Air impeller and devices incorporating air impellers

Abstract

 An air impeller comprising a fan (12) situated within the air duct and driven by a switched-reluctance motor, air impelled by the fan passing through the rotor ()2) of the motor. Air guides (20) may be interposed between the motor armature and the fan. The fan may be a centrifugal fan. The impeller is applicable to vacuum cleaners, air-cushion-supported lawn mowers, leaf blowers, air conditions, hand driers, hair driers, hot-air heaters and the like.

Description

[0001] This invention relates to air impellers, in particular electrically driven air impellers, and to devices incorporating such air impellers, for example vacuum cleaners, air-cushion-supported lawnmowers, leaf blowers, air conditioners, hand driers, hair driers, hot-air heaters and the like.

[0002] Such impellers comprise an electric motor driving a fan to provide the air flow. The motor is normally of the induction type and requires cooling. This is generally provided by a separate flow of cooling air generated by an additional fan mounted on the armature shaft, or it may be provided by part or all of the air flow generated by the main fan being caused to pass over the outside of the motor.

[0003] The present invention, which is defined in the appended claims, depends on the use of a motor of the switched-reluctance type. The armature of such a motor has salient poles without any windings and so presents a large "window" through which air can flow. Such motors can run at high speeds, which makes them particularly suitable for driving centrifugal fans.

[0004] Preferably the motor is positioned upstream of the fan, so that it is not subjected to the heat generated by the fan and is, therefore, more efficiently cooled.

[0005] The motor armature itself produces a pumping action and this may be further increased by appropriate shaping of the pole pieces. Air guides may be positioned downstream of the rotor to redirect the flow of air as it leaves the armature.

[0006] The invention will be further described by way of example with reference to the accompanying drawings, in which

[0007] Figure 1 is a diagrammatic end view of a motor to be used in the present invention.

[0008] Figure 2 is an axial section through an air impeller according to the invention.

[0009] Figure 3 is a longitudinal section through a wheeled domestic vacuum cleaner incorporating the invention.

[0010] Referring first to Figure 1 which is a much simplified end view of the motor, the motor comprises a stator 1, the windings and pole structure of which are not shown in the figure, and a rotor or armature 2. The motor is of the switched-reluctance type, designed to run at 40 000 rpm and areas 3 between the rotor poles, shown shaded, are not occupied by windings, and so present a large area allowing for the free passage of air through the motor. The pole pieces are of a slightly oblique section, so as to exert a pumping action as they rotate.

[0011] Figure 2 is an axial section through an air impeller designed to form part of a domestic vacuum cleaner. The impeller comprises an outer housing in two sections 10, 11, containing the motor and fan, and which define a duct for the air passing through the impeller. The fan 12 is mounted on the rotor shaft 13, which rotates in ball bearings, 14, 15, respectively, in the housing sections 10,11.

[0012] Section 10 houses the motor stator 1 and is provided with apertures 17 for the inflow of air, while the section 11 houses the fan 12, and is provided with apertures 10 at its periphery for the outflow of the air. The rotor 2 has large window areas between its poles through which the air can pass, and between the motor and the fan 12 is positioned an air guide 20 which redirects air emerging from the rotor into an axial direction of movement.

[0013] In use of the vacuum cleaner, air entering the nozzle and passing through the hose is drawn through the dust bag into the impeller unit by way of the apertures 17, subjected to a first pumping action due to the rotor 2, re-directed axially by the air guides 20, and then pumped out through the peripheral apertures 19 by the fan 12.

[0014] Figure 3 shows a longitudinal section of a wheeled vacuum cleaner machine 21 with hose attachment which includes the motor of the present invention.

[0015] The motor of the machine 21 draws air from the hose into the machine body 22 via a machine inlet 23. The air then passes into a duct collection bag 24 which filters dust and debris from the air. The air then passes into the motor unit through apertures 17 in the outer housing 10 of the motor. The air experiences a pumping action from the interaction of the stator 1 and the oblique rotor or armature 2 as the rotor 2 rotates with respect to the stator 1. This causes the air to be drawn through the areas 3 between the poles of the rotor 2. The rotor 2 is mounted on a rotor shaft 13 which in turn is mounted for rotation in bearings 14,15.

[0016] The air then passes past the air guide 20 into the section 11 which houses the fan 12. The fan 12 is mounted on the rotor shaft 13 and, when the motor is operating, draws air through the motor and impels the air out of the housing section 11 through apertures 10. The air is then vented to atmospheric air through a machine outlet 25 in the machine body 22.

Claims

1. An air impeller comprising a fan situated within an air duct and driven by an electric motor, characterised in that the motor is a switched-reluctance motor and at least the armature of the motor lies within the duct so that air impelled by the fan passes through the armature.

2. An air impeller according to claim 1 in which the motor armature is positioned upstream of the fan so that air impelled by the fan passes first through the motor armature.

3. An air impeller according to claim 2 in which one or more air guides are interposed between the motor armature and the fan.

4. An air impeller according to any preceding claim in which the poles of the armature are shaped so as to exert a pumping action on the air passing through them.

5. An air impeller according to any preceding claim in which the fan is a centrifugal fan.

6. An air impeller according to any preceding claim in which the motor is designed to operate at a speed exceeding 10 000 revolutions per minute.

7. A vacuum cleaner incorporating an air impeller according to any preceding claim.

Drawing