US2968466A

US2968466A - Valve and control system

Info

Publication number: US2968466A
Application number: US542610A
Authority: US
Inventors: William J Mcgoldrick
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1950-11-02
Filing date: 1955-10-10
Publication date: 1961-01-17
Anticipated expiration: 1978-01-17

Description

1961 w. J. MCGOLDRICK 68,466

VALVE AND CONTROL SYSTEM Original Filed Nov. 2, 1950 INVENTOR.

WILLIAM J. MC GOLDRICK BY ATTORNEY statc VALVE AND CONTROL SYSTEM William .5. McGoldl-ick, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, New York, N.Y., a corporation of Delaware Original application Nov. 2, 1950, Ser. No. 193,713. Divided and this application Oct. 10, 1955, Ser. No.

2 Claims. (Cl. 251-129) valves and, more particularly, to a delay action valve for use in oil burner installations making use of blowers to provide combustion air.

One of the big problems in oil burner installations of the above mentioned type is the provision of satisfactory control means that will assure the necessary amount of air to support complete combustion of the oil, when said oil is admitted to the burner. The prior art means for accomplishing this result have taken different forms, all of which are somewhat complicated in structure, expen sive, bulky, and erratic in performance.

One of the objects of this invention is to provide a delay action fuel valve that is compact, durable, inexpensive and reliable in performance.

Another object of the invention is to provide a fuel valve wherein the time delay means for the energization of the valve is built into the valve.

Another object of the invention is to provide a solenoid valve having a negative temperature coeificient of resistance-type of resistor in series therewith to provide delayed action of the valve when energized.

A further object of the invention is to provide control apparatus for a fuel burner, comprising an oil valve and a primary combustion air fan or blower controlled in parallel by a thermostat or other control means, wherein a resistor having a negative temperature coefficient of resistance is in series with the valve to delay'opening of the valve until the fan or blower has come up to speed.

Still another object of the invention is to provide a delayed action solenoid valve wherein a resistor having a negative coefficient of resistance is imbedded in the solenoid coil and is connected in series with the wire forming said coil.

Other objects of the invention will become apparent upon reading the following detailed description of the invention in conjunction with the accompanying drawing wherein:

Figure l is a side view of the valve with a portion of its cover broken away;

Figure 2 is a cross-sectional view taken along the line 2--2 of Figure 1;

Figure 3 is a wiring diagram of a simple burner installation; and

Figure 4 is a modification of the valve wherein the resistor is wound within the coil of its motor means.

Referring to Figure l of the drawing, numeral designates a conventional solenoid valve body and the nu mera] 11 designates a conventional solenoid coil surrounding a plunger tube 12, the upper closed end of which is shown in cross-section in Figure 2 A resistor 13, having a negative temperature coefiicient of resistance, is connected by an insulated lead wire 14 to one end of the coil 11. The other end of the resistor is connected by an insulated lead wire 15 to an external control circuit atent Patented Jan. 17, 19%1 to be presently described. A pad 16, of any suitable heat insulating material, such as asbestos, is positioned between the resistor 13 and the coil 11 in the preferred form of the invention, as shown in Figures 1 and 2. The other end of the coil 11 is connected by an insulated lead wire 17 to the above mentioned external control circuit. Surrounding the resistor 13 and the coil 11 is a fiber insulating strip 18 which electrically and mechanically spaces the coil and resistor from a generally arrowshaped cover member 19 made of suitable magnetic material, such as steel. The cover 19 has an internally threaded conduit connector opening 19a, through which insulated

leads

15 and 17 extend. The cover 19 is held in position with respect to the valve body It} and the solenoid coil by means of a bolt 20 extending into a threaded bore (not shown) in the closed end of the plunger tube 12, in a conventional manner.

Referring to Figure 3 of the drawing, it will be noted that the lead wire 15 from the resistor 13 and a lead wire 21 from a fan 22 are both connected to one side of the secondary of a transformer 23. It will also be noted that the lead wire 17 and a lead wire 24 of the fan 22 are connected through line 25 to a movable contact arm 26 of a room thermostat. A fixed contact 27 of the room thermostat is connected by line 28 to the other side of the transformer secondary.

Operation Assuming that the valve is connected to a fuel burner along with the blower or fan 22 and the control apparatus therefor is connected as shown in Figure 3, upon a call for heat by the room thermostat, a circuit will be completed from one end of the secondary of the transformer 23 through line 28, fixed contact 27, movable contact arm 26, line 25, line 24, fan 22 and line 21 back to the lower end of the secondary of the transformer. A branch circuit, from line 25' through lead 17, valve iii, lead 14%, resistor 13, and lead 15 to the other end of the secondary of the transformer 23, will also be completed. As there is no resistance in series with the fan 22', it will immediately start and come up to operating speed. However, the resistor 13 is so chosen that when the circuit is completed through said resistor and the valve stem, the current flow through the valve will be insufficient to cause opening thereof immediately. Some current will flow, however, through both the valve 11 and the resistor 13 as to cause gradual heating up of the resistor 13. As the resistor heats up, the resistance thereof gradually decreases so that more and more current flows through the resistor until such a resistance is reached, that enough current is permitted to flow through the resistor and the valve 1 3' as to cause opening of the valve. By a suitable selection of resistor characteristics, it is apparent that the time delay between the energization of the fan and the opening of the valve 10 may be accurately determined and controlled. This time delay Will usually be the time required for the fan to come up to substantially normal operating speed following the energization of the fan.

When the room thermostat or limit control has become satisfied, breaking the circuit to both the valve and the fan, the valve will immediately close and the fan will coast to a stop. The resistor 13 will then cool off to the ambient temperature to again increase its resistance so that, upon a second call for heat, by the room thermostat or limit control, a delayed opening of the valve will again result.

Modification While in most cases it is desirable to have a resistor 13 disposed that it will cool off rapidly to its high resistance condition, it is recognized that there may be burner installations which could advantageously use a time delay valve having an initial long time delay followed by a shorter time delay for subsequent energizations of the valve. In such an installation, the modified form of the valve as shown in Figure 4 would be useful. It will be noted that the resistor 13 in this modification is positioned between the coil windings. The. exact position of the resistor 13 in the coil may obviously be varied between a point adjacent the plunger tube 12 and a point at the outermost windings, to provide the characteristics desired. Due to the blanketing effect of the coil and the heat generated by the windings, it will be apparent that the heat loss from the resistor 13 will be much less rapid than in the modification shown in Figures 1 and 2. This will be particularly true in the cooling down cycle of the resistor following deenergization of the valve. Thus, while the initial heating up period for the modification of Figure 4 may be substantially as long as that of Figures 1 and 2, it is deemed apparent that, due to the longer time, required for the heat to be dissipated from the resistor upon a shutdown of the burner apparatus, the room thermostat may make an additional call for heat before the resistor 13 has returned to its normal high resistance condition. Obviously, under these circumstances, less time will be required for the resistor to again heat up sufliciently to enable the valve to open, thus providing a shorter delay period. An example of a burner installation which may make use of the operating characteristics of the modification of Figure 4 may be one wherein natural or convention draft means is provided, in addition to a fan or blower, for supplying primary combustion air to the burner or combustion chamber. As the draft created by a warm furnace is greater than that of a cold furnace, more air would naturally flow into the furnace when hot than when it is cold, to support combustion.

Aside from the difference in the delay action of the resistor of the Figure 4 modification, the valve of said modification would operate in the same general manner as the other valve and be connected in a control circuit identical to that of Figure 3.

While I have described the preferred embodiments of the invention, it will be apparent to those skilled in the art that other variations may be made in the valve without departing from the spirit of the invention. Therefore, it is to be expressly understood that the scope of the invention is to be determined solely from the appended claims.

I claim:

1. A delayed action fuel valve for use in a system where the delivery of fuel is not desired immediately upon energization of the valve motor comprising in combination a valve normally in fuel flow interrupting position, an electric solenoid motor for actuating said valve to a second position in which fuel flow may take place, said motor comprising a solenoid coil therein, a resistor having a negative temperature coefficient of resistance connected in series with said coil and being positioned adjacent to said coil, said resistor being of such resistance value at ambient temperature that upon a current supply of normal voltage being applied to said solenoid coil and resistor the current flowing to said solenoid coil is insuflicient to cause said solenoid motor to actuate said valve from its normal fuel flow interrupting position but after a predetermined time during which current is flowing through said coil and resistor said resistor will become heated to such a temperature above ambient that its resistance will be lowered to a value which permits the coil to be sufliciently energized by the current supply as to cause actuation of said. valve to said second position by said motor so that fuel flow may take place, a heat insulating member interposed between said resistor and said coil so as to reduce the tendency of the resistor to be maintained heated by residual heat in said coil upon de-energization of said resistor and coil and so that the resistor will more quickly reassume a condition in which it delays actuation of said valve by said motor, and a housing enclosing said coil and being of greater volume than said coil so as to accommodate said resistor with the resistor located between said coil and the wall of said housing.

2. A delayed action fuel valve for use in a system where the delivery of fuel is not desired immediately upon energization of the valve motor comprising in combination a valve normally in fuel flow interrupting position, an electric solenoid motor for actuating said valve to a second position in which fuel flow may take place, said motor comprising a solenoid coil therein, a resistor having a negative temperature coefficient of resistance connected in series with said coil and being positioned adjacent to said coil, said resistor being of such resistance value at ambient temperature that upon a current supply of normal voltage being applied to said solenoid coil and resistor the current flowing to said solenoid coil is insufficient to cause said solenoid motor to actuate said valve from its normal fuel flow interrupting position but after a predetermined time during which current is flowing through said coil and resistor said resistor will become heated to such a temperature above ambient that its resistance will be lowered to a value which permits the coil to be sufficiently energized by the current supply as to cause actuation of said valve to said second position by said motor so that fuel flow may take place, a heat insulating member interposed between said resistor and said coil so as to reduce the tendency of the resistor to be maintained heated by residual heat in said coil upon de energization of said resistor and coil and so that the resistor will more quickly reassume a condition in which it delays actuation of said valve by said motor, and a housing enclosing said coil and being of greater volume than said coil and resistor by reason of a portion projecting beyond said coil so as to provide a region within said housing to accommodate said resistor with the resistor located between said coil and the wall of said housing, said region being larger in volume than said resistor to provide air space around said resistor.

References Cited in the file of this patent UNITED STATES PATENTS 788,536 Irving May 2, 1905 921,760 Waterman May 18, 1909 1,627,949 Baker May 10, 1927 2,003,624 Bower June 4, 1935 2,034,311 Rubel .Mar. 17, 1936 2,112,542 Myers Mar. 29, 1938 2,134,900 Ohlsen Nov. 1, 1938 2,282,197 Maynard May 5, 1942 2,735,644 Bishofberger Feb. 21, 1956 OTHER REFERENCES Thermistors in Electronic Circuits; Electronic Industries; January 1945, pp. 76-80. (Copy in Div. 48.)

Relay Engineering, by Charles Packard, Structhers- Dunn Inc. (1945). (Copy in Scientific Library.)