Patent ID: 8291933

Claim:
A handpiece comprising: a body defining a chamber with upstream and downstream portions and a first flow path between the upstream and downstream chamber portions; an inlet port of the body coupled to the upstream chamber portion; a pulse engine coupled to the downstream chamber portion; an outlet port of the body coupled to the pulse engine; and a spring-less flow control member movable between open and closed positions between the upstream and downstream chamber portions, wherein the first flow path is configured to flow around the flow control member when the flow control member is in the open position; wherein the body further defines a second flow path between the downstream chamber portion and the flow control member which is less restrictive than the first flow path and further wherein, in the closed position, flow from the inlet port tends to move the member to the open position thereby allowing flow through the first flow path, and in the open position, a pressure increase from the pulse engine traveling along the second flow path tends to move the flow control member to the closed position before fluid back flows through the first flow path and around the flow control member; wherein the second flow path has a greater diameter than the first flow path throughout a region of the second flow path between the flow control member and a junction of the first flow path and the second flow path.