Screw compressor

A screw compressor that at least comprises the following elements:

• a compression chamber, comprising an inlet and an outlet, that is formed by a compression housing in which a pair of meshed helical compressor rotors in the form of screws are rotatably mounted;
• rotor shafts of said meshed helical compressor rotors extend parallel to one another along first and second rotational axes, respectively;
• a non-return valve provided at the inlet of the compression chamber;
• a drive motor that is provided with a motor chamber formed by a motor housing, in which a motor shaft is rotatably mounted that drives at least one of the aforementioned pair of meshed helical compressor rotors,
• wherein the compression housing and the motor housing are connected directly to one another to form a compressor housing, whereby the motor chamber and the compression chamber are not sealed off from one another and whereby the screw compressor is a vertical screw compressor in which the rotor shafts of the compressor rotors as well as the motor shaft extend at an angle transverse to the horizontal plane during normal operation of the screw compressor,
• a pressure vessel, arranged downstream and separate from the compressor housing, comprising an outlet valve,
• wherein, when the screw compressor is stopped, the pressure vessel, the compression chamber, and the motor chamber are configured to be able to be in fluid communication and remain under a substantially constant compression pressure until the screw compressor is restarted,
• wherein the drive motor is an electric motor with a motor rotor and a motor stator,
• wherein the electric motor is equipped with permanent magnets to generate a magnetic field, and
• wherein the position of the motor rotor is determined by measuring the difference between an inductance of the electric motor along a direct motor axis and an inductance of the electric motor along an axis perpendicular to said direct motor axis, wherein the measuring takes place at a position outside of the compressor housing.

A screw compressor that at least comprises the following elements:

• a compression chamber, comprising an inlet and an outlet, that is formed by a compression housing in which a pair of meshed helical compressor rotors in the form of screws are rotatably mounted;
• rotor shafts of said meshed helical compressor rotors extend parallel to one another along first and second rotational axes, respectively;
• a non-return valve provided at the inlet of the compression chamber;
• a drive motor that is provided with a motor chamber formed by a motor housing, in which a motor shaft is rotatably mounted that drives at least one of the aforementioned pair of meshed helical compressor rotors, wherein the compression housing and the motor housing are connected directly to one another to form a compressor housing, whereby the motor chamber and the compression chamber are not sealed off from one another and whereby the screw compressor is a vertical screw compressor in which the rotor shafts of the compressor rotors as well as the motor shaft extend at an angle transverse to the horizontal plane during normal operation of the screw compressor,
• a pressure vessel, arranged downstream and separate from the compressor housing, comprising an outlet valve,
• wherein, when the screw compressor is stopped, the pressure vessel, the compression chamber, and the motor chamber are configured to be able to be in fluid communication and remain under a substantially constant compression pressure until the screw compressor is restarted, and
• wherein the motor shaft is supported axially and radially in the compressor housing by ball bearings, which are equipped with tensioning means for exerting an axial pre-load on said ball bearings, and this pre-load is oriented along an axial direction of the motor shaft.