Note: Descriptions are shown in the official language in which they were submitted.
lZ5~0;~0~;
ZE~O CLEARANCE PIREPLACE
Sub~ect Matter of the Invention
This invention relates to a 2ero clearancefireplace construction for installation in new
construction or, in some instances, in existing
structures. In particular, the present invention
relates to a fireplace that makes use of an outer
shell and inner firebox that define a convection air
heat exchange passage between the two for heating
the interior of a room by movement of air about the
sides and bottom of the firebox to and from the
room, while combustion air within the firebox is
separately introduced into the firebox and is
physically isolated from the room interior.
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Background of the Invention
Zero clearance fireplaces of the type with which
this invention is concerned have been known for some
time. These fireplaces generally provide a firebox
having a combustion chamber within an outer æhell,
about which air may be circulated to and from the
room. There is no required clearance between the
outer shell and the studwork or other structures
within which it is retained. The combustion chamber
within the firebox is physically separated from the
convection air used to heat the room interior. In
constructions heretofore in use, including a
fireplace construction, exemplified by U.S. Patent
No. 4,574,773, issued March 11, 1986 to Moughamiam,
the firebox opening has been closed by a
guillotine-type glass panel or door that slides in
lateral slides or channels. Similar constructions
have been used and disclosed in other patents
including U.S. Patent No. 4,169,459, issued October
2, 1979 to Shaw: U.S. Patent No. 1,213,173, issued
January 20, 1917 to Evans; U.S. Patent No. 244,397,
issued July 19, 1881 to Matthews: and U.S. Patent
No. 579,987, issued April 6, 1897 to Jordan. These
and other prior art references including U.S. Patent
No. 1,726,874, issued September 3, 1929 to Mumford;
U.S. Patent No. 2,803,241, isæued August 20, 1957 to
Chapla; U.S. Patent No. 4,287,871, issued Septe~ber
8, 1981 to Schumann: U.S. Patent No. 2,775,239,
, 1". .' ' .
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1~90~(16
issued December 25, 1956 to Bucci; U.S. Patent No.
4,294,224, issued October 13, 1981 to Luther; U.S.
Patent No. 4,086,906, issued May 2, 1978 to
Reichgut; U.S. Patent No. 4,183,348, issued January
15, 1980 to Smith; U.S. Patent No. 4,270,514, issued
June 2, 1981 to Berry: U.S. Patent NO. 4,059,091,
issued November 22, 1977 to Hobb; U.S. Patent No.
579,987, issued April 6, 1897 to Jordan; U.S. Patent
No. 244,397, issued July 19, 1881 to Matthews; U.S.
Patent No. 4,271,815, issued June 9, 1981 to
Johnson: U.S. Patent No. 4,572,156, issued February
25, 1986 to Lentz: and U.S. Patent No. 4,576,141,
issued March 18, 1986 to Lillard, generally disclose
the use of guillotine-type glass door closureR in
combination with screen closures for fireplace
constructions. Nonetheless, these prior art
fireplaces appear to have inherent air leaks from
the combustion chamber because the glass door seal
against the combustion chamber is not particularly
tight, In these prior art constructions, spaces
between the glass door and the periphery about the
combustion chamber opening permitted movement of the
air between the combustion chamber and the room.
Such air movement makes these fireplaces less
efficient.
In addition, the arrangements disclosed in the
prior art do not provide suitable means for
maintaining a clean glass door. Means are not
l.Z90~06
provided for minimizing deposit of soot on the inner
surface of the glass door or for facilitating the
cleaning o~ this glass door on both sides. In
addition, those prior art devices in which glass
doors were closed in a guillotine-type action,
involved hand-operated closing mechanisms.
Additionally, these systems had balancing systems,
such that the glass door would remain closed if
unattended even if not positively locked in a down
position. In those systems, no means were provided
for easily opening the glass door from within the
combustion chamber. As a result, there is an
inherent possibility that the glass doors disclosed
in prior art ~uillotine systems might trap a
youngster inside the combustion chamber.
These prior art systems, moreover, do not lend
themselves for installation in a variety of designs
and styles.
Summary of the Invention
The foregoing problems are largely overcome in
the present invention. Additionally, the present
invention provides a number of other improved
features that were not available in fireplace
constructions heretofore in existence.
The present invention provides a high quality
and efficient alternative to conventional masonry
fireplaces. The present invention provides a
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fireplace that is capable of being made to appear as
a traditional masonry fireplace with substantial
visual appeal. In the present invention, the
fireplace is provided with a refractory lined fire
chamber similar to a conventional fireplace.
Additionally, the present invention provides a
guillotine-operated glass door that provides an
unobstructed view of the fire. The door and the
covering screen are moved between open and ciosed
positions with easily operable controls and, in a
preferred embodiment, are operable by motor power.
The present invention provides a system in which
heat output can be maximized with the ability to
design the product with heating efficiency and
emissions complying with E.P.A. regulatory
reguirements proposed for affected solid fuel
appliances for the year 1988. Fireplaces made in
accordance with the present invention will generate
more useful heat than standard masonry fireplaces
and will be comparable in heat generation to other
zero clearance heat producing units, while
nonetheless maintaining a standard masonry fireplace
appearance. The present invention also provides
means for cleaning the inside surface of the qlass
door when the fireplace is in use through movement
of hot gases across the inner surface of the glass
door.
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Thus, it is an object of the present invention
to provide a fireplace construction of the type
generally described, having a glass door that forms
an airtight seal over the opening in the firebox
combustion chamber only when the door is in its
lowermost closed position.
A further object of the present invention is to
permit movement of the sliding glass door in a
vertical direction without frictional engagement of
the door or its frame against the firebox, thus
permitting ease in moving the door into an open or
stored position from its closed or sealed position.
A further object of the present invention is to
provide a fireplace construction having a glass door
in which particulate deposit on the inside surface
of the glass door is minimized due to the air flow
on the inside of the combustion chamber, and in
which the glass door may readily be pivoted open for
cleaning on both sides of the door.
A further object of the present invention is to
provide a means for preventing the glass from
accidentally moving upward in its vertical track
when the glass door is pivoted in its open position
for cleaning.
A further object of the present invention is to
provide a motorized means for opening and closing
the glass door.
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Another object and advantage of the present
invention is to provide means for maintaining the
glass door normally fully open if left unlatched, or
if the glass door is closed, to provide means that
permit it to be readily opened if positively pushed
from within the combustion chamber. This feature
minimizes the likelihood of trapping a child in an
airtight combustion chamber.
Another object of the present invention is to
provide a more efficient fireplace by effectively
sealing the firebox from the room, thus preventing
heat loss as the fire dies out.
A further object of the present invention is to
provide an improved fireplace construction having
the appearance of a masonry fireplace in which both
the glass door and screen cover completely disappear
within the system when these components are not in
use.
In the present invention, there is provided a
fireplace construction having means for selectively
sealing the opening in the front of the combustion
chamber, consisting of a glass door that is moved on
a guillotine-like system to and from a closed
position over the opening in the firebox. Sealing
means on the glass door tightly engage the periphery
of the firebox opening to preclude movement of air
between the room and the firebox when the glass door
is in a closed position. The invention also
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contemplates a guide means which disengages the door
from its air-sealing relation with the firebox
before movement of the door into a storage position.
Brief DescriPtion of the Drawings
The objects and advantages of this invention may
be more clearly understood from a consideration of
the drawings in which:
FIG. 1 is a perspective front view of a
fireplace embodying a preferred form of the
invention;
FIG. 2 is a somewhat schematic perspective view
of the embodiment of FIG. 1 with outer components
removed
FIG. 3 is a cross-sectional view taken
essentially along the line 3-3 of FIG. l;
FIG. 4 is a cross-sectional view taken along the
line 4-4 of FIG. 3~
FIG. 5 is a cross-sectional view taken
essentially along the line 5-5 of FIG. 4 with the
door in a down position:
FIG. 6 iS a cross-sectional view taken along the
same line in FIG. 4 as FIG. 5, but with the door in
an up position:
FIG. 7 is a fragmentary enlarged portion of FIG.
6 with components broken away;
FIG. 8 is an enlarged portion of FIG. 6 similar
to that of FIG. 7, but with the door slightly raised:
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FIG. 9 is a fragmentary cross-sectional view
taken along the line 9-9 of FIG. 5; and
FIG. 10 is a cross-sectional view taken along
the line 10-10 of FIG. 2.
Detailed DescriPtion of Preferred Embodiments
The fireplace of the present invention may have
a visual appearance similar to that of the
traditional masonry fireplace with the
conventionally-appearing refractory lined fire
chamber. The unit may be installed with a wide
selection of decorative components, including, for
example, a mantle that gives the unit all the
appearances of a conventional masonry fireplace.
The fireplace is a zero clearance unit that is
designed to fit into a chase that is approximately
24 inches by 48 inches, or slightly larger.
Typically, the fireplace may have an opening of 36
inches. The outer shell of the unit may be
appropriately and conventionally secured to studs or
other supporting structure in a conventional manner.
The fireplace 1 (FIG. 1) is designed for
installation in a room having a wall 2. The unit is
provided with a firebox 3 having a stovepipe, or
exhaust 4. The firebox 3 is formed with walls 5
(FIG. 4), a floor 6 (FIG. 3) and top 7 that define a
combustion chamber 8. The combustion chamber may be
lined with refractory brick 9. Other conventional
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-- 10 --
fireplace components such as a damper 10 may be
provided. The floor 6 of the firebox is positioned
in spaced relation to the room floor 11 by a bottom
frame member 12. This bottom frame member 12 is
formed with a forward wall 13 spaced from the
forward end of the firebox 3 and is interconnected
to it by a rearwardly-extending top wall 14 to form
a plenum~ e member 15 that interconnects with an
air passage 16 between the floor 6 of the firebox
and the room floor 11. Air slot 17 permits room air
to flow into the plenum-like member 15 and air
passage 16. The forward wall 13 is vertically
aligned with the rear surface of wall 2 and forms
part of an essentially rectangular outer shell 18
that contains the fireplace unit and fits within the
chase. Suitable vertical frame members 19 (FIGS. 4
and 5) secure the walls of the steel shell 18 to the
rear ~urface of the wall 2 and provide a reinforcing
support for the unit. The front of the combustion
chamber 8 is defined by a forward or peripheral wall
having an opening 20 (FIG. 3). The peripheral wall
is defined at its bottom by a shoulder 21 at the
rear end of the wall 14, side flanges 22 (FIG. 4) at
the forward edges of walls 5 (FIG. 4) and the
forward wall 23 (FIG. 3) of the air duct, or channel
24. The air duct 24 is formed across the front of
the combustion chamber at the upper edge of the wall
5 by walls 23, 25, 26 and 27. An air flow slot 28
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is formed in wall 23 at the lower edge thereof to
permit flow of air in the direction of arrow 29
downwardly across a glass door 30 when the door is
in a closed position as illustrated in FIG. 3. The
ends of the air duct, or channel 24, are connected
by a closed passage (not shown) to opposite side
walls of the shell 18. A suitable air control valve
is provided in these closed passages near the side
walls. Means (also not shown) are provided for
selectively connecting the ends of these closed
passages at the air valves to either an outside air
source directly or, if desi.red by the installer, to
a room air source.
The glass door 30 (FIG. 4) includes a continuous
rectangular frame 31 about its sides, top and
bottom, preferably with a sealing member 32 between
the door glass and the frame 31. As best
illustrated in FIG. 2, one vertical ed~e of the
frame 31 is hinged by hinges 33 to an inverted,
U-shaped slider 34. The ~-shaped slider 34 is
provided with legs 35 and 36. A latch system 37, on
~the edge of the leg 36 opposite hinges 33, secures
the door 30 closed. The latch system 37 is
illustrated in detail in PIG. 10. A pair of dogs 38
project outwardly from the side of frame 31. These
dogs are formed with holes 39 that align with holes
40 in bearings 41. Bearings 41, in turn, are fixed
to leg 36 in spaced and aligned relation with one
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another on either side of latch handle 42. Latch
handle 42 is pivotally secured to the frame leg 36
and pivotally enga~eSone end of each of the sliding
pins, or bolts 43. The other ends of these pins, or
bolts 43 are supported for vertical sliding movement
in holes 40. On alignment of holes 39 and 40, the
handle 42 may be pivoted about its pivot point 44,
as illustrated by the phantom outline in FIG. 10, to
slide the pins 43 into locking engagement with the
dogs 38.
The U-shaped slider 34 is supported for vertical
sliding movement by a pair of vertically oriented
channels 45 and 46 (FIG. 2). These channels, 45 and
46, are parallelly aligned with one another on the
outer sides of legs 35 and 36 and are suitably
secured in fixed relation to the outer shell 18 by
suitable bracket means. The slider 34 is guided for
vertical movement in the channels 45 and 46 by means
best illustrated in FIGS. 4-8. The legs 35 and 36
are supported by a plurality of wheels that engage
the channels 45, 46 as hereafter described. The
wheel arrangement, interengaging leg 36 within
channel 46, is similar and symmetrical with respect
to the wheel arrangement that supports leg 35 in
channel 45 as hereafter described. As illustrated
in FIGS. 5-8, wheels 47 and 48 are secured for
rotation about fixed shafts at the upper and lower
end, respectively, of leg 35. The wheels 47 and 48
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~'~90~06
- 13 -
are fixed to the leg 35 to engage and roll against
the inner surface of flange 49 of channel 45 (FIG.
6), when the frame 31 is other than in the closed
position of FIG. 5. When the frame 31 is moved to a
closed position, as illustrated in FIG. 5, the
wheels 47 and 48, along with the frame 31, move away
from flange 49. Leg 35 also carries movable wheels
5~ 50 and 51. Wheels 50 and 52 are rotatably secured
to shafts carried on an L-shaped levers 51, 53,
respectively. These levers support shafts for
wheels 50, 52 at one end, and are engaged by springs
54, 55 at the other end. The springs, in turn, have
one end fixed to the leg 35, so that these L-shaped
levers 51 and 53 may pivot about pivot supports 56
and 57, with the wheels 50, 52 normally maintained
by the springs 54 and 55 under tension against the
inner surface of flange 58 that forms a sidewall of
the channel 45. The flange 58 has openings 60 and
61, spaced apart along the flange 58 a distance
equal to the distance between the wheels 50 and 52.
The flange 58 is also formed with a pair of U-shaped
.offsets 62 and 63, located a distance apart equal to
the distance between wheels 47 and 48.
When the frame 31 is in an up position, as
illustrated in FIG. 6, the frame 31 is aligned with
the channels 45 and 46 with the wheels 47 and 48
pressing against flange 49, and wheels 50 and 52
spring-loaded and pressing against flange 58, as
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~290206
illustrated in FIG. 6. On downward movement of the
frame 31, the wheels 50 and 52 partially move into
the openings 60 and 61, under the influence of the
forces generated by springs 54 and 55, through the
links;51 and 53. At the same time, the wheels 47
and 48, which in an up position bear against flange
49, move away from the flange 49 in the lowermost
closed position into the U-shaped offsets 62 and
63. The openings 60, 61 are si~ed to permit lateral
movement of the frame 31 into an airtight sealing
position only at the lowermost or shut position of
the door 30.
In this lowermost position, the glass door 30,
as illustrated in FIG. 4, effects an airtight seal
over the opening in the forward wall of the
combustion chamber by engagement of a gasketlng
means, or seal 64, carried by the frame 31 with the
forward wall 22 of the firebox 3. The gasketing, or
sealing means 64 includes a resilient seal, secured
by a suitable frame bracket to the rear surface of
the frame 31. The seal, or gasket, is preferably
made of a heat-resistant, compressive insulator
adapted to conform with and close the space between
the glass door 30 and the wall 22 when the door is
in its down, or closed, position. This seal, or
gasket means extends entirely around the frame 31
and provides an effective air seal about the entire
opening into tbe combustion chamber 8 when the door
1290~06
30 is shut. As noted above, the sliding mechanism
is symmetrical with respect to the supports for legs
35 and 36 and, therefore, there is not need to
specifically describe the like elements on legs 36
that support the door 30 for vertical sliding
movement to and from a sealed position over the
combustion chamber. The U-shaped offsets 62 and 63
coupled with the openings 60, 61 function to secure
the glass door in its closed, down position by
engagement with the wheels they respectively engage
when the glass door is closed. The engagement,
however, is such that a slight force on the inside
of the glass door will move it from its sealed
position to a position in which the wheels may
freely move in the channels 45, 46. In this
position, the counterweights hereafter described
cause the door to move upwardly to a normal open
position.
Means are provided for preventing upward
movement of the slider when the door 30 is pivoted
open. These means include a link lOO~that is
pivotally secured at its lower end 101 to an offset
section of the lower end of handle 42. The other
end of link 100 is secured by a pin 103 that is
slideably fixed in slot 104. The link 100 has a dog
105 that projects rearwardly. In a normal closed
position of the door 30, this dog does not encounter
any interference. However, when the latch 42 is
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opened, the dog 105 i~ toggled into an interfering
fit with a stationary stop 106 fixed to the shell 18
on a support member, thus preventing upward movement
of the slider and, consequently, the door 30 which
it supports.
A handle 70 (FIG. 2), secured at one end to the
lower portion of leg 35, may be used to manually
raise or lower the glass door 30. One end of the
handle 70 is secured preferably to the lower end of
leg 35, and the other end of handle 70 projects
through a vertically-extending slot 71 (FIG. 4) in
the vertical frame 19. A similar slot 72 extends
vertically to the right of the glass door in the
frame. The slots 71 and 72 provide air passage
openings that connect the room and the space between
the outer surface of firebox 3 and the outer
enclosure, or shell 18. The area thus defined
permits convection air to move between the room and
the area surrounding the combustion chamber 8, but
with this air isolated from the combustion chamber.
The seal 64 that engages the wall 23 across the
top of the combustion chamber is also positioned
above the slot 28 in the air duct, or channel 24.
Air flowing through the slot 28 is directed
downwardly against the inner surface of glass door
30 and is sealed against escape between the door 30
and wall 23 by the gasket means 6i. This downward
flow of heated air from the combustion chamber
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- 17 -
against the inner surface of the glass, provides an
air sweep which minimizes particulate buildup on the
inner surface of the glass.
A pair of symmetrically arranged means are
provided for automatic raising and lowering of the
glass door 30. This means includes a symmetrically
arranged pair of counterweight and pulley means,
generally illustrated in FIG. 2 at 73 and 74. Each
of these pulley means includes a pulley 75 suitably
supported by shafts fixed to the shell 8. A
counterweight 76 has a cabIe 77 connected at one
end, with the cable extending around the pulley 75
and connected at the other end to a bracket 78. The
bracket 78, in turn, is connected to the legs 35, 36
of the slider 34 by a suitable means, such as a
flange 79, through which cable 77 extendæ, and to
which it is secured by a nut 80 or other suitable
means (see FIG. 9). Flange 79 also secures a belt
or roller chain 81 which extends below a lower
pulley 82 with the other end of the belt or roller
chain 81 connected to the counterweight 76. The
pulley 82 is secured to a shaft 83 that extends
across the bottom of the fireplace and is suitably
supported by bearings on the walls of the shell or
other suitable means.
If desired, an electric motor 84 is operatively
interengaged with the shaft 83 through a gear train
85 that may be of conventional design operated by
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limit switches, by torque load resistance or by
motion detection. The gear train 85 may include a
friction wheel drive system for safety purposes. A
suitable but conventional on-off switch, accessible
from the feont of the unit, may be provided for
motor control. When the motor is controlled by
limit switches, the power to the motor is turned on
by an on-off switch. On movement of the door, a
limit switch is engaged when the door reaches a full
open or closed position, and the power is turned off
and the reversal motor is reversed.
The combined weight of the counterbalance
weights 76 are greater than the weight of the door
30, frame or U-shaped slider 34 and such additional
elements as may be fixed to the slider 34. By
providing counterweights that are heavier than the
door and frame, a positive action holds the door in
an open position.
As illustrated in FIG. 7, the door 30 is secured
in an airtight seal over the opening in the
combustion chamber 8 by engagement of the gasket
means 64 with the forward wall 23 at the upper edge
of the opening in the combustion chamber and by
engagement of the gasket means 64 with shoulder 21
at the lower edge of the opening. The seal is
continuous around the side to provide an airtight
chamber in which the space between the forward wall
of the air duct 24 and the glass door i8
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constricted, thereby providing a narrow passage
through which the air from air duct 24 may pass
close to and against the inner surface of the glass
door.
As illustrated in FIG. 8, the gasket means 64 is
moved laterally from engagement with the forward
walls 23 at the beginning of the upward motion of
the door door. By moving the gasket from engagement
with the wall 23 at the beginning of the upward
movement, wear on the gasket is minimized and the
upward movement of the door 30 is facilitated.
A pair of vertically-extending parallel screen
tracks 86 and 87 (FIG. 4), having opposed C-shaped
cross sections, are aligned vertically on either
side of the fireplace and are suitably secured to
the shell 18. This screen track supports the
opposite side of a wire mesh screen that is adapted
to be slid vertically in the screen tracks 86 and 87
from a position directly across, and over, the
opening in the combustion chamber to an up position
above the opening in the combustion chamber and
concealed behind the wall 2. The screen 88 (FIG. 3)
is positioned in front of the door 30 and must be
raised to an up position, with its lower edge above
the upper edge of the glass door, to permit the
glass door to be pivoted to an open position. When
the screen is in an up position, the glass door 30
may be pivoted open by unlocking the latch syætem 37
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as described above and then swinging the door open
from the full position to its phantom position shown
in FIG. 4.
Prior to opening the door 30 to the position
shown in phantom outlined in FIG. 4, covers, or jamb
doors 8g, 90 and 91 (FIG. 3) must also be opened.
These jamb doors 89, 90 and 91 are provided for
cosmetic purposes to cover the periphery of the
glass door 30. The doors may be suitably styled or
decorated. Jamb doors 89 and 90 are best
illustrated in FIG. 4. These doors are pivotally
supported at their upper and lower ends by hinge
members 92 that interengage one edge of the jamb
doors 89 and 90 with the vertical frame 19 at 93.
The vertical jamb doors 89 and 90 may thus be
pivoted from a closed position, as illustrated in
~IG. 4 in which they cover the side edges of the
door and its frame 31, as well as side edges of the
screen 88. These jamb doors may be pivoted to the
position illustrated in phantom outline when the
door 30 is to be opened. Illustrated in FIG. 3 is
the jamb door 91 which covers the upper edge of the
door frame 31. This jamb door 91 is also pivotally
secured by hinges 92 at its ends to the frame 19. A
spring latch 93 secures the jamb door 91 in an open
position when the glass door is being opened by
frictional engagement with an angle member 94 of the
frame 19.
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When the screen 88 is in its up position to
permit opening of the door 30, it may be secured by
a friction spring 95 that engages the frame of the
screen when it reaches its uppermost position or by
a counterweight approximately equalling the weight
of the screen 88 or other suitable means.
^ Having now described my invention, I claim:
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