GEARBOX OIL RESERVOIR SHAPE OPTIMIZATION

• US 20120017722A1
• Filed: 07/26/2010
• Published: 01/26/2012
• Est. Priority Date: 07/26/2010
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Bell, Melissa A., Rollins, Michael J.
• Granted Patent: US 8,622,176 B2
• Time in Patent Office: Days
• US Class Current: 74/606.R
• CPC Class Codes: B64D 41/00 Power installations for auxiliary purposes
• CPC Class Codes: F16H 57/0452 Oil pans
• CPC Class Codes: F16H 57/0493 Gearings with spur or bevel gears differentials with spur or bevel gears F16H57/0483
• CPC Class Codes: Y10T 74/2186 Gear casings

Abstract

A gearbox for use in an auxiliary power unit has a plurality of gears received within a housing. A lube pump is mounted within the housing, and delivers oil to the plurality of gears and bearings. The lube pump has an oil supply tube for supplying oil to the pump for delivery to the plurality of gears and bearings. An oil reservoir maintains a quantity of oil above a lowermost end of the inlet tube, and is shaped such that a cross-sectional area at a lower end of the inlet tube has a first cross-sectional area. Other cross-sectional areas spaced upwardly from the first cross-sectional area are greater. A ratio of the second cross-sectional area to the first cross-sectional area is less than 3.

Claims

1. A gearbox for use in an auxiliary power unit comprising:

a plurality of gears and bearings received within a housing;

a lube pump mounted within said housing, and for delivering oil to said plurality of gears and bearings, said lube pump having an inlet tube for supplying oil to said lube pump for delivery to said plurality of gears and bearings; and

an oil reservoir for maintaining a quantity of oil above a lowermost end of said inlet tube, said oil reservoir being shaped such that a first flow cross-sectional area at a lower end of said inlet tube has a first cross-sectional area, and said oil reservoir defining a second cross-sectional area upwardly from said first cross-sectional area of a greater cross-sectional area, with a ratio of said second cross-sectional area to said first cross-sectional area being less than 3.

2. The gearbox as set forth in claim 1, wherein a ratio of said second cross-sectional area to said first cross-sectional area is between 1.5 and 2.5.

3. The gearbox as set forth in claim 2, wherein said oil reservoir has sides defined on lateral sides of a rational axis of said lube pump, said lateral sides ramping toward each other from upper locations toward said first cross-sectional area, to in part provide the difference between said first and second cross-sectional areas.

4. The gearbox as set forth in claim 3, wherein said oil reservoir having enlarged portions extending away from a nominal face of said oil reservoir, and in a direction measured along said rotational axis, with said enlarged portions ramping inwardly to a smaller portion spaced less from said nominal face at locations closer to the location of said first cross-sectional area.

5. The gearbox as set forth in claim 4, wherein a ratio of a distance from a forward face of said gearbox to a rear face of said enlarged portions relative to a distance from said forward face to the rear face of said smaller portion is between 0.8 and 0.9.

6. The gearbox as set forth in claim 5, wherein said enlarged portions on said rear face are separated by a channel.

7. The gearbox as set forth in claim 6, wherein at least one of said enlarged portions extends around to an enlarged side on a lateral side of said oil reservoir, said enlarged side being enlarged relative to a nominal side surface, and extending toward, but not reaching, said forward face.

8. The gearbox as set forth in claim 7, wherein said enlarged side extends for a distance toward said forward face, and the distance from a rear face of said enlarged portion moving to the end of said enlarged side relative to the distance from said forward face to the rear face of said enlarged portion is between 0.7 and 0.8.

9. The gearbox as set forth in claim 8, wherein a third cross-sectional area adjacent an upper end of said oil reservoir relative to said first cross-sectional area is between 0.5 and 0.6.

10. The gearbox as set forth in claim 9, wherein said lateral sides beginning ramping towards each other from an upper location defined below a lowermost end of said enlarged portion.

11. The gearbox as set forth in claim 10, wherein the shape of said oil reservoir is selected to ensure there will be a level of oil above said lowermost end of said inlet tube, and below the plurality of gears and bearings within a range of aircraft attitude limits for continuous operation and time-limited maneuvers.

12. The gearbox as set forth in claim 1, wherein said oil reservoir having enlarged portions extending away from a nominal face of said oil reservoir, and in a direction measured along said rotational axis, with said enlarged portions ramping inwardly to a smaller portion spaced less from said nominal face at locations closer to the location of said first cross-sectional area.

13. The gearbox as set forth in claim 12, wherein a ratio of a distance from a forward face of said gearbox to a rear face of said enlarged portions relative to a distance from said forward face to the rear face of said smaller portion is between 0.8 and 0.9.

14. The gearbox as set forth in claim 13, wherein said enlarged portions on said rear face are separated by a channel.

15. The gearbox as set forth in claim 14, wherein said oil reservoir has lateral sides defined on each side of a rotational axis of said lube pump, and said lateral sides ramping towards each other beginning at a location beneath a lowermost end of said enlarged portions.

16. The gearbox as set forth in claim 12, wherein at least one of said enlarged portions extends around to an enlarged side on a lateral side of said oil reservoir, said enlarged side being enlarged relative to a nominal side surface, and extending toward, but not reaching, said forward face.

19. The gearbox as set forth in claim 1, wherein the shape of said oil reservoir is selected to ensure there will be a level of oil above said lowermost end of said inlet tube, and below the plurality of gears within a range of aircraft attitude limits for continuous operation and time-limited maneuvers.

17. The gearbox as set forth in claim 17, wherein said enlarged side extends for a distance toward said forward face, and the distance from a rear face of said enlarged portion moving to the end of said enlarged side relative to the distance from said forward face to the rear face of said enlarged portion is between 0.7 and 0.8.

18. The gearbox as set forth in claim 17, wherein the shape of said oil reservoir is selected to ensure there will be a level of oil above said lowermost end of said oil supply tube, and below the plurality of gears within a range of aircraft attitude limits for continuous operation and time-limited maneuvers.