Patent ID: 7244094

Claim:
An impeller pump for a fluid, comprising: a rotary impeller having a first surface and a second surface opposing to each other, each of the first and second surfaces including a plurality of grooves arranged in a circumferential direction of the impeller and spaced from each other by a predetermined pitch; a pump casing defining a first pump channel and a second pump channel, wherein the rotary impeller is disposed within the pump casing and opposes to the first pump channel and the second pump channel, respectively; a convergence device arranged and constructed to converge the fluid discharged from the first pump channel and the fluid discharged from the second pump channel; a pulsation canceling device arranged and constructed to cancel pulsations of the fluid discharged from the first pump channel and the second pump channel, respectively; and an impact reducing device arranged and constructed to reduce impacts produced by at least one of the flow of the fluid from the first pump channel and the flow of the fluid from the second pump channel; wherein the pump casing further defines a first discharge port and a second discharge port respectively communicating with the first pump channel and the second pump channel and formed separately from each other, so that the fluid is discharged from the first and second channels via the respective first and second discharge ports and is converged at the convergence device; and wherein the pulsation canceling device is arranged and constructed to displace the first discharge port from the second discharge port by a distance corresponding to half the predetermined pitch of the grooves of the impeller, and the grooves of the impeller defined in the first surface and the grooves of the impeller disposed in the second surface are disposed at the same positions in the circumferential direction of the impeller.