Abstract: The invention relates to a piston accumulator (1) and a method for determining a position of a piston (5) that can be moved inside a housing (3) of the piston accumulator (1). One or more inductive sensors (15) are arranged on an exterior surface (21) of the housing (3) and configured to detect a movement of the piston (5) inside the housing (3) caused by electromagnetic induction. In this way, a determination of the current position of the piston (5), which is technically simple to realise and contact-free, can be implemented and used, for example, to monitor a charge state of the piston pressure accumulator (1).

Abstract: The invention relates to a method for determining a position of a piston (5) in a piston pressure accumulator (1) and a ON correspondingly designed piston pressure accumulator (1). A housing (3) accommodates a displaceable piston (5). An electrode arrangement (15) having a plurality of 4-point measurement electrode pairs (17) is provided on the electrically conductive housing (3) and is designed to determine a position of the piston (5) inside the housing (3) by measuring a distribution of an electrical resistance or potential between inner electrodes (21) when a current is applied to outer electrodes (19), depending on a position along the housing (3). The position of the piston determined from the measurement of the potential distribution can be used to determine or check a charge state of the piston pressure accumulator (1).

Abstract: A method for ascertaining learned values for controlling an internal combustion engine, a second drive unit, e.g., an electric motor, drags the internal combustion engine in a specific operating state, and the learned values are ascertained in this operating state.

Abstract: The invention relates to a hybrid drive system comprising an internal combustion engine (11) which is operated using fuel (21) from a fuel tank (20), and comprising a hydraulic machine (12) which interacts with a hydraulic energy store (38). In order to provide a hybrid drive system which requires less installation space than conventional hybrid drive systems, the hydraulic machine (12) is operated with the same fuel (21) with which the internal combustion engine (11) is also operated.

Abstract: A method for ascertaining learned values for controlling an internal combustion engine, a second drive unit, e.g., an electric motor, drags the internal combustion engine in a specific operating state, and the learned values are ascertained in this operating state.