This disclosure relates to an axial magnetic bearing for a centrifugal refrigerant compressor, and a corresponding system and method. A centrifugal refrigerant compressor system according to an exemplary aspect of the present disclosure includes, among other things, an impeller connected to a shaft, and a magnetic bearing system supporting the shaft. The magnetic bearing system includes an axial magnetic bearing, which itself includes a first permanent magnet configured to generate a first bias flux, a second permanent magnet axially spaced-apart from the first permanent magnet and configured to generate a second bias flux, and an electromagnet. The electromagnet includes a coil arranged radially outward of the first and second permanent magnets, and the electromagnet is configured to selectively generate either a first control flux or a second control flux to apply a force to the shaft in a first axial direction or second axial direction opposite the first axial direction, respectively.

A vacuum pump for rotary driving a rotor by a motor to perform vacuum pumping, wherein a motor rotor of the motor includes a yoke fixed to a shaft of the rotor, and a permanent magnet held at the yoke, and the yoke includes a holding portion provided apart from the shaft and configured to hold the permanent magnet, and a pair of fitting portions provided respectively at both ends of the holding portion in an axial direction and bonded to the shaft by fitting, and a radial thickness dimension of each fitting portion is set less than that of the holding portion.

An arrangement includes a vacuum pump having a rotor, and a drive unit for driving the rotor and having at least one magnetic interference field-generating component and at least one compensation coil for compensating the magnetic interference field generated by the at least one component.

A vacuum pump comprises a cylindrical rotor; a cylindrical stator which discharges gas in cooperation with the rotor; a base housing at least a part of the stator and having a through hole formed at a position facing an outer periphery of the stator; a heating member passing through the through hole from an atmosphere side to a vacuum side to have thermal contact with an outer peripheral surface of the stator to heat the stator; and an axial seal member which vacuum-seals a gap between the through hole and the heating member.

A motor-compressor unit for sub-sea applications, including a pressure casing, and an electric motor housed in a motor compartment formed in the pressure casing and a compressor housed in a compressor compartment formed in the pressure casing. A shaft drivingly connects the electric motor and the compressor. At least one magnetic bearing rotatingly supports the shaft and a control system is provided for controlling the magnetic bearing. The control system is housed in a control system compartment structurally connected to and supported by the pressure casing.

A motor-compressor unit for sub-sea applications, including a pressure casing, and an electric motor housed in a motor compartment formed in the pressure casing and a compressor housed in a compressor compartment formed in the pressure casing. A shaft drivingly connects the electric motor and the compressor. At least one magnetic bearing rotatingly supports the shaft and a control system is provided for controlling the magnetic bearing. The control system is housed in a control system compartment structurally connected to and supported by the pressure casing.

A machine learning device learns a control condition for a magnetic bearing device that includes a magnetic bearing having a plurality of electromagnets that apply an electromagnetic force to a shaft. The machine learning device includes a learning unit, a state variable acquisition unit, an evaluation data acquisition unit, and an updating unit. The state variable acquisition unit acquires a state variable including at least one parameter correlating with a position of the shaft. The evaluation data acquisition unit acquires evaluation data including at least one parameter selected from a measured value of the position of the shaft, a target value of the position of the shaft, and a parameter correlating with a deviation from the target value. The updating unit updates a learning state of the learning unit by using the evaluation data. The learning unit learns the control condition in accordance with an output of the updating unit.

A vacuum pump includes; a rotor, a stator, a motor, a heating section heating the pump base portion, a base temperature detection section detecting a temperature of the pump base portion, a rotor temperature detection section detecting a temperature equivalent as a physical amount equivalent to a temperature of the rotor, and a heating control section to control heating of the pump base portion by the heating section such that a detection value of the rotor temperature detection section falls within a predetermined target value range. A monitoring device comprises: an estimation section configured to estimate, based on multiple temperatures detected over time by the base temperature detection section, maintenance timing at which the temperature of the pump base portion reaches equal to or lower than a predetermined temperature; and an output section configured to output maintenance information based on the estimated maintenance timing.

An exhaust pump includes: a cylindrical rotating member; an outer cylindrical fixed member; an inner cylindrical fixed member a helical inner thread groove exhaust passage provided between the cylindrical rotating member and the inner cylindrical fixed member; connecting opening portions that are opened in the cylindrical rotating member and that lead a part of gas existing in the vicinity of the outer periphery of the cylindrical rotating member towards the inner thread groove exhaust passage. A gap between an upstream end of the connecting opening portions and lowermost stage rotor blades provided at the outer periphery of the cylindrical rotating member which is located upstream of the connecting opening portions has a dimension equal to or greater than a dimension that enables insertion, into the gap, of a tool for opening the connecting opening portions.

An exhaust pump includes: a cylindrical rotating member; an outer cylindrical fixed member; an inner cylindrical fixed member a helical inner thread groove exhaust passage provided between the cylindrical rotating member and the inner cylindrical fixed member; connecting opening portions that are opened in the cylindrical rotating member and that lead a part of gas existing in the vicinity of the outer periphery of the cylindrical rotating member towards the inner thread groove exhaust passage. A gap between an upstream end of the connecting opening portions and lowermost stage rotor blades provided at the outer periphery of the cylindrical rotating member which is located upstream of the connecting opening portions has a dimension equal to or greater than a dimension that enables insertion, into the gap, of a tool for opening the connecting opening portions.