U.S. patent number 3,765,389 [Application Number 04/846,708] was granted by the patent office on 1973-10-16 for heater apparatus with controlled air and fuel intake.
This patent grant is currently assigned to Fletcher-Henchel Thermal Industries, Ltd.. Invention is credited to Herbert H. Henchel.
United States Patent |
3,765,389 |
Henchel |
October 16, 1973 |
HEATER APPARATUS WITH CONTROLLED AIR AND FUEL INTAKE
Abstract
An engine pre-heater comprising a pair of concentric screens
mounted in one end of a pear-shaped swirl chamber and forming a
combustion chamber in which diesel fuel vapors are mixed with
forced air delivered from a fan through the swirl chamber and from
which oil residues are forced along a flow path extending to the
other end of the swirl chamber to a drain.
Inventors: |
Henchel; Herbert H. (Grosse
Pointe, MI) |
Assignee: |
Fletcher-Henchel Thermal
Industries, Ltd. (Oshawa, Ontario, CA)
|
Family
ID: |
25298716 |
Appl.
No.: |
04/846,708 |
Filed: |
August 1, 1969 |
Current U.S.
Class: |
123/142.5R;
431/195; 431/336; 431/20; 431/121; 431/201; 431/352 |
Current CPC
Class: |
F02N
19/10 (20130101); F02B 3/06 (20130101) |
Current International
Class: |
F02N
17/06 (20060101); F02N 17/00 (20060101); F02B
3/00 (20060101); F02B 3/06 (20060101); F02n
017/02 (); F23d 005/00 (); F23d 015/02 () |
Field of
Search: |
;123/142.5 ;60/63
;431/201,20,336,352,121,195 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Goodridge; Laurence M.
Assistant Examiner: Cox; Ronald B.
Claims
I claim:
1. A heater for an engine or the like comprising:
a fuel pot,
a combustion chamber formed above said fuel pot,
a closed swirl chamber having a side wall spaced from and
surrounding said combustion chamber and said fuel pot,
forced air inlet means in said swirl chamber and spaced from said
combustion chamber and said fuel pot and establishing a
predetermined path of air flow to said combustion chamber including
a path portion extending away from said fuel pot, and
fuel residue removal means in said swirl chamber and spaced from
said fuel pot and located in said path portion whereby fuel residue
is carried by the air flow along said path portion to said removal
means.
2. The invention as defined in claim 1 and said fuel residue
removal means being located closely adjacent said side wall beyond
said forced air inlet means opposite said fuel pot and said
combustion chamber.
3. The invention as defined in claim 1 and said swirl chamber being
elongated and said fuel pot and said combustion chamber being
located at one end of said swirl chamber and said air inlet means
being located at the other end of said swirl chamber.
4. An engine pre-heater comprising:
an elongated enclosed burner housing having a bottom wall, a top
wall, and a side wall defining an air chamber,
a fuel pot at one end of said burner housing,
burner means at the one end of said housing defining a combustion
chamber above said fuel pot,
air inlet passage means connected to said aIr chamber at the other
end of said burner housing,
fan means connected to said air inlet passage means to force air
through the air chamber to the combustion chamber,
and said inlet passage means including a first vertically extending
portion connected to the atmosphere,
a second vertically extending portion spaced from said first
vertically extending portion and being of equal length and
connected to the air chamber through said top wall of said burner
housing, and
an intermediate cross-over portion therebetween and defining a
generally U-shaped flow path reducing turbulence of the air
delivered to the air chamber.
5. The invention as defined in claim 4 and having a curved elbow
connected to said second vertically extending portion and extending
into said burner housing and having a discharge opening facing said
fuel pot and burner means and directing the air toward the
combustion chamber in a path generally transverse to the
longitudinal axis of said fuel pot and said combustion chamber.
6. An engine pre-heater comprising:
an elongated burner housing having top, bottom, and side walls and
being closed except for an outlet opening for products of
combustion in the top wall at one end of the housing and an inlet
opening for combustion air in the top wall at the other end of the
housing,
a perforated outer cylindrical screen mounted in said outlet
opening and extending into said burner housing and terminating
closely adjacent the bottom of said burner housing,
a fuel pot located below said perforated cylindrical screen and
connected to a source of fuel,
a perforated inner cylindrical screen mounted in said fuel pot and
extending upwardly within said perforated outer cylindrical screen
and terminating below the top of said burner housing,
a combustion chamber defined by said perforated outer cylindrical
screen and said perforated inner cylindrical screen,
fan means connected to said air inlet opening to cause a flow of
combustion air from the atmosphere through the housing, and
an elbow type conduit connected to the inlet opening and extending
into the housing and directing combustion air from the one end of
the housing to the other end of the housing onto and through said
perforated outer cylindrical screen and into said combustion
chamber and creating a zone of high molecular activity in the
combustion chamber.
7. The invention as defined in claim 6 and the flow of air causing
a flow of fuel residue from the fuel pot along the bottom of the
burner housing, and residue removal means in said burner housing in
the flow path of the fuel residue and located in spaced
relationship to the fuel pot to receive and remove fuel residue
from the fuel pot.
8. A heater adapted to burn a liquid fuel, such as diesel fuel,
having a burnable constituent and an unburnable constituent during
continuous self-sustaining operation and comprising:
pot means to hold a quantity of the liquid fuel with a free upper
surface maintained at a predetermined level within the pot
means,
burner means extending upwardly from the pot means and defining a
combustion chamber located above the pot means and the free upper
surface of the liquid fuel, heating means to heat and vaporize the
burnable constituent of the fuel for delivery of fuel vapor to the
combustion chamber,
an air chamber surrounding said pot means and said burner means to
delivery combustion air to said combustion chamber, and
drainage means located in said air chamber beyond said pot means to
continuously drain the unburnable constituent during continuous
self-sustaining operation.
9. The invention as defined in claim 8 and having air delivery
means to establish a flow path of air through said air chamber to
said combustion chamber, said drainage means and said pot means
being located in said flow path whereby the unburnable constituent
is carried by the air from the pot means to the drainage means.
10. The invention as defined in claim 9 and wherein said air
chamber being elongated and comprising:
a first side wall portion being located relatively closely adjacent
said pot means,
a second side wall portion being spaced from said pot means a
greater distance than and located opposite said first side wall
portion, said air delivery means extending into said chamber
between said pot means and said second side wall portion and having
a discharge opening facing said pot means and said first side wall
portion to establish an air flow extending from said pot means to
said first side wall.
11. The invention as defined in claim 10 and said first side wall
portion and said second side wall portion being arcuate and
connected by generally tangentially extending side wall portions,
said flow path extending from said first side wall portion along
said tangentially extending side wall portions.
12. The invention as defined in claim 11 and said drainage means
being located between said air delivery means and said second side
wall portion.
13. The invention as defined in claim 12 and said drainage means
comprising an opening in the bottom of said air chamber spaced
inwardly from said second wall portion and centrally located on a
line extending between the centers of the first wall portion and
the second side wall portion.
14. The invention as defined in claim 13 and said air delivery
means being spaced inwardly from said second side wall portion to
facilitate flow of air from said first side wall portion along said
tangentially extending side wall portions to said second side wall
portion.
15. The invention as defined in claim 14 and the flow path of air
in said air chamber being such as to establish a low pressure zone
and to hold the unburnable constituent over said drainage
means.
16. A heater adapted for continuous self-sustained burning of a
vaporizable liquid fuel comprising:
fuel pot means for holding a quantity of the liquid fuel,
burner means extending above said fuel pot means and defining a
combustion chamber thereabove receiving vaporized fuel
therefrom,
an elongated air chamber extending laterally from said burner means
for supplying air to said combustion chamber,
a first side wall portion of said air chamber being spaced closely
adjacent said fuel pot means and said burner means, a second side
wall portion of said air chamber opposite said first side wall
portion being located more remotely from said fuel pot means and
said burner means than said first side wall portion,
forced air supply means for supplying combustion air to said air
chamber,
an air inlet conduit connected to said forced air supply means
extending into said air chamber between said second side wall
portion and said fuel pot means and said burner means and having an
air inlet opening facing said first side wall portion and said fuel
pot means and said burner means and directing incoming combustion
air theretoward.
17. The invention as defined in claim 16 and wherein said fuel pot
means and said burner means are generally cylindrical and are
concentric, said first side wall portion being arcuate and
concentric with said fuel pot means and said burner means.
18. The invention as defined in claim 17 and wherein said second
side wall portion being arcuate and connected to said first side
wall portion by tangentially extending side wall portions.
19. The invention as defined in claim 18 and wherein said air inlet
conduit includes a cylindrical tubular portion extending parallel
to said burner means and being concentric with said second side
wall portion, an elbow portion curving toward said burner means,
and an outlet portion extending toward said burner means.
20. The invention as defined in claim 19 and said air inlet conduit
being spaced inwardly from said second side wall portion to provide
an air flow passage therebetween.
21. The invention as defined in claim 20 and having a fuel residue
drainage opening connected to said chamber and located between said
air inlet conduit and said second side wall portion.
Description
BACKGROUND AND SUMMARY OF INVENTION
This invention relates to an engine pre-heater for use with
internal combustion liquid-cooled engines (diesel or gasoline),
which are used by vehicles operating on the highways, off-the-road
earth-moving and stationary equipment. The function of the heater
is to pre-heat the engine coolant, making normal engine-starting
possible in cold weather. The engine pre-heater also eliminates the
need for conventional engine warm-up periods during which engine
efficiency is quite low and thereby acts as an anti-pollution
control as well as reducing fuel costs. Furthermore, the pre-heater
itself is extremely clean burning and produces no substantial
amounts of carbon or other residue. The invention involves
improvements in heater apparatus of the type disclosed in U.S.
Pats. No. 3,072,176 and No. 3,234,928, the disclosures of which are
incorporated herein by reference.
While the pre-heater of the present invention may be used with
other types of fuel (e.g., gasoline), one of the primary advantages
of the present invention is the provision of engine pre-heater
apparatus which is able to vaporize any grade of diesel fuel and
burn vaporized diesel fuel containing substantial amounts (e.g., 20
percent) of oil ordinarily provided in commercial diesel fuels for
lubrication of engine cylinder walls. It has been discovered that
in order to successfully burn such diesel fuel, it is necessary to
vaporize the liquid fuel and to separate and remove the oil. This
oil, which those skilled in the art refer to as the "back-end," is
heavier than the balance of the fuel and does not burn or vaporize.
Therefore, means must be provided to separate and remove the oil to
prevent accumulation in the heater apparatus in sufficient
quantities to terminate combustion.
In order to more completely vaporize the liquid fuel, the burner
apparatus is arranged to concentrate the heat of combustion in the
fuel burning area and to create turbulence in the burning area by
use of temperature differentials and shock waves and a high degree
of molecular activity. As a result, in the burning area, there is
explosion-like activity indicating high energy molecular movement
which causes vaporization and complete burning of all but the
distillation residue back-ends which collect as residue on the
bottom of the combustion chamber and which are constantly removed
therefrom jacket heater operation. jacket.
The pre-heater apparatus is associated with the engine cooling
system in a new and improved manner providing a thermosiphon system
for circulating the coolant through the engine water jacket. The
heater apparatus includes a vertically extending coolant jacket
with a coolant outlet at the top of the jacket located somewhat
lower (e.g., at least approximately one-half inch) than the engine
block coolant inlet and with a coolant inlet at the bottom of the
jacket. The system includes means to hold coolant in the coolant
hacket to maximize heating of the coolant by delaying the
circulation of the coolant through the coolant ja ket. In the
preferred embodiment, the heater apparatus is formed as a
self-contained portable unit which may be mounted closely adjacent
the engine or spaced some distance therefrom.
The size, shape and position of the burner housing and combustion
chamber apparatus is extremely important. The burner includes an
elongated swirl chamber, having a somewhat pear-shape configuration
in the presently preferred embodiment, to which combustion air is
delivered under pressure and caused to move therewithin in a
particular flow pattern. To this end, a new and improved air
delivery system is provided by the present invention.
The burner housing includes a fuel pot having a relatively small
size in which a relatively small amount of fuel is maintained as
compared with prior art devices. For example, approximately 20 cc
of fuel are kept in the heater fuel pot in the present invention,
whereas fuel pots having a capacity of approximately 60 cc of fuel
or more have been utilized in prior art devices. Furthermore, in
the present invention, the fuel delivery system and the shut-off
apparatus are arranged to maintain a full fuel pot both during and
after heater operation. To this end, new and improved means of
terminating heater operation are provided.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a somewhat schematic side elevational view of
illustrative apparatus embodying the principles of the
invention;
FIG. 2 is another side elevational view of a portion of the
apparatus shown in FIG. 1;
FIG. 3 is still another side elevational view of a portion of the
apparatus shown in FIG. 1;
FIG. 4 is an exploded view, partly in section, of a portion of the
apparatus shown in FIG. 1;
FIG. 5 is a perspective view in cross section of a portion of the
apparatus taken generally along the line 5--5 in FIG. 2; and
FIG. 6 is a plan view of the apparatus shown in FIG. 4 taken along
the line 6--6.
DETAILED DESCRIPTION
Referring now to FIG. 1, in general, the pre-heater apparatus is
shown to comprise electrical means 10, an air delivery system 11,
burner apparatus 12, chimney-heat exchanger apparatus 13, coolant
jacket apparatus 14, a fuel system 15, and timer means 16, all of
which are mounted on suitable support means 18. In the presently
preferred arrangement, the pre-heater apparatus is enclosed as a
unit in a metal case measuring 13 1/2 inches high by 10 inches wide
by 7 3/4 inches deep with external connections for inlet and outlet
hoses, battery and fuel pump wires. The pre-heater fuel system 15
comprises fuel pump means 20, float bowl means 22, and shut-off
valve means 24. The air system comprises a radially discharging
impeller type blower fan means 26, FIG. 3, restricted air inlet
means 28, air inlet control valve means 30, air inlet control valve
actuating means in the form of a solenoid 32, and an air delivery
conduit means 34. The burner apparatus, FIG. 4, comprises a burner
housing 36 on which chimney means 13 is mounted. Coolant heating
jacket apparatus 14 is mounted circumjacent the chimney means which
is provided with a suitable exhaust conduit.
Referring now to FIGS. 4-6, a swirl chamber 42 is provided within
the burner housing 36 which comprises a box-like bottom member 43,
which may be in the form of an aluminum casting or the like, and a
cover plate member 44. The burner housing is elongated and a
downwardly depending fuel pot 46 is provided in the bottom and
adjacent one end thereof. The level of fuel maintained in the pot
is indicated by line 47. A combustion chamber outlet opening 48 is
provided in the cover plate 44 directly above the fuel pot 46. Fuel
residue outlet means 50, in the form of a removable threaded plug
member having a flow passage extending from the bottom of the
burner housing to the bottom of the member, is provided at the
bottom of the other end of the burner housing opposite the fuel
pot. An air inlet means 52 extends into the burner housing through
the top plate at the other end of the burner housing opposite the
fuel pot.
Fuel pot 46 is of generally cylindrical cross-section
configuration, FIG. 6, and centrally spaced a substantial distance
from the adjacent side wall 54 of the burner housing which is
semi-cylindrical and concentric with the center of the pot at 56.
Side wall 57 of the other end of the housing is also
semi-cylindrical, but of small diameter than side wall 54, and is
connected to side wall 54 by side walls 58, 60 which are outwardly
diverging from the air inlet end of the housing to the fuel pot end
of the housing.
A combustion chamber 62 is provided by an outer burner screen 66
fixedly mounted in the outlet opening 48 in cover plate 44 and
depending from plate 44 into the burner housing above the fuel pot.
Outer burner screen 66 is formed of sheet metal or the like and
extends upwardly through and in sealing association with cover
plate 44. The outside diameter of burner screen 66 is slightly less
than the diameter of the top portion of the fuel pot and the bottom
of the burner screen 66 is located slightly (e.g. one-sixteenth
inch) below and inwardly of the bottom of the burner housing to
provide a residue flow gap 67 therebetween. Screen 66 is
cylindrical and, in effect, except for the one-sixteenth inch gap,
forms a continuation of the side wall 68 of pot 46 and defines the
combustion chamber 62 thereabove. A portion of the screen 66,
intermediate the bottom surface 70 of the burner housing and the
top surface 72 of the cover plate, is perforated by a number of
substantially circular air inlet holes 74, evenly distributed in
horizontal and vertical rows. However, the top row of holes is
spaced a substantial distance from the bottom of surface 72 so that
there is a length 76, FIG. 5, of imperforate screen providing a
deflecting surface for inlet air and defining the only discharge
path from the combustion chamber for the escaping gases and other
products of combustion. The bottom row of holes is also spaced
above the bottom of surface 70 of the swirl chamber to provide a
deflecting surface for the inlet air. In the presently preferred
embodiment, there are a total of 96 air inlet openings of
approximately one-eighth inch diameter located with approximately
one-fourth inch spacing between centers. Each opening is believed
to act as a Venturi and create a kind of shock-wave-explosive
effect within the screen as relatively cool deflected swirling
inlet air on the outside of the screen 66 enters the relatively hot
combustion chamber 62 on the inside of the screen 66. As a result,
the temperature on the outside of the outer burner screen is
substantially less than the temperature on the inside thereof.
A stainless steel wire mesh type generally cylindrical inner burner
screen 80 is concentrically mounted inside the outer burner screen
and is supported by pin-ring means 82 on a seat 83. The bottom edge
84 of the inner screen is located substantially below the bottom
edge 85 of the outer screen, FIG. 5, and below the fuel level line
47 so as to be immersed in the fuel. The upper edge 86 of the inner
screen terminates somewhat less than one-half the distance between
the bottom 70 of the housing and the bottom 72 of the cover plate
so as to be located in the burner flame and to concentrate the heat
of combustion in the top center part of the fuel in the fuel
pot.
A fuel pot inlet 87, FIG. 4, is connected by a line 88 to shut-off
valve 24 and thence by a line 90 to the float bowl 22 and thence by
a line 92 to fuel pump 20 which is connected to a suitable fuel
supply as shown in FIG. 1. The pre-heater operates independently
from the associated engine, but uses the same fuel as the engine
obtained directly from the main fuel tank of the engine through a
separate fuel pump and fuel line. The arrangement is such that the
pot 46 is normally always filled with fuel at or about the level
47. When the preheater is turned off, as will be more fully
described herein, shut-off valve 30 is also closed to smother the
fire and trap a quantity of fuel in pot 46.
For purposes of starting the pre-heater, an electric fuel heater
means 94 is mounted in pot 46 to heat and vaporize the fuel therein
until sufficient heat is obtained for self-sustaining operation. A
fuel igniter means 96 is mounted on the burner housing 43 and
extends through a slot 98 at the bottom of the outer screen 66 as
shown in FIG. 5.
The combustion air delivery system is provided with flow control
means designed to promote particular flow characteristics in the
burner housing. The flow control means includes vertical inlet
conduit 28, the opening 97 to which is opened and shut by valve 30
upon actuation of solenoid 32. The size of the air inlet opening as
defined by the space between the valve 30 and the top of the
conduit 28 in the open position is adjusted to obtain the desired
results in the combustion chamber. The heater is turned off by
closing the inlet opening and stopping the supply of air which will
snuff out the fire and leave the desired fuel supply in the pot 46
rather than allowing the fire to burn out as in prior art
devices.
The fan air inlet conduit 28 communicates with an inlet chamber 100
mounted on the side of fan housing 102. Fan wheel means 26, in the
form of a radial discharge squirrel cage impeller blade type, draws
the air in centrally and axially from chamber 100 and discharges
the air radially and circumferentially through an upwardly curved
discharge elbow 104 and into the discharge conduit 34. An electric
fan motor 106 is drivingly connected to the fan in a suitable
manner. Conduit 34 is substantially U-shaped in side elevation,
FIG. 1, and includes an upwardly extending leg portion 108, a
cross-over portion 110 and a downwardly extending leg portion 112.
Vapor lock prevention means are provided in the form of an air line
113 connecting air passage 112 to the float bowl 22. The air inlet
passages, openings and impeller fan are arranged to obtain a
consistent smooth relatively non-turbulent air flow at the
discharge opening 114, FIG. 4, of chute means 52.
The curvature and position of the discharge chute are such as to
provide a ring-like body of twisting incoming air generally
directed toward the end wall 54 of the swirl chamber. Since the
incoming aIr stays along the inside surface of the discharge chute,
the front surface 118 of the discharge chute is positioned to
direct the upper portion of the ring of air toward the upper
portion of the screen 66 above the upper row of inlet holes and the
bottom portion of the ring of air toward the bottom portion of the
screen 66 below the bottom row of inlet holes. This arrangement
prevents the incoming air from immediately escaping from the swirl
chamber and creates the desired turbulence.
Air discharge chute means 52, FIG. 4, directs the air into the
burner housing swirl chamber 42 in a particular manner and is
placed within the swirl chamber in a particular manner for purposes
to be hereinafter described in detail. Referring again to FIG. 6,
the discharge opening 114 is centrally located between the adjacent
side walls 58, 60 of the housing and faces the burner pot 46 and
screens 66, 80. The lower and rear surface 116, FIG. 4, of the
discharge chute is formed on a relatively large radius to provide a
relatively long smooth deflection surface. The front surface 118 of
the discharge chute is slanted upwardly and away from the burner
screens. In the presently preferred embodiment, the air discharge
chute is mounted on the cover of the swirl chamber and held in
place by a set screw (not shown) which permits adjustment of the
position of the discharge opening. The chute is generally
cylindrical copper material and has a 1 1/2 inch outside diameter
at the top and a 1 1/4 inch inside diameter at the bottom. The back
of the chute at the cover is 3/8 inch from the adjacent housing
wall so that the air can pass behind it. The top of the discharge
opening 114 is 1 3/4 inch from the outer screen 66 and the bottom
is 1 5/8 inch from the outer screen and one-sixteenth inch from the
bottom of the housing. With the heater started and the fan means 26
blowing air through discharge chute 52, the air in the swirl
chamber 42 is believed to have a flow pattern comprising a central
flow path of the ring of incoming air indicated generally by arrows
125, 126 extending from the air discharge opening 114 toward the
outer burner screen 66, which causes the bottom and top portions of
the ring of air to deflect therearound as indicated at 128, 129 and
against the far wall 54 of the swirl chamber as at 130 which causes
the air to deflect 180.degree. therearound as at 132, 133. The
deflected air is driven rearwardly along the sides of the swirl
chamber as at 134, 135, 136, 137 and onto the near wall 57 of the
swirl chamber where the air is again deflected 180.degree. as at
138, 139. As a result, there is a swirling mass of air turning and
twisting in many directions (i.e., turbulence), some of which is
being forced through the air inlet openings 74 in the outer burner
screen 66 to provide combustion air in the combustion chamber 62.
The turbulence prevents the intake air from escaping too fast,
resulting in holding adequate air to supply two atoms of oxygen to
one atom of carbon liberated to form carbon dioxide (CO.sub.2). The
air turbulence also counterbalances the electric motor R.P.M. drop
due to lower battery strength. Another result is that there is a
stream of air at the bottom of the swirl chamber moving first away
from the fire pot toward the near wall 54 and then along the sides
of the swirl chamber toward the far wall 57 in the direction of
arrows 134, 135, FIG. 6.
In normal operation of the heater, the combustion chamber 62 is
white hot with the heat of combustion centrally concentrated in and
around and above the inner screen 80 which normally has a cherry
red color and acts as heat transfer means maintaining a high
temperature in the liquid fuel in the fuel pot and forming liquid
particles and vapors that rise from the upper surface of the fuel.
There is a substantial temperature and pressure differential along
the inside and outside surfaces of the outer burner screen 66 which
causes the swirling air to enter the combustion chamber at high
velocity and to react in a kind of shock wave with the rising
particles and vapor to burst the particles and completely vaporize
the fuel in the combustion chamber. The swirl chamber disperses the
relatively cold input air about the outer screen and the
temperature differential between the combustion chamber and the
incoming air causes violent motion of the fuel particles and vapors
and agitates the remainder of the fuel in the fuel pot. As a
result, some of the fuel in the pot attains such high velocity that
it bursts through the surface film of the liquid fuel and escapes
from the liquid as a gas. Some of the fuel is driven from the fuel
surface in the form of small liquid particles which are vaporized
as they rise into the combustion chamber. The fuel and the products
of combustion are driven and drawn into the chimney 13 through the
outlet opening 48 at the top of the outside burner screen, the
swirl chamber 42 and combustion chamber 62 being otherwise sealed
to prevent any significant escape of air along any other route.
In a pre-heater of this type, I have found that back end oil will
not be vaporized and will float on the surface of the fuel and will
eventually choke out the fire if not removed. The fuel oil back end
cannot burn or vaporize because the boiling point required is
higher than that obtained in the pre-heater. During fuel
vaporization, velocity action forces the back end to the surface of
the pot. One of the main advantages of the present invention
resides in the provision of residue removal means in the form of a
flow path extending along the bottom of the swirl chamber from the
fuel pot to the bleeder means 50 whereat the back end residue is
positively discharged from the burner housing. Velocity action in
the pot pushes the residue into the pear-shaped swirl chamber
through gap 67 against the near wall 54 where air turbulence forces
it along the side walls 58, 60 to the rear wall 57. Unexpectedly,
it has been found that the residual removal means appears to work
most advantageously when located some distance from the fire pot
rather than closely adjacent thereto as might be ordinarily
expected. In the illustrative form of the invention, the flow path
from the fuel pot to the bleeder means is provided by gap 67 at the
bottom of the outside burner and by the bottom surface 70 of the
burner housing along which the back end residue is carried by the
air in the swirl chamber in a path which extends from the fuel pot
to the end wall 54 and then along the side walls 58, 60 to the end
wall 57 where it accumulates about the bleeder means 50 and is
removed by drainage therethrough. Diametrically opposed air holds
the residue over the bleeder means where it drains free from the
swirl chamber.
The hot exhaust gases are carried up the chimney 13 an over and
around a vertically adjustable heat exchange baffle means 150 to an
exhaust conduit 41. Threaded adjustment means 151 permits necessary
adjustment of the bottom of the baffle means relative to the flame
which extends from screen 66. Coolant in jacket 14 is heated
thereby and tends to rise from the coolant inlet 152 at the bottom
of the jacket to the coolant outlet 154 at the top of the jacket. A
thermostat 155 is provided to sense the temperature of the coolant
and provide means to control the apparatus. The coolant jacket
outlet 154 is connected by a line 156 through restrictor means 157
to the engine cooling system 158. A similar restrictor means 159 is
associated with the coolant inlet to control flow of coolant
through the coolant jacket. The restrictor means 157, 159 act to
delay passage of the coolant through the heater thereby maintaining
higher coolant temperatures as well as higher heater temperatures.
The inlet 160 to the engine cooling system is located about the
coolant jacket outlet at an elevation sufficient to insure a
thermosiphoning effect, e.g., a distance of one-half inch in the
illustrative embodiment. The engine cooling system is directly
openly connected to the heater coolant jacket inlet 152 by a line
161 without any intervening valves or the like except for the
restrictor means so that the heater coolant jacket will be an
integral part of the cooling system and effective immediately
during start-up to cause a circulation of heated coolant through
the cooling system.
In the presently preferred embodiment, the inside diameter of the
inlet 152 and outlet 154 are the same (i.e. one-half inch) but the
outlet restrictor 157 is larger (e.g., seven-sixteenths ID) than
the inlet restrictor 159 (e.g. three-eighths ID). The difference in
restrictor size helps prevent reverse flow as well as delay flow
and increase pressure.
OPERATION
The pre-heater of the present invention is particularly adapted for
use with engines used commercially in vehicles on and off-the-road
and stationary equipment which use pure anti-freeze instead of
water for coolant. Although ice may form whenever the ambient
temperature drops below +35.degree. due to condensation inside the
heat exchanger and burner housing, the ignition system on the
pre-heater always starts in the time allowed for ignition.
In operation, the heater may be automatically started by timer
means 16 or by a manually operable start-up switch (not shown)
which cause simultaneous or successive energization of the fuel
valve solenoid 162, the fuel pump 20, the pot heater means 94, the
igniter means 96, the air valve solenoid 32, and blower fan means
26 by suitable circuitry (not shown) associated with the vehicle
electrical system and energizer or with a separate electrical
system and energizer. In the presently preferred arrangement,
electric current for the heater is supplied by the vehicle or
engine battery. The current is required for the following items:
electric motor for the fan, air valve solenoid, sump fuel shut-off
valve solenoid, fuel pump, vibrator coil for energizing the igniter
plug and the heating unit. The igniter plug and heater operate for
approximately 3 minutes at 0.degree. and for approximately five to
six minutes at <20.degree.. The electric current consumption at
-0.degree. is approximately 2.325 (12v) and 1.162 (24v) ampere
hours per hour. In any event, the pot heater means 94 heats the
fuel in the pot and causes fuel vapors to rise into the combustion
chamber 69 where they are ignited by the igniter means 96. After a
few minutes operation, sufficient heat will have been generated to
make the combustion process self-sustaining at which time
thermostat means 155 may be employed to shut off the pot heater
means and the igniter means. At this time there is a continuous
vaporization and burning of the fuel in the pot. The level of the
fuel is maintained by the fuel system float bowl and combustion air
is supplied under pressure as hereinbefore described. Coolant in
the coolant jacket is heated and a thermosiphoning effect is begun
with heated coolant rising from the coolant jacket outlet to the
vehicle cooling system inlet and with coolant flowing from the
vehicle cooling system outlet to the coolant jacket inlet. As the
coolant circulates, the coolant is gradually heated until a
substantially uniform vehicle cooling system temperature is
reached. Then the heater apparatus is turned off either
automatically by thermostatic control or manually by de-energizing
the air valve solenoid to close the air valve and smother the pot
fire. The fuel valve is also closed so as to trap a supply of fuel
in the pot and the fuel pump is de-activated. It will be understood
that the exact theory and/or manner of operation of the various
components of the pre-heater may not be completely understood at
this time and that the explanation herein given is intended to be
illustrative of the results obtained rather than an exact theory of
operation.
The heater apparatus is associated with a thermosiphon system for
circulating the engine coolant through the cylinder block coolant
jacket. The heater apparatus includes a 7 and 1/2 inch fire pot and
coolant jacket. It is made with a 2 and 3/4 inch I.D. inner tube
and a 3 and 1/4 inch O.D. outer tube. The coolant jacket is between
these two tubes with a coolant capacity of one and one-quarter
pints. The coolant outlet of the pre-heater needs only to be
one-half inch lower than the engine block coolant inlet to obtain
the thermosiphon function. The pre-heater can be installed several
feet away from the engine.
The pre-heater output temperature rise is from approximately
0.degree. to +205.degree. in less than 10 minutes after ignition,
and this temperature remains constant during the time required to
heat the coolant in the engine block jacket to normal operating
temperature. The time required depends on the engine coolant jacket
capacity (which can be, e.g., 4 to 8 gallons) and the ambient air
temperature, plus the velocity of the wind.
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