Gear transfer pump with lubrication and sealing of the driveshaft and

Abstract

An improved rotary, gear within a gear transfer pump, including a pump housing having a circular pumping chamber communicating with a first port and a second port. An externally driven rotor is in meshing relationship with an internal idler gear. To enable the pump to handle an abrasive fluid medium or a non-homogenous pump fluid, an idler gear seal and a shaft seal are employed to contain pumped fluid within the pump chamber. A source of lubricating/flushing fluid is communicated to an idler gear bearing region and a shaft bearing. An idler gear seal includes a 'flow resisting' side exposed to pump chamber fluid and a 'flow passing' side exposed to lubricating/flushing fluid. The shaft seal includes a 'flow resisting' side exposed to pump chamber pressure and a 'flow-passing' side exposed to lubricating fluid. A cross-communicating fluid circuit maintains the 'flow resisting ' sides of both seals at substantially the same pressure. In an alternative embodiment, the flow resisting side of the idler gear seal and the flow resisting side of the shaft seal communicate with intake port pressure. By introducing the lubricating/flushing fluid at a pressure higher than the pressure to which the high-pressure sides of the seals are exposed, fluid leakage across the seal interfaces will occur from the 'flow passing' sides to the 'flow resisting' sides, thereby flushing the seal interfaces with the lubricating/flushing fluid. The flow of pump chamber fluid across the seal interfaces is substantially resisted.