US2893485A

US2893485A - Control devices for fluid fuel burners

Info

Publication number: US2893485A
Authority: US
Inventors: Russell F Garner
Original assignee: Robertshaw Fulton Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1955-08-16
Filing date: 1955-08-16
Publication date: 1959-07-07
Anticipated expiration: 1976-07-07

Description

July 7, 1959 GARNER 2,893,485

CONTROL DEVICES FOR FLUID FUEL. BURNERS Filed Aug. 16, 1955 2 Sheets-Sheet l v 10 24 Fla. 1.

110 155178 7 105,110 120,124 p L I 122126 19 1*" 9 105110 1721m R. F. GARNER CONTROL DEVICES FOR FLUID FUEL BURNERS Filed Aug. 16, 1955 July 7, 1959 2 Sheets-Sheet 2 INVENTOR. IZUSSZLLF [17AM 1116' ATIUEMET' States Patent 2,893,485 CONTROL DEVICES FOR FLUID FUEL BURNERS Russell F. Garner, Youngwood, Pa., a'ssignor to Robert- Shaw-Fulton Controls Company, Greensburg, Pa., a corporation of Delaware Application August 16, 1955, Serial No. 528,763

4 Claims. 0. 161---9) and timing means for incinerators and the like.

It is a principal object of this invention to arrange a main burner 'valve, an afterburner valve and a timing mechanism for sequential operation of the valves within a a single casing.

Another object of the invention is to utilize a common element for actuating the valves and adjusting the timing mechanism.

Another object of this invention is to arrange the parts compactly while insuring ready access for servicing.

Another object of this invention is to utilize a mechanical escapement mechanism of relatively fragile construction to control relatively large forces.

"Dhis invention finds particular utility in combined timed valves for fluid fuel burning incinerators of the type having a main burner and an afterburner located in the flue or stack.

In apparatus of this general character, a main burner is 2,893,485 Patented July 7, 1959 utilized to control flow of fuel to fluid fuel burners. The control device is shown as comprising a casing 10 provided with an inlet 12 which is adapted to be connected to a source of fuel now '(not shown), an outlet 14 communicating with a chamber 16 and adapted to be connected to an afterburner (not shown) and an outlet 18 which is adapted to be connected to'a main burner (not shown).

A valve chamber 20 is formed interiorly of the casing 10, adjacent the inlet 12, by a longitudinal extending wall 22 integral with and projecting from one end wall 24 and a rectangular wall'26 extending transversely of a side wall 28 of the casing 10. 'Ihewall 22 is centrally bored at 30 to form a passage for conveying fluid fuel from the inlet 12 to the chamber 16 and is provided with a valve seat 32. A disc valve member 34 is mounted on a valve stem generally indicated by the reference numeral 36 for movement therewith between open and closed positions relative to the seat 32. The valve member 34 is normally biased toward the seat 32 by a coil spring 38 held in compression between the lower surface of the valve member 34 and a closure cap 40 threaded in the side Wall 28.

The valve stem 36 has an axial bore 42 extending from one end for the greater portion of its length and shaped I to slidably receive a centering pin 44 carried by the cap utilized to burn various disposals placed therein, and an afterbumer which heretofore was separately controlled, usually manually, was employed to effect combustion of the gases expelled from the main'burner chamber. In this manner, the obnoxious vapors and gases expelled from the main incinerator chamber are burned in an r afterburning chamber or flue to reduce somewhat the obnoxious character before such gases reach the outside atmosphere. In the prior art, separate controls were employed for controlling the flow offuel to the main burner and afterburner and for the most part, these are manually actuated.

In the preferred embodiment of the invention, a pair of valves and an actuator therefor are arranged within a single casing to control fuel flow to a pair of outlets.

A timing mechanism is operatively connected to the actuator for opening one of the valves to permit fuel to flow to only one outlet during a first predetermined time interval. At the end of this interval, the other valve is adapted to be actuated to an open position where it remains during a second predetermined time interval to v aliect fuel flow to both outlets. Upon termination of the second time interval both valves are moved to the closed position. 7

Other objects and advantages will appear from the following specification taken in conjunction with the accomi vice is shown as applied to a valve casing of the type I 40 for guiding the reciprocable movement of the valve member 32. An external thread 46 is formed at the opposite end of the valve stem 36 and has an adjusting nut 48 threaded thereon. I

An outlet valve chamber 50 is formed interiorly of the casing 10 remote from the inlet 12 and adjacent the outlet 18 by a longitudinal inner wall 52 integral with and projecting from an end wall 54 of the casing 10 and an inner wall 56 extending transversely from the side wall 28. The wall 52 is provided with a passage 58 for conveying fuel from the chamber 16 to the outlet chamber 50. An annular valve seat 60 is formed on one side of the wall 52 around the passage 58. A disc valve member 62 is mounted on a valve stem, generally indicated by the reference numeral 64, for movement therewith between open and closed positions relative to the valve seat 60. The valve member 62 is normally biased toward the seat 60 by a coil spring 66 held in compression between the lower surface of the valve member 62 and closure cap 68 threaded in the side wall 28. A centering stem 67, similar to the stem 44, is mounted in the cap 68'and extends into the valve stem 64 which is suitably recessed for this pulpose. An adjusting nut 69 is threaded on the opposite end of the valve stem as in the case of the nut 48 on the valve stem 36.

v Means'for moving the valve members 34 and 62 relativeto the valve seats 32, 60, respectively, is provided and is here shown as a centrally pivoted lever 70-operativel-y associated with the valve stems 36 and 64. The

\ lever 70 is adapted for operative engagement with the

nuts

48 and 69 and is rotatable upon a shaft 72 which extends transversely through the casing 10 and is secured to the side walls thereof by any suitable means.

In Fig. 1, the valve members 34 and 62 are shown in their normal positions, that is, the valve member 34 is biased into engagement with the valve seat 32 and the valve member 62 is out of engagement with the seat 60. To establish these relative positions, the biasing strength of the spring 38 is made correspondingly greater than that of the spring 66 such that the spring 38 biases one end 74 of the lever 70 to elfect a clockwise rotation thereof and force the valve member 62 away from its seat 60.

Means for rotating the lever 70 to move the valve members 34 and 62 relative to their seats 32 and 60, respectively, is provided and is here shown as including an actuating member 76 operatively engageable with that arm 77 of the lever 70 adjacent the valve member 62. The actuating member 76 comprises a shaft 78 which extends slidably through suitable openings 80, 82 in the casing and is normally biased outwardly by a light coil spring 84 held in compression between a retaining washer 86 slidably receiving the shaft 78 and a collar 88 secured thereto. The wall 56 and a transversely extending inner wall 89, substantially parallel therewith, define a recess 90 for receiving the spring 84 and the shaft 78 and is provided with suitable packing 92 between the washer 86 and one end of the recess 90 adjacent the opening 80 to prevent the escape of fluid fuel from the chamber 16.

The actuating member 78 projects outwardly from the casing 10 and is recessed at one end 94 to loosely receive the end of a plunger 96. The plunger 96 extends slidably through a housing 98 mounted on the casing 10 in axial alignment with the shaft 78 and is loosely retained at one end to a shaft 100 which is adapted to rotate and to translate relative to the housing 98. Secured to the end of the shaft 100 which extends out of the housing 98 is a manually operable knob 102 for imparting such movements to the shaft 100. Suitable indicia 104, indicating the on-01f positions of the valve members 34 and 62 are imprinted on the edge of the knob for registry with any suitable reference mark on the housing 98 for a purpose which will more fully appear hereinafter.

Secured to the inner end of the shaft 100 is a plate 106 which carries a pair of oppositely disposed abutment means or followers which take the form of projections 108, 110 extending from the plate 106. A relatively stationary detent member is engageable with the projections 108, 110 for limiting axial movement of the shaft 100 and comprises a generally annular cam assembly 112 secured to the inside of the housing 98. The cam assembly 112 includes a radial flange block 114 which is adapted to be seated in a suitable recess 116 formed in the housing 98 and retained therein by screws (not shown).

As shown in Fig. 2, an annular body portion 118 extends axially inwardly from the flange 114 concentric with the shaft 100 with the end portion thereof being shaped to define a first pair of axially spaced

helical surfaces

120, 122 having equal helix angles for cooperation with the follower 108 and a second pair of axially spaced helical surfaces 124, 126 having equal helix angles for cooperation with the follower 110. The helix angle and lead of the surfaces 120, 124 are equal and oppositely disposed with respect to the shaft 100. In the same manner, the helix angle and lead of the

surfaces

122, 126 are equal and oppositely disposed with respect to the shaft 100.

Angular extensions of the surfaces 120 through 126 may be of any suitable values depending upon particular timing cycles and timer mechanism used as will become apparent hereinafter. For purposes of illustration only and without limiting the scope of the present invention, the cam surfaces 120 and 124 extend through approximately 40 while the

surfaces

122 and 126 extend through approximately 90.

As shown in Fig. 2, the

surfaces

120 and 122 are axially spaced, being separated by a drop-off or wall 128. Similarly the axially spaced surfaces 124, 126 are separated by a wall 130. Each of the

surfaces

122 and 126 terminates in a

recess

132, 134, respectively, which are substantially diametrically opposed with respect to each other and are adapted to receive the followers 108, 110. A stop projection 136 is located adjacent the surface 120 remote from the wall 128 for limiting rotational movement of the follower 108 in one direction. A second stop 138 located adjacent the surface 124 remote from the wall 130 limits the rotational movement of the follower 110 in one direction. It will be apparent from the above description, that for any position to which the follower 108 is moved with respect to the

surfaces

120, 122, the follower 110 will occupy a similar position with respect to the surfaces 124, 126 diametrically opposed to that of the follower 108.

A stop plate 135 is secured to the inner surface of the flange 114 and includes a pair of diametrically opposed stop plates 137 (only one of which is shown in Figs. 1 and 2) which guide the positioning of the followers 108, 110 upon the surfaces 120, 124, respectively. Each of the plates 137 are formed with an edge 139 for a purpose to be described hereinafter.

The shaft 100 extends slidably and rotatably through the open center of the annular cam assembly 112 so the; the axial movement of the shaft 100 in one directio limited by engagement of the followers 108, 110 with the cam assembly 112.

The length of the

shafts

78 and 96 is such that, when the followers 108, 110 are positioned within the

recesses

132, 134, the spring 38 will hold the lever 70 in the position shown in Fig. 1 wherein the valve member 34 is in the closed position and the valve member 62 in open position. However, when the shaft 96 is moved axially to move the followers 108, 110 out of the recesses 132, 13 3, the actuator shaft 78 is moved against the bias of the

springs

84 and 38 to space the valve elements 34 and f in various controlling positions as will appear hereina lif the shaft 100 is rotated after it has moved the val members 34 and 62 to their various controlling positiof the followers 108, 110 will engage the helical surfac 120, 124 and the valve members-34 and 62 will be retained in their controlling positions.

' It will be apparent that the axial thrust exerted on the

shafts

78 and 96 by the spring 38 by way of the lever 7 3 will be transmitteddirectly to the shaft 96 and to tne followers 108, 110 carried thereby. Since the

helical surfaces

120, 122, 124, 126, are disposed at an angle to the line of action of this force, a portion of the force will be transformed to torque and will tend to rotate the sh- 100 with accompanying slidable movement of the followers 108, 110 down the surfaces120, 122, 124, 126. However, the helical surfaces 120 through 126 will ex a reactive force on the followers 108, 110, a portion of which will comprise a torsional component acting in a direction to resist such slidable action of the followers 108, 110.

It is an important feature of this invention that the coacting surfaces of the followers 108, 110 and the re tively stationary cam assembly 112 be so arranged tl the operating force acting upon the movable member will produce a component of force substantially equal in magnitude and opposite in direction to the reactive component of force resulting from friction between the surfaces regardless of the magnitude of the operating force of the spring 38. With such an arrangement, an extremely small force may be utilized to disengage the movable element 96 from the stationary or detent element 112.

It is desirable that the frictional or resistiveforce resulting from the friction between the follower 10S and the

surfaces

120, 122 be equal to the component of force acting parallel to the

surfaces

120, 122 which tend to move the follower 108 along the same. This relationship may be stated in another Way: The helix angle which the helical bearing surfaces makes with a plane perpendicul r to the axis thereof is made such that the tangent thereof of the helix angle between the'bearing surfaces 124, 126

and the axis thereof is substantially equal to the coefficient 55 bf friction of the coacting surfaces of the followe r 110 and the surfaces 124,126.

From the foregoing, it Will be apparent that the total torque acting on the shaft 100 as a result of the axial load thereon will be determined by the summation of the tendency toward slidable movement produced by the engagement of the followers 108, 110 with the helical surfaces 120 through 126 and the tendency to resist slidable movement therebetween. Thus,'rotation of the shaft 100 may be effected by the application thereto of a relatively small torque without regard tothe magnitude of the axial thrust on the shaft 52. t

Means is provided for applying a control force to the valve actuating means to effect-release of the movable operating member 96 from'the detent member 112. This means takes the form of "an escapement control-led clock movement 140 disposed within the housing 98 and mounted therein by any suitable means. 1

The movement 140 may be of any conventional type "and is here shown as including a driven gear 142 which meshes with a pinion 144 and being :adapted to receive the shaft 96 so that the samemay move axially relative to the pinion 144 while a torque transmitting relation is maintained therebetween. This connection is here shown as comprising a first leaf spring 148 secured at its medial portion to the pinion 144 and a second leaf spring '146 secured at its medial portion to a boss .150 which in turn is secured to the shaft 100 and the plate 106. The juxtaposed ends of the leaf springs 146, 148 are connected together tat 152 so that rotational-movement will be transmitted between the pinion 144 and the shaft 100 but, upon axial movement of the shaft 100, the springs 146, 148 will flex, causing no axial displacement of the pinion 144. V i

' Operation I When no fuel is flowing to .either the main burner or the afterburner, the various parts of the control device are positioned as shownin Fig. 1

To place the control devicein operative condition, the actuator 78 is moved axially against the bias of the

springs

38 and 84 by manual manipulation of'the knob 102 to the position wherein the followers 108, 110 are moved out of the recesses 132,134 beyond the outer extremities of the helical surfaces 120 through 126. The knob 102 is then rotated slightly until the followers 108, 110 engage the outer surface of the stop plates 137. The stop plates 137 serve to hold the plate 106 and the followers 108, 110 away from the

helical surfaces

120, 126 during a time-setting operation. Rotation of the knob 102 is continued until the followers 108, 110 slip off the rear edges 139 of the plates 137 and on to the surfaces 120, 124 respectively. Further rotation of the knob 102 is effective to move the followers 108, 110 along the surfaces 120, 124 until the same abutthe stops 136, 138, respectively, as shown in Fig. 2.

In such position of the plae' 106, the lever 70 occupies the position shown in dotted lines A in Fig. l, the valve member 34 is in the position shown in dotted line B and the valve member 62 is in the position shown in dotted line C. In these positions of the valve members 34 and 62, fuel will flow from the inlet 12, into the chamber 20, around the valve member 34, into the chamber 16, through the outlet 14 and to the afterburner (not shown). Since the valve member 62 is in engagement with the valve seat 60, fuel will be'prev'ented from flowing into the chamber 50 to the outlet 18. I

:As hereinbefore pointed out, the helix angles of the helical surfaces 120, 124 are such that the tendency towards rotational movement of the shaft 100 is balanced by the frictional force'resisting such movement. The shaft 96 will, therefore, remain in the position in which it has been set unless an additional torque is applied thereto to start rotation of thesame and move the followers indicated in the dotted line F in Fig. l.

108, 110 down the surfaces 120, 124 tow ard the

recesses

132, 134 respectively.

The rotational setting movement of the knob 102 also rotates the pinion 144 which drives the gear 142 and winds the mainspring (not shown) of the clock movement 140. When the knob is released, the torque of the mainspring is transmitted directly to the gear 142 and the pinion 144, the escapement mechanism (not shown) of the timer movement 140 controlling the speed of rotation of the pinion 144, the plate 106, the shaft and the knob 102 to their initial angularpositions.

In the original setting of the knob 102, the followers 108, are positioned adjacent the

stops

136, 138 as shown in Fig. 3 in the solid line position D. After a predetermined time interval, depending upon the angular extension of the surfaces 120, 124 and the speed of the timer movement 140, the mainspring (not shown) will rotate the shaft 100 and the plate 106 and move the followers 108, 110 to the positions shown indotted line E. In moving to these positions, the shaft 96 has moved axial-1y a distance indicated at F and consequently permitted clockwise rotation of the lever 70 to the position It is at this position of the lever 70 that the same is adapted to contact the upward extremity of the stem 64 when the valve member 62 is in the closed position. Rotation of the lever 70 from the position occupied at A to that position occupied at F has permitted the valve member 34 to move from the'position occupied at B to the position indicated at H under the bias of the spring 38. Thus, the valve member 34 remains open for permitting fuel to flow to the outlet 14, and the valve member 62 remains closed since rotation of lever 70 from position A to position F does not move the valve member 62 from its position C.

In the positions indicated at E, the followers 108, 110 are disengaged from the helical surfaces 120, 124 and, since the followers 108, 110 are then in alignment with the walls 128, 130, the shaft 96 will be moved rapidly to the right, as viewed in Fig. 1 for a distance indicated at I (Fig. 3) until the followers 108, 110 engage the

helical surfaces

122, 126 adjacent the walls 128, 130 at the positions indicated at K. Simultaneously with this axial movementof the shaft 96, the lever 70 will rotate in a clockwise direction and occupy the position indicated in dotted lines L under the bias of the spring 38. This movement of the lever 70 actuates the valve member 62 away from its seat 60 to "a position indicated in dotted lines M and moves the valve member 34 toward its seat 32 as indicated in dotted lines N. In these positions of the valve member 34, fuel continues to flow from the inlet 12, around the valve member 34, into the chamber 16 and through the outlet 14. With the valve member 62 disengaged from its seat 60, fuel will be permitted to flow from the chamber 16 around the valve member 62, through the outlet 18 and to a main burner (not shown). Thus, it will be apparent that in these positions of the followers 108, 110 and the shaft 96, fuel flow to both main and afterburners will be conducted simultaneously.

Continued rotation of the shaft 100 and the plate 106 under the torque of a mainspring (not shown) of the timer movement moves the followers 108, 110 along the

surfaces

122, 126 to the positions indicated in dotted lines 0 (Fig. 3) after a predetermined time interval set by the angular extensions of the

surfaces

122, 126 and the speed of the timer movement 140. In the movement of the followers 108,110 to the positions indicated at O, the shaft 96 will have moved a distance P to permit further clockwise rotation of the lever 70 to the position indicated in the dotted lines Q. The. gradual timed rotation of the lever 70 to the positionvQ has moved the valve members 34 and 62 to their dotted line positions R, S respectively and fuel continues to flow through both outlets 14 and 18. It is to be noted here, that with the valve member 34 in the position indicated at R, maxi- 7 mum flow of fuel is permitted to flow around the valve member 34 as is the case when the valve member 62 is in the position indicated at M.

In the position indicated at O, the followers 108, 110 are disengaged from the

helical surfaces

122, 126 and, since the followers 108, 110 are then in alignment with the

recesses

132, 134, the shaft 96 will be moved rapidly winding'of the mainspring is prevented. Thus, the mainspring will never be permitted to run down and a substantial torque may be exerted thereby on the shaft 100 in all angular positions of the shaft 100 to eliminate any danger of insufficient winding of the main'spring when the timer is set to operate at a small time interval. It is to be noted that since the followers 108, 110 are diametrically opposed to each other, they will engage and disengage the helical surfaces 120 through 126 simultaneously thereby preventing possible tilting and binding fo the shaft 96.

It will be apparent from the foregoing that the illustrated embodiment provides a new and improved control device which permits sequential timed actuation of a plurality of control valves for controlling the fuel flow to a plurality of burners, all within a single casing. It will also be obvious to those skilled in the art that the illustrated embodiment may be variously changed and modified, or features thereof, singly or collectively embodying other combinations than those illustrated without departing from the scope of the invention or sacrificing all of the advantages thereof, and accordingly the disclosure herein is illustrative only and the invention is not limited thereto.

I claim:

1. In a control device, the combination comprising a pair of control means movable between a plurality of positions and biased to one of said positions, lever means pivoted intermediate opposite ends thereof, said ends being operatively engageable with said control means respectively, a shaft movable into operative engagement with said lever means for causing movement of said control means against said bias to another of said positions, means defining a plurality of pairs of helical cam surfaces, each of said plurality of pairs being provided with relieved portions, follower means movable with said shaft and engageable with said surfaces for holding said control means in said other position, and means operable for rotating said shaft for imparting slidable movement to said follower means relative to said surfaces to move said follower means into registry with said relieved portions and permit at least one of said control means to move under said bias to said one position.

2. A control device as claimed in claim 1 wherein said follower means include bearing surfaces adapted for frictional engagement with said cam surfaces, and means for applying a force to said follower means tending to impart slidable movement to said bearing surfaces relative to said cam surfaces, said surfaces being constructed and arranged to render said frictional engagement effective to produce a resistive force tending to prevent said slidable movement substantially balanced by the force tending to produce said slidable movement.

3. In a control device, the combination comprising a casing having an inlet passage, a first outlet passage and a second outlet passage, a main valve member having open and closed positions for controlling a flow of fuel vinto said casing though said inlet passage, a second valve member having ,open and closed position for controlling the flow of fuel from said casingthrough said second outlet passage, a pivoted lever having one free end to cooperate with-said main valve member and an opposite free end to cooperate with said second valve member, a main biasing spring'exerting a force on said main valve member in opposition to the one free end of said lever, a second biasing spring exerting a force on said second valve member in opposition to the opposite free end of said lever, said main biasing spring exerting a greater force than said second biasing spring so that said lever is pivoted to a position where said main valve member is biased to said closed position and said second valve member is biased to said open position, an actuating member engaging saidlever to cause pivotal movement thereof, a shaft operatively connected to said actuating member and having manual means thereon for moving said shaft in one direction whereby said actuating member pivots said lever so that said main valve member is actuated to said open position and said second valve member is, actuated in said open position and said second valve member is actuated in said closed position, cam means operably associated with manual means for controlling the'movement of said shaft in another direction, and follower means movable with said shaft and engageable with said cam means for controlling the movement of said shaft in said other direction whereby said actuating member causes pivotal movement of said lever so that said main valve member and said second valve member both assume their open positions.

4. In a control device, the combination comprising a housing having an inlet and an outlet passage for fluid defining a pair of valve seats, a pair of inlet and outlet valve members movable between open and closed positions relative to said seats respectively, said housing having a second outlet for fluid intermediate said inlet and the first said outlet, lever means pivoted intermediate opposite ends thereof, said opposite ends being operatively engageable with said valve members respectively, means for biasing said valve members to one of said positions, said biasing means being effective on said lever means for causing rotation thereof in one direction, a shaft movable into operative engagement with said lever means for causing rotation thereof in another direction, means defining a plurality of pairs of cam surfaces coaxial with said shaft, one of said pairs of surfaces being provided with axially extending recesses, a pair of followers movable with said shaft into said recesses for locating said shaft in a first-axial position wherein said lever means position said outlet valve member in said open position while said inlet valve member remains biased to a closed position, manually operable means secured to said shaft for imparting axial movement thereto to move said followers out of said recesses and to rotate said lever means in said other direction'to position said inlet valve member in said open position and cause movement of said outlet valve member to said closed position, said manual means being operable for imparting rotational movement to said shaft and positioning said followers in engagement with one pair of said surfaces to hold said lever means against further rotation, said second outlet receiving fluid from said inlet while said first outlet is closed, and means operably associated with said manually operable means for rotating said shaft for imparting slidable movement to said followers relative to said surfaces, said slidable movement causing said followers to move axially from one of said pairs of said surfaces to another of said pair of said surfaces and thereby causing rotation of said lever means in said one direction sufiiciently for actuating said outlet valve member to open position while said inlet valve member remains in open position and to move said followers subsequently into registry with said recesses and said shaft to said first axial position.

(References on following page) 10 References Cited in the file of this patent 2,012,532 Grayson Aug. 27, 1935 UNITED P ENTS 2,459,583 Peter Jan. 18, 1949 956 860 Lawler STATES AT May 3 1910 2,778,419 Want z Jan. 22, 1957 978:0 Minlos "Dec 1910 5 2, m e l- 1957 1,570,685 Larrabee Jan. 26, 1926 FOREIGN PATENTS 1,605,471 Schenk Nov. 2, 1926 1,395,904 Laven b 7, 1933 86.513 swltlfirland p 1920 1 922,945 Greis Aug, 15, 1933 167,392 Great Britain 11, 1921