Variable-speed gear box with hydraulic system for tiltrotor aircraft

Patent metadata

Field	Value
Publication number	US-11022213-B2
Application number	US-201816105116-A
Country	US
Kind code	B2
Filing date	Aug 20, 2018
Priority date	Aug 20, 2018
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

An aircraft includes a variable-speed gearbox. The variable-speed gearbox includes a low-speed gear train and a high-speed gear train, each gear train of which is configured to selectively provide torque from an engine of the aircraft to a proprotor. The variable-speed gearbox also includes a hydraulic system configured to provide torque to the proprotor. The hydraulic system includes a hydraulic pump driven by the engine of the tiltrotor aircraft and a variable-displacement motor driven by a hydraulic fluid from the hydraulic pump.

First claim

What is claimed is:

1. A variable-speed gearbox for an aircraft, the variable-speed gearbox comprising:
a low-speed gear train and a high-speed gear train, each of which is configured to selectively provide torque from an engine of the aircraft to a proprotor;
a hydraulic system configured to provide torque to the proprotor;
a hydraulic pump driven by the engine of the aircraft;
a variable-displacement motor driven by a hydraulic fluid from the hydraulic pump;
a hydraulic pump gear train that meshes with at least one of the high-speed and low-speed gear trains and is coupled to the hydraulic pump; and
a variable-displacement motor gear train that meshes with the hydraulic pump gear train and is coupled to an output shaft of the variable-displacement motor.

2. The variable-speed gearbox of claim 1 , wherein the low-speed gear train comprises a sprag clutch coupled between the low-speed gear train and the engine of the aircraft.

3. The variable-speed gearbox of claim 1 , wherein the high-speed gear train comprises a sprag clutch coupled between the high-speed gear train and the engine of the aircraft.

4. The variable-speed gearbox of claim 1 , wherein the hydraulic system comprises a bypass valve coupled between the hydraulic pump and the variable-displacement motor and configured to allow hydraulic fluid to bypass the variable-displacement motor.

5. The variable-speed gearbox of claim 1 , wherein the variable-displacement motor gear train comprises a sprag clutch coupled to the variable-displacement motor.

6. The variable-speed gearbox of claim 1 , wherein the hydraulic system further comprises:
a heat exchanger coupled between the variable-displacement motor and the hydraulic pump; and
a hydraulic fluid reservoir coupled between the variable-displacement motor and the hydraulic pump.

7. A tiltrotor aircraft comprising:
a first and a second variable-speed gearbox, each gearbox comprising:
a low-speed gear train and a high-speed gear train, each of which is configured to selectively provide torque from an engine of the tiltrotor aircraft to a proprotor;
a hydraulic system configured to provide torque to the proprotor, the hydraulic system comprising a hydraulic pump driven by the engine of the tiltrotor aircraft and a variable-displacement motor driven by a hydraulic fluid from the hydraulic pump;
a hydraulic pump gear train that meshes with at least one of the high-speed and low-speed gear trains and is coupled to the hydraulic pump; and
a variable-displacement motor gear train that meshes with the hydraulic pump gear train and is coupled to an output shaft of the variable-displacement motor.

8. The tiltrotor aircraft of claim 7 , wherein the low-speed gear train comprises a sprag clutch coupled between the low-speed gear train and the engine of the tiltrotor aircraft.

9. The tiltrotor aircraft of claim 7 , wherein the high-speed gear train comprises a sprag clutch coupled between the high-speed gear train and the engine of the tiltrotor aircraft.

10. The tiltrotor aircraft of claim 7 , wherein a variable-displacement motor gear train coupled to the variable-displacement motor comprises a sprag clutch coupled to the variable-displacement motor.

11. The tiltrotor aircraft of claim 7 , wherein the hydraulic system comprises a bypass valve coupled between the hydraulic pump and the variable-displacement motor and configured to allow hydraulic fluid to bypass the variable-displacement motor.

Assignees

• Bell Helicopter Textron Inc

Inventors

• Fenny Carlos Alexander
• Stamps Frank

Classifications

• B64C29/0033 Primary

  the propellers being tiltable relative to the fuselage · CPC title

• F16H3/083

  with radially acting and axially controlled clutching members, e.g. sliding keys · CPC title

• B64D35/04

  characterised by the transmission driving a plurality of propellers or rotors · CPC title

• F16H3/097

  the input and output shafts being aligned on the same axis · CPC title

• F16H47/02

  the fluid gearing being of the volumetric type · CPC title