| 摘要 |
A valveless dosing pump is disclosed which comprises a housing having a cylindrical bore therein with a plurality of hard material rings press-fit into the bore and spaced from each other to leave annular inlet and outlet spaces. First and second pistons are slidably mounted within the rings and the housing is provided with inlet and outlet conduits communicating with the inlet and outlet spaces. The first piston is connected to a drive unit which moves the first piston through a complete stroke between the inlet and outlet spaces. The driving unit also abuts the second piston which moves through part of the stroke of the first piston and in the same direction. The difference between the strokes of the first and second pistons comprise a dosing volume. The rings are made of a suitable low friction dense and hard wear-resistant material, such as, silicon carbide or silicon nitride. |
