Abstract: The present invention provides a rotary machine abnormality detection device capable of determining abnormality with higher accuracy, a method thereof, and a rotary machine provided therewith. A rotary machine abnormality detection device AD of the present invention detects abnormality in a rotary machine M having at least first and second rotating bodies using a specific feature amount based on a frequency spectrum of measurement data of vibration. The device obtains, from the frequency spectrum, a fundamental wave component F1 of a fundamental wave lobe mesh frequency f1 and n-th harmonic wave components Fn of n-th harmonic wave lobe mesh frequencies fn up to XAB, and obtains the specific feature amount based on these components. The f1 is obtained by dividing a rotational frequency by a teeth number of the first rotating body and the XAB represents the least common multiple of the teeth numbers of the two rotating bodies.

Abstract: In order to adapt a balance piston unit of a compressor to a high speed, and to extend a service life of the compressor, a screw compressor according to the present invention includes a screw rotor including a rotor shaft, a radial bearing, a thrust plate, a balance mechanism, which is a slide bearing, a lubrication oil supply flow passage for supplying a lubrication oil, and a working fluid supply flow passage for supplying a working fluid for pressing the balance mechanism toward the thrust plate so that a reverse thrust load acts on the thrust plate.

Abstract: Provided is a screw compressor, accommodating a pair of rotatable male and female screw rotors in a compression chamber formed in a casing, wherein the casing includes: an internal dividing wall that defines an inside interior space; and an outer wall that defines an outside interior space arranged outside the inside interior space The screw compressor further includes: a communication pipe member that penetrates the outer wall and extends across the outside interior space, and an end of the communication pipe member being inserted into the internal dividing wall so that the inside interior space communicates with a passage outside the outer wall. By using this communication pipe member, fluid can pass across an interior space in the casing to be fed to another interior space formed further inside.

Abstract: Provided is a screw compressor, accommodating a pair of rotatable male and female screw rotors in a compression chamber formed in a casing, wherein the casing includes: an internal dividing wall that defines an inside interior space; and an outer wall that defines an outside interior space arranged outside the inside interior space The screw compressor further includes: a communication pipe member that penetrates the outer wall and extends across the outside interior space, and an end of the communication pipe member being inserted into the internal dividing wall so that the inside interior space communicates with a passage outside the outer wall. By using this communication pipe member, fluid can pass across an interior space in the casing to be fed to another interior space formed further inside.