US1881949A - Control for oil burners - Google Patents

Description

Oct. 11, 1932.

c. L. RAYFIELD 1,881,949

CONTROL FOR OIL BURNERS Original Filed Dec. 29, 1927 5 Sheets-Sheet l IE1 ar/es fl g 661d by PQIYE Oct. 11, 1932. c. L. RAYFIELD 1,881,949

CONTROL FOR OIL BURNERS Original Filed Dec. 29, 1927 3 Sheets-Sheet 2 B 91 H k Oct. 11, 1932.

C. L. RAYFJELD CONTROL FOR OIL BURNERS Original Filed Dec. 29, 1927 3 Sheets-Sheet 3 7/4 \MMHWWI ??1 5 11 i 11.?

Patented Oct. 11, 1932 UNITED STATES PATENT OFFICE CHARLES L. RAYFIELD, OF CHICAGO, ILLINOIS, ASSIGNOR TO RAYFIELD MANUFACTUR- ING 00., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS CONTROL FOR OIL BURNERS Application filed December 29, 1927, Serial No. 243,361.

My invention pertains to a control for an oil burner and more particularly to a thermostatically operated mercury switch construction for controlling the operation of an oil burner.

The present invention relates to an oil burner of the same general character as that disclosed in my copending patent application? Serial No. 219,652, filed September 15, 192

I propose in accordance with the features of my invention to provide a novel oil burner control adapted to automatically shut off the supply of fuel should the jet of fuel being projected in the furnace fail to ignite or should it go out after it has once been ignited and also adapted to automatically disconnect the spark unit from the operating circuit once the jet of fuel has been ignited or to again automatically impose it in the circuit shouldthe burner go out.

An object of my invention is the provision of an improved thermostatically operated oil burner control.

Another object of the invention is to provide a novel heat sensitive control for a mercury switch adapted to control the operation of the oil burner motor.

Other objects and advantages of the present invention will more fully appear from the following detailed description taken in connection with the accompanying drawings which illustrate a single embodiment thereof and in which:

Figure 1 is a view of an oil burner partly in section showing the manner in which my novel control is applied thereto;

Figure 2 is a diagrammatic view illustrating the electrical connections of my novel.

Renewed J'anuagy 18, 1932.

Figure 6 is a fragmentary vertical sectional view taken on substantially the line VI-VI of Figure 4 looking upwardly;

Figure 7 is a fragmentary sectional view taken on substantially the line VII-VII of Figure 4 looking in the direction indicated by the arrows; and

Figure 8 is a fragmentary sectional view taken on substantially the line VIII-VIII of Figure 4 looking in the direction indicated by the arrows.

In the drawings:

Like reference characters designate SIIXLlF lar parts throughout the several views.

In Figure 1 it will be observed that the reference character 10 designates generally an oil burner including a discharge nozzle 11 extending into a furnace 12. 'The burner 10 also includes an operating motor 13 and is mounted upon a bench or table 14. Associated with the oil burner 10 and mounted above the table 14 is a control mechanism 15 embodying the features of the present invention. This control mechanism 15 includes a switch box 16, a furnace thermostat 17 positioned within the furnace above the nozzle 11, and a flexible shaft 18 connected to the thermostat 17 and extending into the switch box 16.

The switch box 16 includes a cover 19 (Figure 1) and a base 20 (Figure 3). In Figure 3 the base 20 of the switch box is clearly shown and the cover 19 is omitted in order to show the switch mechanism mounted upon the base 20. The base 20 may be attached in any suitable manner to the housing of the oil burner 10 as shown in Fi re 1.

The thermostat 17 and the flexible shaft 18 connected thereto are of the same construction as that disclosed in my copending patent application Serial No. 219,651, filed September 15, 1927. This thermostat 17 includes a spiral strip 21 of thermostatic metal having a shape similar to that of a clock spring. The inner end 22 (Figure 5) of this strip 21 1s connected to one end of the flexible shaft 18. The outer end of this strip 21 is connected at 23 to an extension 24 formed integral with the housing member 25 which includes a dent that the flexible shaft 18 housed in a flexible conduit 27. 'The, other endjof the flexible shaft 18 extends into the switch box 16 through a suitable opening in the cover 19 the shaft 18- (Figures 4 and 8) adjacent the bracket 28 are a pair of complementary blocks 31 and 32 each of which has an arcuate groove 33 and 34. The two grooves 33 and 34 are disposed directly opposite each other and are adapted to have fitted inthem the shaft 18 (Figure 8). ,The block 32 may be made of any suitable insulation and j is resiliently clamped to the shaft 18" and to the block 31 by means of a bolt 35, a. nut 36 threaded on an end of the bolt, and-a spring 37 positioned between the nut andthe block 32. It will be observed fromFigure 8 that the bolt 35 extends clear through the blocks 32 and. 33. Obviously, by adjusting. the nut- 36 on the bolt 35 it is possible'to vary the tension on the spring 37, thus varying thepressure of the block 32 on the block Y31 and varying the gripping action ofthe'se blocks on the shaft The block 31 has formed integral with it a lateral extending arm 38 which is positioned adjacent the bracket 28, as best shown in Figures 4 and 8.v The free end of this arm extends between the ears 3939 of a U- shaped member 40 secured to base 20. The legs 39'39 of this member 40 carry adjusting screws 41 the-inner ends of which are adapted to-contact the. arm 38 to limit its travel. Obviously, by adjusting the position of the adjusting screws 41-41, it-is possible to vary the distance which the arm 38 can travel. Attention is directed to the fact that when the arm 38 strikes either of thesescrews the block 31 can no longer travel with the shaft 18 should the shaft continue to rotate. Now, due to the factthat the two blocks 31 and 32 are resiliently clamped to the shaft 18, it will necessarily follow that after the arm 38 has struck either of the sorews'41 the shaft 18 can continue to turn independently of the blocks. This is desirable for the reason that should the thermostatic strip 21 continue to expand after the arm 38 of the block 31 has moved as far as the stop screw will permit, the shaft 18 may turn with the thermostat, thus preventing the thermostatic coil from being subjected to undue strains and stresses which would tend to distort it.

Also formed integral with the block 31 is a lateral extending arm 42 (Figures 3 and 4) which projects in a direction opposite to that of the arm 38. This arm 42 is formed inte-- gral with one end of the block 31 whereas the other arm 38 is formed integral with the other end of the block. Threaded into the free .end of the arm 42 is an adjusting screw 43 including a lock nut 44 threaded on an intermediate portion of the screw. The purpose of this adjusting screw will be more fully explained hereinafter.

Secured to the top of the block 31 is a plate 45 igure 8) which has formed integral with 1t a pair of spaced U-shaped clips 46-46. These clips are adapted to resiliently embrace the wall of the cylindrical lass tube 48 which is hermetically sealed at both ends. The tube 48 contains a quantity of mercury 49. Positioned within the tube 48 and disposed concentric with it is an inner glass tube 50 both ends of which are formed open. This inner glass tube is spaced from the inner wall of the tube 48 by means of a ring of insulating material 51 which may be composed of asbestos or any other suitable material. This ring, as shown in Figure 8, is positioned between the ends of the tubes and surrounds an intermediate portion of the inner glass tube 50.

Extending into one end of the tube 48 is a contact element 52 disposed in contact with the body of mercury 49. Extending into the other end of the tube 48 is a contact element 53 disposed in contact with another mass of mercury 54. Also, it will be noted thata bent contact element 55 extends into the top of the tube 48 and through an opening 56 in the inner tube 50 into the bore of this latter tube. The element 55 is at all times disposed in contact with the mass of mercury 49. When the tube 48 is in the position shown in Figure tion of the tube48 is that shown in Figure 8.

This tube is tipped to its other position when the shaft 18 is turned by the thermostatic strip 21.

In Figures 3 and 4 it will be observed that the tube 48 is properly spaced from the bracket 28 by means of a spacing sleeve 57' surrounding the portion of the shaft 18 in- I termediate the bracket 28 and the blocks 31 and 32. Also mounted upon the shaft 18 (Figure 7 is a solid metallic block 58 whichis spaced from the blocks 31 and 32 by means of a spacing sleeve 59 (Figures 3 and 4) surrounding an intermediate portion of the shaft 18. This block 58 has mounted upon it a glass tube 60 which, as will be more fully described hereinafter, houses a motor control switch. The block 58 is spaced from the bracket 29 by means of a spacing sleeve 61 (Figures 3 and 4).

Secured to the top of the block 58 is a plate 66 which has formed integral with it a pair of U-shaped clips 67 (Figure 7) adapted to resiliently embrace the glass tube 60. It is, of course, to be understood that the block 58 is loosely mounted upon the shaft 18 whereas the blocks 31 and 32 are resiliently clamped to the shaft so as to rotate therewith. The shaft 18 extends through one end of the clock 58 whereby the other end of the block is allowed to serve as a counterweight for tipping the tube, as will be more fully explained hereinafter.

Mounted within the glass tube is an inner glass tube 68 spaced from the inner wall of the outer tube by means of an insulating washer 69 which may be made of asbestos or any other suitable insulating material. Both ends of the tube 60 are hermetically sealed whereas both ends of the inner glass tube 68 are formed open. Extending-into the ends of the tube 60 are a pair of contact elements 71 and 72 adapted to contact through a body of mercury 70 disposed in the tubes. When the tube 60 is tipped to the position shown in Figure 7 the two contacts 71 and 72 will be electrically connected by the mercury 70. On the other hand, when the tube 60 is tipped to its other position the mercury 70 will flow into the other end of the tube 60 through the inner glass tube 68. In. this latter position the insulating washer 69 serves to separate the mercury into two separate bodies as is well-known to those familiar with this type of mercury switch. I

Formed inte ral with the block is an extension or arm 3 which projects in the path of a plunger 74 extending through an opening 75 in base 20 (Figure 7). This plunger is rigidly fastened to one end of a collapsible bellows 76 positioned in a casing 77 disposed on the outer side of the base 20. Secured to the casing 77 and surrounding a portion of the plunger 74 is a nipple 78 threaded into the opening 75. A. small sleeve 79 is threaded into the nipple 78 and surrounds the plunger 74, as shown in Figure 7. The other end of the bellows 76 has secured to it a small section of tubing 80 which extends outwardly through, an opening in the casing 77. A nipple 82 surrounds this tubing 80 and is preferably threaded so as to enable it to be connected to a suitable air line such as the source of compressed air used in connection with the conventional type of oil burner.

Now, when the pressure in the air system connected to the bellows 76 reaches a predetermined degree the plunger 7 4 will be pro-. jected into the path of the arm 73 whereby the tube 60 will be held in the position shown in Figure 7. When in this position the contacts 71 and 72 are electrically connected ghrough the means of the body of mercury The block 58 also has formed integral with it a lateral extending arm 83 (Figures 3 and 4) positioned over the arm 42 of block 31. This arm is adapted to-be engaged by the screw 43 of arm 42 previously described. Obviously, if the arm 42 is moved upwardly through the movement of the block 31 by shaft 18 it must necessarily follow that when the screw 43 strikes the arm 83 the tube will be tilted about the axis of shaft 18. tilted position of the tube 60 is shown in Figure 7 and is the position in which the tube is in at the time the burneris set in operation. This screw adjustment permits the tube 48, which is the spark control tube, to operate slightly ahead of tube 60, which is a motor control tube, so that the spark ignition will be on when the motor starts. The counterweight block 58 is adapted to move the tube 60 downwardly should the plunger 74 be moved out of the path of its arm 73.

Connected to the base 20 is a pivot pin 85 upon which is pivotally mounted a lever-like member 86. Rigidly fastened to this member 86 is a plate 87 which has formed integral with it a pair of U-shaped clips 88 ada ted to receive and embrace a glass tube 90. ISO mounted upon the member 86 and extending through the U-shaped clips 8888 is a tube 91 secured at its ends by means of bolts 92 to the ends of member 86. Disposed in this tube 91 are a plurality of balls 93. These ballsare held within the tube bymeans of the bolts 92 which extend through the ends of the tube and thus constitute closures for the ends of the tube. These balls insure that the member 86 is maintained in one or the other of its extreme two tilted positions.

The glass tube is hermetically sealed at both ends and has extending into it a pair of contact elements 94 and 95. Disposed within the glass tube 90 is an inner glass tube 96 having both of its ends formed open. This inner tube 96 is spaced from the outer tube by means of a washer 97 made of asbestos or other suitable insulating material. Disposed This within the tube are two bodies of mercury 1 89 and 98. These bodies of mercury are shown in Figure 6 as being held out of con tact by means of the washer 97. However, it is to be understood that when the tube 90 is in its normal tilted position, which is the reverse of that shown in Figure 6, the contacts 94 and will be electrically connected the tube 90. The other end of the member 86 is adapted when the member is tilted to its reverse position from that-shown in Figure 6 to strike a stop pin 102 secured to the base 20.

Also connected to the base is a pivot pin 103 upon which is pivotally mounted an angular member 104 including a vertical leg 105 and a horizontal leg 106. Secured to the leg 106 is one end of a thermostatic strip of metal 107. The other end of this strip has secured to it a vertical stud 108 adapted when the thermostatic strip 107 expands to strike the end of the member 86 adjacent pin 102 and to thus move the member 86 and the tube 90 to the tilted position shown in Figure 6.

Secured to an intermediate portion of the strip 107 by means of a bolt and nut 109 is an electrical resistance coil 110 which, as

will be more fully explained hereinafter, is connected to the spark control tube 48.

The other leg 105 of member 104 has s e cured to it one end of a thermostatic strip 111 the upper end of which is forked as indicated at 112 so as to straddle the shank of an adjusting bolt 113 which is threaded into a lug 114 formed integral with base 20. The

bi u

rcated end 112 of strip 111 is disposed between tlTe' head 115 of the bolt and a shoulder 116 formed integral with the bolt. This strip 111 is responsive to changes in atmospheric temperature and is adapted to expand in a reversed direction tothat of the strip 107 whereby compensation is made for any variation in room temperature.

Secured to the front of the base 20 is a terminal strip 120 to which are fastened eight terminals 121, 122, 123, 124, 125, 126 127, and 128 (Figure 3). I shall now proceed to describe in detail the circuit associated with my novel control mechanism.

In Figure 2, in order to simplify the explanation ofv the present invention, I have illustrated the circuit and the parts connected thereto in a. diagrammatic manner.

Connected to the terminals 121 and 122 are power leads 129 and 130 which may be connected to any suitable source, such, for example, as a 110 volt line. The terminal 121 is also connected by a wire 131 to-one end of the resistance coil 110. The other end of the resistance coil 110 is connected by a con,-

' ductor 132"to the terminal 123. The contact 94 of tube 90 is connected by a conductor 133 to terminal 122. The contact 95 of tube 90 is connected to terminal 124 by means of conductorv 134. The terminal 121 is also connected to the terminal 128 by means of a strap wire 135.

The motor 13' of the oil burner is connected to the terminals 123 and 125'by means of leads 136 and 137, respectively. Contacts 71 and 72 of tube 60 are connected to terminals 124 and 125, respectively, by means of leads 138 and 139. The terminal 123 is connected by a strap wire 140 to terminal 127. Gontacts 52 and of tube 48 are connected to terminals 126 and 127, respectively, by means of conductors 141and 142. The other contact 53 of this'tube is connected to terminal 128 by means of a conductor 143.

The spark plug used in conjunction with the control of the oil burner is also shown diagrammatically in Figure 2 and is designated generally by the reference character 145. Theplug is connected by leads 146 and 147 to the secondary winding 148 of a transformer 150. The primary winding 149 of this transformer is connected by leads 151 and 152 to terminals 125 and 126, respectively. The conductor 151 is connected to the terminal 125 through the conductor 137, as shown in Figure 2.

The operation of my novel oil burner control is, briefly, as follows:

The first thing to be done is to make sure that the tube 90 is properly set. This is done by operating the reset lever 100 (Figure 6) which causes the tube to be tilted until the member 86 strikes the pin 102. This results in the contacts 94 and 95 being connected through the body of mercury 89.

Now, normally when the oil burner is in an inoperative osition the thermostat 17 will maintain the s aft 18 in such a position as to hold the tubes 48 and in the positions shown in Figures 8 and 7. Of course, it will be evident that the cooling or contraction of thermostat 17 results in the rotation of shaft 18, thus causing tube 48 to be moved to its normal position shown in Figure 8. Obviously this tube 48 in moving with shaft .18 will, through its arm42, move tube 60 to the position shown in Figure 7. In fact, it is the contracted thermostat itself which maintains the two tubes 48 and 60 in their normal positions prior to the operation of the oil burner. When the tube 48 is in this position the contact element 52 is connected to the contact element 55. Moreover, when the tube 60 is in this position the contact element 71 is connected to the contact element 72 (Figure Upon the source of power being connected to leads 129 and 130, current flows through the resistance coil 110 to heat the same so as to bend it, the motor 13, and the three tubes 90, 60, and 48. It is to be understood that in order for the motor to operate both of the switches housed in tubes 90 and 60 must be in their closed positions. If either of these mercury switches is broken the motor will be rendered inoperative. Obviously, the operation of the motor results in the operation of the compressor unit (not shown) of the oil burner proper. As a result of the operation of the; compressor unit the pressure in the air line connected to the bellows 76 (Figure 7) is increased to a suflicient degree to cause the plunger to be projected in the path of the arm 73, thus holding the tube 60in the position shown in Figure 7. It is to be noted that this plunger is normally actuated before the thermostat has been heated and hence before tube 48 has been moved from its normal position. 5 Therefore, it is apparent that the arm 42 of tube 48 will have prevented tube 60 from gravitating to its lower position.

a Current from the power leads 129 and 130 also flows through the mercury in tube 48 connecting contact elements 52 and 55 and through the transformer-150. This results in a spark being emitted by the spark plug 145, thus igniting the charge being pro] ected into the furnace 12.

If the charge of fuel leaving the nozzle 11 of the oil burner is ignited it will result in the heating of the thermostatic coil 17. This coil upon being heated turns in a direction away from extension 24 (Figures 4 and 5), thus revolving shaft 18 and moving tube 48 to a position wherein the contact elements 52 and 55 are disconnected and the contact elements 53 and 55 are electrically connected. As a result of this movement of the tube 48 the transformer 150 is disconnected from the circuit whereby the spark plug 145' will be deenergized. Also, this movement of the tube results in the current flow through the resistance coil 110 being diminished due to the closing of a shunt circuit. It must be understood that all of the above described action takes place in a relatively short time so that the coil 110 is not heated to a sufficient degree to displace the thermostatic strip 107 laterall l n the event that the thermostatic coil 17 is not heated to a suflicient degree to actuate the shaft 18 before the resistance coil 110 is heated, this coil will operate to move the strip 107 (Figures 2 and 6) upwardly whereby the block 86 and the tube 90 are moved to the position shown in Figure 6. As a resultof this movement of tube 90 the mercury switch therein is opened, thus disconnecting contacts 94 and 95- and breaking the motor circuit whereby the motor will be'rendered inoperative. This is advantageous for the reason that it prevents fuel or oil from being discharged into the furnace when the burner has not been ignited, thus greatly reducing the possibility of a fire or explosion. Obviously, if the motor is rendered inoperative the pressure in the'air system will drop and as a result the sylphon 76 will contract, thus withdrawing the plunger 74 out of the path of the arm 73.

If during the operation of the oil burner the thermostatic strip 17 should be suddenly cooled to a suflicient degree to return the tube 48 to the position shown in Figure 8 the current will again flow in the resistance coil 110. When the current has heated the coil to a given degree it will move the tube 90 to the position shown in Figure 6, as previously de- 05 scribed, thus rendering the motor inoperative.

Now it will be understood that if the air pressure in the compressor unit system of the burner connected to bellows 76 should at any time fail during the operation of the burner the plunger 74 will be withdrawn out of the path of the arm 73 and the tube 60 will drop to its lower position wherein the contact elements 71 and 72 will be disconnected, thus rendering the motor inoperative. Thereafter the gradual cooling of the furnace thermostat will result in the turning of the shaft 18, thus causing the two tubes 48 and 60 to be moved back to the positions shown in Figures 7 and 8, namely the starting positions of these tubes. During this movement of tube 48 the arm 42 through its screw 43 contacts the arm 83 connecting the tube 60 and returns tube 60 to its normal position, thus placing the motor in a condition to be operated. This screw adjustment allows the con tacts 52 and 55 of tube 48 to be connected slightly ahead of the contacts 71 and 72 of tube 60 so'that the spark will be on when the motor starts. The screw 43 is adjustable to vary the time in which the tube ,60 will be returned to its normal position by the tube 48.

As previously described, the thermostatic strip 111 is responsive to changes in atmospheric temperature and is adapted to compensate for any change in the thermostatic strip 107 due to variation in atmospheric temperature. In other words, the strip 111 is set to flex in an opposite direction from the strip 107 (Figure 6) and inasmuch as these two metallic strips are joined together the strip 111 must of necessity compensate for any variation in the strip 107. The time of operation of the switch operating strip 107 can be varied by moving the thermostatic metal strip 111 forward or back thru the means of the adjusting screw 113. For example, if the switch operating strip 107 is set to function for two minutes in a room where the temperature is 80 F. and the room temperature should be lowered to say 50, it will mercury switch in tube 90 in two minutes.

Now I desire it understood that although I have illustrated and described in detail the preferred form of my invention, the invention is not to be thus limited, but only in so far as defined by the scope and spirit of the appended claim. 4

-I claim as my invention:

In combination, an oil'burner, a 'motor for operating the same having a power circuit, an electrically operated time limit cut-ofi' in said power circuit to deenergize the motor on ignition or combustion failure, an electric igniter; a thermostat positioned to be heated by the burner, a switch device operable there'- by electrically connected to said igniter and said time limit cut off to operatively deenergize the same when said thermostat is heated, an eocentrically pivoted switch in said power 'be found that this strip will still operate the circuit mechanically connected to said first switch to be held in closed position thereby when said thermostat is cold and to be released for opening movement when said ther- 5 mostat it hot, and a device operable by the pressure of air fed to the burner during burner operation to maintain said pivoted switch in closed position.

In testimonyv whereof I have hereunto sub- 10 scribed my name at Chicago, Cook county,

CHARLES L. RAYFIELD.

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