GB2595334A - Heating apparatus - Google Patents

Heating apparatus Download PDF

Info

Publication number
GB2595334A
GB2595334A GB2102630.7A GB202102630A GB2595334A GB 2595334 A GB2595334 A GB 2595334A GB 202102630 A GB202102630 A GB 202102630A GB 2595334 A GB2595334 A GB 2595334A
Authority
GB
United Kingdom
Prior art keywords
heating element
heating
reference resistor
electrically
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB2102630.7A
Other versions
GB2595334B (en
GB202102630D0 (en
Inventor
Victor Thompson Brian
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TRANSVEND Ltd
TRANSVEND Ltd
Original Assignee
TRANSVEND Ltd
TRANSVEND Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TRANSVEND Ltd, TRANSVEND Ltd filed Critical TRANSVEND Ltd
Priority to GB2102630.7A priority Critical patent/GB2595334B/en
Publication of GB202102630D0 publication Critical patent/GB202102630D0/en
Publication of GB2595334A publication Critical patent/GB2595334A/en
Application granted granted Critical
Publication of GB2595334B publication Critical patent/GB2595334B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B1/00—Details of electric heating devices
    • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
    • H05B1/0227—Applications
    • H05B1/023—Industrial applications
    • H05B1/0244—Heating of fluids
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
    • G05D23/2401—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor using a heating element as a sensing element
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B1/00—Details of electric heating devices
    • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
    • H05B1/0227—Applications
    • H05B1/023—Industrial applications
    • H05B1/0236—Industrial applications for vehicles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/78—Heating arrangements specially adapted for immersion heating
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K2217/00—Temperature measurement using electric or magnetic components already present in the system to be measured
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/021—Heaters specially adapted for heating liquids
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/035—Electrical circuits used in resistive heating apparatus

Abstract

A heating apparatus 110 comprises a heating element 115 and a controller 120. The controller is configured to switch the heating apparatus between a heating mode and a measuring mode. In the heating mode, the heating element is electrically coupled to a heating circuit 106. The heating circuit provides an electricity supply to electrically heat the heating element. In the measuring mode, the heating element is electrically decoupled from the heating circuit and the temperature of the heating element is determined based on a resistance of the heating element while electrically decoupled from the heating circuit. The measuring mode may comprise electrically coupling the heating element to a measuring circuit 125, comprising a current source 305, a voltage sensor 315 and a reference resistor 310 having a known resistance. The current source may sequentially apply a test current to the heating element and to the reference resistor and the voltage sensor may measure corresponding voltage drops across the heating element and reference resistor, allowing measurement of the resistance of the heating element, and hence enabling its temperature to be determined.

Description

Heating Apparatus Technical Field
The present invention relates to a heating apparatus comprising a heating element, a vehicle comprising the heating apparatus and a method for determining the temperature of the heating element in the heating apparatus.
Background
A heating apparatus, such as a water heater, typically includes a heating element for heating water in a vessel, a temperature sensor for measuring the temperature of the water and a controller. The controller controls the supply of electricity to the heating element and interrupts the electricity supply when the temperature of the water measured by the temperature sensor reaches a desired value (typically at or around the boiling point of the water), in order to prevent the heating apparatus from overheating and being damaged or even catching fire. Therefore, the temperature sensor is an important component for safe operation of the heating apparatus.
Existing temperature sensors are usually based on mechanical (bimetallic) or electronic thermostats which measure the temperature of the water or steam produced by the boiling water. Therefore, the temperature sensor relies on the presence of water in the vessel to turn off the electricity supply to the heating element, and there is a risk that the heating element might overheat if there is no water in the vessel (for example, if the water has run out, or an operator has forgotten to fill the vessel with water).
Therefore, there is a need for a way to reduce the risk of overheating in a heating apparatus.
Summary
According to a first aspect of the invention, there is provided a heating apparatus comprising a heating element and a controller. The controller is configured to switch the heating apparatus between a heating mode and a measuring mode. In the heating mode, the heating element is electrically coupled to a heating circuit. The heating circuit is configured to provide an electricity supply (for example, from a battery of a vehicle) to electrically heat the heating element. In the measuring mode, the heating element is electrically decoupled from the heating circuit and the temperature of the heating element is determined based on a resistance of the heating element while electrically decoupled from the heating circuit.
Determining the temperature of the heating element based on the resistance of the heating element while the heating element is electrically decoupled from the heating circuit provides a way to directly measure the temperature of the heating element, rather than relying on an indirect measurement of water or steam temperature to infer the temperature of the heating element. Measuring the temperature of the heating element directly in this way reduces the risk of overheating the heating element, particularly in instances where there is no water in a vessel being heated by the heating element (for example, when the water has run out, or an operator has forgotten to fill the vessel with water).
In a prior art heating apparatus, where a temperature sensor is arranged to measure the temperature of water in the vessel remote from the heating element, or the temperature sensor relies upon steam produced by boiling water, the temperature sensor may never indicate that a maximum temperature for the heating element has been reached or exceeded if there is no water in the vessel. As a result, if there is no water in the vessel, the heating element could overheat, risking damage to the heating apparatus and fire. In contrast, the claimed invention in this situation would be able to directly detect the overheating of the heating element in the absence of water, shutting off the electricity supply to the heating element to prevent overheating.
The measuring mode may comprise electrically coupling the heating element to a measuring circuit. The heating mode may comprise electrically decoupling the heating element from the measuring circuit. This may increase the efficiency of the heating system by reducing power dissipation through the measuring circuit when not being used for actively measuring the temperature of the heating element.
The measuring circuit may comprise a current source, a voltage sensor, and a reference resistor having a pre-determined (i.e., known) resistance. During the measuring mode, the current source may be configured to apply a test current to the heating element and the voltage sensor may be configured to measure a voltage drop across the heating element that is produced by the applied test current. Also during the measuring mode, the current source may be configured to apply the test current to the reference resistor and the voltage sensor may be configured to measure a voltage drop across the reference resistor that is produced by the applied test current. The test current applied to the heating element may be substantially the same as the test current applied to the reference resistor. The controller may be configured to determine the resistance of the heating element based on the voltage drop across the heating element that is produced by the applied test current, the voltage drop across the reference resistor that is produced by the applied test current and the pre-determined (known) resistance of the reference resistor.
By using a reference resistor of a pre-determined (known) resistance to determine the resistance of the heating element, the resistance of the heating element can be accurately determined even if the electricity supply to the heating element varies in output during the measuring mode. Being able to cope with variations in the electricity supply (such as changes in the supply voltage) is advantageous when the electricity is being supplied from an unregulated supply, such as a battery, where the voltage from the supply is not constant, but varies over time (like when a battery ages or is discharged). For example, when the heating apparatus is installed in a vehicle (such as a van, lorry, caravan, campervan or the like) and electricity may be supplied to the heating apparatus from a battery (such as the vehicle battery).
The current source of the measuring circuit may provide less power than the electricity supply. This prevents a substantial heating effect to the heating element and the reference resistor during temperature measurements which might otherwise adversely affect the temperature measurement.
The voltage sensor may be configured to measure the voltage drop across the heating element during a first measurement period and the voltage drop across the reference resistor during a second measurement period that is different to the first measurement period. Measuring the voltage drop across the heating element and reference resistor during separate measurement periods means that the apparatus could perform the measurements using a single voltage sensor.
The heating apparatus may further comprise a heating element switch in series with the heating element. The heating apparatus may further comprise a reference resistor switch in series with the reference resistor. The switches may be any kind of electronic switch, such as a transistor or relay. Advantageously, the switches may be field effect transistors which enable fast switching and minimise voltage drops.
During the heating mode, the controller may be configured to close the heating element switch to electrically couple the heating element to the heating circuit (to supply electricity to the heating element) and open the reference resistor switch to electrically decouple the reference resistor from the heating circuit. This may substantially reduce or prevent energy dissipation through the reference resistor when not in use during the heating mode.
The measuring mode may comprise a first measurement period and a second measurement period. During the first measurement period, the controller may be configured to close the heating element switch and open the reference resistor switch to electrically couple the heating element to the current source and the voltage sensor, and electrically decouple the reference resistor from the current source and the voltage sensor, in order to measure the voltage drop solely across the heating element. During the second measurement period, the controller may be configured to open the heating element switch and close the reference resistor switch to electrically decouple the heating element from the current source and the voltage sensor, and electrically couple the reference resistor to the current source and the voltage sensor, in order to measure the voltage drop solely across the reference resistor.
Also during the measuring mode, the controller may be configured to compare the temperature of the heating element with a threshold temperature to detect overheating of the heating element. Determining overheating of the heating element itself provides more safety over using a thermostat or other temperature measuring devices remote from the heating element which might not accurately reflect the temperature of the heating element. The controller may be further configured to prevent electrical heating of the heating element when the temperature of the heating element is above the threshold temperature, which prevents electrical heating of the heating element which might lead to overheating.
The heating apparatus may further comprise a current sensor. The current sensor may be configured to measure the current through the heating element. The controller may be configured to compare the current through the heating element with a threshold current, for example, to detect short-circuits, or monitor the operation of other components within the heating apparatus, (such as monitoring operation of a mode switching device that switches the heating apparatus between the heating mode and the measuring mode). The controller may be further configured to prevent electrical heating of the heating element when the current through the heating element is above the threshold current, for example, to prevent electrically heating the heating element under conditions deemed unsafe.
The electricity supply may be unregulated. For example, the electricity supply may be from a battery, such as the battery associated with a vehicle (like a van, lorry, caravan, campervan, etc).
According to a second aspect of the invention, there is provided a vehicle comprising the heating apparatus according to the first aspect. The vehicle may be a van, lorry, caravan, campervan, or the like and the heating apparatus may be installed permanently or temporarily in the vehicle. The vehicle may provide the electricity supply to electrically power the heating apparatus, for example, from a battery associated with the vehicle (such as the vehicle battery that is powering the vehicle, or another battery to provide auxiliary power to the vehicle, or a battery for specifically powering the heating apparatus).
According to a third aspect of the invention, there is provided a method for determining a temperature of a heating element in a heating apparatus. The method comprises switching the heating apparatus between a heating mode and measuring mode. The heating mode comprises electrically coupling a heating element to a heating circuit. The heating circuit is configured to provide an electricity supply to electrically heat the heating element. The measuring mode comprises electrically decoupling the heating element from the heating circuit, and determining a temperature of the heating element based on a resistance of the heating element while electrically decoupled from the heating circuit.
The measuring mode may comprise electrically coupling the heating element to a measuring circuit. The heating mode may comprise electrically decoupling the heating element from the measuring circuit.
During the measuring mode, the method may further comprise applying a test current from a current source to the heating element and measuring, using a voltage sensor, a voltage drop across the heating element. Also, during the measuring mode, the method may further comprise applying the test current from the current source to a reference resistor having a pre-determined resistance and measuring, using the voltage sensor, a voltage drop across the reference resistor. Also, during the measuring mode, the method may further comprise determining a resistance of the heating element based on the voltage drop across the heating element, the voltage drop across the reference resistor and the pre-determined resistance of the reference resistor.
The current source may have less power than the electricity supply.
The method may further comprise using the voltage sensor to measure the voltage drop across the heating element during a first measurement period and the voltage drop across the reference resistor during a second measurement period.
The method may further comprise providing a heating element switch in series with the heating element and a reference resistor switch in series with the reference resistor.
During the heating mode, the method may comprise closing the heating element switch to electrically couple the heating element to the heating circuit, and opening the reference resistor switch to electrically decouple the reference resistor from the heating circuit.
The measuring mode may comprise a first measurement period and a second measurement period. During the first measurement period, the method may comprise closing the heating element switch and opening the reference resistor switch to electrically couple the heating element to the current source and the voltage sensor, and electrically decouple the reference resistor from the current source and the voltage sensor, in order to measure the voltage drop solely across the heating element. During the second measurement period, the method may comprise opening the heating element switch and closing the reference resistor switch to electrically decouple the heating element from the current source and the voltage sensor, and electrically couple the reference resistor to the current source and the voltage sensor, in order to measure the voltage drop solely across the reference resistor.
The method may further comprise comparing the temperature of the heating element with a threshold temperature, and preventing electrical heating of the heating element when the temperature of the heating element is above the threshold temperature.
The method may further comprise measuring the current through the heating element using a current sensor, comparing the current through the heating element with a threshold current, and preventing electrical heating of the heating element when the current through the heating element is above the threshold current.
The electricity supply may be unregulated. The electricity supply may be from a battery associated with the vehicle.
Brief Description of the Drawings
The invention shall now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 shows a block diagram of a vehicle comprising a heating apparatus according to an embodiment of the invention; Fig. 2 is a flow chart of a method of switching the operation of the heating apparatus between a measuring mode and a heating mode; Fig. 3 shows a block diagram of the heating apparatus in more detail; Fig. 4 is a flow chart illustrating a method of operating the heating apparatus in the measuring mode; Fig. 5 shows a block diagram of the heating apparatus configured for operation during a first measurement period of the measuring mode; Fig. 6 shows a block diagram of the heating apparatus configured for operation during a second measurement period of the measuring mode; Fig. 7 shows a block diagram of the heating apparatus configured for operating in a heating mode; and Fig. 8 shows in a block diagram a vehicle comprising a heating apparatus with an optional current sensor.
Detailed Description
Fig. 1 illustrates a heating apparatus 110 installed in a vehicle 100 (such as a van, lorry, caravan, campervan, etc) for providing hot water for drinking, cooking, cleaning and other tasks.
The heating apparatus 110 has an electrical heating element 115, such as a resistance heating coil, for heating hot water in a vessel 113. The heating element 115 can be electrically coupled to heating circuit 106 which provides an electricity supply to electrically heat the heating element 115. In this example, the heating circuit 106 is supplied by battery 105. Battery 105 may be the same battery used to power vehicle 100 or another battery provided for auxiliary power in the vehicle 100.
To prevent the heating element 115 from overheating, the temperature of the heating element 115 is determined by measuring the resistance of the heating element 115 with the measuring circuit 125 and controller 120. The resistance of the heating element 115 will change as a function of temperature and therefore a measurement of the resistance of the heating element 115 can be used to infer the temperature of the heating element 115.
The heating element 115 is selectively connected to the heating circuit 106 by switching device 112 which is controlled by controller 120, to selectively switch between a measuring mode for measuring the temperature of the heating element 115 and a heating mode for heating the heating element 115. In the measuring mode, the switching device 112 connects the measuring circuit 125 to the heating element 115 while the heating circuit 106 is disconnected from the heating element 115. In the heating mode, the switching device 112 connects the heating circuit 106 to the heating element 115 while disconnecting the measuring circuit 125. The controller 120 controls the operation of the switching device 112 to control the flow of electricity from the battery 105 via the heating circuit 106 to the heating element 115 according to the measured temperature as compared with a temperature threshold, only switching to heating mode to permit the heating element 115 to be heated while the temperature of the heating element 115 is at a safe temperature, such as below an overheating temperature threshold.
Fig. 2 illustrates a process 200 of the controller 120 switching the heating apparatus 110 between a measuring mode and a heating mode in more detail. At step 205, the controller 120 switches the heating apparatus 110 to measuring mode. At step 210, the temperature of the heating element 115 is determined by the controller 120 based on the resistance of the heating element 115. At step 215, the controller 120 compares the determined temperature of the heating element 115 to the overheating temperature threshold: * If the controller 120 determines, at step 220, that the temperature of the heating element 115 is below the overheating temperature threshold, the controller 120 proceeds to step 225 where the controller 120 switches the heating apparatus 110 to heating mode, in order to electrically heat the heating element at step 230. The process 200 is repeated (optionally after a delay) by the controller 120 switching back into measuring mode at step 205 to continue to monitor for changes in temperature (for example, to monitor the progress of heating a volume of water).
* If the controller 120 determines (at step 220) that the temperature of the heating element 115 is above the overheating temperature threshold, the controller 120 proceeds to step 235, where the controller 120 does not switch the heating apparatus 110 to heating mode. The controller 120 proceeds back to step 210 (optionally after a delay) to continue to monitor the temperature of the heating element 115, only switching back into heating mode once the temperature of the heating element 115 has cooled below the overheating temperature threshold (for example, once a volume of water has cooled below its desired temperature).
While the temperature of the heating element 115 is below the overheating temperature threshold, the heating apparatus 110 tends to operate in heating mode for a substantially longer period than operating in measuring mode in order to reduce heat loss during the measuring mode while the heating element 115 is not being heated.
Fig. 3 shows a block diagram of the heating apparatus 110 showing more detail of the measuring circuit 125 and the switching device 112. The measuring circuit 125 includes a current source 305, a reference resistor 310 and a voltage sensor 315. The current source 305 can apply a test current to the reference resistor 310 or the heating element 115 during the measuring mode, with the voltage sensor 315 measuring the voltage drop across the heating element 115 or the reference resistor 310 caused by the test current. The reference resistor 310 is of a pre-determined (known) resistance. The resistance of the heating element 115 can then be determined on the basis of the measured voltage drops across the heating element 115 and reference resistor 310 given that the resistance of the reference resistor 310 is known.
As discussed in relation to Fig. 1, the heating apparatus 110 has a switching device 112 which is operated by the controller 120 to switch the heating apparatus 110 between the heating mode and the measuring mode. Fig. 3 shows the components of the switching device 112, which includes a mode switching device 323, a heating element switching device 324 in series with the heating element, and a reference resistor switching device 325 in series with the reference resistor 310. The mode switching device 323 is a two-way switch (such as a relay) operable by the controller 120. The mode switching device 323 selectively connects either: (a) the heating circuit 106 (and hence battery 105) or (b) the current source 305. The mode switching device 323, the heating element switching device 324 and the reference resistor switching device 325 allow the heating element 115, reference resistor 310, current source 305 and heating circuit 106 including battery 105 to be interchangeably connected according to the mode of operation of the heating apparatus 110, as will now be described.
Figs. 4 is a flow chart illustrating the operation of the heating apparatus 110 in measuring mode. Figures Sand 6 show the configuration of the heating apparatus 110 in measuring mode. The controller 120 switches the heating apparatus 110 to measuring mode (step 405) by switching the mode switching device 323 to selectively connect the current source 305.
The measuring mode has two separate measurement periods, with the controller 120 initiating one measurement period followed by the other: * In a first measurement period, the heating apparatus 110 is arranged as illustrated in Fig. 5. At step 410, the controller 120 closes the heating element switching device 324 to electrically couple the heating element 115 to the current source 305 in order to apply a test current from the current source 305 to the heating element 115. At the same time, the controller 120 opens the reference resistor switching device 325 to electrically decouple the reference resistor 310 from the current source 305. At step 425, the voltage sensor 315 measures the voltage drop across the heating element 115 caused by the test current.
* In the second measurement period, the heating apparatus is arranged as illustrated in Fig. 6. At step 415, the controller 120 opens the heating element switching device 324 to electrically decouple the heating element 115 from the current source 305. At the same time, the controller 120 closes the reference resistor switching device 325 to electrically couple the reference resistor 310 to the current source 305 in order to apply the test current from the current source 305 to the reference resistor 310. At step 430, the voltage sensor 315 measures the voltage drop across the reference resistor 310.
The current source 305 applies substantially the same test current to the reference resistor 310 and the heating element 115. The exact value of the test current need not be known because the known resistance value of the reference resistor 310 provides a reference for the resistance of the heating element to be determined based on the measured voltage drops.
At step 435, the controller 120 determines the resistance of the heating element 115 based on the voltage drop across the heating element 115, the voltage drop across the reference resistor 310 and the known resistance of the reference resistor 310. At step 440, the controller determines the temperature of the heating element 115 by comparing the determined resistance of the heating element 115 with a resistance versus temperature profile of the heating element 115.
The resistance of the heating element 115 based on the voltage drop across the heating element 115, the voltage drop across the reference resistor 310 and the known resistance of the reference resistor 310 may be determined using the equation:
V
Re = RT( elvd where: Re is the resistance of the heating element 115, Rr is the predetermined resistance of the reference resistor 310, ve is the measured voltage drop across the heating element 115 as measured during the first measurement period of the measuring mode and V, is the voltage drop across the reference resistor 310 as measured during the second measurement period of the measuring mode.
The resistance of the heating element 115 may be determined using hardware (for example, an amplifier) or software running on a processor.
Fig. 7 is a block diagram illustrating the configuration of the heating apparatus 110 in the heating mode. The two-way switch of the mode switching device 323 connects to the battery 105 via the heating circuit 106, disconnecting the current source 305, and the heating element switching device 234 is closed to electrically couple the battery 105 to heating element 115 to electrically heat the heating element 115. In this mode, the controller 120 opens the reference resistor switching device 325 to electrically decouple the reference resistor 310 from the battery 105 so that energy does not dissipate through the reference resistor 310.
The heating element switching device 324 and the reference resistor switching device 325 may be field effect transistors or similar fast operating switching devices. Using fast operating switching devices would significantly reduce the amount of time the heating apparatus 110 operates in measuring mode, reducing the potential loss in heating of the heating element 115 when the heating apparatus 110 is not in heating mode.
Fig. 8 shows a block diagram of a heating apparatus 110 with an optional current sensor 805. The current sensor 805 measures the current flowing through the heating element 115. The controller 120 may use the measured current to detect short-circuits, or to monitor the operation of other components within the heating apparatus, such as monitoring operation of mode switching device 323. For example, if the heating apparatus 110 is operating in measuring mode, a small test current would be expected through the heating element 115 and detecting a large current instead may indicate that the mode switching device 323 is not operating correctly. Therefore, if the controller 120 receives a measured current through the heating element 115 that is above a current threshold, the controller 120 may prevent the heating apparatus 110 from operating in heating mode.
The heating apparatus 110 may include one or more supplementary sensors, such as a liquid level sensor to measure the water level in the water vessel 113, or a sensor to detect whether a lid of the water vessel 113 is open or closed. The controller 120 may use one or more measurements from the supplementary sensors to control whether the heating apparatus 110 may enter the heating mode. For example, the controller 120 may prevent electrical heating of the heating element 115 where the measurements suggest conditions may be unsafe for operating the heating element 115 (such as when there is insufficient water in the water vessel 113 or when a lid of the water vessel 113 is open).
Although the electricity supply has been described as being a battery 105, the electricity supply could be any other electrical power source. The invention is particularly suited to applications where the voltage of the power source is not known or where the voltage may change (such as an unregulated power source, like a battery, solar panel or a capacitor bank), because the method of determining the resistance based on the voltage drop across the heating element and the voltage drop across a known resistor eliminates the need for any prior knowledge of the voltage.
Although the examples show the heating apparatus 110 being used in a vehicle 100, the heating apparatus 110 is not limited to use in a vehicle and could be used anywhere, in any domestic, commercial and industrial setting.
The heating apparatus 110 has been described as having a single voltage sensor 315, with the measuring mode having two measuring periods to allow the single voltage sensor 315 to measure the voltage drop across the heating element 115 and the reference resistor 310 sequentially. However, the heating apparatus 110 could have two voltage sensors, one for measuring the voltage drop across the heating element 115 and one for measuring the voltage drop across the reference resistor 310 in a single measurement period.
The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims (25)

  1. Claims 1. A heating apparatus comprising a heating element and a controller, wherein the controller is configured to switch the heating apparatus between: a heating mode in which the heating element is electrically coupled to a heating circuit configured to provide an electricity supply to electrically heat the heating element, and a measuring mode in which the heating element is electrically decoupled from the heating circuit and a temperature of the heating element is determined based on a resistance of the heating element while electrically decoupled from the heating circuit.
  2. 2. The heating apparatus of claim 1, wherein the measuring mode further comprises electrically coupling the heating element to a measuring circuit, and the heating mode further comprises electrically decoupling the heating element from the measuring circuit.
  3. 3. The heating apparatus of claim 2, wherein the measuring circuit comprises a current source, a voltage sensor, and a reference resistor having a pre-determined resistance, and wherein during the measuring mode: the current source is configured to apply a test current to the heating element and the voltage sensor is configured to measure a voltage drop across the heating element; the current source is configured to apply the test current to the reference resistor and the voltage sensor is configured to measure a voltage drop across the reference resistor; and the controller is configured to determine the resistance of the heating element based on the voltage drop across the heating element, the voltage drop across the reference resistor and the pre-determined resistance of the reference resistor.
  4. 4. The heating apparatus of claim 3, wherein the current source is configured to provide less power than the electricity supply.
  5. 5. The heating apparatus of either of claims 3 or 4, wherein the voltage sensor is configured to measure the voltage drop across the heating element during a first measurement period and the voltage drop across the reference resistor during a second measurement period.
  6. 6. The heating apparatus of any of claims 3 to 5, further comprising a heating element switch in series with the heating element and a reference resistor switch in series with the reference resistor.
  7. 7. The heating apparatus of claim 6 wherein, during the heating mode, the controller is configured to close the heating element switch to electrically couple the heating element to the heating circuit and open the reference resistor switch to electrically decouple the reference resistor from the heating circuit.
  8. 8. The heating apparatus of either of claims 6 or 7, wherein the measuring mode comprises a first measurement period and a second measurement period, wherein: during the first measurement period, the controller is configured to close the heating element switch and open the reference resistor switch to electrically couple the heating element to the current source and the voltage sensor, and electrically decouple the reference resistor from the current source and the voltage sensor, in order to measure the voltage drop solely across the heating element; and during the second measurement period, the controller is configured to open the heating element switch and close the reference resistor switch to electrically decouple the heating element from the current source and the voltage sensor, and electrically couple the reference resistor to the current source and the voltage sensor, in order to measure the voltage drop solely across the reference resistor.
  9. 9. The heating apparatus of any preceding claim, wherein the controller is configured to compare the temperature of the heating element with a threshold temperature, and wherein the controller is further configured to prevent electrical heating of the heating element when the temperature of the heating element is above the threshold temperature.
  10. 10. The heating apparatus of any preceding claim, wherein the heating apparatus further comprises a current sensor configured to measure a current through the heating element, wherein the controller is configured to compare the current through the heating element with a threshold current, and wherein the controller is further configured to prevent electrical heating of the heating element when the current through the heating element is above the threshold current.
  11. 11. The heating apparatus of any preceding claim, wherein the electricity supply is unregulated.
  12. 12. The heating apparatus of any preceding claim, wherein the electricity supply is from a battery associated with the vehicle.
  13. 13. A vehicle comprising a battery and a heating apparatus according to any of claims 1-11, wherein the electricity supply comprises the battery.
  14. 14. A method of determining a temperature of a heating element in a heating apparatus, the method comprises switching the heating apparatus between: a heating mode comprising electrically coupling a heating element to a heating circuit that is configured to provide an electricity supply to electrically heat the heating element, and a measuring mode comprising electrically decoupling the heating element from the heating circuit, and determining a temperature of the heating element based on a resistance of the heating element while electrically decoupled from the heating circuit.
  15. 15. The method of claim 14, wherein the measuring mode further comprises electrically coupling the heating element to a measuring circuit, and the heating mode further comprises electrically decoupling the heating element from the measuring circuit.
  16. 16. The method of claim 15, wherein during the measuring mode, the method comprises: applying a test current from a current source to the heating element and measuring, using a voltage sensor, a voltage drop across the heating element; applying the test current from the current source to a reference resistor having a pre-determined resistance and measuring, using the voltage sensor, a voltage drop across the reference resistor; determining a resistance of the heating element based on the voltage drop across the heating element, the voltage drop across the reference resistor and the predetermined resistance of the reference resistor.
  17. 17. The method of claim 16, wherein the current source provides less power than the electricity supply.
  18. 18. The method of either of claims 16 or 17, further comprising measuring, using the voltage sensor, the voltage drop across the heating element during a first measurement period and the voltage drop across the reference resistor during a second measurement period.
  19. 19. The method of any of claims 16-18, further comprising providing a heating element switch in series with the heating element and a reference resistor switch in series with the reference resistor.
  20. 20. The method of claim 19 wherein, during the heating mode, the method comprises: closing the heating element switch to electrically couple the heating element to the heating circuit, and opening the reference resistor switch to electrically decouple the reference resistor from the heating circuit.
  21. 21. The method of either of claims 19 or 20, wherein the measuring mode comprises a first measurement period and a second measurement period, wherein: during the first measurement period, the method comprises closing the heating element switch and opening the reference resistor switch to electrically couple the heating element to the current source and the voltage sensor, and electrically decouple the reference resistor from the current source and the voltage sensor, in order to measure the voltage drop solely across the heating element; and during the second measurement period, the method comprises opening the heating element switch and closing the reference resistor switch to electrically decouple the heating element from the current source and the voltage sensor, and electrically couple the reference resistor to the current source and the voltage sensor, in order to measure the voltage drop solely across the reference resistor.
  22. 22. The method of any of claims 14 to 21, wherein the method further comprises comparing the temperature of the heating element with a threshold temperature, and preventing electrical heating of the heating element when the temperature of the heating element is above the threshold temperature.
  23. 23. The method of any of claims 14 to 22, wherein the method further comprises measuring a current through the heating element using a current sensor, comparing the current through the heating element with a threshold current, and preventing electrical heating of the heating element when the current through the heating element is above the threshold current.
  24. 24. The method of any of claims 14 to 23, wherein the electricity supply is unregulated.
  25. 25. The method of any of claims 14 to 24, wherein the electricity supply is from a battery associated with the vehicle.
GB2102630.7A 2021-02-24 2021-02-24 Heating apparatus Active GB2595334B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2102630.7A GB2595334B (en) 2021-02-24 2021-02-24 Heating apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2102630.7A GB2595334B (en) 2021-02-24 2021-02-24 Heating apparatus

Publications (3)

Publication Number Publication Date
GB202102630D0 GB202102630D0 (en) 2021-04-07
GB2595334A true GB2595334A (en) 2021-11-24
GB2595334B GB2595334B (en) 2022-06-08

Family

ID=75339309

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2102630.7A Active GB2595334B (en) 2021-02-24 2021-02-24 Heating apparatus

Country Status (1)

Country Link
GB (1) GB2595334B (en)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4086466A (en) * 1976-04-30 1978-04-25 Scharlack Ronald S Automatic heater controller
US4506146A (en) * 1981-08-21 1985-03-19 Reynolds Metals Company Wire temperature controller
US4549073A (en) * 1981-11-06 1985-10-22 Oximetrix, Inc. Current controller for resistive heating element
US5120936A (en) * 1990-08-22 1992-06-09 Industrial Technology Research Institute Multiplex heating system with temperature control
US5408577A (en) * 1992-03-16 1995-04-18 Sonne Medical Method and heater apparatus with protective fuse for medical applications
EP0745919A1 (en) * 1995-05-30 1996-12-04 Koch, Volker Method for regulating the temperature of a heating element
WO2007076688A1 (en) * 2005-12-31 2007-07-12 Capitalbio Corporation Methods and devices for controlling temperature without temperature sensor
US20180106686A1 (en) * 2016-10-13 2018-04-19 Infineon Technologies Austria Ag Temperature Sensing and Control of Resistive Heating Elements

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4086466A (en) * 1976-04-30 1978-04-25 Scharlack Ronald S Automatic heater controller
US4506146A (en) * 1981-08-21 1985-03-19 Reynolds Metals Company Wire temperature controller
US4549073A (en) * 1981-11-06 1985-10-22 Oximetrix, Inc. Current controller for resistive heating element
US5120936A (en) * 1990-08-22 1992-06-09 Industrial Technology Research Institute Multiplex heating system with temperature control
US5408577A (en) * 1992-03-16 1995-04-18 Sonne Medical Method and heater apparatus with protective fuse for medical applications
EP0745919A1 (en) * 1995-05-30 1996-12-04 Koch, Volker Method for regulating the temperature of a heating element
WO2007076688A1 (en) * 2005-12-31 2007-07-12 Capitalbio Corporation Methods and devices for controlling temperature without temperature sensor
US20180106686A1 (en) * 2016-10-13 2018-04-19 Infineon Technologies Austria Ag Temperature Sensing and Control of Resistive Heating Elements

Also Published As

Publication number Publication date
GB2595334B (en) 2022-06-08
GB202102630D0 (en) 2021-04-07

Similar Documents

Publication Publication Date Title
US7668445B2 (en) Apparatus and method for detecting condition of a heating element
US7103272B2 (en) Water heater and method of operating the same
US9006616B2 (en) Portable spa monitoring and control circuitry
US7117825B2 (en) System and method for preventing overheating of water within a water heater tank
US20070133965A1 (en) Control and method for operating an electric water heater
CN105493396B (en) Control device of electric motor
US11366075B2 (en) Method for determining an amount of deposition of scale on a heating element and household appliance comprising a heating element
KR20080069613A (en) Control device for an engine-independent heater, heating system, and method for controlling an engine-independent heater
GB2595334A (en) Heating apparatus
US20200309387A1 (en) Hot water supply device
CN114585864A (en) Water heater and method for controlling water heater
GB2589824A (en) Boiler Control System and Method
JP2022506379A (en) How to detect overheating of heating equipment and the corresponding control unit
CN110221636A (en) A kind of hot satellite line intelligent temperature controller and its application method
EP3667184A1 (en) Boiler control system and method
JPH11118619A (en) Thermistor failure detecting method
JPH11118620A (en) Thermistor failure detecting method
CN116565802A (en) PTC control method and device based on power tube protection
JPH05115368A (en) Electric kettle
JP2013164289A (en) Control device and control method for temperature measuring unit
US20190201282A1 (en) Spa control with novel heater management system
CN114251829A (en) Instantaneous heating device, control method and control device thereof, water treatment device and medium
JPH0411776B2 (en)
KR100186709B1 (en) Control of flame perception sensor using thermal conductor of electronic gas range
JPH05277030A (en) Electric water boiler