A pump includes first and second gears coupled to one-another for rotation about respective axis. The first gear may include a concentrically disposed first hub portion and a plurality of first teeth radially projecting and circumferentially spaced about the first hub portion. A plurality of first recesses are defined by the first hub portion, communicate radially outward, and are circumferentially distributed about the first hub portion between adjacent teeth of the plurality of first teeth.

A gear pump includes a drive gear with drive gear teeth and a driven gear with driven gear teeth. The drive gear is rotatably disposed about a drive gear axis. The driven gear is rotatably disposed about a driven gear axis and is intermeshed with the drive gear such that a plurality of driven gear teeth are in sliding contact with a plurality of the driven gear teeth. One or more of the drive gear teeth or the driven gear teeth define within the tooth interior a cavity. The cavity is in fluid communication through an orifice with an inter-tooth volume defined between the contacting drive gear teeth and driven gear teeth such that fluid flows through the orifice to reduce cavitation within fluid confined within the inter-tooth volume.

A gerotor pump has a pump housing defining a chamber and having a fluid inlet and a fluid outlet. An outer gear member is supported for rotation within the chamber about a first axis, the outer gear member having a series of internal teeth. An inner gear member or inner rotor is rotatably supported within the outer gear member about a second axis spaced apart from the first axis. The inner gear member defining a series of external teeth interposed with a series of external pockets. The inner gear member defines a fluid passage therethrough to fluidly connect two nonadjacent pockets, with another pocket independent of fluid passages. The fluid passage is configured to disrupt harmonics during operation to reduce pressure ripples and associated tonal noise.

In a gear pump, an outer inner wall surface of a suction port which is located on a downstream side in a rotor rotation direction, that is, a first inner wall surface, is located inward of a bottom land between internal teeth of an outer rotor, and the suction port has a shallow portion extended inward from the first inner wall surface on the downstream side in the rotor rotation direction, and a deep portion that is formed so as to be continuous with the shallow portion and that is deeper than the shallow portion. Communication between an inter-tooth chamber and the suction port is cut off with the inter-tooth chamber facing only the shallow portion.

A fuel pump for a direct injection internal combustion engine having a housing defining a pump chamber. Driven and idler toothed gears are rotatably mounted within the pump chamber so that the driven and idler gears are in mesh with each other at a predetermined location in the pump chamber. A fluid inlet is formed through the housing and open to an inlet subchamber in the pump chamber. A fluid outlet is also formed through the housing and open to an outlet subchamber in the pump chamber. A pressure relief passageway fluidly connects the inlet subchamber to the outlet subchamber and a valve is disposed in series with the pressure relief passageway. A control circuit controls the actuation of the valve to control the pump pressure at the pump outlet.

A rotary, self-priming, positive displacement pump is described. The pump may include a pump housing including an inlet and an outlet, a pump chamber including an upper wall, a lateral wall, and a floor, first and second rotary impellers in the pump chamber, and a pair of gears each secured to the first and second rotary impellers, and a pressure relief feature operable to relieve pressure developing in a relatively high pressure zone of the pump chamber. The gears mesh with each other to ensure that the vanes do not contact one another during rotation. The pressure relief feature may comprise one or more channels formed in the pump housing and/or the first and second rotary impellers. The channels connect the high pressure zone with another zone to redistribute pressure. The channels may include one continuous channel or alternatively, a plurality of unconnected channels.

A gear having volume expansion for cavitation reduction in a gear pump mesh. The gear has a gear tooth profile; a body; a plurality of involute gear teeth extending radially outward from the body and including first and second neighboring gear teeth each having a respective tip and a root, the first and second neighboring gear teeth defining a space between them; and a root pocket formed directly into the roots of the gear teeth and in the space between the gear teeth, providing an increased gear root volume and adding trapped fluid compliance while leaving unaltered the gear tooth profile. Also disclosed is a gear pump including the gear.