US2746534A

US2746534A - brqoks etal

Info

Publication number: US2746534A
Authority: US
Publication date: 1956-05-22
Anticipated expiration: 1973-05-22

Description

May 22, 1956 E. G. BROOKS ET AL SAFETY CONTROL MEANS FOR GAS APPLIANCES Filed Jan. 5, 1955 United States Patent SAFETY CONTROL MEANS FOR GASAPPLIANCES Ernest George Brooks, Sandcrstead, and James Edward Cooper, Carshalton Beeches, England, assignors to Thomas De La Rue & Company Limited, London, England, a company of Great Britain 7 I Application January 5, 1953, Serial No. 329,712 Claims priority, application Great Britain February 4, 1952 9 Claims. (Cl. 158-129) This invention relates to safety control means for gas appliances, such as a gas water heater, the object of the invention being to provide control means whereby gas from the main burner cannot issue therefrom until certain parts of the supply system are operated in a predetermined sequence.

Safety control means according to the present invention comprises a cock or tap controlling supply of mains gas to a main burner, a pilot jet in direct communication with the gas mains supply, a pressure responsive type cut-01f valve including a manually operable control, and an electro-magnetic device, energizable by a thermo-cou- .ple heated by the pilot jet, said electro-magnetic device co-operating with the cut-off valve, and also including a manually operable control, so that the main flow of gas cannot pass to the main burner until the main burner cock is in the closed position and the manually operable controls are operated in pre-arranged sequence.

The pressure type cut-ofi valve structure preferably comprises a valve body having adivision wall therein to divide the body into twomain compartments, one, the first of which, is in open communication with the gas mains supply and contains a valve seating for a valve,

the division wall being apertured to allow the valve spindle to pass therethrough into the second compartment. The valve is carried by a flexible diaphragm which divides the second compartment into two chambers and V the valve spindle carries a small sealing diaphragm disposed within the second compartment and which surrounds the aperture in the division wall. The valve structure is capable in one position of sealing the main flow passage of gas 'to the burner and preventing flow of gas into the second compartment, whilst in the division wall a hand operated valve means is provided to establish communication between the two compartments when the valve rests on its seating.

The said second compartment is in communication with the electro-rnagnetic device through a weep pipe,

said electro-magnetic device, preferably comprising a bored body formed into two chambers, in one of which a magnet and armature are housed, the other chamber housing a pressure controlling valve operated by the electro-magnetic device, which valve is biassed onto a seating to allow gaseous pressure to buildup in the weep pipe.

One form of safety control means according to this invention, as applied to a gas water heater, is illustrated in the accompanying drawing, and is shown diagrammatically in the heater circuit lay-out.

Referring to the said drawing, the gas mains supply is shown at 1 and, through a branched pipe 1a, leads to a pilot jet 2, a pilot control cock 3 being provided, although this isnot essential. In the mains supply is arranged a cock 4, although again this is not essential to the invention, the supply leading through a constant pressure governor indicated generally at 5, of known construction, to a control valve indicated generally at 6. Part of the Patented May 22, 1956 control valve body is in communication through a weep pipe 7 with an electro-magnetic device indicated generally at 8, the electro-magnetic device including a thermoelectric valve and being normally mounted On the gas appliance. The mains pipe 1 .leads through the control valve 6 to a relay control valve 9, also of known construction, and which forms no essential part of the invention, which relay control valve is operatedby an immersion thermostat device 10 provided On a weep pipe 11. The immersion thermostat again forms no essential feature of the invention and may be replaced by any other valve for the purpose of achieving thermostatic control, and preferably the control is either that known as the onofi or the high-low working valve. Beyond the relay control valve 9 is provided a cock or tap 12, which is the mains control for supplying gas to the main burners 13, within the water heater 50. Mounted in the appliance adjacent the pilot 2 is a thermo-couple 14 connected by leads 36 to the electro-magnetic device 8.

i The safety control means constituting the invention consists'of two main components, the control valve 6 and the thermo-electric valve 8.

The control valve 6 is divided into two main compartments by a circular. centre division wall 15 incorporating a division plate 16. The lower compartment 17 forms the main gas way, gas cntering'at 18 from the mains supply 1 and flowing past a valve seating 19 to the outlet 20, leading to the relay control valve 9. The upper compartment is itself divided into two chambers by a flexible diaphragm 21. The lowerchamber 22 is in permanent communication with the thermo-electric or pressure controlling valve 8 via the weep pipe 7, whilst the upper chamber 23 is in communication with atmosphere via a vent 24. In the lower compartment 17 works a valve element 25 which is adapted to seat on the seating 19, the valve being normally closed on to its seating due to the provision of a weighted disc 26 forming part of the diaphragm 21 and mounted on the'valve element. The valve element may include a spindle 27 arranged to move freely through the hole in the centre of the division plate 16, but gas is prevented from passing through the hole in the division plate by a small flexible sealing diaphragm 28 secured to the division plate and around the valve spindle. The valve spindle itself is bored to provide a small gas passage 29 so that, when the valve 25 is in the open position, the gas can flow through the passage 29 into the chamber 22. Also mounted in the centre section 15 of the control valve body is a spring loaded push button 30 which enables gas from the inlet 18 to flow into the chamber 22 through orifices 31 when the button is operated, the button being ahand control. j

The weep pipe 7 communicates with the thermo-electric valve at 32 and can communicate through a vent 34 in the thermo-electric valve casing to atmosphere, when the thermo-electric valve is opened. In the thermo-electric valve casing there is provided an electro-magnet 35 coupled by leads 36 to the thermo-couple 14, and an armature 37 which is mounted on a spindle 38 terminating in a collar 39. The valve is shown at 33 and is a sliding fit on the spindle 38, and the valve is normally maintained in the shut position, that is to say on its seating, through bias of a compression spring 40, providedthat the armature 37 is held attracted by the electro-magnet 35 against a spring 41. In the event of theelectro-mag net being de-energised, the spring 41 withdraws the armature upwards so that the shoulder 42 on the spindle 38 engages the valve 33 and lifts it oif its seat. If the electro-magnet is re-energised the force of attraction is insufficient tore-seat the armature on the magnet, and in order to allow the 'electro-magnet to re-attractthe armature and hold it attracted, a hand-operated spring-loaded push button 43 is provided which, on depression, moves the armature 37 onto the electro-magnet 35.

The system works in the following manner: In order to light the appliance the burner cock 12 isrnoved to the closed position and the cock 4, if it is used, is also closed. The pilot control cock 3 is opened and the pilot burner lit. This heats the thermo-couple 14 and therefore energises the magnet 35, but, as has already been previously pointed out, the armature is not attracted and held attracted, due to the provision of the spring 41. The cock 4- is turned on, thus allowing gas to reach the control valve 6, but it will, of course, be appreciated that the valve 25 remains shut under the action of the weight 26 until gas under sufficient pressure can reach the underside of the diaphragm 21, that is to say until the gas can enter the chamber 22. In order that the valve 25 may be raised off its seat 19 the push button 43 is depressed, which allows the armature 37 to make contact with the electromagnet 35, where it is held attracted due to the thermocouple 14. The valve 33 is thus closed and so seals off the weep pipe 7 from communication with atmosphere through vent 34. border to allow access of gas through the inlet 18 to the chamber 22, the push button 30 is now operated so that gas passes through the apertures 31 into the chamber 22, but escape through the weep pipe 7 is blocked and the gas therefore passes down the passage 29 to the outlet side of the control valve. Provided the burner cock 12 is closed, gas pressure will build up under the diaphragm 21 until the pressure is sufiicient to lift the valve oh its seat, thereby allowing gas to flow through the outlet 20 as far as the main burner cock 12. This can then be turned on and gas will be admitted to the main burner 13, where it will be ignited by the flame from the pilot 2.

In the event of gas pressure failing or falling below a predetermined minimum the pressure under the diaphragm 21 falls, and thus the valve 25, due to its weighted disc 26, closes onto its seating 19 almost immediately, and thus the main burner goes out.

Assuming the gas pressure merely falls below a predetermined minimum so that the pilot still remains alight the burner cock 12 must be turned off and in order that the main burners may again be re-lit it is of course requisite that the gas mains supply should be restored to full pressure. When this occurs the hand operated push button 3i) must be depressed for a sufficient length of time to allow gas pressure to build up under the diaphragm 21. Communication between the weep pipe 7 and vent 34 is prevented by the valve 33 being on its seating, and therefore pressure can build up in the chamber 22 sufliciently to allow the diaphragm 21 to actuate, through the weighted disc 26, the valve 25 to open the valve, so that gas flows 7 through the pipe 1 to the burner cock 12 and this can then be opened and the burners lit.

If on the other hand the pressure fails the pilot flame is, of course, also extinguished. On restoration of the supply gas is admitted to the control valve 6, the valve 25 of which remains shut until the following sequence of events has occurred. First the pilot flame has been re-lit and the thermo-electric valve 8 has been re-set by means of the push button 43, so that the armature 37 will remain attracted by the magnet 35 through the thermo-couple 14. Secondly the burner cock 12 must have been turned off and thirdly the button 30 must have been depressed for sufficient length of time to build up gas pressure under the diaphragm 21. When this occurs the valve 25 is lifted off its seat, the burner cook 12 can then be opened, and the burner lit.

Should for any reason the pilot flame become extinguished the thermo-couple 14 cools and the electro-magnet 35 is de-energised so that the valve 33 is opened under the action of its spring 41. In these circumstances gas from the chamber 22 is released at a greater rate, through the weep pipe 7 to atmosphere, then it can enter 4 through the passage 29 in the valve spindle 27, so that the diaphragm and weight 26 causes the valve 25 to close.

Finally it will be appreciated that the system is still safe even in the face of an unexpected fracture, for example in the Weep pipe 7, because in these circumstances the escape of gas will cause the valve 25 to return to its seating and therefore cut off the main burner.

We claim:

1. Safety control means for gas fired appliances and adapted for installation in a gas line connecting the main burner of an appliance with the gas supply, said control means comprising a pressure responsive cut-01f valve in said gas line for preventing the flow of gas from said gas supply to said main burner when said cut-off valve is in its closed position; a cock in said gas line between said cut-ofl valve and said main burner for controlling the flow of gas to said main burner; a gas bleed passage connecting said cut-off valve and said gas line between said cut-off valve and said cock when said cut-off valve is in its closed position; a pilot jet; means by-passing said cutoff valve and said cock and connecting said pilot jet to said gas supply; a pressure controlling valve in communication with said cut-oif'valve for controlling the action of said cut-off valve; an electro-magnetic device for controlling said pressure controlling valve; a thermocouple adapted to be heated by said pilot jet for energizing of said electro-magnetic device; first manually operable control means in said cut-off valve; and second manually operable control means in said electro-magnetic device, said first and second manually operable control means being cooperable to open said cut-ofii valve and permit gas to flow to said main burner only after said cock and said manually operable control means are operated in predetermined sequence.

2. Safety control means as set forth in claim 1 including means biasing said pressure control valve toward its open position, said electro-magnetic device exerting insuflicient attraction when energized to cause said pressure control valve to close in opposition to said biasing means, said electromagnetic device exerting suflicient attraction when energized to hold said pressure control valve in its closed position when said second manually operable control means is operated to close said pressure control valve.

3. Safety control means as set forth in claim 1 wherein said cut-01f valve comprises a movable valve element; a valve body; an apertured division wall in said valve body dividing said body into first and second compartments; the first compartment being in open communication with said gas line; a seating in said first compartment on which said movable valve element may seat to seal gas passage to said main burner; a flexible diaphragm carrying said valve element and dividing said second compartment into upper and lower chambers; said first manually operable control means comprising a hand operated valve means provided in said division wall and being operable to establish communication between said first and second compartments when said movable valve element rests on its seating.

4. Safety control means as set forth in claim 3 including a weep pipe establishing permanent communication between said lower chamber and said pressure controlling valve, said upper chamber being vented to atmosphere.

5. Safety control means as set forth in claim 4 wherein said gas bleed passage is provided by a bore in said valve element, said bore extending between said first compartment and said lower chamber.

6. Safety control means as set forth in claim 3 wherein said pressure controlling valve comprises a bored body formed into first and second chambers and said electromagnetic device comprises a magnet and an armature housed in said first chamber; a movable valve member housed in said second chamber; a seating for said movable valve member in said body; means biasing said movable valve member toward its seating whereby gas pressure may be built up in said Weep pipe when said movable valve member is on its seating; and means biasing said armature out of engagement with said magnet, said movable valve member being seated on its seating only when said armature is held attracted by said magnet against the action of said armature biasing means.

7. Safety control means as set forth in claim 6 wherein said second chamber of said bored body includes a vent 9. Safety control means as set forth in claim 1 wherein said movable valve element is biased toward its seating by a weighted disc forming part of said diaphragm;

References Cited in the file of this patent UNITED STATES PATENTS 2,185,423 Andersen Jan. 2, 1940 2,291,567 Wunsch et a1 July 28, 1942 2,305,915 Wantz Dec. 22, 1942 FOREIGN PATENTS France Aug. 10, 1942