GB2099607A - Heating apparatus control system - Google Patents
Heating apparatus control system Download PDFInfo
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- GB2099607A GB2099607A GB8212604A GB8212604A GB2099607A GB 2099607 A GB2099607 A GB 2099607A GB 8212604 A GB8212604 A GB 8212604A GB 8212604 A GB8212604 A GB 8212604A GB 2099607 A GB2099607 A GB 2099607A
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- fire
- output
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- 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
- G05D23/1902—Control of temperature characterised by the use of electric means characterised by the use of a variable reference value
- G05D23/1905—Control of temperature characterised by the use of electric means characterised by the use of a variable reference value associated with tele control
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- Feeding And Controlling Fuel (AREA)
Abstract
Operation of a gas fire is controlled by digitally encoded signals of infra-red radiation which represent a selected mode of operation (e.g. a desired heat output rate or a fire temperature) and are generated, remotely from the fire, by actuation of a hand-held control device (20). The signals are received by an infra-red sensor and preamplifier unit (21) and then decoded at a receiver (24), the resulting analogue signals being utilized to initiate an appropriate control adjustment of the fire to attain the desired mode of operation. Additionally the fire has manual controls (22) to achieve the modes of operation. Ultrasonic or radio frequency radiation can also be used. <IMAGE>
Description
SPECIFICATiON
Improvements relating to the control of heating apparatus
This invention relates to heating apparatus and especially, although not exclusively, to a system for remotely controlling a domestic gas fire.
According to the invention there is provided a domestic heating apparatus including means for regulating an operational parameter of the apparatus, means for receiving transmitted coded signals indicative of a selected value of said parameter and generated at a location remote from the apparatus, and means responsive to received signals for controlling the regulation means so as to attain the selected value of said parameter.
According to another aspect of the invention there is provided a domestic heating apparatus including means for regulating the heat output rate, means for receiving transmitted coded signals indicative of a selected rate and generated at a location remote from the apparatus, the means responsive to received signals for controlling the regulation means so as to attain the selected heat output rate.
The heating apparatus may have means for manually regulating said operational parameter or said heat output rate.
The heating apparatus may be a gas fire and the regulation means may comprise a plurality of selectively operable valves for regulating the gas supply to the fire burner; the fire may have a first passageway (or network of passageways) for supplying gas (preferably from the regulation means) to the fire burner during remote operations and, separate from the first passageway, a second passageway (or network of passageways) for supplying gas (preferably from the regulation means) to the fire burner during manual control. The fire may have means for sensing a flame comprising means to control the supply of gas and the ignition of a flame.
The coded signals may be pulses of infra-red radiation generated by a portable transmitter and the receiving means may be an infra-red sensor.
In order that the invention may be more fully understood and carried into effect specific embodiments thereof are now described, by way of example, by reference to the accompanying drawings of which: Figure 1 shows the configuration of gas burners and their associated supply lines used in one example of the invention,
Figure 2 illustrates, in block schematic form, a control circuit for the arrangement of Figure 1,
Figures 3a to 3d illustrate detailed circuit diagrams of some of the components used in the circuit of Figure 2,
Figures 4 and 5 illustrate two alternative forms of control circuit.
Figure 6 illustrates the configuration of burners and their associated supply lines used in conjunction with the arrangement of Figure 5,
Figures 7a and 7b respectfully show a table representing a valve opening sequence and a logic control circuit useful in understanding the operation of the control circuit of Figure 5.
Figure 8 shows a modified form of the configuration of Figure 1,
Figure 9 shows the configuration of gas burners and their associated supply lines used in another embodiment of the invention,
Figure 10 shows, in block schematic form a control circuit for the arrangement of Figure 9 and
Figures 11 to 21 show detailed circuit diagrams of some of the components used in the circuit of
Figure 10.
In accordance with this example of the invention, operation of a gas fire is controlled by digitally encoded signals of infra-red radiation which represent a selected mode of operation e.g. a desired heat output rate or a thermostat temperature, and are generated, remotely from the fire by actuation of a hand-held control device. Signals of this kind, transmitted by the control device are received at the fire and then decoded, the resulting analogue or digital signals being utilised to initiate an appropriate control adjustment of the fire to attain the desired mode of operation.
The arrangement of burners used in one embodiment and their associated supply lines are shown diagramatically in Figure 1. Three burners are provided, namely a central burner 4 having a 3KW rating and two 1- KW burners, 5 and 6 which flank the central burner, and each burner has an associated radiant, 1, 2 and 3 respectively. An example of such a fire is that known as the Parkinson Cowan Prima
II. Gas is conveyed to the burners from an inlet port 10 along a conduit 1 7 via a main solenoid valve 1 2 and a Flame Failure Device (FFD) valve 11.Conduit 1 7 branches at B, the central burner 4 being supplied via branch B, containing four solenoid valves SV1 -SV4 arranged in series, and the two outer burners 5 and 6 being supplied via the branch B2 containing six solenoid valves SV5-SV1 0, similarly arranged in series. Except for SV5, each solenoid valve has an adjustable bypass restrictor R1-R10 (R5 is absent) and by selectively opening the valves SV1 -SV1 0 the rate of gas supply to the burners can be varied from a low value, when all the valves are shut and gas is passed to the central burner only, via restrictors R1-B4, to a maximum value, when all the valves are open and gas passes to each burner directly.By suitably adjusting the restrictors R1-R4 the flow rate attained when all the valves are shut can be optimised to obtain the minimum stable burning condition and by successively opening the solenoid valves SV1--SV10 the flow of gas to the burners can be progressively increased in stepwise fashion until the full 6KW output is attained.
When the fire is first turned on in readiness for ignition the main solenoid valve 12 and the solenoid valves SV1-SV4 are opened and the mains igniter 14 is energized so as to generate a series of sparks above the central burner. Initially the Flame Failure Device (FFD) valve 11 is only partially open, but bypasses gas to burner 4 at a rate which is sufficient to establish ignition. This causes heating of a flame sensitive phial 1 6, located above the central burner, which in turn causes valve 11 to open fully and so allows burner 4 to operate at its full 3KW rating. Subsequently the heat output rate can be increased or decreased by opening or closing valves SV1 -SV1 0 as appropriate. Furthermore, the fire can be extinguished completely by de-energising the main solenoid valve 12.
In accordance with this example of the invention, the solenoid valves and the igniter are actuated in response to the coded signals received by the fire, and electrical circuits provided for this purpose will be described below in detail. In this example, in addition to the above-mentioned remotely controlled arrangement, the supply of gas to the burners can also be controlled manually by operation of a tap, shown at 9 in Figure 1. In dependence on its position, the tap is capable of coupling the gas inlet 10 either solely to the central burner 4, via conduit 7, or to both the central and outer burners 4, 5 and 6, via conduit 8.In the illustrated "OFF" position the tap isolates the burners from the gas source, but rotation of the tap in the anticlockwise sense, from the "OFF" to the "HI" position causes an increasing flow of gas, initially to the central burner only and then to the outer burners also. An additional manually operated piezo electric igniter 1 3 is provided for use in these circumstances.
The electrical system used to control operation of the fire, in response to coded signals transmitted thereto, is illustrated in block schematic form in Figure 2, and elements of the system will be described below in greater detail by reference to Figures 3a to 3d.
Referring initially to Figure 2 however, the hand held control device used to transmit coded signals, indicative of a selected operational function of the fire is illustrated at 20. This device, supplied by R. S. Components Ltd.-RS 490 (308073)contains a dry battery and an integrated circuit which encodes signals, selected by depression of an appropriate control button to generate a distinctive five bit word. The encoded signals which comprise a series of electrical pulses, a short interval between pulses representing a binary "1", a longer interval representing a binary "0" and the longest interval representing a gap between words, are fed to two infra-red sources for conversion to infra-red pulses which are then transmitted to the control system of the fire.These signals are then detected by an infra red sensor protected by an infra red filter (Kodak No. 87). In this example of the invention, the heat output rate from the fire may be controlled directly by causing solenoid valves SV1 -SV1 0 to be progressively opened or closed until the desired rate is attained, and this is achieved by depression of the "Heat+" or "Heat" buttons of the control device. Alternatively the heat output rate may be controlled by means of a thermostat whose operating temperature can be set at a desired level by depression of a "Temperature+" or a "Temperature-" button.The control unit also has a "ON/STANDBY" button whereby in the "ON" condition the main solenoid valve 12, solenoid valves SV1-SV4 and the mains igniter 14 are turned on to ignite the central burner and in the "STANDBY" condition a small section only of the electric circuit is retained in an active state so as to be capable of responding when the ON mode is selected. In this example the above-described control functions are represented by the following binary words,
Heat+ 10110
Heat- 11110
Temperature+ 10100 Temperature- 1100 ON 11000
STANDBY 11101
In addition to the above-mentioned control facilities the system of this example also provides a visual bar display indicating the heat output rate, the thermostat operating temperature and the temperature of the room containing the fire.
Referring again to Figure 2, coded infra-red signals are received by an infra-red sensor and preamplifier unit 21 which amplifies the signals and filters out unwanted "noise". Signals indicative of a desired operational function of the fire may also be generated by actuation of a local push button transmitter 22 which is mounted to the fire for operation and generates signals of the same code as that of the hand held control device and has an identical layout. Coded signals, whether generated by the hand-held device 20 or the local transmitter 22 are then passed via a mixer 23 to a receiver, indicated generally at 24, which decodes the received signals at 25 and generates at the appropriate output location (i.e. at 26, for the ON/STANDBY mode, at 27-for regulation of the heat output, at 28for selection of the themostatically controlled mode, and at 29-for regulation of the thermostat operating temperature) an analogue or digital signal, suitable for initiating the required control response in accordance with the selected command. In this example the receiver 24, which comprises the components 25, 26, 27, 28 and 29, is an integrated circuit-RS 922 (308-089).If the fire "ON" condition is selected the output from 26 goes high (to 16V)) and is then used to energise a relay 30 via a driver circuit (not shown). The relay switches the mains voltage to the main solenoid valve 12, which is thereby opened, and to the mains relight igniter 14 and the transformer supplying the greater part of the circuits. It also starts a timer 31 which inhibits opening of the solenoid valve SV5 for about 30 seconds so as to give the Flame Failure Device valve 11 time to open fully. When the "STANDBY" condition is selected the output from 26 drops to zero.
When the heat output rate is to be adjusted directly an analogue output signal is generated at 27 which increases in 32 steps, from OV to 6.3V when the "Heat+" button is depressed or decreases in similar steps when the "Heat-" button is depressed, and this signal is passed via a switch 32 and an indicator 33 to driver circuits 34 which are arranged to open or close selected solenoid valves SV1 -SV1 0 as appropriate. Ten similar driver circuits are provided for this purpose, one for each solenoid valve. As will be described in greater detail below each circuit comprises a Schmitt trigger which generates a clearly defined on/off signal, and has an amplifier stage and an associated driver circuit to control the current supplied to the associated solenoid valve.When the operating temperature of the thermostat is to be adjusted an analogue output signal is generated at 29 which, as before, increases in 32 discrete steps from 0 to 6.3V when the "Temperature+" button is depressed and in decreasing steps when the "Temperature-" button is depressed and such signals, indicative of a selected operating temperature of the thermostat are used to drive a bar indicator 38 which provides an indication of that operating temperature.
When the thermostatically controlled mode is selected the output at 28 goes high (16V) and this occurs whenever the output at 27, the "heat rate adjustment" output goes to zero. The output at 28 is used to energise via a driver circuit (not shown), a relay switch 36 which energises the indicator 38 and also causes the switch 32 to connect the circuits 33 and 34, which control the operating condition of solenoid valves (SV1--SV10) represented at 35, to a source of an error signal (ERR) which is generated by a comparator 37. This signal is proportional to the difference between the operating temperature of the thermostat which is sensed and indicated at 38, and room temperature which is sensed at 39.In this way the rate of the fire is controlled by the error signal (ERR), and a desired steady state heat output rate will be achieved when the thermostat indicator and the room temperature indicator both indicate the same temperature, namely the operating temperature of the thermostat. An indicator 40, similar to that at 38 is also provided, to indicate the room temperature sensed at 39.
The ten step bar indicator 33, referred to earlier, comprises a proprietary integrated circuit which switches on a number (between 0 and 10) of light emitting bars proportional to the input voltage, being between 0 and 6.3V. This provides, therefore, an indication of heat output rate and so the number of solenoid valves which have been energised by means of the driver circuits 34.
Similarly, the bar indicator 38 also comprises an integrated circuit which switches in a number (between 0 and 10) of light emitting bars, in dependence on the output voltage (laying between 0 and 6.3V) generated at the output 29. These voltages correspond to room temperatures between 1 40C and 320C, each lit bar defining a temperature interval of 20C. Indicator 40 which operates in the same manner as indicator 38 represents the same range of temperatures and may be conveniently mounted adjacent thereto on the fire so that a direct visual comparison between the temperature setting of the thermostat and room temperature can be made. In addition to the above-mentioned temperature indicators a further indicator is provided to show when the mains power is connected to the fire.
Various components, reprsented in block schematic form in Figure 2 are now described in greater detail by reference to Figures 3a, 3b, 3c and 3d. The reference numerals used in Figure 2 are also used in Figure 3 to indicate corresponding components. In particular, the circuit diagram of the mixer is represented in Figure 3a by the chain dotted rectangle 23. Positive going, 1 6V pulses on a steady OV datum are fed to the mixer from the preampifier, shown at 21 in Figure 2, and are inverted by the resistor transistor circuit comprising R1, R2 and T1 and then applied to the anode of diode D1. Similar negative going pulses, generated by the push button transmitter 22, mounted to the body of the fire may also be applied to the anode of diode D1 via the diode D2.Irrespective of their source negative going pulses prevailing at the anode of D1 are re-inverted by the resistor R4 and transistor T2 and the resulting positive going signals passed to the receiver 24 for decoding. The transmitter 22 includes an integrated circuit-RS 490 (380-073)-which is wired in accordance with Figure 3a. This arrangement generates encoded signals which are identical to those generated by the remote hand control device 20, the duration of each binary ZERO being tuned by potentiometer P 1 0 so as to have an identical duration, and in this way signals derived from either source will be read by receiver 24 in the same way. Figures 3b and 3c show circuit diagrams of the two relay switching circuits illustrated in
Figure 2 at 30 and 36 respectively. Referring to Figure 3b, the 1 6V output at 26 is connected via resistor R6 to a driver circuit (IC307-092) which energises a relay RLA. Contacts on the relay switch the mains power to the main solenoid valve 1 2, to the igniter 14, to the visual display circuit 33 and to a transformer supplying the greater part of the control circuit. Similarly referring to Figure 3c a (1 6V) signal generated at 28 is connected via resistor R7 to another drive circuit which energises a further relay RLB. Contacts on the relay switch RLB serve to control the state of the switch shown at 32 in
Figure 2. The switch 32 is also shown in the circuit diagram of Figure 3d which illustrates in greater detail the components 31, 32, 33,34,35, 37, 38, 39,40.
When switch 32 is connected, as illustrated by the full lines, the heat rate indicator circuit 33 and driver circuits 34 are linked to the output location 27 of the receiver 24 and control of the heating rate is effected by direct operation the control device, 21 or 22. Alternatively, however, when the thermostatically controlled mode is selected the indicator circuit 33 and drive circuits 34 are coupled to the output of the comparator circuit 37, which, as described earlier generates an error signal, ERR.
This error signal is proportional to the difference between a signal, indicative of the operating temperature of the thermostat, derived at the output 29 of the receiver, and a signal indicative of room temperature, generated by the room temperature sensor circuit 39. In this mode of operation the thermostat temperature setting derived at the output 29 of the receiver is also applied to the thermostat temperature indicator 38.
The room temperature sensor circuit 39 includes an element TP which passes more current when hot than when cold e.g. a thermistor, and is chosen to have a linear response betwen 1 40C and 320 C.
ElementTP is placed across a 1 6V regulated supply in series with a resistor R10 and a potentiometer
P9 and a reference voltage REF is derived from a potentiometer, also placed across the 1 6V supply and consisting of the resistors R1 1 and R12 and potentiometer P2. A voltage generated across the element
TP is compared with the reference voltage REF and then amplified by an operational amplifier OA1 . The amplified difference signal indicative of the sensed temperature of the room is fed to the room temperature indicator 40 and also to one input terminal of an operational amplifier OA2 contained within the circuit 37.In this example, the potentiometers P 1, P2 and P9 are used to set the gain of the amplifier OA1 so that the voltage level produced at 1 40C at the input to the driver circuit BD3 of indicator 40 is only 1/10 that attained at 320 C.
The indicators represented at 33, 38 and 40 each comprise an LED bar array (LED1 to LED3, respectively) each having 10 bars which is driven by a respective bar drive BD1, BD2 and BD3. The output from BD1, the heat output rate indicator, is connected to two CMOS Hex inverting Schmitt triggers RS308-461 (INV 1) which are fed from a 5V supply. The Schmitt triggers turn on at input voltages exceeding 3.5V and turn off when the voltage falls below 1 .5V and series and parallel resistors R22, R23 are provided to enable the triggers to operative.
Nine driver circuits, each of the kind exemplified at 34 are used to control the solenoid valves other than SV5, one drive circuit being used to drive each valve. A transistor T3 amplifies the signal from the Schmitt Trigger INV1 and the transistor T4 then drives the solenoid valve. Diode D3 protects the circuit against inductive surges when switching the solenoids, and diodes D4 and D5 may optionally be provided to protect the transistor T4 against switching surges and reverse voltages respectively. The driver for solenoid valve SV5 is identical with the others but includes a timer circuit 31 which blocks the opening of SV5 for about 30 seconds after switching on the fire. The timer circuit comprises a transistor T5, an inverting Schmitt trigger T6, a resistor R3 1 a capacitor C4 and a diode
D6. When the 5V supply is switched on capacitor C4 begins to charge through resistor R3 1.The input to the Schmitt trigger therefore is initially low and its output high thus driving the transistor T5 and effectively blocking any signal applied through R29 to T3, thereby preventing energisation of SV5.
After about 30 seconds, C4 charges sufficiently to trigger T6 and its output goes low, thereby turning off transistor T5 and allowing SV5 to be opened.
It will be appreciated that although the invention has been described by reference to a particular embodiment, other embodiments encompassed by the invention will also be envisaged and one example of an alternative construction is illustrated in Figure 4. In this arrangement the supply of gas to the burners is controlled by a motor driven valve 50 rather than a plurality of solenoid valves as described above. A motor driven valve of this kind may have either a rotary or linear action and may be provided with outlet ports suitable for controlling both parts of a duplex burner or alternatively separate valves could be provided. In the illustrated example the valve 50 has an associated resistance potentiometer RP which generates an electrical signal indicative of the position of the valve, although a proximity switch or light operated device could alternatively be used.The control signals from switch 32, generated in response to coded signals selected by a user are passed to a comparator 51 which compares it with the signal indicative of the setting of the valve 50. If a difference exists, the difference signal is fed to motor 52 which drives the valve in a sense appropriate for reducing the difference signal, and in this way "homes in" on the correct setting. Circuits well known in the art may be employed to avoid overshoot and oscillations of the valve setting and the heat output rate may be monitored at 53. As before the valve may be operated in the "direct" mode in response to signals generated at 27 or alternatively in the "thermostaticaliy controlled mode" in response to an error signal
ERR generated at 37.
In another embodiment of the present invention the heat output rate of the fire may be controlled by the digital output from the programmed control pins 12, 13, 14, 1 5, (hereinafter referred to as A, B,
C, D respectively) of the receiver 24. The digital output signals generated at these pins are indicative of the heat output rate selected by a user and may be utilised in conjunction with a control logic circuit, represented at 60, in Figure 5, to energise driver circuits 61 which effect operation of six solenoid valves 62. The configuration of the valves SV1-SV6 and their associated by-pass restrictors R1-R6 is set out in Figure 6 and as described above by reference to Figure 1 the gas inlet is controlled by a main solenoid valve MSV.In Figure 6, gas supplied to the central burner passes through three solenoid valves SV1, SV2 and SV3 and three restrictors R1, R2 and R3, each valve/restrictor pair being in
parallel with the others. Similarly gas supplied to the outer burners passes through three further valve/restrictor pairs SV4, R4, SV5, R5, SV6, R6. The valve opening sequence for achieving an
increasing heat output rate is illustrated in the table of Figure 7a and the logic circuit 60 for causing this sequence is shown in Figure 7b, the output from this circuit being passed to the driver circuit 61.
The digital signals from the receiver 24 are applied to the logic circuit 60 via a 4-pole changeover relay
switch 63 or solid state multiplexer so that in the alternative thermostatically controlled mode an error
signal, ERR, converted to digital form by an A/D converter 64 may also be passed to the circuit 60. The
heat output rate may be displayed digitally at 65. This method of control is possible when the gas injection pressure is below the gas inlet pressure i.e. restriction is present, and in this example an injection pressure of 9 mb is used at full rate, 11 mb of the 20 mb inlet pressure being dropped in control. It has been found that an adequate range of selectable heating rates can be obtained if the restrictor valves are set so that the power from SV1/R1 is 0.9KW, SV2/R2 is 1.66 KW SV3/R3 is 3Kw,
SV4/R4 is 0.9Kw, SV5/R5 is 1.28 KW, SV6/R6 is 2.56 Kw.When SV1 and SV2 are opened together the rate is 2.3KW, when SV4 and SV5 are opened together the rate is 2.0KW and when SV4 and SV6 are opened together the rate is 3.0KW. In this example when the electric supply is first applied SV1
SV6 are closed and the fire will not be lit until the rate is increased from zero. The logic control circuit 60 therefore applies an inhibiting signal (INH) to the igniter and the timer 31 which delays their operation until SV1 and SV2 have been opened. Although the FFD, described earlier, could be used in this example it could be replaced by an ignition circuit similar to that described in our patent application 45159/76, this circuit being modified to prevent the gas supply to the burner being increased above the lowest rate until a flame has been sensed at the burner. The timer 31 would then also be unnecessary.
In another arrangement, shown in Figure 8 lin which the same reference numerals as in Figure 1 are used for the same features), the main solenoid valve is absent and the gas inlet 10 is coupled to the gas burners 4, 5 and 6 through tap 19 either directly, for manual control via conduits 7 and 8, or indirectly for remote control via the branches B 1 and B2 containing solenoid valves SVO--SV4 and SV5-SV9, respectively. With an arrangement of this kind, anticlockwise rotation of tap from the closed position ("OFF" in the drawing) effects manual control, in the manner described earlier by reference to Figure 1, whereas clockwise rotation effects remote control.In this example, the valve
SV10 and the corresponding restrictor R10 (shown in Figure 1) have been eliminated from Branch B2 and a solenoid valve SVO inserted into branch B1. This enables the supply of gas to the central burner 4 to be terminated remotely. The tap 1 9 may be retained in the OFF position by a detent which can be released by pushing the tap knob. The advantage of this alternative arrangement is that the fire can be controlled manually using conduits which are independent of those used for remotely controlled operation.
In a yet further embodiment of the invention (not illustrated), the timer 31 is replaced by a separate flame sensing unit which is arranged to energise the igniter and hold the gas supplied to the central burner at a low rate until such time as a flame is sensed when the igniter is de-energised and the gas supply is controlled in response to a coded signal transmitted to the fire, or to error signals generated by the thermostat control unit of the fire.
Modifications to the above-described embodiment will be envisaged by persons skilled in the art.
In particular, operation of the thermostat control could be improved by implementing additional room temperature and/or humidity sensors or by use of integral and/or differential control to reduce or eliminate the offset between the operating temperature of the thermostat and that of the room. An internal clock could be employed to turn on or regulate the fire in accordance with a predetermined programme. Also a coded infra-red signal could be used to sense any obstruction in front of the fire and so prevent the fire from turning on, or limit the heat output, until the obstruction has been removed.
It will be appreciated that although the above description relates to a remotely controlled system for a gas fire the invention is not so limited and can be applied to other forms of heater where ease of control by persons in the room is of advantage. Convector or forced convector heaters deriving heat from gas electricity or from a central heating unit via liquid or warm air could also be controlled in this way. Moreover, the invention is not limited to a remote control link established using infra-red radiation-ultrasonic or radio frequency radiation could alternatively be used for example.
Figures 9 to 21 illustrate an embodiment whose main differences to those embodiments mentioned previously are that it is simpler and it replaces, where possible, mechanical and electromechanical components with electronic logic circuitry in order to economise on costs. Where there is no difference between a component in this embodiment and in a previous one, then the previous reference is utilized again in the following description.
In the arrangement of burners and their supply lines shown in Figure 9, the Flame Failure Device valve has been deleted, its function now being one of the operations done by the electronic circuitry as explained below. The main solenoid valve has been deleted, and gas tap 66 has a position in which the burners and thermostat can be controlled using the remote control unit 67 of Figure 10 and a switch (not shown) which disconnects the main electric supply to the circuitry for the control unit mode at all times except when the tap is in the "Remote Control" position. Only four solenoid valves and associated restrictors are now used to control the rate of gas flow to the burners, but their relative positioning in the supply lines are chosen so as to provide six steps of gas flow rate. More specifically each solenoid valve is in series with its corresponding restrictor (e.g.R1 SV1 in series with R1) thereby enabling a reduction in the size of each solenoid, and each solenoid valve/restrictor pair is in parallel with the other pair in the same channel A or B. Three rates can be achieved in each channel by switching as follows:- Step Mode Effect
Low rate: SV1 Centre burner 4 operative
Rate 2: SV2 Centre burner 4 operative
Rate 3: SV1 +SV2 Centre burner 4 at full rate
Rate 4: SV1 +SV2+SV3 Centre burner 4 at full rate
and outer burners 5 and 6
operative Rate 5: SV1 +SV2+SV4 Centre burner 4 at full rate
and outer burners 5 and 6
operative
Full rate SV1 +SV2+SV3+SV4 All burners 4, 5 and 6 at
full rate.
This system requires a considerable pressure drop across it, for example at full rate approximately half the supply rate is required. Restrictors R5 and R6 are positioned in the "manual control" gas lines 7 and 8.
The control circuit for this embodiment, as shown in Figure 10, has no controls mounted permanently on the gas fire; however the remote control unit 67 can be detachably mounted on the fire in a position in which it can still operate the fire, thereby enabling the gas fire to have controls on its frame when the "remote" facility is not required.
The control unit 67 has only four push-buttons, of which two raise or lower the thermostat setting and two raise or lower the rate of gas flow under direct control, the gas fire changes from thermostat control to direct control when the thermostat setting is taken below the lowest indicated value. The gas fire is exinguished by turning the rate to zero under direct control, while the gas supply is turned off completely by moving the tap 66 to the off position.
The receiver 68 has only one analogue output which sets the thermostat temperature, the digital output setting the rate of the fire under direct control and the "mute" output selecting either direct control or control by thermostat. The three least significant digits of the digital output of receiver 68 are inverted to conventional binary form and fed to a multiplexer 70 which replaces the relay 36 which had switch 32 for selecting either thermostat or direct control in the previous embodiments.
The other input to the multiplexer is the error signal from the thermostat, converted to digital form by an A/D converter 71. The control to decide which of these two values is used to control the rate of the gas fire, is derived from the "mute" output of the receiver. This output is switched from "0" to "1" when the analogue setting of the thermostat goes to "0" and from "1" to "0" when the analogue is set to anything but "0". When the control is "0" the gas fire is under thermostat control.
LED bar display 72, driven by bar driver 72a, gives visual indication of the thermostat setting, the room temperature indicator being omitted in this embodiment.
A thermistor 73 senses the room temperature and provides an electrical output derived from it whose value is approximately proportional to the rise in room temperature above a reference level, for example 140C.
A comparator 74 compares the sensed room temperature with the setting on the thermostat and produces an output proportional to the difference between them, this being the "error" signal transmitted via the A to D converter 71 and the multiplexer 70 (when set for thermostat control) and used to control the rate of the gas fire through the solenoid valves 14 as described below. The
relation between rate and error signal is chosen so that the control "homes in" on the thermostat setting. The output from multiplexer 70, which represents the rate to which the fire is set, is fed to LED bar display 75 to provide a visual indication of this rate.The logic driving this display also produces an output at logic "1" when the fire is calling for heat and at logic "0" when it is not, this output being used to enable igniter 76 only when heat is cailed for and to set the start-up rate on the second input of the multiplexer 77.
Igniter 76 senses flame by its rectifying property and will only produce sparks when no flame is
sensed and when its control input is set to "1". It also produces a signal when flame is sensed to
switch multiplexer 77 from the second inputs A2, B2, C2 to the primary inputs Al, B1, Cl which
represent the rate at which the fire should be burning. Multiplexer 77 is used to control the start-up
sequence. The control is taken from the flame sense output of the igniter and at all times when no flame is present the multiplexer output Q1, 02, Q3 is connected to the second input A2, B2, C2. When there is no call for heat this input is "0" and the burners are therefore turned off. Where there is a call for heat then A2 is "1" and this is the output at Q1 thus turning the centre burner on at the lowest stable rate and applying ignition.
As soon as ignition is established, the "flame sensed" signal switches the multiplexer 77 to inputs Al, B1, C1 and the burner rate goes to that set by the receiver and its associated devices.
The logic unit 78, takes the 3-bit binary number and converts it to an output appropriate for switching the four solenoid valves in sequence to produce a suitably stepped gas rate.
The driver 79, is a unit capable of handling the electrical power needed to supply the four solenoid valves 80.
Figure 11 shows the wiring of the push buttons, P 1, P2, P3 and P4, and other components in the control unit 20' which uses an integrated circuit SL 490 manufactured by Plessey. The table in Figure 1 2 shows the code sent by the unit 67 in response to each push button (P) and the meaning which this code has in relation to the control of the gas fire. When power is switched on, the fire is under thermostat control which is set near the mean (2.8/6 V). If the thermostat is set to zero, the "mute" output operates so that the fire comes under direct control (operable using P 1 and P2). As mentioned before, when the direct control is set to zero the fire is turned off.
Table of push buttons operations
P number Pins connected Signal code Meaning 1 10-15 10101 Heat Step+
2 12 15 11101 HeatStep- 3 10-14 10110 Thermostat step+
4 12-14 11110 Thermostat step
Figure 12 shows the wiring of the unit 21 in which infra-red sensor 83 receives a signal from device 67 and converts it to an electrical signal which is amplified and filtered by an integrated circuit
SL480 manufactured by Plessey and referenced 82, before being passed on to receiver 68. Figure 13 shows the wiring of receiver 68 which incorporates an integrated circuit ML923 manufactured by
Plessey the coded signal from unit 21 being input at terminal 3.
The receiver 68 has an analogue output to comparator 74 for setting the thermostat and a "mute" output to multiplexer 70 for changing from thermostat to direct control and vice versa. Signal
A1, B, and C1 form a digital output to multiplexer 70 for direct control of the gas rate to the burner when the "mute" output is "1".
Figure 14 shows the wiring to multiplexer 70 in which an integrated circuit 451 9B takes either input Al, B1 C1 from receiver 68 or input A2, B2, C2 from the comparator 74 and, depending on the signal from the "mute" output of the receiver, passes one of them to the output which goes to multiplexer 77 and to the Digital to Bar logic 81 which drives LED display 75. When the signal from the "mute" output is "0" the output is connected to the A2, B2, C2 signal input.
Converter 71 inputs the analogue signal from comparator 74 and converts it to a 3-bit binary number. This number is an "error" signal, i.e. it is proportional to the difference between the actual room temperature and the temperature set on the thermostat. It is the output to the multiplexer 70 and, when the fire is under the control of the thermostat, this "error" signal is used to control the rate of the gas fire. Note that if this error signal becomes zero, then the fire will be turned off completely (see Figure 1 5). If preferred the logic can easily be modified to leave the burner on the lowest rate in these circumstances.
The outputs of bar driver 72a, shown in Figure 1 5, are normally "1", but they change to "O" in turn as each decimai digit is switched; thus A3 is "1" when the outputs from the bar driver are 1,3,5 or 7, similarly B3 is "1" when the outputs from the bar driver are 2, 3, 6 or 7 and C3 is "1" when these outputs are 4, 5, 6 or 7.
Figure 16 shows the circuitry connecting comparator 74, thermistor 73, a bar driver 72a and LED bar display 72 to indicate the setting of the analogue output of receiver 68'. The voltage across the room temperature sensing thermistor 73, which is in series with resistors, is compared with a set reference and the difference is amplified through an operational amplifier 73a. Using adjustable resistances and potentiometers the output of this amplifier is made proportional to the temperature rise above a certain fixed datum, e.g. 140C.
The gain of the amplifier is also set so that the temperature scale with voltage corresponds with that used for setting the thermostat at the analogue output of receiver 68.
The output of the operational amplifier 73a is compared with the analogue output of the receiver 68 and the difference is amplified by the operational amplifier, adjusted by a potentiometer and passed to the A to D converter 71.
Figure 17 shows the Digital to Bar logic unit 81 which drives LED display 75, whereby the binary number from the multiplexer 70 which represents the required burner rate of the gas fire is fed to the input of 4028B BCD/decimal decoder representing unit 81. The output from the decoder is used via suitable transistor switches 75a, to drive LED bar display 75 which indicates the rate at which the burner has been set. The output from pin 3, which switches to "1" only when all outputs A, B and C are equal to "O" is inverted and passed via terminal (1) to the igniter 10 and the multiplexer 70. This output indicates a call for heat as logic "1" and no call for heat as "O".
The igniter 76 shown in Figure 1 8 consists of a conventional spark generator circuit in which a thyristor TH 1 discharges capacitor C1 through the primary of transformer TR 1 thus producing a spark at spark gap SG2 which lights the flame at the burner. The spark current also passes through the controlled spark gap SG 1. A spark is thus generated everytime a pulse is received at the gate of thyristorTH1. Such pulses are generated by an astable flip-flop comprising gates NOR1 and NOR3. The frequency of these pulses (about 3 per second) is governed by the resistance R4 and capacitance C2.
The pulses are sent to the thyristorTH1 via capacitor C3 and pulse transformerTR2. The pulse transformer is necessary in order to protect the CMOS logic from damage if the N terminal were connected inadvertently to the live side of the supply. The pulses, and therefor the sparking, can be stopped by applying a logic "1" to the second input of NOR1. This is achieved through NAND1 either:
(a) By applying logic "0" to the input from unit 81. This indicates that there is no call for heat, no gas is coming through and the spark will always be suppressed, or:
(b) By applying logic "0" to the other input to NAND1 via NOT1 and NOT2. This is equivalent to applying logic "0" to the input of NOT1. Normally this input is at logic "1" from the 15v supply via resistance R6.
When flame is present at the burner and immerses the spark gap SG2 this flame produces a weak rectifying effect and since an alternating voltage is applied to the spark gap via the high resistance R1 and R3 there is net current drain away from the live electrode to earth.
Part of this current is drawn through R2 and R6, the capacitor C4 smoothing out residual AC ripple. The values of R6, R1, R2 and R3 are chosen so that the input of NOT1 is reduced to zero whenever flame is present at the burner.
It follows that, when flame is present, the sparking will always be stopped. Furthermore, a logic "1" will appear at the input to NOT2 and this is output to the multiplexer 77. The input A, B, C for multiplexer 77 (see Figure 19) is derived from the other multiplexer 70 and reprsents the burner rate to which the gas fire has been set. Of the other inputs B4 and C4 are always "0", A4 from the output of the Digital bar logic unit 81 driving LED75), is "0" when there is no call for heat and is "1" if heat is called for. The "control" of the multiplexer 77 is connected to the "flame sense" output of the igniter 76 and to the output of the Digital bar logic through an AND gate. It is only "1" when flame is sensed and when there is a call for heat, and these are the conditions when it will switch inputs A, B, C to the outputs 01, Q2, 03.In these conditions the burner rate will be that set by the multiplexer 70.
In any other conditions the output will be connected to A4, B4, C4. If there is no call for'heat A4,
B4, C4 are 0 and the burner will be turned off. If there is call for heat but no flame A4 is 1 and the burner will be lit at lowest rate. As soon as flame is established the multiplexer will switch over via the
AND gate and its output will be A, B, C, i.e. the full rate to which the burner is set.
Logic unit 78 (see Figure 20) converts the digital output 01, Q2, 03 from multiplexer 77 to the desired sequence of opening of the solenoid valves.
The truth table is as follows:- Digital output from
Burner multiplexer (77) Solenoids energised
rate
step No. 03 Q2 Q 1 4 3 2 1
off 0 0 0 0 0 0 0
1 0 0 1 0 0 0 1
2 0 1 0 0 0 1 0
3 0 1 1 0 0 1 1
4 1 0 0 0 1 1 1
5 1 0 1 1 0 1 1
6 1 1 0 1 1 1 1
7 1 1 1 1 1 1 1
Note that the rate dwells on step 6 for both of the last two binary inputs (110 and 111). This is to reduce the risk of inadvertently turning the fire off when setting full rate.
If the "Heat+" button is pressed continuously then that binary output 01, 02, Q3 will cycle continuously going back to 000 after passing through 111. The effect is similar to a gas tap without any end stops that can be rotated continuously from "Off" through "Low", "Medium" and High and then round to "Off" again. It has a certain advantage in being able to switch quickly from full-on to off or vice-versa. Figure 20 shows one form of logic circuit to achieve this 'truth table'.
Driver 79 is a conventional circuit to handle the power needed to operate the solenoid valves which are also shown in Figure 20.
The power supply which is shown in Figure 21 is isolated from the mains by a transformer 90 and bridge rectifier 91 which produces a smoothed 24 volt DC supply with negative earthed. This is used to power the solenoid valves. A regulated 1 5 volt supply is derived from the 24 volt output using a conventional voltage regulator 92. This is used for the rest of the control circuitry. A well regulated supply is particularly needed for the thermostat temperature senspr and the pre-amplifier.
Claims (9)
1. Domestic heating apparatus comprising means for regulating an operational parameter of the apparatus, means for receiving transmitted coded signals indicative of a selected value of said parameter and generated at a location remote from the apparatus, and means responsive to received signals for controlling the regulation means so as to attain the selected value of said parameter.
2. Domestic heating apparatus comprising means for regulating an operational parameter being the heat output rate, means for receiving transmitted coded signals indicative of a selected rate and generated at a location remote from the apparatus, and means responsive to received signals for controlling the regulation means so as to attain the selected heat output rate.
3. Apparatus according to Claim 1 or Claim 2 wherein the apparatus is a gas fire.
4. Apparatus according to Claims 1, 2 or 3 comprising means for manually regulating said operational parameter.
5. Apparatus according to Claim 3 in combination with Claim 4 comprising a first passageway for supplying gas from the regulation means to the fire burner during remote operation and, separate from the first passageway, a second passageway for supplying gas from the regulation means to the fire burner during manual control.
6. Apparatus according to any of Claims 3 to 5, wherein the regulation means comprises a plurality of selectively operable valves for regulating the gas supply to the burner.
7. Apparatus according to any one of the preceding claims, wherein the signals are digitally encoded.
8. Apparatus according to any one of Claims 3 to 7 comprising a means for sensing a flame comprising means to control the supply of gas and the ignition of a flame.
9. Domestic heating apparatus substantially as hereinbefore described with reference to and as illustrated in Figures 1,2 and 3 or Figure 4 or Figures 5,6 and 7 or Figure 8 or Figures 9 to 21 of the accompanying drawings. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8212604A GB2099607A (en) | 1981-05-01 | 1982-04-30 | Heating apparatus control system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8113535 | 1981-05-01 | ||
GB8212604A GB2099607A (en) | 1981-05-01 | 1982-04-30 | Heating apparatus control system |
Publications (1)
Publication Number | Publication Date |
---|---|
GB2099607A true GB2099607A (en) | 1982-12-08 |
Family
ID=26279319
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8212604A Withdrawn GB2099607A (en) | 1981-05-01 | 1982-04-30 | Heating apparatus control system |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2099607A (en) |
Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2126758A (en) * | 1982-09-03 | 1984-03-28 | Valeron Corp | Machine system using infrared telemetering |
GB2129988A (en) * | 1982-10-02 | 1984-05-23 | Smith & Nephew Ass | Patient support means |
GB2197106A (en) * | 1986-11-04 | 1988-05-11 | Christopher Douglas | Monitoring and control system |
GB2213255A (en) * | 1987-12-04 | 1989-08-09 | Valor Heating Ltd | Gas-fired appliance |
US4962750A (en) * | 1989-11-06 | 1990-10-16 | R. H. Peterson Company | Remote control of gas fireplace burner |
GB2230367A (en) * | 1989-03-31 | 1990-10-17 | Lutron Electronics Co | Remotely controllable power control system |
US5333596A (en) * | 1992-03-23 | 1994-08-02 | Clifford Todd W | Outdoor cooking grill provided with vending apparatus |
EP0617351A2 (en) * | 1993-03-15 | 1994-09-28 | TEMIC TELEFUNKEN microelectronic GmbH | Processing of control information for HVAC system |
GB2280291A (en) * | 1993-07-20 | 1995-01-25 | Nicholas Weiner | Control of equipment |
US5450841A (en) * | 1993-05-18 | 1995-09-19 | Gmi Holding, Inc. | Multi-function remote control system for gas fireplace |
US5555509A (en) * | 1993-03-15 | 1996-09-10 | Carrier Corporation | System for receiving HVAC control information |
US5617840A (en) * | 1992-03-23 | 1997-04-08 | Convenience Technologies, Inc. | Cooking grill |
EP0821777A1 (en) * | 1995-04-19 | 1998-02-04 | Bowin Technology Pty Limited | Heating appliance |
US5813394A (en) * | 1992-03-23 | 1998-09-29 | Convenience Technologies, Inc. | Cooking grill with moisture-insensitive flame detector |
GB2336045A (en) * | 1998-03-31 | 1999-10-06 | Exodus Electronic Ltd | Remotely controllable electrical switching apparatus |
GB2302965B (en) * | 1995-07-04 | 1999-11-24 | Legge Fabheat Limited | A gas fire assembly |
US6116230A (en) * | 1992-03-23 | 2000-09-12 | Convenience Technologies, Inc. | Microprocessor-controlled gas appliance utilizing a single electrode spark ignition system and a pulse width modulated proportional valve |
US6119680A (en) * | 1998-07-31 | 2000-09-19 | Maytag Corporation | Ventilation system for an appliance |
US6650029B1 (en) | 1998-03-31 | 2003-11-18 | Exodus Electronic Limited | Remotely controllable electrical switching apparatus |
-
1982
- 1982-04-30 GB GB8212604A patent/GB2099607A/en not_active Withdrawn
Cited By (26)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2126758A (en) * | 1982-09-03 | 1984-03-28 | Valeron Corp | Machine system using infrared telemetering |
GB2129988A (en) * | 1982-10-02 | 1984-05-23 | Smith & Nephew Ass | Patient support means |
GB2197106A (en) * | 1986-11-04 | 1988-05-11 | Christopher Douglas | Monitoring and control system |
GB2213255A (en) * | 1987-12-04 | 1989-08-09 | Valor Heating Ltd | Gas-fired appliance |
GB2230367B (en) * | 1989-03-31 | 1993-03-24 | Lutron Electronics Co | Remotely controllable power control system |
GB2230367A (en) * | 1989-03-31 | 1990-10-17 | Lutron Electronics Co | Remotely controllable power control system |
US4962750A (en) * | 1989-11-06 | 1990-10-16 | R. H. Peterson Company | Remote control of gas fireplace burner |
US5617840A (en) * | 1992-03-23 | 1997-04-08 | Convenience Technologies, Inc. | Cooking grill |
US5333596A (en) * | 1992-03-23 | 1994-08-02 | Clifford Todd W | Outdoor cooking grill provided with vending apparatus |
US6382961B2 (en) | 1992-03-23 | 2002-05-07 | Convenience Technologies, Inc. | Microprocessor-controlled gas appliance utilizing a single electrode spark ignition system |
US6220854B1 (en) | 1992-03-23 | 2001-04-24 | Convenience Technologies, Inc. | Microprocessor-controlled gas appliance utilizing a single electrode spark ignition system and a pulse width modulated proportional valve |
US6116230A (en) * | 1992-03-23 | 2000-09-12 | Convenience Technologies, Inc. | Microprocessor-controlled gas appliance utilizing a single electrode spark ignition system and a pulse width modulated proportional valve |
US5813394A (en) * | 1992-03-23 | 1998-09-29 | Convenience Technologies, Inc. | Cooking grill with moisture-insensitive flame detector |
US5555509A (en) * | 1993-03-15 | 1996-09-10 | Carrier Corporation | System for receiving HVAC control information |
EP0617351A3 (en) * | 1993-03-15 | 1995-02-08 | Telefunken Microelectron | Processing of control information for HVAC system. |
EP0617351A2 (en) * | 1993-03-15 | 1994-09-28 | TEMIC TELEFUNKEN microelectronic GmbH | Processing of control information for HVAC system |
US5450841A (en) * | 1993-05-18 | 1995-09-19 | Gmi Holding, Inc. | Multi-function remote control system for gas fireplace |
GB2280291A (en) * | 1993-07-20 | 1995-01-25 | Nicholas Weiner | Control of equipment |
EP0821777A1 (en) * | 1995-04-19 | 1998-02-04 | Bowin Technology Pty Limited | Heating appliance |
US5984663A (en) * | 1995-04-19 | 1999-11-16 | Bowin Technology Pty. Ltd. | Gas fueled heating appliance |
EP0821777A4 (en) * | 1995-04-19 | 2000-04-12 | Bowin Tech Pty Ltd | Heating appliance |
GB2302965B (en) * | 1995-07-04 | 1999-11-24 | Legge Fabheat Limited | A gas fire assembly |
GB2336045A (en) * | 1998-03-31 | 1999-10-06 | Exodus Electronic Ltd | Remotely controllable electrical switching apparatus |
GB2336045B (en) * | 1998-03-31 | 2002-11-27 | Exodus Electronic Ltd | Electrical switching apparatus |
US6650029B1 (en) | 1998-03-31 | 2003-11-18 | Exodus Electronic Limited | Remotely controllable electrical switching apparatus |
US6119680A (en) * | 1998-07-31 | 2000-09-19 | Maytag Corporation | Ventilation system for an appliance |
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Legal Events
Date | Code | Title | Description |
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WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |