US2912159A

US2912159A - Fans

Info

Publication number: US2912159A
Application number: US572527A
Authority: US
Inventors: Karl M Ganger; William H Wentling
Original assignee: Lau Blower Co
Current assignee: Lau Blower Co
Priority date: 1956-03-19
Filing date: 1956-03-19
Publication date: 1959-11-10
Anticipated expiration: 1976-11-10

Description

Nov. 10, 1959 K. M. GANGER EI'AL 2,912,159

FANS

Filed March 19, 1956 2 Sheets-Sheet 1 FIG-1 4 35 32 V FIG-3 9 83 I 0 1 0 A 2o 51 M FIG -4 16 INVENTORS KARL M.GANGER a 15 BY WIILLIAM awaunms ATTORNEYS Nov. 10, 1959 K. M. GANGER ETAL 2,912,159

FANS

Filed March 19, 1956 2 Sheets-Sheet 2 FIG-6 FIG-5 IN V EN TORS KARL M. SANGER a BY WILLIAM H.WENTLING 9 v' QM y? ATTORNEYS FANS Karl M. Ganger and William H. Wentling, Dayton, Ohio, assignors to The Lau Blower Company, Dayton, Ohio, a corporation' of Ohio Application March 19, 1956, Serial No. 572,527 '5 Claims. Cl. 230-259 This invention relates to fans.

The invention has special relation to fans of the portable type suitable for use in the home and other buildings for purposes of ventilation and circulation of air. For example, the fans. of the invention are especially suited for temporary mounting in a window to serve either for exhausting air from the room or for drawing cool outside air into the room.

It is a primary object of the invention to provide a ventilating fan which incorporates a reversible drive motor to make possible reversal of the air flow from the fan without changing its physical position, and which also incorporates blades of special configuration to give eflicient operation in both directions of rotation and to permit effective cooling of the drive motor in both direc tions of rotation.

An additional object of the invention is to provide a fan blade especially adapted for use in a reversible fan togive efiicient operation in both directions of rotation of the blade assembly and which includes edge portions curved in opposite directions to serve alternatively as leading andtrailing edges and also to promote a cooling flow of air in close proximity to the drive motor in both directions of rotation of the fan.

A further object of the invention is to provide a fan blade as outlined above wherein the curved portions of the blade are provided with integral ribs or beads extending perpendicularly to the axes of curvature thereof to stiffen the curved blade portions for maintaining the curved configurations thereof.

It is also an object of the invention to provide a ventilating fan which incorporates a thermostatic switch for turning the fan motor on and off at predetermined high and low temperatures respectively, and which also incorporates a signal effective to give continuous indication of the open and closed positions of the main control switch of the fan independently of the position of the thermostatic switch.

Additional objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings- Fig. 1 is a view in front elevation showing a fan constructed in accordance with the invention;

Fig. 2 is an enlarged fragmentary sectionon the line 22 of Fig. 1;

Fig. 3 is a wiring diagram for the fan of Fig. 1;

Fig. 4 is an enlarged detail section on the line 4-4 of Fig. 1;

Fig. 5 is an enlarged view in vertical section through the casing of the fan of Fig. 1 as indicated by the line 5-5 of Fig. 1;

Fig. 6 is a detail view in front elevation of the blade assembly of the fan of Figs. 1 and 4;

Fig. 7 is an outer end elevation of one of the fan blades of Fig. 6;

Fig. 8 is a detail elevational view illustrating one of the blades in Figs. 6 and 7; and

2 Fig. 9 is an enlarged fragmentary section onthe line 9,-9 of Fig. 8.

Referring to the drawings, which illustrate a preferred embodiment of the invention, the casing 10 is of gen erally rectangular annular shape. A panel -11 of generally channeled configuration is mounted within. the casing 10 along one of theshorter sides and at the front thereof, anda similar panel 12 is mounted at the back of the casing. These panels are proportioned to cover a fraction ofthe casing such that the remaining open area is approximately square, and the venturi panel 13 is mounted in the casing with the opening therethrough centered on the open part of the casing. A bracing strip 14 is connected between the

panels

11 and 12 and the venturi panel 13 as shown in Fig. 2 to provide a rigid assembly.

A carrying handle 15 is mounted at the top of the casing in centered relation along the longer side in conjunction with a decorative and stiffening cap 16. The handle 15.normally rests in a retracted position as shown in Fig. '4, which is provided for by the bolts 17 which slide in rubber grommets 18. When it is desired to use the handle to lift the fan, the handleis raised to the dotted position shown in Fig. 4.

A drive motor 20 is mounted within the casing 10 in centered relation with the opening through the venturi panel 13 by means of a bracket 21 which extends vertically between the top and bottom of the casing. The motor shaft 22 projects from the front of the motor and supports the blade assembly which comprises a spider 23 secured to the shaft by a hub 24 and set screw and carrying three blades 25. A grill 26 is shown as mounted by brackets 27 on the front of the casing to guard the front of the fan, and a similar grill maybe mounted at the back of the casing.

The panel 11 provides a mounting for the several controls for the fan which are shown in the wiring diagram in Fig. 3. The power leads L-1 and L-2 are contained within a conventional electric 'cord.30. The main control switch 31 is shown as having an Off and three On positions to provide three selective speeds for the fan. A thermostatic switch 32 is connected in series with con: trol switch 31 and the motor, and this thermostatic switch is designed to close the circuit between the main switch 31 and the motor at a predetermined high tem' perature for starting the fan and to open at a predeter: mined low temperature in order to shut off the fan.

In use with this arrangement as described up to this point, the fan may be mounted in a window and turned on during a summer night for the purpose of cooling a bedroom. If the room temperature drops sufficiently to permit the fan to be turned off without interfering with the comfort of the sleeper, the thermostatic switch accomplishes this result. If the temperature should subsequently rise, the fan would then again be turned on, and so forth. However, it is possible that the fan will not be running in the morning when the user rises and that the user may close the window without remembering to open the main switch 31. Then later in the morning when the temperature in the room rises, the thermostatic switch would, again start the fan, and if the window were closed, or if the occupants were not in the building, there would be no reason for operating the fan.

The present invention includes a provision directed to preventing-the undesirable result just discussed by estab-' lishing a continuous signal of the position of the control switch 31. This signal is shown as a light 33 mountedat the top of the panel 11 and connected in series with the main switch 31'but in parallel wtih the motor and thermo staticswi'tch 32 so that the light 33 will be energized whenever the switch 31 is closed irrespective of the position of the thermostatic switch 32. Therefore, in the instance described in the preceding paragraph, on rising in the morning the user of the fan will see that the light 33 is lighted and will therefore be reminded to turn the main switch 31 to its Off position before leaving the fan for the day.

In addition to the main and thermostatic switches, the motor 20 is provided with a reversing switch 35 which is also mounted on the panel 11. Satisfactory results have been obtained in use with the motor 20 being of the shaded pole type provided with alternatively usable shading coils adapted to be selectively open circuited by the switch 35 as indicated in Fig. 3, and also with the motor 20 of the permanent split capacitor type provided with the same type of reversing switch 35. This arrangement provides for reversal of the direction of flow of air from the fan without changing the position of the casing or changing the position of the fan itself within the casing.

The fan blades 25 are of special configuration and characteristics which provide several practical advantages. Referring particularly to Figs. 6-9, the main central area 40 of each blade 25 is essentially flat, and it extends from the inner edge of the blade and includes a major portion of the outer edge of the blade. This'central blade area 40 is mounted on the spider 23 in inclined relation with a radial plane through motor shaft 22 such that when the direction of rotation of the blade assembly is clockwise as viewed in Figs. 1 and 6, the resulting air flow will be toward the front of the fan. The portion 41 of each blade will therefore be the leading edge portion, and it is cylindrically curved with respect to the portion 40 along the line 42 and toward the back of the fan. The similar portion 44 along the opposite edge of the blade is curved forwardly along the line 43. Both of these

curved portions

41 and 44 also incorporate integrally formed ribs or beads which extend out to the edge of the blade from the flat portion 40 and substantially perpendicularly to the

lines

42 and 43 respectively.

As shown in Figs. 6 and 9, the inner edge of each 7 blade 25 includes a middle section 46 of substantial extent which is arcuately curved to be substantially concentric with the axis of the motor shaft 22 in the mounted position of the blade. In addition, the

inner edge sections

47 and 48 of each blade are curved in the opposite direction from the section 46 to provide lobe or corner-like portions on the blade in the areas thereof nearest to the motor 20. These lobe portions form the major areas of the

respective side portions

41 and 44, and they have important actions in the operation of the fan.

Thus when the fan is rotating in clockwise direction as viewed in Figs. 1 and 6, the surface speed of the blade is at a maximum at its radially outer edge and a minimum in the portion closest to the spider 23. However, the largest proportion of the curved blade portion 44 is adjacent the spider 23, as is apparent from Fig. 6, and the concave face of the portion 44 is opposed to the flow of air across the front surface of the blade. The result of this combination of factors is that the portion 44 is in effect of materially increased pitch as compared with the central area 40 of the blade, and this compensates for the decreased relative surface speed of the portion 44 and enables it to propel more nearly the same volume of air per unit area thereof as the flat outer portion of the blade.

In addition to the increased total volumetric flow of air provided by this blade construction, it is especially important that the curved portion 44 produces an axial air flow in close proximity to the motor 20 for maintained cooling action on the motor. This effect is also contributed to by the blade portion 41, since it acts, as a leading edge of increased effective pitch which augments the total air delivery of the fan.

Similar operating conditions obtain when the drive motor is reversed to rotate the blade assembly in the oppo site direction. The curved portion 41 then becomes the trailing edge and operates in the same manner as described for the portion 44' to produce a cooling flow of air in close proximity to the motor, and the portion 44 similarly becomes a leading edge of increased pitch to supplement the action of the trailing edge portion 41. Theoretically, if the blade were perfectly symmetrical, with the

portions

41 and 44 of the same relative areas and effective pitch, identical flow conditions would exist for either direction of rotation of the motor, but this would require the overall depth of the fan casing to be greater than with the illustrated arrangement, and the configuration of the blade illustrated in Fig. 8 has given satisfactory results.

The construction and mode of operation of the blade assembly of the invention are also of importance in connection with the reversing of the drive motor during operation of the fan. More particularly, with either of the above types of reversible motor, it is necessary that the total load on the motor approach the capacity of the motor if reversal is to take place. This result is obtained in accordance with the invention by the action of the trailing edge portions of the blades, since in addition to producing a cooling air flow close to the motor, they tend to create a braking force on the blade assembly such that if the reversing switch 35 is shifted during operation of the fan, the blade assembly will immediately slow down and ultimately start rotation in the opposite direction. In contrast, if the trailing edge of the blade were flat or curved in the same direction as the leading edge, the load on the motor would in all probability not be sufficient to accomplish reversal during operation, and instead the motor would tend to continue to rotate in the same direc tion in spite of shifting of the reversing switch.

Because of the important contribution of the edge portions of the blade to the mode of operation of the fan as a whole, it is desirable that they be constructed with the maximum uniformity compatible with practicability. This result is materially aided by the ribs or beads 45. In particular, these beads have a substantial stiffening effect on the blade which maintain the blade in the desired curved configuration. Thus since different batches of sheet metal have a tendency to vary in resiliency, if the curved edge portions were formed without the beads, there would be a correspondingly varied tendency for the blades to spring back after their curved edge portions have been formed therein, and this would create non-uniformity. The ribs 45, however, which extend transversely of the radius of curvature of the

respective portions

41 and 44, resist the tendency of the sheet metal to change shape after forming and thus make it possible to establish uniform predetermined curvature in all blades which will accurately represent the curvature of the dies by which the forming operation is carried out.

Cross reference is made to our application Serial No. 775,278 filed November 20, 1958 as a division of this application.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

l. In combination, a reversible electric motor having a drive shaft, a fan blade assembly mounted on said shaft and including a plurality of blades, each of said blades comprising a main generally flat center portion extending from the inner edge of said blade and including at least a major portion of the outer edge thereof,

' said inner edge of said blade including an extended middle section curved substantially concentrically with respect to said axis and opposite end sections curved in opposite directions to provide a pair of lobe portions each including portions of said inner edge and one side edge of said blade, side portions of substantial axial pitch on both sides of said blade extending in opposite portions forming major areas of the respective said side portions to provide leading and trailing edge portions on said blade of substantial area such that in either direction of movement thereof one of said edge portions Will form a trailing edge portion of increased pitch with respect to said center portion causing an axially directed airflow in close proximity to said axis for cooling said motor.

2. In combination, a reversible electric motor having a drive shaft, a fan blade assembly mounted on said shaft and including a plurality of blades, each of said blades comprising a main generally flat center portion extending from the inner edge of said blade and including at least a major portion of the outer edge thereof, side portions of substantial axial pitch on both sides of said blade extending in opposite directions from said fiat center portion, the outer edges of said side portions each including portions of said inner edge and one side edge of said blade, said inner edge being curved ooaxially about said axis, and each of said side portions having the major area thereof located on the radially inner portion of said blade so that rotation of said blade in either direction will cause an axially directedair flow in close proximity to said axis for cooling said motor.

3. In combination, a reversible electric motor having a drive shaft, a fan blade assembly mounted on said shaft and including a plurality of blades, each of said blades comprising a main generally flat center portion extending from the inner edge of said blade and including at least a major portion of the outer edge thereof, said inner edge being curved substantially concentrically about said axis, side portions of substantial axial pitch integrally formed on both sides of said blade and extending in op posite directions from the plane of said center portion, the outer edges of said side portions each including portions of said inner edge and one side edge of said blade to define a pair of lobe portions located on the radially inner portion of said blade so that rotation of said blade in either direction will cause an axially directed air flow in close proximity to the axis for cooling said motor, and an integral bead formed on each of said side portions and extending substantially perpendicularly to the axis of curvature thereof from said center portion of said blade to stiffen said side portions and said lobes for maintaining the curved configuration thereof.

4. A fan blade of the character described comprising a main generally flat center portion extending from the inner edge thereof and including at least a major portion of the outer edge thereof, side portions of substantial axial pitch on both sides of said blade extending in opposite directions from the plane of said center portion, the outer edges of said side portions each including portions of said inner edge and one side edge of said blade, and each of said side portions having the major area thereof located in the radially inner portion of said blade.

5. A fan blade of the character described comprising a main generally flat center portion extending from the inner edge of said blade and including at least a major portion of the outer edge thereof, said inner edge of said blade including an extended middle section of concave curvature and opposite end portions of convex curvature providing a pair of lobe portions each including portions of said inner edge and one side edge of said blade, side portions of substantial axial pitch on both sides of said blade extending in opposite directions from said blade cetner portion, and said lobe portions forming major areas of the respective said side portions.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2 9l2 l59 November l0 1959 Karl M. Ganger et a1.

It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 69 for "wtih" read with --g column 4 line 64L and column 5,

lines

10 and 26 after "shaft" and before the comma each occurrence insert adapted to rotate about a predetermined axis coinciding with the axis of said motor same column 5', line 40, for "the axis." read said axis column 6, line 25 for "cetner" read center Signed and sealed this 13th day of September 1960.

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents