Generator with series stators, and series rotors separated by annular collars with cooling vents

1. A generator comprising: a series of spaced annular stators sandwiched between a series of rotors, the rotors each being separated by annular collars, the annular collars defining a central cavity; at least one cooling gas source for supplying gas to the central cavity; vents through the annular collars for providing a means of egress for the cooling gas from the central cavity radially outwards over the rotors and the annular stators; and a central shaft on which the rotors and annular collars are carried, wherein: the cooling gas source comprises one or more fans caused to rotate by an ancillary electric motor, and the one or more fans are mounted on the central shaft, wherein the diameter and/or number of vents through at least one of the annular collars is gradually increased the further away the at least one annular collar is from the cooling gas source.

2. The generator of claim 1 , wherein the number and/or aperture size of the vents is so selected as to ensure a substantially even dispersal of cooling gas over any given pair of rotors and the stator sandwiched between them regardless of the spacial separation of the said pair of rotors and their respective sandwiched stator from the at least one cooling gas source.

3. The generator according to claim 1 , wherein the vents are angled relative to a true radius of the collars to assist dispersal of the cooling gas in a spiral direction opposite to the direction of rotation of the collars, in use.

4. The generator according to claim 1 , wherein an outlet of each vent in a radially outer surface of the respective annular collar is axially aligned with one or both axial ends of a respective annular stator and/or an axial end of a respective rotor.

5. The generator of claim 1 , wherein the cooling gas source comprises two fans, positioned at each end of the central cavity, and configured to feed equal amounts of gas into the central cavity.

6. The generator of claim 1 , further comprising one or more radial support members affixed to the rotors and extending inwardly towards the central shaft.

7. The generator of claim 6 , wherein the radial support members extend inwardly from the rotors towards housings carrying one or more central bearings mounted upon the central shaft, enabling the rotor assembly to rotate around the central shaft.

8. The generator of claim 6 , wherein the radial support members are permanently affixed to the central shaft, such that the rotors and shaft rotate together.

9. The generator according to claim 1 , wherein the generator is mounted substantially hermetically within a housing, there being one or more orifices in the housing specifically to permit the intake of cooling gas, and one or more further orifices in the housing for allowing cooling gas to escape.

10. The generator of claim 9 , wherein the at least one cooling gas source comprises means for facilitating the forced extraction of the cooling gas through the one or more further orifices.

11. The generator of claim 10 , wherein the means for facilitating the forced extraction of the cooling gas comprises one or more fans for sucking gas out of the housing.