Abstract: A pump having two pistons which are driven by a cam belonging to an external rotor and which are inserted into two cylinder blocks mounted parallel to each other in such a way as to form two opposite, parallel, eccentric pump chambers The pump chambers have at least one inlet port through which liquid is drawn into the pump chambers during the fill stroke of the pistons, and then expelled from the pump chambers during the discharge stroke of the pistons to at least one outlet port, the outflow rate of which is constant and even.

Abstract: A pump having two pistons which are driven by a cam belonging to an external rotor and which are inserted into two cylinder blocks mounted parallel to each other in such a way as to form two opposite, parallel, eccentric pump chambers The pump chambers have at least one inlet port through which liquid is drawn into the pump chambers during the fill stroke of the pistons, and then expelled from the pump chambers during the discharge stroke of the pistons to at least one outlet port, the outflow rate of which is constant and even.

Abstract: A pump having two pistons placed in a rotor, situated in a stator forming two opposite parallel eccentric pumping chambers having at least one inlet port through which the fluid is drawn into at least one of the pumping chambers during the filling movement of at least one of the pistons and, subsequently, expelled from at least one of the pumping chambers, during the emptying movement of at least one of the pistons, to at least one outlet port, characterized by an inlet cavity in connection with the inlet port, an outlet cavity in connection with the outlet port and two port changeover transition zones situated between each side of the cavities.

Abstract: A pump having two pistons which are parallel and in opposition and are disposed in two, cylindrical, cavities in a pump body, including at least one inlet port and at least one outlet port connected to a rotational port-switching device which can move axially along its rotational axis and is held in abutment in the pump body by a restoring member, in the form of a spring.

Abstract: The pump includes a housing containing a hollow elongated part, a piston arranged to move back and forth inside an elongated part, an inlet port and an outlet port arranged so that a fluid can be sucked through the inlet port into a chamber during an instroke of the piston and expelled through the outlet port during an outstroke. A linearly and/or angularly actuable valve system has a valve holder mounted on the pump housing which includes at least one through-hole extending from the piston chamber to the housing outer surface. The valve holder contains an inlet and/or outlet to alternately connect the inlet and outlet ports of the volumetric pump.

Abstract: A volumetric pump comprises at least one piston inside a cylindrical housing and means to cause a relative to-and-fro linear movement between the cylindrical housing and the piston in order to produce a stroke of the volumetric pump. This pump further comprises a bi-directional angular rotatable disc acting as a valve which connects alternately at least one inlet port and at least one outlet port to a least one pump chamber located inside the housing, and a driving mechanism arranged to dissociate at least partially the bi-directional angular movement of the rotatable disc with the to-and-fro linear movement of the housing. This driving mechanism is arranged such that the rotatable disc reaches an angular position at which it opens and/or closes the inlet and/or outlet ports when there is no relative to-and-fro linear movement between the cylindrical housing and the piston.

Abstract: A fluid pumping device having a pump housing containing a piston chamber and a reciprocating piston, an inlet port and an outlet port allowing a fluid to enter the piston chamber during an instroke of the piston and be expelled during an outstroke. The device further having a valve switching element movably mounted against a valve base member, with a piston chamber aperture connected to the piston chamber and an inlet aperture and an outlet aperture connected respectively to the inlet and outlet ports of the fluid pumping device. The element has a grooves in the valve base member providing, a first communication between the inlet aperture and the piston chamber aperture so that fluid is sucked, into the piston chamber during part of the piston instroke, and a second communication aperture expelling fluid out of the piston chamber, through the outlet port during part of the piston outstroke.

Abstract: The pump includes a housing containing a hollow elongated part, a piston arranged to move back and forth inside an elongated part, an inlet port and an outlet port arranged so that a fluid can be sucked through the inlet port into a chamber during an instroke of the piston and expelled through the outlet port during an outstroke. A linearly and/or angularly actuable valve system has a valve holder mounted on the pump housing which includes at least one through-hole extending from the piston chamber to the housing outer surface. The valve holder contains an inlet and/or outlet to alternately connect the inlet and outlet ports of the volumetric pump.

Abstract: A volumetric pump (1) comprising a piston (2) and a cylindrical chamber (3), contains an inlet port (10) and an outlet port (11). The piston (2) is actuated by a rotor (5) bearing an eccentric shaft (6). The shaft (6), being connected to the piston (2), causes the piston to slide back and forth inside the cylinder chamber (3) while having a bidirectional angular movement. The instroke of the piston (2) sucks a fluid (15) from the inlet port (10) through a first channel (12) into the pump chamber (3), the fluid being propelled through a second channel (13) to the outlet port (11) during the outstroke of the piston (2). The inlet (10) and outlet port (11) are opened and closed alternatively by the bidirectional angular movement of the piston (2) which acts as a valve for the inlet and outlet ports (10, 11).