Tapered stator designs are engineered in a positive displacement motor (PDM) power section to relieve stator stress concentrations at the lower (downhole) end of the power section in the presence of rotor tilt. A contoured stress relief (i.e. a taper) is provided in the stator to compensate for rotor tilt, where the taper is preferably more aggressive at the lower end of the stator near the bit.

A stator for a helical gear device includes a first section having first helically convoluted chamber with a set of radially inwardly extending lobes and a second section adjacent to the first section. The second section includes a stack of cutter disks. Each cutter disk includes a front surface, a rear surface, an interior surface defining a central opening extending from the front surface to the rear surface, a forward cutting edge, and a rearward cutting edge. The interior surface forms a same number of lobes for the central opening as the set of radially inwardly extending lobes in the first section. Each cutter disk is aligned along a common centerline, and each cutter disk is rotated slightly relative to each other to form a second helically convoluted chamber with a same pitch as the first helically convoluted chamber. The second helically convoluted chamber exposes, to materials passing through, portions of the forward cutting edge or the rearward cutting edge of each cutter disk.

An oil pump includes: a first core in which an inner rotor having external teeth and an outer rotor having internal teeth are housed; a housing having a recess in which the first core is held; a second core disposed in contact with the first core in an axial direction; and a cover having a holding hole in which the second core is held. The first core has a first recess/projection portion formed on a first axial end surface at a side opposite to an axial end surface opposing a bottom wall of the recess. The second core has a second recess/projection portion formed on a second axial end surface that is in contact with the first axial end surface. A gap is formed between opposing surfaces of the housing and the cover in a state where the first and second axial end surfaces are in contact with each other.

A rotary fluid pressure device, such as a low-speed, high-torque gerotor motor, is provided with a valve drive shaft that is partially inserted into and engaged with a main drive shaft as the main drive shaft engages a rotating output shaft and engages a rotating and orbiting star member of a positive displacement device. The device is also provided with a drive retainer configured to retain the engagement of the main drive shaft and the valve drive shaft.

The present invention aims to provide a long-life stator and a uniaxial eccentric screw pump provided with the stator, which enable a comparatively extended period of use by preventing damage of the stator due to repeating of attachment and removal to/from the uniaxial eccentric screw pump. A stator 20 includes an outer cylinder 30, and a stator main body 42 having flange-shaped gasket parts 46 and 47. The stator 20 includes fixing areas 24 and 25 to which the gasket parts 46 and 47 and the outer cylinder 30 are adhered. One or both of the outer cylinder 30 and the gasket parts 46 and 47 has a derricking part penetrating or being dented in axial directions X and made into such a shape where at least part of one of the outer cylinder and the gasket parts is fitted into the other.

Tapered stator designs are engineered in a positive displacement motor (PDM) power section to relieve stator stress concentrations at the lower (downhole) end of the power section in the presence of rotor tilt. A contoured stress relief (i.e. a taper) is provided in the stator to compensate for rotor tilt, where the taper is preferably more aggressive at the lower end of the stator near the bit.

A system and method for coupling a temperature monitoring system within a progressive cavity pump to combat dry-running. A temperature monitoring system for use in a progressive cavity pump for monitoring the internal temperature of an elastomeric stator. The temperature monitoring system includes a sleeve and a temperature sensor disposed therein. The sleeve is inserted into a shell portion of the stator before vulcanizing the elastomeric stator so that the sleeve is vulcanized to the elastomeric stator.

A progressive cavity pump for transporting a liquid containing solids comprises a helical rotor, a stator having an inlet and an outlet, within which the helical rotor is rotatably disposed about a longitudinal axis of the stator, and comprising a helical inner wall corresponding to the helical rotor. The helical rotor comprises a shape tapering down toward the outlet or inlet, and the helical rotor and stator are disposed relative to each other and implemented such that at least one chamber is formed for transporting the liquid, and the chamber is cut off by a constriction. The progressive cavity pump includes an adjusting device for adjusting a relative axial position of the helical rotor and stator, wherein the adjusting device is implemented for expanding the constriction between the helical rotor and stator.

Rotary positive displacement machines with trochoidal geometry that comprise a helical rotor that undergoes planetary motion within a helical stator are described. The rotor can have a hypotrochoidal cross-section, with the corresponding stator cavity profile being the outer envelope of the rotor as it undergoes planetary motion, or the stator cavity can have an epitrochoidal cross-section with the corresponding rotor profile being the inner envelope of the trochoid as it undergoes planetary motion. In some multi-stage embodiments, the rotor-stator geometry remains substantially constant along the axis of the rotary machine. In other multi-stage embodiments, the rotor-stator geometry varies along the axis of the rotary machine.

A hybrid elastomer/metal on metal motor for a helical gear device includes a rotor and stator comprising a hydraulic motor that produces work when a working fluid is pumped therethrough. The improvement involves the stator being, for part of its length, a conventional or even wall stator, using an elastomer to form a seal against the moving rotor. The stator's remaining length comprises a profiled rigid surface that forms a seal directly with the moving rotor. This gives the motor the high efficiency of the elastomer sealing against the rotor, and simultaneously provides a backup of the stator's rigid section allowing continued motor operation at reduced efficiency, if the elastomer part failed in service. The invention also includes combinations of a regular disk stack with a rubber lining, a rigid material disk stack (or unitized element) and a circular rigid sleeve which react to rotor sideloading while permitting proper rotor orbiting.