| abstract |
A miniaturized construction device for pressurizing a fluid, the device comprising a piston (2; 11; 17; 22; 28; 31, 33) movable in a cylinder (1), a high pressure chamber (4) located inside of the cylinder in front of the piston and a valve element (3, 13, 18, 23, 29, 37), the piston being a hollow cylindrical piston; characterized in that - the valve element is a cylindrical valve element, with one or more channels extending on the outer surface of the valve element or a cylindrical valve element being provided with a plurality of spring hooks, or having an element cylindrical valve mounted on it a coaxial plug, lowered, like a mushroom with spring hooks on it; - the cylindrical valve member being mobile without any auxiliary force between open and closed positions, said cylindrical valve element being guided by the hollow piston and being axially movable against the hollow piston; - stopping means (6; 14; 15; 19; 24; 32) are provided in the hollow piston to limit the axial movement of said cylindrical valve element; and - a defined sealing surface is provided at the inlet end of the cylindrical valve element. |