Pneumatic pinch mechanism for a deformable tube

摘要

A pinch mechanism, which can be used as part of a pump, includes a deformable tube ( 10 ) enclosed within a body ( 11 ) which has a first chamber ( 11 a). The deformable tube ( 10 ) defines a flow passage. A second chamber ( 19 ) is coupled via passage ( 17 ) to the first chamber ( 11 a). A piston ( 20 ) is located within the second chamber ( 19 ) and movable between first and second positions. Upon moving to the first position a pressure increase occurs in the first chamber ( 11 a). Upon moving to the second position a negative pressure is created in the first chamber ( 11 a). A vent means ( 25 ) is located at a point during movement of the piston ( 20 ) between the first and second positions which enables pressure equalisation within the second chamber ( 19 ) to occur.