AU6545599A - Control apparatus for a solid fuel heater - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT 4 a.

a a S. a a S Applicant(s): WILHELMUS BERNARDUS MARTINUS KEEMAN InVention Title: CONTROL APPARATUS FOR A SOLID FUEL HEATER The following statement is a full description of this invention, including the best method of performing it known to me/us: CONTROL APPARATUS FOR A SOLID FUEL HEATER TECHNICAL FIELD This invention relates to improvements in control apparatus and devices' used in conjunction with solid fuel heaters.

Specifically the present invention may be adapted to automate and manage the operation of such heaters. However, those skilled in the art should appreciate that other applications for the present invention are envisaged. Reference throughout the specification will also be made to the present invention as being used in conjunction with solid fuel heaters. A solid fuel heater may be defined as any apparatus or device which is adapted to allow the combustion of a solid or substantially solid fuel to release heat into a region, thereby warming same.

BACKGROUND ART Heaters which combust or burn solid fuels have become relatively popular over recent years. Due to improvements to the design and operation of such heaters •15 they have become relatively efficient and popular with users who have an abundant or ready supply of solid fuel.

However, because of the nature of the fuels they combust such heaters have a number of problems associated with their use and operation.

Existing solid fuel heaters do not allow for the accurate control of temperature in a region or room. Usually such devices employ a manually operated sliding air inlet valve, the position of which will determine how much air enters the heater, and hence how quickly the fuel inside the heater burns. This method of controlling temperature depends on the temperature perceived by an occupant of the room. If any person using such a heater begins to feel cold, it takes a significantly long James Wells ref: 25104 Is.

period of time for such solid fuel heaters to raise temperature in a room.

Alternatively if a room is overheated, it takes a long period of time for an occupant to detect that the heater is combusting fuel too rapidly for their own comfort. Using such simple manually operated inlet valves, it is extremely difficult to keep the temperature of a room constant. Using an existing device the operator would have to almost continually adjust the position of such an inlet valve based on their own perception of room temperature.

In addition, with existing solid fuel heaters, fuel levels within same need to be monitored by the user. As the heater combusts fuel, its energy output will be reduced over time until the fire inside the heater eventually goes out. This is an inconvenience for some users who would prefer not to have to frequently monitor fuel levels.

Solid fuel heaters also suffer from what can be described as 'flue-blockages'. The "flue may be defined as any exit point or outlet from a heater which allows exhaust 15 gases to exit from same. Flue blockages are caused when wet or green wood is added to an existing fire. This relatively low quality wood drops the average S"temperature of air within the heater due to its high moisture content. The cool air makes its way up into the flue, where it may form a plug or a block to any subsequently warmer air generated in the heater.

This is a problem with existing fuel heaters, as most operators will not even realise that a flue blockage has occurred. If the operator finds that their fire is slowly dying due to a flue blockage, they have to manually open up the heater's air inlet valve to increase the heater's rate of combustion. This will normally create a large amount of hot air, thereby forcing the plug or blockage of cool air out of the flue. However, it is also difficult for some people to know when a flue blockage has been cleared.

James Wells reft: 25104 ,4 7 An improved control apparatus for a solid fuel heater, which addresses any or all of the above problems, would be of great advantage over the prior art.

Specifically a control apparatus for a solid fuel heater which could indicate when the fuel levels in such a heater was low, which could maintain a relatively constant temperature in a room and which could automatically clear flue blockages would be a great advantage over the prior art.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description that is given by way of example only.

DISCLOSURE OF INVENTION According to one aspect of the present invention there is provided a control S.:i apparatus for a solid fuel heater, said control apparatus including, at least one temperature sensor, and at least one inlet valve adapted to control the amount of air admitted to the solid fuel heater, and a control element adapted to operate the inlet valve or valves dependent on a temperature signal obtained from the temperature sensor or sensors.

i According to another aspect of the present invention there is provided a control apparatus substantially as described above wherein a temperature sensor is located remote from the heater.

3 James Wells ref: 25104

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According to yet another aspect of the present invention there is provided a control apparatus substantially as described above, wherein the apparatus includes an indicator, said indicator being operable by the control element.

According to a further aspect of the present invention there is provided a method of operating a solid fuel heater using a control apparatus substantially as described above, said method of operation characterised by the steps of; 1 sensing a temperature using a temperature sensor, and 2 providing a temperature signal to the control element, and 3 operating an inlet valve using the control element, wherein operation of the inlet valve is dependent on the temperature signal .".received by the control element.

According to yet another aspect of the present invention there is provided a method of operating a solid fuel heater substantially as described above, further #•oo characterised by the additional subsequent step of; 15 4 activating an indicator using the control element, S. wherein the control element activates the indicator dependent on the temperature signal it receives and the position of the inlet valve or valves.

According to another aspect of the present invention there is provided a method of operating a solid fuel heater using a control apparatus, characterised by the steps 'of: 1 sensing a change in temperature in a particular region, and 2 opening an inlet valve using control element, and James Wells ref: 25104 3 sensing the temperature again within said region, and 4 determining whether the temperature sensed is within an acceptable range of values, and activating an indicator if said sensed temperature value is outside said acceptable range of temperature values.

According to yet another aspect of the present invention there is provided a method of operating solid fuel heater, characterised by the steps of: 1 sensing a drop in temperature in a particular region of the solid fuel heater, and 2 opening an inlet valve using control element, and 3 sensing the temperature again within said region, and 4 determining whether the temperature sensed is within an acceptable range .of values, and 5 opening said inlet valve further if the temperature sensed is below a range of acceptable values for said temperature, and S"6 sensing said temperature again, and -oooo 7 activating an indicator if the sensed temperature is below an acceptable S. range of values for said temperature.

A solid fuel heater may be defined as any apparatus or device that is adapted to burn or combust substantially solid fuels. For example, solid fuel heaters may be adapted to burn wooden logs or wood type materials such as saw dust or James Wells ref: 25104 compressed wood fibres, paper, coal, peat or any other substantially solid combustible material.

In a preferred embodiment a solid fuel heater which the present invention may be used with may be configured into a substantially cube shaped apparatus with a flue connected to its top end. Such a heater may have a central combustion chamber within the main block shaped body that is used to contain and combust the heaters fuel. This configuration of solid fuel heater is relatively common, efficient and popular with its users.

A control apparatus configured in accordance with the present invention may be any arrangement or configuration of elements, which is adapted to control the operation of a solid fuel heater. Such a device may be constructed from any configuration of electrical or mechanical devices that preferably allow for the automated or automatic control of a solid fuel heater.

In a preferred embodiment a solid fuel heater may include at least one inlet valve adapted to control the flow or amount of air allowed to enter the heater. Those skilled in the art will appreciate that the rate of combustion within the heater will a. ae be controlled by the amount of fuel within the heater and also the amount of air that can flow into the heater.

•-In existing solid fuel heaters, control of the heater's output is usually achieved by a single manually operated slide valve. The operator may grasp a handle attached to the slide valve and manually push a valve element to open or close the valve.

However, as discussed above it is difficult for an operator to select the correct valve position for the amount of fuel within the heater to ensure that a relatively constant temperature is maintained within a room.

James Wells ref 25104 In a preferred embodiment the present invention may be adapted for use with a solid fuel heater with a single air inlet valve. In a further preferred embodiment the single air inlet valve may be a slide type valve which is normally manually operated. This configuration in the invention allows it to be retrofitted onto existing heaters and also to be used in existing designs without requiring significant modifications to the heater. However, those skilled in the art should appreciate that the present invention may be adapted to operate and control any number and configuration of air inlet valves, and reference to the above only throughout the specification should in no way be seen as limiting.

In a preferred embodiment the present invention may employ at least one temperature sensor. Such a temperature sensor may be adapted to provide a temperature signal that indicates the temperature of a particular area or region.

A temperature signal from a temperature sensor may be transmitted to a control •.element to provide information with regard to the temperature within a particular region of the heater or of the temperature of a region near the heater. This information can then be used by the control element to control the operation of a heater.

In a preferred embodiment the invention may also include an external temperature :sensor located outside of and remote from the solid fuel heater. This sensor may provide information with regard to the temperature produced in a room by the solid fuel heater.

In such an embodiment the information provided by the sensor may be used by the control element to control the operation of the solid fuel heater. This external sensor preferably located remote from the exterior of the heater's combustion chamber to provide information with regard to the temperature within a room and 7 James Wells ref: 25104 (a i hence whether the output of the heater needs to be adjusted to suit the comfort levels of the room's occupants.

Preferably such an external temperature sensor may be located as far away as possible from the heater to ensure that the temperature sensor will be able to take a temperature reading which is indicative of the actual room temperature, not of the air near to the heater. The exact placement and location of such an external temperature sensor will be dictated by the particular configuration of a room or region in which the heater is located, and also whether the present invention is being installed as an integral part of a new heater or alternatively is being retrofitted as an after market product for an existing heater.

For example, in the case where the invention is provided as an integral part of a new heater, a relatively long cabling system may be provided to place the external temperature sensor at a location as far away as possible from the heater.

Alternatively where the invention is provided as an after market product, it may be :15 difficult to site the external temperature sensor remote from the heater and the sensor may be located on the external casing of the heater. In such an embodiment the temperature sensor may also include insulative elements positioned between itself and the body of the heater.

In a preferred embodiment where the invention includes an external temperature 20 sensor, this sensor may provide a temperature reading from air currents in the vicinity of the sensor. Such a sensor can provide accurate and representative Ssample of the average air temperature within a particular room or region.

In some alternative embodiments a temperature sensor used may be located within the interior of the solid fuel heater. For example, it some embodiments a temperature sensor may be located within the heater's flue. This configuration of a temperature sensor or sensors allows same to provide a direct reading of how 8 James Wells ref: 25104 much heat is actually being generated by the heater, as opposed to how much heat is transmitted to its surroundings.

In some alternative embodiments the present invention may employ two separate temperature sensors located in separate areas of a solid fuel heater. The first temperature sensor may be located remote from the solid fuel heater's combustion chamber to provide an indication as to the ambient temperature of a room to be heated. A second temperature sensor may be located within the heater's flue to sense the temperature of gases within the flue. This configuration of temperature sensors provides a control element information with regard to temperatures in two specific separate regions.

Reference throughout the specification will now however be made to the present invention employ temperature sensor only located remote from the heater's combustion chamber. However, it should be appreciated by those skilled in the art that other configurations of the present invention are envisaged and reference 15 to the above only throughout the specification should in no way be seen as limiting. For example, a pair of temperature sensors may be used in some S.embodiments, as discussed above.

The control element may be any arrangement or configuration of components, .which is adapted to receive temperature signals from a sensor or sensors and to .ooo.i 20 actuate or operate the air inlet valve of the heater.

In a preferred embodiment a control element configured in accordance with the ,present invention may include a programmable logic device such as a programmable logic controller or a microprocessor. Such devices may be adapted to receive an electrical temperature signal from a sensor, to process this signal and to issue control signals to actuating elements which may move or manually operate a heaters air inlet valve. Preferably the control element also includes James Wells ref: 25104 actuation devices such as, for example, a solenoid or stepper motor which may be used to adjust or operate the heaters air inlet valve.

In a preferred embodiment the actuation device associated with the control element may be an electric motor. An electric motor may be controlled easily by electrical signals from the control element to in turn open or close an air inlet valve for the heater. In such an embodiment the electric motor used may preferably push or pull on a rigid cable extending to an air inlet valve to push or pull open or closed the heater's air inlet valve.

In a further preferred embodiment a programmable logic device used as a control element may include a user interface to allow a user to program particular operational requirements into the control element and also to receive information from the control element as to the current state and configuration of the heater.

e* For example, in one embodiment, a user may program in an acceptable temperature range required for a room and may also receive information from the interface as to the temperature within particular regions or areas of the heater.

This configuration of a control element may be cheaply and easily produced using existing technology to providing rapid, automated and accurate control of the operation of a solid fuel heater.

In a preferred embodiment a control element may also be adapted to receive 20 control signals from a user operable remote control device. Such devices are well 9* S" known in the art and may be configured to exchange signals with the programmable logic device to control the operation of same, and hence the operation of a solid fuel heater. In such an embodiment the remote control used may include a display which displays the temperature sensed by the control apparatus' temperature sensor or sensors and may also transmit control instructions from the operator to the control element.

James Wells ref: 25104

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Reference throughout the specification shall now be made to the control element being configured to include a programmable logic device and an electric motor adapted to operate an air inlet valve the heater. However, it should be appreciated by those skilled in the art that any number and type of configurations of alternative devices may be used in conjunction with the present invention to provide a control element. For example in one alternative embodiment analogue electrical circuitry may be first be calibrated and used to receive analogue temperature signals which can then be amplified and used to power or operate a solenoid linked to an air inlet valve.

In a further preferred embodiment the control element may also include a valve position sensor which is adapted to provide valve position information to the control element. For example in one embodiment such a valve position sensor may include or consist of a number of limit switches which will be triggered when ::the inlet valve is placed in a particular position or configuration. Alternatively, a oo* 15 valve position sensor may be implemented using a software algorithm *'0"0programmed into the control element's logic device. Such an algorithm may remember or record each movement of the inlet valve by the control element, and hence be able to determine the particular position of the valve at a particular time.

In a preferred embodiment the control element may include a user operable override control. Such a control may be provided so that, once activated by the user, it disable the operation of the control apparatus and prevent it from opening or closing a heater's air inlet valve. The user may operate such a control so that they can change and control for themselves the position of the heater's air inlet valve.

In a preferred embodiment the control apparatus may include at least one indicator. An indicator may be controlled or operated by the control element to 11 James Wells ref: 25104 provide a warning or alerting indication to a solid fuel heater's users. In a further preferred embodiment such an indicator may be adapted to indicate that a heater is low on fuel. The control element may operate the indicator dependent on information it receives regarding the temperatures within particular regions of the heater, and the position of the inlet valve.

The present invention as described above may be adapted to solve a number of problems associated with existing types of solid fuel heaters.

The present invention may be adapted to regulate the rate of combustion within the heater so that the heater provides a constant temperature within a particular region or room. This may be achieved by the control element receiving information from a temperature sensor regarding temperatures within the room.

As the temperatures rises or falls, as fuel is combusted, the control element may operate the air inlet valve to keep the temperature of the room heated at a relatively constant level.

In one embodiment the present invention may also be adapted to automatically sense the existence of and also to clear flue blockages. In such an embodiment, :where the invention includes a temperature sensor within the heater's flue, the sensor may indicate that the flue temperature has dropped and that there is a blockage of cold air within the flue. Once the control element receives this information it may open up the heaters air inlet valve, increasing the rate of •combustion within the heater and thereby forcing the "plug" of cold air out of the flue with a large amount of hot air from the combustion chamber. Once the flue temperature begins to rise again the control element may close off the inlet valve ooeoo to keep the amount of heat generated by the heater relatively constant.

S 25 The present invention may also be adapted to provide an indication as to the levels or amount of fuel contained within the heater. If, as in the above embodiment, the James Wells ref: 25104 invention includes a temperature sensor within the heater flue and the sensor indicates that there has been a temperature drop, the control apparatus may assume that there is a flue blockage within the flue and open up the heater's air inlet valve.

If this action does not result in the flue temperature rising after a set period of time, the control element may activate an indicator to alert the users of the heater that the heater is low on fuel. If opening up the air inlet valve has little effect on the temperature of the flue, it may be assumed that there is little or no fuel remaining within the heater to provide enough heat to either clear a flue blockage or heat the flue significantly. At this stage the control element can activate the indicator to warn that the heater is running low on fuel.

In a preferred embodiment where the present invention includes only a single external temperature sensor, the invention may again be configured to provide an indication or warning of low fuel levels within the heater. If the external temperature sensor detects a drop in the temperature of a room or region the control apparatus can then open the air inlet valve to boost the rate of combustion within the heater. After a short period of time the temperature within the room can then be sampled again to determine whether the temperature sensed is within o an acceptable range of values. If the temperature sensed is outside of this .acceptable range of values, the control apparatus can then activate an indicator to 20 warn that the heater is running low on fuel.

The present invention may be provided as either an after market product for existing heaters or as an integral part of a new heater. As an after market product the present invention may be provided with a series of brackets or connectors i which are adapted to allow the invention to connect to and control an existing heater. For example, in one embodiment such a bracketing system may consist of or include a series of flanges or tabs extending out from the edges of a housing for James Wells ref: 25104 the control element where these flanges or tabs may be easily screwed, bolted or riveted onto the body of the heater.

The above features may provide the present invention with significant potential advantages over the existing prior art.

With the present invention the operation of a solid fuel heater may be automatically controlled and monitored. There is no need for the user to continually adjust an air inlet valve to provide the optimum or best operation of the heater. The present invention may also be adapted to provide a convenient warning signal or indication if the heater is running low on fuel.

The present invention may be adapted to solve problems specific to solid fuel heaters. As the supply of fuel to the heater cannot be accurately gauged or controlled (as is in the case with most types of gas burning heaters) special care and attention needs to be taken with the operation of a solid fuel heater. Someone skilled in the art of gas fire heaters would not immediately be aware of the problems associated with solid fuel heaters.

BRIEF DESCRIPTION OF DRAWINGS "":'"Further aspects of the present invention will become apparent from the ensuing description that is given by way of example only and with reference to the accompanying drawings in which: 20 Figure 1 shows a sketch of a control apparatus as configured in one embodiment associated with existing type of solid fuel heater; and "Figure 2 shows a flow diagram of the steps taken by the control element as configured in one embodiment to automatically operate an existing "solid fuel heater.

James Wells ref: 25104 ii Figure 3 shows an arrangement of a control apparatus configured in accordance with one embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION Figure 1 shows a sketch of a solid fuel heater 1, which has the control apparatus of the present invention as configured in one embodiment installed onto same.

The solid fuel heater 1 includes a main central combustion chamber 2 and a flue 3.

Fuel may be inserted into combustion chamber 2, burnt within the chamber, and any waste exhaust gases may be removed from the heater 1 via the flue 3. The heater 1 also includes a single air inlet valve assembly 4 which is adapted to regulate and control the amount of air admitted to the combustion chamber, and hence the rate of combustion within same.

Figure 1 also shows the control apparatus of the present invention as configured in one embodiment and shown generally by reference 5. In this embodiment the control apparatus includes a flue temperature sensor 6 located within the heaters flue, and an external temperature sensor 7 located adjacent to the combustion chamber of the heater. These two sensors may provide information with regard to the temperature of these areas of the heater to a control element 8. The control eee..element 8 is linked to an actuating device, which in this embodiment, is a solenoid 9. The solenoid 9 is adapted to manually operate the heater's air inlet valve 4 S 20 upon receipt of control signals sent from the control element 8.

When in use each of the sensors 6,7 provides a temperature signal to the control S'element 8. Depending on the particular temperatures sensed the control element may operate the actuator and hence the air inlet valve 4 to regulate the operation of the heater. The control element 8 may frequently monitor the temperatures of 25 the combustion chamber and flue and control the rate of combustion with the James Wellsref: 2510 4 heater to ensure that a relatively constant temperature is maintained within a room containing the heater 1.

As discussed above the control element may also be adapted to clear flue blockages if these are sensed by the flue temperature sensors 6, and also to activate or operate an indicator 10 if the control element senses that the heater 1 is low on fuel.

Also as discussed above the control element 8 may. also be adapted to receive control signals from a user operable remote control device. Such a remote control device may also display to its operator information sourced from the control element 8 Figure 2 shows a flow chart of steps taken by the control element 1 as configured in one embodiment of the present invention.

Firstly the control element reads the temperature or temperatures of particular regions of the heater. If the temperatures read are above a set maximum the control element will close the heaters inlet valve further, wait a set period of time and then read the temperature again to determine if this has had the desired effect of dropping the heaters temperature.

If the control element senses that the heaters temperature is below a set minimum it will open the inlet valve further, wait a set period of time, re-read the temperature and check again to see if it is reached or exceeded a pre-determined minimum, if the correct temperature has still notbeen reached the control S."'element will again open the inlet valve further, wait a set period of time and then ee*oo re-read the temperature again. If this still does not have the desired effect the control element will activate a low fuel warning indicator to alert the users of the *°o James Wells ref: 25104 heater that the heater is low on fuel. The control element will then wait two set periods of time before re-reading the temperature of the heater again.

Figure 3 shows a control apparatus 11 configured in accordance with one embodiment of the present invention.

The control apparatus 11 is adapted to interface with an air inlet slide valve 12 for a solid fuel heater. The valve 12 may be adapted to control the amount of air entering into the heater and hence at least in part the combustion rate of fuel within the heater.

The actuator includes a main body portion 13 which houses a microprocessor and a small electrical motor (not shown). The electric motor may be controlled by the microprocessor to push or pull on a steel wire cable 14 to in turn exert a pushing or pulling force on the sliding mechanism of the slide valve 12. The movement of the cable 14 will open or close further the slide valve 12.

The control apparatus 11 also includes cable adjustment element 16 which is adapted to allow for modification of the connection of the cable 14 to the slide element of a valve 12. This feature of the invention allows the control apparatus to be used to control numerous different types and arrangements of slide valves used in different makes and models of solid fuel heaters.

The control apparatus 11 also includes a manually operated override control 17.

20 The override control button 17 shown in this embodiment may be depressed by the invention's user to override the actions of the control element 11 and hence .allow the user to open and close the slide valve 12 themselves without any interference from the control element 11.

interference from the control element 11.

James Wells ref: 25104 Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

For the purposes of this specification it will be clearly understood that the word "comprising" means "including but not limited to", and that the word "comprises" has a corresponding meaning.

*o So o James Wells ref: 25104