| CPC F04C 15/0026 (2013.01) [F01C 21/02 (2013.01); F04C 2/086 (2013.01); F04C 2/18 (2013.01); F04C 15/0042 (2013.01); F16C 17/107 (2013.01); F04C 2240/56 (2013.01); F16C 2360/00 (2013.01)] | 12 Claims |
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1. A gear stage of a pump comprising:
a housing defining a gear chamber, the housing defining an inlet and an outlet in fluid communication with the gear chamber;
a gear arrangement disposed within the gear chamber configured to drive fluid from the inlet to the outlet, the gear arrangement including at least a gear rotatable about an axis of rotation;
a journal coupled to the gear, the journal extending along the axis of rotation and being configured to drive rotation of the gear about the axis of rotation;
a fixed bearing at a first axial side of the gear for radially supporting the journal relative to the housing such that the journal is rotatable about the axis of rotation relative to the housing; and
an axially-movable bearing at an opposite second axial side of the gear for radially supporting the journal relative to the housing such that the journal is rotatable about the axis of rotation relative to the housing, the axially-movable bearing defining a through-bore for receiving the journal, the through-bore extending between a first axial end and a second axial end of the axially-movable bearing, the first axial end facing the second axial side of the gear and the second axial end facing away from the gear, the axially-movable bearing being axially movable along the axis of rotation within the journal toward and away from the gear, the axially-movable bearing being rotationally fixed relative to the housing, the through-bore being in fluid pressure communication with inlet pressure corresponding to the inlet of the housing, and wherein the discharge pressure corresponding to the outlet of the housing acts on the second axial end of the axially-movable bearing to cause the first axial end of the axially-movable bearing to bear axially against the second axial side of the gear;
wherein:
a. the first axial end of the axially-movable bearing defines an axial end face configured to contact the second axial side of the gear, the axial end face extending radially outwardly from the through-bore toward an outer circumference of the axial end face, the axial end face defining a first circumferential groove, the first circumferential groove dividing the axial end face into an inner region extending radially between the first circumferential groove and the through-bore and an outer region extending radially between the first circumferential groove and the outer circumference, the outer region being exposed to the discharge pressure, the first circumferential groove being in fluid communication with the discharge pressure such that a pressure gradient radially across the outer region is minimized, the inner region having a pressure differential between the discharge pressure at the first circumferential groove and the inlet pressure at the through-bore; and
b. the axially-movable bearing includes an outer circumferential portion defining an outer circumferential boundary that extends axially between the first and second axial ends of the axially-movable bearing, the outer circumferential portion including an outer land for supporting the journal radially relative to the housing, the outer land having a first dimension that extends circumferentially about the axis of rotation and a second dimension that extends axially along the axis of rotation, the outer circumferential portion defining a drum portion disposed axially between the outer land and the second axial end of the axially-movable bearing, the drum portion being exposed to the discharge pressure, the second dimension of the outer land extending between the drum portion and an inlet pressure region adjacent the first axial end of the axially-movable bearing, the outer land defining a second circumferential groove extending circumferentially along the outer land to divide the outer land into a first axial region adjacent the drum portion and a second axial region adjacent the inlet pressure region, the second circumferential groove being in direct fluid communication with from the drum portion to minimize a pressure gradient across the first axial region, the second axial region having a pressure differential between the discharge pressure at the second circumferential groove and the inlet pressure at the inlet pressure region; and
wherein the first and second circumferential grooves each extend over less than a full circumference of the axially-movable bearing, and wherein the first and second circumferential grooves are circumferentially offset from one another and positioned on opposite sides of the axis of rotation.
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