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Патент USA US2108873

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Feb. 22, 1938.
Filed July 17, 1934
2 Sheets-Sheet l
//\/4/5/\/ 777R
Feb. 22, 1938.
Filed July 17, 1934
2 Sheets-Sheet 2
Il/1 734 v.‘
Patented Feb. 22, 1938
Lawrence R. 'Teeple, Portland, Oreg.
Application July 17, 1934; Serial No. ‘735,617
'1 Claims.
This invention relates generally to underfeed
stokers, and particularly to a means for auto
matically controlling the amountoi air supplied
the form of a set screw 26.
to the combustion.
the compressor by the laterally extending pipe
the combustion zone of a furnace.
The second object isto provide a control means
10 to be efficient in its operation, devoid of compli
cations and at the same time capable of provid
ing any desired amount of lag between the com
mencement of fuel delivery and that of air de
These, and other objects, will become more ap
parent from the specification following as illus
trated in the accompanying drawings, in which
Fig. 1 is a perspective view of an underfeed
stoker equipped with my device.
Fig. 2 is a section taken along the line 2-2 in
Fig. 1 showing the pilot damper partly open.
Fig. 3 is a section taken along the line 3--3
in Fig. 1 showing the butter?y damper partly
holds the roller 24 against the eccentric 22 and
an adjustment is provided forthe spring 25 in
The main object of this invention is the pro
vision of an exceedingly simple and efficient form
of control for the air delivered by.the stoker to
Fig. 4 is a somewhat diagrammatic view show
ing the relation of the parts in detail with the
distance between the elements greatly reduced;
Fig. 5 illustrates the internal structure of the
air valve mechanism showing a position which
3.3 the parts. can assume under conditions different
than‘ those which are illlustrated in Fig. 4.
Similar numbers refer to similar parts through
out the several views.
Referring in detail to the drawings, there is
35 shown an underfeed stoker including the fuel
hopper ill, the fuel feeding tube II and retort l2,
to .which fuel is delivered from the hopper I!)
Air is admitted to
21 which communicates with an air ?lter 28.
‘The discharge end of the cylinder 20 is closed
by a bushing 29 which forms a- head therefor. .
Within the bushing 29 is disposed a ball check
30 which closes on the intake stroke of the com
pressor and forces the incoming air to be drawn 10
through the ?lter 28. The compressed air is
d‘scharged through a pipe 3| into ‘an oil ?lter
32 which may be of' any suitable type,’ pref
erably a simple container in which is disposed
a.fabric covered cage through which the‘ air 15
passes for the ‘purpose of removing oil there-.
from, from which it passes through a throttle
valve 33 provided with an adjusting screw 34.
The compressed air is ‘then carried to the T
?tting 35, one opening of which communicates 20
‘with the ‘bel1ows'36 which is supported by. the
The bellows
31 within
36 actuates
the casing
a rack
38. 38 which meshes ,
with a pinion '40 secured on the shaft 4| of a
butter?y damper i9 which can substantially close 25 '
the air duct l 5 when normal thereto.
The operation of ‘this portion of the device
is as follows: When the stoker motor I3 is op
erated, air will flow through the ?tting 35 into
the bellows. 36, causing it to open the butterfly 30
damper l9 and to remain open unless otherwise
effected, as will be explained later.
It is desirable to provide a spring 42. within
the casing 43 for returning the rack 39 to the
position shown in Fig. 4.
Turning now to the pilot damper I8 it will be
seen that same is: secured .to the shaft 44 on
which is secured a slotted indicator plate 45 from
through the tube II by means of a motor [3
which operates a screw (not shown); within the “ which projects a pointer 46 which is disposed
' 40 tube H. The motor l3 also operates a fan with
in the casing 14 and which delivers air through
the air duct i5 to the tuyere base i6 which sup
ports the retort l2.
Referring more particularly to myinvention
45 same will be seen to consist of an air compressor
unit [1 which is also driven from the motor l3,
' the pilot damper l8 and the butter?y damper IS.
The air compressor l'l may of‘ course be of any
desired type, ‘but for the purpose of illustration
50 ‘there, is shown a cylinder 20 within which opere
ates a piston 2|.
The piston 2l- is operated/by an eccentric 22v
whichis supported by the compressor block 23.
The eccentricv 22v acts'directly against a roller 24
_55 which is carried'by-the' piston~2l. The spring 25
alongside of the graduated 'cam 41, to which-‘it 40
is adjustably secured by means of the clamping
screw‘48. The end 49 of the cam 41 constitutes
a drop off or a low point, the purpose of which
will be explained presently.
The members 45 and 41 are mounted within a 45}
casing 50 which supports a pivot 5! on which are
\pivotally mounted the spring-urged arm 52, one
end of which rides against the cam 41 and the
other end of which is acted upon- by a spring 53
which re-acts against a second arm 54 which en- 50
gages a grooved collar 55 on the stem 55 which
carries an air valve disk 57. The disk 51 seats
over the outlet _58 of an air line 59 which con-I
nects° with the side outlet of the T ?tting 35.
The air line 59 is provided with a valve ‘60 hav- 55
lighter particles to be blown out of the retort [2
ing a relief opening Bl which is adjustably con
before they could be protected by the incoming
trolled by means of the set screw 62. It is neces
sary to provide an outlet opening 63 by means of green fuel.
It is for this reason that it is desirable to post
which air can escape from the outlet '58 when
pone the ?rst delivery of air until after the coal
the disk 51 is withdrawn therefrom.
feeding operation is well under way.
The operation of the device is as follows: As
The amount of lag can be controlled by the
suming that the stoker motor [3 is started in
response to any of the usual controls, the pilot adjustment of the screw 34 which does not effect
the pressure within the bellows 38, but the rate of
damper I8 having been at rest and the butter
air ?ow thereto.
10 ?y damper l9 being closed (as shown in Fig. 4)
I claim:
as the compressor I1 is operated vand pressure
1. A pneumatic control for air supply to a
builds up in_the ?tting 35 the bellows 36 be
stoker consisting of an air duct having a pilot
comes distended, moving the rack 38 and open
ing the butter?y damper l8, and the pilot damp-V damper mounted therein whose position is re
sponsive to the ?ow of air through said duct, a 15
er I8 is raised by the air ?owing past the butter
control damper within said duct for controlling
fly damper. This, however, does not happen in
stantaneously, there being an appreciable amount the ?ow of air therethrough, a pneumatic ace
of time between the moment the stoker starts tuator ‘for said control damper, an air supply
feeding coal and the moment it starts feeding
. '
controlled by the operation of said stoker for
air, and this time can be varied, as will be ex
operating said damper actuator, and. a cam op
plained. -
erated valve actuated by said pilot damper forv
As the pilot damper l8 continues to rise, un
3 der the increasing ?ow of air permitted by the
gradually opening butter?y damper I8, the cam
25 41 is carried with it-—that is, the end 49, whose
position can be regulated by the screw 48, de
sc'ends to a point which will permit the end of
the arm 52 to move, under the in?uence of the
spring 52—A, and, through the arm 54, open
controlling the pressure of air in said damper
2. The device described in claim 1, including
means for relieving the air pressure from the 25
damper actuator when the pilot damper is at a
position of rest.
3. ‘A device of the class described, the combi
nation of a fan, a motor for driving said fan, an
air duct conveying air delivered by said fan, a 30
pilot'damper within said duct actuated by air
passing therethrough, an adjustable cam actu
ated by said pilot damper, an air valve operated
by said cam, a control damper mounted in said
duct for controlling the flow of air therethrough, 35
direction, under the in?uence of the spring 42, a rack and pinion for operating said control
damper, an air operated actuator for said rack
until the butter?y [9 reduces the air ?ow sum
cientlytov bring about a sufficient drop of the ' controlled by said air valve, an air'compressor
damper I8, which will cause the cam 41 to again operated by said motor for delivering air under
pressure to said actuator, said air valve con 40
40 close the outlet 58.
*It can be seen from the foregoing that there stituting a means ‘for relieving the pressure from
is, produced by this arrangement a balanced con
said actuator when said .pilot damper is raised
,dition—that is, the attendant merely sets the above a predetermined position by an excessive
the outlet 58.
While the compressor I1 is sui?ciently large
to overcome the leak at the outlet ii to the extent
of operating the bellows 36, it is not able to do so
when the outlet 58 ‘is open, as stated, causing
the butter?y damper l8 to be moved in a closing
indicator pointer 46 at the desired mark on the
45 graduated cam 41, which represents a predeter
mined air ?ow, and this ?ow is maintained with
in very close limits, due to the fact that when
the ?ow exceeds,a predetermined maximum the
outlet 58 will be opened and the damper l9 will
50 be moved toward a closed position, and when the
?ow falls below a predetermined minimum the'
outlet 58 will be closed, causing the damper iii
to be moved toward an opening position.
It might seem that this would bring about a
55 rapid and continuous adjustment of the setting
?ow of air through said duct.
'4. The devicedescribed in. claim '3, together
with a means for continuously relieving the pres
sure from said actuator at a rate intermediate
the rate of delivery by said compressor and the ,
rate of flow through said pilot damper-actuated, ,,
air valve.
_, v
5. The device described in claim 1, together
with means for regulating the amount of air
which can be delivered by said compressor to said
damper actuator.
6. A pneumatic control for air supplied to 55
of the butter?y damper, but such is not the case
‘in actual practice since the action is by no means
stokers comprising an air duct having a butter- ’
instantaneous, the adjustments being slow and
?owing through said duct, a pilot damper which
is free to swing in said duct under the in?uence ~
?y damper for regulating the amount of _~air
of air passing said. butter?y damper, a pneumatic 60
actuator for opening said butter?y damper durtioning of the bellows 38, is to gradually relieve , ing the operation of the stoker in connection with
the pressure from the line 58 whenever the air which this device is used, spring means for clos
?ow through the duct l5 stops completely, due ing said butter?y damper in opposition to said
pneumatic actuator, a source of compressed air 65
65 to a stoker shut-down and the damper I8 is in
connected to said actuator by means of a pipe,
the position of rest (as shown in Fig. 4).
Unless this relief opening 6| was present, or an air valve communicating with‘said pipe be
there‘ was’ not enough natural leakage in the tween said butter?y actuator and its source of air
system, then the butter?y damper I! could re- . supply, means operated by said pilot damper for
opening said air valve during the passage of an 70
70 main in a partially open position during the shut
down so' that the next time the stoker ‘was excessive amount of air through said ductand
operated air would immediately pass the butter?y closing said air valve during the passage of a.
I9 and open the damper l8, producing an un
quantity of air which is less than a predetermined
desirable result, namely the delivery of air simul
minimum, a, throttle valve betweenthe source~
taneously with the delivery of fuel, causing the of air supply and said actuator for retarding the 75
The purpose of the relief opening 8| which, as
stated, is not large enough to prevent the func
opening of said butter?y damper for a prede
termined period after the commencement of air
trol damper, means for delivering air to said ac
tuator when said tan is operating, an air valve
delivery'to said butter?y actuator.
actuated by said pilot damper for releasing air
through said actuator when the velocity of the
7. In a. stoker the combination of an air supply
duct having a fan for supplying combustion air
thereto, a pilot damper in said duct responsive to
the ?ow of air therethrough, a control. damper
within said duct for controlling the'?ow of air
therethrough, a pneumatic actuator for said con
air exceeds a chosen value, and means for bleed
ing air from said actuator to permit the control
damper to close upon cessation of air ?ow to the
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