U.S. patent number RE31,256 [Application Number 06/357,833] was granted by the patent office on 1983-05-31 for automatic damper means and controls therefor.
Invention is credited to Robert H. Schmidt.
United States Patent |
RE31,256 |
Schmidt |
May 31, 1983 |
Automatic damper means and controls therefor
Abstract
An automatic damper means and controls, which provide an
exceedingly safe automatic damper for the exhaust duct-work of an
associated gas furnace or the like, by automatic control of the
damper, and automatic control of the gas supply, with redundancy
features for providing exceedingly safe operation.
Inventors: |
Schmidt; Robert H.
(Indianapolis, IN) |
Family
ID: |
26999812 |
Appl.
No.: |
06/357,833 |
Filed: |
March 12, 1982 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
870479 |
Jan 18, 1978 |
04254759 |
Mar 10, 1981 |
|
|
Current U.S.
Class: |
126/307A;
110/163; 126/285B; 236/1G; 431/20; 431/80 |
Current CPC
Class: |
F23N
3/085 (20130101); F23L 11/005 (20130101); F23N
2235/10 (20200101); F23N 2235/04 (20200101) |
Current International
Class: |
F23N
3/00 (20060101); F23L 11/00 (20060101); F23N
3/08 (20060101); F23J 011/00 (); F23L 001/00 ();
F23N 005/10 () |
Field of
Search: |
;126/285R,285B,37A
;236/1A,1G ;431/20,18,78,79,80 ;110/163 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Connor; Daniel J.
Attorney, Agent or Firm: Spray; Robert A.
Claims
What is claimed is:
1. Damper control means for a damper means of a flue duct, which is
provided with support means which support the damper means in the
associated duct-work in and between a duct-open and a duct-closing
position, comprising, in combination:
crank means operatively connected to the support means;
link means for rotating the crank means;
movable first control means for moving the link means to rotate the
crank means;
drive means for moving the movable control means for rotating the
crank means; and
actuation control means for actuating the said drive means, and
operative in response to an associated thermostat means and to the
previous movement of the drive means to actuate the drive means so
as to cause and permit only movement thereof sufficient to rotate
the crank means between the duct-closing and duct-open positions of
the damper means.
2. The invention as set forth in claim 1 in a combination in which
the said control means not only moves the link means but also
controls the said actuation control means to achieve its
operativity as stated.
3. The invention as set forth in claim 1 in a combination in which
there are provided a pair of switch means in the actuation control
means, one of which is operative to energize the drive means
between the stated limits and the other of which is operative to
permit energization of the drive means for a subsequent cycle even
though the first has been caused by a previous cycle to be in
non-energizing setting as the energizing the drive means.
4. The invention as set forth in claim 3 in a combination in which
there is also provided a switch means which controls fuel supply to
the associated heat means whose combustion products are vented by
the flue duct, and the said control means comprises a cam member
having a first portion which is operative to control the first of
said switch means, and a second portion which is operative to
control the switch means which controls the fuel supply.
5. The invention as set forth in claim 4 in a combination in which
the said second portion of the control means also is supportingly
connected to the said link means for providing the controlled
movement thereof which rotates the crank means and thereby also the
damper means.
6. The invention as set forth in claim 4 in which the said first
portion of the control means cam member is provided as a curved cam
component, and the said second portion of the control means cam
member is provided as a pin means.
7. The invention as set forth in claim 5 in which the said first
portion of the control means cam member is provided as a curved cam
component, and the said second portion of the control means cam
member is provided as a pin means.
8. An automatic damper means for an associated gas furnace or the
like, having damper control means according to claim 1, the
automatic damper means also including a damper means and a control
means both provided on a section of duct which is adapted to be
installed as a unit into the exhaust duct-work of the associated
furnace or the like, and in which the damper means includes a
damper plate means having at least two relatively large components
which are movable relative to one another.
9. A damper for a duct of a gas furnace or the like, having a
damper control means according to claim 1, in which the damper
includes a plate means which in duct-closing position extends
generally transverse to the duct for blocking exhaust flow through
the duct, the improvement which comprises providing the plate means
in at least two parts, and providing that in their most fully
duct-closing position there it still a significant area not blocked
thereby, the non-blocked are a being large enough to permit gas
leakage to draft upwardly.
10. The invention as set forth in claim 9 in which there are two
plate means, they being supported in a slightly spaced manner such
that in most duct-closed position the spacing therebetween provides
the said gas-leakage area.
11. A damper means for the flue gas duct of a gas furnace or the
like, according to claim 1, in which the damper means is provided
to be a plate means comprising at least two parts which are
relatively movable with respect to one another, there being support
means and control means which supportingly position the parts of
the damper plate means in and between duct-open or duct-closed
position.
12. A damper means for the flue gas duct of a gas furnace or the
like, according to claim 1, in which control means are provided as
to the fuel supply which are responsive to heat build-up in the
draft diverter of the associated furnace or the like, the sensing
component or components of the control means being located in the
region of the draft diverter.
13. A damper means for the flue gas duct of a gas furnace or the
like, as set forth in claim 12, in which the heat-responsive
control means, which sense heat-buildup in the draft diverter, also
are operative, upon sensing such heat-buildup in the draft
diverter, to de-energize the actuation means of the damper.
14. Damper control means for a damper means of a flue duct, which
is provided with support means which support the damper means in
the associated duct-work in and between a duct-open and a
duct-closing position, comprising:
crank means operatively connected to the support means;
link means for rotating the crank means;
movable first control means for moving the link means to rotate the
crank means;
drive means for moving the movable control means for rotating the
crank means;
actuation control means for actuating the said drive means, and
operative in response to an associated thermostat means and to the
previous movement of the drive means to actuate the drive means so
as to cause and permit only movement thereof sufficient to rotate
the crank means between the duct-closing and duct-open positions of
the damper means;
and in which there are provided a pair of switch means in the
actuation control means, one of which is operative to energize the
drive means between the stated limits and the other of which is
operative to permit energization of the drive means for a
subsequent cycle even though the first has been caused by a
previous cycle to be in non-energizing setting as to energizing the
drive means;
in a combination in which a first portion of the control means
controls one of the said switch means and a second portion of the
control means is a pin means which controls the second of the
switch means and also is supportingly connected to the said link
means for providing the controlled movement thereof which rotates
the crank means and thereby also the damper means.
15. A damper control means for a gas furnace or the like in which
heat-sensitive means are provided in the draft diverter opening
component of the associated furnace, and is operative, in response
to heat build-up therein caused by any blockage of the exhaust
stack above the draft diverter component, which heat build-up
causes spillage of hot flue gases out of the opening of the draft
diverter hood, to close the associated energy-supply to the said
furnace or the like, the heat-sensitive means being of a type which
achieves that energy-supply closing in response to an increase of
heat at the location of the said draft diverter opening;
in which the said heat-sensitive means includes a pair of
heat-sensitive components, each of which is operative in response
to heat build-up in the draft diverter to close the associated
energy-supply to the said furnace or the like; and one of the
heat-responsive components is in a thermocouple circuit independent
of line voltage, thereby providing special safety means for
achieving energy-supply shutoff not only independently of line
voltage but also in circuitry which is non-electrically resettable,
avoiding thereby any cycling or flutter of the control thereby
achieved for the energy-supply means by the heat-responsive
component of the thermocouple circuit, and also thereby avoiding
any possibility of continuation of exhaust gas spillage out the
draft diverter once the thermocouple circuit's heat-responsive
component has achieved energy-supply shutoff even momentarily.
.Iadd. 16. A damper control means for a gas furnace or the like in
which heat-sensitive means are provided in the draft diverter
opening component of the associated furnace, and is operative, in
response to heat build-up therein caused by any blockage of the
exhaust stack above the draft diverter component, which heat
build-up causes spillage of hot flue gases out of the opening of
the draft diverter hood, to close the associated energy-supply to
the said furnace or the like, the heat-sensitive means being of a
type which ahcieves that energy-supply closing in response to an
increase of heat at the location of the said draft diverter
opening;
in which the said heat-sensitive means includes a heat-sensitive
component which is operative in response to heat build-up in the
draft diverter to close the associated energy-supply to the said
furnace or the like; and the heat-responsive component is in a
thermocouple circuit independent of line voltage, thereby providing
special safety means for achieving energy-supply shutoff not only
independently of line voltage but also in circuitry which is
non-electrically resettable, avoiding thereby any cycling or
flutter of the control thereby achieved for the energy-supply means
by the heat-responsive component of the thermocouple circuit, and
also thereby avoiding any possibility of continuation of exhaust
gas spillage out the draft diverter once the thermocouple circuit's
heat-responsive component has achieved energy-supply shutoff even
momentarily. .Iaddend.
Description
The present invention relates to an automatic damper means, such as
for gas furnaces, and to control means therefor; and concepts
provide exceeding high safety, with ample redundancy as to the
control of the combustion gas, and with automatic control of the
actuation and setting of the damper as to assure safety.
It has been long known that many installations such as gas furnaces
and the like, utilizing the combustion of fuels, would be more
effective if an amply-safe means could be provided for
automatically controlling the flue or exhaust ducts thereof so as
to cause the exhaust duct-work to be closed during idle periods of
the equipment yet automatically open if the equipment was in its
combustion mode or operation.
Obviously, the products of combustion of fuel are or can often be
very dangerous and even fatal to human beings if not safely
exhausted; and thus the lack of an effective and fool-proof
automatic damper control has long meant that no automatic damper
means has been permitted to be used.
Obviously, also, much heat has been wasted, by exhaust flues being
always open, as is generally considered to be necessary for most
persons would forget to open any closed damper prior to utilizing a
furnace or heater; and thus no heat-saving dampers are provided for
such equipment. Even as to fireplace installations which do have
dampers, many homeowners leave them always open, once they have
experienced an accident of leaving them closed during
operation.
Accordingly, the present concepts of a reliable and amply safe
automatic damper, with features of redundancy as to safety factors,
provide a very advantageous installation achieving a tremendous
savings in heat energy presently wasted, yet providing high safety
nevertheless.
Further, the concepts provide that the damper unit may be
relatively easily installed, as a unit, which contains the damper
and the controls therefor, and, further, the concepts provide extra
safety by heat-sensitive components easily mounted to components,
such as the draft diverter, which are generally easy and convenient
to reach, and .[.which provide a component.]. which provide a
component which readily can indicate any heat build-up which would
be an indication of any flue blockage or malfunction of the flue or
the damper means.
The accompanying drawings illustrate the concepts:
FIG. 1 is an elevational view, partly in section, and with portions
broken away for clarity, of the damper control mechanism mounted on
a duct-section which would be installed as a unit into the exhaust
duct of the associated furnace or the like;
FIG. 2 is an elevational view of the parts shown in FIG. 1, taken
generally as indicated by view-line 2--2 of FIG. 1, portions shown
as removed or broken away for clarity, and to avoid obscuring of
details otherwise hidden;
FIG. 3 is a diagrammatic view of the damper-control mechanism of
FIGS. 1 and 2, but illustrating only certain portions thereof, this
view illustrating the damper in duct-closed position, and taken
generally as indicated by view-line X--X of FIG. 1;
FIG. 4 is a view similar to FIG. 3, but illustrating the duct in an
open position, and taken generally as indicated by view-line X--X
of FIG. 1;
FIG. 5 is a pictorial representation of a control cam component
illustrated in the preceding views;
FIG. 6 is a pictorial representation of a furnace or the like,
having the damper control mechanism and duct unit of FIGS. 1 and 2
installed in the unit's duct-work, and illustrating control means
also installed in the unit's draft diverter;
FIG. 7 is a view similar to FIG. 6, illustrating both the damper
components and the control means as installed onto a furnace or the
like, but of configuration different from that of FIG. 6;
FIG. 8 is a pictorial representation of the damper and damper
control means, mounted on a unit of duct-work as indicated in FIGS.
1 and 2, but on a smaller scale;
FIG. 9 is a pictorial representation of the control means which is
shown in FIGS. 6 and 7 as mounted on the draft diverter, and
FIG. 10 is a schematic representation of both the damper control
means and the heat-sensitive control means which is mounted in the
draft diverter of the associated furnace or the like.
(It will be understood that the drawings are to a certain extent
schematic, for illustrating the concepts.)
As stated above, the invention provides controlled damper means for
a gas furnace or the like, which provides the advantage of
fuel-saving economy of an automatically movable damper but
nevertheless also provides safety in the form of a fully complete
shutdown of the related appliance in the event of a burner
malfunction, or flue restriction or damper failure.
The drawings illustrate details of the inventive concepts. As there
shown, the most obvious general components or sub-assemblies are
the damper 10 (FIGS. 2, 3, 4, and 8), damper-movement control 12
which is mounted on the side of a damper housing 14, and auxiliary
safety control 16 mounted in the draft diverter 18 of the furnace's
exhaust duct 20.
As illustrated in this embodiment, the damper 10 and the
damper-movement controls 12 are provided in a pre-assembled manner
on a damper housing 14 which is shown as a short duct section which
the user will insert into the furnace's exhaust duct 20.
Each of these general components or sub-assemblies (10, 12, and 16)
are now more fully described, in conjunction with their use in this
advantageous invention.
The damper assembly 10 is shown as of two-part nature. That is, the
damper 10 as shown is provided to have two semi-circular plates 19
which are movably supported (as detailed below) centrally of the
damper housing 14 of exhaust duct 20, along a diameter thereof.
It will be noted that the damper assembly 10 is formed such that
between the damper-plates 19 there is a space 22 (FIGS. 3,4)
extending diametrically of duct-section 14, at the juncture of the
two damper-plates 19. That slot or opening 22 is large enough to
allow proper operations of damper plates 19 and to permit any gas
leakage to draft upwardly out of exhaust duct 20, even when the
damper plates 19 are in closed position as shown in FIG. 3.
Control 12 for damper 10, for damper-opening:
The damper control 12 will now be described in conjunction with its
illustrative showing in the drawings. As shown in FIGS. 1,2,3,4 and
10, its most obvious components are relay 30, a pair of
microswitches 32 and 34, and a motor 36 having a gear reduction
feature. FIG. 10 shows the circuitry, now described, power being
supplied at 37.
Operation of the damper control unit 12, for damper-opening, is as
follows: When the associated thermostat 38 of the furnace control
calls for heat, it being assumed that the damper plates 19 have
been at that time in closed position, the relay 30 is energized
through energization of relay circuit 40. This energization of
relay 30 in turn moves to switch to closed position one switch
blade 42 of the relay's normally-open switch contacts in the
portion 44 of the motor circuit 46. This energizes the drive motor
36; and the motor 36 begins to turn, that motor movement causing an
actuator cam 48 (FIGS. 1, 2, 3, 4, 5, and 10) to revolve
180.degree..
At this point, the damper plates 19 have moved 90.degree. to open
position, due to that movement of the drive motor 36, as explained
more particularly hereinafter.
This movement of the actuator cam 48 driven by motor 36 activates
the two microswitches 32 and 34, as explained more particularly
below, the microswitch 32 then turning off the drive motor 36 by
its switch blade 50 moving to an open position in which it opens
the motor-circuit 44 which through switch blade 42 had energized
the switch contact from which the switch blade 50 left as caused by
that 180.degree. movement of cam 48.
That movement of cam 48 also, in its movement which corresponds to
the last 4.degree. of opening of the damper plates 19, causes the
normally-open blade 52 of the microswitch 34 to move to
switch-closed position, closing circuit 54 to thereby energize the
gas valve solenoid 56 of gas valve 57 of gas line 58 for the
furnace, firing the furnace; but, as mentioned above, the damper
plates 19 of damper 10 have moved to the duct-open position.
Control 12 for damper 10, for damper-closing:
When the temperature-need has been satisfied, the thermostat 38
opens the relay circuit 40, moving switch blade 42 of relay 30 back
off (leftwardly in FIG. 10) from the contact which had energized
the motor 36 through motor circuit-portion 44 and the other switch
blade 50 prior to that switch blade 50 having moved to its other
position; but this change of switch blade 42 (to the left in FIG.
10) again now energizes the motor 36 due to the other switch blade
50 now being in circuit-closing (leftward, FIG. 10) position now in
series with switch blade 42, again energizing the motor 36 through
motor-circuit 44.
The motor 36 then begins its movement of another 180.degree.; and
this causes the microswitch 32 to again change due to actuation of
cam 48, and this moves switch blade 50 to a position (rightward,
FIG. 10) again out of series with switch blade 42 and thus again
de-energizing the motor 36 by de-energizing or opening the
motor-circuit portion 44.
(The motor 36 is now back at the beginning of its cycle described,
awaiting energization through circuit portion 44 the next time the
closing of the thermostat 38 in a heat-needing situation energizes
relay circuit 40 to actuate the relay 30.)
Similarly to the actuation during damper-opening, and as explained
further below, this movement of motor 36 and its actuator cam 48
also causes switch blade 52 of microswitch 34 to move to
open-circuit position, de-energizing the gas valve solenoid 56 of
gas valve 57, in the first 4.degree. of damper-closing actuation of
damper plates 19 as caused by this movement of drive motor 36.
Auxiliary Safety Controls 16:
The advantageous safety control 16 as shown comprises a pair of
thermal discs 60 and 61. These thermal discs 60 and 61 are devices
which have a switch 62 which is normally closed but which opens in
response to heat.
The circuitry in which the thermal discs 60 and 61 are contained is
shown as now described, as shown in FIG. 10.
One of the thermal discs 60 is in the circuit 54 and therein in
series with the magnetic solenoid 56 of gas valve 57 which is
actuated by closure of the thermostat 38 when heat is needed,
although that thermal disc 60 is located in the auxiliary safety
control box 16. Heat energization of the thermal disc 60 opens its
switch 62, opening electric control circuit 54 and thus closing gas
valve 57.
The other thermal disc 61 is in a circuit 63 in series with the
thermocouple 63a which activates another gas valve 64, that valve
64 being in series with the gas valve 57 which is controlled by the
controlled gas valve solenoid 56 mentioned above. The operativity
of control circuit 63 is such that the gas valve 64 is open if
there is no heat-energization of the thermal disc 61 in control
circuit 63 by a heat build-up in the draft diverter 18, which opens
switch 62 and thus circuit 63, closing gas valve 64.
It is to be noted that the two gas valves 57 and 64, being in
series, achieve a double positiveness of safety control, for each
is controlled by one of the heat-responsive current-stopping
thermal discs 60 and 61. Thus the two thermal discs 60 and 61
provide double positiveness of safety; for the heat-actuated
opening of the respective circuit through either one thermal discs
60 or 61 would itself act to close (or permit closure, depending
upon the bias of gas valve controls used) one of the two gas valves
57 and 64 in the series arrangement noted.
More particularly, as to the two thermal discs 60 and 61, these are
located in the safety control unit 16 which is mounted in the draft
diverter component l8 of the furnace ductwork 14 (FIGS. 6 and
7).
This positioning of the safety control unit 16, which contains the
two heat-responsive thermal discs 60 and 61, provides great safety;
for, when there occurs any heat build-up in the furnace's exhaust
ductwork 20 for whatever reason (clogging of the flue or even
anything which would cause the damper 10 to remain in duct-closed
position even though both the gas valves 57 and 64 were open), that
heat will cause both thermal discs 60 and 61 to open their circuits
(respectively 54 and 63) each itself sufficient to prevent gas-flow
through the gas line 58, by closing gas valves 57 and 64,
respectively.
(The operation assumes that the high limit switch 65, which is a
component of the furnace and is in series with the gas valve
control 56 in circuit 54, is closed.)
The control 16 has an upturned flange 66, with holes 67 for screws
68 to fasten the unit 16 to the draft diverter 18.
Mechanism details of damper control 12:
The damper control 12, as shown, has been described above generally
in its functional aspects; and now it is described in respect to
the structural details and concepts which provide those operational
functions.
Accordingly, the structural details of the damper control 12 are
best shown in FIGS. 1 through 5, and 8.
The mounting of damper control 12 is shown in FIGS. 1 and 2 (the
cover plate 69 of control unit 12 being omitted for clarity in FIG.
2) as by screws 70 extending through a rear wall 72 of control unit
12 into mounting brackets 74 shown welded as at 76 to the
duct-section 14.
(That duct-section 14 is the section or duct-component (FIG. 8)
which is inserted into the ductwork 20.)
The damper half-plates 19 of damper 10 are shown as each mounted
(in the duct-section 14) on a horizontal rod 78 which extends
diametrically through the duct-section 14, that mounting being
shown as being at a location where the side-wall 77 of duct-section
14 is provided with an internal bead or flange 79,
cross-sectionally of a V-shape or U-shape, which provides the
double advantage of a stiffening rim and a wall 80 onto which the
damper plates 19 of damper 10 seat.
The rods 78 pass through the wall 77 of duct-section 14 by passing
through holes 82 in the duct-wall 77 in line with the bead or
flange 79, those holes 82 being small enough in relation to the
size of the rods 78 to provide support thereof although permitting
the rotatability of rods 78.
There are mounting holes 84 in the opposite side wall portion 77 of
duct-section 14, opposite those holes 82 indicated in FIGS. 1 and
2; and the corresponding spacing of holes 82 on one side, and of
holes 84 on the other side, provides the spacing 22 (FIGS. 3 and 4)
already mentioned.
The mounting of damper half-plates 19 of damper 10 onto the support
rods 78 is shown as by welding 86, which provides that the plates
19 are fixed relative to the rods 78; and thus the controlled
rotation of support rods 78 is operative to correspondingly control
the movement of damper plates 19 in and between their duct-closing
(FIG. 3) position, and the duct-open (FIG. 4) position.
The illustrated controlled rotation of support rods 78 is now
described.
As shown in FIGS. 1 through 4, the end-portion of rods 78 adjacent
the control unit 12 is shown as integrally bent transversely to
provide a crank-arm 88 having an axially-bent end finger 90 which
provides a crank member for the rods 78.
These crank-fingers 90 of rods 78 are shown at respectively
received in holes 92 of control links 94, the ends thereof opposite
the holes 92 having holes 96 which rotatively receive a pin 98
fixed to the cam member 48 mentioned above; and, as more
particularly described herein, it is the cam member 48 which both
controls actuation of micro-switch control blades 50-52, and
controls rotation of rods 78 through crank-fingers 90.
Further details of the cam member 48, as shown, are now set forth;
and these may be probably most easily understood by considering
FIGS. 1,2, and 5, along with the sequential representation shown in
FIGS. 3 and 4.
The cam member 48 is shown as carried on a shaft 100, affixed
thereto as by set screw 102, the shaft 100 being driven by suitable
gearing or other drive means from the motor 36.
The cam member 48 is shown as having a pair of arms 104 and 106, as
shown, these being shown as extending generally radially from the
shaft 100 at a spacing therearound of 90.degree. as shown. The
cam-arm 106 is shown as provided with a hole 107; and it is through
this hole 107, in the embodiment shown, through which is fastened
the aforesaid pin 98, the movement of the cam member 48 thus being
effective through its arm 106 and the pin 98 to move the control
links 94. That is, noting the differences between FIGS. 3 and 4,
the movement of cam member 48 (counterclockwise as shown in FIGS. 3
and 4) swings the pin 98 in a counterclockwise direction, between
the positions shown in FIGS. 3 and 4; and, since the cam-pin 98 is
received in holes 96 of the control links 94, the counterclockwise
travel of cam-pin 98 is operative through the links 94 to rotate
damper-support rods 78 in rotational directions, one rod 78
rotating clockwise and the other rod 78 rotating counterclockwise
in their respective movements between their position in FIG. 3 and
subsequently in FIG. 4.
Still noting particularly FIGS. 3 and 4, it will be observed that
such rotation of the damper-support rods 78 is effective to move
the damper-plates 19 carried thereon between the duct-closed
position of FIG. 3 and the duct-open position of FIG. 4, the rods
78 having travelled 90.degree. in this actuation.
Further control by the control cam 48 is as to the microswitches 32
and 34, as now described.
The electric control achieved by the control cam 48 is shown as
.[.being.]. having the cam-arm 104 bent to provide a generally
semi-cylindrical extension 108, of slightly less than 180.degree.
in extent. This curved extension 108 is shown as engageable with
the control arm 50 of microswitch 32, being effective as shown in
FIG. 3 to hold that microswitch 32 in switch-closed position in the
FIG. 3 position in which the damper 10 is in duct-closed position;
although the curved extension 108 is shown in FIG. 4 to be out of
engagement with control blade 50 of microswitch 32 in the FIG. 4
position in which the damper 10 is in duct-open position.
Further electrical control, by the cam member 48, is also achieved
by its having its pin 98 extending (leftwardly in FIG. 1) past the
location in which it receives the control links 94, sufficiently
far such that the outer (leftward in FIG. 1) end of pin 98 moves in
a path which brings it into contact with the control blade 52 of
microswitch 34. This engagement of cam-pin 98 with control blade 52
of microswitch 34 is shown in FIG. 4 as being such as to have that
control blade 52 in switch-closing position, in the FIG. 4 position
in which the damper is in duct-open position; but the cam-pin 98 is
shown in FIG. 3 as being removed from the control blade 52 of
microswitch 34 in the FIG. 3 position in which the damper 10 is in
duct-closed position.
The location of the control cam 48 is thus seen to be controlled as
shown by the motor 36. That is, the output-shaft 100 of the motor
36 is the shaft which carries the control cam 48, that mounting of
the control cam 48 being by the set screw 102 as mentioned above,
the said screw 102 passing through a threaded opening 110 (FIG. 5)
to bear upon the drive shaft 100 which has passed through an
opening 112 in an ear 114 shown as integrally formed by suitably
bending or otherwise forming the control cam 48.
Further, the location of control cam 48 with respect to the
location of its mounting shaft 100 within the control unit 12 is
also by the motor 36. That is, the motor 36 is shown as having a
frame which has support ears 116 which are held as by screws 118 to
an up-standing mounting lug or bracket 120 which extends from the
rear wall 72 of control unit 12.
The two microswitches 32 and 34 are shown as mounted, as by screws
122 which extend through the microswitches 32 and 34, and through a
intervening insulator or spacer 124, into the rear wall 72 of
control unit 12; and the mounting of those microswitches 32 and 34
is, as shown in FIG. 1, such that their respective control blades
50 and 52 are in operative alignment, respectively, with the paths
of curved cam extension 108 and the outer (leftward in FIG. 1)
portion of the cam pin 98.
Further as shown in FIG. 10, it will be noted that all the
circuitry and electrical components except the drive motor 36 and
the switch 32 are shown as provided on low-voltage side of a
step-down transformer 126, suitably reducing the voltage from power
voltage of main power circuit 37.
It is thus seen that an automatic damper means and controls
therefor, according to the present inventive concepts, provides a
desired and advantageous device and installation yielding the high
advantages of an automatic damper for exhaust ducts of a gas
furnace or the like, which is conveniently installed as a unit, and
which provides not only automaticness of operation but a high
degree of safety. Thus, when the equipment is not operating, the
damper is closed, thereby eliminating the tremendous waste of room
heat which is otherwise wasted by going up the exhaust duct or
stack; but when the equipment is operating, the damper is
automatically assured of being open. Any heat build-up in the
exhaust stack automatically shuts down the fuel supply.
Accordingly, it will thus be seen from the foregoing description of
the invention according to this illustrative embodiment, considered
with the accompanying drawings, that the present invention provides
new and useful concepts of an automatic damper and control,
yielding desired advantages and characteristics of actuation,
energy savings, and exceedingly high safety, thus accomplishing the
intended objects, including those hereinbefore pointed out and
others which are inherent in the invention.
Modifications and variations may be effected without departing from
the scope of the novel concepts of the invention; accordingly, the
invention is not limited to the specific embodiment or form or
arrangement of parts herein described or shown.
* * * * *