Patent GB-1515009-A (GB)
Title: Flywheel accumulator for storing and releasing braking energy
IPC: B60T1/10
Filed: 1975-10-23
Abstract: 1515009 Momentum power-storing apparatus MASCHINENFABRIK AUGSBURG-NURNBERG AG 23 Oct 1975 [26 Oct 1974] 43608/75 Heading F2X [Also in Division B7] A flywheel accumulator for storing and releasing braking energy and for braking or driving a rotating shaft of a vehicle, e.g. a town bus, comprises a differential gear 2 for connection to the shaft, a flywheel 5, a first device 3 operable selectively as a generator or motor and connected for rotation with the flywheel 5 and one output of the gear 2 and a second device 4 operable as a generator or motor and connected for rotation with the other output of the gear 2, the two devices 3, 4 being connected for the transfer of energy therebetween via a buffer reservoir 6. The devices 3, 4 are either hydraulic machines operable as motors or pumps, or pneumatic machines operable as motors or compressors, and they are operable in four-quadrant operation, i.e. under + and -  speed as generators or motors. A second differential gear 1 connected via a transmission 8 to the differential gear 2 is, in the usual manner, mounted between the driving wheels of the vehicle. If the devices 3, 4 are hydraulic, each is provided with a collector 10 and the two collectors may be connected together. When braking occurs, the speed of device 3 increases in accordance with the geometry of the differential gear 2 and with it also the speed of the flywheel 5, while the device 4 functioning as a generator converts mechanical energy into hydraulic or pneumatic energy and supplies it to the flywheel 5 via the buffer reservoir 6 and device 3. Device 4 initially charges the reservoir 6 to a pressure determined by a control system 7 which, as soon as this pressure is reached, actuates device 3 selected to operate as a motor. When the vehicle is decelerating, the speed of device 4 falls to zero and by means of the pressure in the reservoir 6, device 3 is also regulated down to zero power by the control system 7. When device 4 passes zero, the control system 7 produces a signal to actuate device 3 selected to operate as a generator. In the - speed range device 4 operates as a motor. Device 3 operates at a + speed only. It is changed over by the control system 7 to operate as a motor when the pressure in the reservoir 6 exceeds a specified maximum. Should, however, this pressure fall below a specified minimum, device 3 will operate conversely as a generator. Between minimum and maximum pressure, device 3 is changed over to idle load. If the vehicle needs energy to accelerate, then flywheel 5 transmits mechanical energy to the differential gear 2 while at the same time driving 4 to produce hydraulic or pneumatic energy which is stored in the reservoir 6. Device 4 transmits a positive torque to the differential gear 2 which in turn transmits energy derived directly from the flywheel 5 as well as indirectly, via devices 3, 4, to the differential gear 1. As soon as device 4 passes zero speed during acceleration, the control system 7 changes over device 3 to operate as a generator. At + speed device 4 operates as a motor. If a pneumatic system including a pressure reservoir 6 is used, the buffer reservoir 6 may include a heat exchanger 11, connected to the prime mover and comprising, for example, a pipe through which the exhaust gases are passed. The normally wasted exhaust gases are thereby used to raise the pressure level in the reservoir 6. The control system 7 may be arranged to by-pass or cut off the heat exchanger when the reservoir 6 is full and the flywheel 5 is rotating at nominal speed with the vehicle stationary.