US2381437A - Control means for draft regulators - Google Patents

Description

Aug. 1, 194.5.

v M. w. CREW ET AL CONTROL MEANS FOR DRAFT REGULATORS Filed May 1, 1942 INVENTOR MORRlS W. CREW S$ORGE A. SHORT ATTORN EYS 2 SheetS- -Sheet 1 v 1945- M. W.-CREW ETAL CONTROL MEANS FOR DRAFT REGULATORS 2 Sheets-Sheet 2 Filed May 1, 1942 Fla-7 T R R s 0M m TRH N mC R wA m N T SE A HG m m GB Patented Aug. 7,' 1945 CONTROL- MEANS FOR DRAFT REGULLATORS Morris W. Crew and GeorgeA. Short, Cleveland, -Ohi0,'assign0rs to The Hotstream' Heater'Com- I 1 ,pany, .ClevelamL'Ohio, a corporationof Ohio Application May 1, 1942, Serial 'No. 441,300 '5Claims. (01. 236-45) This invention relates to improvements in control means for "draft regulators, particularly where they involve means for preventing the flow of cool air through heating equipment during the period when the burner is shut down.

"An object of the present invention is to provide improvements for use with a draft stabilizer damper on the stack side of the furnace. Such a damper normally pivots freely in a, thimble mounted on the furnace pipe or'breeching, balancingthe draft 'by meansof a weight on the Y 'dampe'r'so as to maintain a predetermined fur-- nace draft. An object of thepresent invention is' to provide "means for reducingathe draft through the furnaceto a minimum during inoperative periods of the burner or during those periods when automatic control means is not call ing. for the production ofadditional heat; The present device also provides for maintaining a short interval of normal draft after the burner is' shut down for the purpose ofcarrying off prodducts-of combustion from the last increments of fuelburned-during'the demand period. This is particularly advantageous with oil burning equip-' ment where normal operating draft is necessary for a short interval, generally between'lO to 15 seconds or more after the oil burner is shutoff.

'At the sametime our improved equipment provides for restoring the normal draft immediately upon ademand for additional heat-from the fur-' nace so that combustion is immediately resumed under the most favorable conditions, and puffing and smoky start is eliminated. Another object of the present invention is to provide novel'automatic equipment for produc-. 7 ing the abovenamed result by the use of a motor adapted'to be stalled without injury, thereby providing' equipment of va. very simple form and adapted to be connected in electric circuits using customary or standard voltages without the necessity for special transformers and the like. Other objects and advantages will appear from the accompanying drawings and description and the" essential features will be set forth in the claims.

' In the'drawings, Fig. 1 is a vertical sectional View of the regulator along the line l-*[ of Fig.

C Fig. 2 is a similar view showing anotherposition. of the parts; Fig. 3 is a fragmental'view'taken in a'similar position "to Figs. land 2 and showing still another position of the parts; Fig. 4 is an enlarged fragmental View of certain of the ,parts' of Figs. '1, 2" and 3,- showing other positions thereof; Fig. 5 is a sectional view taken "along the'line' 5f 5 of Fig. 1; Fig. "6 is an enlarged.

fragment'al sectional view taken along the line 6.:6 of Fig. 5; while Fig. 7 isa diagrammatic view illustrating one use of our improved device.

In the'various views a furnace is shown at l0 having a .draft pipe .II connected with a stack 12. :Our invention may be used whether the fuel is solid, liquid or gaseous, but in the present instance We have illustrated an oil burner I 3 having a blower M which is driven through shaft In from motor I6. -A very satisfactory means for c'ontrolling'the draft'for such a'furnace regardless of thetype (if-burner or fuel used in a draft stabilizing damper I1 pivotally mounted by means of a pivot 18 which-works inside pockets 18a of the damper frame. Adjustable weights l9 and 2'6 balance the damper so that the draft act- "ing in the direction ofthe arrow of Fig. '1 and tending toopen the damper is balanced against the weights l9 and 20 so that the desired draft conditions are maintained in the furnace regardless of changing circumstances. Our improved device isarranged to permit this customary action to take place during such periods as the burner l 3 is operating in response to a demand for additionalheat while at the same time providing positive meansfor'opening the damper I! to a position of minimum draft and holding it open during stand-by periods when there is no demand'for additional heatfrom furnace H1. This prevents the "drawing of cold air through the furnace in the case of gas and liquid-fired furnaces and conserves the heat in the furnace setting during such stand-by periods. In the case of coil-fired furnaces it prevents the burning of'the fuel bed faster than necessary during such stand-by periods.

Mounted at some convenient point near the damper l isa housing 2| in which is mounted a motor 22' of a type adapted while energized to be stalled Without injury thereto. A satisfactory Mfg. 00., Inc., and marketed under the name Synchron, but motors satisfactory for the purpose arefproduced by others. The shaft directly driven bythe motor is indicated at 23 in Fig. 6 and acts through aset of reduction gears 24 to drive the final shaft 25 at a very great reduction in speed as compared to the shaft 23, The reduction here may be of the order 'of approximately 1750 .to 1 In other words, if the motor shaft 23 turns. at 1750 R. P. M. then the shaft :25 will turn at about one revolution per-minute.

Fastened to the shaft 25 so as to turn withit is the-bellicranklever 26. One endofthis-lever carries the pin 21. The position of the parts shown in Fig. 1 is what we have called the burner-operating position which permits damper I! to swing freely in response to draft demands. The position of the parts shown in Fig. 2 corresponds to what we have called stand-by position and corresponds to the open position of damper l1 to provide minimum draft, whenever heat is not being demanded of the furnace I0. In the position shown in Fig. 1, the pin 2'1 underlies and engages a hook 28a on the upper end of bar.

28. This bar is mounted for vertically sliding and oscillating movement by means of a pin and slot connection. In the present instance a slot 281) in the bar 28 receives a pin 29 which is threaded into the housing 21. They lower end of bar 28 is connected by link 30 to the damper 11. It will be noted that the link fits loosely in the hole 280 of the bar and passes through an elongated slot 31a of an arm 3| which is rigid with damper H. A wing nut 32 is threaded on the lower end of link 38 to adjust this connection as desired.

The motor 22 when energized moves lever 26 clockwise as viewed in Figs. 1 to 4 until lever 28 engages the stop pin 33. This position is maintained as long as heat is being demanded from the furnace. Upon deenergization of the motor 22 spring 34 moves lever 26 in a counterclockthe depression of hook 2811 as shown in full lines in Fig. 4 and because the upper end of bar 28 is prevented by the keeper nose 350, from the following the pin 21. Thereupon the bar 28 starts to fall downwardly as shown in dot-dash lines in Fig. 4, under the influence of gravity. Thus very shortly after motor 22 is energized the damper "is released for its normal stabilizing action. I

In Fig. 7 we have shown a diagram illustrating one use of our invention but in no sense limiting ourselves to such a use alone. In this view the motor 22 is supplied with current from the lines L1, L2 which may be the usual 115 volt supply found in many installations. The motor 22- is of a type to operate on this voltage. In one of the supply lines is illustrated a thermostat 38 which may be a room thermostat or the like for controlling the demand apparatus when heat is required from furnace I8. Connected in circuit is the motor l6 if such a motor is required either for driving a forced draft fan 14 or for driving a coal stoker or the like. In the case of a gasfired furnace there might be no occasion for wise direction from the position of Fig. 1 to that of Fig. 2, lifting pin 21 and bar 28 and pulling upon link 30 to positively open damper l1 and hold it in the open position. It will be noted upon comparing Figs. 1 and 2 that when spring 34 in Fig. 1 is in its most extended position and therefore providing the greatest pull, it is workingthrough a comparatively short effective lever arm as represented approximately by the horizontal distance between the center line of spring 34 and shaft 25. As the spring approaches the position of Fig. 2 and loses some of its tension, this effective lever arm increases so that theresult is the application of a substantially constant torque on lever 26 by the spring 34.

It will be noted that as pin 21 moves from the position of Fig. 1 to that of Fig. 2 it travels in the arc of a circle and because of its engagement with the hook 28a, the upper end of bar 28 must follow the same arc, the bar meanwhile pivoting about the point 29. Means is provided to prevent the hook 28a on the upper end of bar 28 from following this arcuate path when pin 21 moves in a clockwise direction away from the position of Fig. 2 so as to cause pin 21 to very quickly clear the hook 28a, thus uncoupling the releasable coupling formed by pin 21 and hook 28a and permitting the bar 28 to drop promptly, restoring damper IT to its normal stabilizing action. To this end we provide a latch or keeper 35 pivotally mounted in the housing at the point 36 and overbalanced for freely pivoting action in a clockwise direction until such movement is limited by engagement with the stop 31. A nose 35a, is formed on the keeper so as to engagein frontof the upper end of bar 28 as shown in Fig. 2 when the parts are in the stand-by position.

The position of the parts as they are about to I reach stand-by position is shown in Fig. 3; Here the upper end of bar 28 has engaged and lifted the nose 35a of the keeper and on further slight counterclockwise movement of lever 26 the parts will drop into the position of Fig. 2, at which time pin 29 engages the bottom of slot 281). As the parts move out of this position upon ener gization of motor 22, the releasable coupling is uncoupled, since the pin 21 soon moves out of such a motor but our device would work as illusstrated in Fig. '1' without any motor 16. In the case of a gas-fired furnacean electrical device for turning on the gas might be supplied in place of the motor 15.

Theoperation of our device in a typical installation. would be as follows. When thermostat 38 closed thecircuit of Fig. '7 in response to a demand for heat or more heat, the circuit would be completed through Li, lines 39 and 48, motor 22, and line 4| to L2. Motor 22 would start at the same time that the burner l3 started to operate. Almost immediately the parts would move as described in connection with Fig. 4 so as to uncouple the releasable coupling 21, 28a and release bar 28 which would drop immediately by gravity, causing'link 38 to release damper I! for its normal stabilizing action during the period when the burner was operating. When the parts reach the position of Fig.1, the motor is stalled by the engagement of lever 26 against pin 33. When the demand for heat is reduced and thermostat 38 is thereby satisfied it breaks the circuit to motor .22, whereupon spring 34 starts to move the parts from the position of Fig. l to that of Fig. 2, it being realized that bar 28 is held on pin 29 so that pin 21 automatically engages beneath and is recoupled to the hook 28a in the burneroperating position of the parts. The swinging of lever 26 in a counterclockwise direction from the position of Fig. 1 to that of Fig. 2 is retarded because of the reduction gearing 24. It is impossible for spring 34 to. back-wind the reduction gearing 24 very rapidly, so that the-reduction gearing serves'with the spring 34 as a time delay means, affording a brief period of the order of a quarter to one-half a minute required for the parts to move from the position of Fig. 1 to that of Fig. 2. This provides a short period of normal draft after burner I3 is shut down which is quite essential in the 'case of an oil-fired burner to prevent gassing back. When motor 22 is again energized, bar 28 is released from the positioIT of Fig. 2 and drops immediately to the full extent of slot 282), thus releasing damper ll for the immediate provision of full draft required for furnace operation.

Our device is thus complete in one small unit, as exemplified in housing 21, which-need only be mounted near the furnace and connected to any standard draft stabilizing damper such as V 2,381,437 1 that indicated at n and the wires of a, 115 volt system properly connected to motor 22. We have thus provided avery simple and efficient device adapted to operate over long periods without attention and adapted to provide excellent furnace operating draft conditions for furnaces using many different types of'fuel.

Referring again to Fig. 7, ashunt line 42 may be provided around .the thermostat. Switch 43 in this line would be normally open but might be closed by hand if normal draft were desired in the furnace, as for firing periods in a coal burning furnace. The parts would then move to the Imposition of Fig. 1, regardless of thermostat38, .and normal draft would be established. Upon reopening switch43, automatic control would be resumed.

What'we claim is: v 1. Control means for a furnace draft stabilizjing damper, comprising an electric motor adapt? ed while energized to be stalled without injury thereto, means operatively connecting said motor and said damper and having a stand-by. position for positively holding said damper in a minimum draft position and also having a release position for release of said damper for normal, draftstabilizing action; said connecting means comprising a lever operated by said motor and a bar connected with said damper and interengaging parts on said bar and lever automatically engaged when said parts are in release position and automatically disengaged when said lever leaves stand-by position, means for so disengaging them, spring means connected with said lever for moving the same to stand-by position, means for stalling said motor. when said lever reaches release position, and means energizing said motor only when the furnace demands additional heat. I

2. Control means fora furnace draft stabilizing dampencomprising an electric motor adapted while energized to be stalled without injury thereto, means operatively connecting said motor and said damper and having a stand-by position for positively holding said damper in a minimum draft position and also having a release position for release of said damper for normal draft stabilizing action, said connecting means comprising'a lever operated by said motor to release position and abarconnected with said damper, saidlever having a projection, said barhaving apin- 'and-slotmounting beneath said projection, said .bar having at its upper end ahook overlying said lever. projection when the parts are in release position, spring means for moving said lever to stand-by'position whereby said lever projection is moved upwardly and lifts said hook and bar;

keeper means engaging said bar in stand-by position, and said lever projection when leaving stand-by position moving in an are adapted to releasesaid hook whereby, after, release, said hook and bar may fall freely.

' 3. Control means for a furnace draft stabilizer damper, comprising an electric motor adapted while energized to be stalled without injury thereto, means operatively connecting said motor and said damper and having a stand-by position for positively holding said damper in a minimum draft position and also having a release position for release of said dampeiafor normal draft stabilizing action, said connecting means comprising a lever oscillatable by said motor from a stand-by position to release position, said con- 1 necting means' including reduction gearing,

spring means for moving said lever from release position to a stand-by position, which movement is retarded by' said gearing, said connecting means comprising disconnectible parts between said lever and damper, means causing disconnection of said parts by the first portion of said lever movement from stand-by position, whereupon gravity releases said damper for draft sta- 1 bilizing action, said disconnectible parts being again connected upon reaching release position,

and means energizing said motor only when said furnace demands additional heat.

l. Control means for a furnace draft stabilizing damper having operating and standby positions, comprising an operating element movable back and forth between two positions, motor meansfor moving it to one of its positions, power means for moving it to the other of its positions, operating connections between said element *means when effective energizing said power means and recoupling said coupling.

5. Control means for a furnace draft stabilizing damper, comprising an electric motor adapted while energized to be stalled without injury thereto, means operatively connecting said motorand damper and having a stand-by position for positively holding the said damper in minimum draft position and also having a release position for release of said damper for normal draft stabilizing action, said connecting, means including reduction gearing,.means o-peratively connected with said connecting means for moving the same to stand-by position against the inertia of said gearing, said connecting means also including disconnectible parts, means operative to disconnect said parts when said motor starts to move said parts from stand-by position toward release position, whereby said damper is then quickly released for normal. draft stabilizing action, said parts being so constructed and arranged as to be again operatively connected when in said release position, means for stalling said motor when said connecting means reaches release position, and means energizing said motor only when the furnace demands additional heat.

' MORRIS W. CREW.

GEORGE A. SHORT.

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