US2967021A - Liquid heating apparatus and control system therefor - Google Patents

Description

an- 3, 1961 P. F. SWENSON mm. 2,967,021

LIQUID HEATING APPARATUS AND CONTROL SYSTEM THEREFOR Filed May 9, 1958 R m m m LIQUID HEATING APPARATUS AND CONTROL SYSTEM THEREFOR Paul F. Swenson, Cleveland Heights, and Myron T.

'Cooperrider, Cleveland, Ohio, assignors to Iron Fireman Manufacturing Co., Cleveland, Ohio, a corporation of Oregon Filed May 9, 1958, Ser. No. 734,336

Claims. (Cl. 2361) This invention relates to a new and improved liquid heating apparatus and particularly to an automatic control system therefore, and is an improvement in the iuvention disclosed in the copending application to Paul F. Swenson and Myron T. Cooperrider, Serial No. 347,048, filed April 6, 1953, now Patent.No. 2,836,365, entitled Steam Generating Apparatus and Controls Therefor.

In the apparatus described in the above-identified c0- pending application, a continuously burning pilot uncontrolled by the control system is employed. The present invention is a modification of the earlier control system by virtue of which the pilot burner itself also is under the control of the thermostatically controlled valve so that, in event of failure of the control valve or the fluid pressure operating means therefor, the pilot will be extinguished along with the main burner.

Heretofore, in hot water heaters, boilers, furnaces, and the like, of this character, the danger of gas explosions due to the continuous supply of gas to the pilot was very remote.

The ordinary illuminating gas customarily used was lighter than air and consequently the small amount of gas supplied to an extinguished pilot would be vented through the usual stack, or if not vented through the stack, would rise in the air and generally leak out of the house with the air at a rate sufficiently great so that the accumulation of any appreciable amount of the illuminating gas or gas and air mixture sufficient to cause explosions was very remote. More recently, however, the gas supplied for water heaters and the like is a liquid petroleum gas which is supplied in tanks usually located on the ground level outside of the house and connected to the feed line system in the house through a throttling valve.

This petroleum gas is heavier than air and consequently, if the pilot becomes extinguished, the escaping petroleum gas tends to settle to the floor level. Since such heaters are usually located in the basement, there is little chance for the gas to escape. Ordinarily, sewer and drain outlets are provided with gooseneck traps which, of course, form a barrier. As a result, the gas will accumulate in the basement to a level which might be from a few inches to several feet. Unless it is accumulated to a considerable elevation so that a person walking in the basement Will cause drafts and eddy currents which will carry the gas upwardly so that it can be detected by its odor, there is a grave danger that a person will unwittingly light a match to relight the burner and,

when the flame is moved to the level of the pilot burner,

- will ignite the large accumulation of the gas or gas-air mixture in the basement. Accordingly, therefore, it is becoming increasingly necessary that some means be provided for stopping the supply of gas to the pilot in event the pilot becomes extinguished and cannot be reignited immediately by the main burner if the latter happens to be operating. 1

In accordance with the present invention, the control of the above copending application is modified so that nited States Patent 0 2,967,021 Patented Jan. 3, 1961 ice it is necessary for igniting the pilot in the first instance to operate a manual valve, but after the pilot is ignited, the supply of fuel thereto is maintained independently of the manual valve so long as the pilot is operating, but is discontinued if the pilot remains inoperative for a very short interval. This is accomplished while retaining the control features of the earlier invention.

Various other objects and advantages of the present invention will become apparent from the following description wherein reference is made to the drawing, in which the drawing is a fragmentary, vertical, sectional view through a heating apparatus and control embodying the principles of the present invention, parts thereof being shown in elevation for clearness in illustration.

Referring to the drawing, the invention is shown in combination with a steam generating system which employs a boiler 1 to which a heating coil 2 is connected, the steam from the heating coil 2 entering the boiler 1 through a conduit 3 which opens above the normal level L of the water in the boiler. A recirculating line 5 leads to the lower end of the coil 2.

In order to heat the coil 2, a suitable main burner 6 is provided. Adjacent the burner 6 is a pilot burner 7 in mutual firing relation thereto. Gas is supplied to the main burner 6 through a suitable gas line 8 and is supplied to the pilot 7 through suitable lines 9 and 10, as will be more fully described hereinafter. The pilot 7 is arranged in heating relation to a bulb 11 of a sealed expansible fluid type of thermostatic device. The bulb 11 is continuously connected by a duct 12 to a bellows 13 and is operative so that, upon heating of the bulb, the

bellows is expanded. In the tank 1, below the liquid level therein so as to be subjected to the heat of the water, is another bulb 14 of the type similar to the bulb 11. The bulb 14 is connected by the duct 15 to the bellows 13 also so that, upon expansion of the fluid in the bulb 14, the bellows is expanded.

The bellows comprises part of a thermostatic valve device indicated generally at 16, into which gas is supplied through a suitable feed line 17. The duct 10, leading to the pilot, is connected to the feed line 17 in advance of the valve device 16. A suitable manual valve 18 is interposed in the line 10 between the feed line 17 and the pilot 7. The valve 18 is provided with a valve plug 19 which is held in normally seated condition by a spring 20 acting through a rod 21. Rod 21, in turn, is provided with a push button 22 which can be depressed manually admitting fuel to the main burner.

As more fully described in our copending application, one end of the bellows 13 is held in fixed position relative to the body 23 of the valve device 16. The other end of the bellows is fixedly connected to a rod 24, the opposite end of which is connected to a spring 25 adjustable by a suitable screw 26 for increasing and decreasing its tension. The spring 25 is arranged to apply tension to the rod 24 so as to urge the bellows in the expanding direction.

Mounted .in surrounding relation to the rod 24 is a sleeve 27 which, at one end, abuts the free end wall of the bellows 13 but is unconnected thereto and is freely movable endwise of the rod 24 and relative to the bellows. Mounted on the rod 24 is an adjustable abutment 28 between which and the lower end of the sleeve 27 is interposed a light spring 29 which yieldably holds the sleeve 27 in a position with its end in abutment with the end of the bellows 13. Mounted on the sleeve 27 is a valve plug 30 which is movable with the sleeve, and thus, in the form illustrated, is moved downwardly upon expansion of the bellows 13 by expansion of the fluid in the bulbsll and'14. The valve device 16 is provided with a pair of spaced seats 31 and 32 which are coaxial with eachother and are spaced apart axially. The seat 31 is the inlet seat and the seat 32 is the outlet seat, so-that fuel supplied through the line 17 passes first through the port of the seat 31 thence through the port of the seat 32 to the main burner supply line 8. The plug 30 is mounted on the sleeve 27 between the seats. The spacing of the seats and the size of the plug 30 are such that when the pilot burner is oif so that the fluid in the bulb 11 is unheated, the bellows will be sufficiently contracted so that the plug 30 will seat on the inlet seat 31 and thus stop the supply of gas to the burner 6. On the other hand, it will open to admit gas through the Port of the seat 31 and to and through the port of the seat 32 when the bulb 11. is heated sutficiently to expand the fluid therein. Thus lighting of the pilot results in introduction of the gas to the main burner 6 around the plug 30. However, as described in the above copending application, it is desired to reduce the flow of gas to the burner 6 through the line 8 if the temperature in the tank reaches a predetermined maximum. As this temperature approaches the maximum, the fluid in the bulb 14 expands and further expands the bellows, thus moving the plug 30 from the intermediate position between the seats toward the seat 32. The plug, however, is not moved to the seat 32 but remains between the seats so that fuel is continuously supplied to the main burner 6. As the temperature further increases and heats the bulb 14, the bellows expands farther and moves the sleeve 27, and with it the plug 30, downwardly, closer to the seat 32, thus gradually reducing the flow of gas to the main burner.

The valve plug 311/ is arranged to be seated on the seat 32 with a snap action. For this purpose, a magnet 33 is mounted in the body 23 for adjustment endwise of the sleeve 27 toward and away from the lower end of the sleeve 27. The magnet is connected to an adjusting screw 34 so that it can be adjusted to preselected positions endwise of the sleeve. The sleeve 27 is magnetic, or at its lower end contains magnetic material, so as to be responsive to the magnet when it approaches closely enough thereto.

When the temperature in the tank, and hence of the. bulb 14, reaches a predetermined maximum value, the.

pressure developed by the bulb 14, added to that of the bulb 11, and assisted by the spring 25, further expands the bellows sufliciently to move the lower end of the sleeve into such close proximity of the magnet 33 that the magnet pulls the sleeve 27 downwardly, overcoming the spring 29, and seats the plug 30 on the seat 32 with a snap-action.

The duct 9 for maintaining the pilot continuously in operation is connected to the interior of the body 23 at a location between the seats 31 and 32. Accordingly, after the pilot is ignited by gas supplied through the duct 10 and'the manually operable valve 18 and heats the bulb 11 sufliciently to lower the plug 30 from the seat 31, the pilot'is maintained thereafter by gas supplied through the inlet port of the seat 31 and the duct 9. It is to be noted that both the ducts 9 and 10 lead to the pilot and each discharges into the atmosphere in the pilot tube through its individual duct so that the ducts 9 and 10 are isolated frplm each other and gas cannot flow from one into the ot er.

Thus, in operation, should the pilot light become extinguished and not immediately reignited by the main burner, then the plug '30 will be moved into seating relation to the seat 31, thus stopping the supply of gas both to the main burner and to the pilot. If, of course, the main burner happens to remain ignited when the pilot is extinguished, the pilot is immediately reignited, by the main burner.

If desired, the valve plug 30 may be secured to the sleeve for slight rocking movement as described in the copending application above identified, but it is held in fixed position-relative to the sleeve 27 endwise or axially of the sleeve.

Upon full contraction of the bellows 13, the spring 25 is overcome by virtue of the pull on the rod 24 so that the seating spring 29 is operative for lifting the sleeve 27 and plug 30 to cause the plug '30 to seat on the seat 31.

Further, if desired, the duct 9 which supplies the pilot may be connected to the pilot through a suitable cutoff valve 35 which is operated by a push button 35a and floatoperated lever 36. A float 37, for operating the lever 36, is provided. The float also operates a normal water supply valve 38 in a water supply line 39, for admitting replacement water to the boiler 1, when the water level falls too low. The float is arranged within the boiler 1 and is operative when the level of the-water in the boiler is reduced beyond a predetermined minimum to operate the button 35a and close the valve 35, thus cutting off the pilot, whereupon the control valve device operates to stop the supply of fuel to both the pilot and the main burner.

In this manner, the dangers of overheating, due to low water in the boiler, are eliminated.

In order that the device fail safe in event a leak occurs in the bulb and bellows system while the pilot is extinguished, the bellows and bulb system used is preferably one in which the internal pressure, when the system is originally charged and sealed, is sub-atmospheric and so remains until predetermined heating of the bulbs and expansion of the fluid develops a positive pressure therein. The contractive force of the bellows, tending to lift the valve plug 30,. is due to the inherent resilient resistance of the bellows to elongation and the resultant self-restoring force, plus the sub-atmospheric pressure in the system.

The spring 25 is made adjustable in tension to vary the temperature at which the valve is opened and closed by the bellows, but so that in all adjusted conditions of operation it has suflicient tension to overcome the inherent resistance to elongation of the bellows alone, when the bellows is unrestrained by sub-atmospheric pressure in the lines 12 and 15, to a degree necessary to move the lower end of the sleeve close enough to the magnet to cause the magnet to snap the plug 30 into closed seated position on the seat 32.

Consequently, should a leak occur in the bulb and bellows. system so that only the inherent self-restoring force of the bellows resists the expansion of the bellows by the spring 25, the spring 25' will move the sleeve sufliciently close to the magnet 33 so that the magnet will seat the plug 30 on the seat'32 and thus cut ofi the supply of fuel to the main burner.

However, should the pilot be, or become, extinguished during the failure caused by a leak in the bulb and bellows system, fuel would still pass-to the pilot through the seat 31, except for the fail safe now to be described.

When the lower end of the sleeve 27 is moved by the spring 25close enough to the magnet 33 so that the sleeve comes under the influence of the magnet and is drawn, with a snap action, toward and by the magnet, the upper end of the sleeve is moved downwardly away from the lower end of the bellows 13, thus establishing a clearance space between the lower end of the bellows 13 and the upper end of the sleeve 27. Thus, in event a leak develops in the bulb and bellows system so that the subatmospheric pressure'is relieved, the spring 25 can elongate the' bellows additionally even though the plug 30 is seated on the seat 32. Since there is a leak in the system, the spring 25 continues elongating the bellows in a direction to reduce the clearance between the upper end of the sleeve 27 and lower end of the bellows 13. Normally, this action would continue until the bellows were again engaged with the upper end of the sleeve, at which point. further movement would be arrested due to the valve plug 30' being seated on the seat 32.

To render the system fail safe under such conditions, therefore, a valve plug 40 is fixedly connected to the bottom of the bellows for movement therewith. The plug 40 is preferably of somewhat greater diameter than the plug 30 and the ports of the seats 31 and 32 so that, even though it is only slightly open, a relatively large annular passage for gas is provided between it and the seat 31. The lower edge or seating area of the valve plug 40 is positioned axially of the seats so that it can engage and seal on the seat 31 before the clearance between the lower end of the bellows 13 and the upper end of the sleeve 27, when the sleeve 27 is held by the magnet 33 in the downward position with the valve 30 seated on the seat 32, is eliminated. Accordingly, therefore, a leak in the fluid pressure system, resulting in failure of its operation, causes a closure of the valve plug 40 on the top of the seat 31 and stops the flow of fuel to the pilot as well as to the main burner.

It is apparent from the foregoing description that the device is one which is arranged to fail-safe in all instances and furthermore, upon failure of the system for any reason or upon extinguishing the pilot without its immediate reignition, not only is the supply of fuel to the main burner discontinued, but also the supply of fuel to the pilot is discontinued, thus eliminating the very serious explosive hazard due to the use of heavier than air fuels.

It is to be noted that, in the case of fuel oils, this hazard still exists as fuel oil escaping in a basement can cause fumes which can become explosive.

Further, it is to be noted that these hazards are increasing due to the fact that quite often automatic and other furnaces are provided which, at any time, may cause ignition of the accumulated gases.

Having thus described our invention, we claim:

1. A fluid fuel control valve for controlling the flow of fuel to a heating apparatus containing a liquid to be heated and having a main and a pilot burner, said valve comprising a housing with a fluid fuel inlet port adapted to be connected to an associated fuel source and a fluid fuel outlet port connected to the main burner, said housing containing an annular inlet seat and an annular outlet seat coaxial with said inlet seat and spaced therefrom in a direction nearer the valve outlet port in the direction of flow of fluid through the valve from its inlet port to its outlet port, a fluid motor means disposed above said inlet seat and having a movable wall displaceable toward and .away from the inlet seat in response to pressure changes interiorly of the motor means, thermo-responsive bulb elements adapted to be disposed in heat association with the pilot burner and with the liquid to be heated, means forming a confined fluid column respectively connecting said bulb elements, said bulb elements and confined columns being initially charged and sealed with a thermo-responsive fluid at sub-atmospheric pressure whereby subsequent vapor pressure developed in both of the bulb elements by heating the elements is transmitted by the confined columns to the interior of the motor means, a pilot duct adapted to connect the interior of the valve at a location between the seats with the pilot burner, a pilot by-pass duct adapted to connect the pilot burner with the associated fuel source, a normally closed valve in the by-pass duct and operable to be opened for admitting fluid fuel to the pilot burner, a rod secured to said movable wall for movement therewith and extending through and beyond said seats, a sleeve member slidably telescoped onto said rod with the upper end of the sleeve disposed immediately adjacent said wall and movable axially relative thereto, a valve plug secured on said sleeve at a point intermediate the seats, said valve plug being movable with the sleeve in opposite directions for fluid sealing cooperation with the seats, respectively, resilient means compression connected to the lower end of the sleeve for urging said sleeve toward said wall in a manner to normally seat the valve plug on the inlet seat when pressure is not being supplied to the motor means by the bulb elements, supplemental valve closing means disposed at a, preselected distance below the lower end of the sleeve and operable upon a predetermined approach of the valve plug toward the outlet seat to move the sleeve relative to, and away from, the motor means, and thereby to move the valve plug into seating relation with the outlet seat against the force of said resilient means, whereby the upper end of the sleeve is spaced from said wall and the motor means may expand further, and a safety valve plug secured to the lower side of said wall and movable with the wall toward and into seating relation with the inlet seat upon said further expansion of the motor means after the first-named valve plug is seated on the outlet seat.

2. A fluid control valve according to claim 1 wherein the pilot by-pass duct is uncommunicated with the pilot duct between said valve housing and the point of connection of the pilot duct with the pilot burner.

3. A fluid control valve according to claim 1 wherein said fluid motor means is a pressure-responsive bellows axially elongatable in response to pressures applied interiorly thereof.

4. A fluid control valve according to claim 1 having a second resilient means tensionally secured to the lower end of said rod for supplementing the expanding action of the motor means.

5. A fluid control valve according to claim 1 wherein said supplemental valve closing means is a permanent magnet rigidly disposed below the lower end of the sleeve for drawing the sleeve downwardly out of contact with the said wall with a snap action and thereby sealingly seating the first-mentioned valve plug on the outlet seat.

References Cited in the file of this patent UNITED STATES PATENTS

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