WO1991015664A1

WO1991015664A1 - Space-efficient centrifugal blower

Info

Publication number: WO1991015664A1
Application number: PCT/US1991/002221
Authority: WO
Inventors: Martin G. Yapp
Original assignee: Airflow Research And Manufacturing Corporation
Priority date: 1990-03-30
Filing date: 1991-03-29
Publication date: 1991-10-17

Abstract

A space efficient centrifugal blower (10) having a plenum (50) connected to the impeller inlet opening (39). The plenum has at least one plenum inlet (52) positioned to provide airflow from one side of the impeller in a direction generally perpendicular to the impeller axis. A set of airfoil members (57) positioned in the plenum around the impeller inlet have elongated airflow control surfaces extending outwardly from the impeller inlet in a direction generally perpendicular to the impeller axis, so that the airfoil members act on air flowing from the plenum inlet to direct it radially inwardly and to spread the airflow around the impeller inlet.

Description

SPACE-EFFICIENT CENTRIFUGAL BLOWER Background of the Invention

This invention is in the general field of centrifugal blowers designed for a compact space, such as those used for automobile interior ventilation.

There are many conflicting and demanding constraints on the design of compact blowers such as those used for automotive interior ventilation systems. One serious constraint is the size of the package available to house the system. Increasingly, automotive designers are driven to use all available cabin space efficiently and to balance conflicting demands for space. Another constraint is noise; excessive noise in the cabin will not be tolerated. Power available to drive fan motors is also limited. Other considerations are ease of molding and manufacturing and cost.

Summary of the Invention

The invention generally features a space efficient centrifugal blower having a plenum connected to the impeller inlet opening. The plenum has at least one plenum inlet positioned to provided airflow from one side of the impeller in a direction generally perpendicular to the impeller axis. A set of airfoil members positioned in the plenum around the impeller inlet have elongated airflow control surfaces extending outwardly from the impeller inlet in a direction generally perpendicular to the impeller axis, so that the airfoil members act on air flowing from the plenum inlet to direct it radially inwardly and to spread the airflow around the impeller inlet.

Preferred embodiments of the invention have the following features. The plenum inlet has an opening positioned within a first quadrant of the plenum, and the directional bias of airflow members in the first quadrant increases as a function of their angular position away from the centerline of the plenum inlet. (By directional bias, I mean the angular "turn" effected by a given airfoil member flow control surface, as determined by the change in flow-control angle from the tip to the tail of the airflow member. These characteristics are described in greater detail below. ) Most preferably, the directional bias of the airfoil members increases as a function of angular position moving from 0° to 60° and from 0° to -60° (300°), where 0° is the position of the plenum inlet idline as shown in Fig. 3. One particularly preferred embodiment uses a set of airfoil members (a cascade) that has bilateral symmetry (such as the set discussed immediately above) to efficiently control airflow. For example, the airfoil members may be molded as a plastic part, integral with a plenum face.

The above-described blower is particularly space efficient, and well adapted for use in vehicle (e.g. automotive) cabin ventilation systems. Space efficiency is achieved while minimizing or avoiding trade-offs such as power requirements or noise.

Description of the Preferred Embodiments Drawings

Fig. 1 is a sectional view of a blower according to invention.

Fig. 2 is a view taken along 2-2 of Fig. 1. Fig. 3 is an enlargement of blades in the cascade of Fig. 2. Structure

In Fig. 1, blower 10 is a centrifugal blower suitable for use in an automotive climate control system. The impeller 30 of blower 10 is driven by motor 11 to draw air in through plenum 50, and axially inwardly through the impeller inlet 39. Since many components of the impeller ar standard, there is no need to refer to them in detail here. For example, the blades 32 impeller 30 of blower 10 may be generally designed according to the design disclosed in commonly owned U.S. Patent 4,900,228, which is hereby incorporated by reference, showing a centrifugal blower with an impeller having variably cambered rearwardly curved blades.

The impeller forces air radially outwardly through impeller outlet 35.

In Fig. 2, plenum 50 has inlet 52. Positioned within plenum 50 is a radially oriented cascade 59 of airfoi members 57 having flow control surfaces 58. Figs. 2 and 3 show cascade 59 diagrammatically, to illustrate the change i bias of members 57 as a function of radial position, where 0° is a radial midline through the operative inlet. Each airfoil member 57 redirects air radially from points around the circumference of inlet 39. The bias angle φ (Fig. 4) of the 53 individual evenly spaced airfoil blades is shown in the following table. Bias angle is defined as the angle between the individual blade nose-tail line and a line connecting the nose to the center of the pattern.

Table

- ώ -

.1152

Bulkhead

-.1152

-.0987

-.0823

-.0658

-.0494

-.0329

-.0165

As the table shows, blades 7-26 are identical, and blades 28-46 are mirror images of blades 7-26. Fig. 3 is an enlarged diagram of blades 8-11. Also shown in Table is the maximum blade camber f/c for each of the 53 blades. The maximum camber increase linearly with rotational position.

Maximum camber is zero for the blade on centerline; .0165 for the first blade; twice .0165 for the second blade, and so on until f/c = .1152 for the 7th through 26th blade. It can be seen from the geometry that some diffusion occurs in the blades 7-26. Increasing maximum camber beyond f/c .115 result in flow separation from the blading and a reduction of efficiency.

A bulkhead is placed in the plenum which isolates the left-hand and right-hand halves, and provides a means of achieving stagnation of the flow at 180°. This improves the efficiency of the device.

Other embodiments are within the following claims.

Claims

Claims 1. A centrifugal blower comprising an impeller that rotates on an axis and a motor connected to rotate the impeller, the impeller comprising blades shaped and oriente to draw air in axially through an impeller inlet opening an to exhaust air radially, the centrifugal blower further comprising, a) a plenum connected to the impeller inlet opening, the plenum having at least one plenum inlet positioned to provide airflow from one side of the impeller in a direction generally perpendicular to the impeller axis, and b) a set of airfoil members positioned in the plenum around the impeller inlet, each airfoil member having an elongated airflow control surface extending outwardly fro the impeller inlet in a direction generally perpendicular to the axis, so as to act on air flowing from the plenum inlet, directing the airflow radially inwardly and spreading it around the impeller inlet.

2. The centrifugal blower of claim 1 in which the plenum inlet has an opening positioned within a first quadrant of the plenum, and the directional bias of the airfoil members in the first quadrant generally increases as a function of angular position of the airfoil member away from the plenum inlet centerline.

3. The centrifugal blower of claim 1 in which the directional bias of said airfoil members generally increases as a function of the angular position of said airfoil member from 0° to 60° and from 0° to -60°.

4. The centrifugal blower of claim 3 in which the airfoil cascade is bilaterally symmetrical.

5. The centrifugal blower of claim 4 in which the airfoil members are molded as an integral plastic part with plenum face.

6. The centrifugal blower of claim 1 in which set of airfoils comprises a bulkhead member positioned at 180° from said plenum inlet.