| 摘要 |
The invention relates to a device for dosing or for pumping in a controlled manner a liquid or slurry, a device having a piston freely reciprocating in a cylinder; members connected to the cylinder on the opposite sides of the path of the piston movement for feeding the liquid or slurry under pressure into the cylinder in order to move the piston or for discharging liquid or slurry from the cylinder by means of the pressure of the liquid or slurry directed into the cylinder to the opposite side of the piston, when the piston returns; a valve member in the feed and discharge members of the liquid or slurry for their alternate opening and closing; switches fitted at the ends of the cylinder for sensing the position of the piston; and a control unit for controlling the stroke frequency of the piston, and thereby the volume flow of the liquid or slurry, and for transmitting the signal given by the switch to the valve member in order to open and close it at different positions of the piston. According to the invention, the control unit has been fitted to adjust the time interval between the starts of the piston movement. Thus the stroke frequency of the piston and the volume flow of the liquid or slurry remain constant in spite of variations in the feed pressure and viscosity of the liquid or slurry. |
