Patent ID: 7045061

Claim:
A dialysis device comprising: a solution supply chamber for supplying a new dialysis solution to a dialyser via a supply passage; a solution collection chamber for collecting a used dialysis solution from the dialyser via a collection passage; a water supply passage for supplying clean water to said solution supply chamber; a waste solution passage for discharging the used dialysis solution from said solution collection chamber; and a piston pump that moves a piston up and down in a cylinder to feed a solution, wherein said dialysis device further comprises: a washing passage that provides communication between said water supply passage and said waste solution passage to flow said clean water therethrough; and an open/close valve for opening and closing said washing passage, and said piston pump is at least one of a concentrate solution pump that sucks a dialysis concentrate solution from a concentrate solution supply source and supplies the sucked dialysis concentrate solution to said solution supply chamber, and an extraction pump that sucks the used dialysis solution from said collection passage and discharges the sucked used dialysis solution to said waste solution passage, the cylinder of said piston pump has an inflow port for flowing a solution into a gap between an inner surface of the cylinder and an outer surface of the piston, and an outflow port for flowing the solution out of the gap, and the inflow port and the outflow port are connected in the way of said washing passage, and said open/close valve is intermittently opened during a dialysis operation to flow the clean water in the water supply passage through the gap between the inner surface of the cylinder and the outer surface of the piston.