US2120053A - Apparatus for shutting off fuel supply to a furnace or the like - Google Patents

Description

June 7, 1938. D. w. FEHR/ENBACH APPARATUS FOR SHUTTING-OFF FUEL SUPPLY TO A FURNACE OR THE LIKE Filed June 26, 1936 2 Shepts-Sheet l ATTORNFY D. W. FEHRENBACH June 7, 1938.

APPARATUS FOR SHUTTING-OFF FUEL: SUPPLY TO A FURNACE OR THE LIKE Filed June 26, 1936 2 Sheets-Sheet 2 INVENTOR Dm/e W fZfirenbac/z ATTORNEY Patented June 7, 1938 PATENT OFFICE APPARATUS FOR SHUTTING OFF FUEL SUP- PLY TO A FURNACE OR THE LIKE Daniel William Fehrenbach, Kansas City, Mo.,

assignor to Kansas City Journal-Post Company, Kansas City, Mo., a corporation of Missouri Application June 26, 1936, Serial No. 87,452

4 Claims.

This invention relates to an apparatus for shutting off the fuel supply to a furnace or the like, particularly to those operating on liquid or gaseous fuels of explosive character. In furnaces of this type the flame for various reasons often becomes extinguished with the result that the fuel continues to flow and soon fills the combustion chamber with a highly explosive mixture. The fuel is, therefore not only wasted but the combustible mixture is apt to cause a serious explosion particularly if attempt is made to relight the fuel before the combustion chamber has time to be scavenged.

Other important objects of the invention are to provide an apparatus of this character which may' be operated remotely from the place of shutting off the fuel; to provide for shutting off the fuel in case the burner is not operating efiiciently; to prevent admission of fuel to the combustion chamber when the furnace door is open; and to provide signals for indicating when the burner is operating satisfactorily, when the burner is out of operation, and when the fuel supply has been turned on preparatory to lighting the burner.

It is also an important object of the invention to prevent functioning of the shut-off mechanism when the burner is operating with a low flame that has been purposely set to maintain lower furnace temperatures, but which will cause function of the shut-off in case the flame should become extinguished.

In accomplishing these and other objects of the invention, as hereinafter pointed out, I have provided improved details of structure, the preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig. 1 is a sectional perspective view of a part of a furnace combustion chamber having a burner supplied with a liquid or gaseous fuel and equipped with a shut-off mechanism and control apparatus embodying the features of the present invention.

Fig. 2 is a diagrammatic view of a control system used in connection with a battery of furnaces.

Fig. 3 is a detail perspective view of the shutoff valve and trip mechanism therefor.

Fig. 4 is a cross-section on the line 4-4 of Fig. 3.

Referring more in detail to the drawings:

I designates a conventional type furnace having a combustion chamber 2 equipped with a burner 3 adapted for burning a liquid or gaseous fuel, The burner 3 is mounted in an opening 4 in the front wall of the furnace and is supplied through a pipe line Shaving a manually operated control valve 6. In the case of a liquid fuel, such as heavy oils, the burner is provided with a steam connection I for effecting vaporization of the fuel as in conventional practice. Located in the front wall of the furnace at a point above the burner is a fire-door 8 through which access is had to the burner in the combustion chamber.

The construction thus far described is conventional to apparatus of this character and specifically forms no part of the present invention, which provides means for automatically shutting off the fuel supply in case the flame 9 from the burner should become extinguished.

In carrying out the present invention, the supply line 5 is provided with a pressure operated switch Ill including a diaphragm housing ll having a diaphragm l2 that is responsive to pressure of the fuel moving through the line. The diaphragm l2 operates a rod l3 that extends through a suitable packing gland ll in the top of the housing II to connect with a switch l5. The supply line is also provided with an automatic shut-off valve I6 having a reciprocatory actuating stem ii that is connected with a suitable trip mechanism generally designated I 3. The trip mechanism I8 is best illustrated in Fig. 3 and includes a base l9 that is supported on the pipe 5 at a point adjacent the valve by means of U-clamps and 2| extending thereunder and having their shanks 22 projecting through suitable openings in the base for mounting nuts 23 whereby the base is clamped to the pipe and retained in horizontal position.

Projecting upwardly from the base, at the end adjacent the valve I6, is a bracket 24 having spaced ears 25 to mount a fulcrum pin 25 on which a rock lever 21 is pivotally mounted. The rock lever has one end projecting over the stem I1 and is pivotally connected therewith by means of a cross pin 28 extending through depending cars 29 on the lever and through a head 3. 0n the stem. The lever extends beyond the valve and carries a weight 3i whereby the valve is normally retained in closed position to shut off flow through the line. The opposite end of the lever extends through the forked end 32 of a guide bracket 33 and carries a cross bar 34 extending therethrough and having its ends 35 and 36 arranged for latched engagement with latches 3'! and 33 pivotally mounted on the sides of the base, as shown at 39.

The free ends of the latches terminate in books 40 having rounded upper ends 4| for guiding the bar 34 into latched engagement with the hooks when the valve stem I1 is moved to position for opening the valve. The latches 31 are normally retained in latching position relatively to the bar 34 by suitable springs 42 having one of their ends engaging the base and their other ends engaging against the respective latches.

Carried on the bracket 33, and projecting between the latches 31, is a magnet 44 having a winding 45 and a metallic core 46 adapted to attract an armature 41 when the coil is energized, as later described. The armature 41 has its lower end 48 pivotally mounted in a recess 49 of the base on a pin 58. The upper end of the armature terminates in a gooseneck bend and carries a cross pin 5| having its ends normally engaging the latches 31 and 38 incidental to the overbalancing weight thereof in the direction of the magnet.

Supported on the base, intermediate the brackets 24 and 33, is an insulator 53 carrying spaced pairs-of contacts 54-55 and 56-51 adapted to be respectively engaged by circuit closing plates 58 and 59 loosely carried on headed pins 68 and 6| depending from an insulating block 62 on the under side of the lever 21. When the valve is open and the rock lever is in latched position, the plates 58 and 59 are yieldingly held in engagement with the pairs of contacts by coil springs 63 and 64 having their ends engaged against the insulating block 62 and against the contact plates respectively. ,The pins are of such length that when the valve is closed the heads 65 of the pins will carry the contact plates away from engagement with the pairs of contacts to break circuit therethrough as later described.

Formed in the front wall of the furnace, at a point above the fire-door 8, is a recess 66 for a phototube holder 61 to which access is had through a door 68 covering the recess 68. The holder carries a phototube 69 located in focusing alignment with a tube 18 extending downwardly through the furnace wall and at such an angle that the axis thereof intersects the flame 9 at its hottest point, as indicated by the dotted line H, so that the tube is rendered active incidental to the intensity of the flame. The circuit wires for the tube are indicated at 12 and extend from the housing 61 through a conduit 13 having connection with a photoelectric relay 14 that is of any standard design but which includes a relay switch 15, an amplifying tube 16, and a transformer 11 that is adapted to convert a current from a supply line 18 to that suitable for operating the relay. The switch 15 includes fixed and movable contacts 19 and 88 that are normally closed when the fire is burning properly and which are ordinarily opened in response to control by the phototube when the fire becomes extinguished. The contacts 19 and 88 are respectively connected with terminals 8| and 82 for connection of the relay with the valve operating circuit now to be described.

83 and 84 designate the respective line wires of a suitable current supply for furnishing current to actuate the valve shut-off part of the circuit as well as the signal circuits whereby the conditions of operation are visibly indicated at a point remote from the shut-oil valve I6.

The line 84 connects with a conductor 85 leading to the arm 86 of a switch that is caused to engage a fixed contact 81 when the fire-door 8 is closed to pass current through a conductor 88 leading to the terminal 8| of the relay switch 15. The other terminal 82 is connected by a conductor 89 leading to one of the contacts of the switch I5. The other contact of the switch I! is connected by a conductor 98 with one of the leads 9| of the winding 92 for a solenoid switch 93. The other lead 94 of the solenoid winding is connected by a conductor 95 with the other line wire 83, thus completing circuit through the switch on the fire-door through the photoelectric relay switch 15, through the pressure actuated switch I 5 and the winding of the magnetic switch 93. when the burner is operating.

The switch 93 includes an armature 86 that is normally influenced by the solenoid winding 92 against action of a spring 91 to normally close circuit to the pairs of contacts 56 and 51, previously described, the armature of the switch also being connected with the conductor 95. The contact 98, with which the armature is retained in engagement upon energization of the solenoid coil, is connected by a conductor 98 with the contact 56. The other contact 51 is connected by a conductor I88 with one end of a solenoid winding I8I of a second magnetically operated switch I82, the other end of which is connected by a conductor I83 with the conductor 88. It is thus obvious that when the switch I5 and the contacts 86 and 81 are closed current flows through the conductor 95, switch arm 93, contact 98, conductor 99, switch contacts 56 and 51, conductor I88, solenoid winding I 8|, conductor I83, conductor 88, switch contacts 81 and 86 and conductor 85v thereby energizing the magnetic switches 93 and I82.

The switch I82 includes an armature I84 engageable with a contact I85 when the solenoid winding IN is energized. The contact I85 is connected to the contact 54 by a conductor I86 and the other contact 55 is connected by a conductor I81 with one of the terminals of the solenoid 45. The other terminal of the solenoid is connected by a conductor I88 with a second contact I89 of the relay switch 93 that is adapted to be engaged by the armature 96 thereof when the spring 91 becomes effective in opening the circuit between the switch arm and the contact 98. The armature 96 is connected with the conductor 99 by means of a resistance I I8 for a purpose later described.

Connected in the conductors 98 and I88 are signal lights III and H2 respectively, which are preferably green in color. Red and amber signal lights II 3 and II 4 are connected in series by a conductor II5 with the conductors I88 and I86. The conductor I I5 is connected with a contact II6 for the switch I82 corresponding to the contact I89 of the switch 93. The armature I84 of the switch I82 is normally retained in engagement with the contact II 6 by a spring II1 when the solenoid winding I 81 thereof isdeenergized. In order to effect manual closure of the circuit to the solenoid 45 a normally opened switch H8 is connected across conductors 95 and SI.

With an apparatus constructed and assembled as thus far described, the furnace is set in operation as follows:

The valve 6 is first opened and then the valve I6 by lifting the weighted end of the rock lever 21 so that the hooked end of the latches 31 and 38 engage over the ends of the cross bar 34 to normally hold the valve I6 in open position. Since the burner has not yet been ignited the photoelectric relay switch will, of course, be open, consequently no current can flow through the coil 92 and the spring 91 will retain the armature in engagement with the contact I89 so that there is a current flowing through the coil 45, contacts 54 and'55, conductor I86, lamp I I4, contact II. and conductors I08, 08 and 05, but due to the fact that the resistance of the lamp H4 is of high value and in series with the coil 45 there is not enough current flowing through the coil to effect unlatching of the lever 21. Also since the resistance III is in series with the col] ill suilicient current cannot flow therethrough to cause movement of the armature away from the contact II5. Since the contact I09 is engaged by the armature 88, current will flow through the signals H3 and H4, the red signal III indicating that the burner is out of operation and the amber signal II4 that the fuel is turned on and ready to be lighted. I

When the door 8 is opened to light the burner it will, of course, be necessary to hold the valve I 5 open for the reason that opening of the door breaks the circuit through the switch 88. However, when the switch is again closed, the circult is reestablished and the valve I5 will be kept open.

After lighting the b er, the phototube is eflectlve to cause closing of the relay contacts I9 and so that current can then flow from the line wire 88, conductor 95, solenoid winding 92, signal light III, conductor 90, switch I5, conductor 89, contacts I9 and 80,,conductor 88, switch contacts 81 85, conductor 85, back to the line 84, thereby energizing coil 92 and causing the armature 98 to be drawn into engagement with the contact 88. Current then flows from the line 83, conductor 95, armature 98, contact 98, conductor 99, contacts 58 and 51, conductor I00, signal light II2, solenoid IOI, conductor I83, conductor '8, switch contacts 81 and 88 and conductor 85. The green light III is now illuminated to indicate that the burner is in operation. When the electrical circuit through the contact I89 is broken the red signal light III is extinguished and current is broken through the solenoid 45. Since the resistance H0 is now out of circuit suflicient current flows to the coil IOI to break the circuit through the amber signal light H4 and to establish a direct circuit through the trip magnet 44 by way of the contact I05, but no current will flow therethrough since the circuit to the contact I09 has been opened.

Now, assuming that the flame should become extinguished for some reason, the phototube will become effective in breaking the relay circuit through the contacts I9 and 80; When this occurs circuit is broken through the coil 92 so that the spring 91 comes into action to break contact of the armature with the contact 98 and establish engagement with the contact I09.

When this occurs current will flow from the line wire 83 through the conductor 95, armature 95, contact I09, conductor I08, solenoid 45, conductor IIII, contacts 54 and 55, conductor I08, contact I05, armature I04, conductor I03, conductors 88 and 85 back to the line wire 84 thereby energizing the coil 45 to efiect unlatching of the lever arm whereupon the lever is free to tilt under influence of the weght 3i to close the valve I5, thereby shutting off flow of fuel to the burner. Attention is here directed to the fact that the current flowing to the magnet when the resistance IIII is in series is such as to hold the armature I04 in contact with I05 thereby maintaining the circuit through the magnet 44 closed; however, the current is not suflicient to close the circuit after it has beenopen as in the instance above noted when the valve I6 is initially opened preparatory to lighting of the burner.

When current is established through the coil to indicate that the burner is out of service. Immediately upon tilting of the lever the circuits through the pairs of contacts 58-51 and 54-55 are broken to interrupt current flow through the coil III. When this occurs the spring III comes into play to cause the armature I04 to engage the contact II8 so that the red light is kept in circuit but all of the other signal lights are extinguished. The system may then be put back in service by opening the valve I8 and lighting the burner 3 as above described. Should pressure drop in the supply line the diaphragm will cause opening of the switch II to break circuit through the magnet winding 92 and cause shutting of the valve in the same manner as if the relay operated responsive to the phototube. If the burner is not operating efllciently, or should the flame not maintain the intensity to which the phototube has been adjusted, then the phototube will again come into play to shut off the supply of fuel to the burner in the same manner as ifthe flame were extinguished. Openr'ng of the door 8 will also effect breaking of the circuit through the contacts 88 and 81 to shut oil flow of oil to the burner. Attention is directed to the fact that the oil supply to the burner may also be shut ofi manually at a remote point by closing the switch II8 which shorts the current to the coil 92 so it becomes deenergized and allows the armature of the switch 93 to move into position for establishing circuit through the coil 45, which then operates to shut off the valve I5 in the same manner as described in connection w'th its operation incidental to actuation of the phototube.

At times it may be desirable to operate the burner with a low flame and in such cases the flame does not operate with the same intensity but tends to flicker which would cause the phototube to effect shutting oil the fuel supply when it is not desired. In order toovercome this difliculty and yet provide for shutoil of the fuel supply in case the flame should become extinguished, I provide an automatic switch I adapted to keep the circuit which includes the contacts I9 and 80 closed when the photocell relay is opened under flickering tendency of the flame.

The swFtch I20 includes a pair of fixed contacts I2! and I22 that are respectively connected by conductors I23 and I24 with the conductors 89 and 88. The contacts are normally closed by a bridging contact I25 carried on a lever I25 that is pivotally mounted on a bracket I2I carried by a base I28. The other end of the lever is connected with a piston I29 operable in a dash-pot I30 whereby movement of the lever I28 is retarded. The bridging contact is normally retained in engagement with the fixed contacts I2I and I22 by means of a spring I3I connected with the lever and with the base I28. It is thus obvious that as long as the bridging contact is engaged with the contacts I2I and I22 the relay switch I5 is normally out of circuit and has no effect upon the coil 92.

In order to make the relay switch I5 effective in case the flame should become extinguished, it is provided with a second fixed contact I32 connected with a terminal I33 to which a conductor I34 is connected for supplying current to a solenoid I35 having its other end connected by a conductor I36 with the conductor 85, the solenoid I35 being effective to break circuit through the contacts I2I and I22 under regulating control of the dashpot I30. In order that the solenoid .45, current also flows through the red light III,

-' bridging contact I25 even though the switch arm of the relay momentarily engages the contact I32 to cause current to flow through the coil I35, for the reason that the dash-pot prevents the coil from being immediately effective in break ing circuit through the contacts I2I and I22.

Therefore, before the circuit can be broken, the phototube has again closed circuit through the photocell relay; however, should the flame become extinguished the relay switch arm retains engagement with the contact I32 to energize the coil a sufllcient length of time to effect breaking of the circuit through the contacts I2I and I22 to effect shutting of the valve I 8 and stopping flow of fuel to the burner. When the furnace is operating under normal conditions the switch mechanism I is taken out of the circuit upon opening of a switch I31 in the conductor I84.

In Fig. 2 is shown a wiring diagram of my improved circuits connected with a battery of two furnaces, each having a photocell circuit, designated I38 and. I39 respectively, that are connected in parallel with the circuit to the solenoid winding 92.

In this instance the fire-door switches I40 and I are connected by a conductor I42 having a branch conductor I 43 connected with a manually operated switch I44 which is connected by a conductor I45 to the relay terminal III as is conductor 88 in Fig. 1, for making the relay switch I38 effective. The relay circuit I39 is made effective independently of the relay circuit I38 upon closing a switch I46 that is connected between the conductors I41 and I48 respectiveiy, corresponding to the conductor 89 of the circuit illustrated in Fig. 1. The relay circuit I38 is also connected to the conductor I41 and to the conductor I42 by a conductor I49. The relay circuits are both made effective by wiring them in series by connecting them with a conductor I45 to a switch I50 which is in turn connected to the conductor I41. When it is desired to make the circuit I38 effective exclusive of the circuit I38, the switch I44 is closed and the switches I46 and I58 opened. When it is desired to operate the relay I39 exclusive of I38, then the switches I44 and I58 are opened and the switch I46 is closed. Both relay circuits can be made effective by closing the switch I50 and opening switches I44 and I46 so that either relay circuit can operate the shut-ofi mechanism.

From the foregoing, it is obvious that I have provided an automatic apparatus that will function responsive upon failure of the combustion of the fuel in the fire-box so that the fuel is automatically shut off the instant that the failure occurs, thereby preventing the fire-box from filling with explosive gases and oil. The signals also advise the operator of the conditions occurring both at the time the supply to the burner is shut off and when the burner is being put back into service.

What I claim and desire to secure by Letters Patent is:

1. In combination with a furnace having a burner, a door for access to the burner and meansfor supplying fuel to the burner of means for controlling said fuel supply, including a valve, a magnet for closing the valve, an electrical circuit for energizing the magnet, a magnetic switch in the magnet circuit, a relay circuit connected with the magnetic switch, means responsive to presence of combustion in the furnace for closing the relay circuit to energize the magnetic switch for opening the magnet circuit and operable upon absence of combustion to open the relay circuit and effect closure of the magnetic switch for closing the valve, and a switch in said magnet circuit having connection with the door for breaking said magnet circuit to permit closing the valve upon opening the door.

2. In combination with a furnace having a burner and means for supplying fuel to the burner of means for controlling said fuel supply including a valve, a magnet for closing the valve, an electrical circuit for energizing the magnet, a magnetic switch in the magnet circuit, a relay circuit connected with the magnetic switch, means responsive to presence of combustion in the furnace for closing the relay circuit to energize the magnetic switch for opening the magnet circuit and operable upon absence of combustion to open the relay circuit and effect closure of the magnetic switch for closing the valve, 8. signal circuit connected with the magnet circuit and energized upon closure of the magnetic switch to indicate closing of the valve, a second magnetic switch in the magnet circuit for controlling the signal circuit, a second circuit connected with the first named magnetic switch for energizing the second magnetic switch, and a switch in said second circuit and having connection with the valve for closing saidcircuit to energize the second magnetic switch for opening the signal circuit when the valve is opened.

3. In combination with a furnace having a burner and means for supplying fuel to the burner of means for controlling said fuel supply including a valve, a magnet for closing the valve, an electrical circuit for energizing the magnet, a magnetic switch in the magnet circuit, a relay circuit connected with the magnetic switch, means responsive to presence of combustion in the furnace for closing the relay circuit to energize the magnetic switch for opening the magnet circuit and operable upon absence of combustion to open the relay circuit and effect closure of the magnetic switch for closing the valve, a signal circuit connected with the magnet circuit and energized upon closure of the magnetic switch to indicate closing of the valve, a second magnetic switch in the magnet circuit for controlling the signal circuit, a second circuit connected with the first named magnetic switch for energizing the second magnetic switch, a switch in said second circuit and having connection with the valve for closing said circuit to energize the second magnetic switch to open the signal circuit when the valve is opened, a signal circuit controlled by the second magnetic switch for indicating open position of the valve, and a switch in the magnet circuit and having connection with the valve to close the last named signal circuit.

4. In combination with a furnace having a burner and means for supplying fuel to the burner of means for controlling said fuel supply including a valve, a magnet for closing the valve, an electrical circuit for energizing the magnet, a magnetic switch in the magnet circuit, a relay circuit connected with the magnetic switch, means responsive to presence of combustion in the furnace for closing the relay circuit to energize the magnetic switch for opening the magnet circuit and operable upon absence of combustion to open the relay circuit and effect closure of the magnetic switch for closing the valve, a signal circuit connected with the magnet circuit and energized upon closure of the magnetic switch to indicate closing of the valve, a second magnetic switch in the magnet circuit for controlling the signal circuit, a second circuit connected with the first named magnetic switch for energizing the second magnetic switch, a switch in said second circuit and having connection with the valve for closing said circuit to energize the second magnetic switch for opening the signal circuit when the valve is opened, a signal circuit controlled by the second magnetic switch for indicating open position of the valve, a switch in the magnet circuit and having connection with the valve to close the last named signal circuit, and a resistance in said second circuit including a resistance bypassing the first named magnetic switch to prevent deenergization of said second magnetic switch when the relay circuit is broken and until the circuit through the second magnetic switch is opened by way of the switch in the second circuit.

DANIEL WILLIAM FEHRENBACH.

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