| 摘要 |
<p>A reciprocating piston with an integral valve moves in a first direction within a cylinder to pressurize viscous material contained therein, such as ice cream or the like, thereby pushing it out of a dispensing nozzle located at one end of the cylinder while simultaneously extracting viscous material from a collapsible container into the other end of the cylinder by suctioning the material from the container. When the piston moves in a second direction, the integral valve opens to allow the piston to pass through the previously suctioned viscous material then within the cylinder. The dispensing nozzle includes a normally closed, spring-biased valve opened by the force of the pressurized material, closing of the valve being assisted by a transient suction force occurring as the valved piston begins to move in the second direction through the material. Suctioning the material from the collapsible container, as opposed to compressing the container to expel the material, is preferable when the material contains entrapped gas, as is the case with ice cream, since repeated compression of such containerized material can diminish its quality.</p> |
