Dampers for Steam Boiler and other Fire Places.
Year: 1888

page_text: Dampers for Steam Boiler and other Fire Places.
I, AXEL VALDEMAR BAY of Nakskov, Denmark, Proprietor of a Steam Flour Mill
do hereby declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
It is well known that the dampers for regulating the draught in fire places should
be opened much wider just after a fresh charge of fuel than later on, when the fuel
thrown in has become first heated then ignited and then in full glow. By means of
the adjustable regulators hereinafter to be described the dampers will just after the
fresh charge of fuel begin to close gradually and automatically at about the rate
required for proper firing. By the adjustability of the regulators the limits for the
position of the damper can at will and readily be varied while its speed of motion
from the highest to the lowest limit is retained. The dampers may be closed either by
means of a falling weight, of which the damper besides various movable parts of the
regulator may form a part, or by means of gas pressure water pressure or steam
pressure. The motion thus produced can be retarded or suitably slowed down by
means of a pneumatic, hydraulic or steam brake.
As shewn in the vertical section Figure 1 the damper may be closed by a falling
weight alone. The regulator in this case consists of a cylinder 6 fixed against a wall a
and provided with a well fitting piston c and piston rod d, and with a suction valve f;
also with a cock in the upper cylinder end but not shewn in the drawing, while the
lower cylinder end has holes to the atmosphere. The piston rod d is connected to a
frame 9 the side limbs of which pass through eyes or other guides on the cylinder
such for instance as shewn. To the frame is attached a chain h which passes over
pulleys and down to the ash pan damper or door which is supposed to be of a flap or
other form so that it will close by its own weight. Weights may according to
circumstances be attached to the chain ends, as for instance here shewn at for the
purpose of giving the damper with its attached chain end a suitable overbalancing
power.

page_text: Just after the firing the stoker opens the damper for instance by depressing with
his foot the stirrup i so as to pull down the piston c into the position shewn while the
air flows into the space above the piston through the suction valve f. When the
stoker then lets go the stirrup i, the damper will by its own weight or more or less
assisted or counteracted by the aforesaid weights on the chain strive to draw the
piston c upwards, but the escape of the air above the piston being retarded by the
suitable partial closing of the aforesaid cock in the upper end of the cylinder
the ascending movement of the piston will be retarded as required.
There are a number of holes in one limb of the frame g and by inserting pegs
which abut against the ends of the frame guide on the cylinder the movement of the
piston will be limited and thus also that of the damper.
If as shewn in Figure 2 the ashpan damper j is flapshaped its movements may be
limited by pegs inserted in holes in the two wings of a sector m between which works
the sweep & that is fixed on the spindle n of the damper. The chain is attached to
and passes over the sweep k, so that the leverage remains the same in all positions.
Instead of in Figure 1 to let air be the counteracting medium in the ascent of the
piston I may employ a liquid or steam. If a liquid is used I of course let the valve
and the cock terminate in a suitable liquid reservoir instead of leading into the open
air. If I use steam I find it most convenient to exchange the suction valve for a
steam cock for admitting steam above the piston when the damper is to be opened and
the piston e depressed, this cock being shut when the piston has come to the bottom
of the cylinder, or so far down as the aforesaid stopping pegs will admit. Instead of
steam pressure I can of course similarly use gas pressure or liquid pressure for
depressing the piston and opening the damper. It should further be noted that the
whole cylinder can be turned upside down, so that the chain h leads directly to the
damper instead of first passing over pulleys.
b
Where the damper is closed by a falling weight the retardation in the act of closing
can be effected by a suction in the cylinder instead of by a pressure therein as stated.
In the arrangement Figure 1 I replace the cock and the suction valve in the upper
cylinder cover by a cock and a pressure valve in the lower cylinder cover, which is
.otherwise made to close tightly while the upper cylinder cover is perforated. When
the piston c is drawn down the air or liquid below the piston will be driven out
through the pressure valve, and the next following raising of the piston will be
counteracted and retarded by the limited admission of air or liquid by the bottom
cock to the space below the piston.
Figure 6 shews an example of combined pressure and suction for retarding the
closing of the damper. The cylinder a is closed at both ends. In the opening of
the damper the piston c is pushed downwards and the air or liquid then finds an easy
passage from one side of the piston to the other through the valve therein. But in
the ascent of the piston when the damper is closing the air or liquid above the piston
must pass through the pipe in order to enter the space below it, and this passage is
hindered as desired by the screw spindle valve 1. By means of a very fine hole in the
side of the pipe the difference in volume of air or liquid which the cylinder can take
according as the piston rod is drawn more or less out of the cylinder or pushed in
more or less is made up for. If a liquid is used the cylinder can be used as a reservoir,
or the fine hole terminates in a reservoir for receiving the liquid pressed out of the
cylinder by the depression of the piston. And when the retardation is caused by
suction alone or pressure alone ihe valve can be arranged in the piston as in
Figure 6.
2
Figure 3 is a section through a regulator in which the damper is closed by the
pressure of steam, gas or liquid, while the motion is retarded by a resistance from
liquid, air or steam in the cylinder, the exit taking place only through a fine hole, the
size of which can be regulated at will by the plug of a cock. On the piston rod d is
keyed a cross head g which connects it with a shifting rod g₁, provided with adjustable
tappets, for the opening and closing of the cock i, on the pipe i, which latter admits
steam or liquid pressure above the piston for closing the damper. The closing is also
furthered by the weight of the piston, the piston rod, the shifting rod g and the

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weights which may be put on the piston rod. The rod g and the cross-head
connected by a pinching screw in order that the two tappets ₁ may be adjusted
simultaneously when their right distance has been determined. One of the tappets i
opens the cock i, when the piston comes to its highest position, and the other closes
the cock when the piston comes to its lowest position. The air steam or liquid in the
upper part of the cylinder must of course have an outlet by a suitable cock (not
shewn in the drawing) when the piston has reached its lowest position before it rises
again. The tappet, which closes the cock i may also automatically open the first
named cock.
Instead of the chain connection as in Figure 1 I may so connect the piston rod d
with the damper, that opening it directly effects the motion of the piston either upward
or in Figure 3 or laterally if the damper, is in the form of a sliding door and the
cylinder therefore suitably is placed horizontally instead of vertically.
Figure 4 shews an example of a flap damper as for the fire place of a steam boiler:
The damper has a hook for turning it by; k is a tooth sector fixed on its prolonged
axis and kept in gear with a tooth rack by means of the rollers s in a flap which is
held in place by a flap p. The rack his jointed to the end of the piston rod d. In
the parts p and q are formed slots for the rack to be guided sideways therein but so
that the flap p can be raised and thus take the rack out of gear with the sector k,
which latter works between fixed sweeps or cheeks m with holes through for stop pegs
for limiting the motion of the sector as in Figure 2.
If in the arrangement Figure 3 liquid is used for retarding the descent of the
piston, the open reservoir y in one with the cylinder is charged with the liquid, which
in the ascent of the piston runs from y through the suction valve fin below the piston,
returning to it in the descent of the piston through the pipe which is provided with
a suitable cock for regulating the outflow from the cylinder. If air be used for
retarding the descent of the piston, the reservoir y is left empty. If steam is used for
the retardation the suction valve f is not needed but instead of that I use a cock on a
steam admission pipe whereby steam is let into the cylinder below the piston, thus
raising the latter and opening the damper. Or instead of steam pressure I may
similarly use air pressure or liquid pressure for raising the piston.
The aforesaid suction valve or pressure valve may always be replaced by a cock
which is opened or closed as required, and this cock may even be the same as the one
whereby the outflow from the cylinder during the descent of the piston is limited and
regulated. Figure 5 shews this applied as an example of a regulator used in connection
with rotary dampers such as are generally used on the doors of magazine stoves or
slow combustion stoves. a is such a door with its hinge lugs and handle knob. jj are
the two screw dampers on the door. . For each damper the door forms a cylinder
with stuffing box and plunger c. On the top of each plunger there is a cross bar d
with tooth rack passing down by the side of its damper gearing with a tooth wheel k
thereon so that it opens and shuts by the motion of the piston c in its cylinder. 1 is
a passage leading from the bottom of cylinder and having a cock for regulating the
flow according to circumstances. Just after firing one or both plungers are pulled up
(according to which damper one wishes to open) by means of the cross pieces d or by
handles thereon, after that the corresponding cock or cocks have been opened for
freely admitting air during the ascent of the plunger or plungers. When the latter
have been raised into the desired position, the cocks are so set that the air outlet
under the plungers is limited as desired. To facilitate this an index hand may be put
on each cock for indicating on a suitably graduated scale. The plungers will then by
their own weight (which can be regulated by putting shot into a hollow provided in
them) descend gradually as the air below them can escape through the passages and
thus gradually close the dampers j. While the plungers stand in their lowest position
they may be brought out of action by turning them round on their axis thus dis-
engaging the racks from the pinions k on the dampers; these latter may then be set
by hand according to the minimal opening desired, whereupon the tooth racks can be
turned into gear again. By insertion of suitable stop pegs for instance into the sides

page_text: of the cylinders the tooth racks are prevented from getting accidentally out of gear
with the pinions.
In all the forms of damper regulator I can employ electrical signalling appliances
for indicating when the damper has reached its minimal opening. I have not specially
described them as they may be greatly varied, but their working will always mainly
depend upon the application of a contact at the terminal position of the damper or the
piston or plunger, so that thereby an electric circuit is closed and an electric signalling
appliance is set going. Such signalling apparatus is of special and great value for
large fire places such as for steam boiler, where the stoker is thus advised whenever
firing is required.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is :
First Fireplace damper regulators constructed substantially as described in which
the damper after a fresh charge of fuel has been put on is gradually closed by means
of a descending weight retarded as required by air, steam or liquid enclosed in a
cylinder above or below a piston which is moved by the said weight, so that the said
enclosed fluid can only adequately slowly escape by an adjustable cock, while the
movement of the piston in the opposite direction and consequent raising of the weight
and opening of the damper is effected either by man's power, or by the pressure of air,
steam or liquid caused to act on the required side of the piston.
Second The application in damper regulators constructed substantially as firstly
claimed of suction either alone or in conjunction with pressure for retarding the
motion of the piston which closes the damper, the piston, either instead of or besides
pressing an enclosed quantity of steam, air or liquid out through a fine opening,
being made to draw in air or liquid through a sufficiently fine opening on its opposite
side.
Third The application in damper regulators constructed substantially as firstly
claimed of air, steam or liquid pressure alone instead of the said descending weight or
in conjunction therewith for causing that motion of the piston whereby the damper is
closed, and that whether the retardation of the motion be effected by an enclosed
quantity of air, steam or liquid to be pressed out of a sufficiently fine opening, and
irrespective of the means employed for moving the piston in the opposite direction.
Fourth-The application in damper regulators as herein before claimed of electrical
signalling appliances for indicating the terminal positions of damper or piston
substantially as set forth.
Fifth The constructions of fireplace damper regulators shewn on the drawings.
Dat this and
L1000