A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

An electric pump provided with a pump unit configured to discharge working oil by being rotationally driven by an electric motor includes: a drive shaft configured to transmit rotational driving force from the electric motor to a rotor of the pump unit; a rotation-detection shaft provided coaxially with the drive shaft, the rotation-detection shaft being configured to be rotated together with the rotor; and a rotation detector unit configured to detect rotation of the rotation-detection shaft. The rotation-detection shaft has: an engagement portion configured to engage with the rotor; and a detection-target portion facing the rotation detector unit, and an outer diameter of the detection-target portion is set so as to be larger than an outer diameter of the engagement portion.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.

Method for delivering a gas/liquid mixture fluid via a screw spindle pump that has a housing in which a drive spindle and a running spindle are accommodated. The spindles delimit together with the housing multiple pump chambers. A respective one of the pump chambers that is initially open toward the respective fluid inlet is closed off. The resulting closed-off pump chamber is moved axially toward the fluid outlet and, there, upon attainment of an opening rotation angle, is opened toward the fluid outlet. The drive spindle is driven so that the pressure in the respective pump chamber prior to and/or upon attainment of the opening rotation angle is increased in relation to the suction pressure of the screw spindle pump by at most 20% or by at most 10% of a difference in pressure between the suction pressure and the pressure in the region of the fluid outlet.

Techniques are provided for protecting a rotary positive displacement pump, e.g., using a signal processor that receives signaling containing information about power, torque, speed, viscosity and specific gravity related to the operation of a pump; and determines whether to enter an enhanced pump protection mode for the rotary positive displacement pump based at least partly on a relationship between an actual corrected tune ratio and a tuned ratio set point (Tune Ratio SP). The signal processor may determine if the actual corrected tune ratio is less than or equal to the actual corrected tune ratio set point (Tune Ratio SP), and if so, then to enter the enhanced pump protection mode, else continues to use a basic pump protection mode, and also determines the actual corrected tune ratio based upon a ratio of an actual corrected power (PAcorr) divided by a tuned corrected power (PTcorr) at a specific operating speed.

The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.

A vacuum pumping system includes a plurality of positive displacement vacuum pumps, and more particularly a plurality of positive displacement vacuum pumps working in parallel. The vacuum pumping system includes a management unit that carries out a synchronized control of all the positive displacement vacuum pumps of the vacuum pumping system and thus allows to check possible risk of contamination of the vacuum pumping system and carry out, if needed, the necessary corrective actions without requiring any modification to the construction of the vacuum pumping system.

Systems, methods, and computer-readable mediums are provided for improving the efficiency of a filter-type oil separator in a cooling system including a compressor that pumps a mixture of lubricating oil and refrigerant through the filter-type oil separator. The filter type oil separator is configured to receive a first portion of the mixture from the compressor, and a bypass line is configured to bypass a second portion of the mixture around the filter-type oil separator. The bypass line ensures a sufficient amount of oil is present in the compressor.

In order to improve a machine for depressurizing or compressing substantially gaseous media, comprising a machine casing and at least one screw rotor, which is arranged in a screw rotor bore in the machine casing, extends between a low-pressure side and a high-pressure side of the screw rotor bore, cooperates with the substantially gaseous medium and is mounted on both sides in the machine casing by means of a respective bearing set, and a motor/generator unit that is coupled or couplable to the at least one screw rotor, it is proposed that the at least one screw rotor should be provided with at least one axial support bearing that axially supports the at least one screw rotor such that a high-pressure end face of the at least one screw rotor is guided, without making contact, to an end wall, which faces this end face, of the machine casing that receives the at least one screw rotor.