Abstract: A rotary vane pump has an open ended pump cylinder mounting a drive motor at one end and a ported end plate and sound chamber at the other end. The cylinder contains a rotor mounted to an eccentric drive shaft and having vane grooves receiving slidable vanes contacting an inner diameter of the cylinder. The end plate has an outlet port and primary and secondary inlet ports in communication with the cylinder interior, the inlet ports being in communication with an area of net expansion. The sound chamber has an intake port and an exhaust port in communication with the respective outlet and primary and secondary inlet ports of the end plate. The sound chamber is partitioned to define a number of internal cavities through which the incoming air is routed to the secondary inlet port.

Abstract: A rotary vane pump has an open ended pump cylinder mounting a drive motor at one end and a ported end plate and sound chamber at the other end. The cylinder contains a rotor mounted to an eccentric drive shaft and having vane grooves receiving slidable vanes contacting an inner diameter of the cylinder. The end plate has an outlet port and primary and secondary inlet ports in communication with the cylinder interior, the inlet ports being in communication with an area of net expansion. The sound chamber has an intake port and an exhaust port in communication with the respective outlet and primary and secondary inlet ports of the end plate. The sound chamber is partitioned to define a number of internal cavities through which the incoming air is routed to the secondary inlet port.