Pressure changing devices and methods of making and using the same are disclosed. One pressure changing device includes an elliptic cylinder and a piston that has an external surface with a trochoid cross-section. Another pressure changing device includes a piston and a rotating cylinder that has an internal surface with a trochoid cross-section. Another pressure changing device includes two fixed axes, one for rotation of one component and another for orbiting or oscillation of the other component. The devices and methods include stacked pressure changing devices with one or more common shafts. The pressure changing device may be easier and less expensive to manufacture and repair than prior pressure changing devices of the same or similar functionality, and can provide efficient gap sealing in a high-pressure expansion part of a compression or expansion cycle.

A rotor and/or stator dampening system includes a stator and/or rotor with a liner selected of one or more materials to achieve a desired dampening effect. In one implementation, a progressive cavity motor or pump includes a stator with an internal axial bore therethrough. The stator has a liner along an axial length thereof with an inwardly facing surface defining the internal axial bore therethrough. The liner has a plurality of axial sections with at least two of the plurality of axial sections being constructed of different materials. A compression resistant mechanism, such as a spring or spring-like device, is disposed within at least one of the axial sections of the liner. The progressive cavity motor or pump also includes a rotor that is disposed and is rotatable within the internal axial bore of the stator to form a moving chamber between the rotor and the stator.

A fluid displacement apparatus includes a stator section with a rotor therein. The stator section includes a cylindrical casing, a helically-convoluted chamber section within the cylindrical casing, and a rigid sleeve within the cylindrical casing and separate from the helically-convoluted chamber section. The rigid sleeve includes a circular internal bore. The rotor is rotatably disposed within the cylindrical casing. The rotor includes a helically-lobed section disposed within the helically-convoluted chamber section, and a circular cylinder section disposed within the rigid sleeve. The circular cylinder section provides a fluid passageway between the rigid sleeve and the circular cylinder section. Side loads from the rotor are distributed along a contact line at any point of rotation of the circular cylinder section within the rigid sleeve.

An internal gear pump includes an outer rotor having internal teeth, an inner rotor rotatably disposed inside the outer rotor and having external teeth engaging with the internal teeth, and a pump housing. The pump housing includes: a holding recess rotatably holding the outer rotor and having a wall on which an outer peripheral face of the outer rotor is to slide; an inlet to take in a fluid into pump chambers defined between the inner rotor and the outer rotor; an outlet to discharge the fluid from the pump chambers; a case groove provided on the wall and to hold the fluid; and a joint groove provided on an upper land face defined between a trailing end of the inlet and a leading end of the outlet and on which the internal teeth and the external teeth are to slide.

An internal gear pump includes an outer rotor having internal teeth, an inner rotor rotatably disposed inside the outer rotor and having external teeth engaging with the internal teeth, and a pump housing. The pump housing includes: a holding recess rotatably holding the outer rotor and having a wall on which an outer peripheral face of the outer rotor is to slide; an inlet to take in a fluid into pump chambers defined between the inner rotor and the outer rotor; an outlet to discharge the fluid from the pump chambers; a case groove provided on the wall and to hold the fluid; and a joint groove provided on an upper land face defined between a trailing end of the inlet and a leading end of the outlet and on which the internal teeth and the external teeth are to slide.

The present disclosure relates to a rotary engine having a crankshaft with an improved structure, the rotary engine including a housing, a rotor, housing covers, and a crankshaft installed to penetrate through the rotor so as to receive rotational force from the rotor, wherein the crankshaft includes a first member extending in one direction and having an insertion groove recessed in one side surface thereof, a second member extending to penetrate through a center portion of the housing and provided with a protruding portion on one end thereof to be fixedly inserted into the insertion groove, and a coupling member interposed at a position where the insertion groove and the protruding portion overlap each other such that the first member and the second member are closely coupled to each other.

The present disclosure relates to a rotary engine having a crankshaft with an improved structure, the rotary engine including a housing, a rotor, housing covers, and a crankshaft installed to penetrate through the rotor so as to receive rotational force from the rotor, wherein the crankshaft includes a first member extending in one direction and having an insertion groove recessed in one side surface thereof, a second member extending to penetrate through a center portion of the housing and provided with a protruding portion on one end thereof to be fixedly inserted into the insertion groove, and a coupling member interposed at a position where the insertion groove and the protruding portion overlap each other such that the first member and the second member are closely coupled to each other.

A stator assembly for a progressive cavity pump or a progressive cavity motor includes connectors for connecting functional elements and at least one stator, the stator including an outer pipe as well as a lining subject to wear which is disposed inside the outer pipe, the at least one stator being disposed between the connectors such that a cavity extending across the entire stator assembly for housing a rotor is created. Between at least one of the connectors and at least one stator adjacent thereto and/or between adjacent stators an adhesion region is provided, whereby in the adhesion region an adhesive is disposed in such a way that between the at least one connector and the at least one stator adjacent thereto and/or between said respectively adjacent stators a substance-to-substance connection is created.

Sealing in rotary positive displacement machines based on trochoidal geometry that comprise a helical rotor that undergoes planetary motion within a helical stator is described. Seals can be mounted on the rotor, the stator, or both. 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 embodiments, the geometry is offset in a manner that provides advantages with respect to sealing in the rotary machine. In multi-stage embodiments, the rotor-stator geometry remains substantially constant or varies along the axis of the rotary machine.

A linear energy harvesting device that includes a housing and a piston that moves at least partially through the housing when it is compressed or extended from a rest position. When the piston moves, hydraulic fluid is pressurized and drives a hydraulic motor. The hydraulic motor drives an electric generator that produces electricity. Both the motor and generator are central to the device housing. Exemplary configurations are disclosed such as monotube, twin-tube, tri-tube and rotary based designs that each incorporates an integrated energy harvesting apparatus. By varying the electrical characteristics on an internal generator, the kinematic characteristics of the energy harvesting apparatus can be dynamically altered. In another mode, the apparatus can be used as an actuator to create linear movement. Applications include vehicle suspension systems (to act as the primary damper component), railcar bogie dampers, or industrial applications such as machinery dampers and wave energy harvesters, and electro-hydraulic actuators.