A multistage pump body comprises a first pumping chamber (20) and a second pumping chamber (21). A connecting duct (26a) puts an outlet (27) of the first pumping chamber (20) into communication with an inlet (28) of the second pumping chamber (21). A leak-tight conduit (40) is provided for the circulation of a cooling liquid. The connecting duct (26a) is a lateral duct of the multistage pump body. A heat-conducting wall (33) partially delimits the connecting duct (26a) and has an external surface (34) on the outside. At least a portion of the connecting duct (26a) passes between this external surface (34) of the heat-conducting wall (33) and the leak-tight conduit (40).

A multistage pump body comprises a first pumping chamber (20) and a second pumping chamber (21). A connecting duct (26a) puts an outlet (27) of the first pumping chamber (20) into communication with an inlet (28) of the second pumping chamber (21). A leak-tight conduit (40) is provided for the circulation of a cooling liquid. The connecting duct (26a) is a lateral duct of the multistage pump body. A heat-conducting wall (33) partially delimits the connecting duct (26a) and has an external surface (34) on the outside. At least a portion of the connecting duct (26a) passes between this external surface (34) of the heat-conducting wall (33) and the leak-tight conduit (40).

A gas compressor includes a compression mechanism, a separator tank that introduces lubricating oil to be supplied to the compression mechanism and a mixed fluid of a working fluid and the lubricating oil discharged from the compression mechanism and separates the lubricating oil, an oil cooler that cools the lubricating oil from the separator tank, an oil circulation path that supplies the cooled lubricating oil to the compression mechanism, and a motor that drives the compression mechanism and is isolated from the oil circulation path. Further, the gas compressor includes a suction temperature sensor that detects a suction temperature of the working fluid, a discharge pressure sensor that detects a discharge pressure of the compressed working fluid, a rotation speed sensor that detects a rotation speed of the motor, and a lubricating oil state estimation unit that estimates a temperature of the lubricating oil based on the detected suction temperature, discharge pressure, and rotation speed of the motor, in which the lubricating oil state estimation unit estimates a deterioration state of the lubricating oil based on the estimated temperature of the lubricating oil.

A gas compressor includes a compression mechanism, a separator tank that introduces lubricating oil to be supplied to the compression mechanism and a mixed fluid of a working fluid and the lubricating oil discharged from the compression mechanism and separates the lubricating oil, an oil cooler that cools the lubricating oil from the separator tank, an oil circulation path that supplies the cooled lubricating oil to the compression mechanism, and a motor that drives the compression mechanism and is isolated from the oil circulation path. Further, the gas compressor includes a suction temperature sensor that detects a suction temperature of the working fluid, a discharge pressure sensor that detects a discharge pressure of the compressed working fluid, a rotation speed sensor that detects a rotation speed of the motor, and a lubricating oil state estimation unit that estimates a temperature of the lubricating oil based on the detected suction temperature, discharge pressure, and rotation speed of the motor, in which the lubricating oil state estimation unit estimates a deterioration state of the lubricating oil based on the estimated temperature of the lubricating oil.

A method of operating exhaust gas recirculation pump for an internal combustion engine including: providing an EGR pump assembly including an electric motor coupled to a roots device having rotors, the EGR pump operably connected to an internal combustion engine; providing an EGR control unit linked to the EGR pump assembly; providing sensors linked to the EGR control unit; determining if a motor speed is within a predetermined target in step S1 wherein when motor speed=predetermined target then; determining if a motor torque is within a predetermined target in step S2 wherein when motor torque=predetermined target then; determining if a motor temperature is within a predetermined target in step S3 wherein when motor temperature=predetermined target then; and maintaining operation of the exhaust gas recirculation pump.

A volumetric gear machine interacting with a working fluid comprising: a first toothed wheel (3) with helical teeth comprising a first tooth (31) in turn comprising a first and a second flank (311, 312) opposite each other; a second toothed wheel (4) with helical teeth having two opposite flanks, the first and the second wheel (3, 4) being operatively coupled in a meshing area (2). At a portion of the meshing area (2), the first and the second flank (311, 312) being in simultaneous contact with the second wheel (4).

A driving structure of a three-axis multi-stage Roots pump comprises a pump body, wherein a gear end cover is mounted at one side of the pump body, an air outlet end moving bearing air sealing unit is mounted on the other side of the pump body, and the bearing end cover is mounted on the pump at the side of the pump body; a driving axis, a first driven axis and a second driven axis are further provided inside the pump body, and the driving axis is connected with the first driven axis and the second driven axis through the gear, respectively; and both ends of the driving axis, the first driven axis and the second driven axis are movably connected to an air inlet end gear mechanical seal driving unit and an air outlet end moving bearing air sealing unit, respectively. The present invention overcomes the deficiencies of the prior art, a fixed bearing limiting unit not only plays a radial supporting role, strengthens the rigidity of an independent axis, but also reduces the diameter of the axis, and at the same time, evenly distributes to the two axial ends in the axial deformation process, avoiding deformation in a single direction, reducing the amount of displacement by nearly half, and also improving the sealing efficiency of the system.

The present invention effectively cools air in a compression process at a high stage when an oil is supplied at the same pressure at a low stage and the high stage. Provided is a liquid-cooled type compressor including: a liquid-cooled type compressor body; at least one first nozzle; and at least one second nozzle, the at least one first nozzle and the at least one second nozzle each having a plurality of injection ports per nozzle and supplying a refrigerant through the injection ports into an inside of the compressor body, the second nozzle having the injection ports each having a diameter larger than a diameter of each of the injection ports of the first nozzle.

A structure of rotor connection of multi-axial multi-stage roots pump comprises a rotor body, a rotor shaft is arranged on one end face of the rotor body, a sub-shaft cavity is opened in the rotor shaft, and the locating keyways are symmetrically opened on both sides inside the sub-shaft cavity; a sub-shaft is arranged on the other end face of the rotor body, the sub-shafts and the sub-shaft cavities of two adjacent rotor bodies are matched, locating keyways are symmetrically opened on both sides of the sub-shaft, and the keyways are installed and fixed through sub-rotor shaft keys in the locating keyways. The invention overcomes the disadvantages of the prior art, and the first-stage rotor body is limited and fixed by the bearing, while the second-stage rotor body is only radially limited by the bearing in the first-stage rotor body. The rotor shaft on the other side is also fixed and limited by the bearing, so the thermal expansion displacement and thermal stress of the second-stage rotor body are completely independent during operation. The thermal expansion displacement of the first-stage rotor body does not affect the second-stage rotor body, and it can also synchronously drive the second-stage rotor body.

Exhaust gas recirculation pump (30) for an internal combustion engine that includes an electric motor (32) disposed within a housing (36). A Roots device (38) is coupled to the electric motor (32) and includes a housing (40) defining an internal volume (42) in which rotors (44) are disposed and are connected to the electric motor (32). The electric motor housing (36) includes a coolant path (48) formed therein which extends from a coolant inlet (58) to a coolant outlet (78), both coupled to an engine coolant circulation system. The housing includes an oil path (108) formed therein. The oil path includes an oil inlet (110) extending to at least one oil outlet (112). The oil inlet and outlet are coupled to an engine oil circulation system wherein the oil path (108) lubricates bearings (100) and a transmission assembly (46) of the exhaust gas recirculation pump (30).