US3072337A

US3072337A - Top burner control for gas ranges

Info

Publication number: US3072337A
Application number: US861810A
Authority: US
Inventors: Richard D Grayson
Original assignee: General Controls Co
Current assignee: General Controls Co
Priority date: 1959-12-24
Filing date: 1959-12-24
Publication date: 1963-01-08
Anticipated expiration: 1980-01-08

Description

Jan. 8, 1963 R. D. GRAYSON TOP BURNER CONTROL FOR GAS RANGES Filed Dec. 24, 1959 /numnumuunnnnumuu /0E United States Patent ()fiiice 3,@7Z,337 Patented Jan. 8, 1953 31,672,337 Th? BURNER PJTRL FQR GAS RANGES Richard D. Grayson, La Canada, Caliih, assignor to General (Jontrols a., Glendale, Qalifi, a corporation of Filed Dec. 24, 195% Ser. No. 361,310 3 Claims. (til. Z36-32) The present invention relates generally to a thermostatically controlled valve and particularly one which controls the flow of gas to the top burner of a gas stove having a heat-sensing element in contact with a cooking utensil on such burner although in its broader aspects the present invention is applicable to other gas-controlled heating systems such as, for example, room heater controls and the like.

One of the main problems encountered in a top burner thermostatic control arises from the fact that a relatively small gas flow must be controlled to maintain a constant temperature of, for example, 200 F. in a small cooking vessel on the burner, such gas flow being usually less than a flow of 800 B.t.u. below which the burner flame tends to flutter and become extinguished.

Previous attempts have been made to solve this problem by modulating the burner from an On condition to an Off condition, ie in the range between 800 Btu. and O B.t.u., while maintaining a small stand-by pilot flame adjacent to the burner ports. As the gas flow is modulated up and down in the range between 800 and 31.11., the burner operation is erratic and raw gas is usually released, resulting in an objectionable gas odor due, for example, to the aldehydes therein which have a distinct and powerful odor. This condition may also lead to flash back with the gas igniting at the burner orifice and further to additional combustion problems resulting from the loss of gas velocity at the orifice at very low inputs due to throttling of the gas upstream from the orifice.

In accordance with an important feature of the present invention, a single valve is used to accomplish both a modulating and snap-controlling action. lnaccordance with prior art practice two valves are provided, i.e. a modulating valve for operating between minimum and maximum flame, and a second snap valve for snapping off the minimum flame.

Such single valve, in accordance with features of the present invention, is temporarily restrained from further closing movement when the minimum flame position has been reached; and further increase in temperature caused by gas escaping in such minimum flame position causes a build-up of forces which eventually overpower the restraining member. As soon as the restraining member starts to yield, there is sufficient stored energy in the various resilient portions of the mechanism to cause the valve to snap to the closed position. Subsequently, as the temperature drops, the closing forces relax to the point where the magnet is capable of abruptly opening the valve to the minimum flame position.

It is therefore an object of the present invention to provide an improved control system of this character which overcomes the above-indicated difficulties encountered in the prior art arrangements.

A specific object of the present invention is to provide an improved system of this character in which a thermo statically controlled valve is incorporated featured by the fact that substantially full velocity of the orifice stream is maintained at all inputs.

Another object of the present invention is to provide a control system of the type indicated in the preceding paragraph in which the valve is a needle valve or a valve similar to a needle valve.

Another object of the present invention is to provide a valve arrangement of this character in which a modulating control action and a snap closing action are obtained using a single needle valve or a single valve similar to a needle valve.

Another object of the present invention is to provide an improved thermostatically operated valve which is particularly useful in a system of this character.

Another object of the present invention is to provide a gas control of this character in which the flow of gas is continuously modulated from a predetermined maximum rate to a predetermined minimum rate and in which the flow of gas is abruptly shut off when the demand for gas tends to fall below such predetermined minimum rate.

Another object of the present invention is to provide a control of the character set forth in the preceding paragraph in which adjustable means are provided for adjusting such predetermined maximum rate.

Another object of the present invention is to provide a gas control of the character set forth in the two preceding paragraphs in which the flow velocity of gas passing through the outlet orifice is a substantially constant value during its modulation in the range between such maximum and minimum values.

Another object of the present invention is to provide an improved gas control of this character for a burner having associated therewith a venturi section for inspirating air, the control being characterized by a single movable valve element for continuously modulating the flow of gas into such venturi section at a substantially constant speed within the range of continuous modulation.

Another object of the present invention is to provide a control as set forth in the preceding paragraph in which such single movable valve element is operated to a closed position with a snap action when the demand for gas falls below a predetermined minimum rate.

Another object of the present invention is to provide a gas control of this character for maintaining a substantially constant temperature in the vicinity of a gas burner, there being provided for this purpose thermostatic means responsive to temperature in the burner for continuously modulating the rate of gas flow between a maximum and a minimum value with such thermostatic means functioning also to cause the valve to snap to closed position when the demand for gas tends to fall below such minimum value.

Another object of the present invention is to provide a gas control of this character which incorporates adjustable means for establishing such substantially constant temperature.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organization and manner of operation, together with further objectsand advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

FIGURE 1 illustrates a top burner control system incorporating features of the present invention' FIGURE 2 illustrates more details of the thermostatically operated valve shown in FIGURE 1.

in FIGURE 1 there is illustrated a top burner 19 for a conventional household cooking stove which incorporates, in conventional manner, a centrally positioned spring-biased temperature-sensing element ill for contacting and sensing the temperature of the bottom of a cooking vessel (not shown) resting on such burner.

Also associated with such burner litl is a small pilot burner (not shown) which is continuously ignited to as sure burning of all of the gas controlled by the valve structure l2 constructed and functioning novelly in accordance with important features of the present invention.

This valve structure indicated generally at 12 in FIG- URE 1 involves a movable needle valve element 13 cooperating with its fixed valve seat 14 for controlling the flow of gas into the air-gas mixing chamber 15 leading to the venturi section 16 and the burning ports of burner lit. The flow of air may be controlled by an adjustable shutter 13 surrounding the chamber 15.

As the gas flow is reduced by forward movement of the needle valve element 13 in its orifice 14, substantially full velocity of the gas stream through such orifice is maintained, assuring proper air inspiration and optimum flame characteristics at reduced B.t.u. inputs. This needle valve element 13 is controlled thermostatically in response to the temperature sensed by the sensing element 11.

The orifice 14 is mounted in the valve body 2%) in such a way that it injects a gas stream directly into the burner venturi tube ltd, the gas being introduced into the chamber 2%? through its threaded opening 21 which is in communication with the gas manifold 22 (FIGURE 1).

The stem of needle valve element 13 is guided in guide fins 24 which, of course, allow gas flow to the orifice 1d and such element 13 is actuated by lever 25.

Lever 25 has one of its ends bearing on an adjustable stem or abutment 26 threaded in housing 2t} and the prestressed coil compression spring 29 acting between the housing 2 and an intermediate portion of lever 25 presses the same into engagement with both the stem 26 and the movable lever seat 27 Which is positioned between lever 25 and the movable end of expansible bellows 28.

Bellows 28 is expanded in increased amounts with increasing temperatures sensed by element 11 and details of the same may follow conventional practices in which a capillary tube 3t) filled with a suitable fluid extends between the sensing element 11 and bellows 28.

It will thus be seen that upon increase in temperature the lever 25 is pivoted counterclockwise (FIGURE 2) about the adjustable abutment 26. The needle valve element 13 follows such movement of lever 25 since the lower flanged portion 13A of valve 13 is pressed into engagement with one end of lever 25 by the coil compression spring 133 acting between element 13 and a threaded portion of housing 20.

The lever 25 also under certain conditions is movable into engagement with the free end of the cantilever-supported lever 32 to move it out of its normally attracted position by magnet 36. Lever 32 is of magnetizable material, has one of its ends anchored at 34 on the housing Ztl, and is normally held in attracted position by permanent magnet 36 on housing 2t against the lower housing stop member 38.

In operation of the arrangement shown in FIGURE 2, it is initially assumed that the sensing element 11 is in a cold but preheated condition, i.e. it calls for heat and the parts are in the positions illustrated. It is noted that in the extreme cold condition of element 11 the bellows 28 is deflated and the movement of lever 25 and needle valve element 13 is arrested by the threaded stem 41 of adjustable knob 40 which is preadjusted to establish the maximum burner flame, i.e. the maximum opening between valve element 13 and its orifice 14. As the temperature of the sensing element 11 rises, the bellows 28 expands, however, still allowing the fiow of gas through orifice 14 at substantially the same velocity but in smaller quantity, i.e. smaller B.t.u. rate. As the temperature of element 11 increases further, the lever 25 is moved into engagement with the free end of the magnetically attracted lever 32 which then serves as a temporary stop for further movement of lever 25 and the valve element 13. Upon substantial further increase in temperature, the force of attraction between the temporary stop 38 and magnet 36 is overcome and the lever 32 is then free to move to allow the valve element 13 to snap into closing position in its orifice 14 to prevent further flow of gas. A second permanent housing stop 24A may be provided i to limit upward movement of lever 32 to a position wherein it may be again attracted upon subsequent deflation of bellows 28, in which case the

valve

13, 14 is opened with a snap action.

The lever 32 thus acts as a temporary stop or abutment at a predetermined gas flow rate corresponding to, for example, 880 Btu. and should the sensing element still continue to call for a smaller rate of gas flow, the

valve

13, 14 is closed with a snap action to allow the heated vessel and sensing element to cool to a temperature at which the

valve

13, 14 is reopened with a snap action resulting from the quick movement of the lever 32 back to its attracted position. In other words, flow of gas at rates less than 860 Btu is prevented but when the required input exceeds 890 B.t.u., the valve element 1 3 modulates between a full open position, established by stem 51, and the 800 B.t.u. position established by the temporary stop lever 32.

It will be noted further that the temperature at which such snap action of the

valve

13, 14 occurs may be adjusted by adjustment knob 26A, movement of the stem 26 outwardly in the housing 29 serving to establish a lower operating temperature which is maintained substantially constant in the manner described above with the

valve

13, 14 being periodically snapped to closed and open position. Conversely, movement of the stem inwardly results in maintenance of a higher operating temperature which may be sufficiently high to permit maintenance of a substantially constant temperature without any snap action, i.e. by modulation alone between positions corresponding to stem 4-1 and the at tracted position of lever 32.

While the drawings show my preferred form of a pointed needle valve cooperating with a mating tapered orifice, the form of the valve may be different, i.e. it may comprise a small diameter rod projecting in varying degrees in a circular seat with, for example, a flange on the rod cooperating with an adjacent circular seat for full closure of the valve.

Although the drawings show a magnet 36 for accomplishing the above-described purposes, it is understood that other biasing means having a negative spring rate may be substituted therefor. Further, instead of a needle valve as shown in the drawings, a small diameter poppet valve could be substituted for the same.

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. In means forming an orifice, a gas control system, a burner, a single movable valve element in communication with said burner and cooperating with said orifice to continuously control the flow of gas through said orifice to said burner over a range extending from a maximum rate to a minimum rate which is substantially greater than a Zero rate, an abutment, valve element moving means comprising a lever having one of its ends engageable with said valve element and the other one of its ends engaging said abutment, thermostatic 'means associated with said burner and responsive to temperature at said burner and engaging an intermediate portion of said lever, spring means acting On said lever at a point thereon between said abutment and said intermediate portion to bias said valve element away from said orifice, said thermostatic means moving said valve element towards valve closing position upon rise in said temperature condition, temporary abutment means for temporarily preventing movement of said valve element to its fully closed position after said thermostatic means mOVes said valve element to a position corresponding to said minimum rate, means as sociated with said temporary abutment means and operated by said thermostatic means for disabling said temporary abutment means when said temperature condition assumes a predetermined maximum temperature value.

2. A control as set forth in claim 1 in which the first mentioned abutment is adjustable to pivot said lever and move said valve element with respect to said orifice to adjust said predetermined maximum temperature value.

3. A control as set forth in claim 1 in which an adjustment abutable abutment is in the path of movement of 15 said lever for engagement therewith to limit movement of said valve element to adjust said maximum rate.

References Cited in the file of this patent UNITED STATES PATENTS 1,412,773 Colgate Apr. 11, 1922 1,875,511 Shivers Sept. 6, 1932 2,480,757 Mitchell Aug. 30, 1949 2,719,673 McCarty et al. Oct. 4, 1955 2,767,923 Matthews Oct. 23, 1956 2,884,009 Hetherington Apr. 28, 1959 FOREIGN PATENTS 789,638 Great Britain Jan. 22, 1958

Claims

1. IN MEANS FORMING AN ORIFICE, A GAS CONTROL SYSTEM, A BURNER, A SINGLE MOVABLE VALVE ELEMENT IN COMMUNICATION WITH SAID BURNER AND COOPERATING WITH SAID ORIFICE TO CONTINUOUSLY CONTROL THE FLOW OF GAS THROUGH SAID ORIFICE TO SAID BURNER OVER A RANGE EXTENDING FROM A MAXIMUM RATE TO A MINIMUM RATE WHICH IS SUBSTANTIALLY GREATER THAN A ZERO RATE, AN ABUTMENT, VALVE ELEMENT MOVING MEANS COMPRISING A LEVER HAVING ONE OF ITS ENDS ENGAGEABLE WITH SAID VALVE ELEMENT AND THE OTHER ONE OF ITS ENDS ENGAGING SAID ABUTMENT, THERMOSTATIC MEANS ASSOCIATED WITH SAID BURNER AND RESPONSIVE TO TEMPERATURE AT SAID BURNER AND ENGAGING AN INTERMEDIATE PORTION OF SAID LEVER, SPRING MEANS ACTING ON SAID LEVER AT A POINT THEREON BETWEEN SAID ABUTMENT AND SAID INTERMEDIATE PORTION TO BIAS SAID VALVE ELEMENT AWAY FROM SAID ORIFICE, SAID THERMOSTATIC MEANS MOVING SAID VALVE ELEMENT TOWARDS VALVE CLOSING POSITION UPON RISE IN SAID TEMPERATURE CONDITION, TEMPORARY ABUTMENT MEANS FOR TEMPORARILY PREVENTING MOVEMENT OF SAID VALVE ELEMENT TO ITS FULLY CLOSED POSITION AFTER SAID THERMOSTATIC MEANS MOVES SAID VALVE ELEMENT TO A POSITION CORRESPONDING TO SAID MINIMUM RATE, MEANS ASSOCIATED WITH SAID TEMPORARY ABUTMENT MEANS AND OPERATED BY SAID THERMOSTATIC MEANS FOR DISABLING SAID TEMPORARY ABUTMENT MEANS WHEN SAID TEMPERATURE CONDITION ASSUMES A PREDETERMINED MAXIMUM TEMPERATURE VALUE.