US2141711A - Automatic air control means - Google Patents

Description

Dec. 27, 1938. B. M. GLJTHRIE AUTOMATIC AIR CONTROL MEANS Filed Nov. 8, 1935 4 Sheets-Sheet 2 INVENTOR.

ATTORNEY.

Dec. 27, 1938. I 5 M GUTHR v2,141,711

AUTOMATIC AIR CONTROL MEANS Filed Nov. 8, 1955 4 Sheets-Sheet s -INVENTOR. BERIVHRDMORSE Gum/WE A TTORNEY Dec. 27, 1938. 1 B M GUTHRIE AUTOMATIC AIR CONTROL MEANS 4 Sheets-Sheet 4 Filed Nov. 8, 1955 INVENTOR.

E m a vb. m m fl N m E BY ATTORNEY Patented 27, 1938 NITED STATES AUTOMATIC AIR coN'rnoL MEANS Bernard Morse Guthrie, Chicago, Ill., assignor to Fairbanks, Morse & 00., Chicago, 111., a cor-.

- poration of Illinois App ication November 8, 1935, Serial No. 48,839

18 Claims.

lected embodiments thereof as applied to adomestic stoker assembly which may be of conventional form. It is to be understood, of course, that the particular application in no way limits the use of the improved automatic air control to stokers, as the control is adaptable to a variety of applications in other than stoker assemblies. In the drawings, Fig. 1 is a diagram showing a number of pressure-volume curves illustrating certain stoker air supply characteristics, as obtained experimentallyfrom testsmade upon a 20 stoker assembly having a constant speed blower supplying a forced draft of air to the tuyeres and retort of a domestic heating plant; Fig. 2 is a diagram of a plurality of pressure-volume curves obtained experimentally in the same manner as 25 were those of Fig. 1, but with the air supply under the control of an automatic air volume control mechanism embodying the improvements of the present invention; Fig. 3 illustrates an application of the control device of the invention to the air supply apparatus of a conventional domestic heating plant; Fig. 4 is an enlarged side elevation of a portion of an air supply conduit showing the air control mechanism mounted thereupon; Fig. 5 is a transverse section of the conduit presenting an end view of the assembled air control, as viewed from line 55 in Fig. 4; Fig. 6 is a transverse section of a portion of the control device as viewed from line 6-6 in Fig. 4; Figs. '7 and 8 are side and end elevations respectively, of a modi- 40. fied portion of the control device, the elevation of Fig. 8 being taken along line 8-8 in Fig. 7;

Fig. 9 illustrates a modified form of automatic air control device; Fig. 10 is a side elevation thereof,

shown partly in section, as viewed from line.

55 tary transverse section of the device, as viewed from line l5-l5 in Fig. 13; Fig. 16 is a transverse section of a portion of the control mechanism, as taken along lines l6l6 in Fig. 13, and Fig. 17 is a sectional detail elevation of a part of the device, as viewed from line lll'| in Fig. 16. 5

Fig. 3 illustrates a stoker assembly,-designated generally at l0, applied to a conventional domestic type of heating plant ll. The stoker assembly includes a fuel receiving hopper l2, a fuel conveyor l4 and conduit l5 enclosing the portion 10 of the conveyor extending between the hopper and the heating unit, an air blower shown in dotted lines at [6, an air delivery conduit l8 extending from the blower to the wind box IQ of the heaterunit II, and operating means (not 15 shown) for the stoker conveyor and blower. The heater unit includes a retort 20 provided with air tuyres 22. The stoker and heater organization described thus far may be of a type well known and widely used, but there are several disadvan- 20 tageous features of such an installation, particularly with respect to the heater air supply, which, heretofore, have caused considerable trouble in attaining uniform and eflicient combustion conditions in the heater.

Assume for purposes of illustration, that in the assembly above described, the stoker conveyor delivers fuel to the heater retort 20 at the rate of .6 pound per minute, and that the heat content of the fuel delivered averages 14,500 B. t. u.

persecond. Under normal heater conditions, the volume of air required for eflecting an efficient burning of this fuel would be approximately 128 cubic feet per minute. With a typical fuel bed substantially 8 inches in depth, it has been found by test that a static pressure equivalent to aproximately 1 inch of water, is required to force 128 cu. ft. of air per minute through the fuel bed. Assume now the stoker to be operating under the above stated conditions, with the blower operating at a constant speed to deliver air at the required pressure, and that after a period of such operation, the thermostatic or other. device controlling the operation of the stoker and blower in accordance with the heat requirements of the space to be heated by the heater unit, causes a cessation in the operation of the stoker and blower. The fuel in the furnace retort continues to burn at a slow rate of combustion, and fresh fuel is not delivered to the retort until the stoker 5o operation is again initiated by the thermostatic or other control acting in response to a call for heat. During the period of inoperation of the stoker and blower, at least a portion of the fuel bed will be consumed, and as the fuel burns, the so fuel bed becomes more porous so that it will offer less resistance to the flow of air therethrough when the blower again supplies air to the tuyres and retort. Since the blower operates at a constant speed, and since less resistance will be offered by the fuel bed to the passage of air therethrough, an excessive volume of air will now pass through the fuel bed. Under such conditions, the fuel bed will be disturbed and fly ash will be scattered and deposited over the heating surfaces of the furnace. Should the scattering of fly ash be excessive, the finer particles of ash may be forced out of the furnace into various parts of the house or space to be heated, thus creating a dust nuisance. Moreover, since fly ash is an effective heat insulator, the ash deposited over the heating surfaces of the furnace will form an insulating blanket which will result in greatly reducing the furnace efiiciency. Again, the excessive volume of air passing through the fuel bed will substantially prevent the building up of the fuel bed to the desirable depth of 8 inches, as above described, when the stoker again delivers fresh .fuel to the retort. This last effect is the result of a greatly increased rate of combustion as caused by an excessive volume of air traversing the fuel bed, so that fresh fuel fed to the furnace retort is consumed as rapidly as it is delivered thereto. Heating of the excess air in the furnace also tends to reduce the efliciency of furnace operation.

It is readily apparent from the above illustration that to overcome the noted disadvantageous features of stoker and furnace operation, some means for controlling the volume of air supplied to the fuel bed, under varying conditions of the fuel bed, must necessarily be employed. An airthrottle or damper of ordinary type which may be set to limit the amount of air delivered to the furnace to any desired degree, would give, under certain conditions of furnace operation, a fair degreeof combustion air control. But even with an ordinary damper in the air conduit, the volume of air delivered under varying conditions of the fuel bed, would not be regulated to effect the most desirable combustion conditions in the furnace.

Fig. 1 illustrates graphically the variation in volume of air delivered to the furnace fuel bed under varying pressure conditions of the bed, the several curves being obtained under different degrees of control of the air supply. It will be noted that the static pressure is given in inches of water and plotted as ordinates, while the volume of air is-measured in cubic feet per minute and plotted as abscissae.

Curve AC illustrates the result obtained with a constant speed blower supplying air to the furnace without an air feed control of any kind. The curve AC is obtained by establishing the point A independently of the stoker or any controlling means, the zero volume of air flow corresponding thereto, indicating a substantially closed duct or air system into which the blower discharges. Obviously, as resistance to the air how is decreased, due for example to decrease in fuel bed thickness or resistance, the volume of air delivered by the constant speed blower will increase, as indicated by this curve. The ordinate FB, representing a pressure of 1 inch of water, which is the normal pressure required for a fuel bed of 8 inch depth under the furnace and fuel feed conditions hereinabove described, is produced to intersect the curve AC at B. The

abscissa BN at this point of intersection, indie cates avolume of air of approximately 288 cubic feet per minute. As before noted, the normal volume of air required for efficient combustion is approximately 128 cubic feet per minute, so that with an uncontrolled air feed, the actual volume of air delivered tothe furnace is more than twice the volume required. The ordinate YDL representing the volume of air required for an efficient combustion of the fuel, being 128 cubic feet per minute, intersects the curve AC at point Y, and the ordinate FB at point D. The point Y indicates an excessive pressure while obtainingdamper in this instance, must be set so that when the fuel bed is approximately 8 inches in depth and offers a resistance to the flow of air therethrough of approximately 1 inch of water, the proper volume of air for eflicient combustion will permeate the fuel bed. For fuel having a heat content of 14,500 E. t. u., the proper volume of air and rate of air flow has been found to be approximately 128 cubic feet per minute, so that with the damper set properly, the curve AP may be made to pass through point D.

However, a damper having a fixed setting'is not satisfactory for all conditions of the furnace fuel bed, as will be observed from an inspection of the curve ADP. For example, as the pressure decreases, say as a result of the partial consumption of the fuel bed, the velocity of air fed to the furnace will materially increase, giving rise to the objectionable conditions heretofore noted.

Hence it will be readily understood from the foregoing discussion, that some means, preferably automatic, for controlling the volume of air fed to the furnace in accordance with the rate of fuel feed and the varying conditions of the fuel bed, is most desirable and practically necessary for obtaining an eflicient operation of the furnace. Such an automatic air throttling governor or air control is fully attained by the device embodying the present invention. In Fig. 3, the stoker housing is broken away as at 24, to reveal a preferred form of air control of the present invention, which may be designated generally as 25, applied to the air delivery conduit I8.

Again referring to the curves of Fig. 1, the curve ADE illustrates a characteristic of pressure-volume variation in the flow of combustion air which is greatly to be desired, for effecting an increase in the efiiciency of furnace operation under varying operating conditions. The degree of air volume control indicated by the curve ADE may be obtained with the improved automatic control device 25 embodying the improvements of the present invention. It will be noted that, for a variation in static pressure of from approximately .8 to 1.6 inches of water, the volume of air delivered to the retort and tuyres remains substantially constant. It will also be observed that as the pressure approaches a minimum, in-

dicating in many instances that the fuel bed is thin and about burned out, the volume of air delivered to the fuel bed actually diminishes, a

characteristic which is most desirable, as will be readily understood.

In the devices constructed according to the present invention, the structural elements of the regulators are so chosen and related that when adapted for the operation depicted by the curve AE of. Fig. 1, there is no appreciable restriction of air flow until there is attained a rate of 3 approximately 120 CFM. The pressure drop from 2.3 to 1.6 inches is substantially inherent in and incidental to the characteristics of the blower utilized. Under normal conditions this portion of the curve will not conform to actual stoker operation, the usual pressure ranges therefor lying between .5 inch and- 1.0 inch in the case of a stoker designed for air flow characteristics within the values indicated by Figs. 1 and 2.

As will be fully described hereinafter, the air control device of this invention is fully adjustable for effecting a control of the air feed under a wide variation in fuel bed conditions, rate of fuel feed, grades of fuel used, capacity of the furnace and other variable factors of furnace operation. Fig. 2 illustrates a number of pressure-volume curves obtained experimentally with different adjustments of the control device. Each of these curves has substantially the same form as that of the curve ADE shown in Fig. 1, and each has about the same characteristics of pressure-volume variation. The curve No. I corresponds to the curve ADE of Fig. 1, and indicates the air volume control for a furnace operating under the conditions hereinabove described. Curve No. 2 indicates the degree of air volume control for a furnace operating under different conditions than obtained for the curve No. I, such for example, as a different rate of fuel feed, a fuel bed having a normal depth greater or less than 8 inches, or a different grade of fuel used. Curve No. 3 was obtained under still different conditions of furnace operation.

As intimated hereinabove, the principal object of this invention is to provide a greatly improved automatic air control device which may have a wide range of uses, but which is particularly applicable to domestic stoker and furnace assem- 'blies for effecting an automatic and uniform control of the air. feed to the furnace tuyeres and fuel bed in accordance with changes in the combustion condition of the fuel bed.

Another object is to be found in the provision of a greatly improved air volume control device which is adapted to attain a regulation of the combustion airflow in accordance with the charin Fig. 1.

acteristic indicated by the curve ADE illustrated The deviceis fully automatic in its regulating function, and is capable of adjustment to provide for alterations in the grade of fuel fed to the furnace retort and the rate of fuel feed thereto.

A further object is to be found in the provision of an automatic air control device for the purpose described, which will give a uniform and smooth regulation of air feed, this result being attained through a novel arrangement of the elements of the assembly, so as to reduce or substantially eliminate any tendency for the control element to over-regulate through oscillation upon movement from one control position to another.

A still further object is to provide an improved control device for the purpose described, which is comprised of but a few elements each of which may be readily removed for repair or replacement,

the assembled control being sturdy and easily ad' e justable according to requirements therefor.

Yet another object is to provide, in an improved, automatic air volume control, means for readily effecting adjustments of the control mechanism to provide for changes in the rate of fuel feed and the grade of fuel used, the adjusting means including indicia of adjustment settings corresponding to the heat or combustion characteristics of the grade of fuel used, and the rate of fuel feed to the furnace.

Further objects and advantages may be found from the following description and from the drawings.

Referring now to Figs. 4, 5 ,and 6 by suitable characters of reference, the air control device generally designated as 25 is mounted upon a portion 26 of the air feed conduit l8. The device comprises a frame member 28 which is carried by the conduit section 26 and may be secured thereto as by the screws 29. One end 30 of the frame is provided with a portion 32 extending outwardly beyond the side wall 33 of the conduit ill, the extension supporting a depending arm ries an adjustable bearing element comprised of a pointed screw 40 threadedly engaging the supporting arm and provided with a lock nut 4| The bearing screws rotatably support a shaft 42, the shaft extending freely through suitable openings 44 in the side walls 33 and 38 of the conduit section 26 and having its ends jourrialled on the points of the screws 40 in a well known manner. An air-reaction element or damper plate 45 is non-rotatably secured to the portion of the shaft within the conduit 26, and is held in assembly therewith as by the screws 46.

Extending outwardly beyond the wall 38 of the conduit 26 is a portion 48 of the frame 28, this portion being, by preference, disposed on the frame end 49 opposite the end 30. The frame portion 48 supports spaced, depending arms 50 and 52 which may be formed each as an integral part of the portion 48. The arm 50 carries a bearing element in the form of an additional screw 40, threadedly engaging the arm and provided with a lock nut 4|. The arm 52 which is closely adjacent the conduit wall 38 as shown by Fig, 6, carries in fixed adjusted position, a pointed screw bearing element 54 which, by preference, threadedly engages the arm. The bearing elements 40 and 54 pivotally support one end of an arm 56 which carries on its opposite end a counter-balance or weight member 51. The weight 51 is shown in the drawings as being formed inteshaft and lever may be made in any suitable manner, such that movements of the damper plate 45 will effect responsive mo crrents of the lever. The free end 60 of the lever 58 by preference, operatively connected to the arm 56 carrying th weight 51, through an extensible structure such as the turnbuckle assembly 6|.

tax

The assembly 6| comprises oppositely threaded screws 62 and 64 threadedly engaging the end portions of a connecting link 65. The screw 62 is provided on its free end with an eye-portion 66 which is pivotally secured to the end 66 of the lever 58, as by a screw 68. The screw 64 similarly provided with an eye-portion 69, has this eye pivotally secured, as by a screw 10, to a portion ll of the'pivoted arm 56 intermediate the ends of the arm. Manually rotating the link 65 will effect an extension or retraction of the screw arms 62 and 64 in a manner which is well known. Through the adjustable link 65, the angular position of the damper plate relative to the weight may-be regulated at will, to provide for varying conditions of fuel feed and furnace operation.

As a means for limiting movement of the damper in the direction to reduce the flow of air through the conduit, a lug or stop element 61 is by preference formed on the bearing arm 31. the stop extending inwardly of the arm and in the path of movement of the lever arm 58 (Figs. 4 and 5). Thus, since the arm 58 is connected with the damper through the shaft 42, the arm 58 striking the stop 61 will effectively prevent further movement of the damper in the air flow cut-ofi direction.

The operation of the automatic air control is such that movements of the damper as effected by the air flow through the conduit I8, in the direction indicated by the arrow in Fig. 4, result in movements of the weight 51, the relatively large inertia of the weight, of course, tending to oppose any movement of the damper. The lever system between the damper and weight, comprised of the lever 58 and the adjustable lever 6|, is arranged to effect a greater angular movement of the weight than that of the damper plate, the preferred ratio of movement being approximately two to one. This multiplied movement of the counterbalancing weight 51 serves to prevent overregulation of the air supply upon changes taking place in the condition of the fuel bed. For example, if the angular movement of the weight were equal to that of the damper plate, then in the event of a change in the volume of air flow through the conduit, the

damper would be moved to counteract the increased volume of air and at the same time the weight would be moved. But because of its greater inertia, the angular swing of the weight will carry the damper beyond its position for proper regulation, and upon the return swing,

the damper will be carried beyond the proper position in the opposite direction. Thus an oscillation tends to be set up, resulting in an erratic control of the volume of air flowing through the duct. By providing a lever system between the damper and weight so that angular movements of the weight will be approximately twice as great as the angular movements of the damper, the tendency for the control device to oscillate will be practically eliminated. The increase in the inertia of the weight when its angular acceleration is increased, results in a greater dampening effect thereof, hence the damper will not respond quickly to slight variations in the volume of air flow and thus is obviatedan otherwise existing tendency to overregulate. It may be noted that a suitable dash pot or equivalent device (not shown by Fig. 4, but appearing in Fig. 13) may be employed in cooperation with the above described structure to assist in the control of damper movement for preventing overregulation of the combustion air.

It is to be understood that in the above described embodiment of the air control device and in the modifications thereof illustrated in the drawings and presently to be described, the dimensions of the damper element or air target, the mass of the counterweight and the leverage ratio of the mechanism operatively connecting the weight and the damper element, are definitely predetermined for control devices of a given capacity, so that the cooperative relation of the elements results in a control device which will give a form of combustion air flow regulation having the desirable characteristics illustrated by the curve ADE in Fig. 1.

Figs. '7 and 8 illustrate a modification of portions of the control structure shown in Figs. 4 through 6. For convenience, those elements appearing in the modified structure which have not been changed or modified over the corresponding elements shown by the preceding figures, will be 'given the same reference characters. The modified structure now to be described, provides an adjustment feature in addition to that afforded by the turnbuckle assembly 6|. The end of the damper carrying shaft 42 which is pivotally supported by the depending arm 31 of frame 28, supports a disc sector element 12, the element being secured at its axial end 14, to the shaft, as by a key connection 15, so that regulating movements of the air target or damper 45 will be transmitted to the element 12. The shaft 42 also supports a lever 16, the upper end 18 of which is freely pivoted to the shaft adjacent the end 14 of the element 12. The eye portion 66 of screw 62 is pivotally connected to the free end 19 of the lever I6, as by a screw 80. The lever 16 and sector element 12 must be operatively connected so that regulating movements of the damper plate 45 will be transmitted to the weight. This may be conveniently effected through a screw connection between the lever and disc element. The disc sector is by preference provided with a plurality of spaced, threaded holes 82 arranged along the peripheral portion of the sector in the manner illustrated in Fig. 7. The lever 16 carries intermediate its ends, a threaded bolt element 83 which passes freely through the lever and threadedly engages the sector, in any one of the holes 82, thereby efiecting an operative connection between the lever and sector element. The connection may be made selectively, in any one of the tapped holes 82, whereby to effect a change in' the angular position of the damper plate 45 with respect to the longitudinal axis of the lever 16, and which in turn will effect a change in the relative angular relation between the damper and the weight. Thus the angular relation between the weight and damper, in their normal positions of rest, may be initially or coarsely adjusted through the bolt connection between the lever 16 and sector element 12, and finally or more accurately adjusted by means of the turnbuckle assembly 6|. Movement of the damper in the direction to reduce the volume of air flow through the conduit is limited by a stop element 8| provided on the bearing arm 31, the stop by preference being in the form of a finger or lug extending into the path of movement of the sector element 12.

It is to be understood, of course, that in the above described adjustable arm and sector arrangement for efiecting initial or coarse adjustments of the damper element relative to the inertia element, the spaced, tapped holes 82 may be replaced by a continuous slot or recess of arcuate form (not shown), while the bolt 83 may be tion to the arm 16 and a slotted portion (not 9 through 12, employs a geared connection between the damper shaft and the weight shaft, the gears taking the place of the lever connections or linkage between the damper and weight shafts of the control device shown in Fig. 4.

The supporting frame for the elements of the latter modified control is comprised of a plate member 84 which is secured to the section 26 of the air supply conduit I8, as by the screws 86, and a box-like housing 81 which is secured to the end portion 88 of the plate 84, preferably by welding as at 90. The opposite end 9I of plate 84 extends outwardly beyond the conduit side wall 33 and downwardly as at 94 to provide a support for a bearing element 95. The bearing 95 may be $6- cured to the portion 94 in any suitable manner, preferably by welding as at 96. The outer side wall 98 of housing 8'! supports an adjustable bearing element comprised of a pointed screw 99 threadedly engaging a nut I and passing freely through the wall 98. The nut is fixedly secured to the wall as by welding at I02. The bearing elements 95 and 99 pivotally support a shaft I03 which extends through suitable openings I04 in the side walls 38 and 33 of the conduit 26. A damper plate I0! is secured to the portion of the shaft within the air conduit 26, preferably by the screws I08. The shaft I03 is by preference of square section over the greater portion of its length, as a matter of convenience in securing the damper plate thereto. The shaft end portion IIO adjacent the adjustable bearing 99 is preferably formed round and of reduced section,

- whereby to form the shoulder I I I. The shaft end IIO carries a gear element II 2 which is secured to the shaft against the shoulder I II in any suitable manner, such as by pressing the gear over the shaft end.

The housing 8! is provided with an inner side wall II4 overlying a portion of the conduit wall 38, and a slot I I5 is formed in the wall so that the wall may clear the shaft I 03. Referring particularly to Figs. and 11, the wall 4 supports a bearing element II6 which is fixedly secured to the wall preferably by welding, as at H8. The outer housing wall 98 carries an adjustable bearing comprised of a 'pointed screw element II9 threadedly engaging a nut I20 and passing freely through the wall. The nut I20 is secured to the wall as by welding at I22. The bearing elements H6 and H9 pivotally support a square shaft I23 having a rounded end portion I24 adjacent the bearing element I I6. The juncture of the square and round portions of the shaft forms a shoulder I26 for limiting axial movement of a pinion I21 carried by the rounded portion of the shaft. The pinion may be operatively secured to the shaft as by pressing it over the shaft end. In assembly, the pinion meshes with the gear I I2, so as to be operated by the gear, in response to regulating movements of the damper plate I01. The squared portion of the shaft I23 has secured thereto a depending arm I28, the upper end of the arm being welded to the shaft, as at I 30. The arm supports a weight element I3I which may be adjustably positioned along the arm, the weight being provided with a set screw I32 for securement to the arm in any adjusted position. The side wall II! of the housing, being the wall adjacent the counterweight supporting shaft I28, is cut away on its lower portion as at I2I, to permit the arm I28 to swing upwardly therethrough during regulating movement of the damper and weight mechanism. The marginal portion I25 of wall II1 defining the upper limit of the cut away portion I2I, serves as a stop for the arm or shaft I28, whereby to limit the swinging movement of the arm and counterweight, and hence of the damper element I01, in a direction to reduce the flow of combustion air through the conduit.

The operation of the modified air control is similar to that of the first described air control device, the increased movement of the weight relative to the movement of the damper being obtained through the gear and pinion, which may be formed to give a two to one ratio of movement. It will be apparent that the initial relative angular position of the damper and weight may be altered or adjusted to any desired degree, simply by meshing the pinion with the gear in the assembly of the control structure, in such manner as to effect the desired angular relation. 1 Figs. 13 through.1'7 illustrate a further modified air control mechanism embodying the improvements of the present invention. The control mechanism is, by preference, carried by a frame I34 which may be mounted upon a portion of the air supply conduit I8, and secured thereto as by the assembly screws I35. The frame is provided, near one end thereof, with laterally projecting arms I36 and I38, the arm I36 extending beyond the side wall 38 of the conduit I8 and the arm I38 outwardly beyond the opposite conduitfside wall 33. A bearing lug or member I42 is carried by the arm I38 adjacently to and extending substantially vertically below the free end of the arm. It is preferred to form the member I42 as an integral part of the arm, as shown in Fig. 14. The lug supports a bearing element in the form of a'pointed screw I43 which threadedly engages the bearing lug with the screw point directed inwardly thereof, toward the conduit. The bearing screw may be adjusted in the supporting lug, toward or away from the conduit, and may be locked in its adjusted position as by a lock nut I44. The arm I36 is provided, in a similar manner, with a bearing lug I46, an adjustable bearing element I41 and bearing lock nut I48.

The bearing elements pivotally support a shaft I 50 which extends laterally through the upper 110 (Fig. 16).

closed position, whereby to reduce the volume of air flow.

The portion ofthe shaft I59 located externally of the conduit I9 and extending between the conduit wall 39 and the bearing element I91, carries a frame member I55 of substantially U- shape, the frame being freely pivoted at its upper end I56, to the shaft in the manner illustrated by Figs. 13 and 14. Axial movement of the frame toward the conduit wall is, by preference, limited by a shouldered portion I58 on the shaft I59. The frame I55 comprises spaced, parallel arms I59 and I99, each provided-on its inner face with a longitudinally extending guide flange I62. The flanges are arranged in opposed relation as shown in Figs. 13 and 17, and support a member or block I63 for sliding movement longitudinally of the frame, the block having formed in opposite edges thereof grooves I 69 for the reception of the guide flanges. The sliding movement of the block is controlled preferably by a screw I66 threadedly engaging a lug I61 carried by the block as an integral part thereof as shown in Figs. 16 and 17. The screw is supported upon the frame I55 in a pair of spaced, parallel-bearing members I69 and H9, the members bridging the arms of the frame and formed, preferably, as an integral part thereof. The screw is provided, adjacent the screw head I, with a shouldered portion I12 which in the assembly of the screw to the frame, abuts the bearing member The opposite end portion II I of the screw is journalled in the bearing member I69, and is provided with a retaining lock pin I15 and washer I16 in abutting relation with the outer face of the bearing member. Thus the screw may be rotated freely in the bearing members, and without axial displacement thereof, as such movement is prevented by the shouldered portion I12 and the lock pin II5. Rotation of the screw in either clockwise or counterclockwise direction will, of course, cause the block I63 to slide along the frame I55 either toward or away from the pivoted frame end I56. The outer face portion II8 of the block is provided with a plurality of substantially rectangular recesses or grooves I19 for a purpose which will presently appear. As shown in Fig. 13, the several recesses are by preference, angularly or radially spread, fan-like, over the surface of the block.

The shaft I59 pivotally supporting the damper plate I52 and frame member I55, also carries an arm element I89 which has its upper end I82 engaging the shaft adjacent the end portion I56 of frame I55. The end portion I82 of arm I89 is secured to the shaft preferably through a key connection I83, so that pivotal movements of the damper plate I52 and shaft I59 will effect responsive pivotal movements of the arm I99. The free end I 89 of this arm carries a springactuated projection or plunger element I86 (Fig. 17) which is adapted to engage and seat in any one of the slots I'I 9 disposed in the face N8 ofthe block I63. The plunger assembly comprises a plunger-operating member or handle I8'l threadedly secured to the plunger element I86, a spring retaining barrel I88 secured to the free arm end I89, and a compression spring I99 seated in the barrel and having one end I9I abutting a flanged portion I92 on the Barrel, and its opposite end I99 seated "against a flange element I95 carried by the plunger. The structural features and operation of the plunger-assembly presently described and illustrated; are well known, and hence need not be described further herein,

It will be readily seen that the plunger in engagement with any one of the slots in the block element I63, forms an operative connection between the arm I99 and the pivoted frame I55, whereby air regulating movements of the damper plate will be transmitted to the frame I55. The rectangular slots in the block I63 permit the block to be adjusted along the frame I55, while the plunger operatively engages any one of the slots, the purpose for this adjustment feature appearing hereinafter.

The frame I55 is provided with an outstanding lug portion I96 on the arm I69, serving asa pivotal seat for one end I98 of a rod or link element I99, the opposite end 299 of rod I99 being pivotally connected to an arm .292 supporting an inertia element 293. The pivotal connection of the rod end I99 to the lug I96 is, by preference, made through a friction-reducing structure such as the ball bearing assembly 299, the outer race 296 thereof being carried by the lug I96, while the inner race 291 is secured to the rod end I98 as by the bolt 298 and securing nut 2I9. As shown in Fig. 14, the rod end I98 is furcated so as to embrace opposite sides of the lug I96, to facilitate connection thereof to the inner race element 291. The pivotal connection of the rod end 299 to the weight arm 292 is by preference, effected in a similar manner, through the friction-reducing assembly 2! I, the bolt 2I2 and securing nut 2M. However, in this instance, the outer race of the assembly 2 is carried by the rod end 299, while the inner race is secured to the weight arm, as by the bolt 2I2 and nut 2M (Fig. 15)

The free end 2 I5 of arm 292 carrying the inertia element 293, is pivotally connected to an outstanding bearing arm 2| 6 carried by and forming a part of the frame I39. The bearing arm 2 I6 is arranged on the end portion of the frame opposite, and is parallel to, the frame end I36 supporting the bearing arm I96. The pivotal connection of the arm 292 to the bearing arm. 2I6 is by preference, effected through a friction-reducing journal assembly, with the outer race element 2I9 thereofseated in a portionof the bearing arm 2 I 6, and the inner race 229 secured to the end 2I5 .of arm 292 as by the bolt 222 and clamping nut 223.

In the last described embodiment of the invention, the lever system connecting the counterbalancing weight 293 with the damper plate I52, comprised of the arm I89, frame I 55, lever I99 and weight arm 292, is arranged to efiect a greater angular movement of the weight than of the damper plate. This multiplied movement of the counterweight serves to prevent overregulation of the air supply in the manner hereinbefore described. As a further means for preventing overregulation of the air supply, it is preferred to apply an additional or secondary movement-retarding force to the lever system. This additional retarding force may be very efiectively obtained through the application of a suitable dash-pot device to the lever system. A dash-pot of conventional form is shown at 225 in Fig. 13, wherein the cylinder 226 thereof is pivotally supported at one end upon a pin 22? carried by suitable bearing lugs 229 secured to the frame I39. The dashpot piston rod 239 is pivotally connected on its free end 23I to an arm 232 extending laterally of and formed as a part of the lever I99. Thus displacement of the lever I99 resulting from regulating movement of the damper I52 will be retarded to a desirable degree by the dash-pot 225 operating As before described, the operative connection.

in conjunction with the counterbalancing weight 203.

As in the previously described embodiments of the invention, movement of the damper plate I52, in the direction to reduce or cut-off the flow of air through the conduit, is limited by a suitable stop device. In the present example, the stop device comprises a lug or abutment 234 carried by the frame I34, and a projection 235 formed on the arm I80 and arranged to engage the lug as the arm swings to'the left (Fig. 13). As the arm I60 is operatively connected to the damper I52, engagement of the projection235 with the lug 234 will effectively prevent further movement of the damper in a clockwise direction about its pivotal support I50.

' The air control operation of the modified device presently described, is similar to that of the control devices earlier referred to, and hence such operation need not be repeated. It will be observed from the arrangement of the several elements comprising the control device, that movements of the damper element I52, as eifected by changes in the volume of air flow through the conduit 'I8, will be transmitted to the inertia element 203, the inertia element of course,'tending at all times to counteract such movements of the damper plate. As hereinabove intimated, the provision of the U-shaped frame I55, slidably carrying block I63, and the several slots "9 arranged in the block for receiving the plunger element carried by the damper arm I80, serves to permit the adjustment of the control mechanism in accordance with predetermined operating conditions of the stoker and heater assembly to which the control device is applied. For example, the thermal value of fuels vary, so that if a grade of fuel having a heat value of 14,000 B. t. u. per pound is delivered at a given rate to the furnace retort, a certain volume of air per unit of time will be required for the efiicient combustion of such fuel. Hence, the initial setting of the damper plate must be such as will permit the required volume'of air to flow to the furnace retort and tuyeres. For a different grade of fuel having say a heat content of only 12,000 13. t. u. per pound, the initial setting of the damper plate must be adjusted so that the correct volume of ,air will be delivered for eflicient combustion of this grade of fuel. effect different initial settings of the damper plate, is made through the sliding block I63, which when actuated by the screw I66, will effect a change in the angular position of the damper within the conduit I8. The effect of this adjustment is to change the initial relative angular relation of the inertia element and the damper plate.

To facilitate proper adjustment of the control device for the purpose above described, suitable f indicia of control settings, indicated at 224, are arranged in scale form, say along an inner marginal portion of the arm I60'of the U-shaped frame, (Fig. 13). The setting of the block I63 relative to the scale 224 is indicated by a suitable notch or pointer 226 disposed on a marginal portion of the block opposite the scale. The scale 224 is by preference graduated in units of fuel heat content or B. t u.s per pound, and its calibration is effected in accordance with a predetermined relative position of the sliding block I63 and its supporting frame I55, corresponding to the initial angular position'of .the damperelement I 52 required to admit the desired volume of air for the efficient combustion of the particular r grade of fuel burned.

The adjustment of the control device to.

between the damper plate and the sliding block is effected through the damper arm I carrying the spring-pressed plunger I86 which is adapted to engage any one of the rectangular slots I19 in the face of the sliding block. It will readily be seen that by changing the plunger connection from one slot to another, the angular setting of the damper plate relative to the inertia element,

I will be altered. For convenience in effecting adjustment of the control devicefor different rates of fuel feed, the several slots I10 are numbered I, 2 and 3 from left to right, the numerals indicating optimum damper settings corresponding to different predetermined rates of fuel feed. Thus when theplunger element I86 carried by the damper arm I80 is engaged in the slot designated by the numeral I, the damper plate will be angularly set relative to the inertia element for regulating the air supply in accordance with a predetermined rate of fuel feed. Engaging the plunger in slot 2 adjusts the damper to control the air supply in accordance with a second predetermined rate of fuel feed, and so on.

While only three slots are shown in the sliding block I63, it is to be understood that the number of slots may be increased where it is desired to effect adjustments of the air control for a greater number of different rate-s of fuel feed.

Adjustment of the control device then, to effect an automatic control of the air supply to the furnace tuyeres in accordance with a predetermined rate of fuel feed and the grade of fuel used, may'be readily and easily effected simply by seating the plunger I86 in the slot corresponding to the predetermined rate of fuel feed and adjusting the sliding block I63, through screw I66,

so that the match mark 226 is disposed in alignment with the particular division of the scale 224 corresponding to the predetermined heat content of the fuel delivered to the furnace. The effect ofthe above described adjustment is 'to vary the initial angular setting of the damper plate relative to the inertia element, so that in the operation of the heating plant, the control device will automatically regulate. the volume of air supplied to the fuel bed in accordance with changing conditions in combustion.

The operation of the device illustrated by Figs. 13 through 1'7 is thought to be apparent from the description of operation of other embodiments of the invention, but may be briefly described as follows: Any appreciable increase in rate and volume of air flow in the direction of the arrow (Fig. 13) tends to move the damper element I52 in a direction to restrict the area of opening through this portion of the duct. Such movement of the damper element is opposed, through theconnections described; by the inertia element 203, so-

'that any substantial movement of the damper takes place only by shifting the position of the inertia member. Once the several adjustments of the device of Fig. 13 have been effected in accordance with heat value of the fuel and predetermined rate of fuel feed, the linkage connecting the damper I52 to the inertia element will operate substantially as if there were a rigid arm connecting the damper pivot to the end I98 of arm I99, whereby there is provided, with advantages noted, a motion-multiplying connection between the damper and inertia element. It results from this that as the damper is displaced in a direction to restrict the flow of air, the inertia element is displaced from its normal position of rest to an even greater extent, so that the arrangement disclosed serves efficiently to prevent hunting or overregulation. The parts are so selected and operatively related, as in certain of the preceding embodiments, as to result in pressure-volume characteristics substantially as shown by the curve ADE of Fig. 1.

The several embodiments of the invention described hereinabove and illustrated by the drawings, fully attain the foregoing objects, and in addition, each of the several constructions is sturdy and dependable for a fully automatic operation thereof, requiring little or no care once the mechanism is adjusted according to particular requirements of furnace operation.

It is to be understood, of course, that the presently described embodiments of the invention may be altered or modified without affecting the spirit and full intended scope of the invention, as defined by the appended claims.

I claim:

1. In a stoker assembly, an air supply conduit, an automatic air throttle including a target damper in said conduit, a swingably mounted weight, for yieldably opposing operation of said target damper, an adjustable connection between the damper and the weight adapted for increasing the effect of the weight during air throttling operation of the damper, and a dash pot also connected to the damper and tending to suppress movements thereof in response to changes in movement of air through the conduit.

2. In a stoker assembly, an air supply conduit, an automatic air throttle including a target damper in said conduit, a swingably mounted weight, a dash. pot, a motion-amplifying connecting linkage between the target damper and the dash pot and weight, and means associated with said linkage for adjusting the relative normal positions of rest, of the damper and the weight.

3. A draft regulating device comprising in combination with an air conduit, a frame, a draft control member carried by the frame and arranged in said conduit for regulating air movement therein, in response to the flow of air through the conduit, an inertia member pivotally carried by the frame and tending to oppose regulating movement of said control member, and motion-amplifying means forming an operative connection between said members, said means including a plurality of elements, one thereof being adjustable for regulating the initial operative relation of said members relative to each other. I

4. In combination with a stoker assembly including a retort, a source of air supply and a conduit for conveying air from said source to the retort, an air control element in said conduit,

,responsive for its control operation to the flow of air therethrough, angularly displaceable inertia means tending to oppose operation of said control element, and means forming an operative connection'between said opposing means and control element, and adapted to increase the effect of said opposing means during control operation of said element, said last means being adjustable for regulating the initial operative relation of said opposing means and control elesive for its regulating movement to the flow of air through the conduit, an inertiamember pivotally carried by the frame and tending to oppose movement of said regulating member, and motion-amplifying means operatively connecting said members and 7 adapted for increasing the efiect of said inertia memberg during movement of said regulating member, said means including a plurality of elements, at least one thereof being adjustable for regulating the initial angular relation of said members relative to each other.

6. A draft regulating device comprising in combination with an air conduit, a draft control member in said conduit arranged for control actuation in response to the flow of airthrough the conduit, a swingable inertia member tending to oppose regulating movement of said control member, and motion-amplifying means operatively connecting said members, and including a lever and an extensible linkage structure pivotally connected to the lever and to the inertia member.

7. In combination with a stoker assembly including a retort, a source of air supply and a conduit for conducting air from said source to the retort, a frame, a draft control member carried by the frame and arranged for pivotal movement in said conduit, said member being responsive for its regulating movement, to the flow of air in said conduit, an inertia member pivotally carried by the frame and provided for opposing means forming an operative connection between said members, said means including an element pivotally actuated in response to regulating movement of said control member and an extensible device pivotally connected to said element and to the inertia member.

8. In a stokerassembly including an air supply conduit, an automatic air throttling governor assembly including an air target rockably disposed in the air supply conduit, a damping device rockably mounted on an axis spaced from that of the target, a linkage for translating movement of the target to the damping device, adjustment means providing for a coarse or substantial variation of initial angular position of the target, and a distinct device adapted to permit a finish adjustment between the target and the damping device.

9. In an air throttling governor assembly for use in the air supply conduit of a coal stoker, an

air reaction element in the conduit, an inertia element, said elements being rockably mounted for movement about spaced axes, a motion amplifying connection from the air reaction element to the inertia element, means providing a coarse adjustment of the initial angular setting of the air reaction element relative to the inertia element, and means providing a finer or finish adjustment of such angular relation.

10. A draft control device comprising in combination with an air conduit, a draft control member in said conduit, responsive for its control movement to the flow of air through the conduit, an inertia member tending to oppose control movement of said control member, and means including a pair of coacting rotary elements, forming an operative connection between said members, said means being adapted to increase the effect of said inertia member during control movement of said control member.

11. In combination with a stoker assembly including a retort, a source of air supply and a conduit for conducting air from saidsource to the retort, a draft regulating element in said conduit responsive for its control movement to including a projection and means recessed to the flow of air through said conduit, 2. frame, an

inertia element pivotally carried by the frame and tending to oppose movement of said regulating element, and means forming an operative connection of gear type between said elements and arranged for increasing the efiectof said inertia element during control movement of said regulating element.

12. In combination with a stoker assembly including a retort, a source of air supply and a conduit for conducting air from said source to the retort, a draft regulating element in said conduit, responsive for its control movement to the flow of air through said conduit, a frame, an inertia element pivotally carried by the frame and tending to oppose movement of said regulating element, and adjustable means forming an operative connection between said elements and arranged for increasing the effect of said-inertia element during control movement of said regulating element, said means including rotatable elements carried by the frame, said elements being detachably connected in selected relations for effecting adjustment of said connecting means.

13. A draft control'device comprising in combination with an air conduit, a draft regulating member in said conduit, responsive for its control movement to the flow of air through the conduit, an inertia member tending to oppose control movement of said regulating member, and means forming an operative connection between said members, said means including an element actuated in response to movements of said regulating member, a lever mechanism and an adjustable device connecting said element to said lever mechanism.

14. A draft control device comprising in combination with an air conduit, a draft regulating element disposed in said conduit and responsive for its control movement to the flow of air therethrough, an inertia element tending to oppose control movement of said regulating element, a member actuated in response to movements of said regulating element, a member operatively connected to said inertia element, and an adjustment device serving to complete an operative connection between said members, said device provide a plurality of seats for said projection.

15. In combination with a stoker assembly including a retort, a source of airsupply and a conduit for conducting air from said source to the retort, a draft regulating element disposed in said condu it and responsive for its control movement to the flow of airtherethrough, an inertia element tending to oppose control movement of said regulating element, a member actuated in response to movement of said regulating element, and adjustable means connecting said member to said inertia elementand forming with said member an operative connection between said elements, said means including a guide member, an element slidably adjustable in said guide member and having grooves therein, and a. retractable plunger operatively engaging a groove in said slidable element.

16. In combination with a. stoker assembly including a retort, a source of air supply and a conduit for conducting air from said source to the retort, a draft regulating element disposed in said conduit and responsive for its control movement to the flow of air therethrough, a frame, an inertia element tending to oppose control movement of said regulating element, pivotally carried by said frame, a member also carried by said frame and arranged for pivotal movement in response to control movement'of said regulating element, and means associated with said member and forming an operative connection between said elements, adapted for increasing the effect of said inertia element during control movement of said regulating element, said means including a guide member pivotally carried by the frame, an element adjustably carried by said guide member and detachable means operatively connecting said adjustable element to said member.

1'7. In combination with a stoker assembly including a retort, a source of air supply and a conduit for conducting air from said source to the retort, a frame, a draft regulating member carried by the frame and arranged for control movement in said conduit in response to the flow of air through the conduit, an inertia member pivotally carried by the frame and tending to oppose control movement of said regulating element, an arm also carried by the frame and movable responsively to control movement of said regulating member, means associated with adjusted settings.

18. In combination with a stoker assembly including a retort, a source of air supply and a conduit for conducting air from said source to the'retort, a frame, a draft regulating member carried by the frame and arranged for control movement in said conduit in response to the flow of air through the conduit, an inertia member tending to oppose control movement of said regulating member, pivotally carried by the frame, an arm also carried by the frame and movable responsively to control movement of said regulating member, and means associated with said arm and forming therewith an operative connection between said members, said means comprising a guide member pivoted to the frame, a lever connecting the guide member to said inertia member, an adjustment device slidably carried by said guide member and provided with grooves in a face portionthereof, and a removable element carried by said arm and adapted to seat in any one of said grooves, for operatively connecting the arm in adjusted relation to said device.

BERNARD MORSE GUTHRIE.

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