EP0564938A1

EP0564938A1 - Centrifugal fan for automobile ventilation and heating

Info

Publication number: EP0564938A1
Application number: EP93105122A
Authority: EP
Inventors: Renato Criscuolo
Original assignee: ELETTROVAGO SpA
Current assignee: ELETTROVAGO SpA
Priority date: 1992-04-06
Filing date: 1993-03-29
Publication date: 1993-10-13
Also published as: ITTO920311A1; IT1259518B; ITTO920311A0

Abstract

A centrifugal fan for automobile ventilation and heating, of the type comprising a half-shell for containing and bearing an electric motor (14) on the shaft of which the hub (13,13') of a centrifugal impeller (10) is mounted. The impeller is substantially cylindrical in shape and has peripheral blades (11) and a plurality of surfaces (12,22,23;30,32) that connect the blades (11) to the hub (13,13'). The half-shell and the impeller (10) are contained within a casing provided with an inlet for the air that is sucked up from front openings of the impeller (10) and an outlet for delivering the air from the impeller (10) to the driver's cabin.

The surfaces (12,22,23;30,32) connecting the blades (11) to the hub (13,13') form further blades (21,31) which determine a second impeller, coaxial to the first one and integral thereto, which is interposed between the inside of the half-shell (15) and the peripheral blades (11).

Description

The present invention falls within the field of automobiles, and more particularly relates to a centrifugal fan for air conditioning, heating and ventilation of cars.
Centrifugal fans for ventilating and, if necessary, heating the driver's cabin are known in which an impeller which is coaxially mounted with respect to its own electric motor, situated below.
The lower part of this motor is usually contained within a half-shell that is provided with an air intake. The latter is connected to a casing which is located in a high pressure zone. The air intake allows the air to penetrate in the lower part of the impeller, that is in the motor containing half-shell. As the fan, due to its own action, generates a depression in its inner part, the concurrence of high pressure in the low part and depression in the high part creates an air circulation that flows on the outer and/or inner parts of the motor, according to the structure of the type of motor that is used (open or closed).
The connection between the fan hub and the blades that form the outer structure is normally of a continuous type, with air passage holes. As an alternative, the connection may be formed by a sheaf of thin plane spokes that determine gaps for the impeller motor air-cooling circulation.
The air flow for cooling said motor is rather scarse. It is an object of this invention to overcome the above drawback by providing a device that is able to increase the motor air-cooling flow considerably in comparison with systems that are known at present.
It is another object of the invention to provide a device of simple construction that does not involve addition of parts to known ventilation and heating devices.
These and further objects and advantages, which will be more apparent hereinafter are attained by the invention by a centrifugal fan for automobile ventilation and heating, of the type comprising a half-shell for containing and bearing an electric motor on the shaft of which the hub of a centrifugal impeller is mounted, the impeller being substantially cylindrical in shape and having peripheral blades and a plurality of surfaces connecting said blades to the hub; the half-shell and the impeller being contained within a casing provided with an inlet for the air that is sucked up from front openings of the impeller and an outlet for delivering the air from the impeller to the driver's cabin; an air passage being provided for delivering air coming from the impeller to the half-shell and from the latter to the blades of the impeller itself; characterised in that the surfaces connecting the blades to the hub form further blades which determine a second impeller, coaxial to the first one and integral thereto, which is interposed between the inside of the half-shell and said peripheral blades.
Two preferred but not-limiting embodiments of the centrifugal fan according to the invention are described hereinafter with reference to the accompanying drawings, in which:

fig. 1: is a top view of a first embodiment of the centrifugal fan according to this invention:
fig. 2: is an axial cross section of the fan of fig. 1;
fig. 3: is a front view of a detail of fig. 1;
fig. 4: is a fragmentary perspecive view of a fan according to the invention, mounted in its seat in its working position;
fig. 5: is a top view of a second embodiment of the fan according to the invention;
fig. 6: is a bottom view of the fan of fig. 5; and
fig. 7: is an axial section of the fan on the line VII-VII of fig. 5.

With reference to the drawings, a centrifugal fan or impeller 10 comproses a plurality of curved peripheral blades 11 that are connected to a central hub 13 by means of radial spokes 12. The hub 13 is coaxially mounted on the rotor axis of a brushless electric motor 14 that is sketched in figs. 1 and 2. As it is shown, each spoke 12 has a blade portion 21 adjacent to the hub 13. Two outwardly and downwardly inclined spines 22 and 23 extend from the blade portions 21 and are connected to an annular base 24 that is joined to the peripheral blades 11.
Referring to fig. 4, the impeller 10 and the motor 14 situated below, that is contained in a half-shell 15 with an air intake 16, are both contained within a superior casing 17 having a air inlet 18 and an air outlet 19 through which air is delivered from the impeller 10 to the driver's cabin.
As stated in the preamble of the description, in operation the blades 11 expel the air from the inside of the impeller 10 towards the outside. Then, the air is collected by the casing 17 and sent to the outlet 19. Consequently, the depression that is formed at the inside of the impeller causes new air to be drawn through the inlet 18. Part of the air that is driven by the blades 11, instead of being expelled from the outlet 19, is simultaneously driven into the air intake 16 (fig. 4, arrow A). This part of air penetrates underneath the motor 14 and then flows upwardly through openings 20 that are obtained in the motor 14, cooling it. While ascending, this part of air reaches the depression zone inside the impeller 10 where it gets mixed with new air and centrifugated again by the blades 11.
According to the invention, while performing their conventional function of connecting the inner and outer parts of the impeller, the spokes 12 have the function of increasing the air flow through the openings in the motor 14 (fig. 2, arrows B). Accordingly, the blade portions 21 are suitably inclined (fig. 3) like propeller blades, thereby forming a real axial fan that draws air from underneath as the impeller rotates. This action, in addition to the other cited effects, considerably increases the air flux that passes through the motor 14 and cools it.
According to this invention, an alternative embodiment is shown in figs. 5 to 7. In the present variant, the centrifugal fan 10 is so shaped as to allow a radial flux of cooling air that comes from the motor underneath and is directed on the peripheral blades 11.
Referring to fig. 7, the hub 13' bears a cap 30 having downwardly directed concavity. The peripheral edges of the cap 30 are rigidly connected to a substantially truncated-cone upwardly tapered surface 32 by means of a plurality of radially disposed vertical blades 31.
The surface 32 is joined to the annular base 24 which is in turn connected to the peripheral blades 11.
Such an arrangement allows cooling air coming from underneath (fig. 7, arrows C) to be regularly conveyed without turbulence through the vertical blades 31 and then radially driven onto the peripheral blades 11 of the impeller 10.
Moreover, owing to the screening action of the cap 30, fresh air coming directly from the inlet 18 is driven onto the peripheral blades 11 without interfering with the air coming up from the motor.
As it can be appreciated, the centrifugal fan according to the invention is particularly advatageous for those cases in which it is driven by a brushless electric motor with an external rotor and with incorporated power electronics, as the latter require additional ventilation for cooling.
The invention is not limited to the aforegoing description and drawings, which are to be considered purely as an illustration of the best mode so far devised for the practical application of the principles thereof. Modifications are possible in the terms of the shape, dimensions and arrangement of the parts and of the constructional and operational details. The invention includes all modifications that fall within its scope, as defined by the following claims.

Claims

A centrifugal fan for automobile ventilation and heating, of the type comprising a half-shell (15) for containing and bearing an electric motor (14) on the shaft of which the hub (13,13') of a centrifugal impeller (10) is mounted, the impeller being substantially cylindrical in shape and having peripheral blades (11) and a plurality of surfaces (12,22,23;30,32) connecting said blades (11) to the hub (13,13'); the half-shell (15) and the impeller (10) being contained within a casing (17) provided with an inlet (18) for the air that is sucked up from front openings of the impeller (10) and an outlet (19) for delivering the air from the impeller (10) to the driver's cabin; an air passage (16) being provided for delivering air coming from the impeller to the half-shell (15) and from the latter to the blades (11) of the impeller (10) itself; characterised in that the surfaces (12,22,23;30,32) connecting the blades (11) to the hub (13,13') form further blades (21,31) which determine a second impeller, coaxial to the first one and integral thereto, which is interposed between the inside of the half-shell (15) and said peripheral blades (11).
A centrifugal fan according to claim 1, characterised in that said surfaces connecting the blades (11) to the hub (13) comprise portions (21) that are equally disposed about the hub (13) and are inclined as blades of an axial propeller, forming said second impeller.
A centrifugal fan according to claim 1, characterised in that said surfaces connecting the blades (11) to the hub (13') are formed by a cap (30) having a plurality of radially disposed vertical edge blades (31) that form said second impeller, of centrifugal type.