To prevent generation of drain reliably without depending on a difference in ambient temperature where a compressor is installed. Provided is a gas compressor: having a compressor main body compressing a gas, a drive source driving the compressor main body, a controller controlling the rotation speed of the drive source according to the discharge pressure of the compressor main body, and a temperature detector detecting the temperature of a discharge gas of the compressor main body; and performing no-load operation with the rotation speed of the drive source as a lower limit rotation speed when the discharge pressure reaches an upper limit pressure higher than a set pressure. When detecting that the temperature detected by the temperature detector is equal to or lower than a predetermined temperature during the no-load operation, the controller causes the lower limit rotation speed of the drive source to a lower limit rotation speed at which the temperature of the discharge gas is higher than the predetermined temperature and which is higher than a lower limit rotation speed when the detected temperature is higher than the predetermined temperature.

To prevent generation of drain reliably without depending on a difference in ambient temperature where a compressor is installed. Provided is a gas compressor: having a compressor main body compressing a gas, a drive source driving the compressor main body, a controller controlling the rotation speed of the drive source according to the discharge pressure of the compressor main body, and a temperature detector detecting the temperature of a discharge gas of the compressor main body; and performing no-load operation with the rotation speed of the drive source as a lower limit rotation speed when the discharge pressure reaches an upper limit pressure higher than a set pressure. When detecting that the temperature detected by the temperature detector is equal to or lower than a predetermined temperature during the no-load operation, the controller causes the lower limit rotation speed of the drive source to a lower limit rotation speed at which the temperature of the discharge gas is higher than the predetermined temperature and which is higher than a lower limit rotation speed when the detected temperature is higher than the predetermined temperature.

An object of the present invention is to provide a scroll compressor with a simple configuration which is capable of preventing the occurrence of noise induced due to compressed air remaining in a discharge pipe flow backward and an orbiting scroll rotating reversely when stopping the compressor. To this end, there is provided a scroll compressor including a scroll type compressor body provided with an orbiting scroll and a fixed scroll; a motor that drives the compressor body; an inverter that drives the motor; a discharge pipe that connects a discharge port of the compressor body to an air tank storing air compressed by the compressor body; and a check valve that shuts off the compressed air flowing backward from the air tank in the discharge pipe, in which, when stopping the compressor body, the inverter controls a rotational speed of the motor driving the compressor body, in two steps at a first deceleration and a second deceleration lower than the first deceleration, from when a stop command is output until the compressor body stops.

An object of the present invention is to provide a scroll compressor with a simple configuration which is capable of preventing the occurrence of noise induced due to compressed air remaining in a discharge pipe flow backward and an orbiting scroll rotating reversely when stopping the compressor. To this end, there is provided a scroll compressor including a scroll type compressor body provided with an orbiting scroll and a fixed scroll; a motor that drives the compressor body; an inverter that drives the motor; a discharge pipe that connects a discharge port of the compressor body to an air tank storing air compressed by the compressor body; and a check valve that shuts off the compressed air flowing backward from the air tank in the discharge pipe, in which, when stopping the compressor body, the inverter controls a rotational speed of the motor driving the compressor body, in two steps at a first deceleration and a second deceleration lower than the first deceleration, from when a stop command is output until the compressor body stops.

A system comprising an electric motor, a compressor configured to be driven by the electric motor, a plurality of valves in fluid communication with an output of the compressor, a rotor disposed adjacent the valves and configured to spin as the valves control fluid movement toward the rotor, and a magnet is coupled to the rotor and configured to spin within a stator, wherein the compressor causes fluid to move through the valves thereby causing the rotor to spin the magnet, which in turn generates an electrical current.

A plurality of scroll compressors with different fixed volume indexes are connected in fluid parallel circuit and configured to selectively operate to maximize isentropic efficiency at different condensing temperatures. Different quantities of scroll compressors of different volume indexes may be selected based upon typical climate or geographic location environmental conditions to attempt to maximize efficiency. A controller may selectively operate different combinations of the compressors of different volume indexes bases up load demands and condensing temperature conditions, which may be determined in a variety of ways.

Provided is a scroll compressor which has a reduced noise vibration by minimizing an impact sound generated when the operation of the scroll compressor is stopped.

A control module for a refrigeration system includes a startup mode control module that receives an off time of a compressor and an ambient temperature, determines whether the off time and the ambient temperature indicate that the compressor is in a flooded condition, and selects, based on the determination, between a normal startup mode and a flooded startup mode. A compressor control module transitions from the flooded startup mode to the normal startup mode after a predetermined period associated with operating in the flooded startup mode and operates the compressor at a first speed in the normal startup mode and operates the compressor at a second speed less than the first speed in the flooded startup mode.

A control module for a refrigeration system includes a startup mode control module that receives an off time of a compressor and an ambient temperature, determines whether the off time and the ambient temperature indicate that the compressor is in a flooded condition, and selects, based on the determination, between a normal startup mode and a flooded startup mode. A compressor control module transitions from the flooded startup mode to the normal startup mode after a predetermined period associated with operating in the flooded startup mode and operates the compressor at a first speed in the normal startup mode and operates the compressor at a second speed less than the first speed in the flooded startup mode.

A system is provided for adjusting the volume ratio of a screw compressor. The system can use a port in a rotor cylinder to bypass vapor from the compression chamber to the discharge passage of the compressor. A valve can be used to open or close the port to obtain different volume ratios in the compressor.