US2733756A - Control device for manually operated oil burners - Google Patents

Description

Feb. 7, 1956 J. R. DAY 2,733,756

CONTROL DEVICE FOR MANUALLY OPERATED OIL BURNER-S Filed June 22, 1953 mvemron, JOHN DAY Arrom as.

United States Patent CONTRUL DEVICE FQR MANUALLY OPERATED 01L BURNERS John R. Day, Juelph, Gntario, Application June 22, 1953, Serial No. 353,232

3 Claims. (3. 158-28) This invention relates to a control device for regulating the supply of fuel and air to the Combustion chamber of a burner, and while not limited thereto, relates more particularly to a control device for a manually operated oil burner such as is used in space heaters, converted coal and wood stoves, and the like.

The principal object of the invention is to provide an easily operated control device which ensures safe operation of a burner at all times.

Burners of the type with which this invention is concerned are usually supplied with fuel through a metering valve and with air from a fan driven by an electrically operated motor. if there is a power failure the motor stops but in many burners now on the market the supply of oil to the burner continues without interruption. The oil supplied to the burner during the power failure may continue burning to some extent but the combustion is unsatisfactory because there is insufficient oxygen in the combustion chamber of the burner; consequently there is an accumulation of unburnt oil, and when the power comes on again and the fan starts up there may be an explosion.

in many heaters and ranges in which manually controlled buiners are used there is an imperfect draft and consequently unburnt oil accumulates; this is particularly the case where the control is set for pilot operation, burning during pilot operation often being incomplete. Also, when starting up a cold burner puddling of oil is apt to occur while the burner is warming up. Consequently when conventional burners have been out of use for a short period there is considerable danger of an explosion when the burner is started up, or the combustion is apt to be very poor, resulting in a dirty combustion chamber and flues.

Another drawback of most conventional burners is that as the supply of oil is increased by adjusting the metering valve it is necessary to adjust simultaneously a damper for increasing the supply of air from the fan.

I t is an object of this invention to provide a burner control device which avoids the above-mentioned disadvantages, which is simply constructed, and which is easy to operate.

To reduce the dangers resulting from power failure it has been proposed, in U. S. Patent 2,266,974 issued December 23, 194-1, to Roy W. Johnson, to provide a mechanism for disconnecting the motor and impeding the flow of oil on a power failure, which mechanism must be manually reset before the burner can again be operated. The mechanism depresses a pin which reduces the flow of oil to pilot rate, and opens a switch to the fan motor. However, the mechanism shown in the aforesaid patent is complex and it is an object of this invention to provide a simpler mechanism.

In U. S. Patent 2,476,870 issued July 19, 1949, to Milton D. Huston it is proposed to provide a rheostat for increasing the speed of the fan motor as the supply of oil is increased by the metering valve, thus eliminating the need for simultaneously adjusting a damper, and it is also proposed to provide an independently operable starting lever for depressing a button which impedes the oil supply while the motor is operating at a high speed, thus avoiding flooding. According to the present invention means are likewise provided for increasing the speed of the fan motor as the supply of oil is increased, but the need for an independently operable lever to prevent floodin g is eliminated, the button of the aforesaid Huston construction thus being rendered available for a mechanism to achieve the results of the aforesaid Johnson construction; the elimination of the starting lever of Huston permits the use of a mechanism which, on a power failure, disconnects the fan motor as well as depressing the button to impede the supply of oil.

(Ether objects and advantages of the invention will becom" apparent from the following description of a preferred control device as illustrated in the accompanying drawings in which:

Fig. l is a partly sectional side view of a control device mounted on the top of a casing which encloses a conventional fioat valve assembly and metering valve for supplying oil to a burner;

.Fig. 2 is a top view taken on the plane 22 of Fig. l and with the lid of the control device partly broken away;

Pig. 3 is a fragmentary sectional View taken on the plane 3-3 of Fig. 2; and

Fig. 4 is a so emetic diagram of the electrical circuit of the control device.

A casing ll has an inlet 2 for oil, an inlet valve 3 controlled by a main float 4 to maintain a constant level of oil within the casing 1, and a safety shut-off mechanism 5 controlled by a safety float d. An oil outlet 7 from the casing i is controlled by a metering valve 8, the valve 8 being adjustable from closed to open position by means of a rotatable knob 9 on the lid of the casing i. Furtherinor the flow of oil through the valve 8 can be reduced to pilot value instantaneously by depressing a reciprocatable element or button it which projects from the top of. the casing Means including an arm lliia are provided for biasing the element it upwardly so that the valve 8 is normally controlled by the knob 9, but in Fig. l the element ill is shown being held in its depressed position by a weight U which will be described hereinafter. Apart from the weight Ill, the apparatus so far described is conventional and forms no part of the present invention; similar apparatus is shown, for example, in U. S. Patent 2,293,903 issued August 25, 1942, to Roy W. Johnson.

Secured to the lid of the casing 1 is a second casing 12 which encloses the knob 9 and weight 13.. Supported by the casing 12 at its top is a control knob 13 having a shaft 14- extending downwar iy into the casing 12, as best seen in Fig. 3. At its lower end the shaft 14 is flattened as at Ma and extends into a narrow slot 9a in the knob 9, whereby rotation of the knob 13 causes rotation of the knob 9 and adjustment of the metering valve Within the casing 12 is a platform 12a through which the shaft 14- passes and on which is arranged, in circular fashion around the shaft 14, a plurality of contacts 16a, 16b, 16c, 16d, Me, to and as well as a curved conductive strip 17'. As best seen in Fig. 4, where, for clarity, the contacts curved strip are shown in a slightly different physical arrangement than in the other figures, the contacts 16a, log and 367 are connected through a line L: to one side of an alternating voltage source V, and the contacts 16!), inc, 16c], 16c and 16 are connected to taps on an inductance coil 19. The strip 17 is connected by a wire ill to one side of a fan motor 22, the other side of the motor being connected by wire 23 to one side of a switch 24 the other side of the switch 24 being connected by a line 25 to the voltage source V. Mounted on the 0 shaft 14 is an insulated arm 26 carrying a downwardly spring-pressed contact 27 adapted to connect the contacts 16a 16g to the strip 17.

Assuming for the moment that the switch 24- is closed and that the arm 26 is in the position illustrated whereby the contact 16a is connected to the strip 17, the inductance coil 19 is out of the circuit and the motor 22 receives full voltage from the source V and rotates at maximum speed, if the kno 13 is turned, moving the contact 27 to corn nect the contact 16b to the strip 17, it will be seen that the entire inductance coil 19 is connected in series with the motor 223 so that the voltage applied to the motor is considerably reduced and consequently its speed is much lower than it was initially. As the knob is turn farther, the contacts lac, ltd i, no and bit are successively connected to the strip 35.7, less ant less of the inductance coil 19 is in series with the motor 22, and the motor speeds up. Assuming also for the moment that the element ill is in its upper position rather than in the depressed position shown in Fig. l, the metering valve 55 controls the supply of oil to the outlet 7 as the corn tact 27 moves from the contact lea over the contacts 16b, 160, etc. to the contact log the flow of oil from the 1 outlet 7 increases from zero to full rate of flow. Thus, with no oil flowing to the outlet 7 and hence to the oil burner, the motor 22 is driven at maximum speed and the supply of air to the combustion chamber of the burner is a maximum. However, at contact lob, the supply of air is reduced and thereafter increases as the flow of oil increases.

Connected across the lines 218 and 23 through a high temperature limit control hereinafter referred to is a solenoid 23 having a movable iron core 29 shown in Figs. 1 and 2. The core 29 is coupled by a ring Ell to a lug 11a on the weight 11. The weight ll is pivotally mounted as at 11b within the casing 12, and has a downward projection 110 which, when the weight is in the position shown in Fig. l, depresses the element lit; the latter, through conventional means, reduces the flow of oil through the outlet 7 to pilot rate.

Connected to the weight 11 is a rod 31 which extends upwardly through the top of the casing 12 where it can be grasped manually. If the rod 31 is pulled upwardly, the weight 11 pivots at 11b and also moves upwardly, the core 2Q moving into the solenoid 2%. When the weight 11 is pulled upwardly, a projection ila' strikes a button 24a on the switch 24, closing the switch, and also the projection llllc is moved out of contact with the element lil which moves upwardly under the influence of its biasing spring so that the flow of oil through the outlet 7 is thereafter controlled by the position of the knob 13. In Fig. 4, the core 29, weight 11 and rod 31 are shown schematically as a core 29 which can be moved to close switch 24.

Operation Assume that the parts are in the position shown in the drawings. To begin operation of the burner, to which the outlet 7 is attached, the rod 31 is pulled upwardly, permitting the element iii to move upwardly and closing the switch 2 2-. The solenoid 28 is thereby energized and thus holds the weight i l in the upper switch-closing location to which it is moved by the rod Eli. The motor 22 receives full voltage through the contacts 16a, 27 and the strip 17, so that air is supplied to the combustion chamber of the burner at a high rate while there is no flow of oil. Since the motor receives full voltage at the outset it has no difliculty in starting.

The knob 13 is then turned to permit the flow of oil to the outlet '7, simultaneously connecting the inductance coil 19 in series with the motor to reduce its speed, but gradually cutting out the inductance coil 19 and thus increasing the speed of the motor as the knob 13 is turned to the fully opened position of the metering valve 8. it will be noted that from the contact 16b to the contact 16g there is a variable control of motor speed as the rate of flow of oil is varied, so that it is not necessary to adjust air dampers for the burner, the result being quiet 5 operatlon and the elimination of bad damper ad ustment. 7

After moving the arm 26 around to the contact 16g, whereby an initial charge of oil is fed to the burner, the operator returns the knob 13 and thus the arm 26 to the initial position illustrated where there is plenty of air supplied to the combustion chamber but no oil. The knob is held in this position for a short period until the oil initially admitted to the combustion chamber is burned, the draft is going properly, and the combustion chamber has begun warming up, and the knob 13 is then moved to any desired position for subsequent continuous operation of the burner. if it is desired to turn the burner oii, the knob 13 is returned to the position illustrated, the motor operates at a high speed to burn up any remaining oil in the burner, and the rod 31 is then depressed manually, causing the weight ill to move to its lower location where it depresses the element 10. At the some time, the projection lid moves out of contact with the button 24;: of the switch 24- and the switch 24 opens, die-energizing the solenoid 23 and the motor 22. it will be seen that the rod 31 operates as a manual tripping device which eliminates the need of an external switch for starting or stopping.

if a power failure should occur while the burner is operating, the solenoid 225 will be de-energized, permitting the weight ll to fall to the position illustrated and shut oif the fan motor and reduce the flow of oil to pilot rate. If the power should then come back on, the rod 31 must be raised manually before operation can be resumed, and therefore the operator can check the condition of the burner to insure that an explosion will not occur when he restarts the burner. Furthermore when the burner is restarted the control device in the initial position illustrated provides a large flow of air to the burner and no oil, any danger of an explosion thus being minimized.

If the line voltage should drop to a point that would be detrimental to the motor 22, the solenoid 28 can be designed to permit the weight 11 to fall, reducing the oil supply to pilot rate and shutting off the motor which cannot start up again until the operator is in attendance.

The stove, furnace or boiler in which the burner is used, or the stack, may be provided with a thermostatic high temperature limit control 32 in series with the solenoid 28 so that if there is any overheating the control 32 opens the circuit to the solenoid 28 and again the oil supply is impeded and the fan motor is shut off until manually restarted.

An advantage of using the tapped inductance coil 19 is that relatively little heat is generated when the inductance coil is in series with the motor, and consequently the impedance of the coil does not change over a long period of operation; the same would not be true of a tapped resistor.

An important feature of the invention is the use of a weight 11 to impede the flow of oil and shut oil the motor: the gravitational action of a weight can be depended upon, whereas the use of some sort of spring loaded shutoff device is inherently undependable. It is to be noted that the use of a weight 11 can be extended to automatically controlled burners in which the Weight is permitted to fall when the voltage across the solenoid 28 is reduced to a predetermined value and in which the weight is automatically returned to its upper position by the solenoid when full voltage is restored.

It will be seen that a control device has been provided having the desired safety features mentioned in the introduction of this specification, the mechanism of the control device being simple and easy to operate.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of the parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

What I claim is:

1. A control system for the supply of fuel and air to a combustion chamber, comprising a metering valve for regulating the rate of flow of fuel to the combustion chamber; a motor and a fan driven thereby for producing flow of air to the chamber; and a control device comprising adjustable valve control means operatively associated with the valve for increasing and decreasing the rate of flow of fuel through a predetermined range of rates of flow, motor speed control means including a member positionable by the adjustable valve control means to increase and decrease the speed of the motor and thus of the fan between low and high values as the rate of flow of fuel is increased and decreased respectively through said range, said member also having a position to which it is movable by the adjustable valve control means when the latter is moved to the low end of said range, and means operatively associated with said member in said last named position for setting the speed of the motor at a high value.

2. A control system for the supply of fuel and air to a combustion chamber, comprising a metering valve for regulating the rate of flow of fuel to the combustion chamber; an electric motor and a fan driven thereby for producing flow of air to the chamber; and a control device comprising a first movable member operatively associated with the valve for increasing and decreasing the rate of flow of fuel through a predetermined range of rates of flow, electrical means for applying voltage to the motor and having a second movable member positionable to vary the voltage applied to the motor between high and low values and thus to vary its speed and that of the fan, the second movable member being coupled to the first for movement therewith whereby as the first member increases and decreases the rate of fiow of fuel through said range the second member increases and decreases respectively the speed of the motor, and the second movable member having a position to which it is movable by the first member when the first member is moved to the low end' of said range, and means operatively associated with the second movable member in said last named position for providing a high voltage to the motor.

3. A control system for the supply of fuel and air to a combustion chamber, comprising a metering valve for regulating the rate of flow of fuel to the combustion chamber; a fan; an electric motor which when connected to a voltage supply drives the fan for regulating the rate of flow of air to the chamber; and a control device comprising a first movable member operatively associated with the valve for increasing and decreasing the rate of flow of fuel through a predetermined range of rates of flow, electrical means for applying voltage to the motor from the supply and having a second movable member positionable to vary the voltage applied to the motor between high and low values and thus to vary its speed, the second movable member being coupled to the first for movement therewith whereby as the first member increases and decreases the rate of flow of fuel through said range the second member increases and decreases respectively the speed of the motor, the second movable member having a position to which it is movable by the first member when the first member is moved to the low end of said range, and contact means operatively associated with the second movable member in said last named position for providing a high voltage to the motor, and means responsive to a predetermined drop in supply voltage for disconnecting the motor from the supply and impeding the flow of fuel to the combustion chamber.

4. A control system for the supply of fuel and air to a combustion chamber, comprising a metering valve for regulating the rate of flow of fuel to the combustion chamber; a fan; an electric motor which when connected to an alternating voltage supply drives the fan for regulating the rate of flow of air to the chamber; and a control device comprising a knob coupled to the valve for increasing and decreasing the rate of flow through a predetermined range '6 of rates of flow as the knob is turned, an inductance coil connected in series with the motor and having taps, a con tact arm connected to the knob and movable therewith over the taps for varying the inductance in series with the motor thus varying its speed, the speed being increased and decreased as the rate of flow of oil is increased and decreased respectively through said range, the contact arm having an initial position which it occupies when the knob is set at the low end of said range, and a contact cooperating with the contact arm in its initial position to shunt the inductance whereby the motor rotates at high speed.

5. A control system for the supply of fuel and air to a combustion chamber, comprising a metering valve for regulating the rate of flow of fuel to the combustion chamber; a fan; a motor which when connected to a supply drives the fan for regulating the rate of flow of air to the chamber; and a control device comprising a first movable member operatively associated with the valve and movable through a number of positions for increasing the rate of flow of fuel through a predetermined range of rates of flow, and motor speed control means having a second movable member, the second movable member being coupled to the first for movement therewith from an initial position of the second member through a number of subsequent positions as the rate of flow of fuel is increased by movement of the first member, and motor connecting means operatively associated with the second movable member at its initial and subsequent positions, the second movable member at the initial position connecting the motor through the motor connecting means for rotation at a high speed and at the subsequent posi* tions connecting the motor through the motor connecting means for rotation at speeds increasing from a speed lowor than said high speed.

6. A control system for the supply of fuel and air to a combustion chamber, comprising a metering valve for regulating the rate of flow of fuel to the combustion cham her; a fan; a motor which When connected to a supply rives the fan for regulating the rate of flow of air to the chamber; and a control device comprising a first movable member operatively associated with the valve and movable through a number of positions for increasing the rate of flow of fuel through a predetermined range of rates of flow, motor speed control means having a second movable member, the second movable member being coupled to the first for movement therewith from an initial position of the second member through a number of subsequent positions as the rate of flow of fuel is increased by movement of the first member, motor connecting means operatively associated with the second movable member at its initial and subsequent positions, and manually operable means for connecting the motor to the supply with the second movable member at the initial position, the second movable member at the initial position connecting the motor through the motor connecting means for rotation at a high speed and at the subsequent positions connecting the motor through the motor connecting means for rotation at speeds increasing from a speed lower than said high speed.

7. A control system for the supply of fuel and air to a combustion chamber, comprising a metering valve for regulating the rate of flow of fuel to the combustion chamber; a reciprocatable element movable downwardly to impede said flow and upwardly to permit said flow; a fan; an electrical motor which when connected to a voltage supply drives the fan for regulating the flow of air to the chamber; and a control device comprising a first movable member operatively associated with the valve and movable through a number of positions for increasing the rate of flow of fuel through a predetermined range of rates of flow, motor speed control means having a second movable member, the second movable member being coupled to the first for movement therewith from an initial position of the second member through a number of subsequent positions as the rate of flow of fuel is increased by movement of the first member, motor connecting means operatively associated with the second movable member at its initial and subsequent positions, a solenoid, circuit means including a switch closable to connect the solenoid and the motor to the voltage supply with the second movable member at the initial position, the second movable member at the initial position connecting the motor through the motor connecting means for rotation at a high speed and at the subsequent positions connecting the motor through the motor connecting means for rotation at speeds increasing from a speed lower than said high speed, a third member associated with the solenoid and manually movable from a lower to an upper location, the third member in the upper location closing said switch and being retained in said location by the solenoid, the solenoid upon a predetermined drop in supply voltage releasing the third member which is free to fall gravitationally to the lower location whereby the switch opens, the third member in the lower location holding the reciprocatable element downwardly, and means for holding said element upwardly when the third member is in the upper location.

8. A control system for the supply of fuel and air to a combustion chamber, comprising a reciprocable element movable downwardly to impede the flow of fuel to the combustion chamber and upwardly to permit said flow; a fan; an electrical motor which when connected to a voltage supply drives the fan for regulating the flow of air to the chamber; and a control device comprising a solenoid energizable from the voltage supply, circuit means including switch means having a closed position for connecting the motor to the voltage supply and an open position for disconnecting the motor from the supply, a weight associated with the solenoid and movable between an upper and a lower location, the Weight in the upper location holding the switch means in the closed position and being retained in the upper location by the solenoid when the voltage across the solenoid is a predetermined value, the solenoid when the voltage across it falls below the predetermined value releasing the weight which is free to fall gravitationally to the lower location whereby the switch means takes up the open position, the weight in the lower location holding the reciprocatable element downwardly, and means for holding said element upwardly when the weight is in the upper location.

Cited in the file of this patent UNITED STATES PATENTS 1,657,436 Munro Ian. 24, 1928 2,266,974 Johnson Dec. 23, 1941 2,476,807 Breese July 19, 1949 2,476,870 Huston July 19, 1949 2,584,281 Morlock Feb. 5, 1952 FOREIGN PATENTS 421,333 Great Britain Dec. 10, 1934

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