US2475910A

US2475910A - Electrically heated fan-heater

Info

Publication number: US2475910A
Application number: US610279A
Authority: US
Inventors: Morrison Montford
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-11-27
Filing date: 1945-08-11
Publication date: 1949-07-12
Anticipated expiration: 1966-07-12

Description

July 12, 1949. M. MORRISON 2,475,910

ELECTRICALLY HEATED FAN-HEATER Original Filed Nov. 27, 1943 INVENTQR Patented July 12, 1949 UNITED STATES PATENT. OFFICE '7 Claims. 1. The present invention relates to ventilating and heatihgart, .relatesin .particular to such an by electrical means, .andrelates specifically to elec-. trical heating unitsprovidedwith electric fans.--

This. application is .a division of application SerialflNo'. 511,957,.filed.November..27, 1943,. now.

abandoned.

Among the objects of the inventionrarez-to. provide anelectrically heatedfan-heater which may be used to circulate/cool air in .warmweather and to..circulate.-warm.airin cool...weather; to provide.-

in .an 1 electrically. heated. fan-heater. .a structure which permits optional focusing of theair circulated so that thecirculated air may be-directed...

to a restricted location, or itmay be spread out, bysimple manual adjustmentof the device duringl operation, and 'to. provide, an electrically,

heated fan-heater structure whichis comparatively noiseless in operation so that. it may be used in places .where noise is objectionable, such. as in'ithe presence of. sleeping ,persons, hospital patients and undersimilar conditions.

In the prior .art, .portable electric ventilating fans have been supplied with screw-type air-propellers revolving in free air. .These. screw-type propellers have large windage losses, considerable radialcomponentof air propulsion, and operating inzopen air have the,.property of creating large eddy..currents .in the immediate vicinity of the propeller and confiningra. considerable amount of the .air circulation to the general neighborhood of the fan itself instead ofcirculating all the air about the roomunderventilation.

In addition to the low operatingefliciency of these screw-type. air-propellers, they have a high;

moment of inertia which calls for considerable accelerating torque. to bring the propeller up to operating speed and which torque is not required afternperating speed is. attained. This combina-.

tion .of" useless power requirements necessitates a the absence of them- In addition, the metallic-bladed screw-type airpropeller produces a considerable noise which is.

distasteful. to a large portion of the users of.portable ventilating .electric fans.

In the present invention, a high efiiciency radial.

flow turbine type of. air blower is employed which is known to operateat a high'efficiency and is practically noiseless in operation...

In some embodiments'of this invention a screwtype air-propeller may. be .used in. cooperation with the radial flowrotor, if and when desired.

Further, in .the present invention withsuc-h a type of air-impeller; a :deflecting ,surface. is used 40 larger motor than would have to be employed in.

in which .the column of theair-flow may be con-,.

verged or diverged, as desired under the circum:

stances, .and any. adjustment, between ,conver-- genceof the airrfiow and divergence thereof, may

be. made.manually while the rotor is in operation. Further, the internal air space of such a rotor. ask-employed. in. the present invention, maybe provided .with anelectrical heating coil and thus the present invention may be used to provide cool airin warm.,,weather and .warm air in cool.

weather, at Willi Further and other objectswill be pointedout,

and. apparent in thereading. of the description hereinunder, particularly when takenin connectionwith the drawings in which Fig.1 isan. elevationof an. embodiment of my invention shown partly in section, and Fig. 2 is a fragmentary sec.-

tion oftherotor employed taken along the. line,

A--BI'.

Referring ,toFig, 1,..l is a stand supporting an electric motor 2, having shaft extension 3 onto.

which isfixed a hub 41, carrying with it aradialflow air-impellerrotor ,5.

Referring to. Fig.2, which is .a half section of therotor 5 taken along the line AB, Fig. 1,1ooking east. Fig. 2 is a section of the rotor per se,. without anyof. the .surroundingparts included,-

and is thus illustrated f0r.the sake ofclearness. The rotor 5 is notnecessarily of a novel. structure, inso far as the radial air-flow blades are concernedjbut may be of any suitable conven-.

tional construction having end rings .6 and 'I, Fig. 1,..supportin'g intermediate blades such as 9 and I0, 'Figs.,1 and 2. The shape of the impeller blades of. this rotor may have any suitable form,

but'for simplicity, are illustrated in the figure as'being radial, though they may advantageously have curved impelling surfaces.

Referring to'Fig. 1,. end ring 1 has made in- .tegrally with;it hub 4 and said hub 4 is attached to ring! by means of spokes such as H, l2 and I3,'Fig.,2. These, spokes may be formed into a screw-type air-propeller, if and when, desired: and while a'screw-type propeller of such a small diameteris'not very effective in .producingradial,

air-flow, itdo'es'in effect and fact serve to reduce the resistance of axial air-flow which would otherwise be present if the said spokes were formed 'difie'rently."

End ring fi, Fig. 1, maybe, a complete disk which serves to close the outboard .end of the" rotor. 5, or the. outboard end ofv the rotor 5 maybe of a ring; construction such as. illustrated, and substantiallyclosed by means of a lid l4. Lid l4 may have fixed to it an electrical heating coil indicted by the dotted helices l5, which are so disposed within the rotor 5 that a greater watt dissipation is obtained from the said helices in that part of the rotor space having a greater amount of air intake. In other words, the heating coils are disposed in such a way that the watt dissipation is proportional to the ability of the air currents to remove the heat from the region.

Referring to Fig. 1, an air deflecting surface H5 surrounds the rotor 5. The surface I6 is preferably formed by a surface revolution, being that of a paraboloid or any other suitable surface which has a suitable deflecting surface for the radial air currents from rotor 5. The surface it is supported by shell H which is provided with a hollow cylinder l8 having a plurality of openings such as !9 and 20 to permit the influx of free air, indicated by the flow lines 2| and 22. Flow lines 2| and 22 are indicated as not going through the set of openings l9 and 20, but through a set of openings generally at right angles thereto.

Flow lines 2| and 22 pass through the spokes which are formed into a screw-type air-propeller, thence through the heating coil l5 and from there radially to a zone of the surface-of-revolution l6 from which they are deflected, as indicated by following the lines of flow out into free air. If the surface-of-revolution I6 is formed to be responsive to a focal point located generally about the center of the rotor 5, the direction of the lines of flow into free air will diverge in the general direction of the dotted lines 23, or the sadi lines of flow will form a path generally parallel. in direction to the axis of the deflector, such as indicated. by the flow lines 24, or the direction of flow may be caused to converge the general direction of the dotted lines 25, all according to the relative axial position of the rotor 5 with reference to the focal point of the solid of revolution !5.

It will be appreciated that the

flow lines

23, 24 and 25 referred to, really lie within air-flow cones or cylinders, as the air-flow is a column of air symmetrical about the axis of the rotor and deflector.

Hollow cylinder l8, Fig. 1, is provided with an internally threaded end 26 which screws upon an externally threaded member 21, which said external threaded member forms a part of the motor frame 2.

If the threads of 21 are cut right-handed, then a counter-clockwise rotation of the deflector member ll extends the said member in a westerly direction with reference to the center of rotator 5 and a clockwise rotation of member I! moves the said member in an opposite direction, thus a rotary motion applied to member I'l functions to change the position of the deflector with reference to general location of the effective focal origin of the air-flow from the rotor 5, hence, changes the lines of air-flow to the general direction of 23, 24 or 25, as may be desired.

If warm air is desired instead of cool, the heating coils may be turned on and the heat from the said coils focused into or diverged over the space under heating and ventilation. Having these heating coils in the path of air-flow permits a much larger wattage to be employed in these coils than would be permissible in still air with a simple reflector.

Such a construction has a high efficiency, lowmoment of inertia, both functioning to reduce the size of motor 2, as Well as the attendant cost of operation.

The focusing feature of the deflector serves to localize or spread out the air-flow, eliminating the necessity of costly oscillating accessories common to screw-type propeller-ventilators.

The rotor, bein almost totally enclosed by solid material, makes it extremely diflicult to get into difficulty with extraneous objects coming in contact with the rotor blades, such as so often takes place with a screw-type propeller in a Wire guard.

An electrical heater employing a fan structure having a higher number of small impeller blades for a given number of revolutions per minute, than a fan employing a small number of large blades for the same revolutions per minute, operates more quietly than the latter. The experimental basis for this statement is found in an article by A. Page in The Proceedings of the Royal Society of Great Britain for 1925 entitled, An experimental study of the vibration in the blades and shaft of an airscrew (air-propeller).

The terminology used in this description and in the claims hereunder is employed in conformity with standard practice turbine art.

Having described one embodiment of the invention, the scope thereof is covered in the claims hereunder.

What I claim is:

1. In an electric device for heating free-air space, a driving motor, an air-impeller rotor having a cup-shaped form mounted axially upon an extended shaft of said motor and rotatable therewith, said rotor being positioned to intake air through the end thereof adjacent said motor, a concave air-deflector radially surrounding said rotor, an intake port to admit air to said rotor from behind said deflector and in front of said motor, an electrical heating unit positioned in the cavity of said cup-shaped form, said deflector having its deflecting surface open directly to free-air space and formed to deflect heated exhaust air from said rotor into direct stream lines to remotely disposed parts of said space.

2. In an electric device for heating free-air space. a driving motor, an air-impeller rotor having a cup-shaped form mounted axially upon an extended shaft of said motor and rotatable therewith, said rotor being positioned to intake air through the end thereof adjacent said motor, said rotor being provided with a number of impeller vanes in combination with a peripheral velocity thereof causing low operating noise, a concave air-deflector radially surrounding said rotor, an intake port to admit air to said rotor from behind said deflector and in front of said motor. an electrical heating unit positioned in the cavity of said cup-shaped form, said deflector having its deflecting surface open directly to free-air space and formed to deflect heated exhaust air from said rotor into direct stream lines to remotely disposed parts of said space.

3. In an electric device for heating free-air space, a driving motor, an air-impeller rotor having a cup-shaped form mounted axially upon an extended shaft of said motor and rotatable therewith, said rotor being positioned to intake air through the end thereof adjacent said motor, said rotor being provided with a relatively high number of relatively small impeller vanes operating at a peripheral velocity causing relatively low operating noise, a concave air-deflector radially surrounding said rotor, an intake port to admit air to said rotor from behind said deflector and in front of said motor, an electrical heating unit positioned in the cavity of said cup-shaped form, said deflector having its deflecting surface open directly to free-air space and formed to deflect heated exhaust air from said rotor into direct stream lines to remotely disposed parts of said space.

4. In an electric device for heating free-air space, a driving motor, a rotor having air-impeller vanes arranged along a surface of revolution and mounted axially upon an extended shaft of said motor and rotatable therewith, said rotor being formed to intake air through the end thereof adjacent said motor, a concave air-deflector radially surrounding said rotor, an intake air-port to admit air to said rotor from behind said deflector and in front of said motor, an electrical heating unit located in said surface of revolution, said deflector having its deflecting surface open to free-air space, and said vanes formed to exhaust heated air in a direction with respect to said surface to cause said air to assume direct stream lines to remotely disposed parts of said space.

5. In an electric device for heating free-air space, a driving motor, an air-impeller rotor having a cup-shaped form mounted axially upon an extended shaft of said motor with the open end of said cup-shaped form facing said motor, said rotor being rotatable with said shaft, an electrical heating unit located in the cavity of said cupshaped form to heat the rotor intake air, a concave air-deflector radially surrounding said rotor and mounted in moveable axial relation thereto, said deflector having its deflecting surface open directly to free-air space and deflecting exhaust air from said rotor into direct stream lines to remotely disposed parts of said space, the direction of said stream-lines being fixed by said axial relation, and means adapted to change said axial relation to cause a change in the direction of said stream lines.

6. In an electric device for heating free-air space, a driving motor, an air-impeller rotor having a cup-shaped form mounted axially upon an extended shaft of said motor with the open end of said cup-shaped form facing said motor, said rotor being rotatable with said shaft, an electrical heating unit located in the cavity of said cupshaped form to heat the rotor intake air, a concave air-deflector radially surrounding said rotor and mounted in moveable axial relation thereto, said deflector having its deflecting surface open directly to free-air space and formed to converge the directions of exhaust air from said rotor at locations in said space remotely disposed from said deflector, said locations being fixed by said axial relation, and means adapted to change said axial relation to cause a change in the location of the convergence of said directions.

7. In an electrically heated fan-heater, a driving motor, an air-impeller rotor mounted axially upon an extended shaft of said motor, said rotor having a coaxial free space internal of the impeller vanes of said rotor, an electrical heating unit disposed in said space, a concave air-deflector radially surrounding said rotor and formed to deflect radial exhaust air from said rotor away from said motor in a generally axial direction, and an intake air-port to admit air to said rotor from space between said rotor and said motor.

MONTFORD MORRISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,366,519 Carmean et a1. Jan. 25, 1921 1,627,229 Brown May 3, 1927 1,977,357 Slayback Oct. 16, 1934 2,131,484 Ringwald Sept. 27, 1938 2,334,501 Moeller Nov. 16, 1943