Gear, a method of manufacturing a gear and a geared gas turbine engine

Patent metadata

Field	Value
Publication number	US-10744566-B2
Application number	US-201815951209-A
Country	US
Kind code	B2
Filing date	Apr 12, 2018
Priority date	Apr 13, 2017
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

A gas turbine engine comprises a gearbox comprising a sun gear, an annulus gear, a plurality of planet gears and a carrier. The sun gear meshes with the planet gears and the planet gears mesh with the annulus gear. A planet gear comprises a first annular structure, a plurality of teeth extending radially from the first annular structure and a second annular structure abutting and secured to a cylindrical surface of the first annular structure. The first annular structure and the teeth consist of steel, the second annular structure comprises a metal matrix composite, the metal matrix comprising aluminium, aluminium alloy, steel, titanium or titanium alloy, the reinforcing material comprising titanium diboride, titanium carbide or titanium nitride. The second annular structure reduces the mass but maintains, or increases, the stiffness of the planet gear to carry centrifugal loads and to maintain roundness of the planet gears.

First claim

The invention claimed is:

1. A gear comprising a first annular structure and a second annular structure,
a plurality of teeth extending radially from the first annular structure, the first annular structure having a cylindrical surface, the first annular structure and the teeth consisting of steel,
the second annular structure abutting and being secured to the cylindrical surface of the first annular structure, the second annular structure comprising a metal matrix composite, the metal matrix composite comprising a metal matrix and reinforcing material, the metal matrix is selected from the group consisting of aluminium, aluminium alloy, steel, titanium and titanium alloy, the reinforcing material comprising a ceramic material, the reinforcing material comprises one or more of alumina, boron, boron carbide, boron nitride, carbon, silicon carbide, silicon nitride, titanium carbide, titanium diboride, titanium nitride and tungsten carbide,
the first annular structure, the teeth and the second annular structure are a unitary monolithic structure.

2. A gear as claimed in claim 1 , wherein the reinforcing material comprises particles.

3. A gear as claimed in claim 1 , wherein the reinforcing material comprises fibres.

4. A gear as claimed in claim 1 , wherein the cylindrical surface is a radially inner surface, the teeth extend radially outwardly from the first annular structure and the second annular structure is arranged radially within the first annular structure.

5. A planet gear comprising a first annular structure, a second annular structure and a third annular structure,
a plurality of teeth extending radially outwardly from the first annular structure, the first annular structure having a cylindrical inner surface, the first annular structure and the teeth consisting of steel,
the second annular structure being arranged radially within and being secured to the cylindrical inner surface of the first annular structure, the second annular structure comprising a metal matrix composite, the metal matrix composite comprising a metal matrix and reinforcing material,
the third annular structure being arranged radially within and being secured to the second annular structure, the third annular structure comprises steel,
wherein the first annular structure, the teeth, the second annular structure, and the third annular structure are a unitary monolithic structure.

6. A planet gear as claimed in claim 5 wherein the steel is gear steel.

7. A planet gear as claimed in claim 5 wherein the first annular structure, the teeth, the second annular structure and the third annular structure are a unitary monolithic structure.

8. A planet gear as claimed in claim 5 wherein the metal matrix is selected from the group consisting of aluminium, aluminium alloy, steel, titanium and titanium alloy, the reinforcing material comprising a ceramic material, the reinforcing material comprises one or more of alumina, boron, boron carbide, boron nitride, carbon, silicon carbide, silicon nitride, titanium carbide, titanium diboride, titanium nitride and tungsten carbide.

9. A gear as claimed in claim 5 , wherein the reinforcing material comprises particles.

10. A gear as claimed in claim 5 , wherein the reinforcing material comprises fibres.

11. A gas turbine engine comprising a gearbox, the gearbox comprising a sun gear, an annulus gear, a plurality of planet gears and a planet gear carrier, the planet gears being rotatably mounted in the planet gear carrier, the sun gear meshing with the planet gears and the planet gears meshing with the annulus gear, wherein one or more of the sun gear, the annulus gear and a planet gear comprising a first annular structure and a second annular structure, a plurality of teeth extending radially from the first annular structure, the first annular structure having a cylindrical surface, the second annular structure abutting and being secured to the cylindrical surface of the first annular structure, wherein the first annular structure, the teeth, and the second annular structure comprising a unitary monolithic structure, the first annular structure and the teeth consisting of steel, the second annular structure comprising a metal matrix composite, the metal matrix composite comprising a metal matrix and reinforcing material.

12. A gas turbine engine as claimed in claim 11 wherein the metal matrix is selected from the group consisting of aluminium, aluminium alloy, steel, titanium and titanium alloy, the reinforcing material comprising a ceramic material, the reinforcing material comprises one or more of alumina, boron, boron carbide, boron nitride, carbon, silicon carbide, silicon nitride, titanium carbide, titanium diboride, titanium nitride and tungsten carbide.

13. A gas turbine engine as claimed in claim 11 wherein at least the annulus gear comprises a first annular structure and a second annular structure, a plurality of teeth extending radially from the first annular structure, the first annular structure having a cylindrical surface, the second annular structure abutting and being secured to the cylindrical surface of the first annular structure, wherein the first annular structure, the teeth, and the second annular structure comprising a unitary monolithic structure, the first annular structure and the teeth consisting of steel, the second annular structure comprising a metal matrix composite, the metal matrix composite comprising a metal matrix and reinforcing material.

14. A gas turbine engine as claimed in claim 11 wherein at least the annulus gear and all of the planet gears each comprises a first annular structure and a second annular structure, a plurality of teeth extending radially from the first annular structure, the first annular structure having a cylindrical surface, the second annular structure abutting and being secured to the cylindrical surface of the first annular structure, wherein the first annular structure, the teeth, and the second annular structure comprising a unitary monolithic structure, the first annular structure and the teeth consisting of steel, the second annular structure comprising a metal matrix composite, the metal matrix composite comprising a metal matrix and reinforcing material.

Assignees

• Rolls Royce Plc

Inventors

• Clarke Derek W J

Classifications

• F16H55/06 Primary

  Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties · CPC title

• B22F5/08 Primary

  of toothed articles, e.g. gear wheels; of cam discs · CPC title

• B33Y70/10

  Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials · CPC title

• Y02P10/25

  Process efficiency · CPC title

• F16H55/17 Primary

  Toothed wheels (worm wheels F16H55/22; chain wheels F16H55/30) · CPC title