US2585278A

US2585278A - Fuel burner controller

Info

Publication number: US2585278A
Application number: US55962A
Authority: US
Inventors: Paul F Shivers
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1948-10-22
Filing date: 1948-10-22
Publication date: 1952-02-12
Anticipated expiration: 1969-02-12

Description

Feb. 12, 1952 p, SHIVERS 2,585,278

FUEL BURNER CONTROLLER Filed Oct. 22, 1948 4 Sheets-Sheet 1 Inventor PHI/L E 5/ V535 (Ittorneg Feb. 12, 1952 P. F. SHIVERS FUEL BURNER CONTROLLER 4 Sheets-Sheet 2 Filed Oct. 22, 1948 3nnentor P/JUL E 5/f/V5/75 Gttomeg Feb. 12, 1952 P. F. SHIVERS FUEL BURNER CONTROLLER 4 Sheets-Sheet 5 Filed Oct. 22, 1948 25b, 28c, 28d

attorney Feb. 12, 1952 p, SHIVERS 2,585,278

FUEL BURNER CONTROLLER Filed Oct. 22, 1948 4 Sheets-Sheet 4 3nnentor P/IUL F l/IVfFS Gttorneg Patented Feb. 12, 1952 FUEL BURNER CONTROLLER Paul F. Shivers, Minn eapolis, Minm, assignor to Minneapolis-Honeywell Regulator Company.

Minneapolis, Minn.,

a corporation of Delaware Application October 22, 1948, Serial No. 55,962 13 Claims. (Cl. 175-375) This invention relates to improvements in fuel burner controllers of the type which provides for the initiation of the supply of fuel to a furnace and the substantially simultaneous ignition thereof, upon a demand for heat output by the furnace. A furnace controller of this type is illus trated and described in the Sparrow et al. patent. No. 2,420,105, dated May 6, 1947. This invention differs from the device shown in the above mentioned patent in that it provides for shutting off the igniting means upon proper or satisfactory ignition of the fuel. In addition to this, the present invention provides a single manual controller which will simultaneously reset a safety switch and place various elements of the device in proper relationship for a desired timed sequence of operation, after there has been a safety shutdown of the furnace by the control device, or after a long summer shutdown of the furnace, during which time the elements may have gotten out of step for one reason or another.

In controllers or devices of this type, it is common practice to provide a slip-friction mechanism responsive to stack temperatures to establish a holding circuit for the relay in the event ignition takes place and to provide a safety shutoff switch, in series with the fuel controller, which will out off the fuel supply in the event that ignition does not take place. The well known function performed by the slip-friction mechanism of control devices has its drawbacks in that once in a great while the clutch of the slip-friction means fails to grip its actuator as soon as it should and, therefore, gets out of step, requiring the manual resetting thereof to put it back in step." While the average householder may not appreciate the necessity for placing the controller in step, they usually know or have been told about the means'for resetting the controller after a safety shutdown, which probably occurs more often than the device gets out of step. It is with this problem of providing simpler means for a householder to put all of the elements of the controller and the furnace back into proper operation, should the ignition means fail to cutoff, or the slip-friction means get out of step, or there is safety shutdown, that this invention is primarily concerned.

One of the objects of this invention is to provide a fuel burner controller having a single man ually actuatable member that will actuate an igniter switch to its open position, reset a safety switch and place a slip friction mechanism in "step" upcn a single actuation of the member.

Another object of the invention is to provide a control device for a fuel burning furnace that has 8. simple and inexpensive mechanism for cutting off the igniter after ignition has taken place and may be manually actuated to shut off the igniter in the event that automatic means for shutting it off fails to operate.

A further object of the invention is to provide in a furnace controller a simple but reliable means for resetting a safety switch and for placing a slip-friction mechanism in step.

Still another object of the invention is to supply an ignition switch that has means to cause a quick breaking of its ignition contacts.

Other objects and advantages of the invention will become apparent upon reading the following detailed description thereof in conjunction with the appended drawings in which:

Figure l is a side elevational view of the controller with portions thereof broken away;

Figure 2 is a bottom view of the controller with portions thereof broken away;

Figure 3 is a schemmatic showing of elements of the controller and the control system of which they form a part;

Figure 4 is an elevational switch units of the controller;

Figure 5 is a plan view of the relay of the controller with portions thereof broken away;

Figure 6 is a side elevational view of the relay with portions thereof broken away;

Figure 7 is a side elevational view of the safety switch and the manual controller or reset means: and

Figure 8 is a plan view of the safety switch and manual controller or reset means.

In the drawings, wherein like reference numerals indicate the same parts, the reference numera1 ll designates the panel upon which the various mechanisms of the controller or control device are mounted and secured. Mounted on the panel II by bolts or other suitable fastening means are a conventional step-down transformer [2, a safety cutout switch 13, a relay [4, and a switching mechanism housing l5. Positioned on the opposite side of the panel from the switching mechanism housing is a tubular member I6 carrying a mounting flange I! which is slidably adjustable over the intermediate portion thereof. The flange has spaced openings l8 to provide for the bolting of the controller to a stack (not shown) of a furnace (not shown). The tube It is secured to the panel II by bent over ears l8 extending through a backing plate I la and/or openings in the panel. The backing plate Ila is secured to the panel ll either by welding or by any other suitable means. Terminal blocks l9 and 20 are suitably secured to view of one of two inwardly bent ears on the side walls of the panel ii to facilitate connection of the controller to other elements of the control system.

As can best be seen in Figures and 6 of the drawing, the relay i4 comprises a relay coil 21 mounted on a core member 22 of general U- shape. An armature member 23, having a bearing plate 24 secured thereto by means of bolts 25, is pivotally mounted on a pronged pivot 26 suitably secured to one leg of the relay core 22. A tension spring 21 extends between the outer end of the bearing plate 24 and the outer end of a laterally projecting arm 26a of the pivot 23, to normally urge the armature away from the magnet. A plurality of parallel

flexible contact arms

28, 28a, 28b, 28c and 23d (see Figures 3 and 6) are clamped to the armature 23 between two insulation members 29 and 30 (see Figures 3 and 6).

Arms

28b, 28c and 28d are electrically connected. These flexible contact arms are adapted to engage fixed contact arms 3|, 3Ia, Mb. 3 lo and 3id (see Figure 3) clamped between an insulation block 32 and a latch unit 33 by means of a bolt 34 screw-threaded into the other leg of the U-shaped core member of the relay as shown in Figure 6.

The latch unit 33 is formed of two longitudinally grooved

blocks

35 and 36 of insulation material which, when clamped together, provide an open-ended guide-

way

31 and 31a. The block 35 has a transverse opening 33 near one end thereof and a notch 39 at the adjacent end, for reasons to be described hereinafter. The block 36 has transverse openings 40, 4i and 42 for purposes to be described below. An arm 36a extends laterally from the main portion of the block 36 to provide a protective cover and stop for the flexible contact arms. The longitudinal groove 31a in the block 36 is laterally widened to provide shoulders 43 (see Figure 5) to provide abutment shoulders for a latch member 44 now to be described. Said latch member having a general A-shape with outwardly extending feet 45 which are adapted to move into and out of engagement with the shoulders 43, is slidably mounted in the

longitudinal grooves

31 and 31a under the bias of a spring 45. The spring, due to its position in the recesses of the block 36 (see Figure 6), normally biases the latch member 44 toward the block 35 and the feet 45 toward the shoulders 43. An opening 46 in the latch member is notched out at 41 the width of the adjacent main portion of the armature 23 while the main opening 45 is slightly Wider than a head 23a on the outer end of the armature 23 forming a shoulder that is to be engaged by said head in the normal inoperative position of the relay. The latch membe 44 fits sufficiently lOOSe in the longitudinal groove 31a that it may be deflected laterally or longitudinally of the armature so as to move out of alignment with the head 23a, thus enabling the narrow portion of the armature to slide down into recess 41 of the latch member for reasons to be described hereinafter. A cross piece 43 of insulation material spans another recess 43 communicating with the opening 48 and is positioned to normally engage an extension on the flexible contact arm 28a when the relay is in its deenergized condition. The outer end of the latch member 44 is bent laterally to form a cam surface 440 to cooperate with another cam element of the control device to effect the lateral shifting of the latch member out of alignment with the head 23a. It will thus be seen tthat energization of the relay will cause movement of the armature about the pivot member 25 in a direction to bring the flexible contact arms into engagement with the fixed contact arms and to move the latch member 44, through head 23a, to its innermost position. The elements of the relay will stay in this position until said cam element deflects the cam surface 44a and consequently the latch member 44 out of alignment with the head 23a, thus permitting the spring 46 to slide the latch member 44 longitudinally in the groove 31a. This will cause the bridging member 43 to snap the flexible contact arm 23a out of engagement with fixed contact Ma and to bring feet into engagement with the shoulders 43. thus limiting the outward movement of the latch member.

Referring now to Figures 1, 2 and 3 of the drawings, the switching mechanism in the housing I5 is positioned directly above the relay and comprises elements which perform the same functions as the switching mechanism disclosed in the above mentioned Sparrow et al. patent. A lazy W-shaped temperature sensing element 50 of well known construction is secured at one of its ends to the inner end of the tube i6 by means of a bolt while the other end thereof is secured by a bolt to a connecting rod 5| which in turn is connected through a spring type of universal joint 52 (see Figure 3) to a control rod 53. With the exception of a cam deflector member 54 extending downwardly below an adjustable plate 55 (Figure l) and adjustably secured to a switch actuating clutch plate 80 (Figure 3) through a mounting,bracket 56 (Figure l), the details of the switching mechanism form no portion of this invention. However, to enable one skilled in the art to practice this invention, the mechanism will be more or less schematically described with reference to Figure 3 of the drawing. A wall 51 of the switching mechanism housing supports two cold contacts 58 and 59 which are of equal length and a third cold" contact 60 which is slightly shorter than the contacts 58 and 59. On the other side' of the wall 51 are two hot" contacts BI and 62 which are of equal length. Two

other walls 63 and 64 of the mechanism housing are spaced on opposite sides of the wall 51 and slidably carry bearing stems 65 and 66, respectively, of bridging

switch units

81 and 68 having body portions made of insulation material. The unit 63 has a laterally extending cylindrical portion 69 telescopically receiving a laterally extending stem 10 from the switch unit 51. A spring 1| surrounds the members 69 and 10 and extends through a large opening 51a in the wall 51 to normally urge the two switch units apart. Each of the switch units carries a serpentine-shaped flexible contact arm member 12 and 12a (see Figure 4) which is secured to the body portion by means of rivets 13 leaving three

flexible contact arms

14, 15 and 15 and 14a, 15a and 18a. respectively. A clutch plate 11 is slidably mounted on the con trol rod 53 and bears at its outer end against the end of stem 56, to urge the switching unit 68 toward the left when the control rod 53 moves toward the left, upon heat developing in the stack of the furnace. The unit can continue moving toward the left even after

contacts

14 and 16 engage fixed contacts 52 and SI respectively, due to the flexing of the

contacts

14 and 16, until the clutch plate 11 engages an adjustable stop 13. Thereafter, the control rod 53 will slip through the clutch plate 11 in a well known manner. The spring 1| causes the clutch plate 11 to follow 76 the movement of the control rod 53 toward the right when the stack temperature cools down. It will move toward the right until the clutch plate l1 engages an adjustable or fixed wall 19, whereupon the rod 53 will slip through plate ll. A clutch plate 88, which carries a cam-shaped abutment 54 for cooperation with the cam 44a on the relay latch member 44, operates in the reverse direction with respect to the cam plate 11. In other words, it is moved toward the right by the same movement of the rod 53 and is urged toward the left by the spring II as the rod 53 moves toward the left. It is limited in its leftward movement by an adjustable stop 8| and in its movement toward the right by adjustable stop 82. With the main exception that the switching mechanism is shown below the control rod 53,

the relay side of said control rod, whereas in fact it is on the other side of said control rod (see Figure 1), the elements of the switching mechanism are shown in the positions they would assume when the relay is deenergized and the stack of the furnace has cooled down to its low or no fire temperature.

Referring now to Figures 7 and 8, the means for manually actuating the control rod 53 outwardly so as to bring cam 54 into engagement with cam 44, for the purpose described above and for moving the control rod 53 sufliciently far through the clutch plate 88 so as to assure the closing of the cold contacts 14a, 15a and 15a on contacts 58, 68 and 59 respectively, comprises a pivoted lever 83 secured by a pivot 94 to a frame 85 of the safety cutout switch I3. A cam portion 83a of the pivoted lever is engaged by a stud 86 extending laterally from a manually operable lever 81 pivoted to the frame 85 at 88. An insulation disk 89 is mounted on the outer end of one leg of an L-shaped pivoted lever 98 and engages the free end of a flexible contact arm 9| biased toward said disk. A second insulation disk 92 is mounted on the pivoted lever 81 in transverse alignment with but spaced from a second flexible contact arm 93 normally biased against the contact arm Hi. The end of the other leg of the L-shaped lever 98 is positioned to bear against the free end of a bimetallic arm 94 of a heat motor to be presently described. The arms 98a and 94 are so positioned that a predetermined heating of the bimetallic arm 94 will cause movement thereof out from under the arm 98a, permitting said arm 98a to drop or move inwardly thereof under the bias of the resilient or flexible contact arm 9|. The contact arm 93 will tend to follow the contact arm 9| but comes into engagement with the insulation disk 92 to limit the following movement, thus breaking the contacts between the arms 9I and 93. A conventional resistance heater 95 is positioned between and riveted to an end of the bimetal 94 and an end of a cooperating bimetal 94a, each of which moves the outer end of the bimetal 94 outwardly from under the free end of arm 98a upon a rise in temperature thereof. The other end of the bimetal arm 94a is riveted through a spacer 96 to a third bimetallic arm 91 which serves as an ambient temperature compensating unit in that it carries the bimetallic arms 94a and 94 in the opposite direction inwardly of the arm 98a upon a rise in temperature, in a manner well known in the art. The other end of the bimetallic arm 91 is riveted to a pivoted lever 98. A spring 99 positioned between ears 98a and 856 on the lever 98 and frame 85, respectively, and a bolt I88 passing through said ears and said spring, provides means for adjusting the angular relationship of the lever 98 and thus the calibration of the heat motor element, to determine the temperature at which bimetal 94 moves out from under the arm a. This determines how long it will take for the contacts 9| and 93 to separate after the heat motor has become energized for a reason to be described presently. The lever 99 is held in its pivoted position by means of a clip spring I riveted to the frame 85. The ends I82 and I83 of the heater resistor are connected to conductor bars I84 and I85, respectively. These conductor bars, as well as the fixed ends of the contact arms 9| and 93, are bent in two planes and extend through the base 85a of the frame 85, with terminal ends 9Ia, 93a, I84a and I85 extending outwardly beyond said base. The contact arms and bars are clamped to said base 850 between insulation blocks I88 and I8! by means of a bolt I88 and nut I89. They are so positioned with respect to each other that they are electrically separated.

The control rod 53 passes through the outer free end of the lever 93 and carries at its outer end a bearing plate 530 held thereon by a split washer 53b resting in an angular groove in the rod 53. It is thus seen that if the switch were in its open condition and the manually actuatable arm 81 were rotated clockwise about its pivot, the insulation disk 92 would first move contact arm 93 further out of engagement with 9I before 2, lug 81a on lever 91 could engage 98a, to rotate insulation disk 89 clockwise to cause movement of the contact arm 9| and the end of arm 98a to the position shown in Figure 8 of the drawing. As the lever 81 moves clockwise, the cam 85 will ride outwardly on cam 83a to cause the lever 93 to move counterclockwise into engagement with abutment 53a and to move the control rod 53 toward the left. The control rod 53 is moved sufliciently far to the left to assure the closing of contacts 58-'I4a, 98-4511 and 59--|5a upon releasing the lever 81. An abutment 95b limits the outward movement of the lever 83 so as to prevent damaging of the member 58.

The above described controller is adapted to be used with a conventional room thermostat II8 (Figure 3) having two blades III and H2 adapted to cooperate with contacts II3 and H4, respectively. The contact II3 is connected through line 5 to one side of the secondary coil of transformer I2. The contact H4 is connected through line I I8 to relay contact 3Ic. The contact arms III and H2 are connected through line II! to contact 3Id of the relay. Relay contact arm 28 is connected through the terminal panel 28 to the motor of a fuel feeding means or draft regulator or any other means which regulates the supply of combustion material to the furnace (not shown). The other side of the motor H8 is connected to. one high voltage line II9. One side of a conventional ignition means I28 is connected through line I2I and line II8b to line I I9. The other side of the ignition means is connected through line I22 to contact member 3Ia on the relay. The contact 3i of the relay is connected through line I23 to the other line I24 of the high voltage line to complete circuits through the motor and ignition means when the relay is energized closing contacts 28--3I and contacts 28a3la. The ends of the primary coil of the transformer I2 are connected through lines I25 and I26 to the high voltage lines H9 and I24, respectively. It is to be understood that all of the lines to the room thermostat. the

motor, the ignition means and the high voltage line are made through the terminal panels I9 and 28 in a conventional manner.

The internal wiring of the controller may best be understood by describing it in conjunction with an explanation of the operation of the controller in the system illustrated in Figure 3 and as installed on a furnace. With the controller in proper position on a furnace, with the temperature sensing element 58 within the stack of said furnace, and there being no fire present in the furnace, as well as a satisfied room condition, the elements of the system will be in the positions shown in Figure 3 of the drawing Operation Upon a demand for heat due to the lowering of the room temperature surrounding the thermostat H8, the blade III of the room thermostat will come into engagement with fixed contact H3. This will not have any effect on the system or controller as the contacts 28d and 3Id are separated. However, as the room cools down still more, contact arm H2 will engage contact H4 and complete a circuit to the relay I4 from the upper side of the transformer secondary through line H5, contact H3, arm III, arm H2, contact H4, line H6, line I21, contact 88, contact 15a, contact 14a, contact 58, line I28, heater 95, line I85, contact arm 9|, contact arm 93, line I29, relay I4 and line I38 to the lower terminal of the transformer secondary coil. Energization of the relay causes movement of

contact arms

28, 28a, 28b, 28c, 28d, and the armature 23 and latch 44 to their right hand positions completing the circuits to the fuel feeding motor and the igniter as described above and other circuits to be described presently. After the fuel has ignited and the stack has risen in temperature sufficiently to cause the temperature sensing element 58 to move the control rod 53 toward the left, the clutch plate I1, due to its angular relationship with respect to the rod 53, will grip said rod and move along with it so as to move the contacts I4 and 16 toward the left. Switch unit 81 will move along with the control rod 53 due to the compression of spring 1I between the bodies of the switch units 61 and 88. The switch units are factory calibrated so as to cause contact 15a to separate from cold or recycling contact 68 before

contacts

14 and 16 engage or bridge their cooperating hot" contacts 52 and 6 I, respectively.

It will be readily apparent that the calibration could permit the contacts 15a and 88 to separate after the hot" contacts close, but this would shorten the scavenging or purging period to be described presently. Due to the greater amount of flexing of contact arms 14 and IS with respect to contact arm I and the gap between contacts SI and 16 and 62 and 14, the contacts 14a and 18a will not break from their cooperating cold" contacts 58 and 59, respectively, until after the hot contacts have closed. While one of two temporary holding circuits completed around contacts H2 and H4 upon energization of the re lay, the one completed through contacts 28d3Id and 28c3Ic will be broken when contacts 68 and a separate with the first increment of movement of the control rodv the second temporary holding circuit through contacts 28d3Id and contacts 28b3Ib, line I29 and contacts 59 and 16a will be maintained. The heating of heat motor 85 will continue until the hot contacts close shunting out the heater and establtshing a third main holding circuit around the contacts H2 and H4 through switches 28d-4ld. 28b3lb, line I29, line I38, contacts 82-14 and contacts 6I15 and line III to contact arm H. The shunting out of heater prevents sufficient heating thereof to cause tripping of the safety cutout switch 8I-93, which would obviously take place should there be flame failure prior to the closing of the hot" contacts. The contacts 14a and 18a may be calibrated to separate from contacts 58 and 59 respectively after a small increment of movement of the control rod 53 after the hot" contacts have closed, it being only important that there be some overlapping of the time that the hot" and cold" contacts are closed during the movement of the control rod 58 toward the left. The breaking of these cold contacts breaks the circuit to the heater 95 to permit it to cool off during the operation of the burner. Operation of the cam 54 with respect to cam 44 so as to trip the latch and cause said latch to open the ignition switch 28a--3Ia is not critical but preferably timed to terminate ignition shortly after contacts 14a--58 and 1811-49 have separated, to insure steady initial burning of the fuel during the starting cycle.

Should there be a flame failure after combustion has been established, and while the space or room thermostat H8 is still calling for heat, the temperature sensing unit 58 will start to cool and move the control rod 53 toward the right. As an explosion might result if ignition took place at this time, of the unburned fuel remaining in a gaseous state in the furnace, the controller is calibrated so as to have the switching unit 51 move sufficiently far before it engages adjustable stop 8| as to assure breaking of the hot contacts before the cold contacts make and to allow time for the unburned fuel to pass out of the furnace. The breaking of the hot" contacts immediately deenergizes the relay I4 and shuts off the supply of fuel to the furnace. Obviously, the length of time that it takes for the cold" contacts to close following terminal of combustion, may be regulated by varying the distance of adjustable stop H with respect to fixed contacts 58 and 59 and 88. Even after contacts 14a and 16a engage contacts 58 and 59, respectively, the controller will not recycle due to the fact that shorter contact 68 controls the starting of the control system, the contact 28b being separate from contact 3Ib upon deenergization of the relay. This provides an additional purging time for the unburned gases in the furnace and assures safe operation thereof. The length of the purging time may obviously be varied by adjusting the position of stop 8|.

Should there be ignition failure prior to the closing of the hot" contacts, the continued heating of heater 95 will cause the tripping of the safety cutout switch I3. Should there be failure of operation due to the fact that the cold" contacts fail to make in one of their operating cycles, either one or both of the control units will be put back into operating condition by the simple manipulation of the single manual control 81 in the manner described above. Movement of the lever 81 clockwise pulls the control rod 53 slightly beyond the outermost position which the rod would reach in the normal operation of the controller and will simultaneously move the contact arms SI and 93 and arm 98a to positions which enable the bimetal 94 to align with arm 98a and to hold all three arms in their operating positions upon releasing the lever 81. Also. unless th "e is something materially wrong with the clutch 88, the

releasing of the lever 81 will permit the rod 53 to move the cold contacts to their closed position.

Except when the safety cutout switch is open, operation of the fuel feeding means is controlled by the room thermostat. That is, the fuel feeding means can start operating only when the room thermostat calls for heat and will stop operating when the room thermostat becomes satisfled. Should it be desirable for any reason to terminate ignition from adjacent the furnace immediately after the relay has become energized, as when the apparatus is being tested and adjusted, it is obvious that operation of the manually operable lever 81 will move the control rod 53 to trip the ignition switch latch.

As it is apparent that the above described controller may have wider use than that disclosed above, and that modifications may be made therein without departing from the spirit of the invention, it is to be understood that the scope of the invention is to be determined solely by the appended claims.

I claim as my invention:

1. A circuit controlling device comprising a relay, a first relay operated switch, a second relay actuated switch, a. latch biased to move and to hold said second switch in its open position and having an abutment thereon, an arm on said relay normally in alignment with said abutment for moving said latch away from said second switch upon actuation of said relay in a switch closing direction, a deflector means positioned to contact and disengage said arm from said abutment to permit said latch to open said second switch from its closed position, condition responsive slip friction means for actuating said deflector, a normally closed third switch in series with said relay for deenergizing said relay upon a predetermined condition arising, a stop positioned to limit the movement of said deflector means in its arm actuating direction and a manually operable member for simultaneously resetting said third switch and actuating said slip friction means in a direction to press said deflector means against said stop.

2. A circuit controlling device comprising a re lay, a first relay operated switch, a second relay actuated switch, a latch biased to move and to hold said second switch in its open position, means operable by said relay for moving said latch away from said second switch upon actuation of said relay in a switch closing direction to enable said second switch to close, a deflector for disengaging said latch from said means to permit said latch to open said second switch from its closed position, condition responsive slip friction means connected to said means and a manually operable member for actuating said slip friction means in a direction to disengage said means from said latch.

3. A fuel burner controller comprising a switch, a relay, slip-friction means for actuating said switch, a plurality of relay actuated switches, latch means for one of said relay actuated switches positioned to cause closing thereof upon energization of said relay, a relay operated arm positioned to actuate said latch means, a cam on said slip-friction means for engaging and releasing said latch means to cause opening of said one switch at a predetermined condition of said slip-friction means, a normally closed safety switch connected in series with said relay for breaking the circuit thereto upon an unsafe condition arising, and means for simultaneously re- 10 setting said safety switch and actuating said slipfriction means.

4. A fuel burner controller comprising a plurality of switches, condition responsive slip-friction means for actuating said switches, a relay, a plurality of relay actuated switches, latch means for one of said relay actuated switches biased toward switch open position but movable by said relay to cause closing thereof upon energization of said relay, and a cam on said slipfriction means for engaging and releasing said latch means from said relay to cause opening of said one switch at a predetermined position of said slip-friction means.

5. A fuel burner controller comprising a switch, a relay, condition responsive slip-friction means for actuating said switch, a plurality of relay actuated switches, relay actuated latch means for one of said relay actuated switches positioned to permit closing thereof upon energization of said relay, said latch means being biased toward switch open position, a cam on said slip-friction means for engaging and releasing said latch means from said relay to cause opening of said one switch at a predetermined position of said slip-friction means, a normally closed safety switch connected in series with said relay for breaking the circuit thereto upon an unsafe condition arising, and means for simultaneously resetting said safety switch and actuating said slipfriction means.

6. A fuel burner controller comprising a switch, a relay, condition responsive means for actuating said switch, a plurality of relay actuated switches, resiliently biased relay operable switch engaging latch means for one only of said relay actuated switches positioned to move away from said one switch to permit'closing thereof upon energization of said relay, and a cam on said condition responsive means for engaging and releasing said latch means from said relay to cause opening of said one switch at a predetermined position of said condition responsive means.

7. In an ignition and fuel control device, the combination comprising an electromagnet, an armature positioned to be moved by said electromagnet, an abutment shoulder on said armature, fixed contact points, resilient contact blades movable with said armature to engage said fixed contacts upon energization of said electromagnet, a latch normally in engagement with said shoulder and biased toward engagement with only one of said contact blades and toward its normal positon, and condition responsive means having means for moving said latch out of its normal position in engagement with said shoulder to permit said latch to move said one contact blade away from its cooperating fixed contact.

8. In an ignition and fuel control device, the combination comprising an electromagnet. an armature positioned to be moved by said electromagnet, an abutment shoulder on said armature, fixed contact points, resilient contact blades movable with said armature to engage said fixed contacts, a slidable latch normally in engagement with said shoulder and spring biased toward and against only one of said contact blades, and condition responsive means having means for moving said latch out of engagement with said shoulder to permit said latch to move said one contact blade away from its cooperating fixed contact upon a predetermined condition arising.

9. In an ignition and fuel control device, the combination comprising an electromagnet, an armature positioned to be moved by said electromagnet, an abutment shoulder on said armature. iixed contact points, resilient contact blades movable with said armature to engage said i'lxed contacts when said electromagnet is energized, a longitudinally slidable and laterally movable latch normally in engagement with said shoulder and spring biased toward one of said contact blades and into alignment with said shoulder, and condition responsive means having means for moving said latch laterally out of engagement with said shoulder to permit said latch to move said one contact blade away from its cooperating fixed contact upon a predetermined condition arising.

10. In a furnace control, the combination comprising a relay actuated means carrying switches, one of said switches controlling energization of fuel feeding means and a second of said switches controlling ignition means, a latch member normally latched on said relay actuated means, said latch member having an abutment thereon for engagement with the ignition controlling switch and being movable with said switches in a switch closing direction and being unlatchable from said relay actuated means for movement to a switch opening position, and condition responsive means for moving said latch member out of actuating engagement with said relay actuated means.

11. A control device comprising a control switch operable by a slip-friction mechanism, a safety switch operable to its open position upon the occurrence of a predetermined condition, and means operably connected to both of said switches for substantially simultaneous actuation thereof by a single movement of said means.

12. A control device comprising a condition responsive slip-friction mechanism operably connected to a control switch, a relay actuated switch, a condition responsive switch in series with the relay of said relay actuated switch, means operable by said slip-friction mechanism to open said relay actuated switch, and means associated with said slip-friction mechanism and said condition responsive switch for causing substantially simultaneous actuation thereoi.

13. In a control device having a relay, a safety switch controlling said relay and a switch operated by a slip-friction mechanism for controlling said safety switch, the improvement comprising a manually operable lever pivoted adjacent said safety switch for resetting said safety switch, a cam on said lever, a second lever having a cam surface and pivoted so as to be actuated by said cam moving over said cam surface during the safety switch resetting movement of said manually operable lever, and means on said second lever for operably engaging said slip-friction mechanism.

PAUL F. SHIVERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,560,932 Eaton Nov. 10, 1925 1,782,937 Perry Nov. 25, 1930 1,877,275 Cunningham Sept. 13, 1932 2,005,584 Heyroth June 18, 1935 2,251,703 Frank et al Aug. 5, 1941 FOREIGN PATENTS Number Country Date 202,321 Great Britain June 12, 1924 680,982 Germany Sept. 11, 1939