FR2781844A1 - Motorized ventilator group for air conditioning in motor vehicle has centrifugal turbine driven by motor in involute casing - Google Patents

Abstract

The motor ventilator group (10) has a centrifugal turbine (12) driven by a motor (16). The air inlet duct (22) delivers tangentially by the action of an involute housing (24), via an outlet duct (26), to an exit conduit (28). The radial plane of the turbine and the involute (32) is inclined at an angle Beta to the axis of the outlet duct so that the air flow (36) expelled by the involute is parallel to the main direction exit flow (34).

Description

-1 motor-fan unit with air characteristics

  improved, in particular for heating and air conditioning

motor vehicle station

  The present invention relates to heating devices

  ventilation of motor vehicles, and more precisely the subassembly called "motor-fan group" or "blower"

incorporated into these devices.

  The motor-fan unit includes a housing housing a centrifugal turbine driven by a motor to discharge a flow of pressurized air to an outlet pipe. This air flow then passes through a heating-refrigeration block mounted downstream of the motor-fan unit and comprising a heat exchanger (radiator and possibly evaporator) allowing the air to be heated or cooled which will then be delivered to the passenger compartment by various pipes and vents

distribution.

  In practice, it can be seen that the speed of the air leaving the motor-fan unit is not uniform. In particular, it has a lateral component of inclination with respect to

  in the radial plane of the turbine (here and below, the orient-

  "radial" or "axial" tation will be understood in relation to the main axis of the centrifugal turbine, axis about which

  this is driven by the group motor).

  Therefore, if an accessory (filter, evaporator, etc.) is placed directly at the outlet of the fan assembly, the air flow will not be evenly distributed over this accessory, only part of which will be used or

fully used.

  To avoid this drawback, it is known to have in

  the outlet duct of the fan motor unit of the

  air vents or "blades" which force the air flow in the direction of the radial plane, that is to say which make the main direction of flow of this flow substantially perpendicular to the inlet of the accessory placed downstream of

motor-fan unit.

  This way of proceeding, however, requires adding blades in the air outlet pipe, generally in the form of attached parts or in one-piece forms molded directly with the pipe. In either case, the presence of these blades implies an additional manufacturing cost for the motor-fan unit, in addition of course to the mechanical drawbacks resulting from the presence of these

  elements added to the interior of the pipe.

  In addition, the presence of blades introduces additional pressure drops, which must be compensated by a higher electrical power of the engine if one wants

  satisfy the planned aeraulic performance.

  One of the aims of the invention is to propose a motor-fan group structure which, without any recourse to blades or similar flow rectifying members, makes it possible to directly obtain an air flow oriented perpendicularly to the inlet. of the accessory or device supplied by this air flow. The motor-driven fan assembly of the invention is of the known type comprising an approximately cylindrical case housing a centrifugal turbine driven by a motor and capable of sucking the surrounding air axially by an air inlet and discharging it radially towards the exterior, this casing further comprising a peripheral volute enveloping with

  an increasing section of the turbine and able to deflect tangent

  and repress the air flow thus produced towards a

  outlet pipe extending in a main direction

  fluid flow blade According to the invention, the assembly formed by the turbine and the volute is disposed inclined with respect to the outlet pipe, with the radial plane of the turbine forming an angle with respect to the main direction of flow in the outlet pipe, the direction and angle of inclination being chosen so as to direct the flow of air expelled by the volute substantially parallel to the main direction

  flow in the outlet pipe.

  The assembly formed by the turbine and the volute can in particular

  link be tilted on the opposite side to that of the air inlet of

the turbine.

  The angle of inclination can be between 0 and 15, from

preferably between 5 and 10.

  Other characteristics and advantages of the invention

  will appear on reading the detailed description below

  below an exemplary embodiment, made with reference to

attached drawings.

  Figure 1 is a sectional view, in an axial plane, of a

  motor-fan unit according to the prior art.

  Figure 2 is a sectional view, in an axial plane, of a

  motor-fan unit according to the invention.

  In the figures, the reference 10 generally designates the

  motor-fan unit of a heating-air conditioning device

motor vehicle station.

  This group comprises, in itself known manner, a centrifugal turbine 12, which has for example a general shape of a flattened cylinder, of axis 14. This turbine is provided at the periphery with a series of blades joined together by a external circular crown, and it is mounted

  on the shaft of a motor 16 which drives it in rotation.

  When the turbine 12 is rotating, the air is entrained by

  the turbine blades in the outward radial direction

  laughing, which produces a suction of air axially (as illustrated by the arrow 18) by an opening or "ferrule" of entry 20 connected to an air intake pipe 22. Due to the rotation of the turbine, the air thus sucked in is discharged in the radial direction, and the fan unit

  has an element called "volute" 24 which wraps around

  preferentially with an increasing section the turbine 12 so as to collect this flow of air expelled radially by the turbine and direct it via an outlet mouth 26 towards an outlet pipe 28. This pipe 28 will then deliver the air stream to a heating-air conditioning unit where it will pass through various elements such as heat exchanger, filter, flow metering flaps, etc. With the fan motor units of the prior art, it can be seen in practice that the air flow has (as illustrated by the arrow 30 in FIG. 1) an inclination of an angle a with respect to the radial plane 32. In in other words, the main direction of the air flow is not perpendicular to the main axis 34 of the outlet pipe 28. This offset, which results from the geometry of the turbine in its housing, occurs in the opposite direction to that of the air inlet shell 20, that is to say that the air flow is deflected, with respect to the radial plane 32, in the half-space

located on the motor side 16.

  This notably results in a poor distribution of the air flow over the accessory (filter, heat exchanger,

  etc.), therefore a lower efficiency of it.

  To remedy this difficulty and avoid resorting to the known solution consisting in setting up blades in the outlet mouth 26, the invention proposes to produce the motor-fan group with the illustrated configuration.

figure 2.

  In this configuration, the connection of the outlet mouth 26 to the outlet pipe 28 is effected by tilting the radial plane 32 of the turbine relative to the main direction 34 of fluid flow in the delivery pipe.

exit 28.

  The value e of the angle of inclination is chosen to correspond substantially to the inclination a of the configuration of the prior art (FIG. 1), but in the opposite direction, so as to obtain directly in the outlet pipe a

  air flow 36 substantially parallel to the main direction

  fluid flow blade 34 in the outlet pipe, that is to say substantially perpendicular to the inlet of the accessory (filter, exchanger, etc.) which will receive this air flow. The angle of inclination P can be between 0 and 15, from

preferably between 5 and 100.

  It is found in practice that, for a given angle, the desired results are obtained practically independently of the speed of rotation of the turbine, thereby ensuring constant performance whatever the

  operating speed of the motor-driven fan unit.

  This configuration has multiple advantages, due to the elimination of air rectifier blades: - simplification of the motor-fan unit both in design and in manufacture, with a corresponding saving in terms of manufacturing cost, - electrical power less to satisfy the ventilation performance, due to the reduction in pressure drop, - gain at acoustic level, the blades being sources of

  turbulence, therefore air flow noises.

Claims (3)

Claims   1. Motor-fan unit (10), in particular for the heating-air conditioning installation of a motor vehicle, comprising a housing of approximately cylindrical shape housing a centrifugal turbine (12) driven by a motor (16) and able to draw air axially surrounding by an air inlet and discharging it radially outwards, this housing further comprising a peripheral volute (24) enveloping with an increasing section the turbine and able to deflect tangentially and discharge the air flow thus produced towards a outlet pipe (28) extending in a main direction (32) of fluid flow, characterized in that the assembly formed by the turbine and the volute is disposed inclined relative to the outlet pipe, the radial plane (32) of the turbine forming an angle (f) with respect to the main direction (34) of flow in the outlet pipe, the direction and the angle of inclination being chosen so as to orient the e air flow (36) expelled by the volute substantially parallel to the main direction (34) of flow in the outlet pipe.   2. Motor-fan unit according to claim 1, character-   risé in that the assembly formed by the turbine and the volute is inclined on the opposite side to that of the air inlet (22) of the turbine.   3. Motor-fan unit according to claim 1, character-   laughed in that said tilt angle (P) is understood   between 0 and 15, preferably between 5 and 10.