Clamp-on Temperature Sensor

Abstract

To provide a clamp-on temperature sensor that can maintain stable and high-level temperature measurement accuracy even if retrofitted.SOLUTION: The present invention comprises: a temperature measurement resistor (216) having a temperature measurement part (202a) that measures the temperature of a portion which is in contact with piping; a temperature measurement resistive housing (220) that encloses the temperature measurement resistor (216); an insulating part that insulates between the temperature measurement resistive housing (220) and the temperature measurement resistor (216); attachment members (206, 208) which removably fixes the temperature measurement resistive housing (220) to the piping; a metal couplant (222) which is different from metal of the temperature measurement part and located between the temperature measurement part (202a) of the temperature measurement resistor and the piping; and a tightening part (212) that increases adhesion of the metal couplant (222) with the piping and tightens the attachment members (206, 208) to the piping.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a temperature sensor, and more particularly to a clamp-on temperature sensor that is detachably attached to a pipe after installation. [Background technology]

[0002] The inventors came up with the idea of ​​the present invention during the course of development to optimize ultrasonic flow rate detection devices including ultrasonic flow rate switches, concentration sensors, and temperature sensors for fluid management in factories.

[0003] For convenience of explanation, we will first explain ultrasonic flow switches. Ultrasonic flow switches that output ON / OFF signals are used in places where it is sufficient to detect whether a fluid is flowing through a pipe at a flow rate above a certain value, in other words, in places where an accurate value of the flow rate of the fluid flowing through the pipe is not required (Patent Document 1). Patent Document 1 also discloses a clamp-on ultrasonic flow switch. A clamp-on ultrasonic flow switch is a unit incorporating the elements included in the clamp-on ultrasonic flow switch that is retrofitted and installed at an appropriate location on the outer surface of the pipe. The clamp-on ultrasonic flow switch is detachable from the pipe.

[0004] Patent Document 1 discloses, as a typical example of a clamp-on ultrasonic flow switch, an integrated clamp-on ultrasonic flow switch having a configuration in which a set of first and second ultrasonic elements included in the ultrasonic flow switch is held by a single element holder. That is, in the integrated clamp-on ultrasonic flow switch disclosed in Patent Document 1, the first and second ultrasonic elements are waterproofly and integrally held within a single element holder, with the elements positioned relative to each other. The integrated clamp-on ultrasonic flow switch makes it easy for users to install the ultrasonic flow switch. In other words, it eliminates the need for users to perform the tedious task of installing the first and second ultrasonic elements on a pipe while positioning them relative to each other. Patent Document 2 discloses in detail the functional circuit blocks included in the clamp-on ultrasonic flow switch.

[0005] Next, the inventors studied what a temperature sensor should be in an ultrasonic flow rate detection device that includes an ultrasonic flow rate switch, a concentration sensor, and a temperature sensor. In particular, they studied what a temperature sensor to be incorporated into an ultrasonic flow rate detection device that uses a clamp-on ultrasonic flow rate switch should be. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-217734 [Patent Document 2] Japanese Patent Application Publication No. 2019-15549 Summary of the Invention [Problem to be solved by the invention]

[0007] The first method of installing a temperature sensor is to install the temperature sensor so that the temperature detection part, i.e., the temperature measuring part, is inserted into the liquid to be measured in the pipe. This is relatively easy to do when installing new pipes, but when installing the temperature measuring part in an existing pipe, it is not desirable because it requires work such as cutting the pipe.

[0008] Clamp-on ultrasonic flow switches have the advantage of being detachably retrofittable to desired locations on existing piping. To maximize this advantage, it would be desirable for temperature sensors to be retrofittable to existing piping, similar to clamp-on ultrasonic flow switches. Possible retrofitting methods include installing a thermocouple on the outer surface of the piping and securing it with adhesive tape or by soldering. Existing piping can be contaminated by the surrounding environment, for example, with oil adhering to the outer surface of the piping. Even if a thermocouple can be installed using adhesive tape on a contaminated piping, such as a temporary installation of a thermocouple, this may not pose any operational problems. However, while various installation methods have been proposed for clamp-on ultrasonic flow switches that enable long-term and stable operation, it is necessary to develop an installation method for clamp-on temperature sensors that can provide the same stable long-term operation as clamp-on ultrasonic flow switches.

[0009] An object of the present invention is to provide a clamp-on temperature sensor that can maintain stable and high temperature measurement accuracy even when it is retrofitted. [Means for solving the problem]

[0010] As mentioned above, the invention was conceived in the process of optimizing ultrasonic flow rate detection devices, including ultrasonic flow rate switches, concentration sensors, and temperature sensors, and the aim was to develop a clamp-on temperature sensor that could achieve advanced temperature measurement performance. The clamp-on temperature sensor according to the invention is not limited to application to ultrasonic flow rate detection devices, and it goes without saying that it can be widely implemented in society as a retrofit clamp-on temperature sensor with advanced temperature measurement capabilities.

[0011] According to the present invention, the above-mentioned technical problems are solved as follows: A clamp-on temperature sensor includes a temperature sensor head and an amplifier, and the temperature sensor head and the amplifier are connected by a communication cable, The temperature sensor head metala resistance temperature sensor having a temperature measuring part that measures the temperature of a part that comes into contact with the pipe; a temperature sensing resistance housing that surrounds the temperature sensing resistance element; an insulating portion that insulates the temperature sensing resistor housing from the temperature sensing resistor; a deformable metal couplant between the temperature measuring part of the resistance temperature sensor and the metal pipe, the metal couplant being different from the metal of the temperature measuring part and having adhesiveness to the metal pipe; The resistance temperature measuring housing The metal a mounting member that is detachably fixed to the piping; a clamping portion that attaches the metal couplant in a pressed state against the metal piping and clamps the mounting member to the metal piping; Equipped with The amplifier is an interface unit that receives an electrical signal obtained by the resistance temperature detector of the temperature sensor head; a temperature conversion unit that converts the electrical signal into a temperature signal; a display unit that displays the temperature signal converted by the temperature conversion unit; an output unit for outputting the temperature signal to an outside, The communication cable includes: a metal wire for supplying a current from the amplifier to the resistance thermometer of the temperature sensor head; The object is achieved by providing a clamp-on temperature sensor having a metal wire for measuring the potential difference across the resistance thermometer element of the temperature sensor head.

[0012] According to the present invention, a metal couplant is interposed between the temperature measuring unit and the piping, and the mounting member is tightened to press the temperature measuring unit against the piping. Variation of By increasing the adhesion between the temperature measuring part and the pipe, errors in the detected temperature can be reduced. A typical example of a metal couplant is tin or a tin alloy. Tin or a tin alloy can ensure adhesion even at room temperature. Furthermore, using a metal couplant such as tin or a tin alloy allows the clamp-on temperature sensor to be detached from the pipe, which has the advantage of being easy to work with and highly flexible in terms of attachment and detachment.

[0013] The effects and other objects of the present invention will become apparent from the following detailed description of the embodiments. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing the overall configuration of an ultrasonic flow rate detection device to which a refractive index type concentration sensor according to an embodiment of the present invention is preferably applied. [Figure 2] FIG. 2 is a diagram for explaining the configuration of a clamp-on ultrasonic flow switch included in the ultrasonic flow detecting device shown in FIG. [Figure 3] FIG. 1 is a perspective view of a belt-type clamp-on temperature sensor attached to a pipe. [Figure 4] FIG. 4 is a front view related to FIG. 3. [Figure 5] FIG. 4 is a side view related to FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] FIG. 1 is a perspective view of a box-type clamp-on temperature sensor attached to a pipe. [Figure 8] FIG. 8 is a front view related to FIG. 7. [Figure 9] FIG. 8 is a side view related to FIG. 7. [Figure 10] FIG. 10 is a cross-sectional view taken along line XX in FIG. 9. [Figure 11] This is a perspective view for explaining the overall configuration in which a relay amplifier is installed adjacent to but physically separated from a belt-type clamp-on temperature sensor using a mounting fixture (belt) for the belt-type clamp-on temperature sensor. [Figure 12] FIG. 12 is a side view related to FIG. [Figure 13] This is an oblique view to explain the overall configuration in which a relay amplifier is installed adjacent to but physically separated from a box-type clamp-on temperature sensor using a mounting fixture (C-shaped housing) for the box-type clamp-on temperature sensor. [Figure 14] FIG. 14 is a side view related to FIG. 13. [Figure 15] 1 is an overall block diagram of an ultrasonic flow rate detection device to which a refractive index type concentration sensor according to an embodiment of the present invention is preferably applied. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0015] Before explaining the refractive index type concentration sensor of the embodiment, we will explain an ultrasonic flow detection device optimized for coolant management in machine tools. The ultrasonic flow detection device consists of an ultrasonic flow switch, a concentration sensor, and a temperature sensor. The ultrasonic flow switch is an integrated clamp-on ultrasonic flow switch with a display function.

[0016] 1, reference numeral 2 denotes a coolant storage tank. A water-soluble cutting fluid diluted with water, i.e., coolant, is stored in the coolant storage tank 2. The coolant in the coolant storage tank 2 is supplied to a machine tool (not shown) through metal piping 4.

[0017] A clamp-on ultrasonic flow switch 6 is removably attached to the piping 4 as a retrofit. A concentration sensor 8 having a detection unit 8a inserted in, for example, the coolant storage tank 2 is connected to the clamp-on ultrasonic flow switch 6. The concentration sensor 8 preferably includes an indicator light 8b. A temperature sensor 10 installed at, for example, a connecting portion of the piping 4 is also connected to the clamp-on ultrasonic flow switch 6. The clamp-on ultrasonic flow switch 6 has a display unit, which will be described later, and these elements constitute an ultrasonic flow detection device 12.

[0018] 2 is a diagram illustrating a specific example of the clamp-on ultrasonic flow switch 6. The clamp-on ultrasonic flow switch 6 is composed of three components: a mounting base member 60, a measurement head member 62, and a switch indicator 64. The mounting base member 60 can be removably attached to an appropriate location on the piping 4. The measurement head member 62 includes first and second ultrasonic elements (see Patent Document 1) that constitute a flow rate detection unit, and this measurement head member 62 is removably attached to the mounting base member 60, and the mounting base member 60 keeps the measurement head member 62 in pressure contact with the piping 4.

[0019] A switch indicator 64 is attached to the measuring head member 62. In FIG. 2, (I) is a front view of the switch indicator 64, and (II) is a rear view of the switch indicator 64. A concentration sensor 8 and a temperature sensor 10 are connected to the switch indicator 64. The values ​​detected by the concentration sensor 8 and the temperature sensor 10 are displayed on the display section 64a of the switch indicator 64 as actual detected numerical values ​​without any processing such as calculation. The switch indicator 64 has a first indicator light 64b, and in addition, the measuring head member 62 is also provided with a second indicator light 62b.

[0020] The clamp-on ultrasonic flow switch 6 is most preferably configured as an integrated clamp-on ultrasonic flow switch. In the measuring head member 62, the first ultrasonic element and the second ultrasonic element are preferably integrally held by a single element holding portion (Patent Document 1).

[0021] Regarding the clamp-on temperature sensor 10 described above with reference to FIG. 1, two types of temperature sensors are available. One is a belt type, and the other is a box type. The clamp-on temperature sensor 10 illustrated in FIG. 1 is the latter box type. FIGS. 7 to 10, 13, and 14 are diagrams related to the box type. When it is necessary to distinguish between the belt type and the box type, the belt type clamp-on temperature sensor is designated by reference symbol 10A, while the box type clamp-on temperature sensor is designated by reference symbol 10B. FIGS. 3 to 6, 11, and 12 are diagrams related to the belt type. The belt type temperature sensor 10A is designed to be applied to pipes 4 with a medium or larger diameter. The box type temperature sensor 10B is designed to be applied to pipes 4 with a small diameter.

[0022] 3 to 6, the belt-type clamp-on temperature sensor 10A has a metal plate seat 204 that forms a seat for the temperature sensor body 202, and a pair of belt portions 206, 208, preferably made of metal, extending from one end and the other end of the metal plate seat 204. One of the belt portions 206 has a plurality of horizontal slits 210 (FIG. 3) aligned in the longitudinal direction. The diameter that can be enclosed by the pair of belt portions 206, 208, i.e., the effective length dimension of the pair of belt portions 206, 208, can be adjusted by operating a screw 212.

[0023] 6, the resistance temperature detector housing 220 surrounding the resistance temperature detector 216 is disposed between the metal plate seat 204 and the metal pipe 4, and the resistance temperature detector housing 220 can be tightened to the metal pipe 4 by operating the screw 212 to reduce the effective length of the pair of belt portions 206, 208. This allows the resistance temperature detector housing 220 to be pressed against the metal pipe 4, thereby fixing the belt-type clamp-on temperature sensor 10A to the metal pipe 4. This pressing force, i.e., tightening force, can be adjusted by the screw 212.

[0024] A temperature-measuring couplant 222 is interposed between the resistance temperature detector 216 and the pipe 4 (FIGS. 4 and 6). To ensure the belt-type clamp-on temperature sensor 10A can be easily attached to and detached from the pipe 4, the temperature-measuring couplant 222 is preferably made of metal. The metal of the temperature-measuring couplant 222 is selected to be different from the metal used in the temperature-measuring unit 202a, such as platinum (Pt). An example of the temperature-measuring couplant 222 is tin (Sn) or a tin alloy. By operating the screw 212, the pair of belt portions 206 and 208 press the temperature-measuring unit 202a against the pipe 4, which deforms the temperature-measuring couplant 222, thereby improving the adhesion between the temperature-measuring unit 202a and the pipe 4. For example, even if there are minute irregularities on the outer periphery of the pipe, the couplant 222 can conform to the irregularities and improve thermal coupling. In other words, the temperature detection error can be reduced by the adhesion caused by the deformation of the temperature measurement couplant 222 between the temperature measurement unit 202a and the pipe 4.

[0025] A desirable condition for the temperature-measuring couplant 222 is a Vickers hardness of 30 or less. Aluminum, with a Vickers hardness of about 45, and copper, with a Vickers hardness of about 50, are not desirable; lead-free solder, solder, gold, silver, or alloys of these, with a Vickers hardness of about 20, also meet this condition. Tin, even though hard, has a Vickers hardness of around 10, and also meets this condition.

[0026] The material of the temperature measuring couplant 222 must be excellent in terms of thermal conductivity and long-term reliability. Resin and rubber are not preferable because they tend to creep at high temperatures, and metal is preferred.

[0027] Even if the temperature measurement couplant 222 is plastically deformed without elastic deformation, it will be plastically deformed according to the outer shape of the piping, and will become an arc. Even if the temperature measurement couplant 222 is plastically deformed when detached after installation, when it is reinstalled on the piping, it can be firmly fixed to the piping with a belt or the like, so it can be detachably attached to the piping.

[0028] 7 to 10, the box-type clamp-on temperature sensor 10B will be described. The box-type clamp-on temperature sensor 10B has a metal housing 230. The metal housing 230 has a U-shape when viewed from the front, with one end closed and the other open. Like the belt-type clamp-on temperature sensor 10A, the box-type clamp-on temperature sensor 10B is thermally coupled and insulated from the resistance temperature detector 236 by a heat-dissipating filler (not shown) between the resistance temperature detector 236 and the resistance temperature detector housing 220, which surrounds the resistance temperature detector 236. The resistance temperature detector housing 220 is insulated by a heat insulating material 218, and is not affected by the ambient temperature.

[0029] 8 and 10, the pipe 4 is inserted into the U-shaped housing 230 and is sandwiched between the closed end of the U-shaped housing 230 and the temperature resistance housing 220. By operating a pair of left and right bolts 242, the temperature resistance housing 220 can be pressed against the pipe 4, thereby fixing the box-type clamp-on temperature sensor 10B to the pipe 4. This pressing force, or tightening force, can be adjusted by the pair of left and right bolts 242.

[0030] The above-mentioned temperature measurement couplant 222 is interposed between the resistance temperature detector 236 and the pipe 4 (FIGS. 8 and 10). By operating the left and right bolts 242, the temperature measurement resistance housing 220 including the resistance temperature detector 236 of the temperature sensor main body 234 is pressed against the pipe 4, which causes deformation of the temperature measurement couplant 222, thereby improving adhesion between the temperature measurement unit 234a and the pipe 4. In other words, the adhesion caused by deformation of the temperature measurement couplant 222 between the temperature measurement unit 234a and the pipe 4 can reduce temperature detection errors.

[0031] The belt-type clamp-on temperature sensor 10A and the box-type clamp-on temperature sensor 10B are configured to include a common relay amplifier 250. Figures 11 and 12 show the relay amplifier 250 incorporated into the belt-type clamp-on temperature sensor 10A. Figures 13 and 14 show the relay amplifier 250 incorporated into the box-type clamp-on temperature sensor 10B.

[0032] 11 and 12, the relay amplifier 250 is installed on the belt portion 208 that secures the temperature sensor body 202 of the belt-type clamp-on temperature sensor 10A to the pipe 4. As can be seen from FIGS. 11 and 12, the relay amplifier 250 has an elongated shape, and when the relay amplifier 250 is detachably secured to the belt portion 208, the longitudinal direction of the relay amplifier 250 is aligned with the longitudinal direction of the pipe 4. Interfaces are formed on one end face and the other end face of the relay amplifier 250 in the longitudinal direction.

[0033] The relay amplifier 250 includes a temperature converter 251 that converts the electrical signals obtained by the resistance temperature detectors 216 and 236 into temperature signals, and an amplifier display unit 250a that displays the temperature. The relay amplifier 250 also includes an amplifier indicator light 251 next to the amplifier display unit 250a. The amplifier indicator light 251 has green and red LEDs that turn on, turn off, or blink depending on the state of the temperature sensor 10. As shown in FIG. 12 , the relay amplifier 250 is provided with operation keys 255, which are up and down buttons, and a decision button 256. The display unit 250a can be selected using the operation keys 255 and the decision button 256 to adjust and set the threshold. The settings made by the relay amplifier 250 are closer to the measurements made by the temperature sensor 10 than the settings made by operating the buttons on the switch indicator 64. This is because the temperature measurement value, threshold, and ON / OFF output are displayed on the display and indicator light based on the settings made by the relay amplifier 250.

[0034] The settings that can be made on the Relay Amplifier 250 include the initial settings that are made when the power is turned on: language switching (Japanese, English, Simplified Chinese, German), output switching (NPN / PNP), unit switching (℃, Fahrenheit), and output content (ON / OFF signal / two analog signals).

[0035] An example of the display unit 250a in normal operation of the relay amplifier 250 is the display screen shown in Figure 14(b). The current temperature, 27.9°C, is shown on the right, with the upper limit set value on the top left and the lower limit set value on the bottom. Note that it is possible to set either a normally on mode that outputs an ON judgment within the upper or lower limit set value, or a normally off mode that outputs an OFF judgment.

[0036] During normal operation, the user can use the operation keys 255 to move the cursor to the upper limit setting value or the lower limit setting value, select it by briefly pressing the decision button 256, and then use the operation keys 255 to set the upper and lower setting values.

[0037] During normal operation, detailed settings can be changed by pressing and holding operation key 255. This includes switching between normally on and off, and switching the averaging time (for example, 10, 20, 60, or 300 seconds) for averaging and outputting the temperature over a specified period of time. In addition, settings can be changed at deeper levels of the settings hierarchy, allowing for more detailed settings for more experienced users.

[0038] The advanced settings that can be changed include hysteresis, offset, ambient temperature compensation, language switching, display inversion, screen brightness, key lock, PIN lock, and indicator light lighting mode. You can also check the current settings.

[0039] The amplifier indicator light 251 can be switched between modes such as lighting green when the judgment is ON and lighting red when the judgment is OFF, lighting green when the judgment is ON and turning off (nothing lights up) when the judgment is OFF, turning off (nothing lights up) when the judgment is ON and lighting red when the judgment is OFF, turning off both when the judgment is ON and when the judgment is OFF, etc. The amplifier indicator light 251 also functions as an indicator light for the occurrence of an error, and can also function as a warning light by flashing red when it detects a break in the signal line on the flow switch 6 side or when it detects an overcurrent.

[0040] The temperature sensor main body 202 is connected to one end surface of the relay amplifier 250 by a first cable 252, and an analog signal is supplied from the temperature sensor main body 202 to the relay amplifier 250, and the temperature is displayed on the display unit 250a. The other end surface of the relay amplifier 250 has an interface that outputs to the outside via a second cable 254, and the temperature signal is output to a switch display 64 (clamp-on flow switch 6). The switch display 64 of the clamp-on flow switch 6 has a multiprocessing display function, and the temperature information supplied to the switch display 64 of the clamp-on flow switch 6 through the relay amplifier 250 is managed as a history by the switch display 64.

[0041] Here, the entire system shown in Figure 1 will be explained using Figure 15. The temperature sensors 10A and 10B themselves consist only of resistance thermometers 216 and 236, and are connected to a relay amplifier 250 via four metal wires, or signal lines. A current is passed through the resistance thermometers 216 and 236, and the resulting voltage is detected to derive the temperature from the resistance value. However, the current is received via a power supply sent from the display via the relay amplifier. Therefore, the temperature sensors 10A and 10B do not include electronic components such as ICs. They simply transmit the resistance value to the relay amplifier 250.

[0042] The relay amplifier 250 has a temperature conversion unit 251 that converts the voltage difference obtained from the temperature sensor 10 into a temperature, and the temperature can be displayed on the display unit 250a of the relay amplifier 250. The digital signal converted into a temperature by the temperature conversion unit is sent to the clamp-on flow switch 6, and the temperature is displayed on the switch display 64 together with the flow rate of the flow switch 6.

[0043] The relay amplifier 250 can be configured to compensate for the ambient temperature of the temperature sensor 10. This compensates for the temperature value, taking into account the influence of the ambient temperature. The resistance thermometer 216 is surrounded by a housing made of insulating sponge 218, which prevents heat from being transferred to the resistance thermometer from the surrounding area other than the surface that contacts the pipe. However, since the ambient temperature affects the resistance thermometer depending on the type of pipe, compensation is performed according to the applicable pipe 4. Compensation parameters corresponding to the expected pipe material, such as iron or stainless steel, are prepared in advance and stored in the relay amplifier. Temperature compensation is performed on the measured temperature using the compensation parameters according to the pipe material selected by the user. This reduces the influence of the ambient temperature. The user can also choose not to compensate for the ambient temperature. For example, this is because the pipe may be insulated, making ambient temperature compensation unnecessary.

[0044] Referring to Figure 15, the refractive index type concentration sensor 8 has one signal cable to the outside. As shown in Figure 1, it is connected to the refractive index type concentration sensor 8 from the clamp-on ultrasonic flow switch 6 via a branch connector. It is connected to the ultrasonic flow switch 6 via a single cable including a power line and a communication line. The signal line splits into a power line and a communication IF section inside the refractive index type concentration sensor, and the power line supplies power to each circuit element in the refractive index type concentration sensor. The communication IF is used for bidirectional communication from the flow switch 6 to the concentration sensor 8 and from the concentration sensor 8 to the flow switch 6. The control section CB(m) controls the LED board (LED light source) 102 to irradiate light onto the prism, and the light reflected by the liquid is received by the CMOS board 106, which converts it into a refractive index depending on the light receiving position. A monitor PD 130 is provided near the LED light source 102 on the LED board to monitor the LED light emission amount. The current supplied to the LED light source 102 is adjusted according to the light emission amount of the LED light source 102, controlling the light emission amount to be constant. The indicator light 8b changes its lighting state depending on the light reception state and refractive index of the CMOS substrate 106. The refractive index type concentration sensor 8 has a temperature measurement circuit 40 including a thermometer on the liquid surface side. The temperature obtained by the thermometer in the temperature measurement circuit 40 may be used to display the fluid temperature. Furthermore, because the refractive index of the liquid changes with temperature, the obtained concentration may be corrected using the liquid temperature to correct for this temperature dependency.

[0045] 13 and 14, relay amplifier 250 is installed on the outer surface of U-shaped housing 230 that secures box-type clamp-on temperature sensor 10B to pipe 4. As can be seen from FIGS. 13 and 14, when relay amplifier 250 is detachably secured to U-shaped housing 230, the longitudinal direction of relay amplifier 250 is aligned with the longitudinal direction of pipe 4.

[0046] In the belt-type clamp-on temperature sensor 10A, the belt 208 constituting the mounting fixture can be used to detachably install the relay amplifier 250 while physically separated from the temperature sensor main body 202 that is in contact with the pipe 4, which is the heat source. In the box-type clamp-on temperature sensor 10B, the outer surface of the U-shaped housing 230 constituting the mounting fixture can be used to detachably install the relay amplifier 250 while physically separated from the temperature sensor main body 234 that is in contact with the pipe 4, which is the heat source.

[0047] As shown in Figure 2, a concentration sensor and a temperature sensor are connected to the switch indicator 64. Using two temperature sensors and a flow sensor, it is possible to measure the upstream and downstream temperatures and the flow rate of the fluid, thereby calculating the amount of heat and displaying it on the indicator. [Explanation of symbols]

[0048] 4. Pipe through which the liquid to be measured flows 10 Temperature Sensor 202a Temperature measuring section 216 Resistance thermometer 220 Resistance thermometer housing 206, 208 Belt part 212 Screw (tightening part) 222 Metal Couplant

Claims

1. A clamp-on temperature sensor includes a temperature sensor head and an amplifier, and the temperature sensor head and the amplifier are connected by a communication cable, The temperature sensor head a resistance temperature detector having a temperature measuring part that measures the temperature of a part that comes into contact with the metal pipe; a temperature sensing resistance housing that surrounds the temperature sensing resistance element; an insulating portion that insulates the temperature sensing resistor housing from the temperature sensing resistor; a deformable metal couplant between the temperature measuring part of the resistance temperature sensor and the metal pipe, the metal couplant being different from the metal of the temperature measuring part and having adhesiveness to the metal pipe; a mounting member that detachably fixes the temperature resistance housing to the metal pipe; a clamping portion that attaches the metal couplant in a pressed state against the metal piping and clamps the mounting member to the metal piping, The amplifier is an interface unit that receives an electrical signal obtained by the resistance temperature detector of the temperature sensor head; a temperature conversion unit that converts the electrical signal into a temperature signal; a display unit that displays the temperature signal converted by the temperature conversion unit; an output unit for outputting the temperature signal to an outside, The communication cable includes: a metal wire for supplying a current from the amplifier to the resistance thermometer of the temperature sensor head; a metal wire for measuring the potential difference between both ends of the resistance thermometer element of the temperature sensor head.

2. 2. The clamp-on temperature sensor according to claim 1, wherein the current to the resistance temperature detector is supplied from the amplifier, and the temperature sensor head does not include any electronic components.

3. 3. The clamp-on temperature sensor according to claim 1, wherein the amplifier comprises a relay amplifier equipped with an indicator light, and the indicator light of the relay amplifier is turned on, turned off, or flashes depending on the result of comparison between the temperature signal and a set value input by the user.

4. 4. The clamp-on temperature sensor according to claim 3, wherein the relay amplifier has an operation unit on a housing of the relay amplifier that accepts user input, and the set value for the temperature signal can be changed by input via the operation unit.

5. 5. The clamp-on temperature sensor according to claim 3, wherein the relay amplifier has a correction value according to the material of the metal pipe to which the temperature sensor head is attached, and outputs or displays a temperature signal based on the temperature signal converted by the temperature conversion unit and the correction value.

6. 6. The clamp-on temperature sensor according to claim 5, wherein the correction value is a pre-stored correction value selected by a user based on the material of the metal pipe.

7. 2. The clamp-on temperature sensor according to claim 1, wherein the mounting member is formed of a belt that surrounds the metal pipe.

8. 2. The clamp-on temperature sensor according to claim 1, wherein the mounting member is composed of a U-shaped housing surrounding the metal pipe and the temperature sensing resistor housing containing the temperature sensing resistor.

9. 2. The clamp-on temperature sensor of claim 1, wherein the metal couplant is tin or a tin alloy.

10. The clamp-on temperature sensor according to claim 1 , wherein the fastening portion is fastened to the metal pipe by fixing the mounting member to the metal pipe.

11. 2. The clamp-on temperature sensor of claim 1, wherein the mounting member is a belt that surrounds the metal pipe, and the amplifier is removably fixed using the belt while being physically separated from the resistance temperature detector.

12. The clamp-on temperature sensor of claim 1, wherein the mounting member is composed of a U-shaped housing that surrounds the metal piping and the resistance temperature detector housing that contains the resistance temperature detector, and the amplifier is removably fixed while physically separated from the resistance temperature detector using the side of the resistance temperature detector housing.

13. 2. The clamp-on temperature sensor according to claim 1, wherein the metal couplant is a metal having a Vickers hardness of 30 or less.

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