US3193265A - Blower - Google Patents

Description

J; A. COWAN July 6, 1965 BLOWER 2 Sheets-Sheet 1 Filed Sept. 30, 1964 INVENTOK Jiimr A (2am; BY 7%??? July 6, 1965 cow 3,193,265

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United States Patent 3,193,265 BLQWER .lames A. ewan, lliarengo, Ill assignor to Chicago Eastern Qorporation, hlarengo, llL, a corporation of Illinois Filed Sept. 39, 1964, Ser. No. 499,424 h Claims. (\Cl. 263-19) This invention relates in general to heating systems. It deals more particularly with a system for heating and circulating substantial quantities of air.

It is, of course, a well-known expedient to use a forced air heating system for agricultural crop drying and the like. Such a system conventionally combines a motor driven blower fan and a gas burner suitably disposed in a housing so that the blower fan drives air through a combustion area where it is heated by burning gas and then directed into a crop drying enclosure. The present invention is specifically concerned with eflicient heating of the driven air by the gas burner.

it is an object of the present invention to provide an improved forced air heating system which assures more efiicient combustion of the gases.

It is another object to provi e a forced air heating system which prevents undesirable recirculation of unburned gases.

it is still another object to provide a system wherein the formation of carbon monoxide is avoided.

It is yet another object to provide a simple and inexpensive burncr assembly which forest-ails recirculation of unburned gases.

It is yet a further object to provide a burner assembly which controls air flow to achieve more complete combustion and avoid carbon monoxide formation.

The foregoing and other objects are realized in accord with the present invention by providing a forced air heating system including a burner assembly which controls the how of air through the combustion area of the system so that recirculation of unburned gases is avoided. Air how is controlled such that more complete combustion is achieved and optimum heating of the air is alforded while the formation of highly undesirable carbon monoxide is avoided.

The invention, both as to its organization and method of operation, taken with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a perspective view of a forced air heating unit embodying features of the present invention;

FIGURE 2 is an enlarged rear end elevational view of the heating unit illustrated in FTGURE 1;

FIGURE 3 is a sectional View taken along line 3-3 of FIGURE 2, with parts removed; and

FIGURE 4 is a sectional view similar to FTGURE 3 illustrating a burner unit embodying features of a modilied form of the present invention.

Referring now to the drawings, and particularly to FIGURES 1-3, a forced air heating unit embodying features of the present invention is illustrated generally at The unit it} includes a generally cylindrical housing 11 formed of sheet steel or the like through which air is driven by a blower assembly 15 mounted within the housing 11. The blower assembly i forces air past a burner assembly 16 which burns a separate mixture of natural or manufactured gas and air in the forced air stream and thereby heats the forced air before it leaves the unit it). Suitable conduiting (not shown) normally is provided for directing the heated air to a crop drying enclosure or the like.

The blower assembly draws airs into the tip-stream EJ932555 Patented July 6, 1965 inlet 2%. of the housing 11 through a guard screen 21 mounted thereon and drives the air past the burner assembly 16 out of the down-stream outlet 22. The downstream outlet 22 is normally connected to the conduiting (not shown) hereinbefore referred to and designed to connect the unit 16 to a corn drying bin, for example.

The blower assembly includes an electric motor 25 mounted concentrically within the housing 11 between a series of radially extending stator blades 26. The stator blades are preferably fabricated of sheet steel and are secured at their outermost ends 27 to the inner surface of the housing 11 by conventional bolt assemblies (not shown). At their innermost ends 2-8, the stator blades 26 are secured to a generally cylindrical casing which supports the motor 25 within its confines on radially disposed brackets 36. The motor 25' is actuated and controlled from a conventional control box 37 mounted on the outside of the housing 11 through a shielded conduit 38 in a well known manner.

The drive shaft 40 of the motor 25 protrudes from its body 41 toward the inlet 2% of the housing 11 and mounts a blower fan 42 for rotation about the longitudinal axis of the housing ll. The blower fan 42 includes a cylindrical rotor 43 and a mounting spider 44 secured thereto by conventional bolt assemblies 45. The spider 54- is a casting which includes a sleeve slipped over the shaft 4 and secured thereto by set screw means (not shown).

Radiating from the cylindrical rotor 43 and secured thereto by welding or the like are a plurality of rotor blades 5%. The rotor blades 5t are of broadly conventional construction and, when rotated with the rotor 43 on the drive shaft 4t, serve to draw air in the inlet end 20 of the housing 11 through the screen 21 and drive it past the stator blades 2-3 hereinbefore described. The stator blades 25 are angulated in cross-section, as seen in FIGURE 3, and thus serve to straighten out the rotational flow of driven air and direct it axially past the burner assembly 16 with a reduced rotational component.

The burner assembly 16 includes a burner ring 55 which might be fabricated of pipe 56 or the like, and formed into What approximates a circle about the longitudinal axis of the housing 11, as illustrated. In the alternative, the ring 55 can also be cast in shape, of course, as it preferably is in practice. The pipe 56 is capped at its free end 57 and connected at its opposite end 58 to a gas inlet fitting 59 inserted in the open end 5% of the pipe adjacent a short straightened section 60 thereof.

The inlet fitting 5h is solidly mounted in the housing ill by any suitable mounting arrangement and extends through the housing into a gas inlet regulator unit secured to the outside of the housing. The inlet fitting 59 supports the burner ring 55 as well as conducting natural or manufactured gas from the regulator unit 65 into the pipe $6. The gas, which in practice is usually propane, is metered through the unit 65 in a controlled manner, as by control valve es, from a source (not shown) secured to the nipple 67.

The propane is mixed in the pipe 56 at a prescribed ratio with air admitted thereto in a well known manner from orifice means (not shown) in the upstream face 7% of the pipe. This combustible mixture of propane and air is then emitted from the pipe 56 through a series of closely spaced burner apertures '71 formed in the downstream face 72 of the pipe 55. The apertures '71 are all formed within the confines of a flame retainer sub-assembly 73 secured to the downstream face 72..

The flame retainer sub-assembly '73 comprises air impervious inner and outer flame retainer walls 77 formed of strip steel or the like welded to the downstream face 72 of the pipe 56 in bracketing relationship with the apertures 71. The walls 7'7 terminate in free edges 78 downstream of the apertures 71. End sections 79 of the sub-assembly 73 interconnect the walls 77 at their opposite ends to complete a flame retainer well 80 shielding the apertures 71 and permitting a combustible mixtureof gas and air to accumulate and ignite after being emitted from the apertures without first being dissipated y the blast of air driven past the pipe 56 from the blower fan 42.

The combustible gas-air mixture is ignited by a conventional spark ignition system as it leaves the mouth 81 of the well 80. The ignition system, which includes a conventional control and transformer box 82 mounted on the housing 11, provides a continuing spark at the mouth 81 through are forming elements (not shown) in a well-known manner.

past the pipe 56 and the heated air is delivered to the aforementioned crop drying enclosure.

To avoid the recirculation of unburned gas, and to Supply sufiicient secondary air to the ignited gas so that complete combustion is achieved and the formation of carbon monoxide, for example, is avoided, the burner assembly 16 incorporates an air shroud sub-assembly 85 constructed and arranged according to the present invention. The air shroud sub-assembly 85 channels and directs a portion of the air driven past the burner assembly 16 transversely across the mouth 81 of the flame retainer well 80.

The converging flow of air across the downstream edges 78 of the walls 77 serves to obviate the suction cifect of negative pressure areas caused by the motor body 41, or the burner ring 55 or the like, and prevent: recirculation of unburned gases upstream. Atthe same time, this air flow pattern supplies additional secondary air to the gas ignited immediately downstream of the V The flame propagated at the mouth 81 of the flame retainer well 80 heats air driven well mouth 81 and assures substantially complete comis secured to the housing 11 by radial brackets 90 and conventional bolt assemblies (not shown).

, The deflector rim 86 comprises an upstream rim section 93 which extends substantially parallel to the axis of the housing 11 and a converging downstream rim section 94 which terminates at a rim edge 5 axially aligned with thetdownstream edges 78 on the flame retainer walls 77. The outer deflector rim forces a portion of the air driven past the burner ring laterally across the mouth 81 of the flame retainer well 80.

Opposite the outer deflector rim 86 in bracketing relationship with the burner ring 55 is an annular air inpervious inner deflector rim 100. The inner deflector rim 190 comprises an upstream rim section 105 extending substantially parallel with the axis of the housing 11 and a diverging downstream section 106 which terminates at a rim edge 107 which lies in a plane approximately axially aligned with the plane in which edges 78 on the flame retainer walls 77 lie.

It will now be seen that driven air immediately adjacent the annular casing 28 surrounding the motor 25 passes outside the inner deflector rim 100-and is directed outwardly over the mouth 81 of the flame retainer well 80. At the same time the outer rim 86 directs air inwardly immediately over the mouth 81 of the flame retainer well 80. Accordingly, the circulation or eddy current flow of those as yet unburned gases backwardly along the outside of the flame retainer walls 77 is eliminated. Furthermore, 'sufiicient secondary air is introduced to the combustion area immediately downstream of the well mouth 81 to achieve complete combustion and the formation of carbon monoxide, for example, is avoided.

The invention has thus far been described only in the context of a forced air heating unit 10 wherein the fan 4-2 is arranged to first drive air past the driving motor 25 and then the burnertassembly 16. FIGURE 4, however, illustrates a unit ltla wherein the blower fan 42a is mounted downstream of the motor 251;. In such case, the rotation of blower fan 42a creates a negative pressure area adjacent to the front of the cylindrical rot-or 43a which in turn tends to cause a reverse air fiow pattern through the center of the inner rim ltltla. To prevent forced air which has already been heated from recirculating through the inside of the inner rim 109a upstream to overheat the blower fan 42a, a slightly modified air shroud sub-assembly a is employed. To this end, a circular closure plate 12% is connected to the downstream edges 107a of the diverging rim sections Idea on the innerdeflector rim a. In all other respects, the forced air heating unit 10a is substantially identical to that hereinbefore described, and illustrated in FIG- URES 1-3. Accordingly, corresponding components are identified by corresponding reference numerals with the addition of the suffix a.

The forced air heating units It) and 16a hereinbefore described effect extremely eflicient heating of the air driven through housings 11 and 11a. Complete combustion is assured with the concomitant avoidance of any significant carbon monoxide formation. In the case of the unit 10a illustrated in FIGURE 4, recirculation of heated air to overheat the blower fan 42a is also prevented.

It should be recognized, of course, that both units It) and 10a are described somewhat diagrammatically. For example, the housings 11 and 110 are frequently twopart assemblies housing the blower assemblies and burner assemblies separately. Furthermore, while embodiments described herein are at the present considered to be preferred, it is understood that various modifications and improvements may be made therein, and it is intended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.

What is desired to be claimed and secured by Letters Patent of the United States is:

1. In a forced air heating system including a housing defining a passage and a blower assembly for forcing air therethrough, the improvement comprising: a burner ring disposed transversely of the longitudinal axis of said passage and adapted to emit combustible gas through outlet means formed in a downstream face on said ring, flame retainer walls extending downstream of said face in bracketing relationship with said outlet means to form a flame retainer well, said walls terminating in downstream edges defining a mouth on said well, and air shroud means bracketing said burner ring, said air shroud means including substantially annular inner deflector means arranged inside said ring and substantially annular outer deflector means arranged outside said ring, said deflector means including converging downstream sections adjacent said mouth for directing a portion of the blower driven air' transversely across said mouth immediately downstream thereof to prevent recirculation of unburned gases upstream and supply suflicient secondary air to assure substantially complete combustion.

2. The improvement in heating system of claim 1 further characterized in that said converging downstream sections terminate in edges which lie in a plane that is in approximately axial alignment with a plane in which said downstream wall edges lie. V

V 3. In a forced air heating system including a housing defining a passage and a blower assembly mounted in adapted to emit combustible gas through outlet means formed in a downstream face on said ring, flame retainer walls extending downstream of said face in bracketing relationship with said outlet means to form a flame retainer well, said walls terminating in downstream edges defining a mouth on said well, and air shroud means bracketing said burner ring, said air shroud means including a substantially annular inner deflector plate arranged inside said ring and spaced a predetermined radial distance therefrom, and a substantially annular outer deflector plate arranged outside said ring and spaced said predetermined radial distance therefrom, said deflector plates including upstream sections extending generally parallel to each other and to said axis, and converging downstream sections adjacent said mouth for directing a portion of the blower driven air transversely across said mouth immediately downstream thereof to prevent recirculation of unburned gases upstream and supply suflicient secondary air to assure substantially complete combustion.

4-. A relatively low pressure forced air heating system for supplying heated air to an enclosure, comprising: a housing defining a passage having inlet means and outlet means, a blower assembly in said passage for forcing air therethrough from said inlet means to said outlet means, burner means disposed in said passage and adapted to emit combustible gas through outlet means formed on a downstream face of said burner means, flame retainer walls extending downstream of said face in bracketing relationship with said outlet means to form a flame re tainer well, and air shroud means bracketing said burner means, said air shroud means including inner deflector means arranged inside said burner means and outer deflector means arranged outside said burner means, said deflector means including converging downstream sections adjacent said mouth for directing a portion of the blower driven air transversely across said mouth immediately downstream thereof to prevent recirculation of unburned gases upstream and supply sufiicient secondary air to assure substantially complete combustion.

5. The system of claim 4 further characterized in that said converging downstream sections terminate in edges which lie in a plane that is approximately axial alignment with a plane in which said downstream wall edges lie.

6. A forced air heating system, comprising: a housing defining a passage having inlet means and outlet means, a blower assembly in said passage including a blower fan for forcing air therethrough from said inlet means to said outlet means, burner means disposed in said passage and adapted to emit combustible gas to outlet means from a downstream face of said burner means, air shroud means bracketing said burner means, said air shroud means including substantially annular inner reflector means arranged inside said ring and substantially annular outer deflector means arranged outside said ring, said deflector means including converging downstream sections for directing a portion of the blower driven air transversely across said mouth to prevent recirculation of unburned gases upstream and to supply suflicient secondary air to assure substantially complete combustion, and closure means extending between said annular inner deflector means for preventing the recirculation of heated air upstream to overheat said blower fan.

7. The system of claim 6 further characterized in that said closure means comprises a generally circular plate secured to said annular inner deflector means around its periphery.

8. A relatively low pressure forced air heating system for supplying heated air to an enclosure, comprising: a housing defining a passage having an inlet and an outlet, a blower assembly in said passage for forcing air therethrough from said inlet to said outlet, a burner ring disposed in said passage and adapted to emit gas through outlet means formed on the downstream face of said burner ring, flame retainer Walls extending downstream of said face in bracketing relationship with said outlet means to form a flame retainer well for supporting combustion of said gas, said wall terminating in downstream edges defining a mouth of said well, and air shroud means bracketing said burner ring, said air shroud means including annular inner deflector means arranged inside said burner ring and annular outer deflector means arranged outside said ring, said deflector means including converging downstream sections immediately adjacent said mouth for directing the first portion of forced air made available to said combustion transversely across said mouth immediately downstream thereof to prevent recirculation of unburned gases upstream and supply suflicient air to assure substantially complete combustion.

9. A relatively low pressure forced air heating system for supplying heated air to an enclosure, comprising: a housing defining a passage having an inlet and an outlet, a blower assembly in said passage for forcing air therethrough from said inlet to said outlet, a burner ring disposed in said passage and adapted to emit gas through outlet means formed on a downstream face of said burner ring, air impervious flame retainer walls extending downstream of said face in bracketing relationship with said outlet means to form a flame retainer well for supporting combustion of said gas, said walls terminating in downstream edges defining a mouth on said well, and air shroud means bracketing said burner ring, said air shroud means including annular inner deflector means arranged inside said burner means and annular outer deflector means arranged inside ring, said deflector means including air impervious upstream sections, and converging air impervious downstream sections immediately adjacent said mouth for directing the first portion of forced air made available to said combustion transversely across said mouth immediately thereof to prevent recirculation of unburned gases upstream and supply sufficient air to assure substantially complete combustion.

References Cited by the Examiner UNITED STATES PATENTS CHARLES SUKALO, Primary Examiner.

Claims (1)

1. 4. A RELATIVELY LOW PRESSURE FORCED AIR HEATING SYSTEM FOR SUPPLYING HEATED AIR TO AN ENCLOSURE, COMPRISING: A HOUSING DEFINING A PASSAGE HAVING INLET MEANS AND OUTLET MEANS, A BLOWER ASSEMBLY IN SAID PASSAGE FOR FORCING AIR THERETHROUGH FROM SAID INLET MEANS TO SAID OUTLET MEANS, BURNER MEANS DISPOSED IN SAID PASSAGE AND ADAPTED TO EMIT COMBUSTABLE GAS THROUGH OUTLET MEANS FORMED ON A DOWNSTREAM FACE OF SAID BURNER MEANS, FLAME RETAINER WALLS EXTENDING DOWNSTREAM OF SAID FACE IN BRACKETING RELATIONSHIP WITH SAID OUTLET MEANS TO FORM A FLAME RETAINER WELL, AND AIR SHROUD MEANS TO FORM A FLAME REMEANS, SAID AIR SHROUD MEANS INCLUDING INNER DEFLECTOR MEANS ARRANGED INSIDE SAID BURNER MEANS AND OUTER DEFLECTOR MEANS ARRANGED OUTSIDE SAID BURNER MEANS, SAID DEFLECTOR MEANS INCLUDING CONVERGING DOWNSTREAM SECTIONS

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