There is provided an apparatus comprising a synthetically commutated machine (100) with one or more services, a prime mover (150) coupled to the machine, a hydraulic circuit extending between the one or more services and the plurality of hydraulic loads to thereby fluidically connect the one or more services to the plurality of hydraulic loads such that groups of one or more services are fluidically connected to respective groups of one or more hydraulic loads, the apparatus configured such that the flow of hydraulic fluid to or from a group of one or more services of the machine is controlled responsive to measuring a flow rate and/or pressure requirement of the group of one or more hydraulic loads which are fluidically connected to the group of one or more services, or receiving a demand signal indicative of a demanded pressure and/or flow rate based on a pressure and/or flow demand of the group of one or more hydraulic loads which are fluidically connected to the group of one or more services. The apparatus may for example be an excavator.

Hydraulic apparatus comprising synthetically commutated machine, and operating method

The present invention relates to a hydraulic circuit for a working machine, the hydraulic circuit comprising a hydraulic actuator and an accumulator for accumulating hydraulic energy discharged from the hydraulic actuator, and addresses the problem of configuring the hydraulic circuit so that high-temperature hydraulic oil does not flow into the accumulator. A means for solving the problem is to configure the hydraulic circuit in such a manner that piping (12) for cooling which has a volume corresponding to the pressure accumulation volume of the accumulator (10) is provided in an accumulator outlet/inlet oil passage (9) serving as the inlet oil passage for hydraulic oil flowing into the accumulator (10), and in such a manner that hydraulic oil cooled by the piping (12) for cooling is accumulated in the accumulator (10).

Hydraulic circuit for working machine, comprising accumulator

A motor drive and method of controlling a motor are provided. The motor drive includes a controller generating a motor reference voltage; a DC bus providing a DC voltage having a ripple; an inverter including power switches operable to convert the DC voltage into an AC motor voltage by modulating the power switches during a plurality of switching cycles, the AC motor voltage based on the motor reference voltage; a capacitor circuit coupled to the DC bus and having a maximum capacitance that is less than 10 microfarads per ampere of a rated current; and voltage prediction logic structured to: detect a voltage value corresponding of the ripple during each of the plurality of switching cycles; and modify the motor reference voltage during each of the plurality of switching cycles using the voltage value.

Motor drive system and method

The present invention relates to a method for monitoring a speed-controlled electric motor pump of a hydraulic circuit of an aircraft, wherein the electric motor pump comprises at least one electric motor having variable speed for driving the hydraulic pump and a hydraulic jacket cooling for cooling the electric motor pump is provided, through which the hydraulic medium conveyed by the pump flows, wherein the volume flow through the jacket cooling is detected for different motor speeds of the electric motor pump, in order to determine the volumetric efficiency of the pump.

Method for monitoring a speed-controlled electric motor pump of a hydraulic circuit in an aircraft and a hydraulic system for carrying out the method

The invention relates to a hydraulic system with at least one hydrostatic displacement unit (2, 4), a filter unit (6) for filtering the hydraulic oil flowing through the respective displacement unit (2, 4), and a discharge device (10) that filters the leakage oil accumulating at each displacement unit (2, 4) during operation and supplies it to a tank (8). The system is characterized in that the discharge device (10) has a pump device (26) by means of which the leakage oil can be brought to a pressure suitable for feeding to the filter device (6).

Hydraulic system with at least one hydrostatic displacement unit

Example fluid circuits (e.g., within aircrafts) include first (12) and second (32) pump assemblies. The first pump assembly has an electric motor (18) and a first fluid pump (16). The first fluid pump is coupled to the electric motor and has a case drain port (30) that is in fluid communication with a case drain region of the first fluid pump. The second pump assembly is powered by hydraulic pressure from the first fluid outlet (22) of the first fluid pump and functions to augment flow through the case drain region of the first fluid pump.

Kelly Dale Valtr

Papers

Case flow augmenting arrangement for cooling variable speed electric motor-pumps