US 3394886 A
Description (OCR text may contain errors)
July 30, 1968 R. G. BUDDEN CONTROL DEVICE FOR GAS BURNERS Filed Feb. 23, 1966 IEIZI? y INVENTOR.
ATTORNEYS I H I;
II II n I I I li'liiiiiiiii'l'lz' United States Patent 3,394,886 CONTROL DEVICE FOR GAS BURNERS Robert G. Budden, Clarence, N.Y., assignor to Roberts- Gordon Appliance Cor oration, Buffalo, N.Y. Filed Feb. 28, 1966. Ser. No. 530,645 Claims. (Cl. 237-2) ABSTRACT OF THE DISCLOSURE This disclosure relates to infra-red heaters particularly designed to obtain the correct proportions of fuel and air at sub-atmospheric pressures, even if the pressure of air or gas varies. An air filter is supplied in the air passag and the control device maintains the correct proportions of air and gas even if the filter becomes partly blocked, resulting in a reduction of the air supply.
An object is to provide a control device of this kind with an air filter and in which the control device maintains a correct proportion of air and gas even if the air filter becomes partly blocked so that the supply of air is reduced.
In the accompanying drawings:
FIG. 1 is a vertical, cross-sectional view, partly diagrammatic, of a control device embodying this invention.
FIG. 2 shows a diagrammatic view illustrating variously arranged heating systems in which control devices embodying this invention may be used, the view having been taken from the opposite side shown in FIG. 1.
FIG. 3 is a fragmentary sectional view on line 33, FIG. 1.
FIG. 2 shows a heating system of the kind in which my improved control device may be employed and includes a number of heating devices, each including a combustion chamber 6. 11 represents control devices to which air and gas are supplied and from which a combustible mixture of these two ingredients is supplied to a combustion chamber.
8 represents a vacuum pump driven by a motor 9 and which may take products of combustion from the control devices 1 1 or from the outer air and withdraw products of combustion from the pipe 10 and establish a par tial vacuum in this pipe. This invention relates particularly to the control devices 11, one of which is shown in FIG. 1, and includes a suitable housing or cavity which is capable of being essentially air-tight to which the admission of air is controlled through an air inlet duct 16 which may have an air chamber 17 arranged therein so that the air entering the inlet duct through an opening 18 must pass through the air cleaner before entering the housing 15. 19 represents a valve or damper by means of which the supply of air to the inlet duct 16 may be controlled.
22 represents a gas pipe which in the construction shown extends into the housing 15 and has a branch 24 leading to a burner 25 arranged in the combustion chamber 6. 27 represents another branch connected with the gas pipe 22 for supplying gas to a pilot burner.
The gas passing to the main burner 25 flows through a valve 29 including a transverse wall 28 having an opening controlled by a damper 30 which is mounted on a flexible diaphragm 31 which is held in place by means of a cap 32 in the housing 15 and having an air inlet 33 through which air from the housing 15 may pass to act ice on the upper surface of the diaphragm 31 to which the valve 30 is connected.
The pipe 24 contains another valve of Well known construction including a valve disk or damper 35 controlling an opening in the valve 36 in the gas passage, and suitably controlled electrically, for example, by means of solenoids. This electric valve 37 may be controlled by a thermostat located in the space to be heated and is normally open fully but will close when the supply of heat is to be interrupted so that no gas will flow through the pipe 24 to the burner.
The branch pipe 24 of the gas pipe 22 is also provided at 40 with a fixed restriction through which the supply of gas to the burner is restricted as desired. The pipe 24 then discharges gas into a mixing duct 43 leading to the burner. Adjacent to the elbow 42 the mixing conduit 43 is provided with an inlet for air which may be of any desired construction, that shown including an opening or orifice 44 from the interior of the chamber 15, and a plate or suitable control device 45 is provided which may be adjusted permanently to a position in which the correct amount of air is supplied through the orifice 44 for mixture with the gas discharged to the mixing duct 43. This mixing duct 43 terminates at its lower end in the burner 25 located in the combustion chamber 6.
The branch pipe 27 leading from the gas pipe 22 conducts fuel to a pilot burner 48 of any usual or suitable construction. In the structure shown, this branch pipe 27 passes to a gas supply valve 49 which may be similar to the valve in the branch pipe 24, including a valve disk or damper 50 controlling an opening in a transverse wall 51 of the pipe 27. The disk or damper 50 is mounted on a flexible diaphragm 52 which is held in place by means of a cover 53 having an air inlet opening 54. From this control valve the gas passes to another electrically controlled valve 56 similar to the valve 37, and a fixed restriction 58 is provided in this pipe to restrict the flow of gas to that part of the burner. The pilot gas pipe terminates in an elbOW 60 leading to a mixing chamber or duct 61 to which air is admitted, for example, through an orifice 62 controlled by means of a plate 63 extending partly across this opening. This air orifice and the air orifice 44 require no adjustment when correctly set. The mixing duct 61 for the pilot burner terminates at the pilot burner. Combustion of the gas discharged at the pilot burner may be effected in any suitable manner, for example, by means of a spark plug 65 having terminals 66 adjacent to the gas discharge opening of the pilot burner.
The mixing duct 61 terminates in an enlarged space and the spark plug is provided with a tubular extension which extends through this space and has screw threads for securing the same to the burner housing. The spark plug also has apertures in the wall of the tubular extension, into which combustible mixture from the mixing duct 61 may enter and flow within the tubular extension of the spark plug directly to the terminals 66 thereof. The burner housing is also provided with a series of passages 76 extending from the enlarged part of the mixing duct 61 downwardly into the combustion chamber, these passages 76 being arranged about the spark plug. In the op eration of this pilot burner, products of combustion passing through the small apertures 75 in the spark plug are discharged in immediate proximity to the terminals 66 and consequently a small flame is started at the base of the spark plug, and this small flame ignites the combustion products which flow through the passage 76, thus producing a very positive ignition of gases in the pilot burner at the spark plug.
As is well known, when the electric valves 37 and 56 are moved into closing position, the flow in the gas pipes 24 and 27 will of course be interrupted. This will result in the building up of gas pressure in these pipes leading to the electric valves which will be greater than the air pressure in the housing and consequently the gas will exert greater pressure on the two diaphragms 31 and 52 and thus move the valve disks 30 and 50 into closing positions so that no gas will pass to the burner nor to the pilot burner.
The main burner 25 is located in the combustion chamber 6 and the pipe 10 carrying products of combustion from another burner, or air, if no other burner is in operation, passes into the combustion chamber 6 and mixes with the flame and products of combustion discharged from the burner 25. A wall 70 forms an extension of the mixing chamber 43 and when the burner is in operation this wall also deflects the products of combustion entering from the mixing chamber in a direction approximately parallel to the axis of the combustion chamber thus mixing with the products of combustion or air passing through the pipe 10.
It has been found desirable to deflect the air or prodnets of combustion entering through the pipe 10 in such a manner as to prevent this air from blowing the pilot flame away from the burner 25. For this purpose I have provided a baflie 80 which is partly circular to extend with a spring action to the side walls of the burner 25 but spaced from the lower wall thereof. This baflle springs into place against the inside walls and consequently prevents any air or products of combustion from the pipe 10 from passing into the combustion chamber 6 at the sides of the wall 70 so that all of this air or products of combustion pass below the bafi'le 80 which thus protects the pilot flame from any flow of air or products of combustion adjacent to the opposite sides of the wall 70.
As described in the Corey Patent #3,1l5,302 the combustion chamber 6 may be of any desired length. If a large amount of heat is required the products of combustion from the flame of the burner will be carried to the end of the combustion chamber so as to produce a larger area of the combustion chamber through which infra red heat may be discharged.
In the construction described, by means of the gas valves and the fixed orifices, a proper and constant proportional mixture of air and gas is assured when the pressure or partial vacuum varies in the pipe 10. Furthermore, this arrangement described will maintain a proportional mixture of air and fuel when the pressure in the air housing 15 is varied in relation to the external air pressure. Also, this arrangement will maintain a proportional mixture of air and gaseous fuel when the air pressure within the housing 15 is varied and when the pressure in the pipe 10 is varied simultaneously with the pressure in the housing. This functions in the following manner:
Air enters at sub-atmospheric or atmospheric pressure through. the air inlet 16 and gaseous fuel enters through the pipe 22 under a pressure more than atmospheric pressure. The gas flow then splits and one part flows toward the pilot control valves 50 and 56 and the other part to the main gas valves 29 and 36. As the gas flows through the regulating valves 29 and 50, pressure exerted on their diaphragms raises the valve steams attached to the diaphragm tending to close the valves, thus reducing the pressure at the points beyond these valves. At the same time, pressure from the interior of the housing 15 is exerting a force in the opposite direction on the diaphragms tending to open the valves. These valves will reach equilibrium when the pressure of the air corresponds to the reduced pressure in the pipe 42. These pressures consequently will be exactly the same as the pressures acting on the top surface of the diaphragms 31 and 52 and on the air orifices 44 and 62. These orifices are predetermined fixed orifices which admit the proper amount of air in order to create a combustible mixture of fuel and air for the pilot and main flame.
While the pressure of gas in pipe 22 is greater than atmospheric pressure, pressure acting on the diaphragms may be balanced because pressure of gas acting on the lower faces of the diaphragms is restricted by the disks 30 and s0. 1
With any partial vacuum or low pressure at the pipe 10 and burner 6, hydraulically this vacuum is also present on the down stream sides of the orifices 40, 58, 44 and 62 and a flow through these orifices will be established and become a function of the pressure differences on each side of these orifices. If the pressure in the pipe 10 is increased, fiow through these orifices wil remain proportional since the pressure differences at these orifices will remain equal to each other.
If the pressure in the housing 15 decreases either because the damper 19 is partly closed or because the filter 17 is partly clogged, the inlet pressure of air at the discharge orifices 44 and 62 will be reduced and less air will be admitted to the burner mixing chamber. If under these conditions the gas flow rate will remain constant, the mixture will no longer be properly proportional for combustion, but by means of the construction described, as the pressure in the housing 15 becomes reduced the air pressure in the diaphragms 31 and 52 will be less and will slightly close the valves 29 and 50, thus reducing the pressure of gas to the pressure corresponding to the pressure of the air acting on air orifices 44 and 62 so that the flow of air and gas is proportioned.
While I have described the gas pipe 22 as extending into the air housing 15, it will be obvious that this gas pipe may be arranged on the exterior of the air container or housing and suitable supply lines for air leading to the air orifices 44 and 62 and to the diaphragms 31 and 62 maybe provided. By conducting air for combustion through a filter, the entry of particles of dirt or other foreign material into the system is prevented, and risk of improper mixture of air and gas by having air pressure reduced by the filter as it becomes clogged is overcome by the construction described.
By including the baflie 80, the wall of the burner which extends into the combustion chamber is shielded from hot gases which may travel through the pipe 10. By maintaining the burner wall 70 at a lower temperature less heat is conducted into the combustible mixture within the passage 43. This prevents this mixture from reaching temperatures which would afl ect the flame propagation, which in turn affects the main burner flame stability.
It will be understood that various changes in the details, materials and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.
What is claimed is:
1. A control device for the supply of air and combustible gas to a burner, including:
a housing containing air at variable pressures;
an air inlet to said housing including a filter in said inlet through which the air passes;
a pipe for gaseous fuel extending through said hous a valve in said gas pipe responsive to variable air pressure in said housing to control the flow of fuel in said conduit according to the air pressure in said housing;
a mixing chamber leading to said burner and into which said pipe discharges fuel;
an orifice admitting air from said housing which is at the same pressure as that which controls the fuel pressure and discharging to said mixing chamber for mixture with the fuel discharged from said gas pipe;
a combustion chamber into which said mixing chamber discharges;
means for maintaining a sub-atmospheric pressure in said combustion chamber;
another pipe leading to said combustion chamber and carrying products of combustion from another burner to said combustion chamber, said combustion chamber constituting part of said other pipe and discharging its products of combustion into said other pipe.
2. A control device according to claim 1 and including means for controlling the flow of air through said inlet to said housing to control the air pressure in said housing.
3. A control device for the supply of a combustible mixture of air and gas to a burner, including:
a gas pipe for conducting fuel to the burner;
a valve in said pipe for controlling the rate of flow of gas in said pipe, including a valve controlling damper which is responsive to variable pressures in said housing;
a diaphragm connected with said damper and acted on by gas on one face thereof and by air at variable air pressure on the opposite face thereof to move said damper toward and from closing position;
a combustion chamber to which gas from said gas pipe is discharged, and
a fixed opening through which air under variable pressure is discharged to said combustion chamber.
4. A control device according to claim 3 and including a restriction in said gas pipe beyond said valve for reducing the fiow of gas to the burner.
5. A control device according to claim 3 and including an electrically operated valve in said gas pipe beyond said first-mentioned valve which shuts off the flow of gas in said gas pipe when no heat is required from said burner.
6. A control device for the supply of air and combustible gas to a burner, including:
an air inlet for said housing;
a pipe for gaseous fuel extending through said housing and divided into two branches, one leading to the burner;
a pilot burner connected with the other branch of said a control valve in each branch of said gas pipe, said control valves being responsive to the variable pressure of air in said housing and to fuel in said gas pipe controlling the flow of fuel in said pipe;
sid control valve each including transverse walls in said branch pipes and having openings therein;
a damper for each of said walls moveable toward and from said opening;
a diaphragm for each control valve connected with said damper and acted on one face by the air at variable pressure in said housing and on the opposite face by fuel in said pipe, said fuel also acting on said damper in a direction to close the same, and
means for supplying air from said housing for mixture with fuel discharged from each of said branch pipes said pressure responsive control valves maintaining equal pressure differentials across an air orifice and a gas fuel orifice for each of said burners.
7. A control device for regulating the supply of combustible gas to a burner, including:
a housing containing regulating apparatus;
an air inlet including a filter through which the air passes into said housing;
a fuel pipe for gaseous fuel extending through said housing;
valve means responsive to the variable air pressure in said housing and to fuel pressure in said fuel pipe to control the flow of fuel in said conduit in proportion to air pressure in said housing;
a mixing duct leading to said burner and into which said fuel pipe discharges fuel;
an orifice admitting air under variable pressure from said housing into said duct for mixture with the fuel discharged from said fuel pipe;
a combustion chamber in which said burner is located and which receives a mixture of fuel and air from said duct, and
means for maintaining a sub-atmospheric pressure in said combustion chamber.
8. A combustion chamber for gaseous fuel including:
a main burner and a pilot burner,
a housing having an air inlet leading to both of said burners,
a fuel pipe for gaseous fuel extending through said housing and divided to provide fuel to a main burner and to a pilot burner,
a mixing passage conducting fuel and air to said pilot burner,
a spark plug having a hollow tubular body portion extending through said passage and into said combustion chamber,
ignition terminals of said spark plug extending through and beyond said tubular body into said combustion chamber,
orifices in the part of said tubular portion which extend through said passage for conducting products of combustion from said mixing passage into said tubular portion for discharge into said combustion chamber,
and other orifices connecting said combustion chamber with said mixing passage for said pilot burner and in immediate proximity to said spark plug for conducting additional jets of combustible mixture to the flame from said tubular body of said spark plug.
9. A control device for the supply of air and combustible gas to a burner, including:
a housing containing air,
an air inlet to said housing,
a pipe for gaseous fuel extending through said housing,
means in said housing for mixing air and gas to produce a combustible mixture,
a combustion chamber including said burner and to which the combustible mixture is transmitted,
said burner extending into the middle portion of said combustion chamber,
a pipe leading to said combustion chamber and carrying products of combustion from another burner to said combustion chamber,
and a bafile in said combustion chamber between said other pipe and said burner and which extends to opposite sides of said combustion chamber and spaced from the bottom thereof to admit air and products of combustion from said other pipe to said burner.
10. A control device for the supply of air and combustible gas to a burner, including:
an air inlet for said housing,
a pipe for gaseous fuel extending through said housing and divided into two branches, one leading to the burner,
a pilot burner connected with the other branch of said a control valve in each branch of said gas pipe, said control valves being responsive to the variable pressure of air in said housing and to fuel in said gas pipe controlling the flow of fuel in said pipe,
said control valves each including transverse walls in said branch pipes and having openings therein,
a damper for each of said walls movable toward and from said opening,
a diaphragm for each control valve connected with said damper and acted on one face by the air at variable pressure in said housing and on the opposite face by fuel in said pipe, said fuel also acting on said damper in a direction to close the same,
means for supplying air from said housing for mixture with fuel discharged from each of said branch pipes,
a second valve in each branch responsive to the demand for heat from said burner and located beyond said control valves, said second valve when closed increasing the fuel pressure on said control valves to close the same,
and fixed flow reducing means in said branch pipe '3 through which the fuel passes after leaving said control valves.
References Cited UNITED STATES PATENTS 2,134,083 10/1938 Guenther et al. 126-91 2,369,746 2/1945 Miller 1269l 2,373,326 4/1945 Miller 12691 X 3,115,302 12/1963 Corey 237-2 10 EDWARD J. MICHAEL, Primary Examiner.