metal pipe 2 shows a tip side pipe portion 21 of the metal pipe 2. The molded sheath tube 71 is obtained by inserting the second leads 312 of the pair of lead wires 31 into the metal tube 2 and filling the gaps in the metal tube 2 with the insulating support 4. Next, as shown in FIG. 5 (b), diameter reduction processing is performed on the tip of the sheathed tube molded body 71 to form a diameter reduced portion 711 in which the metal tube 2 and the insulating support 4 are reduced in diameter (Step S2). ). Further, as shown in FIG. 5C, the temperature sensitive element body 72 in which the first lead portions 311 of the pair of lead wires 31 are joined to the temperature sensitive element 3 is prepared (step S3).

  Next, as shown in FIG. 5D, the first lead portions 311 of the pair of lead wires 31 in the temperature sensing element 72 and the second lead portions 312 of the pair of lead wires 31 in the sheath tube molded body 71 are Then, they are joined by laser welding to obtain a temperature sensor intermediate (step S4). Moreover, as shown to Fig.6 (a), the front-end metal pipe 2X used as the front-end | tip part of the metal pipe 2 is prepared (step S5). Next, as shown in FIG. 6B, the tip metal tube 2X is attached to the outer periphery of the portion of the metal tube 2 constituting the diameter-reduced portion 711 of the molded sheath tube 71 in the temperature sensor intermediate. Then, the tip metal tube 2X and the portion of the metal tube 2 constituting the reduced diameter portion 711 of the molded sheath tube 71 are joined by laser welding (step S6). Thus, the state in which the temperature sensing element 3 and the first lead portion 311 of the pair of lead wires 31 are disposed on the inner peripheral side of the distal end metal tube 2X is formed.

  Then, as shown in FIG. 6C, the space formed on the inner peripheral side of the tip end metal tube 2X is filled with a ceramic material (metal oxide) 4X for forming the insulating support 4 (step S7). ). Next, as shown in FIG. 6D, the heat insulating material 5 is provided on the tip end surface 401 of the insulating support 4 and the tip end surface 201 of the metal pipe 2 located around the temperature sensing element 3 (step S8). When the heat insulating material 5 is provided, in order to prevent the heat insulating material 5 from being provided on the tip side surface of the temperature sensing element 3, the tip side surface can be shielded by a shielding jig or the like. Further, as shown in the figure, the heat transfer material 6 is provided on the front end side surface of the temperature sensing element 3 (step S9). Thus, the assembly of the temperature sensor 1 is formed. Thereafter, the assembly is heated, the ceramic material forming the insulating support 4, the ceramic material forming the heat insulating material 5, and the ceramic material forming the heat transfer material 6 are sintered, and the main portion of the temperature sensor 1 is Manufactured.

  In addition, after the assembly of the temperature sensor 1 before the heat insulating material 5 and the heat transfer material 6 are provided is heated to sinter the insulating support material 4, the heat insulation material 5 and the heat transfer material 6 are mounted on this assembly. Can be provided to manufacture the main part of the temperature sensor 1.

(Action effect)
In the temperature sensor 1 of the present embodiment, the tip of the metal tube 2 is opened as the tip opening 20, and the temperature sensing element 3 is disposed at the center position of the cross section orthogonal to the axial direction L of the tip opening 20. ing. And since the curved-surface-shaped tip part (bottom part) is not formed in the tip position of metal tube 2, it becomes easy to enlarge distance of temperature sensitive element 3 and metal tube 2. Therefore, the temperature sensitive element 3 can be placed away from the metal tube 2 while being disposed at the tip end position of the temperature sensor 1. Thereby, the heat conduction from the temperature sensing element 3 to the metal pipe 2 and the heat conduction from the metal pipe 2 to the temperature sensing element 3 can be suppressed.

  Further, when the metal tube 2 is not present on the tip side L1 of the temperature sensing element 3, the temperature sensing element 3 receives heat from the exhaust gas as the measurement object by heat radiation, heat transfer (heat convection), etc., The temperature sensitive element 3 can be made more susceptible to heat. Further, when the heat of the temperature sensing element 3 is released to the exhaust gas by the absence of the metal tube 2 on the tip side L1 of the temperature sensing element 3, the heat remaining in the metal tube 2 is transmitted to the temperature sensing element 3. It can be hard to communicate.

  With such a configuration of the metal tube 2 and the temperature sensing element 3, the time until the temperature of the temperature sensing element 3 reaches the temperature of the exhaust gas as the measurement object can be shortened, and the response of the temperature sensor 1 is improved. It can be done.

  Further, the heat insulating material 5 is disposed around the temperature sensing element 3 in the distal end opening 20 of the metal pipe 2 so as to cover the distal end surface 401 of the insulating support 4 and the distal end surface 201 of the metal pipe 2. The heat insulating material 5 is made of a metal oxide having a thermal conductivity lower than that of the metal oxide constituting the insulating support 4. Also by this, the heat conduction from the temperature sensing element 3 to the metal pipe 2 and the heat conduction from the metal pipe 2 to the temperature sensing element 3 can be suppressed.

  Specifically, when the temperature sensing element 3 receives heat from the exhaust gas as the measurement object by heat radiation, heat transfer (heat convection) or the like, the heat insulating material 5 includes the metal pipe 2 through the insulating support 4 It is possible to suppress the heat conduction to. Further, in this case, the insulating support material 4 and the metal pipe 2 can be made less susceptible to the heat radiation from the exhaust gas, the heat transfer and the like by the heat insulating material 5. Moreover, when the heat of the temperature sensing element 3 is released to the exhaust gas, the heat insulating material 5 suppresses the heat remaining in the metal pipe 2 from being conducted to the temperature sensing element 3 through the insulating support 4. be able to.

  Even with the configuration of the heat insulating material 5 as described above, the time until the temperature of the temperature sensing element 3 reaches the temperature of the exhaust gas as the measurement object can be shortened, and the responsiveness of the temperature sensor 1 can be improved. .

  The responsiveness when measuring the temperature of the measurement object by the temperature sensor 1 is determined by how quickly the temperature of the temperature sensing element 3 follows the temperature of the measurement object. In the conventional temperature sensor, not only the temperature sensing element 3 rapidly reaches the temperature of the measurement target, but also the metal pipe 2 and the insulating support 4 existing around the temperature sensing element 3 also rapidly attain the temperature of the measurement target It is like that. Specifically, depending on the measurement object, the tip of the metal pipe 2 and the insulating support 4 adjacent to the tip are easily heated, so that the temperature sensing element 3 is also heated via these. .

  However, the heat capacity of the tip of the metal tube 2 is large. And since time required for temperature of a tip part of metal tube 2 to reach temperature of a measuring object is long, it turned out that time required for temperature of temperature sensitive element 3 to reach temperature of a measuring object also becomes long.

  In the temperature sensor 1 of the present embodiment, the front end portion of the metal tube 2 is removed to make it difficult for the metal tube 2 to be heated by the object to be measured and to make the temperature sensitive device 3 easy to be heated. Further, the heat sensing element 3 is selectively heated by making it difficult for the heat insulating material 5 to heat the distal end surface 401 of the insulating support 4 and the distal end surface 201 of the metal pipe 2.

  A technique for selectively heating such a temperature sensitive element 3 is not present in conventional temperature sensors. In the temperature sensor 1 of the present embodiment, the temperature of the temperature sensitive element 3 is made easy to follow the temperature of the exhaust gas by means of selectively heating the temperature sensitive element 3. Therefore, according to the temperature sensor 1 of the present embodiment, the responsiveness of the temperature sensor 1 can be effectively improved.

  In addition, the measurement range of the conventional temperature sensor is, for example, in the range of 25 to 900 ° C. by adopting a configuration in which the temperature sensing element 3 is heated together with the tip of the metal tube 2 It was difficult. On the other hand, the measurement range of the temperature sensor 1 of the present embodiment can be made wide as a range of -40 to 1050 ° C. by heating only the temperature sensitive element 3 as much as possible. In addition, when setting the measurement range of the temperature sensor 1 to 500 degreeC or more, the effect by the temperature sensor 1 of this form can be acquired notably.

Second Embodiment
The present embodiment shows a temperature sensor 1 in which the arrangement of the insulating support 4 is different from that of the first embodiment.
As shown in FIG. 7, the insulating support material 4 of the present embodiment is divided and disposed at a plurality of places in the axial direction L of the metal pipe 2. The insulating support 4 is disposed at a tip end of the tip side tube portion 21 of the metal pipe 2 in the axial direction L, and a first insulating support 4A that supports the pair of lead wires 31 to the metal pipe 2 at the tip. The base end portion of the front end side pipe portion 21 of the metal pipe 2 is disposed at the base end portion in the axial direction L, and the base end portion is made of the second insulating support 4B supporting the pair of lead wires 31 to the metal pipe 2.

  A cavity K by a gas such as air is formed in a portion between the first insulating support 4A and the second insulating support 4B as a portion where the insulating support 4 is not disposed in the metal pipe 2 . The cavity K may be in a state close to the atmospheric pressure or in a vacuum state lower than the atmospheric pressure. Further, the heat insulating material 5 is provided on the tip end surface 401 of the first insulating support 4A and the tip end surface 201 of the tip end side pipe portion 21 of the metal pipe 2. Further, the heat transfer material 6 is provided on the surface of the tip end side of the temperature sensing element 3.

  In the temperature sensor 1 of the present embodiment, the volume of the insulating support 4 is smaller and the heat capacity of the insulating support 4 is smaller than in the case of the first embodiment. Further, the cavity K is formed in the metal tube 2 at a position near the temperature sensing element 3. Due to the presence of the cavity K, the effect of heat insulation between the metal pipe 2 and the pair of lead wires 31 and between the metal pipe 2 and the temperature sensing element 3 is enhanced. Therefore, when the temperature sensing element 3 receives heat from the exhaust gas as the measurement target, heat conduction from the temperature sensing element 3 to the metal pipe 2 via the insulating support 4 is more effectively suppressed. Moreover, the heat conduction from the metal pipe 2 to the temperature sensing element 3 via the insulating support 4 is also effectively suppressed.

  Therefore, according to the temperature sensor 1 of the present embodiment, the time until the temperature of the temperature sensing element 3 reaches the temperature of the exhaust gas as the measurement object can be further shortened, and the responsiveness of the temperature sensor 1 is further improved. It can be done.

  The second insulating support 4 </ b> B may be provided at an intermediate portion between the distal end portion and the proximal end portion of the distal end side pipe portion 21 of the metal pipe 2. In addition, the second insulating support 4 </ b> B may be provided at an intermediate portion and a proximal end of the distal end side pipe portion 21 of the metal pipe 2.

  The other configurations, effects, and the like of the temperature sensor 1 of the present embodiment are the same as those of the first embodiment. Also in this embodiment, the constituent elements indicated by the same reference numerals as the reference numerals in the first embodiment are the same as those in the first embodiment.

Embodiment 3
In this embodiment, a modification of the temperature sensor 1 shown in Embodiments 1 and 2 will be described.
As shown in FIG. 8, the heat insulating material 5 is disposed not only on the tip end surface 401 of the insulating support 4 and the tip end surface 201 of the metal pipe 2, but also on the outer peripheral surface 202 of the tip side pipe portion 21 of the metal pipe 2. can do. In this case, heat radiation from the exhaust gas to be measured from the exhaust gas to the outer peripheral surface 202 of the metal pipe 2, heat transfer such as heat transfer, and heat radiation from the outer peripheral surface 202 of the metal pipe 2 to the exhaust gas, heat transfer, etc. Heat can be made more difficult to generate. Thereby, in particular, the effect of selectively heating the temperature sensing device 3 by the exhaust gas can be more easily obtained.

  Further, as shown in FIG. 9, in the temperature sensor 1 of Embodiments 1 and 2, the tip side surface of the temperature sensing element 3 may not be covered by the heat transfer material 6. Even when the heat transfer material 6 is not provided on the front end side surface of the temperature sensing element 3, the same function and effect as those of the first and second embodiments can be obtained.

  Further, as shown in FIG. 10, the distal end surface 301 of the temperature sensing element 3 may be recessed in the proximal end L2 relative to the distal end surface 501 of the heat insulating material 5, and is flush with the distal end surface 501 of the heat insulating material 5. It may be In this case, the side surface 302 of the temperature sensing element 3 is covered by the insulating support 4 and the heat insulating material 5, and the tip surface 301 of the temperature sensing element 3 is not covered by the heat insulating material 5. The distal end side surface is constituted only by the distal end surface 301. Also in this case, the same function and effect as those of the first and second embodiments can be obtained.

Further, as shown in FIG. 11, a part of the heat insulating material 5 may be disposed on the inner periphery of the distal end side pipe portion 21 of the metal pipe 2.
Further, as shown in FIG. 12, the first insulating support 4 </ b> A can be eliminated and the heat insulator 5 can be disposed on the inner periphery of the distal end side pipe portion 21 of the metal pipe 2. In this case, the material used for the heat insulating material 5 needs to be strong enough to support the temperature sensitive device 3 and the pair of lead wires 31 while having pores. Further, in this case, a part of the heat insulating material 5 may be disposed closer to the distal end L1 than the distal end opening 20, or may be disposed on the distal end surface 201 of the metal pipe 2.

  The temperature sensing element 3 can also be a temperature measurement contact of a thermocouple that utilizes a thermoelectromotive force generated by a temperature difference between a pair of contacts. In this case, the pair of lead wires 31 is configured as two types of metal wires made of different materials.

<Confirmation test>
In this test, when the thickness (μm) of the heat insulating material 5 and the thickness (μm) of the heat transfer material 6 in the temperature sensor 1 are changed, the response time (s) as the response of the temperature sensor 1 is measured. did.
The thickness of the heat insulating material 5 was changed to 10 μm, 20 μm, and 50 μm, and the thickness of the heat transfer material 6 was changed to 10 μm, 20 μm, 50 μm, 100 μm, and 200 μm. The temperature sensor 1 when changing each thickness was made into the test articles 1-15.

  Response time was determined as 63% response time. The target temperature for heating the temperature sensing element 3 of the temperature sensor 1 with the atmosphere gas is 1050 ° C., and the temperature sensing element 3 is 63 ° C. to about 650 ° C. (1030 ° C.). It calculated | required as time until it heats to about%). In addition, the atmosphere gas was in a stationary state with no flow velocity.

  In addition, for comparison, the conventional temperature sensor in which the end portion (bottom portion) is provided on the metal pipe 2 and the temperature sensing element 3 is disposed on the base end side of the end portion via the insulating support 4 The time was measured. This conventional temperature sensor was used as a comparison product. In the conventional temperature sensor, the heat insulating material 5 and the heat transfer material 6 are not used.

The results of measuring the response time for the test products 1 to 15 and the comparative product are shown in Table 1.

  The comparative product had a response time of 8 s, and it was found that the response was not excellent. On the other hand, in the test products 1 to 18, even if the thickness of the heat insulating material 5 is changed between 10 and 50 μm, the response time hardly changes, but as the thickness of the heat insulating material 5 increases, It turned out that the response time becomes short. Based on this result, the thickness of the heat insulating material 5 can be, for example, in the range of 10 to 100 μm.

  Moreover, in the test products 1-18, when the thickness of the heat-transfer material 6 was changed between 10-200 micrometers, it turned out that response time becomes long, so that the thickness of the heat-transfer material 6 becomes large. Even if the response time when the thickness of the heat transfer material 6 is 200 μm, the response time is about 1.8 s, so the response time is short compared to the comparison product, and it is confirmed that the response of the temperature sensor 1 is satisfied. did it. Based on this result, the thickness of the heat transfer material 6 can be, for example, in the range of 10 to 200 μm.

  Moreover, when the thickness of the heat-transfer material 6 is 0 micrometer, the case where the heat-transfer material 6 is not provided is shown. The response time when the heat transfer material 6 was not provided was shortest. Further, from the result that the response time becomes longer as the thickness of the heat transfer material 6 becomes larger, the effect of promoting the heat transfer by the heat transfer material 6 was not recognized. However, when the thermal conductivity of the heat transfer material 6 is higher than the thermal conductivity of the temperature sensing element 3, it is considered that when the thickness of the heat transfer material 6 is increased, an effect that the response time is less likely to be long is obtained. .

  From the above results, it was found that 10 [mu] m is sufficient for the thickness of each of the heat insulating material 5 and the heat transfer material 6 to make the response time about 1 s. However, each thickness of the heat insulating material 5 and the heat transfer material 6 can be set to be thicker than 10 μm in consideration of wear when used for a long time.

  The present invention is not limited to only the embodiments, and it is possible to configure different embodiments without departing from the scope of the invention. Further, the present invention includes various modifications, modifications within the equivalent range, and the like.

DESCRIPTION OF SYMBOLS 1 Temperature sensor 2 Metal pipe 20 Tip opening part 3 Temperature-sensitive element 31 Lead wire 4, 4A, 4B Insulating support material 5 Thermal insulation material 6 Heat-transfer material K Cavity

Claims (10)

A metal tube (2) whose tip is open as a tip opening (20);
A temperature sensitive element (3) disposed at the tip end opening for measuring a temperature;
A pair of lead wires (31) connected to the temperature sensitive element;
An insulating support (4, 4A, 4B), which is disposed in the metal tube and made of a ceramic material which insulates the metal tube from the lead wire, and for supporting the lead wire on the metal tube;
A ceramic material having a thermal conductivity lower than that of the ceramic material constituting the insulating support material, disposed in the state of covering the distal end surface (401) of the insulating support material around the temperature sensing element in the distal end opening A thermal insulator (5), and a temperature sensor (1).   A heat transfer material (6) made of a ceramic material having a thermal conductivity higher than that of the ceramic material constituting the temperature sensing element, in the temperature sensing element, the tip side surface (301, 302) not covered by the heat insulating material The temperature sensor according to claim 1, which is covered by   The temperature sensor according to claim 1 or 2, wherein the heat insulating material is also disposed on a tip surface (201) of the metal pipe.   The temperature sensor according to any one of claims 1 to 3, wherein the insulating support material is disposed at a tip end side pipe portion (21) of the metal pipe. The insulating support is divided into a plurality of locations in the axial direction (L) of the metal pipe, and
The temperature sensor according to any one of claims 1 to 3, wherein a cavity (K) is formed in a portion of the metal pipe where the insulating support is not disposed.   The temperature sensor according to any one of claims 1 to 5, wherein a distal end surface (301) of the temperature sensing element protrudes on a distal end side (L1) of a distal end surface (501) of the heat insulating material.   The temperature sensor according to any one of claims 1 to 6, wherein the heat insulating material is also disposed on an outer peripheral surface (202) of the metal pipe.   The temperature sensor according to any one of claims 1 to 7, wherein the porosity of the ceramic material forming the heat insulating material is larger than the porosity of the ceramic material forming the insulating support material.   The temperature sensor according to any one of claims 1 to 8, wherein the insulating support is made of magnesium oxide, and the heat insulating material is made of fumed silica.   The temperature sensor according to any one of claims 1 to 9, wherein the temperature sensing element comprises a thermistor element or a temperature measuring resistance element whose electric resistance value changes with temperature.

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