A fluid compressor includes a case, a fixed scroll, an orbiting scroll, a motor, and at least one anti-rotation unit. The case is configured to form an external appearance thereof. The fixed scroll is fixed in the case. The orbiting scroll is engaged with the fixed scroll at one side of the fixed scroll, and performs partitioning of a compression chamber. The motor provides the orbiting scroll with drive power. The anti-rotation unit is coupled to a side surface of the orbiting scroll so as to prevent rotation of the orbiting scroll.

Detection of reverse rotation or operation of a refrigerant compressor is provided. In one aspect, a detection technique includes starting the compressor and determining the compressor is rotating in a reverse direction if a dome temperature of the compressor fails to exceed a first predetermined threshold at or before expiration of a first predetermined period of time following starting, the refrigerant pressure at a refrigerant inlet of the compressor remains constant for a second predetermined period of time following starting, and/or the frequency of pressure oscillations of the refrigerant at the refrigerant inlet exceeds a second predetermined threshold. Another technique for determining the compressor is rotating in the reverse direction involves analyzing a waveform associated with motor current, motor torque, or refrigerant pressure. Further embodiments, forms, features, and aspects shall become apparent from the description and drawings.

A compressor fault diagnostic apparatus including a current sensing unit to sense a current flowing through a motor of the compressor, a fault diagnostic unit to determine whether or not the motor performs a reverse rotation based on the current flowing through the motor, and a cut-off unit to remove power based on a determination of the fault diagnostic unit.

An object of the present invention is to provide a rotary displacement compressor capable of determining whether a check valve has failed, and preventing the life of a compressor body from being reduced when a compression operation stops. In order to achieve the object, a rotary displacement compressor includes a compressor body that compresses a medium by reducing a volume of the medium using rotation; a discharge pipe through which a compressed medium, which is discharged through a discharge port of the compressor body, flows; a check valve that shuts off the compressed medium flowing backward to the compressor body; and a backflow control valve that allows a predetermined rate of the compressed medium to flow backward. The check valve and the backflow control valve are disposed in series via the discharge pipe.

Methods and systems for detecting and correcting improper operation of a compressor in a refrigeration system and/or an HVAC system include a component level detection and prevention and a system level detection and prevention. The system level detection and prevention can be a backup or a confirmation of the component level detection and prevention. The component level detection and prevention can detect and prevent improper compressor operation within a predetermined time so that the compressor's operation period in an improper direction can be minimized, thereby minimizing wear and damage to the compressor.

The present invention corresponds to a check valve with an inertial mass that is installed in the bottom of the production tubing and above the progressive cavity pump (PCP) of an oil well, which prevents that the hydrostatic column that is inside of the production tubing go down in the moment where the artificial lift of the column stops for the detention of the PCP pump. If we prevent that this phenomenon to happen, the PCP pump will not rotate in the opposite direction of its normal operation and it will not be clogged by any particulate material that is contained in it.

A scroll compressor includes a movable scroll having first key grooves, a stationary member having second key grooves, and an Oldham coupling provided between the movable scroll and the stationary member. The Oldham coupling is movable with respect to the stationary member along a first axis direction, and with respect to the movable scroll along a second axis direction. The second axis is orthogonal to the first axis and passes through a center of gravity of the Oldham coupling. The Oldham coupling has an annular body portion, at least two first key portions fitted into the first key grooves, and second key portions fitted into the second key grooves. Key gaps are formed between outer peripheral surfaces of the first key portions and inner peripheral surfaces of the first key grooves. The key gaps have first gaps and second gaps wider than the first gaps.

A compressor fault diagnostic apparatus including a current sensing unit to sense a current flowing through a motor of the compressor, a fault diagnostic unit to determine whether or not the motor performs a reverse rotation based on the current flowing through the motor, and a cut-off unit to remove power based on a determination of the fault diagnostic unit.

An electric compressor includes a compression portion discharging a high pressure refrigerant by compressing a low-pressure drawn refrigerant, an electric motor driving the compression portion with a rotation of a rotor, a motor drive circuit driving the electric motor, an intermediate pressure port through which an intermediate pressure refrigerant is introduced into the compression portion, and a controller performing a rotation control of the rotor. When the controller stops the electric motor in a two-step compression mode in which the intermediate pressure refrigerant is introduced into the compression portion, the controller stops the rotor rotating by performing short-circuit braking on the electric motor and then fixes a rotational position of the rotor at a predetermined rotational position by performing direct current excitation on the electric motor.

Methods and systems for detecting and correcting improper operation of a compressor in a refrigeration system and/or an HVAC system include a component level detection and prevention and a system level detection and prevention. The system level detection and prevention can be a backup or a confirmation of the component level detection and prevention. The component level detection and prevention can detect and prevent improper compressor operation within a predetermined time so that the compressor's operation period in an improper direction can be minimized, thereby minimizing wear and damage to the compressor.