WO2003038285A1 - Motor fan system - Google Patents

Abstract

The invention relates to a motor fan system comprising: a motor; a motor support cover with a motor housing and a circular flange; a motor control unit; a cylindrical turbine which is rotated by the motor around an axis of rotation DELTA ; and an essentially-cylindrical scroll casing (10) which houses the turbine in the central part thereof. The aforementioned casing comprises: a first side (10a) containing a circular opening (13) which is intended to receive the motor support cover and which is more or less tangent to a scroll nose piece (11); a second side which is disposed opposite the first (10a) and which is provided with an air inlet; and a peripheral wall which surrounds the turbine (12) in a circumferential manner with one contour thereof having a radius that increases in relation to the axis of rotation DELTA of the motor, said peripheral wall beginning at the part thereof with the smallest radius at the scroll nose (11). The aforementioned circular opening (13) is centred around an axis DELTA ' which is offset in relation to axis of rotation DELTA of the motor such that, in the plane of the circular opening (13), the distance between the scroll nose (11) and centre DELTA ' of the circular opening (13) is greater than that between the scroll nose (11) and axis of rotation DELTA . In this way, a free space is cleared on the motor support cover on the flange surrounding the motor housing and, as a result, the same control unit can be mounted in a motor fan system that rotates clockwise or anticlockwise.

Description

Title of invention

MOTOR-FAN GROUP

Invention background

The invention relates to a motor-driven fan unit, in particular for a heating and / or air conditioning installation, in particular for a motor vehicle.

For such applications, it is known to produce a motor-fan unit comprising a scroll defining a scroll nose and a scroll outlet; a turbine housed in the volute to generate an air flow therein; a turbine drive motor aligned with the latter on an axis of rotation Δ; an engine support defining a flange surrounding an engine housing centered around the axis Δ and projecting axially relative to the volute, said engine support forming a cover for closing the volute on one side thereof; and a motor control module remote from the volute casing.

FIG. 21 is a very schematic view of the state of the art, showing a volute casing 10 having a contour 100d starting with a volute nose 11 and, on a first side 10a, a circular opening 130 intended to receive a engine support cover. The contour 100e of the circular opening 13 is centered on the axis of rotation Δ of a motor 14 and tangent to the volute nose 11.

In general, the scroll casing is of an approximately cylindrical shape comprising the first side 10a, defining the circular opening intended to receive the support for the motor, a second side opposite the first with an opening for an entry of air, and a peripheral wall enveloping a turbine 12 circumferentially with a contour having a radius which increases with respect to the axis of rotation Δ of the motor 14. The peripheral wall begins at its portion of smallest radius by the volute nose 11.

The motor support which also forms a cover for closing the volute comprises one. motor housing and a circular rim whose contour matches the circular opening 130 of the volute casing 10. A first object of the invention is to propose a new arrangement of the control module in a motor-fan unit which reduces the length of the electrical connections with the motor, source of unwanted electromagnetic radiation and which also allows easy disassembly and reassembly.

Another object of the invention is to propose a motor-fan group of small size.

In addition and almost systematically, a vehicle having a right-hand direction requires a motor-fan unit rotating in the opposite direction to that equipping a vehicle having a left-hand direction.

Consequently, in the case where the control module is integrated into the motor support, a control module is required for a motor-driven fan group rotating clockwise and another control module for a motor-driven fan group rotating in the direction counterclockwise.

Consequently, the production of two different types of control module complicates the manufacture of the motor-fan unit and increases the costs thereof.

Subject and summary of the invention

These aims are achieved by means of a motor-driven fan unit of the type defined at the head of this description and in which the circular opening is centered around an axis Δ offset from the axis Δ of rotation of the motor so that in the plane of the circular opening, the distance between the volute nose and the center of the circular opening Δ is greater than that between the volute nose and the axis of rotation Δ, so as to leave a free space on the edge surrounding the engine housing.

With this configuration of motor-fan unit comprising a volute casing having a circular opening which makes it possible to accommodate a standard motor support hood having a sufficient surface, it becomes possible to install a control module. Directly on the motor support hood .

This also becomes possible for a motor-fan group rotating clockwise as for a motor-fan group rotating anti-clockwise. Thus, the external side of the motor support is symmetrical with respect to the plane defined by the two axes Δ and Δl so that the support motor for a motor-fan group rotating clockwise is symmetrical by a simple rotation around the motor axis Δ, to the motor support for a motor-fan group rotating counterclockwise. The axis Δ can be offset in a direction perpendicular to the plane defining the volute outlet.

Preferably, the circular opening of the volute casing is substantially tangent to the contour of the volute in a region radially opposite the volute nose relative to the center Δ of the circular opening.

Advantageously, the volute nose penetrates inside the circular opening.

The scroll casing is formed by two superimposed elements, a first element delimiting the first side as well as a part of the peripheral wall and a second element delimiting the second side as well as the complementary part of the peripheral wall, the first and second elements. being hermetically assembled together by a fixing means and by a sealing bead.

According to one embodiment, the volute nose is formed entirely in the second element of the volute casing.

Thus, the first element of the volute casing comprises a housing making it possible to receive a part of the volute nose and in that the sealing bead is disposed. outside this accommodation.

The circular opening of the volute casing has lugs regularly distributed around its contour allowing bayonet mounting of the motor support cover.

According to another embodiment, a part of the volute nose belongs to the first element of the volute casing and a complementary part of the volute nose belongs to the second element of the volute casing.

The circular opening of the volute casing has pins regularly distributed around its contour except on a part in line with the volute nose.

However, the circular opening of the scroll casing may include pins regularly distributed around its contour with at at least one lug near the volute nose having a length less than the length of the other lugs.

The two elements of the scroll casing are molded from a synthetic material. The engine control module is arranged in the free space cleared on the flange surrounding the engine housing.

Advantageously, the free space released on the rim allows the mounting of a control module both in a motor-fan group rotating in a clockwise direction than in a motor-fan group rotating in a counter-clockwise direction.

The offset between the axes Δ and Δl is between 5 mm and 20 mm and preferably between 5 mm and 15 mm.

The motor-fan unit comprises two channels for circulating air for cooling the engine formed by a recess in the internal wall of the engine support cover, said channels extending laterally relative to the engine housing, in a plane C passing through the motor housing axis Δ.

Advantageously, the plane C defined by the channels is perpendicular to a plane of symmetry P on the outside of the motor support defined by the axes Δ and Δl.

According to one embodiment, the plane C defined by the channels forms an angle between -25 ° and + 25 ° relative to a plane M passing through the motor axis Δ and parallel to the plane of the volute outlet.

According to a particular mode, the plane C defined by the channels is merged with the plane M.

The motor-fan unit has three motor mounting studs uniformly distributed around the motor housing and one of which is located in a zone of smaller width, from the edge opposite to said zone of greater width at the plane of symmetry P, both others being positioned as close as possible to the canals.

Advantageously, the control module is housed between the two studs in the area of greatest width.

The engine support, the cooling channels and the engine connection pads are molded in one piece. The invention also relates to a heating and / or air conditioning installation for a motor vehicle, comprising a group motor-ventilator connected to a duct fitted with at least one air heating or cooling device.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood on reading the description given below, by way of indication but not limitation, with reference to the appended drawings, in which:

FIG. 1 is a very diagrammatic view of a heating and air conditioning installation for a motor vehicle, FIG. 2 is an elevation view of a motor-fan unit according to one embodiment of the invention,

FIG. 3 is a very schematic view of the scroll casing according to the invention,

FIG. 4 is a very schematic view of the scroll casing according to an embodiment of the invention,

FIG. 5 is a very schematic view of the scroll casing according to another embodiment of the invention,

FIG. 6 is a perspective view showing the structure of a scroll casing in accordance with the principle of FIG. 5 according to one embodiment,

FIGS. 7 and 8 are detailed views of FIG. 6,

FIG. 9 is a perspective view showing the structure of a scroll casing according to the principle of FIG. 5 according to another embodiment, - FIGS. 10 and 11 are detailed views of FIG. 9,

- Figure 12 is a side elevational view of a motor-fan unit rotating clockwise comprising an engine support according to one embodiment of the invention;

- Figure 13 is a side elevational view of a motor-fan unit rotating counterclockwise comprising an engine support according to one embodiment of the invention;

- Figure 14 is a very schematic view of the motor fan unit showing the motor support according to the principle of Figure 12; - Figure 15 is a very schematic view of the motor fan unit showing the motor support according to the principle of Figure 13;

- Figure 16 is a schematic view illustrating the axial symmetry resulting from the motor supports according to Figures 14 and 15; and

- Figures 17, 18, 19, 20 are very schematic views for variants of a motor-fan unit rotating clockwise and of a motor-fan group rotating anti-clockwise respectively, - Figure 21 is a very schematic view of a scroll casing according to the prior art.

Detailed description of embodiments of the invention

Different embodiments of the invention will be described below in the context of the application to a heating and / or air conditioning installation of a motor vehicle. A motor-driven fan assembly according to the invention can however be used for other applications requiring the generation of a flow of air or any other gas.

FIG. 1 very schematically shows part of an air vehicle heating and air conditioning installation which comprises, in a well-known manner, a motor-fan unit 1, known as a fan or blower, delivering an air flow 2 into an air distribution and treatment unit 3.

The air distribution box channel 3 brings this air flow 2 under pressure through an evaporator 4 of a refrigeration circuit (when the air conditioning function is present), a liquid heat exchanger radiator 5 traversed by the vehicle engine coolant and an optional electric radiator 6. In air conditioning mode, the air flow is deflected by flaps (not shown) in a passage 7 bypassing the radiator 5. Downstream of the radiators 5 and 6, the duct of the housing 3 distributes the air selectively according to the positions of the mixing and distribution flaps 8 to outlet outlets 9 in the passenger compartment of the vehicle.

The fan motor unit 1 comprises (FIGS. 1 and 2) a volute casing 10 inside which a turbine 12 is housed. The peripheral wall 10b (see FIG. 6) of the volute casing 10 as well as the part device 12a of the turbine 12 delimit a spiral volute whose section increases from a zone called “volute nose” 11 to an air outlet zone 10c.

On a first side 10a, the scroll casing 10 has a circular opening closed by a cover 20 forming a support for a motor 14 for driving the turbine 12. The motor 14 (shown diagrammatically in phantom in Figures 1 and 2 ) drives the turbine 12 in rotation about an axis of rotation Δ. The turbine 12 is mounted by radial arms on the motor output shaft 14a 14. The motor support cover 20 defines a housing 22 for the motor which projects laterally on the side 10a of the volute casing 10.

On a second side opposite side 10a, the scroll casing 10 has a central air intake opening 51 (see FIG. 6). When the turbine 12 is rotating, the air present in the volute casing 10 is expelled in the radial direction towards the duct of the air distribution casing 3, which has the effect of producing an axial suction of the air at from the central intake opening. The air sucked in and circulated by the turbine 12 is extracted from the volute casing 10 through the outlet 10c connected to the duct of the air distribution box 3. FIG. 3 shows the edge 10d of the volute and the outline 10e a circular opening 13 formed on the first side 10a of the volute casing 10, substantially tangent to the volute nose 11. The circular opening 13 is centered around an axis Δ offset from the axis of rotation Δ of the motor so that in the plane of the circular opening 13, the distance between the volute nose 11 and the center Δ of the circular opening is greater than that between the volute nose 11 and the axis of rotation Δ. Thus, for a given volute and for two circular openings of contours 10e and 100e substantially tangent to the volute nose 11, the surface of that having the center Δ (shown in solid line) is larger than that having the center Δ (shown in broken line). In addition, thanks to the eccentricity, the gain in surface area (hatched part) is mainly concentrated on one half of the opening which makes it more compact and therefore more useful. The axis Δ ^' can for example be offset with respect to the axis Δ in a direction perpendicular to the plane defining the volute outlet 10c. Consequently, and with reference to FIG. 2, a motor control module 30, which makes it possible to drive the motor 14 at a variable speed of rotation as a function of the desired air flow rate at the outlet of the volute casing 10, can now be mounted on the engine support cover 20 on the outside of the cover.

More specifically, the module 30 is mounted on a part of a flange 24 of the engine support cover 20 which surrounds the opening of the engine housing 22. The rim 24 has a circular contour 24a which adapts to the circular opening 13 formed on the first side 10a of the scroll casing 10. The closure of this opening 13 is carried out for example by mounting of the "quarter-of- tower "or bayonet of the engine support hood 20 on the first side 10a of the volute casing 10.

The axis of the motor housing 22 (which is of course coincident with the axis Δ of the motor and the turbine) is offset with respect to that of the contour 24a of the motor support cover 20. In this way, the flange 24 has a width variable and the control module 30 can be mounted in the area or free space 24b of the rim 24, of greater width. Sufficient space is thus provided for mounting the control module 30, while limiting the total size. Thus, the control module 30 is housed as close as possible to the motor 14 reducing the electrical connections and the space requirement, while allowing easy disassembly and reassembly of the control module 30 when necessary.

The control module 30 comprises a plate or printed circuit board (not shown) supporting a set of electrical and electronic components 31 and connectors for receiving a supply voltage and motor speed control signals and for supplying the supply necessary for the motor 14. The printed circuit board is fixed to a radiator (not shown) provided with cooling fins which penetrate inside the volute casing 10 in the vicinity of the periphery of the volute, and cannot interfere with the turbine 12 when the latter is rotating. Thus, effective cooling of the control module 30 is ensured by the air flow generated in the volute.

More particularly, FIG. 4 shows that the circular opening 13 formed on the first side 10a of the volute casing 10 is substantially tangent to the contour of the volute in an area 11 ^' radially opposite to the volute nose 11 with respect to the axis Δ in the plane of the circular opening 13. In this case, for a given volute casing, the edge of the engine support cover has a gain in usable surface area of more than '' about 30% compared to a rim of an engine support cover having an axis coincident with the axis of the engine.

According to another embodiment of the invention, shown in FIG. 5, the circular opening 13 extends beyond the volute nose 11. In other words, the volute nose 11 penetrates inside the opening 13 so that the surface available above the volute nose 11 can be used to increase the surface of the engine support cover.

For a circular opening 13 substantially tangent to the contour of the volute in a zone 11 ^′ radially opposite to the volute nose 11 and which also extends beyond the volute nose 11, the rim of the motor support cover has, for a given volute casing , a gain in area of more than about 40% compared to a rim of an engine support cover having an axis coincident with the axis of the engine.

Consequently, for a small volute, the surface above the volute nose makes it possible to mount a large motor support cowl, specially developed for large diameter turbines. Thus, a standard motor support cover can be mounted on volute casings of different sizes.

Figures 6 to 8 show the structure of a scroll casing 10 according to the invention, formed of two elements 40 and 50 superimposed. A first element 40 delimits the first side 10a as well as a part of the peripheral wall 10b. A second element 50 defines the second side which has a central opening 51 for air intake as well as the complementary part of the peripheral wall 10b. The first and second elements 40 and 50 are hermetically assembled together by a fixing means 45 and a sealing bead 42 and 52. Each element of the scroll casing is preferably molded in a synthetic material.

More particularly, the volute casing 10 of FIG. 6 defines a volute nose 11 which penetrates inside the circular opening 13. In addition, in the example of FIG. 6, the outline 10e of the circular opening 13 is substantially tangent to the contour of the volute in a zone 11 ^′ radially opposite to the volute nose 11. A part of the volute nose 11a is defined in the first element 40 of the volute casing 10 and its complementary part 11b is defined in the second element 50 of the volute casing 10. Furthermore, at the connection 60 between the two elements 40 and 50, a peripheral rib 42 is formed on the contour 41 of one of the elements (on the first element 40 in the example of FIGS. 7 and 8) and a groove 52 which cooperates with the rib 42 is formed on the contour 51 of the other element thus forming a sealing bead.

The two elements 40 and 50 are fixed to each other, by means of fixing 45 and polarization 46 projecting from the surface located on the peripheral wall 10b of the scroll casing 10 at the contours 41 and 51 of their connector 60. The means of fixing 45 are composed of complementary parts 45a and 45b fixed by screws or screw-nuts. The polarizing means 46 can be produced by a stud 46a cooperating with a hole 46b.

The circular opening 13 of the volute casing 10 comprises lugs 48 regularly distributed over its contour 10e except on a part 49 in line with the volute nose 11. The fact that the zone 49 above the volute nose 11 of the first element 40 is free of the lugs 48 allows this zone 49 to be removed from the mold in the same movement as the release from the top of the lugs 48. FIG. 6 shows that the same result can be obtained with at least one lug 48 ^' close to the volute nose 11 having a length less than the length of the other pins 48.

The lugs 48 on the contour 10e of the circular opening 13 allow the mounting of the engine support cover by a quarter-turn or bayonet system.

FIG. 9 shows another embodiment according to the invention for a volute casing 10 with a volute nose 11 which penetrates inside the circular opening 13. In addition, this opening 13 can be as it is shown in Figures 5 and 9, substantially tangent to the outline 10e of the volute in a zone 11 ^' radially opposite the volute nose lld.

In this embodiment, the volute nose lld is formed entirely in the second element 50 of the volute casing 10. In fact, as shown in FIGS. 9 to 11, the αe volute nose lld is completely incorporated in the second element 50 with a protruding part lie which engages in a housing 43 formed in the first element 40. In this case, as shown in FIGS. 10 and 11, the sealing bead between the two elements is arranged outside this housing 43. This sealing bead is formed by a peripheral rib 42 ^' situated on the contour 41 ^' of the first element 40 and a complementary groove 52 ^' situated on the contour 51 ^' of the second element.

The circular opening 13 of the volute casing 10 may include lugs 48 regularly distributed over its contour 10e to allow bayonet mounting of the engine support cover. Indeed, the first element 40 having no scroll nose can be removed from the mold without undercut.

FIG. 12 shows the motor-fan group 1 rotating clockwise and FIG. 13 shows the motor-fan group 1A rotating anti-clockwise. As in Figure 1 or 2, the fan motor group 1

(respectively 100) illustrated in Figure 12 has a volute 10 (110) inside which is housed the turbine 12 (120). On one of its sides 10a (100a), the volute has an opening closed by a cover 20 (200) forming a support for the motor 14 (140) driving the turbine 12 (120). The motor 14 (140) and the turbine 12 (120) are coaxial with axis Δ. The turbine is mounted on the output shaft 14a (140a) of the engine 14 (140). The motor support 20 (200) delimits the housing 22 (220) for the motor which projects axially or laterally on the side 10a (110a) of the volute. The side of the volute opposite side 10a (110a) has the central air intake opening (51). The air sucked in and circulated by the turbine is extracted from the volute 10 (100) by the outlet 10c (110c) connected to the air distribution duct.

According to the invention and as illustrated in FIGS. 12, 13, 14 and 15, the motor support 20 (200) of the motor-fan unit 10 (100) rotating clockwise (respectively anti-clockwise) is centered around d 'an axis Δl offset with respect to the axis Δ of the engine housing. The offset of the two axes Δ and Δl defined for the rim 24 (240) a variable width comprising a zone 24b (240b) of greater width. The two axes Δ and Δl define a plane of symmetry P for the outer side of the engine support 20 (200). Preferably and in this variant of the invention, in the plane of the motor support, the distance between the volute nose 11 and the axis Δl is greater than that between the volute nose 11 and the axis Δ. The offset between the axes Δ and Δl may for example be between 5 mm and 20 mm and preferably between 5 mm and 15 mm thus freeing up the additional area or free space 24b on the flange 24 (240) surrounding the motor housing 22 ( 220).

In the example of FIGS. 14 and 15, the plane of symmetry P is substantially perpendicular to the plane defining the volute outlet 10c (100c).

The cooling of the motor 14 (140), and in particular of its part comprising brushes 500, located in the vicinity of the bottom of the motor housing 22 (220), is ensured by taking air from the volute 10 (100). The cooling air is brought to the bottom of the engine housing

22 (220) by cooling channels 410, 420 formed by recesses in the internal wall of the engine support cover 20 (200).

On the outside, these channels 410, 420 join the rim 24 (240), in the vicinity of its periphery 24a (240a), to the wall which defines the motor housing in the vicinity of the bottom thereof. The two channels 410, 420 are diametrically opposite and define a plane C substantially perpendicular to the plane of symmetry P. In other words, the plane C is coincident with a plane M passing through the motor axis Δ and parallel to the plane defined by the output of volute. In this case, the surface available on this motor support is maximum.

Advantageously, the axis of the motor Δ is situated in the plane C defined by the channels 410, 420 so that the channels can open out at the level of the brushes 500 situated in two opposite zones of the motor 14 (140), the latter being mounted for this purpose symmetrically with respect to the cooling channels.

The engine 14 (140) is provided with fixing lugs (not shown) which are inserted in housings formed in the engine support cover 20 (200). As the figures show, the engine support cover comprises three stamped parts or studs 25a, 25b, 25c (250a, 250b, 250c) uniformly located around the engine housing 22 (220), one stud 25a (250a) of which is located in an area 24c. (240c) less width of the rim 24 (240) opposite the zone or free space 24b (240b) of greater width at the level of the plane of symmetry P, the other two 25b, 25c (250b, 250c) being positioned as close as possible to the cooling channels 410, 420. The engine is fixed by screws or screw-nuts 27 (270) which pass through the engine fixing lugs and the fixing studs 25a, 25b, 25c (250a, 250b, 250c).

Thus, the symmetry on the outside of the engine support cover 20 (200) is preserved, knowing that the angle between the studs two by two is approximately 120 ° and that one of these studs 25a (250a) is crossed by the plane of symmetry P.

The fact that one of the studs is located in the middle of the zone 24c (240c) of smaller width of the rim 24 (240) makes it possible to keep a surface of fairly uniform width in the zone 24b of the rim of greater width. FIG. 16 shows that the particular locations of the fixing pads 24a, 25b, 25c and the cooling channels 41, 42 on the outside of a motor support cover 20 of a motor-fan unit 10 rotating in a clockwise direction is symmetrical with respect to the plane of symmetry P. Similarly, for an engine support cover 200 of a motor-fan unit 100 rotating in an anti-clockwise direction. In addition, the two motor supports 20 and 200 are symmetrical by a rotation of

180 ° around the motor axis Δ. Thus, the volume available on the outside is identical for the two engine support covers 20 and 200.

Consequently, the same control module 30, which makes it possible to control the drive of the variable speed motor as a function of the desired air flow rate at the outlet of the volute, can be mounted both on the motor support cover 20 of a motor-fan unit 10 rotating clockwise than that of a motor-fan group 100 rotating counter-clockwise. More specifically, the module 30 is mounted on the zone of the rim 24 (240) of greater width.

The control module 30 includes a printed circuit board (not shown) on which are arranged electronic components connected together by electrical tracks. The printed circuit board and electronic components are thermally coupled with an aluminum radiator (not shown). Furthermore, the control module 30 is provided with a cover made of synthetic material. The homogeneous width of the area or free space 24b (240b) of the rim 24 (240) of greater width makes it possible on the one hand to produce a printed circuit with an optimal architecture for the electrical tracks thus reducing the losses by Joule effect, and on the other hand greatly reduces the cost of manufacturing a printed circuit with a shape that fits best in a rectangle making it possible to manufacture more circuits in the same blank.

The module 30 is connected by connectors and conductors (not shown) to a supply voltage source, to a control unit of the heating and air conditioning installation, and to the motor 14 (140).

According to an alternative embodiment, FIG. 17 illustrates a motor-fan unit 10 rotating clockwise comprising a motor support 20. In this example, the plane C defined by the cooling channels 410 and 420 is always perpendicular to the plane of symmetry P defined by the axes Δ and Δ 1. On the other hand, the angle oc between the plane C and a plane M passing through the motor axis Δ and parallel to the plane defining the volute output 10c is between 0 ° and 25 ° .

Similarly, FIG. 18 illustrates a motor-fan unit 100 rotating counter-clockwise comprising a motor support 200 symmetrical by a simple rotation about the axis Δ to the motor support 20 of the motor-fan group 10 rotating in the direction schedule.

Thus, the same control module can be mounted both on the motor support 20 of the motor-fan unit 10 rotating clockwise as on the motor support 200 of the motor-fan group 100 rotating anti-clockwise.

Figures 19 and 20 illustrate another alternative embodiment in which the angle <χ between the plane C passing through the cooling channels and the plane M passing through the motor axis Δ is now between -25 ° and 0 °.

The advantages linked to the standardization of the reference of the module are the identity of all the components of the module like the aluminum alloy radiator whose tooling is expensive as well as the plastic cover requiring a specific mold and the assembled printed circuit. . This also results in a simplification for the design office designer who implements a single module. The risk of error in the event of a different module disappears.

Another important advantage is the fact that during CAD layout where the cases of creation of symmetrical parts are common, a simple image symmetry is enough to conceptualize a model for a right hand drive from a model for a right hand drive. left. Thus, a great gain in validation is achieved without the need to do a complete aerolic study. A particular advantage of the invention lies in the fact that the cooling channel or channels are defined by reliefs of the engine support cover and can be produced in a single piece with the latter, by molding, as are the particular reliefs in level of the air inlets in the channels and the engine mounting studs.

Claims

1. Motor-fan unit (1) comprising: - an engine (14), - an engine support cover (20) with housing (22) engine and circular flange (24), - an engine control module (30), - a cylindrical turbine (12) driven in rotation by the motor (14) around an axis of rotation Δ, and - an approximately cylindrical scroll casing (10) housing in its central part the turbine (12) and comprising a first side (10a) with a circular opening (13) intended to receive the engine support cover (20), the circular opening (13) being substantially tangent to a volute nose (11), a second side opposite the first (10a) with an air intake opening (51), and a peripheral wall (10b) enveloping the turbine (12) circumferentially with a contour having an increasing radius relative to the rotation tax Δ of the motor (14), the peripheral wall (10b) starting at its smallest radius with the volute nose (11), characterized in that; the circular opening (13) is centered around an axis Δ ^' offset from the axis of rotation Δ of the motor (14) so that in the plane of the circular opening (13), the distance between the volute nose (11) and the center Δ of the circular opening (13) is larger than that between the volute nose (11) and the axis of rotation Δ, so as to release on the cover (20) motor support a free space (24b) on the flange (24) surrounding the motor housing (22). 2. motor-fan unit (1) according to claim 1, characterized in that the axis Δ is offset in a direction perpendicular to the plane defining the volute outlet (10c). 3. fan motor unit (1) according to claim 1, characterized in that the circular opening (13) of the volute casing (10) is substantially tangent to the contour of the volute in a zone (11 ^' ) radially opposite to the volute nose (11) relative to the center Δ of the circular opening (13). 4. motor-fan unit (1) according to any one of claims 1 to 3, characterized in that the volute nose (11) penetrates inside the circular opening (13). 5. motor-fan unit (1) according to any one of claims 1 to 4, characterized in that the scroll casing (10) is formed of two superimposed elements, a first element (40) delimiting the first side (10a ) as well as a part of the peripheral wall (10b) and a second element (50) delimiting the second side as well as the complementary part of the peripheral wall (10b), the first and second elements (40, 50) being hermetically assembled between them by a fixing means (45) and by a sealing bead (42, 52). 6. motor-fan unit (1) according to claim 5, characterized in that the volute nose (lld) is formed entirely in the second element (50) of the volute casing (10). 7. motor-fan unit (1) according to claim 5 or claim 6, characterized in that the first element (40) of the volute casing (10) comprises a housing (43) for receiving a part of the volute nose (lie) and in that the sealing bead (42 ^' , 52) is disposed outside of this housing (43). 8. fan motor unit (1) according to any one of claims 1 to 7, characterized in that the circular opening (13) of the volute casing (10) comprises lugs (48) regularly distributed over its contour ( 10e) allowing bayonet mounting of the hood (20) engine support. 9. fan motor unit (1) according to claim 5, characterized in that a part of the volute nose (lia) belongs to the first element (40) of the volute casing (10) and a complementary part of the volute nose (11b) belongs to the second element (50) of the scroll casing (10). 10. Motor-fan unit (1) according to claim 9, characterized in that the circular opening (13) of the scroll casing (1) comprises lugs (48) regularly distributed over its contour except on a part (49) in line with the volute nose (11). 11. motor-fan unit (1) according to claim 9, characterized in that the circular opening (13) of the scroll casing (10) comprises lugs (48 ^' , 48) regularly distributed over its contour with at least one lug (48) near the volute nose (11) having a length less than the length of the other lugs (48). 12. motor-fan unit (1) according to any one of claims 1 to 11, characterized in that the two elements (40, 50) of the scroll casing (10) are molded in a synthetic material. 13. motor-fan unit (1) according to any one of claims 1 to 12, characterized in that the control module is arranged in the free space (24b) cleared on the flange (24) surrounding the motor housing ( 22). 14. motor-fan unit (1) according to any one of claims 1 to 13, characterized in that the free space (24b) cleared on the flange (24) allows the mounting of a control module (30) both in a motor-fan unit (10) rotating clockwise as in a motor-fan group (100) rotating anti-clockwise. 15. Fan motor unit according to any one of the preceding claims, characterized in that the offset between the axes Δ and Δl is between 5 mm and 20 mm. 16. Fan motor unit according to claim 15, characterized in that said offset is between 5 mm and 15 mm. 17. Motor-fan unit according to any one of the preceding claims, characterized in that it comprises two channels (410, 420) for circulation of the engine cooling air formed by a recess in the internal wall of the engine support cover. (20; 200), said channels extending laterally relative to the motor housing (22; 220), in a plane C passing through the axis of the motor housing Δ. 18. motor-driven fan unit according to claim 17, characterized in that the plane C defined by the channels (410, 420) is perpendicular to a plane of symmetry P on the outside of the motor support (20; 200) defined by the axes Δ and Δl. 19. Motor-fan unit according to any one of claims 17 or 18, characterized in that the plane C defined by the channels (410, 420) makes an angle between -25 ° and + 25 ° relative to a plane M passing through the motor axis Δ and parallel to the plane of the volute outlet. 20. Fan motor unit according to claim 19, characterized in that the plane C defined by the channels (410, 420) is coincident with the plane M, (a = 0 °). 21. Motor-fan unit according to any one of claims 1 to 20, characterized in that it comprises three mounting pads (25a, 25b, 25c; 250a, 250b, 250c) of the motor uniformly distributed around the motor housing ( 22; 220) and one of which (25a; 250a) is located in a zone (24c; 240c) of smaller width, from the edge opposite to said zone (24b; 240b) of greater width at the level of the plane of symmetry P., the other two (25b, 25c; 250b, 250c) being positioned as close as possible to the channels (410, 420). 22. motor-fan unit according to claim 21, characterized in that the other two three fixing pads (25b, 25c; 250b, 250c) of the motor are positioned as close as possible to the channels (410, 420). 23. Motor-fan unit according to claim 22, characterized in that the control module (30) is housed between the two studs (25b, 25c; 250b, 250c) in the free space (24b; 240b) of greater width. 24. Motor-fan unit according to any one of claims 17 to 23, characterized in that the engine support cover (20; 200), the cooling channels (410, 420) and the engine connection pads are molded in one single piece. 25. A heating and / or air conditioning installation for a motor vehicle, characterized in that it comprises a motor-fan unit (1) according to any one of claims 1 to 23 connected to a duct (3) provided with at minus a heating (5, 6) or air cooling (4) device.