A scroll expander, comprising: a housing; and an expansion mechanism provided in the housing. A back pressure chamber in fluid communication with a medium pressure chamber is provided in the expansion mechanism and is provided with at least one passage in fluid communication from the back pressure chamber to a low pressure region; the passage is configured such that: the passage is opened when the pressure in the back pressure chamber is lower than the pressure of the low pressure region, and is closed when the pressure in the back pressure chamber is higher than or equal to the pressure of the low pressure region. The scroll expander can avoid the problem of being unable to be started and to operate normally; and the scroll expander is simple in structure, easy to process and manufacture, and high in cost effectiveness.

A scroll expander, comprising: a housing; and an expansion mechanism provided in the housing. A back pressure chamber in fluid communication with a medium pressure chamber is provided in the expansion mechanism and is provided with at least one passage in fluid communication from the back pressure chamber to a low pressure region; the passage is configured such that: the passage is opened when the pressure in the back pressure chamber is lower than the pressure of the low pressure region, and is closed when the pressure in the back pressure chamber is higher than or equal to the pressure of the low pressure region. The scroll expander can avoid the problem of being unable to be started and to operate normally; and the scroll expander is simple in structure, easy to process and manufacture, and high in cost effectiveness.

A pneumatic wrench including a pneumatic motor that includes a rotor, a rotor housing, an endplate, and a wear plate. The rotor has an output shaft configured to rotate about an axis and a plurality of vanes that extend radially from the axis that compressed air exerts work against to drive the rotor. The rotor housing has a cavity configured to house the rotor, receive the compressed air, and direct the compressed air about the rotor and out of the rotor housing. The endplate is coupled to the rotor housing and configured to receive the output shaft. The endplate includes a channel that is in fluid communication with the cavity. The wear plate is disposed between the endplate and the rotor housing and defines an exhaust port between the cavity and the channel for directing airflow from the cavity to the channel in an axial direction.

Fluid delivery devices using a pair of meshed external gears, in spite of no reciprocating component for fluid delivery enabling low rotational vibration, the high noise due to the trapping phenomenon, and the teeth bouncing contact due to undesired large backlash heretofore afforded in the gear manufacturing process, restrict the employments in the industrial field requiring quiet environment such as electric motor vehicles or room services. Accordingly, a gear pump or motor or a gear refrigerating compressor comprising a shaft gear and a driven gear meshed rotatably within a gear chamber formed with a housing and opposite side walls, which delivers fluids from a inlet chamber to a outlet chamber; a backlash of the meshed gears having fluid-leak-tight clearance; a closed chamber provided in a internal portion of at least a side wall; an opening provided on a side wall from which a communication passage extends to a closed chamber; and at least a elastic disc capsule contained in the closed chamber, comprising a pair of concaved elastic disc plate abutted and sealed against each other with gas inside, of which occupying volume varies elastically subject to the fluid pressure therein enabling to absorb or expel the squeezed fluid in the trapped interstice during the trapping period of the interstice, whereby the fluid entrapped in the interstices isolated by the fluid-leak-tight backlash suppressing the pressure transmission inwardly or outwardly, whereof volumetric variation during the trapping period is compensated by the compression or expansion of the elastic disc capsule, suppressing pressure pulse and air bubble generation and eliminating the teeth bouncing contact, achieving a low noise, low vibration and high efficiency gear pump or motor or refrigerating compressor.

A pneumatic motor includes a stator having a stator inner wall including a dwell region and a rotor eccentrically disposed within the stator. The rotor is configured to rotate about the axis of rotation and includes a plurality of vanes disposed around the rotor. Each vane of the plurality of vanes is configured to slide within a respective slot formed in the outer surface of the rotor between a fully retracted position and a fully extended position as the rotor rotates about the axis of rotation to maintain contact with the stator inner wall. The stator inner wall has a radius relative to the axis of rotation that is substantially constant within the dwell region so that vanes of the plurality of vanes are in the fully extended position within the dwell region.

A system, apparatus, and method for attenuating pulsations in a pumping system.