Title:
Volute type air-heating furnace and blower
United States Patent 2453912


Abstract:
This invention relates to improvements in volute type furnaces, more particularly furnaces in which a segment of the scroll of the centrifugal blower is heated. One of the objects of the invention is the provision of a furnace of the character stated embodying a minimum of cast material and...



Inventors:
Higley, Frank R.
Application Number:
US47989243A
Publication Date:
11/16/1948
Filing Date:
03/20/1943
Assignee:
BRYANT HEATER COMPANY
Primary Class:
Other Classes:
126/307A, 237/53
International Classes:
F24H3/06
View Patent Images:
US Patent References:
RE19102N/A
2330122Heating apparatus1943-09-21
2313933Heating apparatus1943-03-16
2258790Air tempering device1941-10-14
2245586Hot air heating furnace1941-06-17
2221647Heater and air circulator1940-11-12
2190349Heater1940-02-13
2180212Draft hood for water heaters or the like1939-11-14
2119140Automobile body heater structure1938-05-31
2053036Heat exchange apparatus1936-09-01
2037998Hair drying apparatus1936-04-21
2013237Gas-fired hot air furnace1935-09-03
1877905N/A1932-09-20
1648192Stove1927-11-08



Foreign References:
DE528398C1931-06-29
Description:

This invention relates to improvements in volute type furnaces, more particularly furnaces in which a segment of the scroll of the centrifugal blower is heated.

One of the objects of the invention is the provision of a furnace of the character stated embodying a minimum of cast material and a relatively large proportion of sheet material.

Another object is the utilization of all surfaces of the combustion chamber as heat exchange surfaces.

A further object is the provision of a furnace of this type with a minimum vertical dimension.

Another object is the provision of a furnace of the volute type in which the scroll and the gas burner are so related that the flame and products of combustion naturally follow the contour of the scroll.

Another object is the provision of a scroll the spiral rate of which is designed to compensate for the increased volume of the air when heated.

Still another object is the disposition of tubular heat transfer elements in such manner and the location of a readily removable draft diverter in such relation thereto that the tubular elements are made accessible for cleaning when the diverter is removed.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which: Fig. 1 is an elevational view of a furnace embodying the invention, one wall of the furnace casing being removed and certain of the parts being broken away or shown in section in order to better illustrate the invention; Fig. 2 is an elevational view at right angles to that of Fig. 1, the view being taken substantially on the line 2-2 of Fig. 1; Figs. 3 to 8 inclusive are detail sectional views taken along lines marked 3-3, 4-4, 5-5, 6-6, 7-7, and 8-8 of Fig. 1; Fig. 9 is a diagram illustrating primarily the rate of generation of the spiral of the blower volute; Fig. 10 is a diagrammatic showing, partly in vertical section, of a modified form of the invention; and Fig. 11 is an elevational view of the same on a smaller scale with the outer casing removed.

The present invention has to do with forced air furnaces of the type in which a section of the scroll of a centrifugal blower is a heat exchanger.

One of the important features of the invention is an arrangement in accordance with which a heat exchanger lies outside the blower air stream at the upstream end of the heat exchanger, and gradually extends into the air stream until at its downstream end the heat exchanger lies entirely within the air stream. By virtue of this arrangement a relatively large heat exchanger surface is provided, and the conductor for the hot gases is gradually brought into a position such that connection may be made with a tubular heat transfer element or elements extending across the path of the air in the air conduit. The arrangement also provides a combustion chamber with a heated lower wall spaced above the bottom of the furnace and affording a preliminary air heating surface. The combustion chamber and the hot gas conductor forming a heat exchanger extends along the blower volute, whereby the radial dimension of this part of the furnace is reduced to a minimum. It is preferably positioned beneath the blower and upwardly along one side thereof, whereby a generally horizontal burner flame introduced into the combustion chamber at one end thereof naturally follows the contour of the scroll.

Another feature of the invention is the provision of a combustion chamber and hot gas conductor wherein the hot gas flow is broken up into a plurality of streams which are caused to flow into separate tubular heat transfer elements that extend into and through the air delivery conduit preferably in a diagonal direction, whereby a long heat transfer surface is wiped by the air as it crosses the said elements.

In the embodiment illustrated in Figs. 1 to 9 inclusive, I have shown a sheet metal casing 10 made up of suitable rectangular members. At the bottom of the casing there is a partition wall i which forms part of the supporting means for a casting 12 that constitutes a combustion chamber and hot gas conductor. The wall II occupies a neutral zone so far as air flow is concerned.

An integral flange 13 on the bottom of the casting is fastened by suitable means to the partition wall II. The upstream end of this casting is open and is provided with a surrounding flange 14 to which is secured a transverse partition 15 having an upper inclined wall 16. The walls 15 and 16 extend entirely across the casing and are attached to opposite walls of the latter and the outer edge of the inclined wall 16 contacts a third wall of the casing. In the wall 15 there is an opening 17 registering with the open end of the casting, the opening 17 accommodating a fluid burner indicated diagrammatically at 18, this burner being disposed to project a flame 19 in a generally horizontal direction, and being preferably a long flame burner. The walls 11 and 15 together support the casting 12 upon which the rest of the apparatus within the casing is largely carried.

Upon each side of the casting 12 there is an integral pad or land 20 which takes a spiral direction. To these lands the lower edges of blower side plates 21 are secured. These plates have the usual openings 22 for the entrance of air endwise into the blower. The periphery of the blower wheel is indicated at 23. Its shaft 24 is mounted in inverted bearings 25 carried upon angle bars 26 which are secured to the plates 21 on opposite sides of the openings 22.

By virtue of this bearing arrangement no obstacle is presented to the flow of air diagonally upward into the openings 22.

Air from the blower is delivered into an air outlet conduit 27 which projects through the top of the casing, as illustrated. That portion of the blower scroll which is upstream from the casting 12 is a sheet metal section 28 that is secured to the side plates 21, has a flange 29 that is fastened to one wall of conduit 27, and has a flange 30 that is mounted between and secured to the flange 14 and the partition 15.

A pulley 31 on shaft 24 is driven by a belt 32 from an electric motor 33 which is mounted on a shelf 34 that is hinged at 35 to the adjacent wall of conduit 27. Shelf 34 may be swung into different positions of adjustment and supported there by an adjustable brace 36. 37 represents electric control means for motor 33 comprising a thermostat 38 which extends into the air conduit.

A scroll cut-off element 39 is mounted within the conduit. The side plates 21 of the blower are in effect continuations of opposed walls of conduit 27, or they can be made integral with those walls if desired. That wall of the conduit which is remote from the blower axis is secured to a transverse pad or land 40 of casting 12.

The casting 12 has an outer wall which curves inward radially on either side to join the lands 20, as indicated by the sectional views, Figs. 3 to 5, inclusive. The outer wall and the spiral of the lands 20 gradually approach each other in the down-stream direction until they come together, as shown in Fig. 6.

The inner wall of the casting which forms a section of the blower scrollis straight in a transverse direction at the open end of the casting, but from that point onward to a point slightly upstream from the plane of Fig. 6 the inner wall of the casting is corrugated, the corrugations increasing in depth continuously. The number of these corrugations may vary from a single one to any desired number, three being illustrated. The high and low points 41 and 42 of these corrugations are disposed on opposite sides of the mean volute of the blower. At the plane of Fig. 6 the low points of the corrugations meet and merge with the outer wall of the casting to form a plurality of separate passages 43. From that point on the casting consists merely of separate connectors 44 which may change their cross-sectional shape gradually until in the plane of Fig. 7 they have tear drop, stream-line form.

These connectors 44 receive the lower ends of sheet metal tubular heat transfer elements 45, each of which comprises two stampings having edge flanges welded together and a baffle 46 welded between the flanges at the thick edge of the flue. These baffles are employed in order to prevent channeling of the gases flowing through the heat transfer elements. These elements 45 extend diagonally upward at a steep angle, and their upper ends are joined to castings 47 which are bolted to a wall of the conduit 27, there being passages 48 through the castings which register with a suitably formed opening 48' cut in the conduit wall. An apron 49 bolted to the castings and the conduit wall covers the lower portion of this opening 48', so that gases discharged from the tubular elements must flow through an effectively long narrow opening above the apron.

Aprons of different widths may be employed to thereby adjust the flue restriction as conditions may require.

On the outer wall of the conduit above the passages 48 there is a bracket 50 having an upwardly extending lip offset from the surface of the conduit. A draft diverter 51 is removably hung on this bracket by means of a flange 52 which fits behind the offset lip of the bracket.

This diverter 51 is substantially symmetrical about a plane indicated by the line S in Fig. 1. The diverter is principally open on the bottom and one side. It has a second lip 53 substantially identical with lip 52, and by means of these two lips it may be hung upon the bracket 50 in either of two positions. In one end wall there is an opening surrounded by a flange 54 which is adapted for connection with a flue pipe leading to a chimney. When the draft diverter is mounted as shown in the drawings, the flange 54 extends to the left in Fig. 2. When however the diverter is turned end for end and hangs by means of the lip 53, the flange 54 extends toward the right. Hence by this simple adjustment the diverter may be accommodated to installations in different positions relative to a chimney outlet. This diverter furthermore functions as a manifold, since it collects the gases from a series of tubular elements 45 or the like.

When it becomes desirable to clean out the tubular elements 45, the draft diverter may be lifted off and the apron 49 removed, after which a brush may be inserted through the passages 48 into the tubular elements. The cleaning of the casting 12 may be effected by the insertion of a brush through the open end 17 of the casting. In Fig. 9 certain curves are plotted to indicate diagrammatically the approximate relation of the structural parts of the blower and hot gas conductor, as well as the air travel up to the point where it enters the tubular heat transfer elements. Beginning with the zero point of the blower scroll corresponding with the end of the cut-off 39, the points plotted are at regular 300 intervals, some of which are marked also in Fig.

1. The line 24' represents the axis of the blower 00 wheel. The line 28' represents the volute formed by the surface of the scroll section 28, which extends for 1800 from the zero point. At 180° the volute divides, one line 41' representing the high points .4 of the corrugations of casting 12 and the other line 42' representing the low points 42 of the corrugations. A mean volute between the lines 41' and 42' is indicated by the broken line 55. 56 represents the outer wall of casting 12, which joins the line 42' at 3000. The variation in cross-sectional area of the combustion chamber and hot gas conductor is indicated by the line 57. It will be noted that the rate of generation of the volute remains constant throughout the line 28', or from 0° to 1800. From that point on the mean volute 55 follows a steeper curve accomplished by suitably increasing the rate of recession of the spiral mean, from the spiral center.

This is for the purpose of compensating for thermal expansion of the air by reason of its contact with the hot inner surface of the casting 12.

Air to support combustion may enter the compartment 58 through an opening in the front of the casing, and the air to.be heated may enter the furnace to the rear of the partition wall 15 through the bottom of the housing, as indicated in Fig. 1, or through openings (not shown) provided in the rear wall. The air flows upward over the outer wall of casting 12, which constitutes the first heating stage. It then flows into the end openings 22 of the blower housing and is propelled by the blower wheel against the corrugated inner wall of the cast part of the scroll, which provides a second heating stage. Some of the air leaving the wheel, as indicated by the 2 arrows 60 in Fig. 1, flows over the tubular heat transfer elements 45 in a diagonal direction. In other words, its contact with tubular element 45 is along a relatively extended path. This constitutes a third heating stage. 2 It will therefore be apparent that I have devised a furnace in which the combustion chamber occupies a minimum space and is entirely surrounded by walls that constitute heat exchange members, that the combustion chamber and hot 3 gas conductor is arranged at its upstream end outside the path of air propelled by the blower and gradually enters that path until at its downstream end it is enclosed completely therein, that it merges then with one or more tubular heat 3 transfer elements which extend diagonally through the air conduit which is connected with the discharge from the blower, the air being therefore forced to flow over these tubular elements in a diagonal direction and providing rela- 4( tively long surfaces of contact. It will be observed also that the furnace is one of unusually compact design with the controls readily accessible by the removal of wall panels at one side only of the casing, and that the cleaning of the combustion chamber and the heat transfer elements may be effected with a minimum of effort.

In Figs. 10 and 11 I have illustrated a modified form of furnace in which the construction of the combustion chamber and hot gas conductor is considerably simplified in order to adapt it to sheet metal construction. In this form of the invention the advantages of the more complex form previously described are approximated at a lower cost. A blower wheel 65 is mounted in a volute housing comprising a sheet metal scroll 66 which may have a constant rate of spiral through approximately 1800, corresponding to the line 28' of Fig. 9. That portion 66' of the scroll which is to be heated may have a rate of spiral somewhat higher, preferably corresponding to the mean volute line 55 of Fig. 9. These two portions of the scroll are welded together at 67, and are formed of sheet metal of a width 65 slightly greater than the blower wheel 65.

Suitable side plates are provided for the combustion chamber 69, the blower and an air conduit 70 which receives the air discharged from the blower, the plates on each side being substantially coplanar, as indicated in Fig. 11. The bottom wall of the combustion chamber and hot gas conductor is constituted by a sheet of metal 71 positioned between and attached to the side walls of the chamber. The sheet 71 is curved upwardly to meet the downstream end of scroll section 66' to which it is welded. The rear wall 72 of conduit 70 is welded to the upper end of sheet 7i, and the connection otherwise between the air conduit and the blower housing, including the scroll, is quite rigid. A burner similar to burner 18 of the first described form of the invention may be employed to direct flame in a generally horizontal direction into the combustion chamber.

The downstream end of the scroll section 66' is curved obliquely upward, as shown in Fig. 10, and in this end of the scroll adjacent the rear wall 72 of the air conduit there are one or more .5 apertures 73 which are formed to receive a like number of tubular elements 74, the latter being secured to the scroll around the apertures by means of continuous welds.

Each of the tubular elements 74 is here shown :0 as formed of a single stamping of sheet metal rolled into elliptical cross-section, the longitudinal edges 75 being flanged and welded together. Its upper end is welded to the front wall of air conduit 70 around an aperture 77 therein. 5 The tubular element or elements 74 therefore constitute reenforcing members for the air conduit, as well as constituting conductors for hot gases. The tubular element or elements 74 and the air conduit 70 therefore mutually reenforce 0 each other, and with the scroll 66, 66' in effect constitute a truss. On one of the upstanding members of this truss I support a draft diverter 51, the other member of the truss assisting in the support of the diverter and of the draft pipe 5 which is connected with the diverter. The rigidity imparted to the air conduit by the reenforeing tubuar elements 74 is of importance also in withstanding shocks encountered in transportation, and enables the furnace to be shipped in 0 fully assembled condition.

The tubular elements 74 extend preferably from the rear of the hot gas conductor 69 upwardly in an inclined direction toward the front of the furnace, with the result that air discharged from the blower wheel and flowing along the surface of the scroll passes over the sides of the tubular elements in a diagonal direction and in a relatively long path. As indicated by the arrows in Fig. 10, the air discharged from the wheel on its upgoing side also passes over the tubular elements in a diagonal direction.

In the foregoing description I have necessarily gone somewhat into detail in order to explain fully the particular embodiments of the invention herein illustrated, but I desire it to be understood that such detailed disclosures are not to be construed as amounting to limitations, except as they may be included in the appended claims.

Having thus described my invention, I claim: 1. In a furnace of the class described, complementary conductor means for heating fluid and blower means for fluid to be heated, having a common heat exchanger wall portion, said blower means including an impeller wheel and a casing therefor having a volute wall extending between side walls to confine and direct discharge from said wheel into a stream having a path of flow leading partially about said wheel, said volute wall including said common wall portion and said portion having corrugations, said corrugations commencing at the end of said common wall portion upstream of said fluid to be heated and extending from said end in the direction of said stream with gradually increasing depth, said conductor means having another wall portion cooperative with said common wall por- wall portion tion to provide passageway for said heating fluid, thereof, wh said other wall portion having connection with common wal the downstream end of said common wall portion single openi at the bases of said corrugations thereof, where- 5 to a pluralit by said heating fluid passageway, along said com- ings at its o mon wall portion, has gradual change from a jacent said single opening at one end to a plurality of open- of combusti ings at its other end. connected w 2. In a furnace of the class described, comple- 10 of said comr mentary conductor means for heating fluid and 4. In a ft blower means for fluid to be heated, having a means for f common heat exchanger wall portion, said blow- changer wa] er means including an impeller wheel and a cas- ing an impe ing therefor having a volute wall extending be- 15 ing a volute tween side walls to confine and direct discharge walls to cot from said wheel into a stream having a path of wheel into flow leading partially about and thence away ing partiall from said wheel, said volute wall including said wheel, mear common wall portion and said portion having 20 said volute corrugations, said corrugations commencing at greater rat the end of said common wall portion upstream of mainder of said fluid to be heated and extending from said thermal ex end in the direction of said stream with gradu- correspondi ally increasing depth, said conductor means hav- 25 5. In a fl ing another wall portion cooperative with said means for 1 common wall portion, to provide passageway for changer wa said heating fluid, said other wall portion hav- ing an impd ing connection with the downstream end of said ing a volute common wall portion, at the bases of said corru- 30 walls to co: gations thereof, whereby said heating fluid wheel into passageway, along said common wall portion, ing partial] has gradual change from a single inlet at one wheel, mea end to a plurality of outlets at its other end, and tion of saic tubular heat transfer elements connected to said 35 a greater r outlets and disposed to lead heating fluid there- wall portio from obliquely across said path of flow of the fluid to be heated.

3. In a furnace of the class described, complementary conductor means for combustion prod- 40 The folio ucts and blower means for fluid to be heated, hav- file of this ing a common heat exchanger wall portion, said blower means including an impeller wheel and a U casing therefor having a volute wall extending Number between side walls to confine and direct dis- 45 Re. 19,102 charge from said wheel into a stream having a 1,648,192 path of flow leading partially about and thence 1,877,905 upwardly away from said wheel, said volute wall 2,013,237 including said common wall portion and said 2,037,998 portion constituting approximately that quad- 50 2,053,036 rant of said volute wall which changes said 2,119,140 stream upwardly from horizontal, said volute 2,180,212 wall having corrugations, said corrugations com- 2,190,349 mencing at the end of said common wall portion 2,221,647 upstream of said fluid to be heated and extend- 55 2,245,586 ing from said end to the other end with gradu- 2,258,790 ally increasing depth, said conductor means hav- 2,313,933 ing another wall portion cooperative with said 2,330,122 common wall portion, to provide a combustion chamber and passageway for said combustion products, said other wall portion having connec- Number tion with the downstream end of said common 528,398 , at the bases of said corrugations ereby said passageway, along said i1 portion, has gradual change from a ng for horizontal inlet at one end y of upwardly directed outlet openther end, burner means disposed adinlet opening to direct its products n along said passageway, and means rith said outlet openings for removal bustion products.

irnace of the class described, blower luid to be heated, having a heat ex11 portion, said blower means includller wheel and a casing therefor havwall extending between parallel side ifine and direct discharge from said a stream having a path of flow leady about and thence away from said is for heating a segmental portion of wall, said heated wall portion having a e of spiral recession than the resaid volute wall, to compensate for pansion of said stream within the ng portion of said casing.

urnace of the class described, blower fluid to be heated, having a heat ex11 portion, said blower means includeller wheel and a casing therefor have wall extending between parallel side nfine and direct discharge from said a stream having a path of flow leadly about and thence away from said ns for heating a downstream end pori volute wall, said end portion having ate of spiral recession than the volute n upstream thereof.

FRANK R. HIGLEY.

REFERENCES CITED wing references are of record in the patent: NITED STATES PATENTS Name Date Dibble ------------ Mar. 6, 1934 Prell ------------ Nov. 8, 1927 LeGrand ---------- Sept. 20, 1932 Funk ----- ----- Sept. 3, 1935 Norquist -------- Apr. 21, 1936 Jones ------------- Sept. 1, 1936 Payne ---------- May 31, 1938 Morrow ----------- Nov. 14, 1939 Beam ------------- Feb. 13, 1940 Mooney ---------- Nov. 12, 1940 Holmann -------- June 17, 1941 Murphy ----------- Oct. 14, 1941 Goerg ------------ Mar. 16, 1943 Higley ---------- Sept. 21, 1943 FOREIGN PATENTS Country Date Germany---------- June 29, 1931