US3080143A - Control device - Google Patents

Description

, March 1963 w. A. BIERMANN ETAL 3,080,143

CONTROL DEVICE 4 Sheets-Sheet 1 Filed July 30. 1959 34 Fm. l

2 INVENTORS WlLuAM A.B\ERMAN|-| ROBERT P\'.BAUER B LQURDELS V. MCARTY ATTORNEY March 5, 1963 w. A. BIERMANN ETAL 3,080,143

CONTROL DEVICE Filed July 30, 1959 4 Sheets-Sheet 2 4-2. l 40 Fla. 3

4-4 I, l l v ll "1 I I Ill I so INVENTORS WHJJAM A. BIERMANN Roses-r R. BAUER LOURDES V. MCARTY Fla. 6 ATTQFRHEY March 1963 w. A. BIERMANN ETAL 3,

CONTROL DEVICE Filed July 30. 1,959 4 Sheets-Sheet 3 i Fla. 7

20 14- z II 30 2 Fleas \HVENTORS W\LLIAM A. BIERMANN ROBERT R.8AUER LOURDES V. MCARTY BY 2 4 y E ATTQRNEY March 5, 1 3 w. A. BIERMANN ETAL 3,080,143

CONTROL DEVICE 7 Filed July 30, 1959 1 4 Sheets-Sheet 4 7b 35 b2 I W 4 75b4- d e 50 7o r a 44 f I I g I 7 33 3o 34 2b a: ANT\C\PATED LINE, SWWCH THERMOSTAT UPPER HOT ROD H Fl uwzaeg PH INVENTORS i W\LL\AM A. BIERMANN 1 ROBERT R.6AUER HI Louaoes V. MCARTY ATTORNEY United States Patent Ofitice insane Patented Mar. 5, T953 CGNTRGL DEVICE William A. Biermann, lirooinield, Robert R. Earner, New

Berlin, and Lourdes V. McCarty, Milwaukee, Wis, assignors to Controls Company of America, Schiller larlr, Ilh, a corporation of Delaware Fiied .luly 3t 1959, Ser. No. $30,572 6 Claims. (til. 251--11) This invention relates to a fuel flow control device, and particularly to a control for regulating oil flow to vaporizing burners.

The principal objection to pot type burners is the soot accumulation resulting from the poor combustion characteristics of the fuel under different operating conditions within the burner. During the ofi cycle, the burner is generally operated with micro-pilot flow or no flow which requires electrical ignition. In either case, the heat generated in the pot is insutlicient to vaporize a large quantity of oil. Hence, when the thermostat calls for heat, poor combustion will result if the fuel flow is established rapidly. Thus the incoming oil is not adequately vaporized and the tiarne becomes smoky. If, on the other hand, the control provides a low fuel flow rate (as distinct from the very low or micro condition), the burner can adequately vaporize the incoming oil to assure a clean flame which will in turn heat the pot sufficiently to vaporize a higher flow rate if and when provided. With the pot preheated, the flow rate can be increased graduaily until full iiow has been reached without going through a smoky condition.

The primary object of this invention is to provide a iuei flow control which will regulate the flow to the burner in accordance with the above outlined desirable conditions.

- A further object of this invention is to provide a control which substantially reduces the number of times this critical range of operation must be passed through.

The above objects are accomplished with the control which will be described in detail hereinafter. This control is compatible with use in conjunction with either no iiow or micro-pilot fiow during the oii cycle. When the thermostat calls for heat, the flow rate will be increased to a low iire condition and held at that rate. The oil flowing into the pot will be adequately vaporized at this flow rate and will, in turn, generate enough heat in the pot to handle increased flow which the control will provide after the flow rate has been maintained at low flow long enough to heat the pot. The flow rate thereupon increases gradually to full how and will remain at full flow under control of the room thermostat. When the thermostat is satisfied, the flow rate will be gradually decreased to the low flow rate condition. The present control will, however, maintain this low flow rate condition for some period of time during which the room thermostat may call for heat. if the thermostat does not call for heat, the control will ultimately reduce the flow rate rapidly to micro-pilot or ofi. Under normal heat loads, the thermostat will call for heat again and the smoky stage is completely avoided since the low flow rate keeps the burner hot.

Other objects and advantages will be pointed out in, or be apparent from the specifications and claims as will obvious modifications of the single embodiment shown in the drawings in which:

FIGURE 1 is a plan view of the present invention with the cover removed.

FIGURE 2 is a side view partly broken away showing the present invention.

FIGURE 3 is an end view of the present invention.

FIGURE 4 is another end view of the present invention.

FiGURE 5 is taken along 5-5 of FIGURE 2 showing the bimetal heater.

FIGURE 6 is a detail of the low flow regulator.

FIGURE 7 shows the present invention with a limit control energized.

FEGURE 8 shows the parts in the positions assumed at low flow.

FIGURE 9 shows the parts at high fire.

FIGURE 10 shows the control shortly after the thermostat opens.

FIGURE ll shows the wiring diagram for the control.

FIGURE 2 shows a constant level oil control device of the type having a flow control inlet valve 1%) to maintain a constant level of fuel in casing 11. The constant level control includes an outlet valve assembly 12 having a standpipe 14 provided with port 16 with which metering slot 13 on the lower end of valve stem 29 registers to provide the desired flow rate. open by spring 22 compressed between the upper end of the standpipe and valve shoulder 24. It will be noticed that lever 26 acts against the valve shoulder to over-ride the bias of the spring 22, holding the valve closed. This lever is part of the limit control provided by this assembly and is pivoted on cover plate 28 and biased downwardly by spring 3%. The upstanding end 32 of the lever has a socket in which the right hand end of hot rod 34 is fitted, the other end of which is fixed to the upwardly sheared stationary bracket 33. The hot rod has a resistance heater wound thereon to expand the rod when energized and rock the lever about its pivot to lift the left end of the lever oii the valve shoulder and permit the valve to open, if allowed to do so by the other control apparatus. The hot rod and lever provide a limit control (for stack temperature or other condition) which is constantly energized and the circuit to the resistance heater will be broken upon the stack temperature exceeding a pre-selected temperature for the control. At this point the hot rod will cool and spring 36' will force the lever down to over-ride the bias of spring 22 and close the outlet valve. It will be obvious that the action of the resistance heater circuit could be reversed to provide for heating the hot rod upon the dangerous condition occurring. The illustrated form is preferred since it fails safe in the event of power failure.

The upper end of the valve stem proiects through aperture 37 in the cover and, in the position shown in FIG- UEE 7, bears against the bottom end of pin 35 depending from lever 36. This lever is pivoted on pin id supported in the mounting bracket 42. Spring d4 urges the lever 36 downwardly against the valve stem, while the upstanding right-hand end as of the lever is acted upon by hot rod connected thereto through adjustable socket 5i and having the other end abutting depending flange 52 on the mounting bracket. When this hot nod is energized is will be appreciated that there is considerable mo tion multiplication due to the lever arms involved and this multiplication plus the rapid response or" the hot rod will rapidly lift the lever and hence pin 35 from the upper end of the valve stem. The valve stem will rise due to the bias of spring 22 until it contacts the flow regulator lever 54 as shown in FIGURE 8.

A slow response lever 56 is under the control of heater 53 mounted on heavy metal bar as which acts as a heat sink connected at its right end to the mounting bracket. The heat from the heater must first be transferred to the heat sink and from there to bimetal 62 to warp the bi-' metal arm upwardly. The left hand end of the bimetal is provided with a yoke 64 engaging the end of lever 56. This lever is pivoted on pin so and extends upwardly The valve stem is biased assures over the pivot point to the left and is bent down in back to engage the yoke carried by the bimetal. As the lever 56 moves upwardly about its pivot, it carries U shaped bracket as with it. Bracket 68 is biased by spring 74 so that as the lever 56 moves upwardly, it pivots on the shoulder 72 of the bent back portion of the lever 56 until the T arm 7'5 of the bracket engages the lever. This action may be seen clearly by comparison of FIG- URES s and 9. FIGURE 9 shows the limit er clockwise motion of the U shaped bracket about its pivot. As this bracket rocksabout the shoulder, it eventually relieves the pressure on the fuel regulating lever to permit the lever to rock about its fulcrum under the influence of hair spring 74 and the valve spring 22.

In the position shown in FIGURE 9, it will be noted that the upper left end of the U shaped bracket has moved into the arcuate path of the free end of fast acting lever 36. Upon de-energizing the upper hot rod, the fast acting lever will swing down and would normally shut off fuel flow rapidly but latch '76 provided on the upper end of the U bracket will catch the lever and hold it in the upper position until the lever 56 has been returned to the low flow position by the bimetal and the U bracket starts to pivot until the fast acting lever is released from the latch. The bimetal is relatively slow acting since the heat sink must also cool down producing a slow reduction in fuel flow rate and may actually hold it at low fuelflowrate for'aperiod of time. In the absence of a new thermostatic demand for heat in this period of time, the lever will snap down to either cutoff the flow or reduce itto micro-pilot conditions. This time delay before cu off gives a modulating action. Thus when the flow rate has beenreduced'to low and has remained there for a short period of time and the thermostat calls for heat, the flame can be rapidly increased, compatible with the response characteristics of the bime'tal heat sink, to the high flow condition. Under normal heat loads, the control eliminates going through the troublesome combustion stages mentioned above. However, if it is a mild day, and the thermostat does not call for heat within the period of time provided by the control, the control will then snap the flow rate to off or micro-pilot and thus go through the sooty stage fast enough to avoid any difficulties in combustion.

At the low fuel flow rate, the air for combustion is normally supplied to the burner by natural draft. As the valve is opened to increased the fuel flow, a point Will be:- reached where the natural draft will not be sufficient to nroduce complete combustion within the burner. The control is calibrated so that at a point in the upward movement-of lever 56, fan switch 77' will be actuated by finger 78 pivoted on pin 86 and: biased upward by spring 82. The finger engages a calibration screw 84 in lever 56 so that the point in the fuel flow rate which requires additional air can be adjusted to meet any operating conditions.

FIGURE ll shows the wiring diagram for the above described control. The operation is obvious in view of the above and the legends applied thereto. From the above description and wiring diagram it will be appreciated that other control devices may be utilized to achieve the same result. The most obvious would be to utilize a fast acting bimetal in place of the upper hot rod 48. It should also be appreciated that any fast acting motor device such as a solenoid could be used in lieu of the upper hot rod. Using a solenoid would of course require the addition of a transfer or holding switch that would be regulated by the slow acting bimetal. A slow acting bimetal would regulate the control between low and highwith the solenoid over-riding the bimetal between low and 0E. Other changes should be apparent from the specification and claims.

It will be appreciated that before the control operates, lme-switch 88 and limit switch 90 must be closed to energize the lower hot rod 34 to hold the lever 26 in position where it will not interfere with the movement of the valve stem 2%. When thermostat $2 is satisfied the parts will be in the position shown, either being off or at micro-pilot. Now when the thermostat calls for heat, the fast acting lever 36 controlled by the upper hot rod 48 will rapidly risenout of the way (FIGURE 8) permitting the valve stem to come up to the flow regulator 54 where it is detained until the heat given off by heater 58 mounted on the heat sink 69 can be transferred to the bime tal 62 which will gradually; actuate lever 56 and permit the flow regulator lever 54 to slowly move to the position shown in FIGURE 9 where high fuel flow rate has been reached. Upon satisfaction of the thermostat, the upper hot rod is tie-energized and cools rapidly, allowing the fast acting lever to rest on the catch on bracket 68 so that control of the return motion of the valve stem is retained. by the slow acting. bimetal arm rather than having the fast acting lever snap the valve shut. This permits a gradual decrease in the flow rate to the low flow position and, by proper adjustment of latch 76'carriedby the bracket, a desired time lag can be provided at low fuel flow before the fast acting lever 36-is released to shut off fuel fiow. If a new demand for heat isimade by thethermostat during this time delay, the fuel flow rate will be. gradually increased.

This type of control avoids the objectionable sooty. condition when the thermostat calls for heat and under normal heat demand will not allow the control to go to off or micro-pilot, achieving a degree of heat modulation not normally found in thermostaticallycontrolled devices. When an anticipated thermostat is coupled with this control, the flow control device will not, under normal heat demand, go to the low flow rate, but will come down to some intermediate, level whereupon the anticipated thermostat, which is inherently faster cycling than an unanticipated thermostat, will renew the call for heat and bring the flow back-up. Hence the combination of. an anticipate-d thermostat with this control will tend to modulate the oil flow at a level above the low flow rate which level will be determined by the heat demand for the day. Hence, on a very cold day, the modulation will take place very near the high range of flow while on a milder day the modulation will range over awider variation in flow rate.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may bemade therein without departing from the spirit of the invention or from the scope of the appended claims.

l; A fuel-flow control comprising a valve for regulatopening direction, fast and slow acting valve operating means b'Othfl'BSPUI'lSlVC to a control condition to allow the valve to move in thevalve opening'direotion, the slow acting valve operating means acting on the valve at a low flow position to take control of the valve from the fast acting valve operating means, the slow acting valve operating means thereafter regulating motion of the valve be tween low andhigh fire positions of the valve, and means carried by the slow acting operating means for engaging the fast acting operating meansupon termination of the control condition to prevent operation of the fast acting operating means, said engaging means releasing the fast acting operating means for closure of the valve after the slow acting operating means has closed the valve to a predetermined position.

2; A control accor'ding' to claim 1 in which said engaging means does not release the fast acting operating means until the slow acting operating means has reached said predetermined position and hasbeen maintained in that position for a predetermined period of time.

3. A fuel flow control comprising, a valve for controlling the flow of fuel, said valve being biased in the valve opening direction, first heat motor means positioned to engage the valve and responsive to a control condition to allow the valve to move to an open position, second heat motor means responsive to a control condition holding the valve to a low fuel flow rate position, said holding means gradually allowing the valve to move to a high flow rate position in response to the control condition, means carried by the second heat motor means for preventing the first heat motor means from closing the valve in the absence of the control condition, said second heat motor means gradually returning the valve to the low fuel flow rate position in the absence of the control condition, and said preventing means releasing the first heat motor means to close the valve after the valve has been returned to the low flow rate position.

4. A fuel flow control comprising, a valve movable between minimum and maximum flow positions, bimetal means operative to regulate the movement of the valve between a flow rate intermediate the minimum and maximum flow positions, said bimetal means being responsive to a control condition and acting at a predetermined gradual rate when both increasing and decreasing the flow control, and a hot rod means operative to move the valve rapidly between the minimum flow position of the valve and said intermediate position, and a second fast acting hot rod means positioned to engage the valve and responsive to a second control condition to move the valve to the minimum flow position.

5. A fuel flow control comprising a valve for controlling the flow of fuel, said valve being biased in a valve opening direction, a first electrically energizable valve operator means normally biased to hold the valve closed and adapted to be electrically energized to move to a position clear of the valve allowing the valve to move freely to an open position under the influence of the opening bias, a second electrically energized valve operator means normally operable to limit said free opening movement of the valve under the influence of its opening bias to a low fuel flow rate position, said second valve operator including means to limit the opening movement of the valve between low fuel rate position and maximum flow rate position to a predetermined rate of movement, said second valve operator including time delay means for holding the valve at low fuel position for a predetermined period of time during closing movement of the valve from maximum flow rate position to low flow rate position, said time delay means of the second valve operator engaging and restricting movement of the first valve operator in valve closing direction when the first and second valve operators are de-energized so that the second valve operator thereafter controls and gradually moves the valve to low flow rate position.

6. A control according of claim 5 wherein said time delay means releases the first valve operator to quickly snap the valve to closed position after the valve has been returned to the low flow position for a predetermined time interval.

References Cited in the file of this patent UNITED STATES PATENTS 1,697,432 Martin Jan. 1, 1929 2,116,605 Kelly May 10, 1938 2,118,443 McCorkle May 24, 1938 2,335,212 Landon NOV. 23, 1943 2,355,436 Hay-ter Aug. 8, 1944 2,373,324 Marti-n Apr. 10, 1945 2,461,615 Taylor Feb. 15, 1949 2,582,334 Huntley Jan. 15, 1952 2,608,996 Forman Sept. 2, 1952 2,703,606 Johnson et al. Mar. 8, 1955

Claims (1)

1. A FUEL FLOW CONTROL COMPRISING A VALVE FOR REGULAING FLOW TO A BURNER, SAID VALVE BEING BIASED IN A VALVE OPENING DIRECTION, FAST AND SLOW ACTING VALVE OPERATING MEANS BOTH RESPONSIVE TO A CONTROL CONDITION TO ALLOW THE VALVE TO MOVE IN THE VALVE OPENING DIRECTION, THE SLOW ACTING VALVE OPERATING MEANS ACTING ON THE VALVE AT A LOW FLOW POSITION TO TAKE CONTROL OF THE VALVE FROM THE FAST ACTING VALVE OPERATING MEANS, THE SLOW ACTING VALVE OPERATING MEANS THEREAFTER REGULATING MOTION OF THE VALVE BETWEEN LOW AND HIGH FIRE POSITIONS OF THE VALVE, AND MEANS

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