The device comprises an electric motor having a planar airgap the rotor of which constitutes a flywheel capable of being coupled frictionally with a plate rigid with the shaft of the heat engine to be started. For this purpose, the motor is axially movably mounted in a case between an uncoupled position to which it is biased by a spring and a position in which it is coupled with the plate. The motor is brought to the latter position by the excitation of a clutch coil carried by the rotor and exerting a force of attraction between the rotor and the plate in opposition to the action of the spring. Owing to its small axial overall size, this device requires only a low electric power and may be adapted to mopeds.
A power source for a starter motor comprising a frame, a hand crank rotatably connected to the frame, a flywheel generator connected to the hand crank, and power transmission electrically connected to the flywheel generator so as to transmit energy to a starter motor. The flywheel generator comprises a flywheel connected to the hand crank, a permanent magnet fixedly attached to the flywheel, and a stator winding mounted to the frame. The stator winding is electrically connected to the power transmitter. The power transmitter includes a rectifier bridge electrically connected to the flywheel generator and connector leads for connecting the rectifier bridge to terminals associated with a starter motor. A gear train is arranged within the frame so as to transmit a greater rate of rotation to the flywheel.
A propulsion system for use in automotive vehicles wherein the flywheel is connectable with the crankshaft of the internal combustion engine by a first clutch and with the input shaft of the change-speed transmission by a second clutch. When the engine would be idling (such as during stoppage of the vehicle at an intersection) or running unnecessarily for another reason (such as during coasting of the vehicle), the two clutches are disengaged and the flywheel rotates by inertia to restart the engine, when necessary, in response to engagement of the first clutch. If the RPM of the flywheel reaches a preselected lower threshold value, a starter-generator unit automatically accelerates the flywheel so that its RPM rises above the threshold value and is thus sufficient to ensure that the engine is restarted on engagement of the first clutch. The starter-generator unit has a rotor which is mounted directly on the flywheel and a stator which surrounds the rotor with minimal clearance and is connected directly to the housing of the engine. The generator of the starter-generator unit is a heteropolar Schmidt-Lorenz generator.
A flywheel system having permanent magnets 20 disposed on a flywheel 10 rotating about a shaft 12 is provided with a stator 28 having an outer diameter which is oriented concentrically and shaped conically within a similarly shaped inner diameter of the flywheel 10 (and the magnets 20) and the stator 28 is slidably and rotatably mounted to a shaft 30 thereby allowing a gap g.sub.1 between the stator 28 and the rotor/flywheel 10 to be adjustable. When energy is being provided to (spin-up) or extracted from (spin-down) the flywheel 10, the stator is automatically forced to the left (FIG. 1) due to torque on the stator 28, thereby causing the gap g.sub.1 to be small to provide strong electromagnetic interaction between the stator 28 and the flywheel 10. Conversely, when the flywheel 10 is freewheeling, the stator 28 is forced to the right by a spring 40 causing the gap g.sub.1 to increase to a distance large enough to minimize electro-magnetic drag on the flywheel 10.
The maximum kinetic energy per unit weight which can be stored in a rotating article, such as a flywheel, is a function of the tensile strength and the density of the material and is dramatically increased by subjecting it to an externally applied, inwardly directed radial pressure. The additional pressure is imposed by external means and is independent of the rotational motion of the article per se. Suitable pressurizing methods include magnetic containment, super-atmospheric gas containment, electrostatic containment and the like. As a result of the external pressure, the maximum stored energy per unit of mass (E.sub.max /m) of a rim flywheel can be greatly increased in accordance with the relationship: ##EQU1## where .delta. is the uniform tensile strength of the flywheel material, .rho. is its density, R is the radius of the flywheel, and P is the external pressure. As a result, the maximum storage energy per unit mass of a flywheel need no longer be limited solely by its tensile strength and density in accordance with the classical first term of this equation. This invention enables the practical use of flywheels for storing energy during off-peak power plant operation with subsequent extraction during peak demand periods, for powering vehicles and for numerous other applications. The phenomenon underlying this invention can also be used to improve the overall performance of rotating articles in general, e.g., by providing a method for correcting dynamic imbalances.
