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OFFSET GEARBOX FOR PTO RADIAL DRIVE SHAFT

IP.com Disclosure Number: IPCOM000248518D
Publication Date: 2016-Dec-12
Document File: 7 page(s) / 90K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention is related to gas turbine engines. Specifically, an engine having a novel accessory gearbox (AGB) and corresponding power take off (PTO) shaft arrangement is disclosed.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 42% of the total text.

OFFSET GEARBOX FOR PTO RADIAL DRIVE SHAFT

TECHNICAL FIELD

The invention is related to gas turbine engines. Specifically, an engine having a novel

accessory gearbox (AGB) and corresponding power take off (PTO) shaft arrangement is

disclosed.

BACKGROUND

Gas turbines include, but are not limited to, gas turbine power generation equipment and

gas turbine aircraft engines. A gas turbine includes a core engine having a compressor to

compress the air flow entering the core engine, a combustor in which a mixture of fuel and the

compressed air is burned to generate a propulsive gas flow, and a turbine which is rotated by the

propulsive gas flow and which is connected by a shaft to drive the compressor. A gas turbine

engine usually also includes one or more mechanically-driven accessories, such as fuel or oil

pumps, generators or alternators, control units, and the like. Such accessories are mounted to an

accessory gearbox (AGB) which extracts torque from the engine, and drives each accessory at

the required rotational speed, using an internal gear train.

In a gas turbofan engine, a quantity of air is initially compressed by a fan disposed within

an annular duct. A portion of this compressed air is ducted to the core engine and discharged

through a nozzle to provide a propulsive force. The remainder of the air compressed by the fan is

ducted around the core engine where it too is exhausted through a nozzle to provide additional

propulsive force. The ratio of the quantity of flow bypassing the core engine to that passing

through it is referred to as "bypass ratio."

A turbofan engine may be characterized as “low bypass” or “high bypass” based on the

ratio of bypass flow to core flow. Low bypass turbofan engines have been found to operate most

efficiently at supersonic velocities and are commonly used in military aircraft. The low-bypass

ratio generates the majority of the thrust through the core engine exhaust which provides higher

exhaust speed, lower drag force, and a higher power to weight ratio leading to superior

performance at supersonic speeds compared to high bypass engines.

Supersonic turbine engines with lower bypass ratio typically require mounting the AGB

on the fan case due to the limited space. The AGB is driven by a core bevel gear through a power

takeoff (PTO) shaft. Traditionally, this PTO shaft is radial, passing through the fan frame. For

many low-bypass engines, the fan frame is a vaned frame which has outlet guide vanes (OGVs)

rather than struts. To route the PTO shaft, a wide single OGV is needed. This non-conforming

OGV results in a significant loss of performance and increased noise. As such, it is desirable to

provide a low-bypass turbofan engine having an AGB and PTO shaft arrangement which does

not require modification of any OGVs.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a cross-sectional view of a prior art turbofan engine.

Fig. 2 shows a cross-sectional view of a turbofan engine according to the present

disclosure.

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