Fully automatic flame protection device
US 3185203 A
Description (OCR text may contain errors)
May 25, 1965 R. HASSA 3,185,203
FULLY AUTOMATIC FLAME PROTECTION DEVICE Filed April 25, 1963 United States Patent 3 Claims. cl. 153-125 This invention relates to a fully automatic flame protection device, and has as its object to provide an improved device of the general kind disclosed and described in my application No. 102,273, now Patent No. 3,145,- 762, filed April 11, 1961, the disclosure of which is incorporated herein by reference. The latter application provided a pilot or main burner flame to act on one or more thermocouple elements to control a first relay in such a way that when said flame is not burning it initiates an ignition process and keeps the main gas valve closed; but when the said flame is burning it stops the ignition process and opens and keeps open the main gas valve, and in which a second relay is provided in circuit with the said first .relay and arranged in case of current failure to close at one said main gas valve and to keep that valve closed until the thermoelectric current, again flowing due to the restarted ignition process initiated by said first relay, resets said first relay and reopens the main gas valve.
The present invention improves and modifies this device by allowing the device to control a plurality of burners.
According to the present invention there is provided an electrically operated fully automatic flame protection device in which a plurality of pilot burner flames are each associated with one or more thermocouple elements controlling in turn separate first relays in such a way that, when in operation, if any one pilot flame is not burning an ignition process is started and a main gas valve is closed.
One advantage of the present invention is that the individual ignition burners are ready for operation at the same or nearly the same time. With the switching on of the main current a single pilot gas valve opens immediately and gas is thereby released for all the pilot burners. Also all the ignition devices already receive ignition current. The result is that all the thermoelements build up a thermocurrent substantially simultaneouslyf This is accomplished in a time interval in which only one of the ignition or pilot burners of prior art safety devices is ready for operation. Prior art devices have switching valves foreign to the object of the application. These switching valves have to be operated manually and in a predetermined sequence. In another known safety device, it is necessary to wait until the thermorelay or thermorelays have shifted over before the manual push button of the' switching valve can be released. An inventive feature of the object of the application lies therefore especially in that, in an extremely short time, the thermoelectrically controlled ignition safety device is brought into the operating state and in the fact that the device requires only one pilot burner valve though there be a plurality of pilot lights.
In order that the invention may be more clearly understood, one embodiment will now be described, by way of example, with reference to the accompanying drawing 3,185,203 Patented May 25, 1965 "Ice which schematically shows an embodiment in its operating condition.
The drawing shows three separate main burners 213, 20, 2G", lighted and monitored each by its pilot burner 13, 13', 13". The number of main burners and ignition points can of course be varied at will. In the gas supply to the main burners 20, 211, 20", is an electromagnetic main gas valve 18, before which is a gas supply branch 44 to a pilot gas valve 14. From pilot gas valve 14 pilot supply branches 44", 44", 44, lead to pilot burners 13, 13, 13". At each pilot burner 13, 13', 13", is an ignition electrode 12, 12, 12", and a thermocouple element 15, 15', 15". The ignition electrodes 12, 12', 12" are wired in parallel in the secondary circuit of ignition transformer 11. Pilot gas valve 14 is directly and electrically operated by a monitoring relay 30', arranged in the main body of the device as shown in the upper part of the drawing.
The thermoelectric current from thermocouple 15 at pilot burner 13 operates thermoelectric relay The thermoelectric current from thermocouple 15' at pilot burner 13'. operates thermoelectric relay 70 and the thermoelectric current from thermocouple 15" at pilot burner 13" operates thermoelectric relay 10'. Each of the thermoelectric relays 70 and 70' has two sets of contacts 72-73, 76-77 and 74-75, 78-79 respectively. The thermoelectric relay 10 however has three contact pairs 8-9, 16-17, and 8-9'. The sets of contacts 8-9, 76-77 and 78-79, of thermoelectric relays 10, 70, 70, are wired in parallel in the cir'cuit'of ignition transformer 11. The sets of contacts 16-17, 72-73 and 74-75, of thermoelectric relays 10, 719, 70', are however wired in series in the circuit of main gas valve 18. g
The monitoring relay 36 has three contact pairs 31-32, 33-34, and 35-36. The self-holding contacts 33-34-013 monitoring relay 30' are connected as follows: 33 besides being connected to contact 35 to be described later is also connected by a lead to contact 9' of thermoelectric relay 10', while 34 is connected by a lead to contact 8' of thermoelectric relay 10', A mains switch 1, a set of contacts 5-6 of a thermal cut-oft 7, and the set of contacts 31-32 of monitoring relay 30' lie with the contacts 16-17, 72-73, and 74-75, of thermoelectric relays 10', 70 and 70, in series in the operating circuit of main gas valve 18.
The third set of contacts 35-36 of monitoring relay 30' is in circuit from thermal cut-off 7 to a tapping 37 on the primary winding of ignition transformer 11. The actuating coil of monitoring relay 30' is fed from the output of rectifier 56, one junction of which is connected,
through contacts 26 of pressure switch 27 connected to gas supply 43, and contacts 2-3 of thermostat 4, to con.- tact 34 of monitoring relay 30', and the other junction to contact 80f the thermoelectric relay 10'.
The primary winding of ignition transformer 11 is connected at one end by a lead to contact 32 of monitoring relay 3%, and at the other end to contact 9 of thermoelectric relay 10', whose opposite contact 8 is connected to the mains supply.
The operation of the device is as follows:
On closing mains switch Llmains voltage is applied to contacts -6 of thermal cut-off 7 and simultaneously via its exciter coil (not shown in detail), contacts 35, 33 of monitoring relay 30, contacts 8'-9' of thermoelectric relay 10', contact 34 of monitoring relay 30', the closed contacts 3-2 of thermostat 4 and closed contacts 26 of pressure switch 27, to one point of rectifier 56; The oppo site point of rectifier 56 is connected via contact 8 of thermoelectric relay 10 directly to the other mains lead, Consequently, the coil or the monitoring relay in circuit with the direct current output from the rectifier is excited, and its three contact sets 31-32 33-34 and 35-36, are closed. Thereby, the circuits of ignition transformer 11, pilot gas valve 14 and thermal cut-oh 7 are closed.
The circuit of ignition transformer 11 extends via contact 6 of thermal cut-off 7, the now closed contact set 31- 32 of monitoring relay 39', through the primary winding to the other side of the mains supply via the still closed contact set 9-8 of thermoelectric relaylfl'. The current induced in the secondary winding of ignition transformer 11 produces a stream of ignition sparks between ignition electrodes 12, 12', 12", and pilot burners 13, 13' and 13" respectively. p t
The circuit for pilot gas valve 14 and its actuating coil goes similarly from contact 32 of monitoring relay 30' and returns via contact 8 of thermoelectric relay 10" directly to the other mains lead. The pilot gas valve 14, thus excited, opens and the gas flowing to pilot bur nerst 13,
13', and 13" is ignited by the sparks from electrodes 12,
12', and 12" (see the preceding paragraph).
The circuit for the exciter coil of thermal cut-oh? 7 goes via contact pairs 35-36 of monitoring relay 30- to tapping 37 of the primary winding of ignition transformer 11. This ensures that the current branched from thermal 'cut-oif 7 can be cut off after a predetermined time. The pilot flames ignited as previously described at. pilot burners 13,13, 13", heat their associated thermocouples or thermocouple batteries 15, 15', 155'. The thermoelectric currents so produced excite thermoelectric relays 7t), 70 and 10', on which the hitherto closed contacts 78-79, 76-77, and 8-9, are opened and the hitherto open contacts 74-75, 72-73, and 16-17 are closed.
The ignition process continues and the main gas valve stays shut until all thermoelectric relays 10, 70, and 70 have switched over, since the one set of contacts 8-9, 76-77, and 78-79, are in parallel in the primary circuit of ignition transformer 11 and the other set of contacts 16-17, 72-73, and 74-75, are however in series with main gas valve 18. On switching oh? the ignition transformer 11, the tapping 37 of its primary winding ceases to supply current. There then flows through thermal cut-off 7 only a small residual current via contact 35, the self-holding contacts 33-34 of monitoring relay 30', contacts 3-2 of thermostat 4, contacts 26 of pressure switch 27, through the rectifier 56 and contact 8to the mains. This residual current flowing through thermal cut-off 7 is'not however large enough to cause it to cut off. It may be noted that monitoring relay 30' will notrespond if the exciter coil of thermal cut-oft is interrupted, since the exciter coil of the relay depends for its excitation on the current through that of the thermal cut-off. v
On excitation of thermoelectric relay 10' however its contacts 8-9' are also opened. The circuit of the exciter coil of monitoring relay 30 however continues to receive current via self-holding contacts 33-34 as described in the preceding paragraph. On any brief interruption of mains current, as by switching off the mains switch 1, thermostat 4, pressure switch 27, or the like, the monitoring relay 30' cuts off at once, and switches on againafter removal of the source of difliculty-only when thermoelectric relay 10' has returned to its starting position and among other things the contacts are closed. 7
If for any reason any of the thermoelectric currents should fail, the thermoelectric relay associated with" it switches back and immediately shuts main gas valve 18. But by switching back, the thermoelectric relay initiates the ignition process for all pilot burners. At the same time a current flows also through tapping 37 of the primary Windingof ignition transformer 11, and the exciter coil of thermal cu-t-ofi 7, which causes the cut-off to operate it the current lasts longer than the prescribed cut-off period.
If. there is still no thermoelectric current from the defective thermocouple, then the thermal cut-off responds and opens its contacts 5-6. The whole protection device then shuts off. After removal of the source of difi'iculty, the thermal cut-01f can be-re-set by hand and the whole protection device be put into operation as already described,
1. In an automatic protection device adapted to be connected to electric mains and for a plurality of main gas burners each having a pilot gas burner with electrically operated ignition means, electrically operated main gas valve means to control the flow of gas to the main burners, electrically operated pilot gas valve means to control the flow of gas to the pilot burners, and burner operation sensing means associated with each pilot burner, the improvement comprising: a thermoelectric relay for each pilot burner, each relay including an actuating coil, a normally opened contact and a normally closed contact, each coil being connected to the respective sensing means to be energized upon the respective sensing means being heated by the respective pilot burner; monitor relay means including an actuating coil and normally opened contact means; and circuit means including switch means connected to said monitor relay means and adapted to be connected to the mains to energize the monitor relay coil when the switch means is closed, said normally closed contacts ofeach thermoelectric relay being connected in parallel with each other and in series with said ignition 1 means and with said normally opened contact means of any one of the normally closed contacts. is closed, said normally opened contacts of the thermoelectric relays being connected .in series with each other and in series with said main valve means and with said normally opened contact means of said monitor relay means to open said main valve means only when said monitor relay means and all of said thermoelectric relays are energized; said pilot valve means being connected to said normally opened contact means of the monitor relay means to be energized when the monitor relay means is energized.
2. In an automatic'protection apparatus adapted to be connected to electric mains and for use with a plurality of main gas burners each having a pilot gas burner with electrically operated ignition means, electrically operated main gas valve means to control the how of gas to the main burners, and electrically operated pilot gas valve means to control the how of gas to the pilot burners, the lmprovement comprising: a safety control device for each of the pilot burners, each device comprising a relay having an actuating coil, normally opened contacts and normally closed contacts, and heat responsive means 'connecting said normally closed contacts in parallel and connecting-said ignition means to the mains to energize the ignition means when any one of the normally closed contacts is closed; and circuit means connecting said normally opened contacts in series and in series'with the main gas valve means to open the main gas valve means only when all of said relays are energized.
3. In an apparatus as set forth in claim 2, including circuit means connecting the pilot valve means to the mains through the normally opened contact of the monitor relay to open the pilot valve means to deliver gas to the pilot burner when the monitor relay is energized.
References Cited by the Examiner UNITED STATES PATENTS 2,212,352 8/40 Plein 158-28 10 JAMES W. WESTHAVER, Primary Examiner.
MEYER PERLIN, Examiner.