Pump for highly viscous and pasty material - has control piston loaded with pressurised material for reducing spring force

摘要

The valveless metering pump is used esp. for thick or pasty materials. The pump chamber has inlet and outlet openings bounded by sliding piston and by control piston in line with the pumping piston. The control piston covers the outlet opening in control piston initial position. Pump may be used also with high pressures and may have large cross-section without need for increasing the strength of control piston spring. When pump is used as high pressure pump, then control piston (3) can be pressurised on its rear face parallel to the spring (12) resting against the housing (1). The control piston (3) is loaded on its rear face by the material to be pumped. The chamber (31) behind the control piston (3) is connected to the pump outlet (5) for this purpose.