GB2515462A - Control assembly for a gas fire - Google Patents

Abstract

A control assembly for a gas fire has an adjustable control valve 13 having an inlet 19 for the ingress of combustible gas and an outlet 15, 16 for the egress of combustible gas. The control valve is adjustable from a closed configuration in which flow of gas through the valve is prevented, to an open configuration in which flow of gas through the valve is permitted. The control assembly also includes a flame failure device 17 configured to close off the supply of combustible gas to the control valve. The control assembly includes a slide assembly 5 having a slot (1, fig 1) and a knob 7. Sliding the knob down the slot operates a control lever 11 through a linkage 9. The lever operates a switch 23 which activates an igniter 25 operated by a battery 27. The flame failure device is linked to a thermocouple 29 which keeps the flame failure device open when a flame is present.

Description

I

DESCRIPTION

CONTROL ASSEMBLY FOR A GAS FIRE

The present invention relates to control assemblies for gas fires and to a gas fire incorporating such a control assembly.

More particularly, but not exclusively, the present invention relates to a control assembly for use in controlling a gas burner in a radiant convector or a simulated sofid fuel gas fire. Conventionally, a simulated solid fuel gas fire comprises a bed of randomly arranged simulated solid fuel element, e.g. coals and/or logs, located within a fireplace opening which connects with a flue and which usually has a decorative surround. The simulated solid fuel elements rest on a gas burner usually comprising a tray filled with sand, vermiculite or the like through which a gas/air mixture supplied via a control valve arrangement Is passed.

The control valve arrangement for the gas/air mix Is located below the tray, i.e. below the bed of simulated coals and/or logs and is normaHy located behind a removable decorative fender.

Similarly, in certain radiant convector fives, especially flush fitting radiant convector fires, the control valve arrangement is located behind a decorative fender in the lower part of the fire, in EP-A-0704041, the control valve arrangement is In the form of an adjustable rotary gas flow control valve located downstream oF a flame failure device. The flame failure device is either in an "open" or "ded0 condition, depending upon the detection of a flame by a thermocouple. When the flame failure device Is "open", gas is fed to the gas flow control valve which Is rotatable between a maximum open position and a minimum open position. The gas flow control valve is operated by means of a pivotable control lever which can be adjusted by a slide control. In order to ignite the gas fire to which the control valve aimngement Is connected, the pivotal control lever Is pivoted to a position In which It physically opens the flame failure device to allow gas to flow to the gas flow control valve. In thIs position, the control lever also closes a microswltch which actuates an igniter to ignite the gas fed to the gas burner. Once the thermocouple has warmed up sufficiently, the flame failure device is held open and it is no longer necessary for it to be held open physically by the control lever.

In order to switch off the gas fire, the control lever Is pivoted to the extreme opposite position, in which It closes a second mlcroswltch which In turn actuates an interrupter connected to the flame failure device, which closes the flame faIlure device and thereby stops the flow of gas to the gas control valve.

One potential problem with the above arrangement is that the output generated by the thermocouple which holds the flame failure device open, Is very small (typically a few millivolts) and is relatively unstable. Moreover, the low output from the thermocouple Is required to flow through a relatively high resistance switch and interrupter before entering the magnetic valve within the flame failure device. Any suspensIon or interruption of the current from the pilot flame In which the thermocouple is held will Immediately result in closure of the flame failure device, which results In occurrences of unwanted and urnecessary shutdown. This problem Is more prevalent than might be expected, sInce flue restrlctors are not always fitted when they should be. In such circumstances, high flue flows result which In turn result In increased fluctuation of the pilot flame and increase In the frequency of nuisance' shutdowns.

It is an object of the present invention to provide a control assembly for a gas fire which overcomes or alleviates the above problems.

In accordance with the present tiventlon, a control assembly for a gas fire comprises an adjustable control valve having an inlet for the ingress of combustible gas and an outlet for the egress of combustible gas, the adjustable control valve being adjustable from a dosed configuration in which flow of gas through the valve is prevented to an open configuration in which flow of gas through the valve is permitted, the assembly fUrther comprising a flame faHure device configured to dose off the supply of combustible gas to the adjustable control device, With the above arrangement, switching off the gas fire is achieved manuafly, by adjusting the control valve to its dosed configuration. This results in cutting off the supply or combustible gas which in turn wifi result in dosing of the flame failure devce as the combustion flames in the gas fire wl cease.

The arrangement aHows the removal of the switch and interrupter of the prior art described previously, which allows the signal from the flame sensor supphed to the flame failure device to be monitored much more precisely and without giving rise to as many spurious shutdowns.

In a preferred embodiment, the adjustable control valve is a rotary valve The rotary valve is preferably controfled by a control ever, Said control lever is preferabiy movable between two end positions of available movement.

Preferably, in one of said end positions, the adjustable control valve is in a closed configuration.

The control valve assembly may further comprise a switch operable by the control lever to activate an igniter towards one end region of the available pivotal movement of the control lever, Preferably, the flame failure device is physically engageable and openable by the movement of the control lever towards said one end region of the available movement of the control lever.

The flame failure device may comprises an atmosphere sensing device.

The atmosphere sensing device may comprise an oxygen depletion sensor, By way of example only, specific embodiments of the present invention will now be descrIbed, with reference to the accompanying drawings, In which: Fig. I is a perspective view of part of a gas fire incorporating a control siniUar to that descilbed in EP 0704041; Ag. 2 Is an illustration of an embodiment of control assembly for the gas fire of Fig. 1; and FIg. 3 Is an illustration of a modified form of linkage which can be used wIth the control assembly of Fig. 2.

With reference to FIg. 1. a "slidet control is located in the upper lateral periphery of the front face of a gas fired heater which is to be located in a fire place opening, although the slide control can be located at other positions on the heater. From the exterior of the fire, the slide control comprises an elongate aperture I through which part 3 of a slide member 5 projects, with a knob 7 secured to the slide member 5 both for aesthetic reasons and ease of operation.

By manually moving the knob 7 along the aperture 1, the slide memberS moves in the direction "At or "Be, as seen in Fig 2. The lower end region 8 of the slide members is pivotally connected to one end region of an elongate linkage 9, the other end region of a linkage 9 being pivotally connected to a pivot control lever 11. PIvotal movement of the control lever 11 adjusts an on-off and control valve 13 which in use controls the supply of combustible gas to a burner feed passage 15 and to a passage 16 leading to a pilot flame.

Movement of the slide member 5 upwards in direction t" to its maximum extent physically closes the valve 13 so that no gas can flow through it.

Movement of the slide member 5 downwards In direction "A" away from position B" causes the valve 13 to assume an open configuration, the extent of opening being adjusted by the degree to which the slide memberS is moved downwardly.

Movement of slide member 5 downwardly to its maximum downward extent, as shown In Ag. 2, causes the control lever 11 to engage and depress a spring-loaded plunger 14 extendSig from a flame failure device 17, which physically opens the flame failure device and allows gas to flaw from an inlet 19, via a regulator 21, thugh the het&open flame failure device and through the opened valve 13. In this position, the control lever also trips a microswltch 23 located In the vicinity of the gas control valve 13, which activates an electronic igniter 25, powered by a battery 27, whereby gas fed to the burners and the pilot flame output of the heating appliance is ignited. By holding the knob 7 In the lowermost position, as shown in Ag. 2, the flame failure devIce 17 is physically held open. However, the pilot flame eventually heats the thermocouple 29 of an oxygen depletion sensor (ODS) or other atmosphere sensing device (ASO) sufficiently to maintain the flame failure device open, whereupon the Knob 7 can be moved slightly upward in direction B" to rSease the plunger 14 and the microswltch 23 and to adjust the gas flow control valve 13 to control the feed of gas to the burners in order to achieve the required performance for the fire.

In a particular embodiment Illustrated, when the Knob 7 is in the lowermost position of the aperture I (shown In Fig. 2), the gas flow control valve is adjusted to provide a minimal, but nonzero, gas flow. The flow of gas is increased towards a maximum by movement of the Knob upwards in direction B". When the fire is to be switched off, the knob 7 is moved upwards in direction "B" to its maximum position, in which the gas control valve 13 assumes a closed configuratIon. This cuts off the supply of gas to the burners which is in turn detected by the 005 or other MD, resulting in closure of the flame failure device 17.

In an afternative arrangement, the degree to which the valve 13 is open after moving from its closed position increases as the knob 7 a moved downwardly in direction 8.

WhUst a rigid linkage shown in Hg 2 comprises a single elongate member 9. other linkages can he substituted as desired. For example, in the arrangement shown in Fig. 3, a Bowden cable 35 is boated between the slide member 5 and the control ever 11 The invention is not restricted to the details oF foregoing embodiment&