A piston pump is described for pumping a fluid. The pump includes at least one cylinder having a piston movable inside the cylinder along the longitudinal axis of the cylinder by a drive, each cylinder having at an end face a mounting flange having at least one cylinder opening, and a chamber having a volume that changes when the associated piston is moved in the cylinder. The piston pump has an inlet port for supplying and an outlet port for draining the fluid. A rotatable valve plate is arranged on the other side of the mounting flange. The mounting flange has at least one passage in the region of the inlet port and the outlet port, respectively, through which the fluid can flow between the inlet port and/or the outlet port and the other side of the mounting flange. The valve plate has fluid-transporting means by which, upon rotation of the valve plate at least one cylinder opening can be connected to a passage of the inlet and/or the outlet port.

A volumetric pump comprising a product metering piston 28 mounted inside a metering chamber 22 so as to slide, a sleeve 14 at least partially delimiting an intake chamber 16 and an exhaust chamber 18 for the product, and a product dispensing means 24 is provided. The dispensing means comprises an intake member 34 comprising product passage means 44d that are able to at least partially face an inlet orifice 48 of the metering chamber, and an exhaust member 36 comprising product passage means 50d that are able to at least partially face an outlet orifice 54 of said chamber. The intake and exhaust members are situated axially on either side of an internal partition 42 of the sleeve and are each mounted so as to bear axially against said partition.

A volumetric pump comprising a product metering chamber 22, a metering piston 28 mounted inside said chamber so as to slide between top dead center and bottom dead center, a sleeve 14 at least partially delimiting an intake chamber 16 and an exhaust chamber 18 for said product, and a product dispensing means 24 that is mounted so as to be able to move with respect to the sleeve and is able to place the metering chamber alternately into communication with the intake chamber and the exhaust chamber is provided. The pump also comprises a measuring means 60 that is able to measure the pressure of the product inside the metering chamber 22, and a control unit 62 that is connected to the measuring means 60 and is able to verify the presence of pressure peaks exhibiting a value greater than or equal to a predetermined pressure threshold.

A rotary pump for a fluid metering system is provided. The rotary pump reciprocates, and is reversed by a signal from a limit switch that is deflected by an actuator arm on a rotating sleeve of the pump system. The sleeve receives a gasket that forms a seal between the sleeve and the housing, the gasket having an opening surrounding a side hole of the sleeve to permit fluid to pass through the side hole between a pump volume and an inlet port or outlet port of the housing.

A rotary pump for a fluid metering system is provided. The rotary pump reciprocates, and is reversed by a signal from a limit switch that is deflected by an actuator arm on a rotating sleeve of the pump system.

The object of the present invention is to provide a fluid rotary machine in which dead spaces can be reduced as much as possible even if the machine is enlarged by arranging rotary valves directly behind cylinder chambers. The fluid rotary machine in which first and second double-headed pistons (7, 8) intersecting within a case body (1, 2) move linearly back and forth within cylinders (16) due to the hypocycloid principle along with rotation of shafts (4a, 4b) and in which intake and exhaust cycles are repeated in chambers (22), wherein cylinder heads (17) for closing the cylinder chambers (22) are each provided with rotary valves (19) which are rotated by drive transmission from the shafts (4a, 4b) and which are provided with intake holes and discharge holes (19b) alternately communicated with the cylinder chambers (22) via communication channels (20a, 20b), and the rotary valves (19) intersect longitudinal axis of the opposing pistons (7, 8) and are capable of rotating parallel with output axil lines.

A combined pump-injector valve utilizing a single piece as the barrel of the pump and as the stator of the valve, thus eliminating any need for connections between a pump and a valve, and therefore the potential for high-pressure leaks or pressure reductions. The combined pump-injector valve permits injection of nanoliter-sized samples into a chromatographic column, which is sealed during loading of the sample and filling of the pump, such that complete analyses can be completed with microliters of mobile phase with nanoliters of a sample.

An inline pump assembly for dispensing fluids, the pump assembly including a pump head, having a piston wherein movement of the piston causes the pump head to dispense a fluid. A linear actuator has a lead screw wherein actuation of the linear actuator causes the lead screw to move along a linear path. A first anti-backlash device is disposed between the linear actuator and the pump head. The anti-backlash device includes a rail having a sliding block thereon. The slide block and rail are engaged to prevent movement of the slide block about a longitudinal axis of the rail. A coupler is fixedly secured to the linear slide and having a first end connected to the lead screw and a second end connected to the piston rod.