US2201437A - Volume control for fans - Google Patents

Volume control for fans Download PDF

Info

Publication number
US2201437A
US2201437A US144892A US14489237A US2201437A US 2201437 A US2201437 A US 2201437A US 144892 A US144892 A US 144892A US 14489237 A US14489237 A US 14489237A US 2201437 A US2201437 A US 2201437A
Authority
US
United States
Prior art keywords
fan
dampers
casing
rotor
inlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US144892A
Inventor
Jr Murray S Kice
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AMERICAN BLOWER Corp
Original Assignee
AMERICAN BLOWER CORP
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AMERICAN BLOWER CORP filed Critical AMERICAN BLOWER CORP
Priority to US144892A priority Critical patent/US2201437A/en
Application granted granted Critical
Publication of US2201437A publication Critical patent/US2201437A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/40Casings; Connections of working fluid
    • F04D29/42Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/44Fluid-guiding means, e.g. diffusers
    • F04D29/46Fluid-guiding means, e.g. diffusers adjustable
    • F04D29/462Fluid-guiding means, e.g. diffusers adjustable especially adapted for elastic fluid pumps
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/40Casings; Connections of working fluid
    • F04D29/42Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/4206Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps
    • F04D29/4213Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps suction ports
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05DINDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2250/00Geometry
    • F05D2250/50Inlet or outlet
    • F05D2250/51Inlet

Definitions

  • My invention relates to fans and in particular to the control of the volume of air delivered by the fan.
  • Figure 1 is a vertical section on the line
  • Figure 2 is a transverse section on the line '2-2 of Figure 1.
  • the inlet control dampers are disposed in horizontal line across the inlet opening of the air inlet casing, with respect to which the fan rotor is concentrically disposed.
  • Figure 3 is a view similar to Figure 1 of a modification with the dampers arranged. in a line remote from the entrance of'the air inlet casing and the independent dampers and at difl'erent distances from the fan rotor which is v eccentrically located with respect to the axis of the inlet air casing. This figure is on the line 33 of Figure 4.
  • Figure 4 is a section on the line 4-4 looking of Figure 8.
  • the dampers are diagonally disposed with respect to a concentrically located rotor and 45 therefore are located at varying distances from said rotor.
  • Figure 8 is a section on the line 8-8 of Figure '7.
  • Figure 9 is a view of a fourth modification which 50 is similar tothat shown in Figure '7, except that the rotor is eccentrically located with respect to the air inlet casing.
  • Figure 9 is a section of the line 99 of Figure 10. I
  • Figure 10 is a section on the line I 0l0 of 55 Figure 9.
  • Figure 11 is a view of a fifth modification which is similar to that shown in Figure 9, except that the line on which the dampers are located is an angular line, a portion of the dampers being 10'- cated on a diagonal portion of that line, and 5 another portion on a horizontal portion of that Figure 11 is a section on the line l!-Il of Figure 12.
  • FIG 12 is a section on the line I2--I2 of Figure 11.
  • l 10 Referring to the drawings in detail, a fan air inlet chamber l is formed by a casing having a rounded end wall 2 and parallel side walls 3 forming an air inlet opening 4 in conjunction with a covering plate 5 and the side wall 6 of a 15 fan casing.
  • the side wall 6 is provided with an air inlet passageway I which extends from the exit of the air inlet casing chamber I 'to the rotor of the fan.
  • the rotor of the fan is provided with 20 a supporting central plate or spider 8, fan blades 9 and their shrouds ID, or without shrouds.
  • This passageway 26 is Venturi shaped, but not necessarily so.
  • the inlet passageway 1 is constituted of a casing which extends from the base of the shrouds l0 into the interior. of the inlet chamber and is provided with a peripherally 30 flared edge.
  • the annular space left between the peripheral edge of said casing and the inner side wall 6 of the inlet. chamber l is closed by a narrow cylindrical strip of metal.
  • volute fan casing l 2 Surrounding the rotor is the volute fan casing l 2, having discharge opening l3. There are similar air inlet chambers and casings and air inlet passageways 1 on both sides of the fan casing of a double inlet fan, or one air inlet chamber and casing and inlet passage on one side of a single inlet fan.
  • dampers 68 are denominated l4 and are mounted upon axles ii.
  • the axle for the fan l6 supports the fan rotor concentrically with the center of the air inlet casing.
  • the dampers in these two views havev their axes arranged on a straight line adjacent the mouth of the air inletcasing.
  • dampers are arranged on an arc concentrically with the rotor
  • the efliciency of the fan can be maintained more nearly constant through adjusting the preliminary whirl of the air in harmony with the variation in volume of the air.
  • the difiiculty with varying the volume of the air has been a variation in the efiiciencyof the fan which I now improve by being able to vary the volume and at the same time, regulate the preliminary whirl of the air.
  • the volume and preliminary whirl can be controlled, and the preliminary whirl can be regulated, that is, increased and decreased, by some Concerning the positions of these' It will be understood that I desire to com prehend within my invention such modifications as maybe clearly embraced within the claims and scope of my invention.
  • a fan comprising a fan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet box mounted with respect to said fan casing so as to communicate therewith through said opening and through the side of said inlet box, said inlet box comprising an arcuate end and longitudinally extending walls to form an open end into said box, and a plurality of independently operable transversely disposed dampers arranged across said inlet box, whereby the amount of whirl of gas leaving said box and the volume of gas entering the box may be controlled, said dampers being arranged with their rotating axes parallel to the axis of the fan rotor, said damper axes being arranged in the same plane.
  • a fan comprising a fan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet box mounted with respect to said fan casing so as to communicate therewith through said opening, and a plurality of independently operable transversely disposed dampers arranged across said inlet box whereby the amount of whirl of gas leaving said box and the volume of gas entering the box may be controlled, said fan casing projecting into the inlet box and provided with a flared edge whereby the gas passing through the inlet box into the rotor has its direction changed without any disturbances of the whirl of the gas, said dampers being arranged with their rotating axes parallel to the axis of the fan rotor and said damper axes being arranged in the same plane.
  • a fan comprising a fan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet box mounted with respect to said fan casing so as-to communicate therewith through said opening, and a plurality of independently operable transversely disposed dampers constituting at .least three arranged across said inlet box, whereby the amount of whirl of gas leaving said box and volume of gas entering the box may be controlled, said tan casing projecting into the inlet box and provided with a flared edge whereby the gas passing through the inlet box into the rotor has its direction changed without any disturbance of the whirl of the gas, said dampers being arranged with their rotating axes parallel to the axis of the fan rotor and said damper axes being arranged in the same plane.
  • a fan comprising a fan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet boxmounted with respect to said fan casing so as to communicate therewith through said opening, and means including a plurality of transversely disposed dampers across said inlet box for controlling the amount of whirl of gas leaving said box and the volume of gas entering the box, said dampers being arranged with their rotating axes parallel to the axis of the fan rotor and the said axes bein arranged inthe same plane, and said dampers being constructed and arranged so that when closed they will practically out off the in-flow of 5.
  • a fan comprising a tan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet box mounted with respect to said fan casing so as to communicate therewith through 'said opening, and a plurality of transversely disposed dampers arranged across said inlet box whereby the amount of whirl of gas leaving said box and the volume of gas entering the box may be controlled, said Ian casin projecting into the inlet box and provided with a flared edge whereby the gas passing through the inlet box into the rotor has its direction changed without-any disturbance of the whir1 of the gas, said dampers being arranged with their rotating axes parallel to'the axis of the fan rotor and said'damper axes being arranged in the same plane, said dampers being constructed and arranged so that when closed they will practically cut off the in-fiow of air.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Description

May 21, 1940. M. 's. KICE. JR 3 3 VOLUME CONTROL FOR FANS Filed May 26. 1937 3 Sheets-Sheet 1 INVENTOR MURRAY 8. M05, JR.
May v21, 1940. M. s. KICE. JR 2,201,437 I VOLUME CONTROL FOR mus Filed May 26, 1937 I 3 Sheets-Sheet 2 /N VE/V TOR MURRAY 6. M05, J/P. BY
ATTORNEYS y 1940. M. s. KlCE,-JR I 2,201,437.
VOLUME CONTROL FOR FANS Filed May 26, 1937 3 Sheets-Sheet 3 "was/r01; NQRRAY 61/00:, JR. BY
ATTORNEYS Patented May 21, 1940 UNITED STATES 2,201,431 voLUME ooN'rnoL FOR FANS tMurray S. Kice, Jr., Detroit, Mich., assignor to American Blower Corporation, Detroit, Mich, a corporation of Delaware Application Maize, 1937, Serial No. 144,892
Claims.
My invention relates to fans and in particular to the control of the volume of air delivered by the fan.
In particular, it'is my' object to provide a plu- 6 rality of independent adjustable dampers in the inlet of the fan casing, and so distributed with respect to the position of the fan rotor and the inlet casing so that the dampers regulate the efliciency of the fan in conjunction with the varying volume as controlled by the dampers, utilizing the dampers for regulating the preliminary whirl of the air'in the inlet casing before it enters the rotor of the fan. 7
Referring to the drawings in detail:
Figure 1 is a vertical section on the line |-l of Figure 2. 1
Figure 2 is a transverse section on the line '2-2 of Figure 1. In this view and the preceding view, the inlet control dampers are disposed in horizontal line across the inlet opening of the air inlet casing, with respect to which the fan rotor is concentrically disposed.
Figure 3 is a view similar to Figure 1 of a modification with the dampers arranged. in a line remote from the entrance of'the air inlet casing and the independent dampers and at difl'erent distances from the fan rotor which is v eccentrically located with respect to the axis of the inlet air casing. This figure is on the line 33 of Figure 4.
' Figure 4 is a section on the line 4-4 looking of Figure 8. In the construction shown in this View, the dampers are diagonally disposed with respect to a concentrically located rotor and 45 therefore are located at varying distances from said rotor.
Figure 8 is a section on the line 8-8 of Figure '7.
Figure 9 is a view of a fourth modification which 50 is similar tothat shown in Figure '7, except that the rotor is eccentrically located with respect to the air inlet casing. Figure 9 is a section of the line 99 of Figure 10. I
Figure 10 is a section on the line I 0l0 of 55 Figure 9.
' line.
Figure 11 is a view of a fifth modification which is similar to that shown in Figure 9, except that the line on which the dampers are located is an angular line, a portion of the dampers being 10'- cated on a diagonal portion of that line, and 5 another portion on a horizontal portion of that Figure 11 is a section on the line l!-Il of Figure 12. t
Figure 12 is a section on the line I2--I2 of Figure 11. l 10 Referring to the drawings in detail, a fan air inlet chamber l is formed by a casing having a rounded end wall 2 and parallel side walls 3 forming an air inlet opening 4 in conjunction with a covering plate 5 and the side wall 6 of a 15 fan casing.
The side wall 6 is provided with an air inlet passageway I which extends from the exit of the air inlet casing chamber I 'to the rotor of the fan. The rotor of the fan is provided with 20 a supporting central plate or spider 8, fan blades 9 and their shrouds ID, or without shrouds.
It will be noted that the shrouds ID, if used,
'overlap, but are spaced from similarly spaced ends H of inlet passageway 1. This passageway 26 is Venturi shaped, but not necessarily so.
It will be noted that the inlet passageway 1 is constituted of a casing which extends from the base of the shrouds l0 into the interior. of the inlet chamber and is provided with a peripherally 30 flared edge. The annular space left between the peripheral edge of said casing and the inner side wall 6 of the inlet. chamber l is closed by a narrow cylindrical strip of metal. It has been found that by extending the passageway 1 for a con- 86 siderable distance into the chamber I and providing a flared edge, the air flowing through the inlet opening 4 is readily changed from a radial to an axial direction without the formation of eddies or other conditions which signify inefficient flow.
Surrounding the rotor is the volute fan casing l 2, having discharge opening l3. There are similar air inlet chambers and casings and air inlet passageways 1 on both sides of the fan casing of a double inlet fan, or one air inlet chamber and casing and inlet passage on one side of a single inlet fan.
The volume of the air entering the air inlet casings and the direction of the air is controlled by the setting of the dampers, which are either independently controlled or controlled in harmony with one another and in unison by any desired'mechanism which determines their relative position and angularity. These dampers 68 are denominated l4 and are mounted upon axles ii.
In the construction of Figures 1 and 2, the axle for the fan l6 supports the fan rotor concentrically with the center of the air inlet casing. The dampers in these two views havev their axes arranged on a straight line adjacent the mouth of the air inletcasing.
In the construction of Figures 3 and 4, the construction arrangement is the same except that the fan rotor is located eccentrically of the air inlet casing and the dampers are moved inwardly on a line placed closely adjacent the rotor and relatively remote the entrance of the air inlet casing.
In the construction of Figures 5 and 6, the
dampers are arranged on an arc concentrically with the rotor;
In the construction of Figures 7 and 8 the dampers are arranged on a line diagonal to the axis of the air inlet casing and'are therefore arranged at varied distances with respect to the rotor.
In the construction of Figures 9 and 10 the same alignment of the dampers is maintainedwith the dampers arranged progressively away from the air inlet opening and closer to the fan rotor, except that the rotor is eccentrically located with respect to the longitudinal axis of the air inlet casing, which brings about a difierent relationship of the dampers with respect to the air inlet casing to the rotor.
In the construction of Figures 11 and 12, the construction illustrated in Figures 9 and 10 is somewhat modified, in that a portion of the dampers are arranged on a line transverse to the line of the air inlet casing and a portion on a line diagonal thereto. i
The principle running through these various modifications is this:
By utilizing an air inlet casing which has a curved inner wall and a straight walled inlet passageway with a plurality of volume and direction controlled dampers; and by adjusting. these dampers to vary the volume, the efliciency of the fan can be maintained more nearly constant through adjusting the preliminary whirl of the air in harmony with the variation in volume of the air. Heretofore the difiiculty with varying the volume of the air .has been a variation in the efiiciencyof the fan which I now improve by being able to vary the volume and at the same time, regulate the preliminary whirl of the air.
The position of the dampers in the several views illustrates my invention. By reducing the volume through closing some of the dampers and partially closing others, and using the remainder as air guiding vanes, it is possible to cause the air respect to the air inlet casing, both have ad-.
vantageous features.
By using an angular and progressive displacement of the dampers with respect to the rotor, the volume and preliminary whirl can be controlled, and the preliminary whirl can be regulated, that is, increased and decreased, by some Concerning the positions of these' It will be understood that I desire to com prehend within my invention such modifications as maybe clearly embraced within the claims and scope of my invention.
Having thus fully described my invention, what I claim as new and desire to secure by Letters' Patent is:
1. In combination, a fan comprising a fan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet box mounted with respect to said fan casing so as to communicate therewith through said opening and through the side of said inlet box, said inlet box comprising an arcuate end and longitudinally extending walls to form an open end into said box, and a plurality of independently operable transversely disposed dampers arranged across said inlet box, whereby the amount of whirl of gas leaving said box and the volume of gas entering the box may be controlled, said dampers being arranged with their rotating axes parallel to the axis of the fan rotor, said damper axes being arranged in the same plane.
2. In combination, a fan comprising a fan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet box mounted with respect to said fan casing so as to communicate therewith through said opening, and a plurality of independently operable transversely disposed dampers arranged across said inlet box whereby the amount of whirl of gas leaving said box and the volume of gas entering the box may be controlled, said fan casing projecting into the inlet box and provided with a flared edge whereby the gas passing through the inlet box into the rotor has its direction changed without any disturbances of the whirl of the gas, said dampers being arranged with their rotating axes parallel to the axis of the fan rotor and said damper axes being arranged in the same plane.
3. In combination, a fan comprisinga fan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet box mounted with respect to said fan casing so as-to communicate therewith through said opening, and a plurality of independently operable transversely disposed dampers constituting at .least three arranged across said inlet box, whereby the amount of whirl of gas leaving said box and volume of gas entering the box may be controlled, said tan casing projecting into the inlet box and provided with a flared edge whereby the gas passing through the inlet box into the rotor has its direction changed without any disturbance of the whirl of the gas, said dampers being arranged with their rotating axes parallel to the axis of the fan rotor and said damper axes being arranged in the same plane.
4. In combination, a fan comprising a fan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet boxmounted with respect to said fan casing so as to communicate therewith through said opening, and means including a plurality of transversely disposed dampers across said inlet box for controlling the amount of whirl of gas leaving said box and the volume of gas entering the box, said dampers being arranged with their rotating axes parallel to the axis of the fan rotor and the said axes bein arranged inthe same plane, and said dampers being constructed and arranged so that when closed they will practically out off the in-flow of 5. In combination, a fan comprising a tan casing, a rotor therein, said casing having a side inlet opening adapted to communicate with the interior of said rotor, an inlet box mounted with respect to said fan casing so as to communicate therewith through 'said opening, and a plurality of transversely disposed dampers arranged across said inlet box whereby the amount of whirl of gas leaving said box and the volume of gas entering the box may be controlled, said Ian casin projecting into the inlet box and provided with a flared edge whereby the gas passing through the inlet box into the rotor has its direction changed without-any disturbance of the whir1 of the gas, said dampers being arranged with their rotating axes parallel to'the axis of the fan rotor and said'damper axes being arranged in the same plane, said dampers being constructed and arranged so that when closed they will practically cut off the in-fiow of air.
MURRAY S. KICE, 38..
US144892A 1937-05-26 1937-05-26 Volume control for fans Expired - Lifetime US2201437A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US144892A US2201437A (en) 1937-05-26 1937-05-26 Volume control for fans

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US144892A US2201437A (en) 1937-05-26 1937-05-26 Volume control for fans

Publications (1)

Publication Number Publication Date
US2201437A true US2201437A (en) 1940-05-21

Family

ID=22510608

Family Applications (1)

Application Number Title Priority Date Filing Date
US144892A Expired - Lifetime US2201437A (en) 1937-05-26 1937-05-26 Volume control for fans

Country Status (1)

Country Link
US (1) US2201437A (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2561840A (en) * 1940-04-09 1951-07-24 Machf Gebr Stork & Co N V Centrifugal fan
US2674402A (en) * 1950-09-30 1954-04-06 Westinghouse Electric Corp Blower inlet volume and spin control
US3426667A (en) * 1967-03-17 1969-02-11 American Warming Ventilation Air intake apparatus
US3960527A (en) * 1974-11-22 1976-06-01 Goettl Adam D Air delivery and treatment apparatus
US4108568A (en) * 1977-06-08 1978-08-22 Townsend Darold I Fan rotor means
US5522696A (en) * 1995-01-04 1996-06-04 Aqua-Chem, Inc. Multiple-shutter throttle characterization assembly for burners
US5558493A (en) * 1994-07-18 1996-09-24 Hitachi, Ltd. Forced air cooling apparatus having blower and air current regulating plate that reduces eddy air current at inlet of blower
US5704761A (en) * 1992-04-14 1998-01-06 Ebara Corporation Full-circumferential flow pump
US5980199A (en) * 1996-08-07 1999-11-09 Abb Soylvent-Ventec Performance centrifugal blower apparatus including at least two suction inlets, and associated blower method
US20040187475A1 (en) * 2002-11-12 2004-09-30 Usab William J. Apparatus and method for reducing radiated sound produced by a rotating impeller

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2561840A (en) * 1940-04-09 1951-07-24 Machf Gebr Stork & Co N V Centrifugal fan
US2674402A (en) * 1950-09-30 1954-04-06 Westinghouse Electric Corp Blower inlet volume and spin control
US3426667A (en) * 1967-03-17 1969-02-11 American Warming Ventilation Air intake apparatus
US3960527A (en) * 1974-11-22 1976-06-01 Goettl Adam D Air delivery and treatment apparatus
US4108568A (en) * 1977-06-08 1978-08-22 Townsend Darold I Fan rotor means
US5704761A (en) * 1992-04-14 1998-01-06 Ebara Corporation Full-circumferential flow pump
US5558493A (en) * 1994-07-18 1996-09-24 Hitachi, Ltd. Forced air cooling apparatus having blower and air current regulating plate that reduces eddy air current at inlet of blower
US5522696A (en) * 1995-01-04 1996-06-04 Aqua-Chem, Inc. Multiple-shutter throttle characterization assembly for burners
US5980199A (en) * 1996-08-07 1999-11-09 Abb Soylvent-Ventec Performance centrifugal blower apparatus including at least two suction inlets, and associated blower method
US20040187475A1 (en) * 2002-11-12 2004-09-30 Usab William J. Apparatus and method for reducing radiated sound produced by a rotating impeller

Similar Documents

Publication Publication Date Title
US2201437A (en) Volume control for fans
CN101925783B (en) Air conditioner
US3824028A (en) Radial blower, especially for oil burners
US3276480A (en) Regulator for constant volume of gas flow
US3308744A (en) Strip type air distributor
WO2018040448A1 (en) Centrifugal fan
US3042078A (en) Volume flow regulating device
CN105041682B (en) Volute fan
US3398882A (en) Crossflow blower
US4014625A (en) Transverse flow fan
JPH035633A (en) Air conditioning device
US2974680A (en) Valve
JP4968941B2 (en) Air volume adjustment device in plug fan room of air conditioner.
US2060289A (en) Conditioning apparatus
US2899180A (en) High-velocity air-conditioning
CN204003622U (en) A kind of air flue structure of centrifugal fan
US2083186A (en) Fan
US3367385A (en) Retractible air register
US3295750A (en) Cross flow machine
US3437262A (en) Cross-flow fluid machines
US3322332A (en) Cross flow machine
US1787653A (en) Fan volume and pressure control
US2112955A (en) Conditioning apparatus
CN209704915U (en) Centrifugal fan blade, courtyard machine and air conditioning system with same
US1912164A (en) Load limiting damper