GB2071270A

GB2071270A - Shaft coupling in a motor- driven fan

Info

Publication number: GB2071270A
Application number: GB8024616A
Authority: GB
Original assignee: INDUSTRIA PIEMONTESE RADIATORI AUTOMOBIL SpA
Current assignee: INDUSTRIA PIEMONTESE RADIATORI AUTOMOBIL SpA
Priority date: 1980-03-05
Filing date: 1980-07-28
Publication date: 1981-09-16
Also published as: FR2477647A1; IT8053006V0

Abstract

A fan has a plastics impeller 3 keyed to a motor shaft A by an element 4 of stamped sheet metal harder than the shaft and inserted in a receiving formation in a bore 7 in the impeller hub. The element 4 comprises a baseplate 5 with an aperture 6 through which the shaft A extends, the baseplate having lugs 8 extending, from opposite edges of the plate, perpendicular to the plane of plate 5. Each lug 8 is U-shape in section, the open end of the U facing the other lug. The bottom of the 'U' has a wedge-shaped projection 9 on its surface remote from the other lug. The receiving formation in the hub includes diametrically opposed recesses 12 to receive the lugs 8. On assembly the projections 9 forcibly engage opposing walls of the two recesses. <IMAGE>

Description

SPECIFICATION A motor-driven fan This invention relates to a motor-driven fan for example such as may be used in heating, ventilation and air-conditioning equipment on vehicles, comprising an electric motor and a bladed impeller made of plastics and keyed to an end of the motor shaft.

In some known motor-driven fans of the aforementioned kind, the bladed impeller is keyed to one end of the motor shaft by a keying element made of stamped sheet-metal harder than the motor shaft and having first projections which are inserted in the impeller hub and second projections extending into the aperture in the hub through which the motor shaft extends and having edges which cut into the surface of the shaft when the impeller is mounted on the shaft.

The aforementioned known keying elements have the disadvantage of not being of use when the bladed impeller is made of very rigid material, e.g. plastics reinforced with glass fibre, since in such cases the aforementioned first projections of the keying element may break during the operation in which they are disposed in the impeller hub.

The object of the invention is to provide a motor-driven fan comprising an electric motor and a bladed impeller made of plastics and comprising a stamped sheet-metal keying element which is simple and cheap to manufacture, is more reliabie than the prior keying elements and is of use even when the impeller is made of very hard material.

According to the invention there is provided a motor-driven fan for heating, ventilation and airconditioning plant on vehicles, comprising an electric motor and a bladed impeller made of plastics having a hub with an aperture therein into which extends the driving shaft of the electric motor, the impeller being keyed to an end of the motor shaft by a keying element made of stamped sheet metal harder than the motor shaft, inserted in the impeller hub in which the keying element comprises a planar baseplate formed with a central aperture equal in diameter to the aperture in the hub of the impeller, a pair of lugs extending from opposite sides of the periphery of the base plate and perpendicular to the plane of the base plate, each said lug having, in cross-section parallel with the plane of the base-plate the shape of a 'U' with the open end of the U facing towards the other said lug, the internal longitudinal edges of the flanges affording the free ends of the U's lying on an imaginery cylinder slightly smaller in diameter than the shaft, each said lug on the outer surface of the portion thereof affording the bottom of the U in cross section, having a projection extending longitudinally along the lug and having a wedge-shaped profile, as viewed in section longitudinally along the lug, increasing in height above the respective said outer surface from the free end of the lug towards the baseplate, the keying element being fitted in a receiving formation provided in the impeller hub and disposed adjacent the open end, adjacent the motor, of said aperture in the hub, with the plane of said base plate being perpendicular to the rotational axis of the shaft and the impeller, with said lugs extending into the impeller away from the baseplate and the motor, and with the motor shaft extending through said apertures in the base plate and the rotor, the receiving formation including respective recesses accommodating said lugs, each said recess including a longitudinally extending bottom wall opposing said outer surface of the portion of the respective lug affording the bottom of the 'U', each said bottom wall being forcibly engaged with the respective wedgeshaped projection and the flanges of each lug affording the arms of the U extending from the respective said recess to penetrate, via said internal longitudinal edges thereof, the peripheral surface of the motor shaft, the arrangement being such that, in assembly of the fan, the keying element can first be inserted in said receiving formation in the impeller hub, with the lugs preceding the base plate, and the wedge-shaped formations on the lugs forcibly engaging respective diametrally opposing said bottom walls of said two recesses, and the motor shaft subsequently inserted, via the aperture in the base plate into the aperture in the impeller hub, with accompanying penetration of the longitudinal inner edges of the flanges of the lugs into the peripheral surface of the motor shaft.

The keying element used in the fan according to the invention is more reliable and of wider usefulness than the prior-art devices; it can also key the impeller on to the shaft under conditions which are equally efficient in both directions of rotation.

An embodiment of the invention is described below, by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a motor-driven fan embodying the invention; Figure 2 is a perspective partial view of the bladed impeller and keying element of the fan of Figure 1; Figure 3 is a view in section along line Ill-Ill of Figure 1; and Figure 4 is a view in section along line IV--IV of Figure 3.

In Figure 1 , the general reference 1 denotes a motor-driven fan for heating, ventilation and airconditioning installations on a vehicle.

Fan 1 comprises an electric motor 2 and a blade impeller 3 made e.g. of plastics.

The bladed impeller 3 is keyed to the end of the shaft of motor 2 by a keying element 4 (Figure 2i made of stamped sheet metal harder than the motor shaft.

The keying element 4 has a planar baseplate 5 formed with a circular central aperture 6 equal in diameter to a cylindrical bore or aperture 7 (Figures 2 and 3) in the hub of impeller 3.

The keying element 4 also has a pair of lugs 8 extending in the same direction as one another from opposite sides of the periphery of plate 5, the direction of longitudinal extent of each lug being perpendicular to the plane containing plate 5.

Each lug 8 has, in cross-section parallel with the plane of plate 5, a U-shape, the open end of each U facing the other lug.

The portion of each lug 8 which provides the base of the U has a longitudinal projection 9 on its outer surface, i.e. its surface remote from the other lug, the projection 9 having a wedge-shape in longitudinal section along the lug (Figure 3) increasing in height from the free end of lug 8 towards the baseplate 5.

The internal longitudinal free edges 10 of the flanges which afford the arms of the U's formed by the two lugs 8, and which free edges afford the free ends of the arms of the U's lie on an imaginary cylinder 11 (shown by a chain line in Figure 4) slightly smaller in diameter than the shaft A of motor 2, which shaft A is, of course, itself of slightly smaller diameter than the bore 7.

The hub of impeller 3, on its surface facing motor 2, is formed with a receiving formation around the free end of the bore 7. This receiving formation includes a shallow recess to receive the base plate 5 and extending from this shallow recess longitudinally into the hub, two recesses 12 diametrically opposite one another relative to the axis of hub aperture 7 and which recesses 12 adjoin, and open into the hub aperture 7. The seats 12 have each a depth reckoned in the longitudinal direction, parallel with the axis of bore 7, equal to the length of each lug 8 of keying element 4. The bladed impeller 3 is keyed to the end of the motor shaft A, during manufacture, as follows: The lugs 8 of element 4 are longitudinally inserted into the seats 12 of impeller 3, the free ends of the lugs preceding the base-plate.Each seat 12 has a bottom wall which faces towards the axis of bore 7 and the other seat and which extends longitudinally parallel with the axis of bore 7. The relative dimensions of the element 4 and the recesses 12 are such that when the lugs 8 are inserted in the manner indicated, the projections 9 bear forcibly against the opposing bottom walls of the respective recesses, while the longitudinal edges 10 and the adjacent portions of lugs 8 project into bore 7 from recesses 12.

The wedge-shape of the projections 9 enables lugs 8 of element 4 to be inserted readily into seats 12. However, this wedge-shape opposes removal of fins 8 from seats 12 after such insertion.

Next, the shaft A of the electrical motor is inserted into aperture 7 in the impeller hub via the aperture 6 of element 4. During insertion of shaft A the longitudinal edges 10 of lugs 8 cut into the surface of shaft A as illustrated in Figure 4.

The coupling thus obtained between the bladed impeller 3 and the shaft A of motor 2 is particularly reliable since, as is known, the operation of impeller 3 is influenced substantially only by torsion forces, since the axial stresses applied to the fan are negligible.

Claims

1. A motor-driven fan for heating, ventilation and air-conditioning plant on vehicles, comprising an electric motor and a bladed impeller made of plastics having a hub with an aperture therein into which extends the driving shaft of the electric motor, the impeller being keyed to an end of the motor shaft by a keying element made of stamped sheet metal harder than the motor shaft, inserted in the impeller hub in which the keying element comprises a planar baseplate formed with a central aperture equal in diameter to the aperture in the hub of the impeller, a pair of lugs extending from opposite sides of the periphery of the base plate and perpendicular to the plane of the base plate, each said lug having, in cross-section parallel with the plane of the base-plate the shape of a 'U with the open end of the U facing towards the other said lug, the internal longitudinal edges of the flanges affording the free ends of the U's lying on an imaginary cylinder slightly smaller in diameter than the shaft, each said lug on the outer surface of the portion thereof affording the bottom of the U in cross section, having a projection extending longitudinally along the lug and having a wedge-shaped profile, as viewed in section longitudinally along the lug, increasing in height above the respective said outer surface from the free end of the lug towards the baseplate, the keying element being fitted in a receiving formation provided in the impeller hub and disposed adjacent the open end, adjacent the motor, of said aperture in the hub, with the plane of said base plate being perpendicular to the rotational axis of the shaft and the impeller, with said lugs extending into the impeller away from the baseplate and the motor, and with the motor shaft extending through said apertures in the base plate and the rotor, the receiving formation including respective recesses accommodating said lugs, each said recess including a longitudinally extending bottom wall opposing said outer surface of the portion of the respective lug affording the bottom of the 'U', each said bottom wall being forcibly engaged with the respective wedgeshaped projection and the flanges of each lug affording the arms of the U extending from the respective said recess to penetrate, via said internal longitudinal edges thereof, the peripheral surface of the motor shaft, the arrangement being such that, in assembly of the fan, the keying element can first be inserted in said receiving formation in the impeller hub, with the lugs preceding the base plate, and the wedge-shaped formations on the lugs forcibly engaging respective diametrally opposing said bottom walls of said two recesses, and the motor shaft subsequently inserted, via the aperture in the base plate into the aperture in the impeller hub, with accompanying penetration of the longitudinal inner edges of the flanges of the lugs into the peripheral surface of the motor shaft.

2. A motor driven fan substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

'3. Any novel feature or combination of features described herein.