ELECTRIC FAN

Abstract

 An electric ventilator comprises an axial impeller comprising a hub (101) having a cup-shaped structure defined by a bottom part (102), which is transverse to an axis of rotation (R) of the impeller, and a side wall (103), which extends axially from the bottom part (102); the impeller comprises a disc-shaped element (109), integral with the hub and disposed on the opposite side of the side wall with respect to the bottom part; the disc-shaped element is spaced from the bottom part of the hub to delimit a gap (110) therewith; the bottom part (102) is provided with a plurality of holes (106) defining a first passage between the inside of the cup-shaped structure and the gap (110); the hub and the disc-shaped element delimit a second passage or mouth (112) between the gap (110) and the outside of the cup-shaped structure.

Description

[0001] This invention relates to an electric ventilator intended for motor vehicles and other automotive applications for removing heat from radiating bodies and the like.

[0002] The use of electric ventilators is becoming more and more frequent in the automotive sector to remove heat from radiating bodies designed to cool vehicle systems, in particular when the dynamics of the vehicle are unable to provide an adequate flow of air.

[0003] Normally, electric ventilators comprise an electric motor for driving the impeller, an impeller and what is known as a "duct" which supports the motor and allows installing the electric ventilator where required; the assembly made up of the electric ventilator and the corresponding duct is also called ventilating unit or module.

[0004] There is a growing market demand for electric ventilating units equipped with motors having power ratings greater than or equal to one kilowatt, for example, for trucks, earth moving machinery, buses and motor cars.

[0005] At the same time, the market also requires electric ventilators with longer and longer working lives, up to 30000 hours and over for certain applications.

[0006] The structure of the electric motor comprises a casing, either sealed or open, which houses an electric motor with a conductive winding and, where necessary, electronic drive circuitry.

[0007] The winding has an electrical current flowing in it and this, through the Joule effect, produces heat which propagates to the entire winding and to adjacent parts of the electric machine.

[0008] Considering that the life of the electric ventilator in general, and of its components in particular, decreases as the operating temperature increases and that the operating temperature increases with the power output requirement, there is a need for the electric ventilator to reduce operating temperatures through more efficient cooling (all other conditions being equal, for example, the same dimensions and the same electronic components) if its working life is to be significantly increased.

[0009] In this context, our intention is to propose an electric ventilator capable of meeting the above mentioned need.

[0010] More specifically, this invention has for an aim to provide an efficiently cooled electric ventilator even for relatively high power ratings and to increase the working life thereof.

[0011] This aim is achieved by an electric ventilator comprising an impeller and an electric motor for driving the impeller.

[0012] The impeller comprises a hub having a cup-shaped structure defined by a bottom part, which is transverse to an axis of rotation of the impeller, and a side wall, which extends axially from the bottom part.

[0013] The bottom part comprises a radially internal, central portion, a radially external, outer portion and an intermediate portion for connecting the central portion and the outer portion to each other.

[0014] The impeller comprises a plurality of blades extending radially from the side wall of the hub and a disc-shaped element that is integral with the hub and disposed on the opposite side of the side wall with respect to the bottom part. The disc-shaped element is spaced from the bottom part of the hub to delimit an annular gap therewith.

[0015] The bottom part of the hub is provided with a plurality of holes defining a first passage between the inside of the cup-shaped structure and the annular gap. The hub and the disc-shaped element delimit a second passage or mouth between the gap and the outside of the cup-shaped structure.

[0016] Preferably, the maximum diameter of the disc-shaped element is greater than the maximum diameter of the side wall.

[0017] Preferably, the disc-shaped element comprises a curved peripheral surface with concavity facing towards the side wall and the blades of the axial impeller.

[0018] Preferably, the holes are made in the intermediate portion of the bottom part of the hub.

[0019] Preferably, the disc-shaped element is integral with the central portion or the outer portion of the bottom part of the hub.

[0020] Preferably, the central portion is spaced outwards, away from the outer portion of the cup-shaped structure along the axis of the impeller, in particular when the disc-shaped element is integral with the central portion of the bottom part.

[0021] Preferably, the axial impeller comprises a plurality of blades, disposed in the gap. The bottom part of the hub, the blades in the gap and the disc-shaped element define a centrifugal impeller which has an axial inlet defined by the holes in the central portion of the hub (that is to say, by the first passage) and a radial outlet defined by the second passage. Preferably, the blades of the centrifugal impeller extend from the central portion to the outer portion of the bottom part of the hub.

[0022] Preferably, the blades of the centrifugal impeller are made as a single part with the hub or with the disc-shaped element.

[0023] The electric motor comprises a thermally conductive casing, a stator and a rotor, both fitted in the casing, and a shroud that is coupled to the casing to form an enclosure for the stator and the rotor. The impeller is coupled to the rotor through the bottom part of the hub and the motor is at least partly housed in the hub of the impeller, inside the cup-shaped structure. The casing comprises a front wall that is fitted in the cup-shaped structure and faces the bottom part of the hub, and a side wall that is surrounded at least partly by the side wall of the hub. The electric motor comprises a plurality of heat dissipating fins formed in the front wall and facing towards the bottom part of the hub. The dissipating fins are shaped in such a way as to define channels for conveying air towards the holes in the bottom part of the hub.

[0024] Other features and advantages of the electric ventilator are more apparent in the exemplary, hence non-limiting description of a preferred but nonexclusive embodiment of an electric ventilator comprising the impeller. The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without limiting the scope of the invention and in which:

• Figure 1 is a schematic side view illustrating an application of an electric ventilator according to this disclosure in a first operating condition;
• Figure 2 is a schematic side view illustrating an application of an electric ventilator according to this disclosure in a second operating condition;
• . Figure 3 illustrates an embodiment of an impeller according to the disclosure in a schematic perspective view;
• Figure 4 illustrates the impeller of Figure 3 in a schematic side view;
• Figure 5 illustrates the impeller of Figure 3 in a schematic, exploded perspective view;
• Figure 6 illustrates the impeller of Figure 3 in a schematic, exploded perspective view;
• Figure 7 illustrates a detail of the impeller of Figure 3 in a schematic plan view;
• Figure 8 illustrates an embodiment of an impeller according to the disclosure in a schematic perspective view;
• Figure 9 illustrates the impeller of Figure 7 in a schematic side view;
• Figure 10 illustrates an electric ventilator according to the disclosure in an exploded perspective view;
• Figure 11 illustrates a portion of the electric ventilator of Figure 10 in a schematic perspective view with some parts removed for greater clarity;
• Figure 12 illustrates a portion of the electric ventilator of Figure 10 in a schematic cross section.

[0025] With reference to the accompanying drawings, the numeral 1 denotes a ventilating unit or module.

[0026] The unit 1, hereinafter described only insofar as necessary for understanding this invention, essentially comprises an axial impeller 100, an electric motor 200 for driving the impeller and a duct 300 for supporting the electric motor 200.

[0027] The electric motor 200 and the impeller 100 together define an electric ventilator which the duct 300 allows installing in a destination application, for example, in a heat exchanger or on a radiator 400 to remove heat from it.

[0028] In the embodiment illustrated by way of example, the electric motor 200 is a brushless, internal rotor motor comprising electronic drive circuitry also integrated in it.

[0029] As illustrated, the impeller 100 comprises a hub 101 for coupling to the motor 200.

[0030] The hub 101 has a cup-shaped structure defined by a bottom part 102, transverse to an axis of rotation R of the impeller, and by a side wall 103 extending axially from the bottom part 102.

[0031] The part 102 comprises a radially internal, central portion 102a, a radially external, outer portion 102b and an intermediate portion 102c for connecting the central portion 102a and the outer portion 102b to each other.

[0032] The part 102 and the wall 103 are joined along a rounded edge 104 provided with exhaust holes 105 for removing any impurities that may be present inside the hub 101.

[0033] The part 102 is provided with a plurality of holes 106 formed in particular in the intermediate portion 102c. The holes 106 define arms 107 which, in the hub 101, preferably constitute elastoplastic blades of the kind described in application WO2017021935 which is incorporated herein by reference for completeness of description.

[0034] In the embodiment illustrated for example in Figures 3 to 7, the central portion 102a is spaced outwardly away from the outer portion 102b of the cup-shaped structure along the axis of rotation R of the impeller.

[0035] In the example illustrated, the intermediate portion 102c is substantially conical. In alternative embodiments not illustrated, the intermediate portion 102c is orthogonal to the axis of rotation R of the impeller 100.

[0036] The impeller 100 comprises blades 108 that extend radially from the side wall 103 of the hub 101 and are made as a single part therewith.

[0037] As illustrated, the impeller 100 comprises an element 109 that is integral with the hub 101. The element 109 is in the form of a plate or disc or the like and is disc shaped.

[0038] In the preferred embodiments illustrated, the element 109 is circular.

[0039] In alternative embodiments not illustrated, the element 109 is polygonal and may have the shape of a regular polygon.

[0040] The element 109 defines a protective cover placed over the holes 106 and is hereinafter called disc-shaped element 109.

[0041] The disc-shaped element 109 is coaxial with the hub 101 and, more specifically, with the side wall 103 thereof.

[0042] In the embodiments illustrated by way of example, the disc-shaped element 109 has a maximum diameter D that is greater than the maximum diameter d of the side wall 103.

[0043] In alternative embodiments not illustrated, the maximum diameter D of the disc-shaped element 109 is substantially the same as the maximum diameter d of the side wall 103.

[0044] The disc-shaped element 109 is disposed on the opposite side of the side wall 103 with respect to the bottom part 102 and is spaced from the bottom part 102 so as to delimit a gap 110 therewith.

[0045] The gap 110 is annular and extends from the central portion 102a of the part 102 to the side wall 103 of the hub 101.

[0046] The axial width of the gap 110, that is to say the width measured along the axis R, depends on the cooling requirements of the application (usually a few millimetres, for example, between 1 mm and 20 mm, preferably between 2 mm and 10 mm).

[0047] The holes 106 define a passage between the inside of the cup-shaped structure of the hub 101 and the gap 110.

[0048] The hub 101 and the disc-shaped element 109 delimit a substantially annular passage or mouth 112 between the gap 110 and the outside of the cup-shaped structure, that is, towards the outside of the hub 101 itself. The disc-shaped element 109 comprises a curved peripheral surface 113 with concavity facing towards the side wall 103 and the blades 108.

[0049] Thus, the mouth 112 faces towards the side wall 103.

[0050] In the embodiment illustrated in Figures 3 to 6, the disc-shaped element 109 is integral with the central portion 102a.

[0051] Illustrated by way of example in Figure 6 is a fastening mechanism 114 for locking the disc-shaped 109 to the central portion 102a of the hub 101.

[0052] In the embodiment illustrated in Figures 7 to 10, the disc-shaped element 109 is integral with the outer portion 102b.

[0053] Preferably, the disc-shaped element 109 is integral with only one between the central portion 102a and the outer portion 102b, so that the arms 107 are free to apply a vibration damping action as described in the aforementioned application WO2017021935.

[0054] With reference to Figures 8 to 12, it should be noticed that the impeller 100 comprises a plurality of blades 115 which are disposed in the gap 110.

[0055] In the example illustrated, the blades 115 are of the "backward" type, while in alternative embodiments not illustrated, they may be of the "forward" or "radial" type, based on the application of the ventilating unit 1.

[0056] As illustrated, the blades 115 extend preferably between the central portion 102a and the outer portion 102b of the bottom part 102 of the hub 101.

[0057] With reference in particular to Figure 11, it should be noted that the blades 115, in the example illustrated, comprise blades 115a that extend from the central portion 102a to the outer portion 102b up to the maximum diameter of the bottom part 102.

[0058] The blades 115 comprise blades 115b that are shorter than the blades 115a and do not extend on the whole of the intermediate portion 102c of the bottom portion 102.

[0059] In alternative embodiments not illustrated, the blades 115, 115a and/or 115b may extend beyond the edge of the bottom part 102, even as far as the maximum diameter D of the disc-shaped element 109.

[0060] In the example illustrated, the blades 115a each extend directly from and/or at an arm 107.

[0061] In the example illustrated, the blades 115a are made as a single part with the hub 101 and the disc-shaped element 109 is joined to the hub 101 by the blades 115.

[0062] In alternative embodiments not illustrated, the blades 115 are made as a single part with the disc-shaped element 109.

[0063] In embodiments not illustrated, the impeller 100 of Figures 3 to 7 may also be provided with the blades 115 in the gap 110.

[0064] The bottom part 102 of the hub 101, the blades 115 and the disc-shaped element 109 define a centrifugal impeller 116 having an axial inlet, defined by the passage 111, that is, by the holes 106, and a radial outlet, defined by the passage or mouth 112.

[0065] As illustrated for example in Figure 12, the impeller 100 comprises vanes 117 inside the hub 101 which, in use, as described in more detail below, generate a whirling air motion around the motor 200 which is at least partly housed in the hub 101.

[0066] With reference to Figure 12, the vanes 117 are of substantially known type and extend predominantly axially and radially.

[0067] In the embodiment illustrated in Figures 6 and 7, the impeller 100 comprises vanes 118 inside the hub 101 which, in use, generate around the motor 200, which is at least partly housed in the hub 101, a whirling air motion also having an axial component.

[0068] The vanes 118 extend predominantly axially and in a direction that is inclined to a tangential direction at a leading angle between 5° and 45°, preferably between 10° and 20°.

[0069] In an embodiment not illustrated, the vanes 118 are straight. In the preferred embodiment illustrated, the vanes 118 have a wing profile with a leading angle between 5° and 45°, preferably between 10° and 20°.

[0070] The motor 200 comprises a thermally conductive casing 201, for example, made of aluminium or other metal, and a thermally conductive shroud 202, for example, made of aluminium or other metal, coupled to the casing 201 to form an enclosure which, in the example illustrated, is sealedly closed. The motor 200 comprises a stator 203, a rotor and electronic drive circuitry, not illustrated, housed in the closed enclosure.

[0071] The casing 201 comprises a front wall 204 that is fitted in the cup-shaped structure of the hub 101 and faces the bottom part 102 of the hub 101; and a side wall 205 that is surrounded at least partly by the side wall 103 of the hub 101.

[0072] The electric motor 200 comprises a plurality of heat dissipating fins 206 formed in the front wall 204 and facing towards the bottom part 102 of the hub 101.

[0073] The fins 206 are shaped in such a way as to define channels 207 for conveying air from the side wall 205 of the casing towards the holes 106 in the bottom part 102 of the hub 101.

[0074] The fins 206 are shaped in such a way that the air is taken in and accompanied towards the centre of the casing, where a radiused surface 208, also preferably formed in the front wall 204 of the casing 201, directs it axially towards the inlet 106 of the centrifugal impeller 116.

[0075] In use, normally, the heat exchanger 400 is located on the intake side of the impeller 100 and the flow sucked in is labelled F1.

[0076] In conditions where a vehicle is stationary or running at low speed, illustrated in Figure 1, the impeller 100 produces a higher pressure in the rear part of the motor 200, hence the air makes its way between the motor 200 and the hub 101 of the impeller to escape through the front holes 106, thereby defining a cooling flow F2.

[0077] The centrifugal impeller 106 contributes to sucking in the flow F2 in that, through the holes at the front of the hub, it takes in the air entering the hub of the impeller 100 and lets it out in the radial direction.

[0078] It is important to note that even the embodiment without the blades 115, 115a, 115b also produces a centrifugal effect solely through the frictional forces created by the air passing between the cover and the bottom part of the impeller hub, which are spaced a few millimetres apart, thus contributing to sucking in the flow F2.

[0079] With reference to dynamic conditions, illustrated for example in Figure 2, where the electric ventilator is subjected to a main flow F3 due to the forward movement of the vehicle, the following may be noted.

[0080] The peripheral portion of the disc-shaped element with concavity facing towards the hub is configured to produce, together with the geometry of the hub itself, in particular at its outside diameter, a "diffuser" facing in the same direction as the air entering the impeller 100. This design produces a Venturi suction effect which pulls air in through the mouth 112 by way of the holes 106, thus contributing to the flow F2.

[0081] The main flow F3 creates a negative pressure at the mouth 112 so the motor cooling air also circulates under dynamic conditions, in the same way as it does under static conditions.

[0082] Compared to a situation without the cover, the dynamics of the vehicle in any case help the motor cooling air to circulate by pulling the air in at the outlet of the gap.

[0083] When the vehicle is travelling at high speed, for example, higher than 120 Km/h, the impeller does not act as a suction element, since the dynamics of the vehicle push in more air than the electric ventilator can manage. Under these conditions, the electric ventilator, instead of being a means of suction, becomes a resistance and the pressure immediately downstream of the exchanger is not negative, but positive. At high speed, therefore, in the absence of the disc-shaped element, the direction of the flow F2 would be inverted. In practice, at a certain speed, if the disc-shaped element were not present, the flow F2 would be zeroed and the motor cooling effect that the flow F2 provides would be cancelled. Advantageously, the disc-shaped element and the gap promote the circulation of the cooling air which flows along the motor casing in the same direction at all times, without ever stopping, whatever the speed of the vehicle.

[0084] The fins on the front wall of the casing increase the heat exchange surface of the casing by 40%, thus enhancing the cooling effect that the system has on the electric motor.

[0085] The preferred shape of the fins allows the air to be pulled in towards the holes in the hub, forcing it to also flow along the front wall of the casing at the stator windings.

[0086] The holes in the bottom part of the hub are preferably at the centre, not only because of how the centrifugal impeller works but also because they force the air to touch the casing at the stator windings, which produce up to 50% and more of the heat generated by the motor.

[0087] The vanes provided inside the hub direct the air flow and give it a tangential component which is added to the axial component and increases the coefficient of heat exchange between the motor and the air, hence improving the cooling effect.

[0088] If the vanes are not disposed radially but at an angle of incidence, optimized with CFD, relative to the tangent, the vanes push the air also with a centripetal speed component.

[0089] In particular, the centripetal component pushes the air towards the centre of the casing, into the air conveying channels, if provided, and towards the holes in the bottom part of the hub, thus contributing to the circulation F2.

[0090] In the even more advanced case in which the vanes in the hub have a wing profile, resistance to forward movement is reduced, thus improving the overall performance and efficiency of the impeller, in particular in removing heat from the motor.

[0091] This solution allows obtaining a better cooling effect on the motor compared to prior art solutions because it creates a greater air flow at a greater speed. This air flow always enters the gap between motor and hub on the opposite side with respect to the heat exchanger, hence at the lowest temperature possible. Furthermore, the cooling air always circulates in the same direction, under all vehicle operating conditions.

[0092] As stated, the disc-shaped element constitutes a cover for the holes in the hub and, besides the fluid dynamic function mentioned, prevents dust and other extraneous bodies from entering the hub.

[0093] The solution described therefore, through an optimized, forced convection cooling system allows reducing the operating temperatures of the motor components/electronic circuits of the electric ventilator, thereby increasing their working lives. The heat is transferred from the motor casing to the air between the motor itself and the impeller hub and is removed from there by the external air drawn in from the back of the motor at the lower ambient temperature available there.

Claims

1. An electric ventilator comprising an impeller (100) that comprises a hub (101) having a cup-shaped structure defined by a bottom part (102), transverse to an axis of rotation (R) of the impeller, and by a side wall (103) extending axially from the bottom part (102), the impeller comprising a plurality of first blades (108) extending radially from the side wall of the hub and a disc-shaped element (109) that is integral with the hub and is disposed on the opposite side of the side wall with respect to the bottom part (102), the disc-shaped element being spaced from the bottom part and delimiting a gap (110) with the bottom part,
the bottom part (102) comprising a radially internal, central portion (102a), a radially external, outer portion (102b) and an intermediate portion (102c) for connecting the central portion (102a) and the outer portion (102b) to each other, the bottom part (102) being provided with a plurality of holes (106) defining a first passage between the inside of the cup-shaped structure and the gap (110), the hub and the disc-shaped element delimiting a second passage or mouth (112) between the gap (110) and the outside of the cup-shaped structure, the electric ventilator comprising an electric motor (200) for driving the impeller (100) and comprising a thermally conductive casing (201), a stator (203) and a rotor, both fitted in the casing (201), and a shroud (202) that is coupled to the casing (201) to form an enclosure for the stator and the rotor, the impeller (100) being coupled to the rotor through the bottom part (102) of the hub (101), the motor (200) being at least partly housed in the hub (101), the casing comprising a front wall (204) that is fitted in the cup-shaped structure of the hub (101) and faces the bottom part (102) of the hub, and a side wall (205) surrounded at least partly by the side wall (103) of the hub, the electric motor (200) comprising a plurality of heat dissipating fins (206) formed in the front wall (204) and facing towards the bottom part (102) of the hub (101), the dissipating fins (206) being shaped in such a way as to define channels (207) for conveying air from the side wall (205) of the casing towards the holes (106) in the bottom part (102) of the hub (101).

2. The electric ventilator according to claim 1, wherein the front wall (204) has a radiused surface (208) shaped to define an axial outlet for the channels (207) substantially at the holes (106).

3. The electric ventilator according to claim 1 or 2, wherein the second passage or mouth (112) is annular.

4. The electric ventilator according to any one of the preceding claims, wherein the disc-shaped element (109) has a maximum diameter (D) that is greater than the maximum diameter (d) of the side wall (103).

5. The electric ventilator according to any one of the preceding claims, wherein the disc-shaped element (109) comprises a curved peripheral surface (113) with concavity facing towards the side wall (103) and the first blades (108).

6. The electric ventilator according to any one of the preceding claims, wherein the holes (106) are made in the intermediate portion (102c).

7. The electric ventilator according to any one of the preceding claims, wherein the gap (110) has an axial width between 1 mm and 20 mm, preferably between 2 and 6 mm.

8. The electric ventilator according to any one of the preceding claims, wherein the disc-shaped element (109) is integral with the central portion (102a).

9. The electric ventilator according to claim 8, wherein the central portion (102a) is spaced outwardly away from the outer portion (102b) of the cup-shaped structure along the axis of rotation (R) of the impeller, the intermediate portion (102c) being preferably conical.

10. The electric ventilator according to any one of claims 1 to 7, wherein the disc-shaped element (109) is integral with the outer portion (102b).

11. The electric ventilator according to any one of the preceding claims, wherein the impeller (100) comprises a plurality of second blades (115, 115a, 115b), disposed in the gap (110), the bottom part (102) of the hub, the second blades (115, 115a, 115b) and the disc-shaped element (109) defining a centrifugal impeller (116) having an axial inlet, defined by the first passage (111), and a radial outlet, defined by the passage (112).

12. The electric ventilator according to claim 11, wherein the second blades extend between the central portion (102a) and the outer portion (102b) of the bottom part (102) of the hub (101).

13. The electric ventilator according to claim 11 or 12, wherein the second blades (115, 115a, 115b) are made as a single part with the hub (101).

14. The electric ventilator according to claim 11 or 12, wherein the second blades (115, 115a, 115b) are made as a single part with the disc-shaped element (109).

15. The electric ventilator according to any one of claims 11 to 14, wherein the disc-shaped element (109) is joined to the hub (101) by the second blades (115, 115a, 115b).

16. The electric ventilator according to any one of the preceding claims, wherein the axial impeller (100) comprises a plurality of vanes (118) disposed inside the cup-shaped structure and extending from the bottom part (102) of the hub (101), the vanes (118) extending predominantly axially and in a direction that is inclined to a tangential direction at a leading angle between 5° and 45°, preferably between 10° and 20°.

17. The electric ventilator according to claim 16, wherein the vanes (118) have a wing profile with a leading angle between 5° and 45°, preferably between 10° and 20°.

Drawing