This invention relates to a fan and a ventilation unit comprising a fan and a corresponding shroud.
The ventilation groups referred to in this specification are those generally formed by a fan and a support shroud of the fan, for cooling radiators in automotive applications.
The fan is usually constituted by an electric motor, preferably of the closed type, for actuating a corresponding fan, of the axial type in the present case.
The electric motor has a casing, a cap for closing the casing and an outlet shaft which is solidly constrained to the fan by means of a cup-shaped hub which at least partly houses the motor itself and from which a plurality of blades project.
The shroud is provided for supporting the motor by means of a corresponding support ring and for at least partly housing the fan in such a way as to optimise heat removal from the radiator.
The shrouds, in particular, generally comprise an external tubular member, having a substantially cylindrical end wall, to which the support ring is connected by means of a plurality of arms or spokes which project from the cylindrical wall internally of the tubular element.
The support ring is coaxial with the cylindrical wall and the motor is mounted coaxially with the support ring.
The prior art solutions have some drawbacks.
The positioning and fixing of the fan in the shroud do not enable effective removal and evacuation of the heat generated by the electric motor in operation, i.e. an adequate cooling of the cap and the casing is not enabled.
In general, the ring of the shroud for supporting the motor surrounds the motor itself and does not allow the circulation of an air flow suitable carrying of the heat generated in use.
The hub of the fan is in general very closed on the motor and also prevents a circulation of air which cools down the casing and the cap of the electric motor by convection.
One example of known solution is disclosed in document
Failure to cool the motor limits the operating temperature and therefore the performance.
If, on the other hand, particular levels of performance are required, the duration over time of the motor is limited, should it not be properly cooled. In this context, the main aim of this invention is to obviate the above-mentioned drawbacks.
The aim of the present invention is to provide a fan which contributes to generating a flow of air for cooling the electric motor, in particular both the cap and the casing.
Another aim of the invention is to disclose a ventilation group which allows a better passage of air around the cap and the casing of the electric motor than the prior art solutions.
The stated technical purpose and aims of the invention are substantially achieved by a fan according to claim 1 and a ventilation group according to claim 9.
Further characteristics and advantages of the invention will become more apparent from the non-limiting description that follows of a preferred but non-limiting embodiment of a ventilation group as illustrated in the accompanying drawings, in which:
With particular reference to
The ventilation group 1 is preferably destined for automotive applications in the sector of radiator cooling.
The ventilation group 1 comprises a fan 2 having an axis R of rotation and a support shroud 3 of the fan 2.
The fan 2 comprises an electric motor 4 and a fan 5 having axial flow, or simply an axial fan, actuated by the motor 2, rotatable about the axis R of rotation.
As illustrated in particular in
In particular, the shaft 8 comprises an end portion 9 protruding from the casing 6 on the opposite side with respect to the cap 7 to which the fan 5 is connected, for example by interference fitting.
The shroud 3 comprises a ring 10 for supporting the motor 4, to which the motor 4 is fixed in the substantially known way, for example, by means of screws in suitable protrusions extending from the ring 10.
The motor 4 is inserted internally of the fixed ring 10 and is supported thereby.
The ring 10 has a external annular wall 11 from which project, on the side opposite the motor, a plurality of arms or spokes 12 of substantially known type.
The wall annular 11 advantageously projects axially up to the cap 7 on the opposite side to the fan 5.
The wall 11 preferably, has radial dimensions equal to the radial dimensions of the hub 14.
The shroud 3 comprises a tubular element 13 external of the ring 10 and to which the arms 12 are connected.
In general the ventilation group 1 is installed in a generic application, which is not illustrated, by means of the element tubular 13 which in turn, by means of the arms 12 and the ring 10, supports the fan 2.
Observing the fan 5 in more detail, it should be noted that it comprises a cup-shaped hub 14 and a plurality of blades 15 extending from the hub 14 and preferably made in a single body with the hub by moulding using a plastic material.
As illustrated in
The hub 14 comprises an end wall 16 by means of which the fan 5 is connected to the shaft 8.
The hub 14 comprises a lateral wall 17 extending from the end wall 16 and having a peripheral edge 18, substantially circular in shape, on the side opposite the end wall 16 along the axis R of rotation.
The end wall 16 and the lateral wall 17 define a cup-shaped structure for the hub 14.
The blades 15 extend preferably from the lateral wall 17 of the hub 14 towards the outside thereof, externally of the cup-shaped structure.
With reference in particular to
In the illustrated preferred embodiment, the fins 19 are angularly equispaced internally of the hub 14 and are for example seven in number.
Each fin 19 comprises a portion 20 projecting beyond the peripheral edge 18 of the lateral wall 17, externally of the cup-shaped structure, i.e. outside the hub 14.
Preferably, the end portions 20 protrude externally of the hub 14 along an axial direction, substantially parallel with the axis R of rotation of the fan 2.
In the illustrated preferred embodiment, each appendage 19 has a first portion 21 extending from lateral wall 17 internally of the hub 14, preferably radially.
The first portion 21 has main extension direction that is parallel to the axis R of rotation of the fan 5 and preferably extends along the entire axial dimension of the hub 14 towards the inside of the hub 14.
The end portions 20 are preferably defined by an at least partial extension of the first portion 21 beyond the edge 18.
In the preferred embodiment illustrated, each fin 19 comprises a second portion 22 extending from the end wall 16 towards the inside of the hub 14.
Each second portion 22 is connected and extends into a corresponding first portion 21.
Each second portion 22 preferably has a main extension direction that is substantially radial and extends towards the inside of the hub 14.
With reference in particular to
Each end portion 20 has an internal edge 23 facing internally of the hub 14, i.e., towards the electric motor 4, and an external edge 24 facing externally of the hub 14, i.e. towards the blades 15.
According to the invention, the external edge 24 is at a radial distance from the axis R of rotation that is less than a radial distance of a radially inner surface of the lateral wall 17 from the axis R of rotation.
In practice, each portion 20 is slimmed in a radial direction relative to the corresponding first portion 21 of the respective fin 19.
To facilitate outflow of the air moved by the fins 19 in use, the hub 14 has a plurality of through-holes 25 at a connecting zone 26 of the end wall 16 and the lateral wall 17.
The connecting zone 26 preferably has a curved extension and the holes 25 preferably have rounded edges.
The heat removed from the casing and the cap, in a flow having a prevalently axial component, advantageously flows out from the hub 14 through the holes 25.
With reference in particular to
The end portions 20 of the fins 19 are preferably at least partly inserted internally of the channel 27.
More precisely, the portions 20 are slimmed as described in the foregoing so as to be inserted internally of the channel 27.
The lateral wall 11 of the ring 10 preferably has a radial dimension substantially corresponding to the radial dimension of the hub 14 and in particular of the lateral wall 17 thereof. More precisely, a substantially cylindrical internal surface of the wall 11 has the same internal diameter as the lateral wall 17 of the hub 14.
In this way, a descending flow of tangential air is guided about the casing 6 and the cap 7 of the motor so as to carry heat away from both.
In particular, a component of the tangential flow for cooling the cap is determined by the portions 20 of the fins which extend outside the hub internally of the annular channel 27.
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