Some embodiments are directed to a positive displacement pump having an eccentric piston, comprising a tube having a first end and a second end that is terminated by a cylinder secured to a delivery zone, the tube including an intake opening and a delivery opening, a drive shaft extending between the transmission zone and the tube, a piston arranged in the delivery zone and mounted in a sliding manner at the end of the shaft, being pressed against the cylinder by an elastic presser so as to prevent fluid displacement between the tube and the delivery zone when the pump is dry, and the elastic presser is provided to press the piston against the cylinder when the pump is running under load.

A pump-motor unit includes: a housing structure; an impeller for delivering a fluid; an electric drive motor accommodated in the motor space and including a rotor coupled to the impeller in order to rotationally drive it and a stator with a stator centring structure. The housing structure includes a pump space portion, a motor space portion, a housing centring portion axially between the pump space portion and the motor space portion, and a motor space opening on an end-facing side, through which the rotor and the stator can be axially inserted into the motor space. The housing centring portion encloses the stator centring structure in order to centre the stator.

A pump-motor unit includes: a housing structure; an impeller for delivering a fluid; an electric drive motor accommodated in the motor space and including a rotor coupled to the impeller in order to rotationally drive it and a stator with a stator centring structure. The housing structure includes a pump space portion, a motor space portion, a housing centring portion axially between the pump space portion and the motor space portion, and a motor space opening on an end-facing side, through which the rotor and the stator can be axially inserted into the motor space. The housing centring portion encloses the stator centring structure in order to centre the stator.

A compressor may include first and second scrolls, an axial biasing chamber, and a modulation control valve. The second scroll includes an outer port and an inner port. The outer and inner ports may be open to respective intermediate-pressure compression pockets. The modulation control valve may be in fluid communication with the inner port, the outer port, and the axial biasing chamber. Movement of the modulation control valve into a first position switches the compressor into a reduced-capacity mode and allows fluid communication between the inner port and the axial biasing chamber while preventing fluid communication between the outer port and the axial biasing chamber. Movement of the modulation control valve into a second position switches the compressor into a full-capacity mode and allows fluid communication between the outer port and the axial biasing chamber while preventing fluid communication between the inner port and the axial biasing chamber.

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.

A plurality of external teeth of an inner rotor are formed such that an intake-side clearance is larger than a discharge-side clearance. The intake-side clearance denotes a minimum value of a clearance between an external tooth and an internal tooth defining an inter-teeth chamber which communicates with an intake port and in which an amount of change in volume during rotation of the inner rotor by a unit angle is maximized. The discharge-side clearance denotes a minimum value of a clearance between an external tooth and an internal tooth defining the inter-teeth chamber which at least partially overlaps with a partition wall a first discharge port and a second discharge port when the amount of change in volume per unit angle is maximized.

A cast for producing end plates for a pump assembly, the cast comprising a base portion and a pair of projections, the pair of projections providing material to machine bearing assembly housings for accommodating drive and idler shafts in the pump assembly. Also provided is an inner plate bushing for an end plate in a pump assembly, the inner plate bushing comprising a collar extending from a flange, the collar to be inserted into a mounting recess in the end plate with the flange seating flush with a surface of the end plate, the surface area of an end of the collar being larger than an inner surface of the flange.

A motor includes a rotor and a stator, the stator having a stator core and an electrical insulator assembly at each end of the stator core. The electrical insulator assemblies each have an outer wall part extending in a circumferential direction and facing a yoke of the stator core and a plurality of extending parts extending radially inward from the outer wall part and facing teeth of the stator core. The outer wall part has a radial thickness and includes a plurality of radial notches for guiding extensions of the stator winding between an inner peripheral surface and an outer peripheral surface of the outer wall part. The outer peripheral surface of the outer wall part adjacent to the notches is configured such that the radial thickness of the outer wall part gradually decreases toward the notch along a circumferential direction of the yoke.

A rotary compressor, comprising: a housing, comprising a lubricant oil storage part for containing lubricating oil; a compression mechanism disposed in the housing; a driving mechanism driving the compression mechanism, the driving mechanism comprising a rotation shaft, through-holes extending along the axial direction of the rotating shaft are disposed inside the rotating shaft, and the rotation shaft is in fluid connection with the lubricating oil storage part via the through-holes; and an oil level sensor in fluid connection with the through-holes inside the rotation shaft via a pressurized collection channel. Also disclosed is a rotation mechanism, comprising an oil level sensor in fluid connection with the through-holes inside the rotation shaft via the pressurized collection channel. Accurate and reliable detection of the lubricating oil in a compressor can be done using the pressurized collection channel and the oil level sensor, thus greatly saving cost and improving compressor reliability.

A rotary pump conversion unit for a drywall pump is provided. The rotary pump conversion unit may allow a rotating drive shaft to convert momentum into vertical movement of a driven shaft. The driven shaft may be used to pump drywall mud into a drywall mud applicator. A major benefit of the present device is that the present rotary pump conversion unit for a drywall pump, taper, flat finisher, corner unit, etc. may be used in connection with a motorized drill as opposed to having to manually pump the device.