Abstract: A transmission for an energy storage and recovery system comprises a variable slip transmission and a clutch arranged to transmit drive while slipping. The level of torque transmitted through the slipping clutch is dependent on the clutch force but is independent of the clutch slip speed. Preferably the clutch is provided by a plurality of clutches connected in parallel in a range extender. When drive is transferred between clutches in parallel, the clutch forces of both clutches are controlled to maintain the total torque transmitted by the clutches. This reduces torque fluctuations at the energy source/sink during clutch transfer. Where there are two slipping clutches in series, one clutch is controlled to provide the required torque and the other clutch is controlled in response to a clutch slip speed. This helps to control the speed of rotation of the mass between the clutches.

Abstract: The invention relates to an energy storage and recovery system (ERS) coupleable to a prime mover and to an energy storage flywheel. The ERS has a hydrostatic arrangement with a first pumping element and a second pumping element. The pumping elements have a respective fluid displacement and a fluid coupling arrangement for the transfer of fluid power between the first and second pumping elements. The ERS also includes a differential device comprising at least three inputs, wherein a first driveshaft of the first pumping element is coupled to a prime mover in use, a first input of the a differential device is coupled to said prime mover in use, a second input of the differential device is coupled to a second driveshaft of the second pumping element, and the third input of the differential device is coupled to a flywheel in use.

Abstract: An energy storage and transmission system (ESRS) (69) comprises a transmission (9, 11) and an energy storage device such as a flywheel (1). While energy is being transferred between the energy storage device (1) and an energy source/sink (7), the transmission ratio of the transmission (9, 11) will usually be changing constantly. In order to manage the torque applied by the energy transfer device (1) or the power transferred, a controller (100) responds to discrepancy between the torque or power supplied and the torque or power demanded.

Abstract: The invention provides a flywheel system comprising a flywheel mounted for rotation within a chamber, a vacuum pump system and a valve for selectively closing a passage, wherein the chamber is coupled to an inlet of the vacuum pump system via the passage. The invention also provides a method of controlling the starting and stopping of the flywheel system.

Abstract: A transmission for an energy storage and recovery system is disclosed. A variable slip transmission and a clutch arranged to transmit drive while slipping. The level of torque transmitted through the slipping clutch is dependent on the clutch force but is independent of the clutch slip speed. Preferably the clutch is provided by a plurality of clutches connected in parallel in a range extender. When drive is transferred between clutches in parallel, the clutch forces of both clutches are controlled to maintain the total torque transmitted by the clutches. This reduces torque fluctuations at the energy source/sink during clutch transfer. Where there are two slipping clutches in series, one clutch is controlled to provide the required torque and the other clutch is controlled in response to a clutch slip speed. This helps to control the speed of rotation of the mass between the clutches.

Abstract: The present invention relates to a flywheel apparatus for energy storage and recovery including a housing within which there is a chamber in which a flywheel on a shaft rotates. The chamber is evacuated to at or near vacuum pressure, so that air resistance-related energy losses of the flywheel as it rotates are reduced. Maintaining near-vacuum pressure within the chamber requires an effective seal between the housing and the shaft. The effective seal must be maintained despite any relative movement (in particular translational movement) of the flywheel and the housing. To this end, the shaft is mounted via a bearing arrangement on a carrier on which is also mounted a sealing arrangement. The carrier is mounted on the housing such that the carrier, the bearing arrangement and the sealing arrangement move substantially together relative to the housing.