1. Field of the Invention
The present invention relates to a ventilation device for feeding cooling air toward a rotating electric machine body from one or both sides of the rotating electric machine by revolution of a fan to cool the same.
2. Description of the Prior Art
FIGS. 1 and 2 illustrate the conventional device of this kind. In the figures, the reference numeral (1) designates a stator core, (2) designates a rotor core surrounding the stator core, (3) designates a stationary coil at one end of the stator core, (4) designates an end ring at one end of the rotor core, (5) designates a fan, (6) designates a rotary shaft, (7) designates a spider mounted on said shaft and to which the rotor core and fan are mounted, (8) designates a first side plate (referred to as a ventilation guide) which is placed near the fan (5), abuts one side of the stator core, and has an opening at the center, (9) designates a housing and (10) designates a second side plate of the housing placed facing the ventilation guide (8) with a gap in the axial direction. The reference numeral (21) designates an intake port in the housing for cooling air which is formed between the ventilation guide (8) and the second side plate (10), (22) designates a discharge port in the housing and separated from the intake port by the ventilation guide, (11) designates a shielding plate of the housing placed to cover between the ventilation guide (8) and the second side plate (10) except for the intake port, and (20) designates a sucking chamber formed by the ventilation guide (8), the second side plate (10) and the shielding plate (11).
In the conventional rotating electric machine, when the fan (5) and the rotor core (2) are rotated with the rotary shaft (6), cooling air is sucked through the intake port (21) into the sucking chamber (20). One part of the cooling air is passed through the opening of the ventilation guide (8) and the fan (5) to cool the stationary coil (3) and the other part is directed in the axial direction from the spaces of the spider (7) to cool the rotor core (2) and the stator core (1) and is discharged through the discharge port (22) of the frame (9).
In the conventional rotating machine having the structure described above, the cooling air is sucked through the intake port (21) into the sucking chamber (20) as shown by the arrow marks (a), (b) in FIG. 2 and flows while whirling as shown by the arrow marks (c), (d) by centrifugal effect caused by revolution of the fan (5). Near the portion designated by the letter (e), a whirling air stream (d) crosses sucked air stream (b), thus the sucked air stream (b) is deflected in the direction as shown by the broken line. A part of the whirling air stream (d) is also deflected in the direction shown by the arrow mark (f) to be discharged through the intake port (21).
It is necessary that the direction of the cooling air flowing to the blades of the fan (5) and the rotor core is changed by 90.degree. with reference to the sucking direction; however it is extremely difficult to change the direction of flow because of the force of inertia of the whirling streams (c), (d), so that imaginary resistance of air flow increases. It is therefore, observed to be difficult to effectively cool the cores and the coils.