TW202417741A - Temperature sensor - Google Patents

Abstract

A temperature sensing system (100) comprising a choke (150) formed from a material with one or more temperature-dependent electrical properties, and a controller (110) configured to: pass an electrical signal through the choke, measure one or more electrical parameters of the electrical signal, wherein the one or more electrical parameters vary with temperature as a result of the one or more temperature-dependent electrical properties of the material from which the choke is formed, and determine a temperature of the choke based on the measured one or more electrical parameters.

Description

Temperature sensor

The present invention relates to a temperature sensor.

A variety of different types of temperature sensors are currently in commercial and scientific use. For example, one widely used type of temperature sensor is a thermocouple temperature sensor, which utilizes the temperature-dependent voltage characteristics of two dissimilar electrical conductors forming an electrical junction to sense temperature.

In one aspect, a temperature sensing system is provided, comprising: a choke formed from a material having one or more temperature-dependent electrical properties; and a controller configured to: pass an electrical signal through the choke; measure one or more electrical parameters of the electrical signal, wherein the one or more electrical parameters vary with temperature due to the one or more temperature-dependent electrical properties of the material forming the choke; and determine a temperature of the choke based on the measured one or more electrical parameters.

The choke may be a radio frequency choke.

The material may be ferrite.

The one or more temperature-dependent electrical properties may include resistivity and/or permeability.

The one or more electrical parameters may include one or more of: an amplitude response of the choke; a stationary-wave ratio of the electrical signal; and one or more scattering parameters of the electrical signal.

The temperature sensing system may further include an object, wherein the choke is positioned proximate to or in contact with the object such that the temperature determined by the controller corresponds to a temperature of the object.

The temperature sensing system may further include one or more heaters configured to heat the object, wherein the controller is configured to control the heaters based on the determined temperature.

The object may be a pipe of a vacuum pumping and/or abatement system.

The temperature sensing system may include a plurality of chokes, each choke being formed of a material having one or more temperature-dependent electrical properties, and the controller may be configured to: pass an electrical signal through the plurality of chokes; measure one or more electrical parameters of the electrical signal, wherein the one or more electrical parameters vary with temperature due to one or more temperature-dependent electrical properties of the material forming the plurality of chokes; and determine a temperature corresponding to at least one of the plurality of chokes based on the measured one or more electrical parameters.

The plurality of chokes may include a first choke and a second choke, wherein the behavior of the first choke in response to an electrical signal passing therethrough is temperature dependent in a first frequency range of the electrical signal, and the behavior of the second choke in response to an electrical signal passing therethrough is temperature dependent in a second frequency range of the electrical signal, the second frequency range being different from the first frequency range.

In another aspect, a vacuum pumping and/or abatement system is provided, which includes the temperature sensing system of the above aspect.

In yet another aspect, a method performed by a temperature sensing system is provided, the method comprising: passing an electrical signal through a choke formed from a material having one or more temperature-dependent electrical properties; measuring one or more electrical parameters of the electrical signal, wherein the one or more electrical parameters vary with temperature due to the one or more temperature-dependent electrical properties of the material forming the choke; and determining a temperature of the choke based on the measured one or more electrical parameters.

1 is a schematic diagram (not drawn to scale) showing a system 100 for sensing temperature according to a first embodiment. The system 100 includes a controller 110, an object 120, a plurality of heating elements (or heaters) 130, a first wire 140, a choke 150, a resistor 160, a second wire 170, an electromagnetic shield 180, and a thermal insulator 190.

The controller 110 includes a temperature sensing module 110a and a power module 110b. The temperature sensing module 110a is configured to transmit an electrical signal through a first wire 140 through a choke 150. In this embodiment, the electrical signal also passes through a resistor 160. The temperature sensing module 110a is also configured to monitor the characteristics of the electrical signal in order to determine a temperature. The power module 110b is configured to provide power to the heating element 130 through a second wire 170 to power the heating element so that it generates heat. In this embodiment, the power module 110b provides AC power to the heating element 130. The controller 110 can be configured to control the operation of the power module 110b based on the temperature sensed by the temperature sensing module 110a.

Object 120 is an object whose temperature is to be measured by system 100. In this embodiment, object 120 is a section of a pipe. The section of the pipe is configured to contain a fluid and transport the fluid therethrough. For example, the pipe may contain gas or liquid chemicals at various temperatures for industrial use. It will be appreciated that, in general, object 120 may be any type of object for which a temperature measurement is desired.

The plurality of heating elements 130 are configured to heat the object 120. The plurality of heating elements are positioned proximate to or in contact with the object 120 to provide heat to the object 120. In this embodiment, the heating elements 130 are electrically connected in parallel to each other.

The first wire 140 and the second wire 170 each include an electrical wiring for conducting electricity. For example, the first and second wires 140, 170 may include copper electrical wiring.

The choke 150 is an electrical component that blocks or limits the passage of AC power of certain frequencies while allowing other AC frequencies and/or DC to pass without restriction. The behavior of the choke 150 in response to an electrical signal passing therethrough is temperature dependent within a specific frequency range of the electrical signal. The behavior of the choke 150 is not temperature dependent or substantially temperature dependent at some or all frequencies outside the specific frequency range. In more detail, the choke 150 is formed of a material whose resistivity and/or permeability at a given electrical frequency passing through the material depends on the temperature of the material. In this embodiment, the material is a ferrite (e.g., Mn-Zn ferrite or Ni-ZN ferrite) and the choke 150 is a radio frequency (RF) choke. In this embodiment, the choke 150 is in the form of a ferrite bead. Thus, when an electrical signal of a given frequency is transmitted through the choke 150, the response of the choke 150 to the given electrical frequency varies depending on the temperature of the choke 150. The choke 150 is positioned proximate to or in contact with a portion of the object 120 such that the temperature of the choke 150 is substantially the same as or similar to the temperature of the portion of the object 120.

Resistor 160 is an impedance matching resistor connected in series with choke 150. The resistance of resistor 160 is selected to attempt to match the source and load impedances of the circuit formed by temperature sensing module 110a, first wire 140, choke 150 and resistor 160.

The electromagnetic shield 180 extends around a portion of the first wire 140 to shield the portion of the first wire 140 from external electromagnetic interference. For example, the electromagnetic shield 180 can be a sheath of conductive material that forms a Faraday cage around the portion of the first wire 140. It will be understood that the electromagnetic shield 180 is optional and can be omitted.

The thermal insulator 190 extends around at least a portion of the object 120, the heating element 130, the choke 150, the resistor 160, at least a portion of the first wire 140, and at least a portion of the second wire 170. The thermal insulator 190 is configured to thermally isolate the portion of the object 120 heated by the heater 130 and the choke 150 from external thermal influences. It will be understood that the thermal insulator 190 is optional and can be omitted.

The system 100 is configured to monitor the temperature of the choke 150 in order to estimate the temperature of a portion of the object 120 to which the choke 150 is positioned proximate or in contact. More specifically, the temperature sensing module 110a monitors one or more electrical characteristics of an electrical signal passing through the choke 150 via the first wire. The one or more electrical characteristics may represent a measure of an impedance mismatch between source and load impedances of a circuit formed by the temperature sensing module 110a, the first wire 140, the choke 150, and the resistor 160. The one or more electrical characteristics may include one or more of: an amplitude response of the choke 150; a stationary wave ratio (SWR) of the electrical signal; and one or more scattering parameters (e.g., S11, S12) of the electrical signal. The temperature sensing module 110a is configured to determine a temperature of the choke 150 based on one or more electrical characteristics.

In an exemplary embodiment, the temperature sensing module 110a is configured to determine a temperature of the choke 150 based on a SWR of the electrical signal passing through the choke 150 using some or all of the information in Table 1 below.

Table 1 below shows exemplary temperature values (Temp_C) mapped to SWR values (SWR) of a specific material (Mn-Zn ferrite or Ni-Zn ferrite) of the choke 150 at a specific frequency (Measure_at_hz) of the electrical signal passing through the choke 150 in Hertz. It will be appreciated that, in general, one skilled in the art will be able to obtain/use more data mapping the SWR value of a specific material at a specific frequency to a temperature value in order to configure the temperature sensing module 110a. Table 1

FIG. 2 is a schematic diagram (not drawn to scale) showing a system 200 for sensing temperature according to a second embodiment. The system 200 of the second embodiment is similar to the system 100 of the first embodiment, except that the system 200 of the second embodiment includes more than one choke 250a, 250b. The system 200 includes a controller 210, an object 220, a plurality of heating elements (or heaters) 230, a first wire 240, a first choke 250a, a second choke 250b, a resistor 260, a second wire 270, an electromagnetic shield 280, and a thermal insulator 290.

The controller 210 includes a temperature sensing module 210a and a power module 210b. The temperature sensing module 210a is configured to transmit an electrical signal through the first and second chokes 250a, 250b via the first wire 240. In this embodiment, the electrical signal also passes through the resistor 260. The temperature sensing module 210a is also configured to monitor the characteristics of the electrical signal in order to determine a temperature. The power module 210b is configured to provide power to the heating element 230 via the second wire 270 to power the heating element so that it generates heat. In this embodiment, the power module 210b provides AC power to the heating element 230. The controller 210 can be configured to control the operation of the power module 210b based on the temperature sensed by the temperature sensing module 110a.

Object 220 is an object whose temperature is to be measured by system 200. In this embodiment, object 220 is a section of a pipe. The section of the pipe is configured to contain a fluid and transport the fluid therethrough. For example, the pipe may contain gas or liquid chemicals at various temperatures for industrial use. It will be appreciated that, in general, object 220 may be any type of object for which a temperature measurement is desired.

The plurality of heating elements 230 are configured to heat the object 220. The plurality of heating elements are positioned proximate to or in contact with the object 220 to provide heat to the object 220. In this embodiment, the heating elements 230 are electrically connected in parallel to each other.

The first wire 240 and the second wire 270 each include an electrical wiring for conducting electricity. For example, the first and second wires 240, 270 may include copper electrical wiring.

Each of the first and second chokes 250a, 250b is an electrical component that blocks or limits the passage of some frequencies of AC power while allowing other AC frequencies and/or DC to pass without restriction.

The first choke 250a is responsive to the behavior of an electrical signal passing therethrough being temperature dependent in a first frequency range of the electrical signal. The first choke 250a is responsive to the behavior of an electrical signal passing therethrough being not temperature dependent or substantially temperature non-dependent at some or all frequencies outside the first frequency range. The second choke 250b is responsive to the behavior of an electrical signal passing therethrough being temperature dependent in a second frequency range of the electrical signal. The second choke 250b is responsive to the behavior of an electrical signal passing therethrough being not temperature dependent or substantially temperature non-dependent at some or all frequencies outside the second frequency range. The first frequency range is different from the second frequency range.

The first choke 250a is responsive to the behavior of an electrical signal passing therethrough in a second frequency range that is not temperature dependent or substantially temperature independent. The second choke 250b is responsive to the behavior of an electrical signal passing therethrough in a first frequency range that is not temperature dependent or substantially temperature independent. In more detail, each of the first and second chokes 250a, 250b is formed of a material whose resistivity and/or permeability at a respective given electrical frequency passing therethrough depends on the temperature of the material. In this embodiment, the material is a ferrite (e.g., Mn-Zn ferrite or Ni-ZN ferrite) and each of the first and second chokes 250a, 250b is a radio frequency (RF) choke. In this embodiment, each of the first and second chokes 250a, 250b is in the form of a ferrite bead.

When an electrical signal of a first frequency in a first frequency range is transmitted through the first choke 250a and the second choke 250b, the response of the first choke 250a to the first frequency varies depending on the temperature of the first choke 250a, but the response of the second choke 250b to the first frequency does not vary with the temperature or does not substantially vary with the temperature. When an electrical signal of a second frequency in a second frequency range is transmitted through the first choke 250a and the second choke 250b, the response of the second choke 250b to the second frequency varies depending on the temperature of the second choke 250b, but the response of the first choke 250a to the first frequency does not vary with the temperature or does not substantially vary with the temperature. Each of the first and second chokes 250a, 250b is positioned proximate to or in contact with a respective portion of the object 220 such that a temperature of each of the first and second chokes 250 is substantially the same as or similar to a temperature of the respective portion of the object 220 to which it is proximate or in contact.

Resistor 260 is an impedance matching resistor connected in series with the first and second chokes 250a, 250b. The resistance of resistor 260 is selected to attempt to match the source and load impedances of the circuit formed by the temperature sensing module 210a, the first wire 240, the first and second chokes 250a, 250b, and resistor 260.

The electromagnetic shield 280 extends around a portion of the first wire 240 to shield the portion of the first wire 240 from external electromagnetic interference. For example, the electromagnetic shield 280 can be a sheath of conductive material that forms a Faraday cage around the portion of the first wire 240. It will be understood that the electromagnetic shield 280 is optional and can be omitted.

The thermal insulator 290 extends around at least a portion of the object 220, the heating element 230, the first and second chokes 250a, 250b, the resistor 260, at least a portion of the first wire 240, and at least a portion of the second wire 270. The thermal insulator 290 is configured to thermally isolate the portion of the object 220 heated by the heater 230 and the first and second chokes 250a, 250b from external thermal influences. It will be understood that the thermal insulator 290 is optional and can be omitted.

The system 200 is configured to monitor the temperature of each of the first and second chokes 250a, 250b in order to estimate the temperature of the respective portion of the object 220 to which the first and second chokes 250 are positioned proximate to or in contact with. More specifically, the temperature sensing module 210a monitors one or more electrical characteristics of an electrical signal passing through the first and second chokes 250a, 250b via the first wire. The one or more electrical characteristics may represent a measure of an impedance mismatch between the source and load impedances of the circuit formed by the temperature sensing module 210a, the first wire 240, the first and second chokes 250a, 250b, and the resistor 260. The one or more electrical characteristics may include one or more of the following: an amplitude response of each of the first and second chokes 250a, 250b; a stationary ratio of the electrical signal; and one or more scattering parameters (e.g., S11, S22) of the electrical signal. The temperature sensing module 210a is configured to determine a temperature of each of the first and second chokes 250a, 250b based on the one or more electrical characteristics. For example, in a first case, an electrical signal at a frequency in a first frequency range passes through the first and second chokes 250a, 250b. As described above, because the response of the first choke 250a is temperature-dependent in the first frequency range, but the response of the second choke 250b is not (or substantially not) temperature-dependent in the first frequency range, the temperature sensing module 210a is configured to determine the temperature of the first choke 250a in a first case. In a second case, an electrical signal at a frequency in the second frequency range passes through the first and second chokes 250a, 250b. As described above, because the response of the second choke 250b is temperature-dependent in the second frequency range, but the response of the first choke 250a is not (or substantially not) temperature-dependent in the second frequency range, the temperature sensing module 210a is configured to determine the temperature of the second choke 250b in the second case. The system 100 may be configured to operate in a first case and then in a second case or vice versa to separately detect the temperatures of the first and second chokes 250a, 250b.

Similar to the embodiment described with reference to FIG. 1 , the temperature sensing module 210a may be configured to determine a temperature of the first and second chokes 250a, 250b based on a SWR of the electrical signal passing through the first and second chokes 250a, 250b using some or all of the information in Table 1 below. Again, it will be appreciated that, in general, one skilled in the art will be able to obtain/use more data that maps SWR values of a particular material at a particular frequency to temperature values in order to configure the temperature sensing module 110a for use with multiple chokes having temperature-dependent responses in different frequency ranges.

It will be appreciated that in other embodiments, even more chokes may be added having temperature-dependent responses in still further different frequency ranges in order to detect temperatures at even more locations, based on the principles described above with respect to the first and second chokes 250a, 250b.

FIG. 3 is a flow chart showing a method 300 performed by each of the systems of FIG. 1 and FIG. 2 . At step 310 , the method begins. At step 320 , a controller of the system passes an electrical signal through a choke. The choke is formed of a material having one or more temperature-dependent electrical properties. At step 330 , the controller measures one or more electrical parameters of the electrical signal, wherein the one or more electrical parameters vary with temperature due to one or more temperature-dependent electrical properties of the material forming the choke. At step 340 , the controller determines a temperature of the choke based on the measured one or more electrical parameters.

Therefore, a temperature sensing system is provided.

Advantageously, the temperature sensing system described above does not use a thermocouple-based temperature sensor. A thermocouple-based temperature sensor tends to use a relatively large amount of cabling, which tends to be cumbersome and takes up a relatively large amount of space. By allowing a thermocouple-based temperature sensor to be avoided, the system described above tends to use less cabling and is more easily modular. This in turn tends to simplify maintenance of the system and reduce installation errors.

It will be appreciated that various modifications/deviations may be made to the above-described embodiments without departing from the scope of the present invention. For example, although the specific example given in Table 1 above maps SWR values to temperature values, one skilled in the art will also be able to use/obtain similar data for other temperature-dependent electrical parameters such as amplitude response and scattering parameters to determine temperature.

100: system 110: controller 110a: temperature sensing module 110b: power module 120: object 130: heating element 140: first wire 150: choke 160: resistor 170: second wire 180: electromagnetic shielding 190: thermal insulation 200: system 210: controller 210a: temperature sensing module 210b: power module 220: object 230: heating element 240: first wire 250a: first choke 250b: second choke 260: resistor 270: second wire 280: electromagnetic shielding 290: thermal insulation 300:Method 310:Step 320:Step 330:Step 340:Step

FIG. 1 is a schematic diagram (not drawn to scale) showing a system for sensing temperature; FIG. 2 is a schematic diagram (not drawn to scale) showing another system for sensing temperature; and FIG. 3 is a flow chart showing steps performed by each of the systems of FIG. 1 and FIG. 2.

100:System

110: Controller

110a: Temperature sensing module

110b: Power module

120: Objects

130: Heating element

140: First Wire

150: Choke

160: Resistor

170: Second wire

180: Electromagnetic shielding parts

190: Thermal insulation

Claims (12)

A temperature sensing system includes: a choke formed of a material having one or more temperature-dependent electrical properties; and a controller configured to: pass an electrical signal through the choke; measure one or more electrical parameters of the electrical signal, wherein the one or more electrical parameters vary with temperature due to the one or more temperature-dependent electrical properties of the material forming the choke; and determine a temperature of the choke based on the measured one or more electrical parameters. A temperature sensing system as claimed in claim 1, wherein the choke is a radio frequency choke. A temperature sensing system as claimed in any preceding claim, wherein the material is ferrite. A temperature sensing system as in any preceding claim, wherein the one or more temperature-dependent electrical properties include resistivity and/or permeability. A temperature sensing system as in any preceding claim, wherein the one or more electrical parameters include one or more of: an amplitude response of the choke; a stationary-to-wave ratio of the electrical signal; and one or more scattering parameters of the electrical signal. A temperature sensing system as in any preceding claim, further comprising an object, wherein the choke is positioned proximate to or in contact with the object such that the temperature determined by the controller corresponds to a temperature of the object. The temperature sensing system of claim 6, further comprising one or more heaters configured to heat the object, wherein the controller is configured to control the heaters based on the determined temperature. A temperature sensing system as claimed in claim 6 or 7, wherein the object is a pipe of a vacuum pumping and/or abatement system. A temperature sensing system as claimed in any preceding claim, wherein: the temperature sensing system comprises a plurality of chokes, each choke being formed of a material having one or more temperature-dependent electrical properties, and the controller being configured to pass an electrical signal through the plurality of chokes, measure one or more electrical parameters of the electrical signal, wherein the one or more electrical parameters vary with temperature due to the one or more temperature-dependent electrical properties of the materials forming the plurality of chokes; and determining a temperature corresponding to at least one of the plurality of chokes based on the measured one or more electrical parameters. A temperature sensing system as claimed in claim 9, wherein the plurality of chokes include a first choke and a second choke, wherein: The behavior of the first choke in response to an electrical signal passing therethrough is temperature-dependent in a first frequency range of the electrical signal; and The behavior of the second choke in response to an electrical signal passing therethrough is temperature-dependent in a second frequency range of the electrical signal, the second frequency range being different from the first frequency range. A vacuum pumping and/or abatement system comprising a temperature sensing system according to any of the preceding claims. A method performed by a temperature sensing system, the method comprising: passing an electrical signal through a choke formed of a material having one or more temperature-dependent electrical properties; measuring one or more electrical parameters of the electrical signal, wherein the one or more electrical parameters vary with temperature due to the one or more temperature-dependent electrical properties of the material forming the choke; and determining a temperature of the choke based on the measured one or more electrical parameters.