Lubrication strategy for dry run pump system

Patent metadata

Field	Value
Publication number	US-10895257-B2
Application number	US-201815895046-A
Country	US
Kind code	B2
Filing date	Feb 13, 2018
Priority date	Feb 13, 2018
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

A gerotor pump assembly, and a system and method for operating a gerotor pump assembly, result in a lubrication strategy for operating in a loss-of-prime mode. An inner drive gear may be rotated in a first direction and in a second opposite direction about an axis of rotation. The inner drive gear has a number of projections extending outwardly therefrom. An outer driven gear surrounds the inner drive gear and defines a number of recessions along an inner surface configured to engage with the projections of the inner drive gear. The outer driven gear and the inner drive gear further define at least one dynamically-changing fluid cavity therebetween. The inner drive gear and the outer driven gear define an oil transfer volume clearance between a projection and a recession in a fully engaged position. Oil is maintained within the oil transfer volume clearance as the inner drive gear is rotated.

First claim

What is claimed is:

1. A gerotor pump assembly comprising:
a shaft;
an inner drive gear coupled to the shaft, the shaft and the inner drive gear being rotatable about an axis of rotation defined along a length of the shaft, the inner drive gear having a plurality of projections extending outwardly along an outer periphery thereof, the inner drive gear defining a pump running face along a side of the inner drive gear, the pump running face defining a lubrication cavity therein, the inner drive gear defining an inner aperture extending through the inner drive gear along the axis of rotation, the lubrication cavity extending within the pump running face from the inner aperture;
an outer driven gear surrounding the inner drive gear and defining a plurality of recessions along an inner surface configured to engage with the plurality of projections of the inner drive gear, the outer driven gear and the inner drive gear further defining at least one dynamically-changing fluid cavity therebetween, each projection being configured to engage with a recession of the plurality of recessions in a fully engaged position, the inner drive gear and the outer driven gear defining an oil transfer volume clearance between a projection and a recession in the fully engaged position, the outer driven gear having a bearing surface along an outer periphery thereof; and
a housing structure defining a forward inlet fluid reservoir therein and a first port connecting the forward inlet fluid reservoir to the at least one dynamically-changing fluid cavity, the housing structure further defining a forward outlet fluid reservoir therein and a second port connecting the forward outlet fluid reservoir to the dynamically-changing fluid cavity, at least a portion of the forward outlet fluid reservoir being located on an upper side of the second port, the first port being located on a lower side of the second port, the forward outlet fluid reservoir having an outlet opening defined on an upper side of the second port, the forward inlet fluid reservoir having an inlet opening defined on an upper side of the first port, the inlet opening being located on an upper side of the second port, the housing structure comprising a main body portion and a cover attached to the main body portion, the cover being disposed adjacent to the pump running face, the first and second ports being formed on a leading edge of the main body portion of the housing structure, the forward inlet fluid reservoir being formed in both the main body portion and the cover of the housing structure, the forward inlet fluid reservoir having a first side chamber symmetrically disposed about the outer driven gear, the forward outlet fluid reservoir being formed in both the main body portion and the cover of the housing structure, the forward outlet fluid reservoir having a second side chamber symmetrically disposed about the outer driven gear.

2. The gerotor pump assembly of claim 1 , further comprising:
a ball bearing arrangement having an inner race fixed to the shaft and an outer race fixed to the cover; and
a seal disposed between the shaft and the cover, a shaft cavity being defined between the shaft, the cover, the ball bearing arrangement, and the seal, the shaft cavity being configured to collect a first volume of oil.

3. The gerotor pump assembly of claim 2 , further comprising a bushing cap disposed over an end of the shaft, the gerotor pump assembly defining a hollow space between the bushing cap and the end of the shaft configured to collect a second volume of oil therein.

4. The gerotor pump assembly of claim 1 , the forward inlet fluid reservoir being in fluid communication with a filter, the inner drive gear being configured to draw fluid from a sump, through the filter, and into the forward inlet fluid reservoir.

5. The gerotor pump assembly of claim 1 , the oil transfer volume clearance being at least 500 microns wide.

6. A method of operating a gerotor pump assembly for an automotive transmission of a motor vehicle in a loss-of-prime mode, the method comprising:
rotating an inner drive gear in a first direction about an axis of rotation, the inner drive gear having a plurality of projections extending outwardly along an outer periphery thereof, an outer driven gear surrounding the inner drive gear and defining a plurality of recessions along an inner surface configured to engage with the plurality of projections of the inner drive gear, the outer driven gear and the inner drive gear further defining at least one dynamically-changing fluid cavity therebetween, each projection being configured to engage with a recession of the plurality of recessions in a fully engaged position, the inner drive gear and the outer driven gear defining an oil transfer volume clearance between a projection and a recession in the fully engaged position;
maintaining oil within the oil transfer volume clearance as the inner drive gear is rotated in the first direction;
lubricating a pump running face of the inner drive gear via a plurality of lubrication cavities defined within the pump running face, each lubrication cavity of the plurality of lubrication cavities extending within the pump running face from a central aperture of the inner drive gear, the central aperture extending along the axis of rotation;
rotating the inner drive gear in a second direction about the axis of rotation, the second direction being opposite the first direction;
maintaining oil within the oil transfer volume clearance as the inner drive gear is rotated in the second direction;
adding oil into a forward outlet fluid reservoir when the inner drive gear is rotated in the first direction;
adding oil into a forward inlet fluid reservoir when the inner drive gear is rotated in the second direction;
lubricating a bearing surface disposed along an outer periphery of the outer driven gear via at least one of a first port in fluid communication with the forward inlet fluid reservoir and a second port in fluid communication with the forward outlet fluid reservoir;
collecting oil within a shaft cavity defined between a seal, a cover, a ball bearing arrangement, and a shaft upon which the inner drive gear is mounted; and
collecting oil within a hollow space defined between the shaft and a bushing cap attached to an end of the shaft.

7. A system for providing lubrication to a gerotor pump assembly, the system comprising:
a shaft;
an inner drive gear coupled to the shaft, the shaft and the inner drive gear being rotatable about an axis of rotation defined along a length of the shaft, the inner drive gear having a plurality of projections extending outwardly along an outer periphery thereof;
an outer driven gear surrounding the inner drive gear and defining a plurality of recessions along an inner surface configured to engage with the plurality of projections of the inner drive gear, the outer driven gear and the inner drive gear further defining at least one dynamically-changing fluid cavity therebetween, each projection being configured to engage with a recession of the plurality of recessions in a fully engaged position, the inner drive gear and the outer driven gear defining an oil transfer volume clearance between a projection and a recession in the fully engaged position,

wherein the inner drive gear is configured to be rotated in a first direction about the axis of rotation and a second direction about the axis of rotation, the first direction being opposite the second direction, the inner drive gear and the outer driven gear being configured to maintain oil within the oil transfer volume clearance as the inner drive gear is rotated in the first direction and in the second direction; and
a housing structure defining a forward inlet fluid reservoir therein and a first port

Assignees

• Gm Global Tech Operations Llc

Inventors

• Parrish Robert
• Fannin Michael P
• Selever Ted T

Classifications

• F04C15/0038

  Shaft sealings specially adapted for rotary-piston machines or pumps · CPC title

• F04C15/0003

  Sealing arrangements in rotary-piston machines or pumps (sealing in general F16J) · CPC title

• F04C15/0088

  Lubrication (of machines or engines in general F01M) · CPC title

• F04C2240/30

  Casings or housings · CPC title

• F04C2240/809

  Lubricant sump · CPC title