An electric compressor includes a housing, a drive shaft, a motor, a fixed scroll, a movable scroll, and a fixed block. The fixed block is fixed to the housing and disposed between the motor and the movable scroll. The motor includes a stator and a rotor. The rotor has an introduction passage that is formed through the rotor in an axial direction of the drive shaft. The drive shaft includes a balance weight that is disposed between the fixed block and the motor. The balance weight extends to a position where the balance weight covers at least a part of the introduction passage in a radial direction of the drive shaft in a view in the axial direction of the drive shaft. The balance weight is located away from the rotor by a predetermined distance in the axial direction of the drive shaft.

A scroll compressor includes a housing; a motor provided in the housing; a rotating shaft rotated by the motor; an orbital scroll orbital moved by the rotating shaft; and a fixed scroll forming a compression chamber together with the orbital scroll, wherein the fixed scroll includes an injection hole guiding an intermediate pressure refrigerant to the compression chamber, wherein the compression chamber is formed in a pair, and wherein the injection hole is formed to communicate with any one of the pair of compression chambers when communicating with the other one of the pair of compression chambers. Thereby, an amount of refrigerant discharged from the compression chamber is increased, and thus the performance and efficiency of the compressor may be improved.

A scroll compressor of an air conditioner includes a refrigerant discharge tube through which refrigerant discharged to an inner space of a casing is discharged into a refrigeration cycle, a venturi tube disposed adjacent to the refrigerant discharge tube in the inner space of the casing, and a liquid refrigerant discharge tube having a first end connected to the venturi tube and a second end opposite to the first end and communicating with the inner space of the casing at a lower side of the refrigerant discharge tube, where liquid refrigerant can be suppressed from excessively stagnating in the inner space of the casing.

A compressor includes a compression mechanism, an electric motor unit, a drive shaft and a housing. A portion of the drive shaft, which is located on one side in an axial direction, is rotatably supported by a main bearing, which is formed integrally in one-piece with or is fixed to a main bearing member of the compression mechanism. Another portion of the drive shaft, which is located on another side in the axial direction, is rotatably supported by a sub-bearing, which is formed integrally in one-piece with or is fixed to an inside of a body portion of a sub-bearing member. The sub-bearing member is formed separately from the housing and is fixed to a bottom surface of a bottom portion of the housing.

A hydraulic pump includes a casing, an impellor pump comprising a rotor that is rotationally mobile with respect to the casing about a first axis, the rotor comprising several blades in helix form, a transition zone belonging to the casing and having, on the side of the impellor pump, a ramp in helix form developing in the same direction as the helix form of the blades, a trochoid pump comprising a rotor with outer toothing secured to the rotor of the impellor pump, and a rotor with internal toothing that is rotationally mobile with respect to the casing about a second axis parallel to and offset from the first axis, the trochoid pump being fed by the impellor pump through the transition zone running along the ramp.

A split power gerotor pump includes a rotational axis, a shaft, an inner gerotor, an eccentric pocket, and an outer gerotor. The inner gerotor is rotationally fixed on the shaft, rotatable about the rotational axis, and includes n first lobes. The eccentric pocket is rotatable about the rotational axis, and includes a cylindrical bore with a center radially offset from the rotational axis and an outer surface, disposed radially outside of the cylindrical bore and arranged for direct engagement with a gear or a rotor for an electric motor. The outer gerotor includes a cylindrical outer surface installed in the cylindrical bore and n+1 second lobes.

An inner gear includes: sliding surface parts that are provided annularly at an outer peripheral part including a plurality of outer teeth on both sides of the inner gear in its axial direction and that slide on a pump housing; recessed parts that are respectively provided radially inward of the sliding surface parts to respectively form fuel chambers, into which fuel flows, between the recessed parts and the pump housing; and a communication hole that communicates between the recessed parts. The inner gear further includes an inclined surface part that is provided at an edge portion of a communicating edge portion on a rotation advance side of the inner gear, to avoid an adjacent part adjacent to an inner peripheral edge portion of each of the sliding surface parts and that is inclined further toward a rear side in a direction to a central part of the communication hole.

An electrically driven positive displacement compressor includes an electric drive motor configured to drive the compressor, the electric drive motor including a ring shaped electric stator and an electric rotor arranged inside the ring shaped electric stator and defining a cavity within the electric rotor. The compressor also includes a working chamber having an inlet and an outlet, the working chamber being arranged at least partially inside the cavity of the electric rotor. The compressor additionally includes a compressor rotor arranged inside the working chamber and coupled to the electric rotor.

A stepping motor-driven system includes a stepping motor, an output device, and a belt and pulley system operably coupling the stepping motor with the output device to impart rotation therebetween. The belt and pulley system includes an input pinion engaged with the stepping motor, an output pinion engaged with the output device, and a timing belt. The timing belt is disposed about the input and output pinions, inhibits elongation, and defines a plurality of spaced-apart grooves on an inwardly-facing surface thereof that are wider than the teeth of the pinions and are configured to receive the teeth of the pinions in meshed engagement therewith. As a result, a gap is defined within each groove. The gaps permit backlash of the timing belt in response to changes in a rotational speed input to the belt and pulley system from the stepping motor, thereby inhibiting loss of control.

A fluid pump includes a pump head and a motor coupled by a drive shaft. The pump head includes a pump inlet, a pump outlet, and a pumping stage in which a movable pump element is driven by the drive shaft. The motor includes a motor rotor and a motor stator. A connector couples the motor rotor and the drive shaft. The connector includes a plate rotatable with the drive shaft, fan blades attached to the plate for establishing a flow of air for cooling the motor, and one or more counterweights attached to the plate for reducing or eliminating imbalance created by certain forces generated by the pump during operation.