One embodiment of a modular pump includes a cover and a housing that may be engaged with one another during operation. A gearset may be positioned within an internal portion of the housing. If the modular pump is configured as a rotary pump, the gear set may be comprised of an inner gear positioned within a portion of a ring gear. The modular pump may include a spacer positioned between the cover and the housing to allow the modular pump to be configured with gear sets of varying axial dimensions.

One embodiment of a modular pump includes a cover and a housing that may be engaged with one another during operation. A gearset may be positioned within an internal portion of the housing. If the modular pump is configured as a rotary pump, the gear set may be comprised of an inner gear positioned within a portion of a ring gear. The modular pump may include a spacer positioned between the cover and the housing to allow the modular pump to be configured with gear sets of varying axial dimensions.

One embodiment of a method for operating an internal combustion engine under a pressure less than atmospheric pressure includes the steps of positioning a vacuum pump such that said vacuum pump is in fluid communication with a crankcase of said internal combustion engine, connecting a discharge of said vacuum pump to a separator, wherein a portion of said discharge of said vacuum pump condenses in said separator, connecting a vapor discharge of said separator to a filter, wherein said filter removes a portion of volatile organic compounds from said vapor discharge, and venting said filter to an ambient atmosphere.

One embodiment of a method for operating an internal combustion engine under a pressure less than atmospheric pressure includes the steps of positioning a vacuum pump such that said vacuum pump is in fluid communication with a crankcase of said internal combustion engine, connecting a discharge of said vacuum pump to a separator, wherein a portion of said discharge of said vacuum pump condenses in said separator, connecting a vapor discharge of said separator to a filter, wherein said filter removes a portion of volatile organic compounds from said vapor discharge, and venting said filter to an ambient atmosphere.

A positive displacement pump has a casing with a central body and two closing lids, the central body being provided with two cylindrical communicating chambers, one suction pipe and one discharge pipe, and two rotors revolvingly mounted in the chambers of the central body and supported by shafts revolvingly mounted in the closing lids. The two rotors include a male rotor having only protuberances, not cavities, and a female rotor having only cavities, not teeth or protuberances.

A positive displacement pump has a casing with a central body and two closing lids, the central body being provided with two cylindrical communicating chambers, one suction pipe and one discharge pipe, and two rotors revolvingly mounted in the chambers of the central body and supported by shafts revolvingly mounted in the closing lids. The two rotors include a male rotor having only protuberances, not cavities, and a female rotor having only cavities, not teeth or protuberances.

One embodiment of a pump may include an idler gear having a plurality of idler gear teeth extending radially outward, wherein at least one of the idler gear teeth may be formed with an idler gear cavity therein. The pump may include a drive gear having a plurality of drive gear teeth extending radially outward that may be intermeshed with the idler gear teeth during use. The drive gear may be formed with a recess at on axial end thereof, and the axial position of the recess may correspond to the axial position of the idler gear cavity. In one embodiment of a pump, each idler gear tooth may be formed with an identical idler gear cavity at the same relative position on each idler gear tooth.

One embodiment of a pump may include an idler gear having a plurality of idler gear teeth extending radially outward, wherein at least one of the idler gear teeth may be formed with an idler gear cavity therein. The pump may include a drive gear having a plurality of drive gear teeth extending radially outward that may be intermeshed with the idler gear teeth during use. The drive gear may be formed with a recess at on axial end thereof, and the axial position of the recess may correspond to the axial position of the idler gear cavity. In one embodiment of a pump, each idler gear tooth may be formed with an identical idler gear cavity at the same relative position on each idler gear tooth.

An external gear pump, having a driving first pump gear and a second pump gear driven by the first pump gear, which intermesh to convey a fluid from a suction side to a pressure side of the external gear pump. The first pump gear and the second pump gear each have a plurality of teeth, each having a leading tooth flank leading in the rotation direction of the corresponding pump gear and a trailing tooth flank. The leading tooth flank of the first pump gear interacts with the trailing tooth flank of the second pump gear to drive the second pump gear via the first pump gear. The trailing tooth flanks of the first pump gear extend concavely to form a fluid pocket at at least one axial position in the radial direction at least in sections in each case.

An external gear pump, having a driving first pump gear and a second pump gear driven by the first pump gear, which intermesh to convey a fluid from a suction side to a pressure side of the external gear pump. The first pump gear and the second pump gear each have a plurality of teeth, each having a leading tooth flank leading in the rotation direction of the corresponding pump gear and a trailing tooth flank. The leading tooth flank of the first pump gear interacts with the trailing tooth flank of the second pump gear to drive the second pump gear via the first pump gear. The trailing tooth flanks of the first pump gear extend concavely to form a fluid pocket at at least one axial position in the radial direction at least in sections in each case.