Patent ID: 12227284

DETAILED DESCRIPTION

Additional features, advantages, and embodiments of the present disclosure are set forth or apparent from a consideration of the following detailed description, drawings, and claims. Moreover, both the foregoing summary of the present disclosure and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the disclosure as claimed.

Various embodiments of the present disclosure are discussed in detail below. While specific embodiments are discussed, this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and the scope of the present disclosure.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value.

As used herein, the terms “axial” and “axially” refer to directions and orientations that extend substantially parallel to a centerline of the aircraft engine or the combustor. Moreover, the terms “radial” and “radially” refer to directions and orientations that extend substantially perpendicular to the centerline of the aircraft engine or a fuel-air mixer assembly.

A pitch change mechanism can be used to change the pitch of a blade of an aircraft. Pitch change orients the blade relative to incoming airflow. When an aircraft is stationary with the propeller spinning (in relatively calm air), the airflow vector for each blade is mainly from a side of the blade (feather position). However, as the aircraft starts to move forward, the relative airflow vector increasingly faces a front edge of the blade. To maintain an angle of attack of the blade relative to the airflow, the pitch of the blade is adjusted towards a fine position.

The first propeller engines were provided with propeller blades having a fixed pitch. These propeller engines were not, however, efficient over a range of flight conditions. For example, if the angle of the propeller blade is set for takeoff and climb performance, the propeller engine will be inefficient in cruising flight, because the propeller blade will have a low angle of attack. On the other hand, if the angle of the propeller blade is set for cruise performance, the propeller engine may stall at lower speeds, because the propeller blade will have too high of an angle of attack. Therefore, a propeller engine with an adjustable propeller blade angle is more efficient over a range of conditions for operating the aircraft engine. A propeller engine provided with propeller blades having a variable pitch can have a nearly constant efficiency over a range of airspeed.

The present mechanism for changing the pitch of a blade uses a combination of pitch change mechanism functional features controlled by an integrated system and can be accomplished by a hydraulic dual channel axial actuator, an electrically driven auxiliary feathering pump, an oil transfer bearing, and one or more oil channels, as will be described further in detail in the following paragraphs. This arrangement eliminates counterweights and reduces weight and, thus, increases fuel efficiency.

The axial actuator is configured to rotate with the propeller shaft and includes an axially movable cylinder connected to blades via linkage yokes. The axial movement of the actuator cylinder is transferred to a change in the pitch angle of the blades. Oil is supplied the actuator at a pressure through an oil transfer bearing with the engine oil in a normal operating mode, or by an auxiliary hydraulic pump electrically driven with a separate auxiliary oil reservoir in the event of an engine oil pressure drop. The auxiliary oil reservoir can be located, for example, in a space inside a main engine oil tank, as a tank inside a tank configuration. A pitch lock function is accomplished by a hydraulic system or a mechanical lock controlled by the system.

FIG.1is a cross-sectional of a pitch change mechanism101of an aircraft engine100for changing the pitch of a plurality of blades of the aircraft engine100, according to an embodiment of the present disclosure. The term “aircraft engine” is used herein to include, but is not limited to, an open fan engine, an unducted fan engine, or any engine having blades outside a nacelle of the aircraft engine, a propeller engine, or a turboprop engine, etc.FIG.1shows a pitch change mechanism101of the aircraft engine100. The aircraft engine100includes a plurality of blades102. The plurality of blades102are coupled to the pitch change mechanism101. The plurality of blades102extend radially from the pitch change mechanism101. The pitch change mechanism101has a plurality of crankshafts104. The plurality of crankshafts104are configured to receive the plurality of blades102. Each of the plurality of blades102is linked to a corresponding one of the plurality of crankshafts104. Each crankshaft104is configured to rotate around its longitudinal axis104A, which generally corresponds to a longitudinal axis of the propeller blade102. The pitch change mechanism101further includes a unison ring106. Each of the plurality of crankshafts104is coupled to the unison ring106by a corresponding linkage yoke in a plurality of linkage yokes108.

The pitch change mechanism101also includes an inner shaft110. The unison ring106is coupled to the inner shaft110. For example, in an embodiment, the unison ring106is coupled to the inner shaft110by a plurality of fasteners110A. The inner shaft110is thus coupled to the plurality of crankshafts104.

The pitch change mechanism101includes an actuator cylinder112and an actuator piston114. A diameter of the actuator cylinder112is greater than a diameter of the actuator piston114. The actuator cylinder112is coupled to the inner shaft110. The actuator cylinder112is configured to move relative to the actuator piston114along a longitudinal axis101A of the pitch change mechanism101. In an embodiment, the actuator piston114is fixed in the longitudinal direction. The pitch change mechanism101also includes an actuator cylinder support116configured to support the actuator cylinder112. The actuator cylinder support116is coupled to the actuator piston114. The actuator cylinder support116contacts the actuator cylinder112via a plurality of sealing joints112A at different points along the longitudinal axis101A of the pitch change mechanism101. In addition, the actuator cylinder support116further contacts the actuator piston114. The sealing joints112A are coupled to the actuator cylinder support116and are immovable when the actuator cylinder112moves relative to the actuator piston114. In an embodiment, a sealing joint112B is movable with the actuator cylinder112on a surface of the actuator piston114relative to the actuator piston114. A back end of the actuator cylinder support116contacts a front end of actuator piston114. A diameter of the actuator cylinder support116is greater than a diameter of the actuator piston114. The actuator piston114has a cylinder portion114A provided at a front end and a conical portion114B provided at a back end. The cylinder portion114A defines a chamber114C of the actuator piston114. In an embodiment, the sealing joint112B moves with the actuator cylinder112on a surface of the cylinder portion114A of the actuator piston114.

The inner shaft110has a conical shape or a funnel-like shape that extends within a chamber116A (“coarse chamber”) defined by the actuator cylinder support116. The inner shaft110has a conical portion110B and a cylindrical portion110C connected to the conical portion110B. The actuator cylinder112is connected to the conical portion110B of the inner shaft110. The conical portion110B extends radially to connect with the unison ring106. The cylindrical portion110C is configured to be enclosed within the chamber116A defined by the actuator cylinder support116of the actuator cylinder112.

The pitch change mechanism101also includes a mechanical pitch lock118. The mechanical pitch lock118is provided within the chamber116A of the actuator cylinder support116. The mechanical pitch lock118includes an annular pitch lock member118A that surrounds the cylindrical portion110C of the inner shaft110.

The pitch change mechanism101also includes an oil transfer bearing120. The oil transfer bearing120is provided within the chamber114C of the actuator piston114. The oil transfer bearing120is coupled to the actuator piston114by a plurality of fasteners120A. In an embodiment, the oil transfer bearing120includes an oil channel122. In another embodiment, the oil transfer bearing120is attached to a static portion of the aircraft engine100. Oil is supplied to the oil transfer bearing120through an oil conduit124. For example, the oil is supplied from the oil conduit124to the oil transfer bearing120that in turn supplies oil to the oil channel122of the oil transfer bearing120. The oil from the oil channel122is supplied to a chamber112C (“fine chamber”) defined by a space between the actuator cylinder112and the actuator piston114. The oil supplied through the oil channel122into the chamber112C moves the actuator cylinder112backward towards the conical portion114B of the actuator piston114. On the other hand, supplying oil through a central opening channel123in a central part of the oil transfer bearing120to the chamber116A defined by the actuator cylinder support116moves the actuator cylinder112forward relative to the actuator piston114, as will be described further in detail in the paragraph below.

In an embodiment, the pitch change mechanism101further includes a static interface126(e.g., bellows) coupled to the oil transfer bearing120. The static interface126provides flexible support for the oil transfer bearing120. The static interface126allows the oil transfer bearing120to follow pitch change mechanism101movement while connected to the static part of the aircraft engine100.

In an embodiment, the pitch change mechanism101also includes a drain shield128. The drain shield128is coupled to the actuator cylinder112at one end128A and coupled to the conical portion114B of the actuator piston114at an opposite end128B. The end128A is a movable sealing interface at the cylinder outer diameter while the opposite end128B is fixed to the conical portion114B of the actuator piston114. The drain shield128is provided to shield or to isolate various components outside of the pitch change mechanism101in a case of an oil leak due to wearing of the sealing joint112B that is movable. In an embodiment, the pitch change mechanism101further includes guiding rods150. The guiding rods150are provided to tangentially locate the actuator cylinder112.

FIG.2shows a longitudinal cross-sectional view of the pitch change mechanism101with the blades102oriented in a feather position, according to an embodiment of the present invention. As shown inFIG.2, the feather position is an orientation of the blades102such that an edge102A of the blades102is facing an airflow200, or a face102B of the blades102is parallel to the airflow200. In the feather position, the actuator cylinder112is moved in a forward direction or to the left inFIG.2.

As shown inFIG.2, in the feather position, the actuator cylinder112is moved forward relative to the actuator piston114. To move the actuator cylinder112forward relative to the actuator piston114, oil at a certain pressure is provided to apply pressure on entire oil chamber114C and, thus, apply a force to a back surface110D of the cylindrical portion110C of the inner shaft110to move the actuator cylinder112forward.

FIG.3shows a longitudinal cross-sectional view of the pitch change mechanism101with the blades102oriented in a fine position, according to an embodiment of the present invention. As shown inFIG.3, the fine position is an orientation of the blades102such that the face102B of the blades102is generally perpendicular to the airflow200. In the fine position, the edge102A is facing generally perpendicular to the airflow200. As shown inFIG.3, in the fine position, the actuator cylinder112is moved backward relative to the actuator piston114. To move the actuator cylinder112backward relative to the actuator piston114, oil at a certain pressure is supplied through the oil conduit124to the oil transfer bearing120and through oil channel122to the chamber112C between the actuator cylinder112and the actuator piston114. The oil supplied through the oil channel122into the chamber112C applied a pressure to the entire chamber112C and, thus, applies a force (as shown by arrows300) on the actuator cylinder112, which moves the actuator cylinder112backwards. As the actuator cylinder114and the actuator cylinder support116are not movable, the oil in the chamber112C applies a force on a back wall112D of the actuator cylinder112to move the actuator cylinder112relative to the actuator piston114and the actuator cylinder support116.

In the fine position, the actuator cylinder112is moved to a backward direction or to the right inFIG.3. The blades102experience less drag in the feather position (shown inFIG.2) than in the fine position (shown inFIG.3).

The back wall112D has a surface area smaller than a surface area of chamber116A (“coarse chamber”). Therefore, for the same oil pressure, a greater magnitude force is generated by the actuator cylinder112to move the blades102into the feather position, whereas a lesser magnitude of force is generated by the actuator cylinder112to move the blades102into the fine position so as to ease actuation toward the feather (coarse) position.

The mechanical pitch lock118is provided as a fail-safe contingency when there is not sufficient oil pressure or an accidental drop of oil pressure occurs. In a case of a drop of oil pressure, the mechanical pitch lock118locks the pitch change mechanism101such that the orientation of the blades102is maintained.

The angle of the blades102relative to airflow200depends on flight conditions. Feather position is used to minimize drag. In normal operation, feather position is accomplished by means of a main engine oil pump201. In case of engine shut down, the feather position is accomplished using an auxiliary hydraulic oil pump202that is electrically driven.

The pitch change mechanism101described above provides various benefits:(a) No external movable seals are used in the chamber116A (coarse chamber), as any use of a movable seal may be worn overtime which could lead to external oil leak. Therefore, a static external seal is instead used in the coarse chamber. The term static external seal is used herein to mean that the position of the seal between two components is not changed, or the seal is not movable. i.e., the relative position of the seal between two components is not changed.(b) Guiding rods are provided to tangentially locate the actuator cylinder.(c) The blade position can be controlled by a blade position control system.(d) A closed control loop can be used by the blade position control system.(e) An oil transfer bearing (OTB)120provides three oil lines: (1) a coarse line that feeds the coarse chamber to cause movement toward the feather position, (2) a fine line that feeds the fine chamber to cause movement toward the fine position, and (3) a pitch lock (PL) line, that upon pressurizing the PL line, unlocks the mechanical pitch lock. A lack of pressure in the PL line causes the mechanical pitch lock to engage and to lock the pitch of the blades.(f) The oil transfer bearing (OTB) is supported by bearings and is exposed to the coarse chamber116A to reduce or eliminate the need of additional connecting systems to reduce weight and complexity and supply oil pressure to move the actuator cylinder112.

Further aspects of the present disclosure are provided by the subject matter of the following clauses.

A pitch change mechanism for an aircraft engine includes a unison ring, a plurality of crankshafts configured to receive a plurality of blades and each of the plurality of crankshafts having a longitudinal axis, an inner shaft coupled to the plurality of crankshafts and the unison ring, an actuator piston, and an actuator cylinder coupled to the inner shaft. The actuator cylinder configured to move relative to the actuator piston along a longitudinal axis of the pitch change mechanism. Movement of the actuator cylinder relative to the actuator piston is transferred to a rotation of each of the plurality of crankshafts around the longitudinal axis of each of the plurality of crankshafts to change a pitch of the plurality of blades.

The pitch change mechanism of the preceding clause, further including an oil transfer bearing, the actuator piston coupled to the oil transfer bearing to supply oil through the oil transfer bearing to move the actuator cylinder.

The pitch change mechanism of any preceding clause, further including a unison ring and a plurality of linkage yokes, each of the plurality of crankshafts coupled to the unison ring by a corresponding linkage yoke in the plurality of linkage yokes. The inner shaft is coupled to the unison ring.

The pitch change mechanism of any preceding clause, the unison ring coupled to the inner shaft by a plurality of fasteners.

The pitch change mechanism of any preceding clause, a diameter of the actuator cylinder being greater than a diameter of the actuator piston.

The pitch change mechanism of any preceding clause, further including an actuator cylinder support coupled to the actuator piston, the actuator cylinder support configured to support the actuator cylinder.

The pitch change mechanism of any preceding clause, the actuator cylinder support contacting the actuator cylinder via a first plurality of sealing joints at different points along the longitudinal axis of the pitch change mechanism.

The pitch change mechanism of any preceding clause, the first plurality of sealing joints coupled to the actuator cylinder support and being immovable when the actuator cylinder moves relative to the actuator piston.

The pitch change mechanism of any preceding clause, the actuator cylinder further contacting the actuator piston via a second sealing joint, the second sealing joint being movable with the actuator cylinder on a surface of the actuator piston relative to the actuator piston.

The pitch change mechanism of any preceding clause, further including a mechanical pitch lock provided within a chamber defined by the actuator cylinder support, the mechanical pitch lock configured to lock the pitch change mechanism.

The pitch change mechanism of any preceding clause, wherein the oil transfer bearing is provided within a chamber defined by the actuator piston, the oil transfer bearing having an oil conduit for supplying oil into a chamber defined by a space between the actuator cylinder and the actuator piston to move the actuator cylinder relative to the actuator piston.

The pitch change mechanism of any preceding clause, the oil transfer bearing provided within a chamber defined by the actuator piston.

The pitch change mechanism of any preceding clause, the inner shaft having a conical portion and a cylindrical portion connected to the conical portion, the conical portion extending radially to connect to the unison ring, the cylindrical portion configured to be enclosed within a chamber defined by the actuator cylinder.

The pitch change mechanism of any preceding clause, further including a drain shield coupled to the actuator cylinder and to the actuator piston, the drain shield configured to shield various components outside of the pitch change mechanism in case of an oil leak.

An aircraft engine including a plurality of blades and a pitch change mechanism. The pitch change mechanism includes a unison ring, a plurality of crankshafts configured to receive the plurality of blades and each of the plurality of crankshafts having a longitudinal axis, an inner shaft coupled to the plurality of crankshafts and the unison ring, an actuator piston, and an actuator cylinder coupled to the inner shaft. The actuator cylinder configured to move relative to the actuator piston along a longitudinal axis of the pitch change mechanism. Movement of the actuator cylinder relative to the actuator piston is transferred to a rotation of each of the plurality of crankshafts around the longitudinal axis of each of the plurality of crankshafts to change a pitch of the plurality of blades.

The aircraft engine of the preceding clause, the pitch change mechanism further including an oil transfer bearing, the actuator piston coupled to the oil transfer bearing.

The aircraft engine of any preceding clause, the pitch change mechanism further including an actuator cylinder support coupled to the actuator piston, the actuator cylinder support configured to support the actuator cylinder.

The aircraft engine of any preceding clause, the actuator cylinder support contacting the actuator cylinder via a first plurality of sealing joints at different points along the longitudinal axis of the pitch change mechanism.

The aircraft engine of any preceding clause, the first plurality of sealing joints coupled to the actuator cylinder support and are immovable when the actuator cylinder moves relative to the actuator piston.

The aircraft engine of any preceding clause, the actuator cylinder further contacting the actuator piston via a second sealing joint, the second sealing joint being movable with the actuator cylinder on a surface of the actuator piston relative to the actuator piston.

The aircraft engine of any preceding clause, wherein the pitch change mechanism further includes a mechanical pitch lock provided within a chamber defined by the actuator cylinder support, the mechanical pitch lock configured to lock the pitch change mechanism.

The aircraft engine of any preceding clause, wherein the aircraft engine is an open fan engine, an unducted fan engine, or a propeller engine having blades provided outside a nacelle of the aircraft engine.

The aircraft engine of any preceding clause, wherein each of the plurality of blades is linked to a corresponding one of the plurality of crankshafts of the pitch change mechanism.

A method of changing a pitch of a plurality of blades in an aircraft engine using a pitch change mechanism having a unison ring, a plurality of crankshafts coupled to the unison ring and configured to receive the plurality of blades, each of the plurality of blades being linked to a corresponding one of the plurality of crankshafts, each of the plurality of crankshafts having a longitudinal axis, an inner shaft coupled to the plurality of crankshafts and the unison ring, an actuator piston, and an actuator cylinder coupled to the inner shaft. The method includes moving the actuator cylinder relative to the actuator piston along a longitudinal axis of the pitch change mechanism. The method further includes transferring movement of the actuator cylinder relative to the actuator piston to a rotation of each of the plurality of crankshafts around a longitudinal axis of each of the plurality of crankshafts to change a pitch of the plurality of blades.

The method of the preceding clause, the pitch change mechanism further including an oil transfer bearing, the actuator piston coupled to the oil transfer bearing.

The method of any preceding clause, the pitch change mechanism further including an actuator cylinder support coupled to the actuator piston, the actuator cylinder support configured to support the actuator cylinder.

The method of any preceding clause, the actuator cylinder support contacting the actuator cylinder via a first plurality of sealing joints at different points along the longitudinal axis of the pitch change mechanism.

The method of any preceding clause, the first plurality of sealing joints coupled to the actuator cylinder support and are immovable when the actuator cylinder moves relative to the actuator piston.

The method of any preceding clause, the actuator cylinder further contacting the actuator piston via a second sealing joint, the second sealing joint being movable with the actuator cylinder on a surface of the actuator piston relative to the actuator piston.

The method of any preceding clause, wherein the pitch change mechanism further includes a mechanical pitch lock provided within a chamber defined by the actuator cylinder support, the mechanical pitch lock configured to lock the pitch change mechanism.

The method of any preceding clause, wherein the aircraft engine is an open fan engine, an unducted fan engine, or a propeller engine having blades provided outside a nacelle of the aircraft engine.

The method of any preceding clause, wherein each of the plurality of blades is linked to a corresponding one of the plurality of crankshafts of the pitch change mechanism.

Although the foregoing description is directed to the preferred embodiments of the present disclosure, other variations and modifications will be apparent to those skilled in the art, and may be made without departing from the spirit or the scope of the disclosure. Moreover, features described in connection with one embodiment of the present disclosure may be used in conjunction with other embodiments, even if not explicitly stated above.