US2398099A - Heating system and control means therefor - Google Patents

Description

April 9; 1946. w. s. LANDON HEATING SYSTEM AND CONTROL MEANS THEREFOR Original Filed Sept. 15, 1941 3 Sheets-Sheet l INVENTOR BY WA- M 1) ATTORNE April 9, 1946. w. s. LANDON HEATING SYSTEM AND CONTROL MEANS THEREFOR Original Filed Sept. 15, 1941 3 Sheets-Sheet 2 I INVENT OR Wavy/J MW BY Mk Y Azlm'oansv April 9, 1946. w. s. LANDON 2,398,099

HEATING SYSTEM AND CONTROL MEANS THEREFOR Original Filed Sept. 15, 1941 3 Sheets-Sheet 3 INVENTOR BY W K 3, ea

ATTORNEY Patented Apr. 9, 1946 HEATING SYSTEM AND CONTROL MEANS THEREFOR Walter S. Landon, Detroit, Mich., assignor to Detroit Lubricator Com corporation of Michigan pany, Detroit, Mich, 8.

Application September 15, 1941, Serial No. 410,842, which is a division of application Serial No. 218,720, July 11, 1938. Divided and this application October 28, 1943, Serial No'. 508,001

3 Claims.

My invention relates generally to heating apparatus including a liquid fuel burner, and more particularly to means for controlling the operation of the burner.

One of the objects of my invention is to provide an improved, electrically operated valve for controlling the flow of liquid fuel to a liquid fuel burner.

Another object is to provide a self-contained control apparatus for supplying liquid fuel to an oil burner to maintain a substantially constant temperature in a hot water tank.

The invention consists in the improved construction and combination of parts, to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a part of this specification, I have fully and clearly illustrated my invention, in which drawlugs- Figure l is a view showing diagrammatically my'control apparatus installed in a hot water heating system;

Fig. 2 is a view showing a schematic diagram of the electrical circuit embodied in my invention, and its interrelation with an on burner for heating water;

Fig. 3 is a top plan view of my apparatus with the top cover removed;

Fig. 4 is a view along the line looking in the direction of the arrows but with the top cover in place;

,Fig. 5 is a view along the line 8-5 of Fig. 3,-

looking in the direction of the the top cover in place; V

Fig. 6 is a view along the line 66 of Fig. 5, showing only the electrical control apparatus and its supporting block;

Fig, 7 is a view along the line l'! of Fig. 3, looking in the direction of the arrows;

Fig. 8 is an enlarged plan l -view of the switch means as seen in Fig. 4;

Fig. 9 is an enlarged detail view in section of a thrust spring and its cooperating parts, and

- FigflO is a side view of the bowed thrust spring in an inert position apart from the rest of the apparatus.

Referring to the drawings b characters of ref-\ erence the numeral I represents a chambered casing having an open top wall! over which a cover member 3 is secured, as by means of screws 4. The cover member 3 has a tubular, upwardlyextending portion 5 which forms a chamber-t arrows but with having side walls 1, 8 and endwalls 9, I 0. The

4-4 of Fig. 3,

bottom wall of the chamber 6 is formed by a plate I! held, as with screws l3, to the member 3. The upper wall of the chamber 6 is formed by part of a cover member If: secured by screws [5 threaded into a pair of bosses l5 projecting inwardly into chamber ii from the walls I, 8. The cover member l5 has a. downwardly extending portion 16 which forms the side walls of a second chamber ll located on top of the cover member 3' of the casing I. The chamber IT has a portion of the cover member 3 for its bottom wall and a portion of the cover member l5 for its top wall.

The end wall '9 of the chamber 6 forms an end wall of the adjacent chamber I! and separates chamber I i from the chamber 6. The opposite end wall of the. chamber ll is formed by an upwardly extending portion l'l of an L-shaped angle piece i'l secured by one of each of the screws ,6 and i3 to the cover member 3, The portion H has a pair of apertures, therethrough each of which receives a "BX terminal fitting Ila The portion ll at the top thereof carries a threaded lip i F which receives a screw I'll for securing the cover member I5 thereto. Secured to the bottom wall of easing l is a strainer chamher it having an inlet means l8 connected by means of a conduit member 20 to a suitable source of liquid fuel supply (not shown). The chamber 18 has an outlet 2| leading to a constant level chamber 22 within the casing l, and the flow of fluid through the outlet 2! into chamber 22 is controlled by means of a float valve 23 which maintains a predetermined constant liquid level within chamber 22, alongthe line L-L.

A U-shaped electric magnetic means 24 is located within chamber 6 and comprises a laminated core 25 having one leg 26 secured by means of screws 21 to the plate l2. The other leg 28 of the core 25 is spaced above leg 26 and carries an electrical coil 29 which surrounds and is conthe coil 29 to pivot so that the other end of the armature 35 will be urged into engagement with the open end of the leg 28 to close the magnetic circuit between the open ends of the legs 26, 28. The armature 35 has a portion 36 which extends upwardly toward the top wall portion of the cover member If A bell crank lever 31 is pivoted at the intersection 38 of its horizontal arm 39 and its vertical arm 40 by a pin 4! which is received within an aperture through and secured to the lever 31, as by peening 42. The pin 4! is loumaled in a boss 43 projecting inwardly into the chamber 8 from the side wall 1, intermediate the end wall Ill and armature 35. The leg or arm 39 of the bell crank lever 31 has its end portion rounded, as at 44, and received between shoulders 45, 4B of a valve member 41. The valve member 4'! is located intermediate the boss 43 and end wall 9 and extends vertically downward through an aperture in the plate l2 into the chamber 22. The lower end of the valve member 41 cooper ates with an outlet means 48 of the chamber 22 to control flow oi! fluid from the chamber 22 by reason of its vertical spacing relative to the outlet means #8. The outlet means 48 is connected by a conduit means #9 to a liquid fuel burner 50, as shown in Fig. l. The upper end of the valve member 41 is guided for reciprocal movement within an aperture in an internal boss 52 projecting inwardly into chamber ii from the side wall I. are adjustably held in the boss 52 and cooperate with the valve member 8! to limit upward and downward movement respectively thereof relative to the outlet means 48 and thereby limit the maximum and minimum flow respectively of fluid from the chamber 22.

Projecting from the wall 8 and extending inwardly therefrom into chamber 5 is a boss 55 having rigidly secured thereto, as by screws Elb an upwardly extending carrying member 55 which extends substantially parallel to the arm All of the bell crank lever 3?. A horizontally extending lever member 5'l has one end 58 fulcrumed within an aperture in the carrying member 56 and has the other end 259 loosely received within an aperture in the arm All. The lever member 51 has an aperture midway between its ends 58, 59 which receives one end lid of a rod member 6 I. The other end 32 of the rod member Si is received within an aperture in the upwardly.

extending portion 36 of the armature 35. Clips 63 which are secured in spaced positions by a convenient method on the rod member 66, such as being in grooves. limit separating movement between the lever member 5"! and extended portion 36, which are urged in a separating direc tion by a helical coil, thrust spring 54 surrounding and longitudinal of the member 62 and having its opposite ends abutting the member 5? and portion 36. The spring 64 transmits the thrust of the armature extended portion 36 to A pair of stop members 53, 5d

6! and inert, it is bowed or curved longitudinally, preferably having its longitudinal axis in the form of an arc. The lateral deflection or howing of the spring is sufficient so that when placed on or sleeved over the rod 6i, as in Fig. 9, the spring is tensioned laterally of the rod axis engaging the rod on one side at spaced points and engaging the rod on the other side at an inter mediate point. The spring is therefore held in frictional engagement with the rod and opposes movement of the rod through its core so that when placed in position on the rod member 6 i the spring acts as an anti-rattling means. The rod member Bl, when the valve is in open position, would, if not for the spring 54, merely lie loosely in the aperture through the member 51 and portion 36 and any vibration which might be caused by the magnetic means 24 would rattle the rod member ii to cause an objectional noise. The spring due to its tendency to assume the shape of an arc, irictionally engages the rod member 5i and asthe spring 54 itself is held between the member 5'! and portion 3%, effectively holds the rod memher in! against vibration. Another feature oi this construction is the increased tendency of the spring 64 to prevent vibration, because of the increase in the frictional force due to the compression of spring M, at the time that the tendency of the rod member iii to vibrate is greatest, or when the magnetic means 24 is urging the valve M in a valve opening direction. The end 58 of the lever member 51 is held in fined position by the carrying member 56, and the end 59 moves the bell cranlr lever ill with a force equal to onehalf that exerted by the magnetic means 2 1 but through a distance equal to twice that of the movement of the point of intersection of the rod member ti and the lever member A thermostatic electric switch means 55 is located within climber I! and is carried by a channel supporting member lit between its outwardly projecting, horizontally spaced side portions 57, 68. A vertical connecting portion 59 has extending flange portions 70, 'H which extend outwardly from vertical edges thereof and are secured by means of screws 12 through the wall ii, and the supporting member 68 is held by the screws 72 in fixed relation to the wall 5. The switch means comprises a temperature sensitive power element 13, a switch arm H movable between contact members l5, l5 and H to be hereinafter described more fully, and a stop the lever member 5'! and exerts suflicient opposing or separating force between the lever memher-51 and portion 38 so that upon movement of the armature 35 by the coil 29, toward the lever member 57, the bell crank lever 3'! will be pivoted upon its pin 4i and the valve member 4'?! will be moved into engagement with its stop member 53. The force opposing movement of the bell crank lever 37, upon engagement of valve member 11 with its stop member 53, is now greater than the force exerted by the spring M, and further movement of thearmature 35 into abutting relation with leg 28 is accomplished by compressing the spring 84 which provides lostmotion between the magnetic means 24 and the valve 41 so that the armature 35 will abut the magnet leg 28. The spring 64 is given a permanent set, see Fig. 10, so that when off the rod means 18 limiting movement of the switch arm M. The stop means 18 comprises a Ushaped carrying member 79 having its parallel arms 80, ill of unequal length and having one arm extending on either side of the switch arm '14. The longer arm 8! of the member 19 is spaced vertically above the shorter arm 80 and switch arm M and is secured at the open extended end of arm ill to the lower end 82 of a pin member 33. The pin member 83 extends upward through an aperture 85 extending from a slot or recess 85 in the bottom wall 86 of the supporting block 34 carried by the supporting member 66, and extends above the top wall 8'! of the block 34 through an aperture in the cover member 15 to terminate, as at 88, exterior to the apparatus. The pin member 83 has an annular projecting shoulder 89 spaced from the lower end 82 and located within the aperture 84. The aperture 84 is of a substantially larger diameter than the pin member shoulder 89. The lower end portion reception of an externally threaded cylindrical member 93 having a top end wall 34 with a central aperture therethrough. The internal diameter of the member 93 is of suflicient magnitude to receive the shoulder 09 of the pin member 83, and the upper portion of the pin member'83 is guided by the aperture through thewall 94. The lower end portion 35 of the member 03 projects within the cylinder member SI so that the extreme lower end forms an adjustable abutment 96 for a disc abutment member 91 held from lateral movement by the internal wall of the member 9!. The disk member 91 receives the pin member 83 through a central aperture therethrough so that the member 97 is located concentric with and intermediate the shoulder 89 and end 82 of the pin member 83. A.- helical coil spring 98 is concentric with the pin member 83 and'is held under compression between the portion 80 and the disk member 91,

urging the disk member against the abutment.

90. A second' helical coil spring 80 is located concentric with the pin member 03 and has one end abutting the upper face of the shoulder 89 and the other end abutting the underside of the end wall tit'of the member 93. The spring 99 preferably exerts a force which is substantially equal to one-half that exerted by the spring 08 urging the disk member 91 against the abutment 96. Normally the pin member 83 is urged to the position shown in Fig. 4, but may be either raised or lowered with equal ease by raising or lowering the extending portion 08 which moves the arms 80, BI relative to the switch arm I4. Upon release of the portion 88, the member 83 assumes its normal position, as shown in Fig. 4. By screwing the cap member 93 in the cylinder member BI, I can space the abutment relative to the portion 90 and thereby change the normal position or" the stop means, 18 and the open position of the switch arm I4. After adjustment, the cap member 93 is locked in posi tion by a loclrnut I00 which is threaded to cap member 03 and tightened against the upwardly projecting end wall of the cylinder member 9I to substantially prevent movement of the cap member 93 relative to the cylinder, member M.

The switch means 65, which can be seen in Figs. 5, 6 and 8, has the switch arm I4 and contact members 15, I6 and 11 carried within the slot or recess of the block 35. The arm,

I4 is a channel-like member having a flat base portion IM and downwardly extendin side portions I02. The base portion IOI has a longitudinally extending slot or aperture I03 therethrough and has at one end portion a downwardly projecting lip I04. The lip I04 has a threaded aperture therethrough in which an adjustment screw I05 is threaded so that a conical end portion I05 thereof is extending beneath the base portion IIlI toward the other end I01 of the switch arm I4. The end I01 is pivotally supported by a fulcrum rod member I08 which extends through anaperture in each of the side portions I02. The ends of the rod member I08 are supported on either side of the portions I02 in downwardly extending lugs I03 of a platelilre member IIO secured, as by screws III, to the bottom of the recess of the block 34. The plate-like member H0 is thereby insulated from the casing I. The lugs I 03 also serveto prevent lateral movement of the switch arm I4.

Intermediate the side portions I02 and below the base portion MI is a pivoted toggle lever member I I2 which has one end portion pivoted on the. fulcrum pin or rod member I 08 and the other end portion extending toward the lip I04 and being conical in shape, as at H3. The conical portion II3 extends toward the lip I04 in substantial alignment with the aperture I035. The apex of the conical portion I I3 is spaced from the apex of the conical end portion I06 of the screw I05, and a resiliently urged, collapsible-expansible toggle member I I 4 having oppositely extending, conical recessed end portions is under compression therebetween. One recess of the toggle member I I4 is received by the conical end portion I I3 and the other recess is received by the conical end portion I06. The toggle member I I4 is urged' in an expansible direction by a spring II5 which urges the conical portions I I3, I06 in a separating direction, and the pivoted toggle member H2 in a. rotary movement. The spring IIS exerts its force at such an angle on or relative to the member H2 that upon clockwise movement (see Fig.

5) of the member II2 the component of force opposing movement will decrease upon such clockwise movement even though the spring I I5 which acts according to Hook's law actually exerts a reater total force. It will be evident from the foregoing that the force of spring H5 opposing movement of the member H2 varies as the product of total force of the spring II 5 and the sine of the angle between the line of the spring H5 and a line connecting the portion I 06 with the fulcrum pin E00 oi the lever I I2. For small acute angles it will be noted that the sine will decrease with greater rapidity than the increasing of force of the spring I I5 upon compression. I have found that a spring having a rate of increase of force of 5 pounds per inch. and acting through a maxi mum angle of 3 degrees will work in this apparatus to give a satisfactory decrease in movement of force. The rotary movement of the toggle member I I2 is limited to the foregoing acute angle by a pair of adjustment screws H6, H1 threaded in apertures through the member I I2 so that upon initial movement of the member II2 the member I I2 will move throughout its range of movement due to the breakdown of the opposing force of spring H5. The screws H6, II! also locate the end points of travel of the conical end portion H3 in respect to the bottom of the recess 85 by their engagement with the plate-like member I III. The adjustment screw I05 acts to determine the magnitude of force exerted by the spring I I5 and thereby to determine the differential of operation of the power element I3.

The temperature sensitive power element I3 comprises a cap member I I9 having its open end portion I 20 secured by means of screws III to the lower face of the horizontally spaced side portion 68 of the channel member 06. A bellows member I22 located within the cap member H3 has one end secured in fluid-tight relation to the end portion I20 of the cap member and has the other end of the bellows member sealed to a reentrant movable end wall I23 located within the cap member I I9 to form an expansible-collapsible chamber I24. A temperature sensitive bulb I25 is connected by means of a suitable flexible, small bore tubing 121 to the interior of the chamber I24 and a closed system 8 is formed thereby. The system I28 is evacuated and charged with a predetermined quantity of temperature sensitive, volatile fluid so that with increasing temperature of the bulb I25 the pressure within chamber I2! will increase and urge the movable end wall 523 outwardly toward the open end l20 of the cap member H9 with increasing force.

An internally threaded, cylindrical member I29 having an end wall Hill is secured in fluid-tight relationship within a concentric aperture through the reentrant portion'of the movable end wall 323. The end wall I30 is within the chamber 124 and has a central aperture therethrough in which is sealed one end of a short piece of tubing l3l which is suitably closed at its other end, externally oi the member 129, subsequent to the tubing 1M being used for charging the system H8 with the volatile fluid. The member 523 has a shoulder l 32 within the chamber H4 which forms an abutment and guide for one end of a helical coil spring i33 held under compression between the portion 132 and the inner end wall of cap member H9. The spring Hill is operable in conjunction with the fluid pressure in chamber 124 to urge the wall !23 in an outward direction or toward the lever H2. The spring 3353 is preferably one having a rate of force increase of 28 pounds per inch of length decrease. A screw-threaded, hollow thrust member 534 extends outwardly and is threaded into the cylindrical member 129 surrounding the tubing 13!, and carries at its upward end a member 135 of electric insulating material. The member illcarries a conical member 535 the apex of which is received in a conical recess in the lower wall of the pivoted member H2. length of the upwardly extending thrust member V34 may be adjusted relative to the member H29 by screwing so that the upwardly extending conical end portion ltfi is in proper space relation with the pivoted member H2.

Rotational movement of the pivoted member I ill by the upward movement of the thrust mem her 534 is opposed by a downwardly extending thrust member l3? of electric insulating mate rial which has a conical end portion 138 received within a conical recess we in the upper wall of the member H2. The member H2 is electrically insulated by the member W5 and thrust member I31, and the molded block M, from the casing l to electrically isolate the switch arm 14. The thrust member i3! is urged toward the member H2 by a helical coil range spring MU held under compression against the thrust member E37 by an adjustable abutment member Ml screw-threaded, as at H2, in a nut member 3 secured within an aperture in the side portion 67 of the channel member 56 so that the member MI is operable to be moved relative to the thrust member lil'l to change the acting force of the spring MB. A suitable knob means M4 carried by and removable with the cover member 55 has operative connection with member Hi through a radially extendin pin i455 extending from the member Hi into a slot N5 of the means 4. An upwardly extending stop pin MS cooperates with the pin M5 to limit rotation of the member Hi to less than 380. The downward force exerted by the spring 140, which acts in opposition to the upward force exerted through the cylindrical member 128, may be adjusted externally of the apparatus by the knob means I to change the temperature at which bulb 125 will rotate the pivoted member H2. A spring with an increase in force of 41 pounds per inch decrease in length is satisfactory. Theparticularcharacteristics of the springs H5. H3 and H0 depend upon the magnitude of the acute angle formed between the member H2 and a line joining the conical portion I06 to the fulcrum pin N18. The member H2 in this instance is arranged so that the spring H5 engages the member 122 one inch from the fulcrum pin Hi8 and the springs H3 and M0 and power element 13 engage the member H2 one-eighth inch from the fulcrum pin H331 The springs are so arranged that the moment of force exerted by the spring l W decreases more rapidly than the algebraic sum of the moments of force caused by the decrease of force of spring i133 and increase of force of spring Mil, the resilience of the bellows 122 being taken into consideration as part of the spring H3.

The contact members l5, it are positioned above the arms N and are carried by one end of current conducting spring members Nil, 8 respectively. The spring members Ml, MB are secured adjacent to but in spaced relation with the bottom of the recess 85 at the end opposite to the contact members lb. 15 to binding post members N9, 32 which are preferably molded into the block 34. The contact member ll carried below the switch arm M by a U-shaped current conductingsupporting member ilil having apair of parallel arms ibt, ibi One parallel arm i5? is attached to the post member M8 and the other parallel arm i522, to which the contact member ll is secured, extends below the switch arm 'l'il. The switch arm M is connected by a lead wire i523 to a binding post member lbt molded in the block 3%. An electric conducting strip H513 also molded within the block lid connects a binding post mem bar 158 to the binding post member to which the lead wire M is fastened.

When the switch arm M is in the position shown in Fig. 5, the switch arm will be in e1ngagement with contact members lb, "it. The conical portion 5 it is held from further counter clockwise rotational movement by adjustment screw ill, and the force of the spring H15 of the collapsibleeiipansible toggle member Ht, acting between the portion Hi6 and member i it, will flex the spring members Ml, MB until the contact carrying ends thereof are in engagement with the bottom Wall of the recess 8%. This fieirion of the spring members d ll, Mil will occur after contact has, been made by the switch arm M and will cause a wiping action between the contact members l5, l5 and the adjacent surface of arm M and insure a good electrical contact therebetween. As the pivoted toggle member l H is rotated in a clockwise direction by the power element '13, the conical end portion H3 thereof will pass the line of centers between the conical portion W8 carried by the switch arm M and the fulcrum rod member i lit, and the arm "M will move in a counterclockwise direction with increasing velocity due to the expansive force of the toggle member TM. The spring members 'Ml, M8 will follow the movementof the switch arm M due to the resilient force urging the contacts to their spaced position from the bottom wall and will keep the contact members l5, it in electrical contact with the switch arm it until the arm has gained speed enough to make a quick break with the contacts.

The arm M is stopped in its opening movemerit and is prevented from engaging the contact member H by the engagement of the arm 14 with the underlying arm 88 of the stop means 18. The switch then normally remains in open circuit position until closed by the spring I48 acting in opposition to the power element 13. Should it be desired to close the circuit through contact member 11, it is necessary to push downward the portion 88 01 the pin member 83. The arm 88 against which the arm 14 is urged by toggle member H4 is thereby lowered and the arm 14 is permitted to move into engagement with the contact member 11 under the expansive tone of the toggle member I I4. Upon release of the portion 88, the spring 88 will move the stop arm 88 to its normal position above that of contact member 11 to open the circuitbetween contact arm 14 and the member 11. Should it be desired that the circuit between arm 14 and contact members 15, 18 be closed and the switch arm 14 is in open circuit position, due to the power element 13, the portion 83 may be raised manually so that the arm 88 will lift the arm 14 against the force of the toggle member H4 into contact making position. Release of the pin member portion 88 will cause the arm 88 to be moved to its normal position by the spring 88, and the toggle member I will then be eflectlve to urge the arm 14 to open circuit position.

Now let us assume that the switch arm 14 is in the position shown in Fig. 5, that is, with the temperature sensitive bulb I25 at a lower temperature than the predetermined temperature for which the switch is set to open the circuit between switch arm 14 and contacts 15, 18. The switch arm 14 can now be moved manually from contact members 15,18 to open the circuits therebetween by depressing the portion 88. The arm 8| will engage the switch arm 14 and move it against the force of the toggle member I I4, Further movement of the portion 88 downward will move the switch arm 14 into circuit making relation with the contact member 11. Release of the portion 88. will allow spring 88 to move the stop arms 88, 8| to normal position and the expansible toggle member II4 will move the arm 14 to contlaictnmaking position. with contact members The application 01' the apparatus described may be seen from the diagrammatic view of a water heating system shown in Fig. l. The numeral 288 represents generally my apparatus hereinbeiore described, supplied with electrical energy through lead wires 28I, 282 connected to a suitable source of supply. An electric air supplying means 283 is supplied with electrical energy by lead lines 284, 285 connected to the switch means 85 of the apparatus 288. The output of air from the means 283 is directed through a conduit means 288 to the liquid fuel burner 58, supplied with a suitable liquid fuel by the conduit means 48 from the apparatus 288. The heat output of the burner 58 is'directed toward a suitable hot water tank 281 connected into a suitable hot water system (not shown). The temperature sensitive bulb I25 is located within a suitable bulb well 288 in heat exchange relation from the electrical supply is connected to the terminal post I55. The lead wire 285 is connected to the post I58 and to the electric air supplying means 283, and the other lead wire 284 connected to the supplying means 283 is connected at its opposite end to the terminal post I54 which is electrically connected to the switch arm 14. The terminal post 33 is connected to one lead wire 3| of the magnetic coil 28 and the other lead wire 38 of the coil 28 is connected to the terminal post 32 and. therethrough to the directly connected contact member 18. In connecting my equipment in this mannerto the switch means, I substantially prevent the undesirable circumstance of having the oil valve 41 held open by the magnetic means 24 and the air supply means 283 deenergized. Each means 24, 283 is supplied directly by the lead wire 282. The lead wire 284 connects the means 283 directly to the switch arm 14. The lead wire MI is directly connected to the contact members 15, 11 and the means 24 is directly connected by lead wire 3| to the contact member 16. If the switch arm 14 is in any contact making relation with member 15 or 11, the circuit through the means 283 must necessarily be closed. The switch arm 14 must necessarily be in circuit making relation to the lead-wire 28I to be able to complete the electrical circuit through the magnetic means 24, even though contact member 15 should possibly through any chance be in circuit making relation with the switch arm 14. It has been shown that any time the arm 14 is in circuit making relation with wire 28I, the means 283 is electrically connected to the supply, and as the arm 14 must be in contact with member 15 or 11 to energize the magnetic means 24, there is therefore no chance of having the valve member 41 open without the air supply means 283 being energized, even though the contacts should arc and stick together.

In operation my device works as follows: Assuming the water in tank 281 to be at a lower temperature than the minimum predetermined temperature for which the apparatus 288 is set to operate, the fluid pressure in the sealed system I28 will be relatively low and the switch means will be in the position shown in Fig. 5. The magnetic coil 28 will be energized and holding the armature 35 against the leg 28. The valve member 41 will be against its stop member 53 in maximum open position and the oil will flow through the conduit 48 from the chamber 22 and into the burner 58. The switch means 85 will also be making circuit through the electric'air supplying means 283 and the air requisite to insure proper operation of the burner 58 will be supplied. The heat output from the burner 58 is absorbed by the water in tank 281 thereby raising its temperature. When the predetermined maximum temperature for which the thermostatic switch means 65 is set to operate is reached, the pressure within the system I28 will have increased sufficiently to force the movable wall I23 outward from the cap member H8 in opposition to the opposing force of the spring I48. The pivoted toggle member I I2 will upon initial inovement' by the power element 13 move throughout its range of movement without any additional increase in the force exerted by the element 13 due to the breakdown of forces opposing movement of the member I12. It will be noted that while the total force exerted by the spring H8 increases upon movement oi the member H2 in tact members 15. 11. The other lead wire 282 7 a clockwise direction (see Fig. 5) the component of force of the spring H-actuaily decreases due to the angle at which it acts on the member H2 and the moment of force exerted on the member H2 decreases. The decrease of moment of force must be greater than the algebraic sum of the pin or rod member I08 momentof force of spring H5 exerted in opposition to movement of the member H2 is zero and upon a slight further movement of the member H2 in'the clockwise direction the moment of force exerted by the spring H5 in fact acts to aid the power element in its movement of the member H2. The additional aiding moment of force exerted by the spring I I5 increases upon continued movement of the member I I2 due to the angle of operation of spring H5 with respect to member H2 and is true even though the total force exerted by the spring H5 decreases upon spring expansion. As the portion H3, portion I05 and centerline of the spring H5 pass overcenter the spring which, of course exerts a reactionary force in the opposite direction-pf an equal magnitude to that exerted in the first direction acts to move the switch arm 14 in a counterclockwise direction (see Fig. 5) with an increasing force and consequently increasing arm velocity. due to the change in angle at which the force of the spring H5 acts on the switch arm 14. Not only does the present construction allow for a quick break due to the increase in the force exerted by the spring I I5 on the arm 14 but also the spring members I41, I48 act to move the contact members 15, 16 respectively, against the arm 14 until the arm 14 is travelling at a high rate of speed thereby preventing excessive arcing when the contact members part due to a prolonged positioning of the contact members 15, 16 in arcing relation with the arm 14.

. As was stated hereinbefore the thermo sensitive bulb I25, responsive to the temperature of the controlled medium, is connected for purposes of convenience by a small bore or capillary tube -I21 to the power element 13. As the'power element 13 moves the member H2, the volume of the chamber I24 increases and if the pressure therein is to remain constant or in balance with the pressure of the volatile fluid within the bulb I additional fluid must be supplied thereto from the bulb I25 and this additional fluid must v pass through the capillary tube I21. Movement of a quantity of fluid through a small bore or capillary tube requires an elapse of time and therefore the bellows member I22 cannot immecliately with a rapid movement move from its switch closed position to its switch open position but must move with a relatively slower movement depending upon the rate of breakdown of the opposing forces and the rapidity with which the fluid will flow from the bulb I25 through the capillary tube I21 to chamber 124} in an efiort to maintain the predetermined high pressure in the chamber I24 corresponding to the predetermined high pressure in bulb I25 "caused by the predetermined maximum temperature for which the switch means is set to operate.

The power element 13 and member H2 it is seen operates with a snap action insofar as the forces having once started movement, the members will not again come into equilibrium until they have moved into their final position but the ing which is flexible and easily handled. The pivoted toggle member clockwise with a slow snap action and the switch I I2 therefore rotates arm 14 opens the circuits to the magnetic coil 29 through the contact member I8 and to the'air supplying means 203 through contact 15 with a fast snap action. The armature will rotate counterclockwise, as seen in Fig. 4, allowing the bell crank lever 31 to rotate clockwise and the valve member 41 to move vertically downward to engage its minimum stop 54. The valve member 41 when against its stop member 54 is preferably set to deliver a minimum flow of fuel to the burner 50 so that proper combustion therein with air being supplied by natural convection will occur and the burner 50 will stay ignited. The heat output under this condition is preferably sufhcient to maintain the'water at. the given predetermined temperature; but sufilciently low so that there is no danger of the water becoming too hot.

As there becomes a demand 'in the closed system I28, until the force exerted by spring I40 overcomes the opening force of the end wall member I23. The pivoted toggle member H2 will then rotate counterclockwise causing the switch arm 14 to rotate with a snap action clockwise into circuit making position with the contact members 15, 16 to energize the air supplying means 203, which will then supply the requiredextra air to the burner 50. The coil 28 also being energized, the armature 35 will be drawn toward the leg 28 and the valve member 41 will be lifted by the bell crank lever 31 against its upper stop member 53 to increase the flow of fuel to the burner 50. The valve member 41 preferably engages its stop member 53 before the armature 35 engagesthe leg 28 and thereby is prevented from further movement in an open direction. The bell crank lever member 31 is prevented from further counterclockwise rotation and the spring 64 compresses under the closing force of the magnetic means 24 and operates as a lost-motion means to allow the armature 35 to engage the magnet leg 28. Engagement of the armature 35 and leg 28 is necessary to prevent driection closer or further away from the line of center of the conical portions I06, H3 and fulcrum rod member I08 so that the movement of force exerted by the expansible contractible toggle member I I4 is lessened or increased to demand a corresponding change in pressure with the systern I28 to exert the necessary force on the thrust for hot water from the system, the burner under minimum fuel 'aso'aooe What is claimed and desired to be secured by I Letters Patent of the United States is:

1. In a heating apparatus, a iiuid fuel burner, electrically operated means for supplying'air to said burner, electrically operated means for supplying fuel to said burner, switch means having a pair of fixed contact members and a movable switch arm operable on movement in one direction to make circuit simultaneously with said members, said contact members being electrically connected respectively to a source of current supply and to said electrically operated fuel supplying means, said arm being electrically connected to said air supplying'means so that said air supplying means will be energized whenever said fuel supplying means is energized, a contact member engageable by said switch arm upon movement of said switch arm in the opposite direction and electrically connected to the source of current supply, means to stop movement of said plying fuel to said burner, mam means mm a apalrofiixedcontactmembenandamovable switch arm operable on movement in one direction to make circuit simultaneously with said members, said contact members being electrically connected respectively to a source of current supply and to said electrically operated fuel supplying meanssaid armbeing electrically connected to said air supplying means so that said air supplying means will be energized whenever said fuel supplying means is energized, a contact member engageabie by said switch arm upon movement in the opposite direction and electrically connected to the source of current su ply. and manually operable means controlling the engagement oi said switch arm with said last-named contact member.

3. In a heating apparatus, a fluid fuel burner, electrically operated means ior supplying air to said burner, electrically operated means for supplying fuel to said burner, switch means havins a pair of fixed contact members and a movable switch arm operable to make circuit simultaneously with said members, thermostatic means operable to move said switch arm into engagement with said fixed contacts, said switch am having a lost-motion connection to said thermostatic means tor movement of said switch arm irrespective of said thermostatic means, manually operable means cooperable with said connection to move said switch arm relative to said thermostatic means, said contact members being electrically connected respectively to a source or current supply and to said electricallyoperated fuel supplying means, said arm being electrically connected to said air supplying means so that said air supplying means will be energised whenever said fuel supplyin means is energized, and a contact member connected to the source or current supply and engaged by said arm upon operation oi said arm by said manually operable means. WALTER B. LANDON.

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