Patent ID: 6957798

Claim:
A pinch valve comprising: a housing that encloses a flexible tube; a first pinch element and a second pinch element, each being oriented on a respective axis of rotation transverse to an axis of extension of the tube, each of the first pinch element and the second pinch element being constructed and arranged to rotate with respect to each other between a fully closed and a fully open position; and wherein each pinch element respectively defines a pinch region that confronts an outer wall of the tube to define a profile that surrounds substantially the outer perimeter of the tube, the pinch region varying about a circumference of each of the first pinch element and the second pinch element between (a) the fully open position in which the profile conforms to a shape of an outer perimeter of the tube in an unpinched state, through (b) a continuous ramping surface in which the profile at various points around the circumference defines, for pinching the tube, progressively from a shortened flattened segment at large depth with respect to the axis of extension and large-radius filleted ends to a lengthened flattened segment of small depth with respect to the axis of extension and small-radius filleted ends to (c) the fully closed, position in which the profile defines, a maximum length flattened segment at minimum depth with respect to the axis of extension and minimum-radius filleted ends, whereby the tube is substantially engaged along substantially the outer perimeter by the pinch region at all circumferential positions of the pinch elements.