The present disclosure relates to a pumping assembly, a piston pump and an oral irrigator. The pumping assembly includes: a cylinder, cavities providing therein with at least two cavities with different inner diameters; a piston mechanism successively extending through the at least two cavities, the piston mechanism being in slidable cooperation with walls of the cavities, and a gap being formed between a sidewall of part of the piston mechanism and the walls of the cavities; and a drive mechanism connected to the piston mechanism, the drive mechanism being configured to drive the piston mechanism to move.

A pump comprises a housing (141) having a cavity (142) with an inlet valve (143), an apparatus (144) for raising fluid pressure in the cavity (142) and a discharge valve (145), the discharge valve (145) comprises a valve head (160) movable between an open and closed position and a valve seat (167), wherein the pump further comprises a booster piston (182) arranged in a booster cylinder (183), the booster piston (182) has a first face (191) exposed to a low pressure zone (189) and a second face (194) exposed to fluid pressure in the cavity (142), and at least one of the booster piston (182) and the booster cylinder (183) is movable relative to the other to add an opening force to the discharge valve. The pump is preferably a mud pump for circulating drilling mud through a drill string in a wellbore or a cement pump which may be of the type for pumping cement into a wellbore. Also disclosed is a method for facilitating opening a valve comprising a valve head (160) and a valve seat (167), the valve head (160) is movable a predetermined distance from a closed position on the valve seat (167) to a fully open position distant on the valve seat, and the method comprises the step of adding a force to the valve head (160) along a small portion of the predetermined distance.

A pump body of a high-pressure pump includes a pressure chamber formed in a deep portion of a cylinder. The pump body closes the pressure chamber on a side opposite to a plunger. The plunger reciprocates within the cylinder to vary a volume of the pressure chamber. The large-diameter portion provided at an end of the plunger on a side protruding to the pressure chamber has an outside diameter larger than an inside diameter of the cylinder and smaller than an inside diameter of the pressure chamber. In this case, the large-diameter portion is engaged with a step portion between the cylinder and the pressure chamber in a state before attachment of the high-pressure pump to an internal combustion engine. Accordingly, separation of the plunger from the cylinder is avoidable.

Various assemblies that can be used in a mud pump with a plunger-style piston to reduce seal failures, to offer control in variability of the circumference of the piston to thereby control fluid pressure, and to provide visibility into seal condition during operation. In one embodiment, a sleeve that can vary the overall effective circumference of the piston enables fluid pressure control. In some embodiments, seal failure within a pump can be monitored via a drain port that would receive drilling fluid leaking past a seal during operation of the pump. A discharge valve can be provided between an inlet and an outlet of the mud pump to reduce the load on pump components during start-up. Additional systems, devices, and methods are also disclosed.

A plasma compression driver is connected to a plasma containment vessel containing a liquid medium that forms a liquid liner containing plasma, and comprises a pair of coaxially aligned pistons that are sequentially driven towards the liquid liner. A pusher bore containing a pusher piston is coaxial with and has a smaller diameter than a driver bore containing a driver piston such that an interconnecting annular face surface is defined at the junction of the driver and pusher bores. During the compression operation, a prime mover accelerates the driver piston towards the pusher piston and compresses a compression fluid, which accelerates the pusher piston and pushes the liquid medium in the pusher bore into the vessel, causing the liquid liner to collapse, and compressing the plasma. Outward forces on the vessel wall caused by compression driver recoil and increased vessel pressure is counteracted by an inward force applied by the compression fluid on the annular face surface during the compression operation.

A retainer assembly and plug for a fluid end of a pump system includes a retainer body. A plurality of tongues are movably arranged about the retainer body. The tongues are moveable between a pre-installed configuration and an installed configuration depending on the position of the retainer body relative to the tongues. In the installed configuration engaging flanges of the tongues are positioned in a retaining channel formed in a bore of the fluid end and retain the retainer assembly to the fluid end. A plug is configured to sealingly fit to the bore of the fluid end inboard of the retainer assembly and a locking mechanism is configured to secure the retainer assembly to the plug, and when so secured, the position of the retainer body is maintained relative to the plurality of tongues and the retainer assembly is maintained in the installed configuration.

A hydraulic pump/motor includes: a cylinder block rotating about a rotation axis; a piston in a cylinder bore; and a valve plate facing a cylinder port. The valve plate includes: a high pressure port through which hydraulic oil discharged from the cylinder port flows; a low pressure port through which the oil to be sucked into the cylinder port flows; a region disposed between the high and low pressure ports in a circumferential direction of the rotation axis and including a top dead center position facing the cylinder port of the cylinder bore in which the piston moved to a top dead center is disposed; and a residual pressure release port between the top dead center position and the low pressure port in the region. The residual pressure release port includes first and second ports disposed at a positions different from each other in the radial direction of the rotation axis.

A plasma compression driver is connected to a plasma containment vessel containing a liquid medium that forms a liquid liner containing plasma, and comprises a pair of coaxially aligned pistons that are sequentially driven towards the liquid liner. A pusher bore containing a pusher piston is coaxial with and has a smaller diameter than a driver bore containing a driver piston such that an interconnecting annular face surface is defined at the junction of the driver and pusher bores. During the compression operation, a prime mover accelerates the driver piston towards the pusher piston and compresses a compression fluid, which accelerates the pusher piston and pushes the liquid medium in the pusher bore into the vessel, causing the liquid liner to collapse, and compressing the plasma. Outward forces on the vessel wall caused by compression driver recoil and increased vessel pressure is counteracted by an inward force applied by the compression fluid on the annular face surface during the compression operation.

A plunger pump, including: a tubular cylinder that has an internal space communicating with inlet and outlet flow paths; and a piston that is movable along an axis of the cylinder, wherein a head of the piston includes, on an outer peripheral surface thereof, a sealing portion that is slidable against an inner peripheral surface of the cylinder, which includes a body tubular portion wherein the head is arranged during normal use, and a cleaning tubular portion wherein the head is arranged during cleaning, an inner peripheral surface of the cleaning tubular portion has an inner diameter equal to that of an inner peripheral surface of the body tubular portion, the cleaning tubular portion includes, on the inner peripheral surface thereof, at least one cleaning liquid circulation groove that is configured by a through hole or recess, and the cleaning liquid circulation groove extends obliquely with respect to the axis.

A fluid end assembly comprising a plurality of fluid end sections positioned in a side-by-side relationship. Each fluid end section comprises a housing made of multiple-piece construction. One or more pieces of the housing are configured to have a plurality of stay rods attached thereto. The stay rods interconnect the fluid end assembly and a power end assembly.