Aircraft main engine fuel pump with multiple gear stages using shared journals

摘要

A multistage gear pump assembly includes first and second gear pumps that use common shafts and are axially separated by a fixed spacer within the housing. Pressurized bearings are provided at opposite axial ends of the first and second gear pumps. The second gear pump handles cruise and idle operations of the aircraft while the first gear pump stage assists in meeting higher demand modes of engine operation. Otherwise, the first gear pump is maintained at a minimal pressure to reduce energy consumption and still provide desired stability and eliminate issues associated with bearing oil whirl associated with prior known arrangements. When additional assistance is required, such as during takeoff, climb, or windmill relight, the first gear pump advantageously contributes to the increased pressure.

主权项

1. A multistage gear pump assembly comprising:
a housing having an opening of a first dimension therein; a first gear pump received in the housing having a first drive journal shaft that rotates about a first axis and drives a first gear that operatively engages a second gear rotating about an adjacent second axis for pressurizing fluid as the first and second gears mesh with one another; a second gear pump received in the housing having a first gear received on the first drive shaft in spaced relation along the first axis from the first gear of the first gear pump, and the first gear of the second gear pump operatively engaging a second gear rotating about the second axis for pressurizing fluid as the first and second gears mesh with one another; a spacer fixed in the housing to prevent relative movement between the spacer and the housing, the spacer includes a bore having a second dimension less than the first dimension of the housing opening such that the first dimension of the housing opening cooperates with the spacer to form first and second recesses that receive the first and second gear pumps therein on opposite ends, respectively, of the spacer and the spacer is interposed between the first and second gear pumps; a first seal member interposed between the first and second gear pumps; and at least a first pressurized journal bearing supporting at least the first drive journal shaft.