US3453062A

US3453062A - Control system for burner apparatus

Info

Publication number: US3453062A
Application number: US647438A
Authority: US
Inventors: Wilbur F Jackson; Jay R Katchka; Donald Mcallister
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1967-06-20
Filing date: 1967-06-20
Publication date: 1969-07-01
Anticipated expiration: 1986-07-01

Description

y 1969 w.'F. JACKSON ETAL 3,453,062

CONTROL SYSTEM FOR BURNER APPARATUS Filed June 20, 1967 95 2o :-E:. l 86 44 94 66 64 45 62 I 42 93 92 I Q Q Z5 Kg I 9 ,l8 J zo? Q.

FIGIv INVENTOR WILBUR F. JACKSON, JAY R. KATCHKA 8 DONALD MC ALLISTER ATTORNEY United States Patent 3,453,062 CONTROL SYSTEM FOR BURNER APPARATUS Wilbur F. Jackson, Rolling Hills, Jay R. Katchka, Long Beach, and Donald McAllister, Palos Verdes Estates, Calif., assignors to Robertshaw Controls Company,

Richmond, Va., a corporation of Delaware Filed June 20, 1967, Ser. No. 647,438 Int. Cl. F23q 9/08; F16k 31/12 US. Cl. 431-58 9 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a control system for burner apparatus and, more particularly, a system for controlling and regulating main and pilot flows of fuel to burner apparatus having a main burner and a pilot burner in igniting proximity thereto.

In control systems for burner apparatus, it has become standard practice to control thermostatically and to regulate the pressure of a fuel flow to the burner apparatus. These systems generally utilize a differential pressure operated diaphragm for effecting valve movement that varies the fuel flow to the burner apparatus and the differential pressure for operating the diaphragm is provided by means of a bleed flow. However, the numerous controls associated with the bleed flow in such systems have resulted in complex arrangements requiring complicated components.

It is, therefore, an object of the present invention to control and regulate the pressure of fuel flow to burner apparatus by a relatively simple system having relatively few control components.

The present invention has another object in that a bleed flow line for operating the main diaphragm valve means of a burner control system, is supplied from a pressure regulated pilot flow line.

This invention has another object in that the bleed flow line for operating the main diaphragm valve means of a burner control system is subject to manual on-olf control.

It is another object of this invention to insure closure of the main diaphragm valve means of a burner control system by its bleed flow line so that safe lighting may be accomplished at the pilot burner.

A further object of the present invention is to incorporate the diaphragm operated valve means of a burner control system in the manual on-oif valve for such systems.

A still further object of this invention is to provide the manual on-olf valve of a burner control system with bleed flow porting for controlling the bleed flow that operatesthe main diaphragm valve means in such system.

In practicing the present invention, a control system for main and pilot burner apparatus is provided with a casing having inlet means adapted for connection to a source of fuel and having main outlet means adapted for connection to the main burner and pilot outlet means adapted for connection to the pilot burner, main valve means disposed between the inlet and main outlet means for controlling a flow of fuel to the main burner, diaphragm means for moving the valve means and defining an operating pressure chamber in the casing, pilot flow means communicating with the inlet means to supply a pilot flow of fuel to the pilot burner, bleed flow means having one end communicating with the pilot flow means and another end communicating with the outlet means and having branch bleed flow means intermediate its ends communicating with the operating pressure chamber, control means in the bleed flow means for controlling a bleed flow of fuel to the operating pressure chamber and effecting operation of the diaphragm means to move the valve means, and pressure regulating means in the pilot flow means upstream of the bleed flow means for regulating the pressure of the pilot flow of fuel to the pilot burner and the bleed flow of fuel to the operating pressure chamber.

Other objects and advantages of the present invention will become apparent from the following description of a preferred embodiment, taken in conjunction with the accompanying drawing wherein:

FIG. 1 is a schematic diagram of a control system for burner apparatus with the control device shown in cross section;

FIG. 2 is a partial top plan view showing the on position of parts of FIG. 1;

FIG. 3 is a partial cross section of FIG. 1 with parts shown in an off position;

FIG. 4 is a top plan view of FIG. 3;

FIG. 5 is a partial cross section similar to FIG. 3 with parts shown in a pilot position; and

FIG. 6 is a top plan view of FIG. 5.

As is illustrated in FIG. 1, the present invention is embodied in a control device including a casing, indicated generally at 10, having an inlet port 12 for receiving fuel from a gas source (not shown), a main flow outlet port 14 connected to a main burner 16, and a pilot flow outlet port 18 connected to a pilot burner 20. A fuel flow between the

ports

12 and 14 passes through a valve seat 22 which is controlled by a main valve member 24 in the form of a disc intermediately mounted between the ends of a shaft which is thus divided into a guide stem 26 and a valve stem 28. The free end of the valve stem 28 is engaged by the rigid center of a main diaphragm 30 that is peripherally clamped between sections of the easing 10 wherein the diaphragm 30 defines the movable wall between an operating pressure chamber 32 and an outlet pressure chamber 34.

Surrounding the valve seat 22 and in axial alignment therewith, a frusto-conical bore 36 in the casing 10 intersects the passage defining the inlet port 12. A manually operated, tapered plug valve 38 is rotatably seated in the bore 36 and biased therein by a coil spring 40 mounted in compression between the large end of the plug valve 38 and an internal wall of the casing 10. A plug valve stem 42 centrally extends from the large end of the plug valve 38 through a suitable bore in the casing 10 and a manually operable knob 44, which has a notch 45 at its pilot position, is keyed to the exterior of stem 42 by any suitable me-ans (not shown).

The bottom wall of plug valve 38 is hollowed out to define a chamber 46, the inlet of which is defined by a transverse opening 48 in the conical wall of the plug valve 38 so as to register with the inlet passage 12. The main valve seat 22 defines the outlet for the chamber 46, and a centrally bored boss 50 on the plug valve body extends about half way into the chamber 46 to receive the guide stem 26; a coil spring 52 surrounds the boss 50 and stem 26 and is mounted in compression between the plug valve body and the valve disc 24 to bias the same toward the valve seat 22.

Radially spaced from the inlet opening 48, the conical wall of the plug valve 38 is slotted at 54 for a purpose to be described hereinafter. Spaced slightly above the inlet opening 48, a smaller transverse opening or passage 56 extends in the form of a peripheral slot on the outside conical surface of the plug valve 38; the passage 56 is alignable with a pilot flow conduit 58 in the casing to permit a pilot fiow of fuel to conduit 58 in any position of the plug valve 38 between its pilot and on positions. The pilot flow conduit 58 leads to a cavity having a filter 60 therein and thence to a pilot flow pressure regulator 62 having a atmospheric vented chamber 64 and an outlet pressure chamber 66 separated by a flexible rubber diaphragm 68. A pressure regulating valve 70 extends from the bottom surface of the diaphragm 68, the upper surface of which is biased by a coil spring 72 mounted in compression between a back-up plate (not shown) on the diaphragm 68 and an adjustable plug 74 threaded into a suitable opening in the regulator 62.

Downstream of the regulating valve 70, the outlet pressure chamber 66 communicates with a safety valve chamber 76 which is controlled by the valve 78 of an electromagnetic holding device 80 of any conventional type. As is well known in the art, the electromagnetic holding device 80 includes an electromagnet which holds the valve member 78 in an open position as long as there is a flame at the pilot burner 20; a flame responsive device, such as a thermocouple 82, is disposed in the flame of the pilot burner 20 and is connected by a lead cable 84 to the magnet coil of the electromagnetic holding device 80. Since the voltage supplied by the thermocouple 82 is only great enough for holding and not for actuating the electromagnetic holding device 80, a reset button 86 protrudes therefrom. In order to provide a safe lighting feature, the reset button 86 overlies the lip of the plug valve dial 44 and moves through the notched portion 45 to permit depression of the reset button 86 when the dial 44 is in its pilot position. Thus, the plug valve dial 44 and reset button 86 are interlocked to prevent operation of the reset button except when the dial 44 is rotated to its pilot position.

The safety valve member 78 controls the pilot flow to a pilot flow conduit 88 which communicates with the pilot flow outlet 18 to supply the pilot burner 20. Intermediate its ends, the conduit 88 communicates with a bleed flow conduit 90 leading to one end of the plug valve slot 54, the other end of which communicates with a second bleed flow conduit 91. This bleed flow conduit 91 is controlled by a thermostatically operated valve 92 that is moved between a plurality of controlling positions by a thermally responsive operator 93. The operator 93 may be of any suitable type such as electric responding to a thermostat in the space being temperature controlled, or as shown on FIG. 1, the operator 93 may be a hydraulic type such as a bellows (not shown) that communicates with a capillary tube 94 having a thermally responsive bulb 95 on its other end. The bellows, capillary tube 94 and bulb 95 comprise a closed system filled with a thermally expansible fluid so that a variation of temperature sensed by the bulb 95 produces a corresponding expansion or contraction of the bellows. The bulb 95 is located in the space being temperature controlled by on-oflf operation of the burner apparatus 16, and the operator 93 includes a snap mechanism and temperature setting mechanism for the valve 92. Of course, other types of thermostats, such as the conventional rod and tube type, may be utilized in controlling operations of the main burner 16.

The bleed flow control valve 92 controls the bleed flow to a bleed flow outlet conduit 96 which has conventional flow restrictor 97 adjacent its opened end that communicates with the main flow outlet pressure chamber 34. Intermediate its ends and upstream of the flow restrictor 97, the bleed flow outlet conduit 96 has a branch bleed fiow conduit 98 which communicates with the operating pressure chamber 32.

The off position of the control device 10 is illustrated in FIGS. 3 and 4, wherein the plug valve 38 blocks the main inlet passage 12, the pilot flow conduit 58, and the bleed flow conduit 90; since there is no bleed pressure in the operating pressure chamber 32, the main valve 24 is closed on its seat 22 by the coil spring 52.

To initiate operation of the burner apparatus, the manual dial 44 is rotated from its off position to its pilot position which is represented by FIGS. 5 and 6, wherein the plug valve 38 has its pilot flow passage 56 in registry with the main inlet passage 12 and the pilot flow conduit 58, respectively. The reset button 86 is now depressed through the notch 45 of the dial 44 causing the electromagnetic holding device to move the safety valve 78 to its open position as illustrated in FIG. 1. A pilot How of fuel is now established and may be traced from the main inlet passage 12 through the plug valve pilot flow passage 56, pilot flow conduit 58, filter 60, pilot fiow pressure regulator 62, safety valve chamber 76, safety valve 78, pilot flow conduit 88 and pilot flow outlet 18 to the pilot burner 20 where it is ignited by any suitable means, such as a match.

As soon as the pilot burner 20 has heated the thermocouple 82 and the coil of the electromagnetic holding device is energized, the reset button 86 may be released whereupon the safety valve 78 will be held in its open position. During this operation of igniting the pilot burner, the plug value 38 is not in position to establish communication between the bleed flow conduits and 91; thus, there is no bleed flow to the operating pressure chamber 32. Accordingly, there is no pressure differential on the main diaphragm 30 and the main valve 24 remains closed by the bias of the coil spring 52 as is shown in FIG. 5.

After release of the reset button 86, the dial 44 is rotated from its pilot position of FIGS. 5 and 6 to its on position which is illustrated in FIGS. 1 and 2, wherein the plug wave 38 has its slot 54 aligned with the two bleed

flow conduits

90 and 91. It should be noted from the cross sectional views of FIGS. 1 and 5 and the cor-responding views of FIGS. 2 and. 6 that the plug valves pilot passage 56 has sufiicient arcuate length to retain registry with the main inlet passage 12 and the pilot flow conduit 58 when the manual dial 44 is in its on position and in its pilot position. In addition, the special porting 56 in the plug valve 38 is also utilized to communicate with the main inlet passage 12 and bypass the plug valve inlet 48 whereby a pilot flow of fuel is directed to the pilot flow passage when manual dial 44 is rotated to its pilot position.

In its on position, the plug valve slot 54 establishes communication between the bleed

conduits

90 and 91 whereby a bleed flow may be traced from the pilot flow conduit 88 through the bleed fiow conduit 90, plug valve slot 54, bleed flow conduit 91, the opened bleed fiow control valve 92, the bleed flow outlet conduit 96 and the flow restrictor 97 to the outlet pressure chamber 34; between the bleed flow control valve 92 and the fiow restrictor 97, the bleed flow has a parallel path traced therefrom through the branch bleed flow conduit 98 into the operating pressure chamber 32. The flow restrictor 97 acts to maintain pressure in the upstream bleed line so that pressure developed in chamber 32 can act on diaphragm 30 to move valve 24 to its open position; consequently, the main valve 24 is moved to an open position by the diaphragm 30 acting against the bias of the coil spring 52. The greater force in the opening direction results from the substantially greater area of the diaphragm 30 compared to the area of the valve 24.

When the temperature requirements in the space being temperature controlled are satisfied, the thermostatically operated valve 92 is closed and bleed flow to the bleed flow outlet conduit 96 is cut off resulting in closure of the main valve 24. The operating pressure chamber 32 is now depressurized by bleeding the same to the main outlet pressure chamber 34 through a path traced from the operating pressure chamber 32 through the branch bleed flow conduit 98, the bleed flow outlet conduit 96 and the restrictor 97 to the main outlet pressure chamber 34 whence it is delivered through the main outlet 14 to the main burner 16. When the temperature requirements in the space being temperature controlled become unsatisfied, as determined by the thermal sensing bulb 95, the thermostatically operated valve 92 is opened whereupon the bleed flow to the operating pressure chamber 32 is reestablished and the main valve 24 is opened; the main burner 16 is again supplied with fuel that is ignited by the flame of the pilot burner 20.

The main burner 16 will be thus cycled thermostatically in accordance with the temperature demand sensed by the thermal sensing bulb 95. In the event the flame at the pilot burner 20 should be extinguished for any reason, the thermocouple 82 will cool and the electromagnetic coil of the holding device 80 will be deenergized causing closure of the safety valve 78. Since the safety valve 78 is upstream of the bleed flow conduit 90, the bleed flow to the operating pressure chamber 32 is also cut off whereby the main valve 24 is closed. The flame extinguishment at the pilot burner 20 thus results in the cut off of all fuel flow to the

burners

16 and 20. To reestablish the flame at the pilot burner 20, the igniting procedure outlined above mu'st be repeated; i.e., the dial 44 must be rotated to its pilot position before the reset button 86 can be depressed to move the safety valve 78 to an open position.

During normal operation of the burner apparatus, the present invention provides for both main flow and pilot flow pressure regulation. The pilot flow regulator 62 provides a regulated flow of fuel to the pilot outlet 18 and the pilot burner 20. Since the bleed line conduit 90 communicates with the regulated pilot flow line 88 downstream of the pilot flow regulator 62, the bleed line 90-98 supplies a controlled pressure flow to the operating pressure chamber 32 whereby a substantially constant loading is applied to the underside of main diaphragm 30. Main outlet pressure is sensed directly by the upperside of main diaphragm 30 to provide pressure regulation of the main flow to main outlet 14 and main burner 16.

By locating the pilot flow regulator 62 upstream of the bleed flow control valve 92, continuous operation of the sensing regulator 62 is obtained under operating conditions to provide continuous pilot flow regulation during operating on and off cycles of the main valve 24. In addition, the main valve 24 is guided during its movement by the guide stem 26 in the boss 50 so as to have a separate guided movement by not being directly attached to the diaphragm 30. Since the valve stem 28 is pushed by the diaphragm action without direct connection thereto, any biasing of the main valve 24 due to diaphragm buckling is minimized.

By porting the bleed flow through the plug valve slot 54 upstream of the operating pressure chamber 32, the plug valve 38 provides an extra safety feature in that the bleed flow is subject to manual on-off control. When it is desired to shut down the burner apparatus, the manual dial 44 is rotated to its off position (FIG. 2) wherein all fuel flow is shut off. It should also be noted that the present arrangement has an additional in the control system would preclude the supply of pressure to the operating pressure chamber 32; thus, the pressure-to-open diaphragm valve arrangements constitutes a fail safe system which retains the main valve 24 closed in the absence of the required pressure to operate the main diaphragm 30.

Inasmuch as the present invention is subject to many modifications, variations and changes in detail, it is intended that all matter contained in the foregoing description of the preferred embodiment or shown on the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a control system for main and pilot burner apparatus, the combination comprising a casing having inlet means adapted for connection to a source of fuel, main outlet means adapted for connection to the main burner, and pilot outlet means adapted for connection to the pilot burner,

main valve means disposed between said inlet and main outlet means for controlling a flow of fuel to the main burner, diaphragm means for moving said valve means and defining an operating pressure chamber in said casing,

pilot flow means adapted for communication with said inlet means and being connected to said pilot outlet means to supply a pilot flow of fuel to the pilot burner, bleed flow means having one end communicating with said pilot flow means and another end communicating with said outlet means, and having branch bleed flow means intermediate its ends communicating with said operating pressure chamber,

control means controlling a bleed flow of fuel to said operating pressure chamber and effecting operation of said diaphragm means to move said valve means, and

pressure regulating means in said pilot flow means upstream of said bleed flow means for regulating the pressure of the pilot flow of fuel and for regulating the pressure of the bleed flow of fuel.

2. The invention as recited in claim 1 wherein manually operated on-otf valve means is disposed in said casing adjacent said inlet means to control a flow of fuel into said casing.

3. The invention as recited in claim 2 wherein said on-otf valve means includes porting means to control the bleed flow of fuel through said bleed flow means.

4. The invention as recited in claim 3 wherein the porting means of said on-olf valve means controls the bleed flow of fuel upstream of said branch bleed flow means.

5. The invention as recited in claim 3 .wherein said bleed flow means includes spaced first and second bleed flow conduits intercepted by said on-ofi valve means, and said porting means establishes communication between said first and second bleed flow conduits.

6. The invention as recited in claim 5 wherein said on-oif valve means comprises a rotatable plug valve and said porting means comprises peripheral opening means in said plug valve for movement into and out of registry with said first and second bleed flow conduits upon rotation of said plug valve.

7. The invention as recited in claim 2 wherein said on-oif valve means includes an inlet opening registerable with said inlet means and a valve chamber communicating with said inlet opening, and wherein said main valve means controls a main flow of fuel out of said valve chamber.

8. The invention as recited in claim 7 wherein said main valve means includes a valve disc movably disposed in said valve chamber and a valve stem extending from said valve disc, and wherein said diaphragm means engages said stem to move said valve disc.

9. The invention as recited in claim 8 wherein said on-off valve means includes a centrally bored boss ele- 8 ment in said valve chamber, and said valve disc has a FOREIGN PATENTS guide stem slidably disposed in said centrally bored boss 797,510 7/1958 Great Britain element to guide said valve disc during its movement.

FREDERICK L. MATTESON, 111., Primary Examiner.

References Cited UNITED STATES PATENTS 3,126,911 3/1964 Galley 236-80 X US. Cl. X.R. 3,300,174 1/1967 Urban et a1 236--80 X 137-495 5 EDWARD G. FAVORS, Assistant Examiner.