A method of operating a pump can include advancing a stepper motor one or more additional steps in a first direction after detecting a first change in a limit sensor state corresponding to a piston reaching an end of its travel in a first direction. After advancing the stepper motor the additional step or steps in the first direction, the stepper motor can be reversed and advanced in a second direction until a second change in the limit sensor state is detected. The stepper motor can then be advanced in the second direction a predetermined number of steps associated with a full travel of the piston.

A method of operating a pump can include advancing a stepper motor one or more additional steps in a first direction after detecting a first change in a limit sensor state corresponding to a piston reaching an end of its travel in a first direction. After advancing the stepper motor the additional step or steps in the first direction, the stepper motor can be reversed and advanced in a second direction until a second change in the limit sensor state is detected. The stepper motor can then be advanced in the second direction a predetermined number of steps associated with a full travel of the piston.

The invention provides a pump for dispensing a plurality of fluids at predetermined volumes to a common location and a method of using the pump to deliver such plurality of fluids. The pump comprises one or more first syringe units, each first syringe unit comprising a first plunger and a first chamber within which the first plunger slides. A first inlet channel is fluidly connected to the first chamber of each first syringe unit and configured to receive the first fluid. The pump also comprises one or more second syringe units, each second syringe unit comprising a second plunger and a second chamber within which the second plunger slides. A second inlet channel is fluidly connected to the second chamber of each second syringe unit and configured to receive the second fluid.

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.

The invention relates to a combination metering assembly for filling liquid products into containers. The invention is characterised by a base unit (1) and pump components (3, 4, 5, 6, 11, 12, 13, 14) of at least two different pump types for a metering operation, wherein the pump components of each pump type can be combined with the base unit in order to form a pump system of the corresponding pump type, and the base unit has connection means (19, 23) for this purpose which are compatible with the connections of the pump components. The combination metering assembly can be adapted to different metering situations with little complexity and has a comparably small space requirement.

The invention relates to a combination metering assembly for filling liquid products into containers. The invention is characterised by a base unit (1) and pump components (3, 4, 5, 6, 11, 12, 13, 14) of at least two different pump types for a metering operation, wherein the pump components of each pump type can be combined with the base unit in order to form a pump system of the corresponding pump type, and the base unit has connection means (19, 23) for this purpose which are compatible with the connections of the pump components. The combination metering assembly can be adapted to different metering situations with little complexity and has a comparably small space requirement.

A pumping device includes a working chamber and a piston provided to slide in the working chamber so as to vary the useful volume of the chamber during pumping, and anti-rotation elements for the piston. Advantageously, the anti-rotation elements include an index (107) mounted radially with respect to the axis of the piston and the device includes a longitudinal slot (108), the index being provided so as to move in the slot. Advantageously, the index (107) has two approximately parallel planar faces that extend longitudinally.

A pumping device includes a working chamber and a piston provided to slide in the working chamber so as to vary the useful volume of the chamber during pumping, and anti-rotation elements for the piston. Advantageously, the anti-rotation elements include an index (107) mounted radially with respect to the axis of the piston and the device includes a longitudinal slot (108), the index being provided so as to move in the slot. Advantageously, the index (107) has two approximately parallel planar faces that extend longitudinally.

A system comprises a variable displacement pump, a metering valve, a bypass line, a pressure regulating valve, a position sensor, and a control system. At least one fuel nozzle can be in fluid communication with the output line downstream of the metering valve, wherein the variable displacement pump is configured to supply fuel to the at least one fuel nozzle. The metering valve can be disposed in the output line for controlling outlet flow from the variable displacement pump. The system can also include an actuator line parallel to the variable displacement pump and connected to the output line to provide actuation pressure from pump output of the variable displacement pump.

A system comprises a variable displacement pump, a metering valve, a bypass line, a pressure regulating valve, a position sensor, and a control system. At least one fuel nozzle can be in fluid communication with the output line downstream of the metering valve, wherein the variable displacement pump is configured to supply fuel to the at least one fuel nozzle. The metering valve can be disposed in the output line for controlling outlet flow from the variable displacement pump. The system can also include an actuator line parallel to the variable displacement pump and connected to the output line to provide actuation pressure from pump output of the variable displacement pump.