Feb. l l, li.
2,233 ,635
F. R. Newsom
Filed Jan. 5o, 1939
. 2 sheets-sheet l
J6
17
Feb; 1 1, 1941.'
F. R.` NELsoN
2. ,231
STOKER AIR CONTROL
Filed Jan. 50,1939
2 sheets-sheet 2
atentos! Feb. 1l, 1941
2,231,635
NITED STATES
PATENT y OFFICE
2,231,635
STOKEB 'Am CONTROL
Floyd R. Nelson, Rockford, Ill., assigner to Cotta
mission Corporation, Rockford, Ill., a
corporation of'lllinois
Application January 30, 1939, Serial No. 253,631
8 Claims. (Cl. 23S-_45)
This application is a continuation in part of
Fig. 3 is a longitudinal section through the
. my application Serial No.~ 69,944, iiled March 20.
1936.
5
.
This invention relates to stokers and has par
ticular reference to a novel means for controlling
the volume of air delivered to the retort of an
underfeed stoker.
.
The principal object of my invention is to pro
vide a damper in the air conduit, the position
. .o O of which changes due to variation of back pres
sure in the conduit whereby tò automatically
15
structure of Fig. 2;~
`
Fig. 4 is a cross-section on the line 4-4 of
Fig. 3;
'
Fig. 5 is a side view of another air control 5
generally similar to that shown in Fig. 2;
Fig. 6 is a longitudinal section through the
structure of Fig. 5;
'
Fig. 7 is a cross-section on the line ‘I-'I of
Fig. 6, and.
`10
Fig. 8 is a sectional detail on the line 8-8 of
open the damper wider when resistance to the
passage of air through the fuel bed increases,
Fig. 7.
and vice versa.
responding parts throughout the views.
`
Another object is to provide an oscillating
vane linked to the damper and mounted so as
to tend to gravitate to a position corresponding
to the fully closed position of the damper and
arranged to be raised more and more with in
20 crease in back pressure in the conduit to ac--`
‘
Similar reference numerals are applied to cor
The stoker appearing in Figure 1 has the con- 15
ventional `hopper 5 to store the coal which is
fed through a conduit 8 into the bottom of the
retortfl. The coal fed to the retort rises therein
to maintain a desired depth of fire bed, the coal
being fed from the hopper through the conduit 20
cordingly open the damper wider and wider, ' by a screw in the usual way. The screw is driven
whereby to maintain a substantially constant through reduction gearing in the housing 8 by
flow of air through the fuel bed regardless of an> electric motor indicated 'in dotted lines at
9, the same being disposed behind the blower
varying bed conditions, arising either from vari
25 ation in the coal fed to the retortA or variation housing I0. Simultaneously with the feeding 25
in the amount of clinker allowed to accumulate. of coal to the retort, air is discharged tan
l Still another object consists in the provision
gentially from housing I0 through the down
wardly inclined neck II into the air conduit I2
and conducted into the retort 1, whereby to
30 justed manually to suit the requirements of a supply sufficient air to the ñre bed for good com- 30
given installation, according to the kind of coal bustion. In the past, various typœ of air con
to be burned and the depth of ilre bed to be trols have been provided, some involving merely
a manually adjustable damper or shutter and
maintained, this valve determining by its adjust
others involving dampem or shutters intended
r ment the normal degree of rise of the vane and
accordingly the normal or mean condition so. to be adjusted automatically to suit conditions. 35
Most of the automatic controls with which I
far as the amount of damper opening is ccn
vcerned. A special feature in this connection is am familiar have been rather complicated and
the mounting of the oscillating vane in eccentric expensive, and, on the whole, not very reliable.
relation to the arcuate wall of the air chamber Then too, most of them if adapted to meet one
conditionjwould not take care of others apt to 40
so as to have increased clearance for air flow
arise
in service, with the result that they have
past the vane the farther it moves upwardly not given
satisfaction. The air control of vmy
and opens the damper more and more, whereby invention is one Vwhich is simple and inexpensive,
to secure the desired responsiveness and sensi
and, when once manually adjusted to suit the
tivity and insure against movement of the damp
requirements of a given installation, automatic- 45
er past the point to which it should be adjusted ally adjusts itself thereafter to varying bed
to suit a. given condition of the fire bed.
conditions, to the end that the stoker is kept
The invention is illustrated in the accompany
operating efiìciently at all times.
`
ing'drawings, in Which-¿y
According to my invention, a damper I3 is
of an air chamber for the vane, having an ad
I
50
justable air bleeder valve arranged to be ad
Figure 1 is a side view of a stoker installation
in which the air conduit of the stoker `embodies
an air control made in accordance with my in
vention;
i
Fig. 2 is an enlargement of the air control
55 portion of Figure 1;
mounted on a horizontal shaft I4 in the neck II 50
for oscillatory movement. The screws I5-I‘6
have conical seats receiving the conical ends of
the shaft I4 with a free Working iit to insure '
smooth and easy turning of the damper. A
pointer I1 is ñxed to the shaft I4 outside the 65
È
assises
neel; ii and moves relative to e gradua
When the temperature drops suihciently for the
indi
cetor plete is' to indicate the degrœ of
oí the damper. This pointer points to “9" whe
the domper is closw. iand to “5" when the
per
thermostat to start the stoker again.' the in
coming sir from4 the blower housing i@ gradually
raises the vane 2i ond opens the demper i3 and.
is fully opened.
depending upon the adjustment of the valve 20,
the damper is will assume a certain position o!
An arm is on the damper is
has a link tu attached thereto connecting the
demper with the actuating vane si. The vene
is designed to work by air pressure, as s piston
or diaphragm, except that its movement is oscil
latory. It is mounted on a horizontal shaft 22
received with e free working fit in bearings 23
in the opposite sides or" a segmental houding 2e
csrried on top of the neck il adjacent the bend
partial opening, where it is in equilibrium, with'
the pointer il at one of the numbered positions
between 0 and 5, or at some position between
two numbers. The setting of the valve 2B is l0
made to suit the requirements of the installation,
according to the hind of coal to be burned and
the depth of fire bed to be maintained. The thing
that determines the position of the damper It is
the back pressure in conduit I2, which acts on 15
the vane 2i, and, obviously, if the air valve 28 is
adjusted so that sir passing around the edgœ of
therein. The vane 2i hss o certain amotuit of
clearance between the edges thereofy and the side
and end walls of the housing, es clearly oppears
in Figs. 3 and e, so that while this vene will he
deñected upwardly under air premure from be
heath, air will pass around the edges of the vane
20 and escape from the housing through the slot
this vane is allowed to escape freely, so that a
greater pressure differential exists between the
opposite sides of the vane, the vane will rise 20
higher and accordingly open the dampery I3
wider. Now, assuming that the valve 28 has .
25 more or less freely depending upon the od
justmenti of a bleeder valve 2t. The latter may
be of any suitable or preferred type and, in this
case, is in the form of a round rod received with
a close working ñt in the elongated bearing 2i
provided on the top wall of the housing. One
been set so that under normal conditions the
demper is will open to an extent where the
pointer i‘i is opposite say the numeral 2,»nnd, 25
due to, let us say, an inñux of finer coal than
usual, the resistance to air flow through the
iìre bed is increased: this will result in raising
the vane 2i a trifle higher and accordingly the
damper i3 will be opened wider to admit more
sir to meet the demand. In other words, the
control meters the volume of air required for a
certain fuel bed. In that w`ay, good combustion
is secured. By the same token, if more than the
usual amount of clinker is left on the `ilx‘e bed
and the resistance to 'air ñow through the ñre
side oi? the rod has a hat milled thereon, es in
dicated at 23, so that as the rod is turned, more
or less of the slot 25 is opened to the atmosphere
80 through another elongated slot 2@ in the well of
'the bearing 2l. The rod 2o has e. pointer t@ on
the enlargedend thereof,- which moves relative
to graduations 3i on the side wall of the housing
2t to indicate the position of the vulve. The
35 'housing 2t will preferably be csst in one piece,
as e. die casting, for economy and to insure the
desired accuracyof nt of the vane 2i therein.
bed is accordingly increased, the damper I3 will
This housing is shown as fastenedby means of
screws 32 to the wall of the neck ii over the
be opened wider automatically to take care of
the need for increased volume of air. This air
40 openingk 33 therein, und a gasket 3s interposed
between the parts metres for an slr-»tight con
control,l in other words, compensates automati 40
cally for varying fuel bed conditions and thereby
insures keeping the Stoker operating eillciently
et sli times. It is manifest that the air control
nection. The vane 2i, owing to the position oi
the housing tends to grsvitete to the lowermost
position in which itis shown in Fig. 3, and, while
involves so few parts and these are of such -simple
and durable construction that there is very little
likelihood of the mechanism getting out of order
and requiring attention. A few simple instruc
tions will enable the user to make whatever ad
45 it takes very little air pressure upon the vene
to cause it to start rising, it is manifest that
more and more pressure is required to raise the
vane the nearer it approaches a horizontal posi
tion. Now, the vane will reach substantially a
statiaily fully opened and pointer il points to
justments may be desirable. Usually, the valve
2S when once properly set according yto instruc
tions will not require any readjustment unless
“5.” i may' provide en_arm 3€ on one end of.
the shaft 22 adiustelbly secured by means of e.
decides upon maintaining a different depth of
horizontal position when the damper i3 is sub
set screw 36, to permit placing it at any desired
55. angle relative to the vane, and having a plurality
of spaced holes il into any one oi7 which a screw
su; may be entered to fasten s counterweight or
Weights 39 closer to or farther from the axis of
oscillation oi’ said vane. In this wey, any def
60 sired operating characteristics so far as the
operation of the'vane 2i -is concerned may be
obtained, and more or less air pressure will be
required to bring the vane to a certain position.
In operation, whenever the usual room thermo
65 stat stops the stoker because the heat demand
has been satisñed, the vane 2i gravitates to the
position shown in Fig. 3 and closes the damper
i3, thus leaving the fire bed dependent upon the
small 'amount of air that will seep past the
damper i3, and what air will find its way through
openings in and around the ñre door of the fur
nace. The fact that the damper is closed makes
for economy because the coal will naturally burn
slower under those conditions, and it also makes
75 for mtter comfort by avoiding overheating.
the user changes to some other kind of coal or
rire bed.
y
'
f
`
While I have disclosed a damper I3 in the air 55
conduit operated by the vane 2l to meter the
volume of air delivered to the retort 1, it should
be evident that the same results could be ob
tained by leaving the vane 2| where it is and
substituting for the damper a shutter on the 60
air intake t0 on the blower housing I0 to meter
the intake of air to the blower. Obviously, the
volume of air delivered to the retort would be
varied in the same Way by such a shutter oper
ated in response to movement of the vane 2l. 65
The claims should be construed accordingly, the
word “damper" used therein being considered in
its broad sense as referring to any air control
or metering member, such as a shutter.
Referring now to Figs. 5 to 8, in which the nu
merel I la designates the end of the air discharge
neckvon the blower housing and |2a designates
the. adjacent end portion of the air conduit
through which air is delivered to the ñre bed,
this air control, like the other, involves an oscil
p
a
23315635
lating vane `21a operatively connected with a i weight- is requiredl or a different position of ad- -
damper itay through the medium oi a linkv 20a.
The‘vane. 2la, like the ,vane 2|, is arranged to
be operated by air pressure to communicate move
justment thereof. This‘indicates that there is
a relationship between the Avaneis clearance and
the counterbalancing force of the weight, and it
ment_to the damper, the segmental- housing 24a is clear, therefore, that what happens when the »
fire vbed develops resistance to air flow through
in which the vane operatesbeing in communica
tion. with the air .conduit through the opening 33uv it and requires a -wider opening of thedamper
so as to subject vthe Avaneto whatever static pres
sure- existsin theair conduit. Asln the Vair con
10 trol first described,`a slot 25a permits escape of
aix-‘from> that space in the housing behind the
vane, and air will pass -around the -edges of the
vane -and out through the slot more or less freely
depending upon the adjustmentor the bleeder
valve 26a, which, in the presentflnstance, is inE
the form'oi a dat strip otfsheet metal pivoted
on a screw 40 at .one end ~for oscillatory adjust
ment relative to-.the slot 25a and >arranged to be
held in adjusted position‘by means of a set screw
20 4I threaded in the cover plate 42 mounted on the
housing 24a and arranged to be locked by'means
of a lock nut 43. The end of the valve 26a_projects through a. slot 44v in one Aend of the cover
plate `42 to permit manual adjustment thereof
when the set screw 4l is loosened and obviously
the position of the valve in relation to the slot is
a suillcient indication ofthe adjustment, because
.when the valve is in a mid-position in the. slot.
as _shown in» Fig. 8, the slot- 25a is half covered.
The vane Zia in the present structure is coun
terbalanced by a weight 45 iixed by means of a
set screw 46 in the proper position of endwise
, adjustment relative to an L-shaped arm 41 car
is this: The' increase in back pressure in the
air conduit I2a acting on the vane 2Ia, which
up to that time was in a balanced position‘oi' 10
equilibrium, causes the vane to move in a clock
wise direction, opening thedamper wider, the
vane moving upwardly to a pointwhere, -due to
the greaternclearance between the vane and the
wallj48,~ there is a sufficiently increased ilow of 15
air possible past the vane-'and out through the
slot 25a to establish a new position of equilibrium
with the counterweight 45 also exerting a greater
counterbalancing eil’ect by reason of its shift in
position with the damper. Actual experience 20
shows that when the vane has moved to a certain
point and adjusted the damper accordingly, it
will lnot b_e balanced in any other> position one
way or the, other from that position. For ex
ample, if one moves the pointer -Ila one way or 25
the other from the self-assumed position, it will
' invariably come back‘to exactly that position,
thus showing clearly that the parts’ are imbal
anced in any other position" and therefore return
to the previous self-assumed balanced position. 30
Itis believed the foregoing description con
veys aI good understanding of the objects and
>advantages of my invention.
The ` appended
ried on A'the pointer lla fixed to the shaft,_l4
carrying the damper I3a. The portion of the
arm 41 carrying the weight 46 lsparallel' to the
claims have been -drawn with a view to covering
pointer l'la, and hence when the »weight ls ad
justed along the arm, itslradius .with relation to
l. A stoker air control comprising a damper
mounted within an air conduit for delivering ait
under pressure to a stoker retort, said damper
having oscillatory movement from a position clos
ing the opening therethrough to another posi
tion substantially opening said conduit, a seg
the shaft I4 is changed and its counterbalancing
valuel is increased or decreased. In the clock
wise `movement of the vane 2Ia„ the counter
weight V45 _is moved ln a 'counterclockwise direc
tion through` a. correspondingV angularity and
Vtherefore exerts a greater and greater c_ounter
balancing effect theffarther the vane is raised.
Now, it is important to .note that the >center 22a
about which the vane 2la oscillates is slightly
eccentric relative to the `arcuate 'inside wall 48
of the housing 24a. This is indicated in Fig. 6
by the fact that'the dot-and-dash arc af--b de_
all legitimate modiñcations and adaptations.
I claim:
'
as
.i
mental-shaped housing communicating with said
conduit adjacent thedamper, a gravitating vane
mounted for oscillatory movement in said hous 45
_ing and operatively connected with said’Y damper
so as to close the damper when the vane is in
lowermost position,„said vane being operable with
a predetermined clearance in said housing to per
mit air flow from the conduit _into the housing 50
and past said vane, whereby said vane is adapted
` scribed by the outer end of the vane in its move- Y
ment is in closer spaced relation to the arc 48 at to be raised by increased pressure in said conduit
va than at b. In actual practice, the housing 24a togopen said damper and lowered upon a decrease
in pressure to close said damper, the vane and
is preferably die cast with the bearing holes 49 housing
being formed and disposed relative to 55
for the shaft 22a eccentric just a few thousandths one another so as to increase the sizeof the air
of an inch, so that the clearance between the passage between the vane and housing as the
outer end 50'of’the vane 2 la and the arcuate wall vane moves ín'a direction to open t'he damper,
K 48, at b, is just a few thousandths oi’ vaninch and adjustable means for permitting discharge
greater than at a. This varying clearance has of air to the atmosphere from said housing from 60
(ill
proved to be very important in` securing the de
sired responsiveness and sensitiveness and forin
suring -accurate movement> of the damper and
behind the vane therein.
4
2; A stoker air control comprising a damper>
mounted With-in an air conduit for delivering air
preventing movement past a certain point to . under pressure to a. Stoker retort, said damper
which the damper should be adjusted to suit a having oscillatory movement from a position clos 65
given condition of the bed.I I have found that ing the opening therethrough to another position
this varying clearance is directly responsible for substantially opening said conduit, a segmental
l'the stopping of. the vane VZla at a; certain posi „shaped housing communicating with said con
tion when there is a change in the fire bed, due duit adjacent the damper, a gravitating vane
to a sudden influx of “fines”, for example, or, mounted for oscillatory movement in said hous 70
due to an accumulation of ashes or clinkers, and
ing land operatively connected vwith said `damper
y a wider openingv of the damper is required and
so as to close the damper when the vane is in
is produced automatically. I have found that ' lowermost position, said vane being operable with
if a greater variation in clearance is provided a predetermined clearance in said .housing to per
mit air flow from the conduit into the housing 75
between points a and b, a different sized counter
4
9,231,635
.
and past said vane, whereby said vane is adapted
communicating with said conduit adjacent the
to be raised by increased pressure .in said con
duit to open said damper and lowered upon a
ment in said housing and operatively connected
damper, a vane mounted for oscillatory move
decrease in pressure to close said damper. the
with said damper, said vane being movable with
5 vane and housing being formed and disposed rela
tive to one another so as to increase the size of
the air passage between the vane and housing as
the vane moves in a direction to open the damper,
permit air flow through the housing past said
vane, the vane and housing' being formed and
a predetermined clearance in said housing so as to
disposed relative to one another so as to increase
the size of the air passage between the'vane and
10 osoillate with one of the aforesaid oscillatory housing as the Vane moves in a direction to open
damper and vane, and adjustable means for per- ` the damper, and adjustable means on the hous
mitting discharge .of air to the atmosphere from ing for regulating the flow oi’ air past the vane. _
a counterweight _carried on anarm arranged to
said housing from behind the vane therein.
'
I3. A stoker air control comprising a damper
15 mounted within an air conduit for delivering
air under pressure to a stoker retort, said damper
having oscillatory movement from a position clos
6. A draft regulator comprising a damper
mounted within a conduit for oscillatory move
ment from a. position closing the opening there 15
through to another position substantially Opening
ing the opening therethrough to another posi
said conduit, al segmental-shaped housing com
municating with said conduit adjacent the damp
tion substantially opening said conduit, a seg
er, a vane mounted for oscillatory movement in
20 mental-shaped housing communicating with said
conduit adjacent the damper, a gravitating vane
mounted for oscillatory movement in said hous-l
ing on an axis eccentric with respect tothe arcu
ate wall of said housing and operatively connected
said housing and operatively connected with said 20
damper, said vane being movable with a prede
termined clearance in said housing so as to per
mit air flow through the housing past said vane,
the vane and housing being formed and disposed
with said damper so as to close the damper when
the vane is in lowermost position, said vane be
relative to one another so as to increase the size
ing operable with a. predetermined clearance in
. said housing variable due to the eccentric mount-
as the vane moves in a direction to open the
damper, a counterweight carried on an arm ar
ing of the vane to permit air ñow from the con
ranged to osciilate with one of the aforesaid os
duit into the housing and past said vane. whereby
cillatory damper and vane, and adjustable means 30
on the housing for regulating the flow. of air past
said vane is adapted to be raised by increased
pressure in said conduit to open said damper and
lowered upon a decrease in pressure to close said
damper, the clearance between the vane and
housing increasing as Ithe vane moves in a. direc
tion to open the damper, a counterweight on an
arm oscillating with one of the aforesaid damper
and vane so as to give increased counterbalanc
ing effect with increased opening of the damper,
40 and adjustable means for permitting discharge of
air to the atmosphere from said housing from be
hind the vane therein.
4. A Stoker air control comprising a damper
mounted within an air» conduit for delivering air
45 under pressure to a stoker retort, said damper
having oscillatory movement from a position clos
ing t-he opening therethrough to another posi
tion substantially opening said conduit, a segmen
tal-shaped housing communicating with'said con
5o duit adjacent the damper, a gravitating vane
mounted for oscillatory movement in said hous
ing on an axis eccentric with respect to the arcu
ate wall of said housing and operatively con- ,
nected with said damper so as to close the damper
55 when the vane is in lowermost position, said vane
of the air passage between the vane and housing
the vane.
7. A draft- regulator comprising a damper y
mounted within a conduit for oscillatory move
ment from a position closing the opening there
through to another position substantially open
ing said conduit, a segmental-shaped housing
communicating with said conduit adjacent the
damper, a vane mounted for oscillatory movement
in said housing on an axis eccentric with respect
to the arcuate wall thereof and operatively oon
nected with said damper, said vane being movable
with a predetermined clearance inl said housing
so as to permit air now throughthe housing past
said vane, the clearance betweenthe vane and 45
housing increasing as the vane moves in a direc
tion to open the damper, and adjustable means
on the housing for regulating the ñow of air past
the vane.
8. A draft regulator comprising a damper 50
mounted within a. conduit for oscillatory move
men-t from a position closing the opening'there
through to another position substantially opening
said conduit. a segmental-shaped' housing com
municating with said conduit adjacent the damp 55'
being operable with a predetermined clearance in
said housing variable due'to the eccentric mount
er, a vane mounted for oscillatory movement
in said housing on an axis eccentric with respect
ing of the vane to permit air flow from the con
and lowered upon a decrease in pressure to close
to the arcuate wa'll thereof and operatively con
nected with said damper, said vane being mov
able with a predetermined clearance in said hous 60
ing so as _to permit air flow through the hous
ing past said vane, the clearance between the
said damper, the clearance between the vane and
vane and housing increasing as the vane moves
housing increasing as the vane moves in a direc
in 'a direction to open the damper, a counter- ,
duit into the housing and past said vane, where
0 by said vane is adapted to be raised by increased
pressure in said conduit to open said damper
65 tion to open the damper, and adjustable means
for permitting discharge of air'to the atmosphere
from said housing from behind the vane therein.
5. A draft regulator comprising a damper
mounted wit-hin a conduit for oscillatory move
o ment' from a position closing the opening there
through to another position substantially open
ing said conduit, a segmental-'shaped housing
Weight on an arm oscillating with one of the 65
aforesaid damper and vane so as to give increased
counterbalancing effect with increased opening
of the damper, and adjustable means on the
housing »for regulating the ñow of air past the
vane.
FLOYD R. NELSON.
70