Ventilation device provided with a volute-shaped casing

1. A ventilation device for an apparatus for a heating, ventilation and/or air-conditioning of a motor vehicle passenger space, comprising a fan wheel having blades mounted turning about an axis of rotation (A 1 ) inside a radially volute-shaped casing, the casing including an axial mouth for aspiration of air and a radial mouth for delivery of air which communicate with the inside of a volute-shaped compartment delimited by a peripheral wall of the casing, the peripheral wall of the casing moving progressively away from a periphery of the fan wheel from a volute tongue to a distal end (E 2 ) of the volute, the radial expansion of the volute being defined by an angle of expansion (a i ), wherein the initial angle of expansion (a 1 ) in a vicinity of the volute tongue is 1.5 times to 3 times greater than the final angle of expansion (a 2 ) in a vicinity of the distal end (E 2 ) of the volute, so that the peripheral wall of the casing moves more rapidly away from the blades at the start of the volute minimising turbulences generated at the volute tongue, and wherein the radial expansion of the volute is defined by the equation:

R

vi

=

(

R

t

+

d

tv

)

×

e

(

θ

i

×

tan

⁡

(

a

1

-

(

a

1

-

a

2

θ

max

)

×

θ

i

)

)

(

1

)

in which:

R vi is a radius of the volute at a determined point (E i ) of the volute,

R t is the outer radius of the fan wheel,

d tv is a minimum radial distance between an outer edge of the blades of the turbine and the volute tongue,

θ 1 is an angle defined by an initial end (E 1 ) of the volute and the determined point (E 1 ) of the volute about the axis of rotation (A 1 ),

a 1 is the initial angle of expansion of the volute,

a 2 is the final angle of expansion of the volute,

θ max is the volute angle which corresponds to the angle defined by the initial end (E 1 ) of the volute and the distal end (E 2 ) of the volute about the axis of rotation (A 1 ) and wherein the volute angle (θ max ) is between 290 and 315 degrees.

2. The ventilation device of claim 1 , wherein that the initial angle of expansion (a 1 ) is between 3.5 and 9 degrees.

3. The ventilation device of claim 1 , wherein that the final angle of expansion (a 2 ) is between 3 and 5 degrees.

4. The ventilation device of claim 1 , wherein that an axial section of the peripheral wall of the volute has a profile generally of “C”-shape.

5. The ventilation device of claim 4 , wherein that the radial delivery mouth has an axial section of rounded or ovalised profile so that an outlet section, which extends from the distal end (E 2 ) of the volute to the radial delivery mouth progressively forms a tube.

6. The ventilation device of claim 5 , wherein that an evolution of an axial expansion of the volute generally follows an evolution of the radial expansion of the volute.

7. The ventilation device of claim 6 , wherein that the volute tongue generally has an ovalised profile.

8. The ventilation device of claim 7 , wherein that an outer profile of the fan wheel, in an axial plane, is generally parallel with the axis (A 1 ) of the fan wheel.

9. The ventilation device of claim 8 , wherein that an inner circumferential edge of the volute is extended, on a side of the axial aspiration mouth, by a radial extension which covers a portion of the fan wheel and which delimits the axial aspiration mouth.

10. The ventilation device of claim 9 , wherein that the casing is made in a form of two half-shells, the half-shells being assembled one with the other in a joint plane perpendicular to the axis (A 1 ) of the fan wheel.

11. The ventilation device of claim 1 , wherein that the initial angle of expansion (a 1 ) is between 3.5 and 9 degrees, and the final angle of expansion (a 2 ) is between 3 and 5 degrees.