US2719666A

US2719666A - Regulator device for a centrifugal blower

Info

Publication number: US2719666A
Application number: US276645A
Authority: US
Inventors: John H Hollingsworth; Karl L Bedell
Original assignee: HOLLY Manufacturing Co
Current assignee: HOLLY Manufacturing Co
Priority date: 1952-03-14
Filing date: 1952-03-14
Publication date: 1955-10-04
Anticipated expiration: 1972-10-04

Description

Oct 5 J. H. HOLLINGSWORTH ETAL 2,719,666

REGULATOR DEVICE FOR A CENTRIFUGAL BLOWER I Filed March 14, l

m M m m JOHN H. HOLL l/VGS WOR TH KARL L. BEDELL a F m APPROXIMATELY 2/3 RAD/US 0F FAN APPROX/MA TEL r //2 x A ORNEY APPROX/MA TEL r M? x United States Patent Ofiice 2,719,666 Patented Oct. 4, 1955 REGULATOR DEVICE FOR A- CENTRJFUGAL BLOWER John H. Hollingsworth, Altadena, and Karl L. Bedell, Pasadena, Calif., assignors to Holly Manufacturing (Iompany, Pasadena, Calif., a corporation .ofCalifoi-nia Application March 14',- 1952, Serial No. 276,645

4 Claims. (Cl. 230-414) This invention relates to improved dampers for use in controlling the delivery of air ,or' other fluids from a blower.

Conventional dampers are located in the discharge duct adjacent to or some distance down stream from the outlet of the blower. Dampers of this type reduce the delivery of the blower by increasing the static pressure against which the blower must operate. Since large static pressures are produced, such arrangements are inherently noisy and subject to leakage through any openings or joints in the duct system. Dampers of this type require a powerful operating mechanism because of the large static pressures involved. Also, such' dampers deflect the air or other fluid which is discharged past the damper and this tends to create unequalpressures on any'branch ducts which are located immediately down stream from the damper.

These difficulties are overcome in our invention by providing a damper located in the housing of the blower which serves to change the efli'ciency of the blower, rather than to increase the static pressure against which the blower must operate.

Inaccordance with our invention, the damper islocated in the housing of the blower adjacent to the blades of the blower wheel so that the damper serves to cut the air or other fluid from the blower wheel. The damper also serves to deflect the air or fluid into the'blades' of the blower wheel so as to create turbulence within the scroll. This action serves to reduce the efficiency of the blower so that less pressure is created within the blower and so that the delivery of the blowercan be controlled by a damper which is considerably smaller than dampers which are employed in conventional blowers. The location of the damper within the scroll of the blower can be varied within limits, but it must be located adjacent the blades of the blower wheel.

Since our damper does not create large static pressures within the blower, it is not as noisy as conventional dampers. The force required to adjust the position of the damper is less than that required for conventional dampers, and consequently a smaller, lighter Weight and less powerful operating mechanism is required.

The invention is explained with reference to the drawings, in which:

Fig. 1 is an elevation of the outlet end of the blower; and

Fig. 2 is a sectional view along line 2-2 of Big, 1.

A conventional blower is shown in: the drawings; It comprises a scroll "housing with. a blower wheel 12 rotatably mounted in the housing. The blades of the blower wheel ordinarily extend parallel to the axis of rotation of the blower wheel. The housing has two

inlet passageways

14 and 16 for. air located around-the axis of rotation of the blower wheel, and an outlet passageway 18 for the air delivered by the blower. In some blowers only one inlet passageway is provided. Ordinarily a cutoff 20 is provided on the scroll at a location intermediate the blower wheel and the outlet passageway for causing the air which is carried by the blades of the blower wheel to be delivered to the outlet passageway.

Our damper may be employed in various types of blowers, and it will be apparent that his not limited to use in the particular type blower described above.

The damper comprises a vane 22 of rectangular shape which extends parallel to the axis of rotation of the blower wheel. The vane 22 is secured to a shaft 24 which is journaled in a pair of

bearings

26, 28 which are aflixed to the housing. A portion of the shaft 24 extends outside the scroll, and an arm 30 is affixed to this portion of the shaft for adjusting the position of the vane. The position of the arm 30 may be adjusted by any suitable operating mechanism. It will be apparent that the position of the shaft 24 may be adjusted in other manners which are well known and will not be disclosed herein.

Preferably the vane22 is mounted off-center on the shaft 24. Since the vane 22 is located adjacent the blades of the blower wheel and the transverse. dimension of the vane 22 extends different distances from the blower wheel, the forces exerted. by the fl'ow' of air against the portions of the vane 22 which are closest to the blower wheel are greater than-the forces exerted against the portions of the vane 22 which are farthest from the blower wheel. With the axis about which the vane 22 is rotatable offset toward the blower wheel from the longitudinal axis of the vane as shown in the drawings, the forces applied by the flow off. air againstthe portions of the vane on each side of the shaft are approximately balanced when the blower is operating. With such an arrangement less force is'required tomove the vane than would be required if the vane were centered about the shaft '24.

The vane 22 is located adjacent the path of the blades of the blower wheel and in the space between the blower wheel and the wall of. the housing at the side of the outlet passageway which is opposite the cutoff 20 on the scroll. Since the vane 22 is employed to change the efficiency of the blower wheel, rather than being em ployed to increase the static pressure against which'the blower must operate as in conventional dampers, the vane is considerably smaller than conventional dampers. The area of the vane 22 is. less: than the cross-sectional area of the outlet passageway 18, whereas" conventional dampers have an area which is equal to or larger than the outlet passageway so that the flow of fluid through the outlet passageway can be controlled by adjusting the size of the opening between the damper and the outlet passageway.

Fig. 2 shows the damper substantially closed. In

' order to open thedamper, the'vane 22 is rotated approximately in a clockwise direction so that the transverse dimension of the vane extends parallel to the direction of flow of air from the bladesof the blower wheel toward the outlet passageway and the delivery of air from the blower wheel tothe outlet is not appreciably affected by the vane.

Stops 31A and 318150;; defining the-.limits-of movement of the vane may be provided in the housing if desired. It will be apparent that the

stops

31A and 31B may be omitted and that other typ of stops for limiting the movement of the vane may-be provided. in the operating mechanism if desired, Such stops may be of various conventional types and arenot shown in the drawings.v

When the vane 22 is in a closed. or apartially closed position, it cuts air from the blower wheel and deflects the air into the blower wheel so that the pressurized air is recirculated through the blades of the blower wheel. In effect, the vane serves as an adjustable cutoff for the air carried by the blower wheel.

When the vane 22 is in its closed position, the recirculation of air causes some air to be forced out of the portions of the inlets which are adjacent the vane even thoughsome air is being drawn into the other portions of the inlets.

The recirculation of air in the blower wheel causes turbulence which reduces the efiiciency of the blower so that much smaller pressures are developed within the blower than are developed by blowers having conventional dampers which are located farther down stream.

Fig. 2 of the drawings show the relative dimensions and location of the damper with respect to the blower wheel and the scroll of the blower in a preferred design. It has been found that these dimensions can be varied somewhat without materially affecting the function of the damper.

Preferably, the axis about which the vane is rotated is spaced from the projection of the axis of rotation of the blower wheel toward the surface 32., a distance equal to approximately two-thirds the radius of the blower wheel, as shown in Fig. 2. However, it has been found that considerable variation in this dimension is permissible and that the vane is effective if the axis about which it is rotatable is located within the space which is bounded by the projection of the axis of rotation of the blower wheel and the projection of the outer periphery of the blower wheel which is adjacent the outletv passageway, toward the surface 32 of the scroll. are along planes which are disposed at right angles with respect to the axis of the outlet passageway 18.

When the axis of rotation of the vane 22 is located as shown in Fig. 2, the width of the vane is preferably equal to approximately five-sixths the distance between the outer periphery of the blower wheel and the surface 32.

It will be apparent that the dimensions shown in Fig. 2 are those preferred for a blower of a certain configuration and capacity, and that the preferred dimensions for other types of blowers would be somewhat dilferent. In order to employ the invention in other types of blowers, the dimensions should be arranged so that the damper vane is located in the housing of the blower adjacent the outer periphery of the blades of the blower wheel and adjacent the outlet portion of the housing so that the damper vane may be employed to change the efliciency of the blower.

We claim:

1. In a blower for fluids comprising a scroll housing formed by a peripheral wall having opposite ends and a pair of oppositely disposed side walls, said housing having a central inlet and a horizontally extending dis charge portion, said portion having a longitudinal axis and said portion terminating in a vertical plane, said horizontally extending portion including one end of said peripheral wall, the other end of said peripheral wall extending into the discharge portion forming a cutoff located inwardly of said vertical plane toward the axis of said scroll housing, a blower wheel rotatably mounted in said housing having an axis of rotation at right angles to said vertical plane, a damper vane having oppositely disposed edges, said damper vane having a shaft providing an axis of rotation for said vane between said edges so that a part of said vane is located on both sides of said axis, said shaft extending in the same general direction as the axis of rotation of the blower wheel and mounted in said side walls for rotation in said scroll housing, said axis of rotation of said damper vane shaft being adjacent said horizontally extending discharge portion and disposed in a space in the housing, said space being bounded by a vertical plane from said peripheral wall through the axis of the blower wheel, a second These projections 1 vertical plane from the peripheral wall and tangential to the outer periphery of the blower wheel, and said damper vane shaft axis being located in a third horizontal plane through said horizontally extending discharge portion approximately midway between the periphery of the blower wheel and the peripheral wall of the blower housing, one side of said damper vane having a surface area of less than the cross-sectional area of the space between the periphery of the blower and said peripheral wall of said housing taken on a vertical plane through the axis of rotation of said damper vane.

2. In a blower for fluids having a scroll housing formed by a peripheral wall having opposite ends and a pair of oppositely disposed side walls, the housing having a central inlet and having a discharge portion which ineludes one end of said peripheral wall said discharge portion forming a discharge passageway, said passageway having a longitudinal axis, a cutoff for fluids to be discharged located at the other end of said peripheral wall, and a blower wheel rotatably mounted in the housing and having an axis of rotation which is disposed at right angles with respect to the side walls of the housing, the improvement which comprises a damper vane having oppositely disposed edges, the damper vane having a shaft providing an axis of rotation for the vane between said edges so that part of the vane is located on each side of the axis, the shaft extending in the same general direction as the axis of rotation of the blower wheel and being rotatably mounted in the side walls of the housing, the axis of rotation of the damper vane shaft being located adjacent the discharge portion of the housing and being disposed in a space in the housing which is bounded by a first plane passing through the axis of rotation of the blower wheel and disposed perpendicularly with respect to the axis of the discharge passageway of the housing and by a second plane passing through the outer periphery of the blower wheel and disposed parallel with respect to the first plane, said damper vane shaft axis being located in a third plane disposed at right angles with respect to the other two planes and located approximately midway between the outer periphery of the blower wheel and the peripheral wall of the blower housing, and one side of the damper vane having a surface area which is less than the cross-sectional area of the space between the outer periphery of the blower wheel and the peripheral wall of the housing along a fourth plane through the axis of rotation of the damper vane and disposed parallel with respect to the first and second planes.

3. Apparatus according to claim 2 in which the axis of rotation of the damper vane is asymmetrically disposed so that there is a larger proportion of the vane on one side of the axis than on the opposite side.

4. Apparatus according to claim 2 in which the axis of rotation of the damper vane is spaced from the plane passing through the axis of rotation of the blower wheel perpendicular to the axis of the discharge passageway a distance that is approximately two-thirds the radius of the blower wheel.

References Cited in the file of this patent UNITED STATES PATENTS 783,267 Harris Feb. 21, 1905 826,869 Ortrnann July 24, 1906 1,787,653 Anderson Jan. 6, 1931 2,014,507 Price Sept. 11, 1935 2,478,457 Camerino et a1. Aug. 9, 1949 FOREIGN PATENTS 114,100 Germany Jan. 28, 1900 556,746 Germany Aug. 13, 1932