US2608999A - Electric delayed-impulse valve and switching circuit therefor - Google Patents

Description

P 1952 B. F. WHEELER 2,608,999

ELECTRIC DELAYED-IMPULSE VALVE AND SWITCHING CIRCUIT THEREFOR Filed March 9, 1949 2 SHEETS---SHEET l Inventor Byrizl i7 Wjzeeler By W Attorneys B. F. WHEELER Sept. 2, 1952 ELECTRIC DELAYED-IMPULSE VALVE AND SWITCHING CIRCUIT THEREFOR 2 SHEETS-SHEET 2 Filed March 9, 1949 4 Inventor flylizl'fl M00 01' Attorneys Patented Sept. 2, 1952 UNITED STATES PATENT 1 OFFIC ELECTRIC DELAYED-IMPULSE VALVE AND SWITCHING CIRCUIT THEREFOR Byrhl F. Wheeler, lialston Spa, N. Y. Application March 9, 1949, Serial No. 80,384

The present invention relates to electromagnetic valves and, more particularly, to an electricattachment for said valves causing a delayed electric impulse to actuate the valves. Such a system, as particularly adaptable to the improved operation of gun-type oil burners forms the subject matter of the present invention.

Inthe operation of oilburners of the gun-type, that isrhaving a pressure pump supplying oil under pressure to an atomizing nozzlaand a fan for-mixing combustion air with the atomized oil, it is an acknowledged fact that soot accumulations in boilers equipped with such burners is a function'o'f the repeated on and off operation of the burner itself, even when the fuel-air mixture is properly adjusted to optimum values.

This effect can be explained clearly by quoting extracts of an article appearing in the periodical Fueloil and Oil Heat of July 1948, written by S. H. Hulse and J. 0. Collins of the Standard Oil Development Co. laboratories:

A-major fault of most gun-type burners now in use is a short period of sooty combustion at the start of a burning cycle, when the oil pump delivers the full rated supply of oil before the burner fan has come up to speed, and again during shutdown when the air supply decreases at a faster rate than the oil supply. The Esso laboratories have found that the rate of soot deposit in a boiler is a function of the number of starts and stops in a given period. This is true even with a properly adjusted burner giving nominal smoke-free performance.

With the introduction, postwar, of devices such'as quickcut-off valves, smoky shutdowns can-be minimized. By means of a centrifugal clutch used on one make of burner between fan and pump, to time the pump operation, the formation of .sootboth at the start and end of the burning cycle is minimized." 7

Since the modern trends in fuel oilvrefining tend'to reduce volatility and increase density and flash points of fuel oils, the above remarks apply to a greater extent if eflflcientand clean burning of liquid fuels is to be obtained.

Obviously, the quick shut-01f valves and clutch mentioned supra represent either increased installation costs, incomplete delayedoperation, or cannot be installed into existing burner systems.

The present invention has been conceived to avoidthe disadvantages immediately above, while meeting completely the requirement of an oil supply sharply cut in after the air supply has reached its full-maximum, and sharply cut off before the fanhascommenced to slow down.

'2 Claims. (Cl. 137-691) 2 The main objectv of the invention, therefore, reside in the provision of an electrically operated delayed-action valve of improved character. Another important objectof the invention is the provision of an electric delayed-action cut-in valve and electric circuit for improving the operation of gun-type oil burners.

A further object contemplates a valve system of the character described which is simple, inexpensive, highly efficient for the purpose in view, adaptable to existing-installations and easy to service in the field. I

Still another object of the invention envisages an electric delayed-impulse valve system of highly versatile application for oil-burners, both new and old.

Other objects andv advantages of the invention will'become apparent, or be pointed out further, during the description to follow.

As an example'only, and for purposes of illustration, an embodiment of the invention is shown in the annexed drawings, wherein:

Fig. 1 is a perspective view of a fuel oil pump to which the valve of the invention has been attached;

, Fig. 2 is a side elevation view of the valve;

Fig. 3 is an enlarged side detail view of the electric contacting mechanism associated with the valve; 1

Fig. 4 is a perspective view of the thermal time delay switch plug;

Fig. 5 is a longitudinal section taken through the plug of Fig. 4, showing the thermal element in plan view; V

Fig. 6 is a similar section but taken at right angles to that of Fig. 5

Fig. fl is a diagram of connections for the valve shown in inoperative position; I V

Fig. 8 is a similar circuit diagram showing the valve and thermal element in operative positi n. l 1

Fig. 9' is yet another diagram of the circuit with the thermal element inoperative and the remaining parts in position for normal operation, and

Fig. 10 is a diagram of a modified circuit.

As stated previously, the invention contemplates the combination of an electro-magnetic valve with atime-delay switch and associated circuit. The valve itself is already known and, consists simply of a solenoid, or electro-magnet, adapted to move a valve needle, or disc, relatively to a seat: such valves are used fora variety of purposes, mainly: for the remote control of fluid flow, the automatic operation of devices,- liquid metering, etc. I v r In accordance with the present invention such a valve is used for the delayed cut-in of fuel oil flow in an oil burner and for the quick cut-off thereof at the end of the burning cycle, for reasons stated before.

This is accomplished by inserting the valve in the high pressure outlet line of the fuel oil pump of a burner, providing a thermal heating element of the bimetallic type for delaying the electric impulse initiating operation of the solenoid valve, and associating therewith an electric circuit and contacts, actuated by the valve itself, for shunting the heating element and forming a holding circuit for the solenoid, to maintain the valve open.

Referring now to the drawings, wherein similar reference characters represent corresponding parts throughout, the fuel oil pump P and solenoid valve V are commercially available together as a unit, although other types may be equally satisfactory. With this unit, the valve is mounted on the pump, as an integral member, and so connected as to control positively the outlet (not shown) of the pump. 1

'Said valve includesv the solenoid S inside, which the armature A is movable to actuate the valve needle (not shown) inside the pump assembly. Thesolenoid is mounted on a bracket B having side ears E one of which is apertured to receive the mounting clamps of electric conduit or flexible armored cable. A cover 0, shown in dotted lines in Fig. 2, encloses the whole mechanism.

Attached to the armature A there is a finger 10 adapted to actuate the contact bank D which switches on and oif the various elements of the pump-valve combination. Said bank is conveniently mounted upon the bracket B. and may consist of a plurality ofcontact blades spacedly mounted between insulating spacers 11 and clamped together by the .insulated rivet 12 to form the single unit D.

As shown to advantage in Fig. 3, the left hand blades 13-14 carry contact points 15-16 which are normally held in spaced open position: the right hand blades 11-18, in contrast, carry points 19-20 which tend to remain in contacting closed poition. The-blade 11' is extended above the adjacent blades to be engaged by the insulating stud 2| carried at the free end of finger 10. Said blade 11is further adapted, through the intermediary of a resilient insulatingstrip 22, to move the adjacent blade 14 for closing the contacts 15-16. Thus, without dealingnow with the specific function of the contacts and the circuits associated therewith, it is clear that movement of the armature A to open the enclosed valve will, also, operate to cause the stud 21 to open contacts 19-20 (by displacement of blade 1'1) and, thereafter, close the contacts 15-16 by the bending movement of blade 14 pushed by the strip 22 towards 13. Consequently, the finger 10 causes the opening of an electric circuitan'dthe almost simultaneous closing of another. I

The circuits so controlled are, respectively, the thermal delay switch and the solenoid holding circuit. The thermal switch is shown in Figs. 4 to 6 and resembles closely the usual domestic fuse plug in which a conventional light flasher has been mounted. This particular design is suggested since it is both simple, practical and inexpensive, although more elaborate time delay units enclosed in vacuum tubes and mounted on the so-called octal" base can be used as well. The advantage of using the inexpensive fuse plug design is the ease of servicing, it being con- 4 sidered more expedient to replace a unit rather than attempt its repairing or adjustment.

The thermal switch T consists of a porcelain body 25 inside which a bimetallic strip 26 is secured at 2'1, said strip having a contact point 28 at its free end and a winding of fine wire in-' sulated therefrom and constituting the heating element 29. A fixed contact 30 is adapted to be engaged by point 28, when the strip 26 is deformed by heat, said contact being integral with an end terminal 31 of the body 25. A threaded ferrule 32 is secured circumferentlally to the body and electrically connected to both one end of the heater 28 and the strip 26: the other end of the heater is connected to an intermediate contact ring 33 set on a recessed shoulder of the body concentrically with the terminal 31 (Fig. 5). Thus there is formed a three-contact plug which can be screwed in standard sockets having also a three-contact arrangement.

The components, of the combination are wired as shown in Figs.v 'Z-il-Q'wherein the three steps f the p tin cycle are iagrammatically epresented, and the assumption made, that the three contacts of the plug socket are numerically the same as the corresponding members on said plug.

T source o electric current o ener z n the solenoid and heating element isapplied; to the input wires 35-35 which, in practice, are those of the electric motor driving the pump P. The heater 29 is connected at one end to the 'wire 35 by means of a conductor 3'1 terminating at the ferrule 32: the other end of; said heater is joined to the wire 36 by means of a second conductor 41 completing the energizing circuit through the closed contacts. Therefore, as soon as the pump motor is energized, the wires 35-36 in parallel therewith will supply. current to the heater according to the circuit described above.

The heated strip 20 closing the contacts 28-30 will complete a secondary circuit through the solenoid S by means of conductors 38-39, whereby the said solenoid will be energized in turn, in the closed circuit 35-3'1-20-30-38-39-30, causing the armature to open valveV' and actuate contacts bankD ('Fig.;8)j. I

As previously explained, thefinger of the armature opens contacts 19-20 and closes 15-16: th contacts 10-20 being open, the heater 29 vnll cease to heat and, after a short delay due to heat inertia, open the contacts 20-30. So asto maintain the solenoid energized, however, a holding circuit is formed by the wire 40,.joining 38 to 35 through the closed contacts 15-16, thereby shorting the contacts 28-30. The heating element is therefore'placed entirely out of circuit, as shown in Fig. 9., I

In this position, thesolenoi'd S Will hold the valve open and remain energized: as long as current is supplied to theinput 35-36. and the pump motor connected thereto: thisis the normal running position ofthe combination, lwhether it is an oil burner or other device. Whenever the electric current i interruptedeven momentarily, the de-energized solenoid will release its armature to close the pump valve and. permit the contact bank to resumethe position of Fig. 7 the system is then ready fora-fresh operating cycle.

The present system combined, as described, with the oil pressure-pump of a fuel oil burner remedies radically the sooty'combustion at the starting and end of'each burning cycle. More specifically, the V delayed opening; of the? valve, corresponding to the time redu-ired-bythe thermal delay switch to close its contacts, allows the burner fan to attain its full speed and build inside the combustion chamber the air pressure and pattern at which the burner has been adjusted to run most efficiently. Thereafter, the oil supply is sharply cut in and ignited within properly swirling air currents, or cones, to produce an instant, smoke-free, flame.

In practice, it has been found that about five seconds is quite ample for the conditions above to occur, although with the general run of inexpensive heaters the time delay may be as high as fifteen seconds. It is not desirable, however, to go beyond fifteen seconds in order not to disturb unduly the time delay, of about two minutes, inherent to some systems of burner control before a safety shutdown of the burner is had in case of oil supply or flame failure.

At the end of a burning cycle, when the burner motor circuit is opened, the solenoid valve bein de-energized will snap the valve closed and cut off sharply the oil supply, even before the fan and pump have ceased to rotate. Therefore, the oil spray from the nozzle will stop while air of combustion is still supplied by the rotating fan: the result is, again, an absence of sooty combustion when the burner is shut down.

Thus, from the foregoing, it is clear that th present invention is an advance of the art of burning fuel oil. By means of simple and inexpensive means applicable to any system of pressure-atomized fuel oil more efficient combustion is obtained at the start and end of each burning cycle.

Servicing of the present combination, also, is reduced to an absolute minimum and replaceable elements are both inexpensive and readily ob tainable. Reliability is also another factor since the interlock between valve and contact bank is such that, in case of defects or trouble in the heating element, the system is rendered inoperative, that is, the oil supply will remain cut off until the burner safety controls operate to shut the burner down, as usual.

An interesting feature of this system has been observed also in small boilers which, having restricted combustion chambers and fine passages, were prone to that low frequency throbbing known as pulsation; an installation made in such boilers in accordance with the invention minimized or eliminated this trouble, due to improved air circulation in the boiler prior to oil admixture and ignition. 7

Examination of the diagrams'of Figs. 7-8-9 will readily reveal that a short momentary impulse only is required to operate the solenoid: the slightest movement thereof is sufficient to actuate the contact bank and cut the'holding circuit into play, whereupon the solenoid will remain energized as long as electric current flows therein. And, once the current has been interrupted, the released solenoid armature remains 1. As a fuel valve for oil burners, an electric valve biased to closed position, having a solenoid and an armature, an electric initiating circuit in combination with said solenoid and arranged when energized to open said valve, an electric holding circuitin combination with said valve solenoid, switch contacts in series with said holding circuit biased to circuit opening position, a

thermal time-delay switch in series with said initiating circuit and biased to open position including a heater adapted to be heated electrically and, when sufficiently heated, closing said thermal switch, contacts biased to closed position in series inactive until a recycling of the system has taken place, as described above, thus constituting a safety factor in addition to that normally obtained from the burner safety controls.

A slightly modified form is shown in Fig. 10 wherein a single contact blade 41 is actuated by the finger H) to move from heater contact 59 to solenoid contact 35. arrangement is rendered possible by the use of a This simplified contact with said heater circuit, said initiating circuit being arranged to shunt said holding circuit upon closure of the thermal switch, thereby initiating an impulse energizing the holding circuit, and connecting means between the valve armature and the holding circuit contacts and the heater circuit contacts for opening said heater circuit contacts and closing said holding circuit contacts upon opening of the valve.

2. As an improvement in fuel oil burners of the forced draught type, for introducing a time delay in the fuel supply after the forced draught means have been rendered operative by energization of a main electric circuit, a fuel valve normally closed and having an electric solenoid and armature actuating the valve proper from a closed to an open position, a single pole double throw valve switch also actuated by the solenoid armature and having two contacts closed when the valve is closed, an electric circuit in series with said closed contacts, said circuit being common with the main circuit and the electric heater of a thermostatic time delay switch, a pair of cont-acts on the time delay switch adapted to be closed when said heater has been sufficiently heated, the time delay switch contacts being in series with the ,main circuit and the solenoid for initially energizing the same and opening the valve and the closed contacts of the valve switch while closing the normally open contacts thereof, said contacts being in series with the main circuit for holding the solenoid energized.

BYRHL F. WHEELER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,029,710 Warner Nov. 12, 1935 2,221,667 Betz Nov. 12, 1940 2,282,197 Maynard May 5, 1942 2,299,404 Newton Oct. 20, 1942 2,385,699 ,Fox Sept. 25, 1945 2,401,393 Wakefield June 4, 1946 2,413,655 Russell Dec, 31, 1946

Images