US1887873A - Centrifugal fan - Google Patents

Description

Nov. l5, `1.932. H. F. HAGEN CENTRIFUGAL FAN Filed Feb. '3. 1930 I /N ENTOR 7J MWM Malay A from/E Patented Nov. 15, 1932 UNITED STATES PATENT OFFICE HAROLD F. HAGEN, OF DEDHAM, MASSACHUSETTS, ASSIGNOR TO IB. F. 'STURTEVANT COMPANY, lOF HYDE PARK, MASSACHUSETTS, A CQBPORATION OF MASSACHUSETTS CENTRIFUGAL FAN Application tiled February 3, 1930. Serial No. 425,433.

The present invention relates to centrifugal fans. Y

The object of the present invention is to provide a simple and easily operatedcentrifugal fan, theoutput of which may be etliciently controlled independently of the speed.

In my copending application, Serial No. 210,666, filed August 4, 1927, I have disclosed a method and apparatus whereby the output of a centrifugal fan may be controlled without the necessity of employing the common but expensive method of speed control or the ineiiicient method of throttling. Briefly, the principle ofthe invention of said application consists in output regulation by imparting to fthe entering fluid a variable and controllable spin velocity in the direction of rotation of prior invention includes a plurality of si-Y multaneously adjustable vanes to direct the entering fluid into the rotor `at a variable angle. A

The present invention, while operating on the principle of varying output control of spin velocity, conslsts .of a modl cation of the prior invention, principally with a vlew toward economy and simplicity of construction. A

In its simplest form, it comprises an inlet chamber which by its shape has an inherent tendency to introduce a spin into the Huid, together with deilecting means adjacent the entrance opening of the chamber, thereby to control the direction of the entering currents of fluid and thus to vary the spin component of velocity. Such deflecting means does not constitute a throttling means because although the air passage may be reduced in cross-sectional area, the volume of fluid passing is itself so far reduced by the limitation of the output of the fan, due to increased spin of the air, that the objectionable features of throttling are entirely avoided.

In the accompanyin drawing illustratin 'what is now considere the (preferred form o the invention, Fig. 1 is a si e elevation of an induced draft fanwith the output controlling means in position for maximum output; Fig. 2 is an end elevation of the fan shown in Fig. 1;` -and Fig. 3 is a view similar to Fig. l showing the output controlling means in position for reduced output.

The illustrated embodiment of the invention comprises a fan having a rotor 4, inlet boxes 6 and 8v on opposite sides of the rotor and an outlet box or scroll 10. The inlet boxes 6 and 8 being of identical construction, a description of one only will sufiice. The

`fan, is curved away from the eye for a, short distance, The wall 18 is of circular contour havlng its center directly below the axis of Athe rotor and curving 1n the same general direction as wall 16, but more sharply. The walls 16 and 18 meet the scroll portion ofthe inlet box in a constricted throat 20.

In order to control and vary the ma itude of the spin velocity ofthe fluid a mitted to the rotor, the entrance chamber 14 is provided with a pivoted gate or def-lector 22 which is in the sha e of a sector having a curved plate 24 coniibrming to the inside of the wall'18 and also provided with a reversed lip 26 which conforms to the throat portion ofthe inlet box when the gate is completely open as shown in Fig. 1. The deflector. is also formed with side plates 28 which are secured to a rock shaft 29. The defiector is counter-balanced by a weight 30 and is adapted to be moved to any desired position by a link 32 attached to the rock shaft. By

means of the lever 32, the deflector may be moved from full open position, as shown in Fig. 1, through an intermediate position, as shown vin Fi 3, to fully closed position wherein lthe 11p 26 engages with the wall 16V of the entrance chamber.

upper part of the inlet box 6 is of the usual i scroll formation, as indicated at 11. The

By variation of the positionof the deiector 18, the magnitude of the spin velocity of the fluid entering the rotormay be conveniently adjusted. When the deiector is in the posi- -tion shown in Fig. 1, the air enters the inlet side wall of the scroll before entering the eye. The amount of rotation which the fluid thus assumes in this position of the deflector is, however, too smallto cause any serious reduction in fan capacity. In fact, this slight rotation is advantageous in that it causes the fluid to distribute itself uniforml around the eye of the fan. At the open pos`1- tion of the deilector, therefore, the fluid en ters the eye along nearly radial lines, and with minimum spin, so that maximum output is obtained.

When the deflector is adjusted, say to the position of Fig. 3, the entering fluid follows the eneral direction of the arrows and being initially confined to the space immediately adjacent to the outside wall of the scroll, tends to circulate more completely around the casing and to assume a much greater angle of entrance into the eye of the fan. In fact, the iuid may spin more than one complete revolution around the casing before passing into the fan. In other words, the fluid, instead of passing into the eye of the fan along nearl radial lines, now assumes a directionwhic deviates from the radial and approaches the tangential. The spin velocity in the d irectionv of rotation is thereby increased and the fan is able to do only a decreased amount of work on the fluid. As the deilector is moved farther toward the left in Fig. 3, the component of spin velocity increases and the work done by the fan upon the air is further decreased. Thus, the fan may operate at constant speed, as with an induction motor drive, without the necessity for employing complicated speed control or ineiiicient throttling devices. It will be noted, that. although the deflector 18, as it is moved from the position of Fig. 1 to that of Fig. 3, progressively reduces the area or opening of the throat 20, nevertheless no appreciable throttling occurs. The construction is such that as the deflector is moved to the left of Fig. 3, .the spin velocity is so greatly increased that it becomes the predominant factor in determining the Work done by the fan and reduces the volume of air to such an extent that it may freely flow through the reduced area ofthe throat without producing any throttling eifect or appreciable lloss in efficiency. A

The fan described above may be employed for either forced draft or induced draft` or in fact, for any purpose for which centrifugal fans are adapted. For forced draft, the entrance chamber 14 may open directly to the admission of fluid to the eye, whereby the output of the fan may be controlled.

2. A fan comprising an inlet box including a scroll having an eccentric eye and an -entrance chamber connected with the scroll and having an adjustable curved fluid directing wall to direct the luid to a greater or lessf extent into the outer peripheral portion of4 the scroll, and means for adjusting said wall to vary the spin velocity of fluid admitted to the rotor.

3. A fan comprising a rotor, an inlet scroll having an eye, an entrance chamber connected with the inlet scroll, the scroll being shaped to cause the fluid to assume a spin velocity prior to the entrance into the eye, and means for varying the spin velocity attained in the scroll including a deflector to vary the direction of delivery of the fluid to the scroll .from the entrance chamber.

1. A fan comprising an inlet scroll, an entrance chamber therefor having a curved fluid directing wall merging with the scroll,

the scroll having an eccentric eye at a dis' tance from the fluid directing wall and nearer the opposite wall of the scroll, a rotor, and a deflector in the entrance chamber adapted to be moved toward the fluid directing wall to direct the fluid entering the scroll to a greater or less extent into the outer periphe of the scroll to increase the spin velocity an thereby'to decrease the output of the fan.

5. A fan comprising an unobstructed inlet scroll having an eye eccentrically positioned therein, an entrance chamber through which the fluid passes prior to entrance into the scroll, and means exteriorly of the scroll for varying the direction of delivery of air from the chamber to the scroll to control the output of the fan.

6. A fan comprising an inlet scroll, an entrance chamber having a. curved wall for directing the delivery of air to the scroll, and a curved deflector adjacent said wall and adjustable to form a variable extension thereof to control the direction of the air entering the scroll from the chamber.

7. A fan comprising an inlet chamber having an eye therein, an entrance chamber opening into the inlet chamber, the inletchamber having a curved wall to rotatevthe fluid in its passage toward the eye, and movabley means for varying the opening of the entrance chamber into .the inlet chamber to regifilate the spin ofthe air and output of the 8. A fan comprising an inlet chamber having an eye therein, the inlet chamber having a curved Wall to rotate the fluid in its assage toward thee e, an entrance chamber aving an opening into the inlet`chamber for delivering air from the former to the latter and eccentrically of the eye, and means bem tween the entrance and the inlet chamber for determining the extent of eccentricity of such delivery.

9. A ian comprisi a rotor, an inlet scroll having an eccentric eye leadin to the u. rotor and an entrance opening where om the fluid circulates about the scroll to attain a spin component of velocity rior to passing through the eye, and adjusta le means at the having.- an entrancev opening to admit the iuidinto the chambertangentially of the eye to cause the fluid to circulate about thel c tained by the fluid in circulating about the` chamber to the eye.

In testimony'whereof I have signed my name to this specification. v

` HAROLD F. HAGEN.

entrance openingi for vail'ying the spin n velocity attained in the scr 10. A fan cromprising a rotor, an inlet Y scroll having an eccentric eye leading to -the rotor and an entrance opening wherefrom the fluid circulates about the scroll to attain Si a spin component of velocity prior to passing through the eye, and adjustable means at the entrance opening for variabl directing the fluid toward the outer wall o the scroll.

11. A fan comprising 'an inlet scroll having an eccentric eye, a rotor, an entrance 'chamber connected with thescroll and having curved walls to direct iiuid toward the outer peripheryof` the scroll, and an adjustable deilector to vary the extent of fluid direction to'ward the outer periphery of the scroll to vary the s in velocity assumed by the fluid in passing about the scroll.

12. A fan comprising a. rotor, -an inlet chamber having a. curved outer wall and an eye-leadingto the rotor, the chamber hav-- 40 ing an entrance opening to admit the luidv into the chamber tangentiall of the eye to cause the fluid to circulate a ut the chamber and thereby to attaina spin com nent of velocity prior to passing through t e eye, and adjustable means for directing theiluid to a greater or less extent into the outer peripheral portion of the inlet chamber to adjust the s in veloci of the fluid.

13. A' an comprising a rotor, an inlet chamber having a curved outer wall and an eye leading to the `rotor, the chamber having an entrance opening to admit the fluid into the chamber tangentiall of the e e to cause the fluid to circulate a ut the c amber and thereby to attain' a spin component of velocity prior to passin through the eye,

and a deflector for initi y directing the fluid to a ater or less extent into'the outer peripherallle vary thgspin' velocity attained by the fluid in circulating about the chamber.

14. A fan comprising a rotor, an inlet chamber having a curved outer wall and g5 an eye leading to the rotor, theA chamber portion ofthe inlet chamber to .isc

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