A compressor may include first and second scrolls, an axial biasing chamber, and a modulation control valve. The second scroll includes an outer port and an inner port. The outer and inner ports may be open to respective intermediate-pressure compression pockets. The modulation control valve may be in fluid communication with the inner port, the outer port, and the axial biasing chamber. Movement of the modulation control valve into a first position switches the compressor into a reduced-capacity mode and allows fluid communication between the inner port and the axial biasing chamber while preventing fluid communication between the outer port and the axial biasing chamber. Movement of the modulation control valve into a second position switches the compressor into a full-capacity mode and allows fluid communication between the outer port and the axial biasing chamber while preventing fluid communication between the inner port and the axial biasing chamber.

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.

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 turbocharger generating a vacuum negative pressure may include a compressor which receives, through a turbocharger shaft, a rotational force of a turbine which rotates based on exhaust gas from an engine and turbo-charges an intake which is supplied to the engine, and a motorless vacuum pump coupled to the turbine through a center housing which is coupled to the compressor and is configured to be rotated by the turbocharger shaft, thus generating a vacuum negative pressure.

A lubrication system is provided for supplying lubricant to an air compressor. The air compressor is driven by a drive system. The lubrication system includes a reservoir configured to support lubricant and configured to receive pressurized air from the air compressor, the separator reservoir configured to separate lubricant from the air received from the air compressor; and a motor operably coupled to the drive system and configured to receive pressurized lubricant. The motor is configured to transmit power to the drive system in at least one operating condition.

A lubrication system is provided for supplying lubricant to an air compressor. The air compressor is driven by a drive system. The lubrication system includes a reservoir configured to support lubricant and configured to receive pressurized air from the air compressor, the separator reservoir configured to separate lubricant from the air received from the air compressor; and a motor operably coupled to the drive system and configured to receive pressurized lubricant. The motor is configured to transmit power to the drive system in at least one operating condition.

A method for regulating the temperature at an outlet channel of a compressor or a vacuum element, comprising providing a pressure regulating valve on a influence channel, said influence channel being in direct fluid communication with the compressor or vacuum element, said valve regulating the pressure within the compressor or vacuum element by adjusting the volume of fluid flowing between a process channel and the compressor or vacuum element relative to the difference between the pressure value within said compressor or vacuum element and a set pressure value, and comprises starting the compressor or vacuum element and starting a pre-purge cycle by connecting the inlet channel to a supply of a purge gas for a preselected time interval; connecting the influence channel to a process channel; and disconnecting the inlet channel from the process channel, for maintaining a set temperature within the vacuum element for a selected time interval.

A method for regulating the temperature at an outlet channel of a compressor or a vacuum element, comprising providing a pressure regulating valve on a influence channel, said influence channel being in direct fluid communication with the compressor or vacuum element, said valve regulating the pressure within the compressor or vacuum element by adjusting the volume of fluid flowing between a process channel and the compressor or vacuum element relative to the difference between the pressure value within said compressor or vacuum element and a set pressure value, and comprises starting the compressor or vacuum element and starting a pre-purge cycle by connecting the inlet channel to a supply of a purge gas for a preselected time interval; connecting the influence channel to a process channel; and disconnecting the inlet channel from the process channel, for maintaining a set temperature within the vacuum element for a selected time interval.

A scroll compressor according to the present invention includes a casing, an orbiting member provided within the casing and performing an orbiting motion, a non-orbiting member forming a compression chamber together with the orbiting member, the compression chamber having a suction chamber, an intermediate pressure chamber and a discharge chamber, a communication passage configured to bypass a refrigerant of the compression chamber into the casing, an opening/closing valve assembly configured to open and close the communication passage, and a switching valve assembly configured to operate the opening/closing valve assembly, the switching valve assembly being provided outside the casing and connected to the opening/closing valve assembly, whereby an installation of the bypass hole can result in prevention of over-compression and an installation of a control valve for varying a capacity outside the casing can result in reduction of costs for the control valve.

A method for controlling a compressor towards an unloaded state, in which the compressor includes a compressor element (2) with an inlet (5), in which in the unloaded state, a residual flow (QD) is suctioned via the inlet (5) towards and into the compressor element (2), and in which for a transition from a loaded state of the compressor to the unloaded state, the inlet (5) of the compressor element (2) is partially closed in successive discrete transitional steps.