JPWO2013072961A1 - Temperature sensors and equipment - Google Patents

Abstract

To provide a temperature sensor that can be lengthened while suppressing an increase in cost, and a device including the temperature sensor.
The temperature sensor 1 includes a temperature sensing element 2 whose electrical resistance changes depending on temperature, a pair of lead wires 4 electrically connected to the temperature sensing element 2, and a portion connected to the temperature sensing element 2 and the temperature sensing element 2. A sealing material 5 for sealing the lead wires 4 within a predetermined range from each other, a heat-resistant wire 7 with a coating connected to a pair of lead wires 4 drawn from the sealing end 6 of the sealing material 5, A sensor element 10 having a ceramic material 9 covering from the toe 6 to the connecting portion 8 to which the lead wire 4 and the heat-resistant wire 7 with coating are connected is provided.

Description

  The present invention relates to a long temperature sensor capable of measuring a high temperature of, for example, 500 ° C. or higher.

  Temperature sensitivity of thermistors, etc. whose electrical resistance varies depending on the temperature in order to measure the temperature inside equipment such as electric ovens (electric heaters), radiant heaters, water heaters, combustion appliances, exhaust gas purifiers, boilers, burners, stoves, etc. A temperature sensor using a body is widely used. A sensor element used for such a temperature sensor includes a temperature sensor, a pair of lead wires connected to electrodes of the temperature sensor, and a sealing material made of heat-resistant glass that seals the temperature sensor. It is housed in a metal protective tube that protects the sensor element from vibration, external force, combustion gas, and the like.

  The present applicant has proposed a temperature sensor that can withstand use in a high-temperature atmosphere of, for example, 500 to 1000 ° C. in Patent Document 1. The temperature sensor of Patent Document 1 generates a leak current generated between lead wires when a conductive substance (a constituent element of the metal) evaporates from the metal protective tube that houses the temperature sensing element and fills between the lead wires. The purpose is to prevent. In order to achieve this object, the temperature sensor of Patent Document 1 covers a lead wire with a ceramic shield.

JP 2010-261860 A

  The temperature sensor of Patent Document 1 assumes a case where the length from the part (rear end) attached to the device to the temperature sensing body (front end) facing the measurement target is as short as about 50 mm, for example. However, depending on the device in which the temperature sensor is used, the length from the rear end to the front end may exceed 300 mm. When applying the ceramic shielding body of Patent Document 1 to such a long temperature sensor, there are the following problems. First, it is not easy to sinter and manufacture a long ceramic shielding body that is 100 times or more with respect to a diameter of several mm (approximately 2 to 3 mm), and the cost is significantly increased. The upper limit for easy and accurate fabrication is at most several tens of millimeters. If a large number of short ceramic shields of several tens of millimeters are connected, the overall length becomes long. However, since it is necessary to pass the lead wires through each of the many shields, the cost is still extremely high. It will be up.

  The present invention has been made based on such a technical problem, and an object thereof is to provide a temperature sensor that can be lengthened while suppressing an increase in cost, and a device in which the temperature sensor is incorporated.

  For this purpose, the temperature sensor of the present invention includes a temperature sensing element whose electrical resistance varies with temperature, a pair of lead wires electrically connected to the temperature sensing element, and the temperature sensing element and the temperature sensing element. A sealing material that seals the lead wire within a predetermined range from the formed portion, a heat-resistant wire with coating connected to a pair of lead wires drawn from the sealing end of the sealing material, and a sealing end And a protective material that covers up to the connecting portion where the lead wire and the heat-resistant wire with covering are connected.

According to the temperature sensor of the present invention, a long temperature sensor corresponding to the length of the coated heat-resistant wire can be manufactured by connecting the coated heat-resistant wire to the lead wire of the sensor element. Here, lead wires with high heat resistance such as platinum and platinum alloys that are connected to a temperature sensitive body that is exposed to high temperature are expensive. Therefore, if the lead wires are extended to the rear end side of the temperature sensor, the cost is reduced. Directly connected to the increase, the total cost including the coating for insulating the lead wire increases. Therefore, by shortening the length of the expensive lead wire and suppressing the cost, this lead wire has a high temperature atmosphere by connecting a heat resistant wire with a coating having heat resistance and insulation at a high temperature by coating. The lower insulation can be ensured at low cost.
This sheathed heat-resistant wire is prepared and connected to the lead wire. The heat-resistant lead wire is connected to a heat-resistant lead wire that is inferior in heat resistance, but is extended to the rear end side. Compared to a configuration in which a simple lead wire is covered with a large number of ceramic shields and protected from high heat, no cost is required.
In addition, the insulation from the sealing end to the connection portion is covered with the protective material, so that the insulation of the lead wire and the heat-resistant wire with the coating in a high temperature atmosphere can be ensured better. The minimum insulation required for the lead wire and the coated heat-resistant wire is to maintain insulation for a predetermined time (for example, several thousand to several hundred thousand hours) in a high temperature atmosphere.
In addition, the heat resistance of the coated heat-resistant wire can be improved by covering from the sealing end to the connection portion with the protective material. In the present specification, “heat resistance” means heat resistance deterioration strength.
Furthermore, since the length of a temperature sensor and the freedom degree of a use temperature range improve by selecting the length and material of a heat-resistant wire with a covering suitably, a temperature sensor can be provided according to the specification of various apparatuses.

  By the way, when the temperature gradient in use with respect to the length from the front end to the rear end of the temperature sensor is small, in order to sufficiently reduce the temperature at the rear end that may be touched by a person, the rear end has a corresponding length from the front end. It is necessary to be far away. That is, since the temperature sensor is required to be long, the temperature sensor of the present invention can make the lengthening effect stand out when the temperature gradient with respect to the length is small.

In the temperature sensor of the present invention, the protective material is a ceramic material including ceramic particles and a binding material that bonds the ceramic particles, and preferably covers the entire sealing material.
The ceramic material constituting the protective material is fluid including solvent before drying and curing. If the front end of the temperature sensor is immersed in this fluid ceramic material, the sealing material including the sealing end is sealed. A protective material is provided so as to cover the entire material and from the sealing end to the connection portion. By carrying out like this, a protective material can be provided easily rather than the case where a protective material is provided only from a sealing end to a connection part.
Or it is also preferable that a protective material shall have a ceramic material containing the ceramic particle and the binder which couple | bonds a ceramic particle, and the cap with which a ceramic material is filled inside. Thereby, since the shape of the protective material is determined by the shape of the cap, the shape stability of the protective material is excellent, and the yield is improved. When the protective material has a predetermined shape, predetermined heat resistance and insulation performance can be obtained.

In the temperature sensor of the present invention, it is preferable that the front end on the side where the temperature sensing element is disposed is closed and a metal protective tube into which the sensor element is inserted from the rear end is provided.
Since the sensor element is protected from vibration, external force, high heat, and combustion gas by the metal protective tube, it is possible to improve the durability of the temperature sensor over time.

In the temperature sensor of the present invention, it is preferable that the metal protective tube has a cylindrical body that forms a cylindrical portion connected to the front end, and a plate member that is welded to the peripheral portion of the cylindrical body and forms the front end.
Since a metal protective tube is also long with a long temperature sensor, it is possible to manufacture a metal protective tube by deep drawing that forms the plate material into a tube with the bottom (front end) closed using a die and a punch. Have difficulty. Even if it can be manufactured, there is a possibility that a desired thickness cannot be obtained at the front end of the metal protective tube.
Therefore, if the metal protective tube is composed of a cylindrical body and a plate material, and the front end of the metal protective tube is formed by welding a plate material of a desired thickness to the peripheral portion of the cylindrical body, a long metal protective tube (A bottomed tube with the front end blocked) can be easily manufactured, and the durability of the metal protective tube according to the thickness of the front end can be ensured.
Alternatively, instead of using the plate material as described above, a metal protective tube whose front end is blocked may be obtained by melting and solidifying the end of the cylinder body having both ends opened.

The above-described temperature sensor is incorporated in the device of the present invention.
ADVANTAGE OF THE INVENTION According to this invention, the apparatus in which a long temperature sensor is integrated can be provided, suppressing a cost increase. Moreover, it can respond to various apparatus specifications according to the length and material of the heat-resistant wire with a temperature sensor covering. Furthermore, the reliability of the device can be improved by ensuring the insulation and heat resistance of the temperature sensor.

  The temperature sensor and the device of the present invention can be lengthened while suppressing an increase in cost according to the length of the heat-resistant coated wire connected to the lead wire. In addition, insulation and heat resistance can be improved by covering from the sealing end to the connecting portion with a protective material.

It is a longitudinal cross-sectional view of the temperature sensor which concerns on embodiment of this invention. It is FIG. 1 enlarged view which shows the connection part of a lead wire and a heat-resistant wire with a covering. It is a figure which shows the manufacture procedure of a temperature sensor. It is a figure which shows schematic structure of the apparatus in which the temperature sensor of this embodiment is integrated. It is an enlarged view which shows the modification of this invention. It is an enlarged view which shows the modification of this invention.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
As shown in FIG. 1, the temperature sensor 1 of this embodiment is incorporated in a combustion device, and includes a sensor element 10 and a metal protective tube 15 that houses the sensor element 10.
The sensor element 10 includes a sensor element body 20 and a pair of heat-resistant wires 7 with a sheath connected to the pair of lead wires 4 of the sensor element body 20.

The sensor element body 20 includes a temperature sensing element 2 whose electrical resistance varies with temperature, a pair of lead wires 4 electrically connected to the temperature sensing element 2 via an electrode 3, and the temperature sensing element 2 and the electrode 3. It has the sealing material 5 which seals the lead wire 4 within a predetermined range. The lead wire 4 is drawn from the sealing end 6 of the sealing material 5.
In each drawing showing the cross section of the sensor element body 20, hatching of the temperature sensing element 2 and the sealing material 5 is omitted.

  Although it is preferable to use a thermistor as the temperature sensing element 2, those whose electric resistance varies with temperature can be widely applied. When used in a high temperature range of 500 to 1000 ° C., the thermistor includes, for example, Y, Cr, Mn, Ca and O, and the molar ratio of Y: Cr: Mn: Ca is 75 to 85: 7 to 10: It is preferable to use a metal oxide that is 7-10: 1-5. The temperature sensing element 2 composed of this metal oxide can measure the temperature up to a high temperature of 1000 ° C. or higher. However, this is only an example, and it goes without saying that other thermistors can be used.

  As the lead wire 4, platinum or a platinum alloy can be used. As the platinum alloy, one containing 1 to 20 wt% of iridium is preferable from the viewpoint of heat resistance.

The sealing material 5 is made of amorphous glass or crystalline glass. They can be used alone, but it is also possible to use a mixture of amorphous glass and crystalline glass so as to have a desired thermal expansion coefficient. The crystalline glass, for example, silicon oxide, calcium oxide, magnesium oxide, are preferred those composed of aluminum oxide, more specifically _{SiO 2: 30~60wt%, CaO:} 10~30wt%, MgO: 5 Those having a composition of ˜25 wt% and Al ₂ O ₃ : 0 to 15 wt% can be used in the present invention. Moreover, you may comprise using what added inorganic material powder to glass. Examples of the inorganic material powder added to glass include aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), yttrium oxide (Y ₂ O ₃ ), chromium oxide (Cr ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and the like. The metal oxide which comprises the temperature sensing body 2 is mentioned.

As the heat-resistant wire 7 with coating, for example, a core wire 71 having heat resistance is covered with an insulating tube (coating) 72 having higher heat resistance than that of the core wire 71, and insulation of the core wire 71 is performed even in a high temperature atmosphere of, for example, 500 ° C. or more. Those having sufficiently high insulation sufficient to ensure can be used.
Each of the core wire 71 and the insulating tube 72 has a heat resistant temperature corresponding to the operating temperature of the temperature sensor 1. Further, since the core wire 71 is covered with the insulating tube 72, the insulation of the core wires 71, 71 in a high temperature atmosphere can be ensured, that is, the metal protection tube 15 can be insulated and a short circuit between the wires can be prevented.
As the core wire 71, for example, Ni, a stainless alloy, a Ni-base superalloy, other heat resistant alloys, or the like can be used. These alloys contain a large amount of Ni and Cr in order to improve heat resistance. For example, JIS NCF600, which is an example of a Ni-base superalloy, contains about 75 wt% Ni and about 16 wt% Cr. Examples of the approximate normal heat resistance temperature of the core wire 71 by material are Ni: about 500 ° C., stainless alloy: about 600 ° C., and JIS NCF 600: about 800 ° C.
As the insulating tube 72, for example, a braided tube of glass fiber or ceramic fiber can be used. As the main component _can be exemplified by _{SiO 2, Al 2 O 3,} Si 3 N 4 or the like. Examples of the approximate heat resistance temperature of the insulating tube 72 by material are glass fiber braid: about 500 ° C., silica glass fiber braid: about 1000 ° C., ceramic fiber braid: about 1300 ° C.
For the purpose of improving insulation at high temperature of the coated heat resistant wire 7, a glass fiber or ceramic fiber is interposed between the core wire 71 and the insulating tube 72, or a tape made of mica paper and a backing material. May be interposed.
The heat-resistant wire 7 with coating is connected to the lead wire 4 at one end side. The covered heat-resistant wire 7 extends along the axial direction of the metal protective tube 15, and the other end drawn out of the metal protective tube 15 is connected to a measurement circuit (not shown). In addition, the heat-resistant wire 7 with a coating | cover and the measurement circuit may be connected via the other electric wire.

As shown in FIG. 2, the core wire 71 is exposed from the insulating tube 72 on one end side of the heat-resistant wire 7 with coating. The exposed end portion 71A of the core wire 71 is connected to the end portion 4A of the lead wire 4 drawn out from the sealing end 6, thereby providing a connection portion 8 between the lead wire 4 and the coated heat-resistant wire 7. ing.
In the present embodiment, the distal end portion 4A of the lead wire 4 and the distal end portion 71A of the core wire 71 are abutted against each other at the connecting portion 8 that is the boundary portion, and are welded using a laser. However, the distal end portion 4A of the lead wire 4 and the distal end portion 71A of the core wire 71 may be overlapped so that their outer peripheral surfaces are in contact with each other, and the connection is not limited to laser welding, but various types including an electric resistance heating method. The welding method can be adopted. When the lead wire 4 and the core wire 71 are abutted, there is an advantage that the cross-sectional diameter of the connecting portion 8 can be reduced. On the other hand, when the lead wire 4 and the core wire 71 are overlapped so that their outer peripheral surfaces are in contact with each other, the connection portion 8 is easily sandwiched between the electrodes, so that welding by an electric resistance heating method is facilitated.

The connecting portion 8 is covered with a ceramic material 9 as a protective material. The ceramic material 9 includes ceramic particles and an inorganic binder that bonds the ceramic particles to each other, and has high heat resistance of 1000 ° C. or higher and insulating properties. As the ceramic particles, for example, one having at least one of Al ₂ O ₃ , SiO ₂ , ZrO ₂ , ZrSiO ₄ , MgO, Y ₂ O ₃ , and AlN as a main component can be used. As the inorganic binder, ceramic, glass, metal alkoxide, or the like can be used.
Such a ceramic material 9 is provided on the entire sensor element body 20 including the connection portion 8, and covers from the sealing end 6 to the connection portion 8 and the outer peripheral portion of the sealing material 5. The ceramic material 9 also covers the core wire 71 exposed from the insulating tube 72.
The ceramic material 9 has fluidity including a solvent (for example, water) before being provided on the sensor element body 20, and is formed by being dried and cured by heating after being provided on the sensor element body 20. . For example, what is used as a coating material, an adhesive, or a sealing material can be used as the ceramic material 9.

Here, it is sufficient that at least the range from the sealing end 6 to the connection portion 8 is covered with the ceramic material 9. That is, the outer peripheral portion of the sealing material 5 may not be covered with the ceramic material 9. Further, when the core wire 71 is exposed at the end portion of the coated heat resistant wire 7, the exposed portion of the core wire 71 needs to be covered with the ceramic material 9. By being covered with the ceramic material 9 in this way, insulation of the lead wires 4 and 4 and the core wires 71 and 71 in a high temperature atmosphere is ensured, that is, insulated from the metal protective tube 15 and a short circuit between the wires is prevented. In addition, corrosion of the lead wire 4, the connection portion 8, and the core wire 71 of the heat-resistant wire 7 with coating in a high-temperature atmosphere is suppressed, so that heat resistance can be improved.
Here, the lead wire 4 has high heat resistance by using expensive platinum or a platinum alloy. Moreover, although it is inferior to the lead wire 4, the material which has high heat resistance is used for the core wire 71 of the heat resistant wire 7 with a coating | cover. By the way, in the connection part 8, although an alloy layer is formed in the interface of the lead wire 4 and the core wire 71 of the heat-resistant wire 7 with a coating, the heat resistance of the alloy layer is inferior compared with the heat resistance of the circumference | surroundings. For this reason, if the connection portion 8 is oxidized and deteriorated due to high heat, the signal from the temperature sensing element 2 is cut off at the connection portion 8, so that a correct temperature signal cannot be obtained or it is determined that the wire is disconnected. The sensor 1 needs to be replaced.
That is, when the lead wire 4 and the core wire 71 of the heat-resistant wire 7 with the coating are connected, the heat resistance deterioration in the interface alloy layer inevitably generated in the connection portion 8 is sufficiently compensated by the ceramic material 9, thereby interfacial alloy The heat resistance of the lead wire 4 and the core wire 71 including the layers can be improved, and the life of the temperature sensor 1 can be extended.

In addition, it is preferable that the ceramic material 9 is provided up to a position that hangs on the end of the insulating tube 72 as shown in FIG. Thereby, the insulation and heat resistance of the core wire 71 inside the insulating tube 72 are further improved.
The length from the sealing end 6 to the connection portion 8 is about 2 mm. In this embodiment, since the lead wire 4 and the core wire 71 are abutted and connected, the length of the lead wire 4 drawn out from the sealing end 6 corresponds to the length of the connecting portion 8 from the sealing end 6. To do. On the other hand, when the lead wire 4 and the core wire 71 are connected so that their outer peripheral surfaces overlap each other, the length from the sealing end 6 to the front end of the core wire 71 in the connecting portion 8 is the sealing end 6. Corresponds to the length of the connecting portion 8.

If the length from the sealing end 6 to the connecting portion 8 is as short as less than 0.5 mm, the sealing material 5 is deformed by heat when the lead wire 4 and the heat-resistant wire 7 with coating are connected by welding. Since there exists a possibility, it is preferable that it is 0.5 mm or more. Further, if the length of the lead wire 4 drawn out from the sealing end 6 is as short as less than 0.5 mm, it is sealed by mechanical stress such as when the lead wire 4 is trimmed as necessary. Since there is a risk of cracks in the stopper 5, it is preferably 0.5 mm or more.
And it is preferable that the length from the sealing end 6 to the edge part of the insulating tube 72 where the core wire 71 is exposed is 20 mm or less. If this length exceeds 20 mm, it is difficult to cover the sealing end 6 to the connection portion 8 with the ceramic material 9 with a predetermined thickness, so that the heat resistance and insulation by the ceramic material 9 may be impaired. is there.

The metal protective tube 15 is closed at the front end 15A on the side where the temperature sensing element 2 is disposed, and the rear end 15B is opened, so that the sensor element 10 housed therein is subjected to vibration, external force, high heat, combustion gas. Protect from. This metal protective tube 15 has a flange 16 as a mounting portion to the sensor mounting plate 14 on the rear end 15B side, and a length from the front end 15A (also referred to as the front end of the temperature sensor 1) to the flange 16. L is arbitrary, but is 400 mm as an example.
As a material of the metal protective tube 15, for example, a stainless alloy, a Ni-base superalloy, other heat resistant alloys, or the like can be used. For example, JIS NCF600, which is an example of a Ni-base superalloy, contains about 75 wt% Ni and about 16 wt% Cr.

Next, the structure of the combustion apparatus in which the temperature sensor 1 is incorporated will be described.
An example of the configuration of the combustion device is shown in the reaction chamber casing 17 containing the combustion reaction section H that is the measurement target of the temperature sensor 1 and is the highest temperature in the device, and outside the reaction chamber casing 17. A sensor mounting plate 14 to which the flange 16 of the temperature sensor 1 is mounted; a heat insulating material 18 provided between the reaction chamber casing 17 and the sensor mounting plate 14; It is provided on the outside and includes a device housing that houses devices and members (including the reaction chamber housing 17, the temperature sensor 1, and the sensor mounting plate 14) built in the device. The heat insulating material 18 suppresses the propagation of heat generated from the combustion reaction part H so that human harm does not occur due to the high temperature of the sensor mounting plate 14 that may be touched by a person. By having a thickness of about 20 to 50 mm, it has high heat insulation performance. The heat insulating material 18 is not limited to the position shown in FIG. 1, and is provided at an arbitrary position outside the reaction chamber casing 17 according to the structure of the device.

A procedure for manufacturing the temperature sensor 1 will be described with reference to FIG.
First, the lead wire 4 is joined to the electrode 3 of the manufactured temperature sensor 2. Next, for example, a glass material constituting the sealing material 5 is provided in a melted state around the temperature sensing element 2 by a known method, and is cooled and cured. What hardened | cured this glass material turns into the sealing material 5 which covers the thermosensitive body 2 and the predetermined range of the lead wire 4 (FIG. 3 (A)). Thereby, the sensor element body 20 is manufactured.

  Next, the core wire 71 of the heat-resistant wire 7 with the coating is welded and connected to the lead wire 4 (FIG. 3B). In addition, when the length from the sealing end 6 is longer than about 2 mm from the beginning, the lead wire 4 is cut to about 2 mm, and then the core wire 71 is welded. By collecting and reusing the separated lead wires 4 at this time, it is possible to contribute to cost reduction. If the sealing material 5 is formed after the core wire 71 is welded to the lead wire 4, the connecting portion 8 is reheated due to the influence of melting of the glass material (heat conduction from the molten glass material to the lead wire 4), This may cause oxidative degradation of the connecting portion 8, and therefore, it is preferable to weld the lead wire 4 after forming the sealing material 5.

  Further, the temperature sensor 1 is pulled up from the container after the front end of the sealing material 5 to the rear end of the connecting portion 8 are dipped in the ceramic material 9 before being dried and hardened in the container. Thereafter, in the process of heating and drying and hardening the ceramic material 9, the solvent is released and the ceramic particles 9 are provided by bonding the ceramic particles with the molten inorganic binder (FIG. 3C). ). When the sensor element 10 manufactured in this way is inserted into the metal protective tube 15 from the side where the temperature sensing element 2 is disposed (FIG. 3D), the coated heat-resistant wire 7 is formed from the rear end 15B of the metal protective tube 15. Withdrawn, the temperature sensor 1 is completed (FIG. 1). For example, the temperature sensor 1 may be fixed to the metal protective tube 15 by caulking the metal protective tube 15 near the rear end 15B.

  Here, the sensor element 10 is made of metal so that almost the same amount of heat as the front end 15A is conducted to the temperature sensing body 2 by abutting the sealing material 5 against the inner wall of the metal protective tube 15 on the front end 15A side. It is preferable that the protective tube 15 is assembled. However, when the temperature gradient of the temperature drop from the front end 15A to the rear end 15B is small, the temperature gradient in the vicinity of the front end 15A is small, so that a gap between the inner wall of the front end 15A and the sealing material 5 can be allowed. This is because the difference in the detected temperature of the temperature sensing element 2 that can occur depending on the presence or absence of the gap is small, so that the effect on the accuracy of temperature measurement is small.

  The flange 16 of the completed temperature sensor 1 is attached to the sensor mounting plate 14 and incorporated in the device (FIG. 1). The temperature sensor 1 may be supported by a supporting means (for example, a cylinder) provided between the sensor mounting plate 14 and the reaction chamber casing 17.

  When the temperature sensor 1 is attached to the sensor attachment plate 14, the front end 15 </ b> A of the temperature sensor 1 is arranged at or near the combustion reaction part H. The temperature of the front end 15A is, for example, 800 ° C. or higher. This high heat is conducted through the metal protective tube 15, the lead wire 4, and the core wire 71 toward the rear end 15 </ b> B of the temperature sensor 1. As shown in FIG. 1, the temperature distribution of the temperature sensor 1 of the present embodiment is 800 ° C. at the front end 15A, from the front end 15A, for example, from a position exceeding 1/2 of the length L to the rear end 15B. The temperature gradually decreases to 600 ° C, 500 ° C, and 400 ° C. This is merely an example, and the temperature in each part of the temperature sensor 1 from the front end 15A to the rear end 15B varies depending on the configuration of the temperature sensor 1 and the configuration of the device to be incorporated.

In the present embodiment, the distance from the sensor mounting plate 14 to the measurement position where the temperature sensing body 2 is disposed is long. For this reason, even if a conventional temperature sensor is incorporated in a device, the front end portion of the temperature sensor on which the temperature sensing element is arranged does not reach the measurement position, so that the temperature sensor needs to be elongated. If an attempt is made to manufacture such a long temperature sensor, the conventional structure in which the lead wire 4 is covered with a ceramic shield significantly increases the cost. Therefore, in the temperature sensor 1 of the present embodiment, insulation at high temperatures is possible. And the structure which connects the heat-resistant wire 7 with a heat | fever with heat resistance to the lead wire 4 is taken. High heat-resistant noble metal materials such as platinum and platinum alloy used for the lead wire 4 directly connected to the temperature sensing element 2 for detecting a high temperature are expensive, so the lead wire 4 is connected to the rear end 15B side of the temperature sensor 1. If it is extended, the cost is directly increased, and the total cost including the coating for insulating the lead wire is increased. For this reason, the insulation required for the range exposed to the high temperature from the vicinity of the front end 15A to the rear end 15B side by connecting the heat-resistant wire 7 with the sheath to the lead wire 4 while shortening the lead wire 4 to reduce the cost. And heat resistance.
Further, by covering the sealing end 6 to the connecting portion 8 and the core wire 71 exposed from the insulating tube 72 with the heat-resistant ceramic material 9, it is possible to ensure better insulation in a high temperature atmosphere and lead. By suppressing the corrosion of the core wire 71 of the wire 4 and the heat-resistant wire 7 with coating, the heat resistance of the lead wire 4 and the heat-resistant wire 7 with coating can be improved. As described above, the ceramic material 9 sufficiently compensates for the decrease in heat resistance in the interface alloy layer that inevitably occurs in the connection portion 8 between the lead wire 4 and the heat-resistant wire 7 with coating, and includes the interface alloy layer. It has the significance of improving the heat resistance of the wire 4 and the core wire 71.

In the case where the distance from the sensor mounting plate 14 to the measurement position where the temperature sensing element 2 is arranged is long, a thick heat insulating material 18 is provided between the sensor mounting plate 14 and the measurement position, for example, as in this embodiment. The temperature sensor 1 may be provided so as to penetrate the heat insulating material 18. Of course, this also applies to the case where it is necessary to keep the distance between the sensor mounting plate 14 and the measurement position sufficiently large in order to maintain the measurement object at a high temperature without being affected by outside air, as in the fuel cell described later. .
By the way, the temperature may not easily decrease from the measurement position to the sensor mounting plate 14. For example, a case where a fan for forced cooling is not built in the device is applicable. In addition, the provision of the heat insulating material 18 may be one of the factors that make it difficult to lower the temperature. In such a case, in order to sufficiently lower the temperature of the temperature sensor 1 in the vicinity of the sensor mounting plate 14 that may be touched by a person, further lengthening is required, so the effect of the present invention can be increased.

  The corrosion of the lead wire 4 and the core wire 71 includes electrolytic corrosion due to a leak current between the lead wires 4 and 4 and between the core wires 71 and 71. This electrolytic corrosion is described in detail in Patent Document 1 (Japanese Patent Laid-Open No. 2010-261860). In the present embodiment, even if the conductive material evaporates from the metal protective tube 15 in a high-temperature atmosphere, the conductive material is covered with the ceramic material 9, so that it is conductive between the lead wires 4 and 4 and between the core wires 71 and 71. Since no substance adheres and no leak current occurs through the conductive substance, electrolytic corrosion of the lead wire 4 and the core wire 71 can be prevented.

  The temperature sensor 1 of the present embodiment detects the temperature by the temperature sensing body 2 at the front end 15A disposed at or near the high temperature combustion reaction portion H of 800 ° C. or more, and human harm occurs from the front end 15A. In order to take out the detection signal outside the sensor mounting plate 14 that is set to a non-temperature, it is necessary to increase the length from the front end 15A to the rear end 15B. This lengthening requirement can be easily met by lengthening the coated heat resistant wire 7.

  In addition, since the coated heat resistant wire 7 has flexibility, it can be relaxed by bending stress due to a difference in thermal expansion that may occur between the front end portion of the sensor element 10 and the metal protective tube 15. For this reason, damage to the sensor element 10 can be prevented.

As an example of a combustion device in which the temperature sensor 1 is incorporated, a flame burner shown in FIG. 4 (A) and a fuel cell shown in FIG. 4 (B) are shown. Any of these controls the combustion reaction based on the temperature measured by the temperature sensor 1. Then, the temperature detected by the temperature sensor 1 and the set temperature are compared in a control circuit including an energization circuit, and the flame burner (A) controls the fuel and air to be input based on the comparison result, and (B ), The hydrogen and oxygen to be input are controlled based on the comparison result. Examples of flame burners include gas burners and petroleum burners, and types of fuel cells include solid oxide (SOFC), molten carbonate (MCFC), phosphoric acid (PAFC), solid high A molecular form (PEFC) can be illustrated. In particular, in solid oxide fuel cells, the object to be measured is high temperature, and due to the nature of the equipment, there is no built-in cooling fan and a thick heat insulating material is provided, so from the object to be measured to the sensor mounting plate surface. In addition to the long distance, the temperature gradient with respect to the length is often small. Therefore, since the request | requirement of lengthening is high, the temperature sensor of this invention can be used conveniently.
In addition, the temperature sensor 1 is not limited to a combustion device, and can be incorporated into various devices. For example, the temperature sensor 1 can be incorporated into an electric heater as shown in FIG. Specific examples of the electric heater include an oven, a radiant heater, a filter regeneration heater of an exhaust gas purification device (DPF: Diesel particulate filter), and the like.

The protective material in the present invention is not limited to the ceramic material 9 in the above embodiment, but includes a ceramic material 191 and a cap 192 filled with the ceramic material 191 as in the protective material 19 of FIG. May be. As the ceramic material 191, a material containing the same ceramic particles and binder as the above-described ceramic material 9 can be used.
When the protective material 19 is manufactured, the ceramic material 191 is put in a fluid state inside the cap 192 from the opened rear end 192B. Then, the ceramic material 191 is cured while the front end of the temperature sensor 1 inserted into the cap 192 is abutted on the inside of the front end 192A of the cap 192, and the cap 192, the ceramic material 191 and the front end portion of the sensor element 10 are integrated. Make it. In this way, since the shape of the protective material 19 is determined by the shape of the cap 192, the protective material 19 has better shape stability and better yield than the ceramic material 9 of the above embodiment. By making the protective material 19 into a predetermined shape, predetermined heat resistance and insulation performance can be obtained.

The metal protective tube in the present invention is not limited to the metal protective tube 15 described above, and may be configured as a metal protective tube described below. The metal protective tube described below can be easily manufactured even if it is long, and the thickness of the front end thereof is sufficient to ensure the durability of the metal protective tube.
The metal protective tube 25 in FIG. 6 has a cylindrical body 27 that forms a cylindrical portion that is continuous with the closed front end 25A, and a plate member 28 that is welded to the peripheral portion 271 of the cylindrical body 27 to form the front end 25A. The plate material 28 has a thickness sufficient to ensure the heat resistance of the front end 25A that is easily corroded by a high temperature.

  The front end 25A made of the plate material 28 is formed flat. For this reason, when the sensor element 10 is assembled to the metal protective tube 25, if the sealing material 5 is abutted against the inner wall of the front end 25 </ b> A, the detection points of the temperature sensor 2 when the temperature sensor 1 is assembled into the device are moved back and forth. The position is always constant without variation in direction. In the metal protective tube 15 of the above embodiment, when the sealing material 5 hits the inner wall side surface portion 15D before being abutted against the inner wall top portion 15C of the front end 15A, the detection point by the temperature sensing element 2 is shifted to the rear end side. Therefore, there is a possibility that the accuracy of temperature measurement may vary, but according to the metal protective tube 25 of FIG. 6, the accuracy of temperature measurement is stabilized.

  Furthermore, although the metal protective tube in this invention is abbreviate | omitted, the metal protective tube shown in FIG. 2 is melt | dissolved using a welding means and solidified using the welding means, although both ends opened. Similarly to 15, the front end 15 </ b> A may be closed. The front end of the metal protective tube is formed to have a desired thickness by collecting a material that has flowed by melting a part of the side wall of the cylindrical body. Note that when the temperature gradient of the temperature drop from the front end to the rear end of the metal protective tube is small, the temperature gradient in the vicinity of the front end is slight, and therefore the thickness of the front end may vary. This is because the difference in the detected temperature of the temperature sensing element 2 that can be caused by the difference in the thickness of the front end is slight, so the influence on the accuracy of temperature measurement is small.

  In addition to those described above, the configurations described in the above embodiments can be selected or modified as appropriate to other configurations without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Temperature sensor 2 Temperature sensing body 3 Electrode 4 Lead wire 4A Tip part 5 Sealing material 6 Sealing end 7 Heat-resistant wire 8 with covering 8 Connection part 9 Ceramic material 10 Sensor element 14 Sensor mounting plate 15 and 25 Metal protective tube 15A Front end 15B Rear end 15C Inner wall top portion 15D Inner wall side surface portion 16 Flange 17 Reaction chamber housing 18 Heat insulating material 19 Protective material 20 Sensor element body 25A Front end 27 Cylindrical body 28 Plate material 71 Core wire 71A Front end portion 72 Insulating tube 191 Ceramic material 192 Cap 192A Front end 192B Rear end H Combustion reaction part

In the temperature sensor of the present invention, it is preferable that the sealing material and the protective material are separate.
In the temperature sensor of the present invention, it is preferable that the front end on the side where the temperature sensing element is disposed is closed and a metal protective tube into which the sensor element is inserted from the rear end is provided.
Since the sensor element is protected from vibration, external force, high heat, and combustion gas by the metal protective tube, it is possible to improve the durability of the temperature sensor over time.
In the temperature sensor of the present invention, the protective material is preferably formed before being inserted into the metal protective tube.
In the temperature sensor of the present invention, it is preferable that the end portion of the lead wire and the end portion of the core wire included in the coated heat resistant wire are abutted against each other and welded at the connection portion.

Claims (7)

A temperature sensing element whose electrical resistance changes with temperature,
A pair of lead wires electrically connected to the temperature sensing body;
A sealing material that seals the temperature sensing element and the lead wire within a predetermined range from a portion connected to the temperature sensing element;
Heat-resistant wires with coatings connected to the pair of lead wires drawn out from the sealing end of the sealing material,
A temperature sensor comprising: a sensor element having a protective material covering from the sealed end to a connection portion where the lead wire and the heat-resistant wire with covering are connected.   The temperature sensor according to claim 1, wherein the protective material is a ceramic material including ceramic particles and a binding material that binds the ceramic particles, and covers the entire sealing material.   The temperature sensor according to claim 1, wherein the protective material includes a ceramic material including ceramic particles and a binding material that binds the ceramic particles, and a cap filled with the ceramic material.   The temperature sensor according to any one of claims 1 to 3, further comprising a metal protective tube into which the front end on the side where the temperature sensing element is disposed is closed and the sensor element is inserted from the rear end.   5. The temperature sensor according to claim 4, wherein the metal protective tube includes a cylindrical body that forms a cylindrical portion that continues to the front end, and a plate member that is welded to a peripheral portion of the cylindrical body to form the front end.   5. The temperature sensor according to claim 4, wherein the front end of the metal protective tube is closed by melting and solidifying an end portion of a cylindrical body having both ends opened.   A device in which the temperature sensor according to any one of claims 1 to 6 is incorporated.

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