GEARBOX RATIO CHANGE

• US 20200131924A1
• Filed: 10/24/2018
• Published: 04/30/2020
• Est. Priority Date: 10/24/2018
• 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: Fox, Paul F.
• Granted Patent: US 11,168,577 B2
• Time in Patent Office: Days
• CPC Class Codes: F01D 15/08 Adaptations for driving, or combinations with, pumps
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F01D 15/12 Combinations with mechanical gearing driven by multiple engines F01D13/00
• CPC Class Codes: F02C 7/32 Arrangement, mounting, or driving, of auxiliaries
• CPC Class Codes: F05D 2230/80 Repairing, retrofitting or upgrading methods
• CPC Class Codes: F05D 2260/4031 as in toothed gearing
• CPC Class Codes: F16H 1/206 characterised by the driving or driven member being composed of two or more gear wheels
• CPC Class Codes: F16H 37/04 Combinations of toothed gearings only F16H37/06 takes precedence
• CPC Class Codes: F16H 57/02 Gearboxes; Mounting gearing therein
• CPC Class Codes: F16H 57/023 Mounting or installation of gears or shafts in the gearboxes, e.g. methods or means for assembly
• CPC Class Codes: F16H 61/22 Locking of the control input devices constructional features of locking or disabling mechanisms F16H63/34

Abstract

A method of modifying an existing gearbox wherein the existing gearbox has an input shaft connected to drive a first idler gear. The first idler gear engages a gear for driving a fuel pump at a first speed. There is a first distance between a center point of the first idler gear and the fuel pump gear. The step includes replacing the first idler gear with a replacement first idler gear having a distinct number of teeth, and replacing the fuel pump gear with a replacement fuel pump gear having a distinct number of teeth such that a speed output to the fuel pump is distinct from the speed at the fuel pump with the existing gearbox. A gearbox is also disclosed.

Claims

1. A method of modifying an existing gearbox comprising the steps of:

(a) wherein the existing gearbox has an input shaft connected to drive a first idler gear, the first idler gear engages a first fuel pump gear for driving a fuel pump at a first speed, and there being a first distance between a center point of the first idler gear and the fuel pump gear; and

(b) including the step of replacing said first idler gear with a replacement first idler gear having a distinct number of teeth, and replacing said first fuel pump gear with a replacement fuel pump gear having a distinct number of teeth such that a speed output to said fuel pump is distinct from the first speed.

2. The method as set forth in claim 1, wherein the method further includes the step of inserting a second idler gear rotating with said replacement fuel pump gear, and selectively engaging a drive gear for a generator and said second idler gear driving said replacement fuel pump gear.

3. The method as set forth in claim 2, wherein said replacement first idler gear has 77 teeth.

4. The method as set forth in claim 3, wherein said second idler gear has 24 teeth.

5. The method as set forth in claim 4, wherein said replacement fuel pump drive gear has 122 teeth.

6. The method as set forth in claim 3, wherein said replacement fuel pump drive gear has 122 teeth.

7. The method as set forth in claim 2, wherein said replacement fuel pump drive gear has 122 teeth.

8. The method as set forth in claim 4, wherein said replacement fuel pump drive gear has 95 teeth.

9. The method as set forth in claim 3, wherein said replacement fuel pump drive gear has 95 teeth.

10. The method as set forth in claim 3, wherein said replacement fuel pump gear and a gear driving said replacement fuel pump gear have diameters derived using a non-standard pitch.

11. The method as set forth in claim 2, wherein said replacement fuel pump drive gear has a 95 teeth.

12. The method as set forth in claim 2, wherein said replacement fuel pump gear and a gear driving said replacement fuel pump gear have diameters derived using a non-standard pitch.

13. The method as set forth in claim 2, wherein a supplemental gearbox is mounted to an existing gearbox and houses a portion of said drive gear for said generator, said second idler gear, and said replacement fuel pump gear.

14. The method as set forth in claim 1, wherein said replacement fuel pump gear has 72 teeth.

15. The method as set forth in claim 14, wherein said replacement fuel pump gear and a gear driving said replacement fuel pump gear have diameters derived using a non-standard pitch.

16. The method as set forth in claim 1, wherein said replacement fuel pump gear and a gear driving said replacement fuel pump gear have diameters derived using a non-standard pitch.

17. A gearbox for driving a plurality of components associated with a gas turbine engine comprising;

a first idler gear selectively engaged to be driven by an input, wherein said first idler gear drives a fuel pump drive gear at a first speed, wherein a ratio of a diameter of said fuel pump drive gear to a number of teeth on said fuel pump drive gear is not equal to a ratio of a diameter of a gear driving said fuel pump drive gear to a number of teeth on said gear driving said fuel pump drive gear.

18. The gearbox as set forth in claim 19, wherein said first idler gear has 77 teeth and said fuel pump drive gear has 72 teeth.

19. The gearbox as set forth in claim 17, wherein a second idler gear is selectively driven and is said gear driving said fuel pump drive gear, said second idler gear has 24 teeth, and said fuel pump gear has 95 teeth or 122 teeth, said fuel pump gear has 122 teeth.

20. The gearbox as set forth in claim 17, wherein said first idler gear is mounted in a first gearbox, and said first idler gear rotating on an axis, and there being a supplemental gearbox spaced from said first gearbox along said axis of rotation, with said second idler gear and said fuel pump drive gear being mounted in said supplemental gearbox.