| 摘要 |
A main piston (6) and a precursor piston (8) are arranged in a cylindrical dosing tube (5) which opens into a dispensing region (9). In the initial position, a chamber (4) is formed between the main piston (6) and the precursor piston (8). By the simultaneous advance of the two pistons (6, 8), the dose is moved into the dispensing region (9). After the solid material has fallen out, the precursor piston (8) is first of all moved back until it rests against the main piston (6). After this, both pistons are first of all moved back simultaneously until the precursor piston (8) has reached its initial position. When the main piston (6) is then moved back into its initial position, the chamber (4) is reformed. Any change in the dose is made by changing the spacing between the main piston (6) and the precursor piston (8). Solids are prevented from sticking in the delivery chamber (4) by rotation of the precursor piston (8). Since the filling region (1) is separated from the dispensing region (9) during the entire operation, different pressures and humidities may prevail in the two regions. <IMAGE>
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