US2227373A - Blower - Google Patents

Description

Dec. 31, 1940. w. o. BEHRENS 2,227,373

BLOWER Filed Feb. 25, 1938 Patented Dec. 31, 1940 UNITED STATES -TENT QFFICE Claims.

The invention relates to blowers and more particularly to the type of blower adapted to deliver separate supplies of air at different volumes or pressures.

The present invention embodies improvements particularly well adapted for use in connection with the burners disclosed in my copending applications, Serial No. 90,232 filed July 11, 1936 and Serial No. 150,279 filed June 25, 1937.

An object of the invention is to provide a new and improved fan blower construction requiring a minimum of horse power expenditure in operation due to its simplicity of construction and the ease of air flow therethrough. More specifically stated, it is an object of the invention to provide a novel rotary fan blower of this type having a single air intake opening, a low pressure outlet and a high pressure outlet, said blower embodying new and improved features of construction rendering it particularly well adapted for efficient operation in supplying low and high pressure air for an oil burner utilizing both primary and secondary forced draft.

Other objects and advantages will become apparent in the following description and from the accompanying drawing in which:

Figure 1 is a longitudinal sectional view of an oil burner embodying the features of the invention.

Fig. 2 is an end view in elevation of a rotary blower with a section of the blower broken away to show the underlying construction.

While the invention issusceptible of various modifications and alternative constructions, I have shown in the drawing and will herein describe in detail, the preferred embodiment, but

it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

The oil burner shown inthe drawing for purposes of disclosure is of the typeadapted to dis- 4:5 charge a turbulent mixture of atomized fuel and oil conditioned for. efficient combustion, preferably into a sealed furnace. The blower of the present invention is embodied in a burner having a primary air nozzle ill for supplying high pressure low volume air to the furnace, said nozzle being coaxially alined with a circumscrib-ing secondary air nozzle ii of generally Venturi shape rigidly secured in and adapted to discharge relatively low pressure high volume air into an end 5 opening l2 in a refractory furnace wall It. A

burner front plate I4 is secured against the exterior of the wall l3 and has an opening IE to receive the nozzles. An annular flange portion [6 of the nozzle I l is secured to the plate M to hold the nozzles in place.

Low pressurehigh volume air is supplied to the secondary air nozzle and relatively high pressure low volume air is supplied to the primary nozzle by means of a rotary blower (indicated generally at ll) enclosed within a housing Hi. The housing 18, together with a cover [9, is suitably supported to form the outer wall of an air passage 29 opening to the nozzle II and to the source of secondary air supply. The cover I9 is formed with a suitably apertured plate member 2| extending transversely oi" the axis of the burner and terminating in an inner ring 22 to provide the stationary element of a damper for throttling the secondary air supply from the blower. A rotary damper member 23, similarly apertured, is operatively disposed against the plate member 2! and is adjustable by means of a rod 25 pivotally connected to one side thereof and extending out of the housing.

The primary air nozzle is mounted on the end of a tube 26 which constitutes the outlet from the source of primary high pressure air. The tube 26 is supported in the ring 22 in spaced relation to the cover plate I!) to provide an inner wall for the secondary air passage 20.

An important feature of the instant invention resides in the provision of a novel blower construction for providing both primary and secondary air to the'nozzles by means of a single unitary rotary fan blower. to the free passage of air therethrough is one of the objectionable characteristics of fan blowers heretofore employed. It is desirable in blowers of this type to provide an air flow path with a minimum of baffle walls and partitions causing scrubbing of the air and an increase in the frictional resistance of the fan to the passage of air therethrough.

To this end, the blower embodied in the present invention is constructed of simple and etficient design to reduce frictional loss. The proportional amounts of primary and secondary air delivered by the fan are controlled solely by the relative width of its peripheral discharge openings, the fan embodying only one axial air intake opening. The frictional loss necessarily inherent in the ordinary compound disk fan having more than one intake opening is thus obviated. The single axial intake opens to a single set of impeller blades defining generally radially extend- Frictional resistance ing air passages through which the air is impelled by the centrifugal force created by rotation of the fan. The radially impelled air is then divided into separate radial streams, part being discharged immediately as secondary low pressure air through a peripheral outlet and the remainder being subjected to an additional impulse to provide primary high pressure air which is discharged peripherally of the fan at a greater radial distance from the axis. Lateral separation of the air stream is not effected until the air reaches the secondary discharge, thus avoiding the necessity for separate partitions and consequent frictional resistance inherent in such partitioned constructions. This simplified fan construction embodies the additional advantages of light weight and compactness, thus reducing the bearing friction and overhang to increase the efficiency of the fan.

The fan or impeller ll, illustrating one embodiment of the invention for purposes of disclosure of the above mentioned principles, comprises a radially extending disk 34 fixed for rotation with a drive shaft 21 extending axially of the burner. Integral with one side of the disk are a plurality of spaced impeller blades 32 slightly inclined to the radius. These blades extend longitudinally of the shaft 21 and at their inner end edges may be slightly spaced therefrom. An annular ring or disk 33 of lesser diameter than the disk 34 is integral with the free side edges of the blades in spaced relation to the disk 34 and defines an axial air inlet opening 28 com municating with the motor housing 43. It will be seen that the disks 34 and 33 and the blades 32 define generally radial passages 29 in communication at their inner ends with the air inlet 28 and discharging peripherally of the fan.

The outer ends of the blades 32 are stepped radially inwardly from the external periphery of the disk 34 to the periphery of the disk 33. Alternating with the narrowed portions of the blades 32, are a plurality of short generally radial blades 32 also integral with the disk 34. The free side edges of the blades 32 and of the narrowed portions of the blades 32 are integral with an annular disk 33 spaced from the disk 34 to define narrowed supplemental air passages 29 communicating at their inner ends with the passages 2 9 and discharging peripherally of the disks 33 and 34 (as indicated at 3!). It will be seen that the inner periphery of the annular disk 33 divides the passages 29 at their outer ends into separate portions longitudinally of the shaft 21. Those portions of the stepped blades 32 lying on the side of the disk 33 toward the disk 33* terminate at the inner periphery of said disk 33 in peripheral discharge openings 33 while those portions of the blades on the inner side of the disk 33 are elongated to define, together with the blades 32 and the disks 33 and 34, the supplemental passages 29*.

Rotation of the fan creates a suction at the inlet opening 28 drawing air through the motor housing 40 and into the passages 29 where it is directed radially by the centrifugal force created by rotation of the impeller. The radially directed stream is divided into separate streams by the disk 33,'part being discharged immediately upon separation through the peripheral discharge opening 30 as secondary air. The remainder is subjected to an additional impulse in the passages 29 to impart a greater pressure thereto and is discharged through the peripheral discharge openings 3| as primary air. Since the air pressure delivered by a rotary disk fan is a function of the tip speed of the blades, it will be apparent that the portion of the air stream delivered through the discharge 3| as primary air will be under greater pressure than that delivered through the openings 33 as secondary air, the external circles of revolution of the stepped blade formation determining the pressures. The discharge 30 may be located at a radial distance from the axis substantially one half that of the discharge 3|. It is preferred that a greater volume of secondary air be provided than primary air, and to this end the secondary air discharge opening 39 is made of greater width than the primary air discharge opening 3!. Accordingly, the proportionate volumes of primary and secondary air delivered may be effectively controlled by providing appropriate relative Widths to the discharge openings.

An internal housing 34 encloses the high pressure side of the fan and, together with a circular baffle or guide plate 35 serves to direct air from the primary air discharge opening to the interior of the tube 23. The housing 34 has an end wall 36 which closely encircles the short portions of the blades 32 adjacent the disk 33, and which together with the housing l3 forms an air passage 31 between the low pressure discharge 3!! and the passage 20 to the secondary air nozzle. The low pressure side of the blower, although smaller in diameter than the high pressure side, discharges substantially parallel thereto into the passage 31 between said housings and hence into the passage 29 to the secondary air nozzle. The nozzles l0 and II may be suitably provided with sets of spaced helical vanes 38 and 39, respectively, said vanes having opposite inclinations to insure an intimate fuel mixture and fine atomization.

It will be apparent from the foregoing that a novel blower contruction has been provided which may be operated with greater efiiciency than has been possible heretofore. Both primary and secondary air may be effectively introduced into the burner by means of a simple and compact blower unit of the type herein disclosed. The air is introduced into the blower through a single axial inlet opening and is impelled radially to a peripheral discharge opening where the air stream is divided, part being discharged through said opening and the remainder, continuing its radial flow, is impelled to a second peripheral discharge opening of greater diameter where it is discharged under greater pressure. Such a construction greatly reduces the frictional resistance to the passage of air through the blower thus increasing the efliciency of the blower and at the same time the weight of the fan is materially reduced resulting in a substantial saving in the cost of manufacture.

As fully described in my copending applications, a cylindrical housing 40 encloses the inlet side of the housing l3, said cylindrical housing having a plurality of air inlet openings 4| opening from the atmosphere. The inner end Wall of the housing 40 is formed with an axial outlet opening 42 communicating with the blower intake 28 and in direct registration and close interfitting relation therewith. The shaft 21 extends into the housing 40 where it may be suitably journaled in spaced bearings 44 and driven by any desired driving means as an electric motor 45. A suitable fuel pump (not shown) may be provided and driven from a worm gear mechanism (indicated at 46) An atomizing cup 41 and fuel nozzle (it are mounted on the inner end of the shaft El for rotation therewith and communicate with an elongated fuel supply tube fill within the shaft. A valve mechanism (indicated generally at 5b) is located at the opposite end of the shaft and is interconnected with the rod 25 for jointly controlling the supply of fuel and secondary air.

I claim as my invention:

1. A rotary fan blower adapted to deliver air under different pressures, said blower comprising a longitudinally disposed drive shaft, a set of longitudinally and generally radially extending spaced impeller blades fixed for rotation. with said shaft, the outer ends of said blades being stepped to provide opposite side portions of different widths and lengths, a radially disposed disk secured to the long side edges of said blades and extending substantially throughout the length of said blades, an annular disk secured to the free short side edges of said blades and defining an axial air inlet opening to the inner ends of said blades, an annular disk secured to the intermediate side edges of the stepped portions of said blades and terminating at a point spaced substantially outwardly from the inner ends of said blades, whereby said blades and said disks define generally radial passages communieating at their inner ends with the air inlet and discharging peripherally in separate stages at difierent radial distances as defined by said stepped blade portions, and separate air delivery means opening respectively fro-m the peripheries of said stepped blade portions.

2. A fan blower for delivering air at different pressures, said fan blower having in combination a drive shaft, a plurality of blades peripherally spaced about said shaft and extending outwardly thereof to define generally radial air passages,

40 each blade having an outer end of stepped formation with one side portion relatively short and having a relatively small circle of revolution, and with the other side portion relatively long and having a relatively large circle of revolution, a 45 closed disk rigidly connected with the long side edges of said blades and fixed on said shaft for rotation therewith, an annular disk rigidly connected with the opposed short side edges of said blades and defining a common axial air inlet 50 passage opening to the inner ends of said radial passages, an intermediate annular disk closely encircling the first mentioned side portion and rigidly connected with the intermediate side edges of said blades in spaced relation to said 55 first mentioned disk to define supplemental air passages, said intermediate annular disk having a radial extent limited substantially to the distance between said circles of revolution, and independent air directing means communicating re- 60 spectively with the outer end edges of the re1atively short side portions of the blades and with the relatively long side portions of the blades for delivering separate supplies of air under different pressures.

3. A blower adapted to deliver separate supplies of air at different volumes and pressures, said blower comprising a drive shaft, a radially extending disk fixed to said shaft for rotation therewith, a plurality of spaced impeller blades 70 integral with said disk and slightly inclined to the radius, a second disk of relatively smaller outside diameter integral with the inner portions of the free side edges of said blades, an axial air inlet in said second disk circumscribing the shaft, said disks and said blades defining generally radial air pas-sagescommunicating at their inner ends with said intake and discharging peripherally, the outer free edge portions of said blades being narrowed in width toward the first mentioned disk and radially inwardly to the periphery of the second disk, anv annular disk integral with the free side edges of the narrowed portions of the blades and fixed in spaced relation to said first mentioned disk, said annular disk extending radially inwardly only to the extent of said narrowed portions, said annular disk together with the narrowed portions of the blades and the outer annular area of said first mentioned disk defining extended generally radial air passages communicating at their inner ends with a longitudinal portion of the first mentioned radial air passages and discharging peripherally of the last mentioned disks, and separate air directing means communicating with said passages for delivering air therefrom.

4. A rotary fan blower adapted to deliver air under different pressures, said blower comprising a longitudinally disposed drive shaft, a set of longitudinally and generally radially extending spaced impeller blades fixed for rotation with said shaft, each of said blades having an. outer end of stepped formation, radially disposed disks along the free side edges of said blades, an axial air inlet in one disk opening to the inner ends of said blades, said blades and said disks defining generally radial passages communicating at their inner ends with said air inlet and discharging peripherally, and means including an intermediate annular disk extending radially only along the intermediate side edges of the stepped formations on said blades and defining two separate air delivery passages opening respectively from opposite peripheral side portions of said radial passages to provide separate air supplies.

5. A rotary fan blower comprising, in combination, a drive shaft, a disk fixed for rotation with said shaft, a single set of generally longitudinally and radially extending spaced impeller blades fixed to said disk for rotation with said shaft and substantially aligned peripherally about said shaft, the outer end of each blade being stepped longitudinally to provide one side portion with a relatively small external circle of revolution and the other side portion with a. relatively large external circle of revolution, a radially disposed disk rigidly connected along the short side edges of said blades, an axial air inlet in one of said disks opening to the inner ends of the spaces between said blades, and an annular disk disposed intermediately of the first mentioned disks and secured along the free side edges of the intermediate stepped portions of said blades, said last mentioned disk extending inwardly only to the periphery of said small circle of revolution, said blades and said disks defining generally radial passages communicating at their inner ends with said air inlet, each of said passages discharging from the stepped portions of said blades at different peripheral circles of revolution.

WILLIAM O. BEHRENS.

Images