GB2163215A

GB2163215A - Centrifugal fan inlet vanes

Info

Publication number: GB2163215A
Application number: GB08520070A
Authority: GB
Inventors: Ari Oksanen
Original assignee: Nokia Oyj
Current assignee: Nokia Oyj
Priority date: 1984-08-17
Filing date: 1985-08-09
Publication date: 1986-02-19
Also published as: FI843263A0; FI843263A; GB8520070D0; SE8503710D0; DE3529027A1; SE8503710L; FR2569245A1

Abstract

The stationary vanes at the inlet of the electric motor driven fan impeller 5 may be replaced by a different set of sheet metal vanes in order to change the fan output. The blade mountings may take various forms (Figs. 3 to 6). <IMAGE>

Description

SPECIFICATION A centrifugal fan an adjustment vaneset and a series of adjustment vanes for such a fan This invention relates to a centrifugal fan comprising a frame housing provided with an air intake and an air outlet, an impeller rotatingiy journalled in the housing and directly driven by a motor, and a means supported by the housing for adjustment of the blowing capacity of the fan, said means comprising a number of vanes, projecting into the air intake.

The present invention is mainly intended to be utilized in smaller direct-driven fans with low pressure and constant capacity for e.g. air conditioning purposes.

The operating characteristics of a centrifugal fan, e.g. the volume flow/pressure developed by the fan, which in the following is called blowing capacity, depend on the speed of rotation of the impeller. When theimpeller is directly connected to the axle of the driving motor, the blowing capacity of the fan is thus determined by the speed of rotation of the motor. If some other blowing capacity is wanted for the same fan by using a direct motor drive, the motor must be changed for another motor having a speed of rotation corresponding to the new desired blowing capacity.

In order to make it possible for the manufacturer to avoid storing a great number of various motors, a suggestion has been made to rotate the impeller of the fan by means of a belt gearing. Thus the speed of rotation of the fan impeller can be changed to correspond to the blowing capacity required by the purchaser in each particular case by changing the belt pulleys for suitable ones without being compelled to change the motor. The fan can thus be provided with different blowing capacities by using only one size of motor. If such a fan provided with a belt gearing is only used at constant capacity, the belt gearing means, however, represents an extra cost, because the gearing needs not be changed after the basic adjustment any more.The fact is that a belt gearing requires its own shaft and bearings for the impeller, belts, belt pulleys, a protecting cover, a separate base for the motor and tension rods.

Fans, in which the blowing capacity must be continuously adjustable, are provided with a special vane adjuster comprising a number of vanes mounted to form a circle of vanes in the air intake of the fan and a set of adjusting levers connected to the vanes, by means of which levers the angular position of the vanes in the air intake is adjustable for a change of the blowing capacity. This necessitates that the vanes are rotatingly journalled in the intake cone of the fan. If such a fan provided with a vane adjuster is only used at constant capacity, the vane adjuster represents a considerable additional cost, because the adjustment needs not be changed after the basic adjustment any more.

An object of this invention is to provide a centrifugal fan avoiding the disadvantages mentioned above and making it possible to adjust a direct-driven intended for a constant capacity in a simple way for a blowing capacity wanted in each particular case without changing the speed of rotation of the fan. This object is achieved with a fan according to the invention, characterized in that the adjustment means comprise a detachable fixed set of vanes, which vanes are positioned stationarily with respect to the air intake and have dimensions and an angular position corresponding to a certain constant blowing capacity of the fan.

The invention is based on the idea that in connection with the assembly or afterwards the fan is provided with a special set of adjustment vanes, which are fixed (non-pivotable) and positioned in the air intake of the fan in an angular position exactly corresponding to that blowing capacity, for which the fan is delivered. It is very simple to manufacture and assemble such a set of adjustment vanes.

Corresponding sets of adjustment vanes can be manufactured for different blowing capacities, whereby it is possible to substantially widen the range of use of a direct-driven fan without needing a complicated belt gearing or a vane adjuster.

Thus, another object of the invention is such an adjustment vane set for a fan and a series of adjustment vanes for various blowing capacities. The adjustment vane set and the series of adjustment vanes are characterized by the features stated in claims 5 and 6. The vanes in an adjustment vane set according to the invention can simply be manufactured of sheet metal and bent into the angular position required. It is a known technique per se to choose the dimensions and angular positions of such vanes in order to obtain a specific blowing capacity for a certain fan.

The invention is described in more detail in the following referring to the enclosed drawing, in which Figures 1 and 2 illustrate a preferred embodiment of a centrifugal fan according to the invention in an axial cross-section and in the axial direction respectively, Figure 3 is an axial cross-section of another embodiment of an intake cone of a fan, Figures 4 and 5 illustrate a third embodiment of a fan in an axial cross-section and in the axial direction respectively, and Figure 6 is a perspective view of a series of adjustment vanes consisting of adjustment vane sets.

The fan shown in Figures 1 and 2 of the drawing comprises a housing 1 provided with an air intake 3 defined by an intake cone 2 and with an air outlet 4 and an impeller 5 mounted in the housing and fastened to a shaft 7 of an electric motor 6 supported by the housing.

To the intake cone of the fan is fastened an adjustment vane set 8 according to the invention. It consists of four vanes 9 cut out of sheet metal and a support ring 10, to which the vanes are fastened at even distances around the axle of the support ring. Each vane is provided with a control portion 9a bent into such an angle with respect to a fastening portion 9b of the vane that after the set of vanes has been fastened to the intake cone of the fan, the set of vanes changes the operating characteristics of the fan to correspond to the blowing capacity required for the fan.

The set of adjustment vanes is preferably fastened to the intake cone in connection with the assembly of the fan. Due to the rigid fastening of the vanes, the control portions firmly maintain their angular positions with respect to the intake cone of the fan. The position of the vanes is not supposed to be changed and the fan is supposed to be used at a continuously constant capacity.

By means of the angular position of the control portion of the vanes, the operating characteristics of the fan can be changed. If it is desirable to deliver the same fan for another blowing capacity, the set of adjustment vanes is assembled of vanes provided with control portions having another angular position corresponding to said other blowing capacity.

It is observed that a direct-driven centrifugal fan can be adjusted for use at a specific constant capacity by means of simple, rigidly fastened vanes made of sheet metal. The construction of a set of adjustment vanes is thus very simple and cheap.

The embodiment of the fan shown in Figure 3 deviates from the foregoing only in that the support ring of the set 1 8 of adjustment vanes is left out and the vanes 1 9 are fastened directly to the wall of the intake cone in a corresponding form as in the embodiment above.

In the embodiment of the fan shown in Figures 4 and 5, the vanes 29 of the set 28 of adjustment vanes form a plate-shaped control portion 29a and a fastening pin 29b fastened thereto, by means of which the vanes can be fastened to a support ring 20 in the angular position desired in each particular case with respect to the axle of the support ring and rigidly locked to the support ring after adjustment. The support ring is fastened in front of the intake cone.

Figure 6 shows a series of adjustment vanes for a centrifugal fan comprising adjustment vane sets 8', 8", 8"' consisting of vanes 9', 9", 9"', of different dimensions and/or with different angular positions, which sets are designed for obtaining different blowing capacities for a fan of a certain kind. Each set of vanes then comprises several similar vanes. A manufacturer of fans needs to store only such simple vanes of sheet metal, from which he chooses a suitable set of adjustment vanes by means of which the blowing capacity, which in each particular case is desired by the purehaser, is obtained.

The drawing and the description attached thereto are only intended to visualize the idea of the invention. As to the details, the fan and the adjustment vane set according to the invention can vary within the scope of the

Claims

claims. CLAIMS

1. A centrifugal fan comprising a frame housing (1) provided with an air intake (3) and an air outlet (4), an impeller (5) rotatingly journalled in the housing and directly driven by a motor (6), and a means supported by the housing for adjustment of the blowing capacity of the fan, said means comprising a number of vanes (9; 19; 29), protecting into the air intake, characterized in that the adjustment means comprise a detachable fixed set (8; 18; 28) of vanes, which vanes (9; 19; 29) are positioned stationarily with respect to the air intake (3) and have dimensions and an angular position corresponding to a certain constant blowing capacity of the fan.

2. A fan according to claim 1, characterized in that the set (18) of adjustment vanes comprises a number of separate plate-shaped vanes (19) separately stationarily fastened to the intake cone (2) at mutual distances around the axle of the air intake (3).

3. A fan according to claim 1, characterized in that the set (8; 28) of adjustment vanes comprises a number of separate plate-shaped vanes (9; 29) stationarily fastened to a common support ring (10; 20) at mutual distances around the axle of the support ring, said support ring being stationarily fastened to the intake cone (2).

4. A fan according to claim 2 or 3, characterized in that the vanes (9; 19; 29) are pieces cut out of sheet metal.

5. An adjustment vane set for a centrifugal fan, which set (8; 18; 28) comprises vanes (9; 19; 29) to be fastened to a housing (1) of the fan, said vanes forming control portions (9a; 29a) extending into an air intake (3) of the fan, characterized in that the vanes (9; 19; 29) are formed of separate pieces, whereby the control portion (9a; 29a) of the vane is positioned rigidly with respect to a fastening portion (9b; 29b) to be fastened stationarily to the housing (1) of the fan and whereby the control portion of the vane has dimensions and an angular position corresponding to a certain blowing capacity of the fan.

6. A series of adjustment vanes for a centrifugal fan, which series comprises vanes (9) to be fastened to a housing (1) of the fan, said vanes forming control portions extending into an air intake (3) of the fan, characterized in that said series comprises adjustment vane sets (8', 8", 8"') corresponding to different blowing capacities of the fan, each set comprising vanes (9', 9", 9"') formed of separate pieces, and that the control portion (9a) of the vane is positioned rigidly with respect to a fastening portion (9b) to be fastened stationarily to the housing of the fan, whereby the dimensions and the angular position of the control portions of the vanes of different sets correspond to different blowing capacities of the fan.

7. A set of vanes and a series of vanes according to claim 5 or 6 respectively, characterized in that the vanes (9; 19; 29) of a set (8; 18; 28; 38') of vanes are plate-shaped and that the control portion (9a) of each vane is bent into a stationary angular position with respect to the fastening portion (9b) of the vane.

8. A set of vanes and a series of vanes respectively according to claim 7, characterized in that the vanes (9; 29) of a set (8; 28) of vanes are stationarily fastened to a common support ring (10; 20) at mutual distances around the axle of the support ring.

9. A set of vanes and a series of vanes respectively according to claim 7 or 8, characterized in that the vanes (9; 19; 29) are pieces cut out of sheet metal.

10. A centrifugal fan substantially as hereinbefore described with reference to, and as shown in, Figures 1 and 2 of the accompanying drawings.

11. A centriugal fan substantially as hereinbefore described with reference to, and as shown in, Figure 3 of the accompanying drawings.

12. A centriugal fan substantially as hereinbefore described with reference to, and as shown in, Figures 4 and 5 of the accompanying drawings

1 3. Any novel feature or combinaton of features described herein.