Extension removal tool

A tool assembly for disassembling a crankshaft assembly with a main shaft received within a hollow extension shaft along a shaft axis and coupled thereto via an interference fit, the extension shaft having a fastener slot. The tool assembly includes a main tool body having a central bore, a main tool body inner surface circumscribing the central bore, and a main tool body outer surface having a fastener bore, the central bore dimensioned for axially receiving the extension shaft, with the fastener bore axially aligned with the extension shaft fastener slot. A fastener is concurrently fastenable to the main tool body via the fastener bore and the hollow extension shaft via the fastener slot. An actuator assembly with a linearly-displacing actuating element is coupled to the main tool body and applies a force, via the actuating element, against an end of the main shaft in a direction along the axis.

TECHNICAL FIELD

The disclosure relates generally to aircraft engines, and, more particularly, to the disassembly of crankshafts in aircraft engines.

BACKGROUND

In some aircraft engines, for instance those including one or more rotary internal combustion engines, a crankshaft may be provided with eccentric lobes and an extension portion joined to a main crankshaft portion at an interference fit. Such crankshaft assemblies may be suitable for their intended purposes, however improvements are always desirable.

SUMMARY

In one aspect, there is provided a tool assembly for disassembling a crankshaft assembly, the crankshaft assembly including a main shaft received within a hollow extension shaft along a shaft axis and operatively coupled to the extension shaft via an interference fit, the hollow extension shaft having an extension shaft fastener slot, the tool assembly comprising: a main tool body having a main tool body central bore, a main tool body inner surface circumscribing the main tool body central bore, and a main tool body outer surface having a main tool body fastener bore, the main tool body central bore dimensioned for axially receiving the hollow extension shaft within the main tool body central bore, with the main tool body fastener bore axially aligned with the extension shaft fastener slot; a fastener dimensioned to be concurrently fastened to the main tool body via the main tool body fastener bore and the hollow extension shaft via the extension shaft fastener slot; and an actuator assembly with a linearly-displacing actuating element operatively coupled to the main tool body and operable for applying a force, via the linearly-displacing actuating element, against an end of the main shaft in a first direction from the actuator assembly towards the end of the main shaft along the shaft axis.

In another aspect, there is provided a method of disassembling a shaft assembly including a first shaft operatively coupled to a second shaft via an interference-fit linkage and extending along a shaft axis, comprising: installing a shaft removal tool to the shaft assembly, including installing a fastener to operatively couple the shaft removal tool to the second shaft; and using the shaft removal tool, separating the first shaft from the second shaft by applying a pushing force against the first shaft in a first direction along the shaft axis, the pushing force causing the shaft removal tool to apply a pulling force, in response to the pushing force, against the second shaft in a second direction along the shaft axis opposite the first direction via the fastener to overcome a frictional force at the interference-fit linkage.

In a further aspect, there is provided a system for disassembling a crankshaft assembly, comprising: a main shaft having a main shaft radially outer surface extending from a main shaft first end to a main shaft second end along a shaft axis, the main shaft radially outer surface including a main shaft frustoconical portion along a length of the main shaft, the main shaft being rotatable about the shaft axis and axially fixed in place; an extension shaft having an extension shaft central bore, an extension shaft radially inner surface circumscribing the extension shaft central bore, and an extension shaft radially outer surface extending between an extension shaft first end and an extension shaft second end along the shaft axis, the extension shaft radially inner surface including an extension shaft frustoconical portion, the main shaft receivable within the extension shaft central bore with the main shaft frustoconical portion engaging the extension shaft frustoconical portion at a frustoconical linkage, the extension shaft further including an extension shaft fastener slot eccentrically disposed on the extension shaft radially outer surface; a main tool body having a main tool body central bore, a main tool body radially inner surface circumscribing the main tool body central bore, and a main tool body radially outer surface having a main tool body fastener bore, the extension shaft receivable within the main tool body central bore with the main tool body fastener bore axially aligned with the extension shaft fastener slot; a fastener dimensioned to be concurrently fastened to the main tool body via the main tool body fastener bore and the extension shaft via the extension shaft fastener slot; and an actuator assembly with a linearly-displacing actuating element operatively coupled to the main shaft first end, the actuator operable to apply a force, via the linearly-displacing actuating element, against the main shaft in a first direction from the actuator assembly towards the main shaft first end along the shaft axis.

DETAILED DESCRIPTION

FIG.1illustrates an exemplary hybrid electric powerplant system100of a type preferably provided for use in subsonic flight. The system100includes a thermal engine102operatively connected to drive a load such as a propeller104. An electric motor106is operatively connected to the thermal engine102to drive the propeller104together with the thermal engine102. A transmission108, e.g. including a combining gear box and/or reduction gear box, connects the thermal engine102and the electric motor106in parallel to drive the propeller104. Illustratively, the propeller is a variable pitch propeller, wherein a variable pitch control110can rotate the blades112to various different pitch angles. A disconnect can be included between each torque source102,106that can be located either in the transmission108or at the output of the individual torque source102,106. The thermal engine102may include one or more rotary internal combustion engines operatively coupled to the propeller104directly or indirectly via a crankshaft assembly200(seeFIG.2). Other thermal engine types may be contemplated. In some embodiments, other powerplant systems, for instance powered solely by a thermal engine and/or operatively coupled to another thrust-generating device, may be contemplated.

FIGS.2A-2Billustrate an exemplary crankshaft assembly200for the thermal engine102of system100. In some cases, the thermal engine102includes a plurality of rotary internal combustion engines drivingly coupled to the crankshaft assembly200for transmitting rotary motion to the propeller104(or another like thrust-generating device). In such cases, for instance where four or more rotary engines are drivingly coupled to the crankshaft assembly200, the crankshaft assembly200may be formed of multiple sections, for instance to withstand the loads and provide sufficient length for the numerous operatively-coupled rotary engines. In the shown case, the crankshaft assembly200includes a main shaft210(also referred to as a first shaft) operatively coupled to an extension shaft220(also referred to as a second shaft) via an interference fit (e.g., a frustoconical linkage). In other cases, additional extension shafts may be provided, for instance where additional rotary engines are operatively coupled to the crankshaft assembly200.

The main shaft210extends from a main shaft first end211to a main shaft second end (not shown) along a shaft axis A and includes eccentrically-shaped lobes (not shown) at positions along its length where the rotary engines are operatively coupled. While the main shaft210is shown to be solid, in some cases the main shaft210may include a hollow core and/or various passages passing therethrough. The main shaft210includes a main shaft radially outer surface212with a main shaft frustoconical portion213disposed thereon. Stated differently, an outer diameter of the main shaft210increases along the shaft axis A at the main shaft frustoconical portion213. A tangent line at the main shaft frustoconical portion213may form an angle with the shaft axis A that may vary. In some cases, this angle may be about 7 degrees.

The extension shaft220illustratively extends from an extension shaft first end221to an extension shaft second end222along a shaft axis A and may include eccentrically-shaped lobes at positions along its length where the rotary engines are operatively coupled. In other cases, the eccentrically-shaped lobes may only be present on the main shaft210, with the extension shaft220providing the additional required length. The extension shaft220is shown to have an extension shaft central bore223from the extension shaft first end221to the extension shaft second end222, and is circumscribed by an extension shaft radially inner surface224. The extension shaft220may thus be said to be hollow. The extension shaft radially inner surface224includes an extension shaft frustoconical portion225disposed thereon, which may correspond (i.e., have a like tangent angle relative to the shaft axis A) to the main shaft frustoconical portion213for mating engagement between the main shaft210and the extension shaft220. The extension shaft220includes an extension shaft radially outer surface226with an extension shaft fastener slot227eccentrically disposed thereon, as will be discussed in further detail below.

FIG.2Ashows the crankshaft assembly200in an assembled configuration or state, whereby the main shaft210is inserted in the extension shaft central bore223, with the main shaft radially outer surface212engaged with the extension shaft radially inner surface224, and the main shaft frustoconical portion213engaged with the extension shaft frustoconical portion225. The engagement between the main shaft frustoconical portion213and the extension shaft frustoconical portion225(which may be referred to as a frustoconical linkage230) may provide the principle retention force between the main shaft210and the extension shaft220, i.e., a high level of friction to overcome to separate the main shaft210from the extension shaft220to achieve a disassembled configuration or state of the crankshaft assembly200(shown inFIG.2B). Other interference fits between the main shaft210and extension shaft220having a high level of friction to be overcome may be contemplated. Of note, in the disassembled configuration of the crankshaft assembly200, the extension shaft may be said to extend from extension shaft first end221to extension shaft second end222along an extension shaft axis A′.

Referring toFIG.3, an exemplary tool assembly300is shown for disassembling the crankshaft assembly200. The depicted tool assembly300includes a main tool body310(also referred to as a puller body) operatively couplable to the crankshaft assembly200, a fastener320for fastening the tool assembly300to the extension shaft220, and an actuator assembly330for applying the necessary forces to disassemble the crankshaft assembly200. Other components may be included with the tool assembly300, such as a protective sleeve340and a fastener protective element350, as will be discussed in further detail below. The tool assembly300and crankshaft assembly200may be collectively referred to as a system for disassembling a crankshaft. As will be discussed in further detail below, the tool assembly300may engage the crankshaft assembly200, and in particular the main shaft210, at the main shaft first end211. This may provide access to the crankshaft assembly200while avoiding other locations along the length of the crankshaft assembly200that may be difficult to access and/or have adjacent components with critical surfaces susceptible to damage.

Referring jointly toFIGS.3and4A-4E, the main tool body310includes a main tool body central bore311for engaging the crankshaft assembly200(in particular for receiving the extension shaft220). A main tool body radially inner surface312circumscribes the main tool body central bore311, while a main tool body radially outer surface313has an eccentric portion extending therefrom, the eccentric portion including a main tool body fastener bore314extending therein in parallel to the central axis of the main tool body310. The main tool body fastener bore314is alignable with the extension shaft fastener slot227so that the fastener320may be received in both the main tool body fastener bore314and the extension shaft fastener slot227to secure the main tool body310to the extension shaft220. In some cases, the fastener320is a threaded fastener, with both the main tool body fastener bore314and the extension shaft fastener slot227being internally threaded. In such cases, the fastener320may be insertable through the main tool body fastener bore314and the extension shaft fastener slot227in a direction parallel to the shaft axis A (illustratively along slot axis S). The dimensions of the fastener320may vary, for instance based on the sizes of the components being fastened together. The fastener320may have various strength requirements, for instance to withstand a pulling force of the tool assembly300acting against the extension shaft220, as will be discussed in further detail below. Other fastener types and securing means to the main tool body310and extension shaft220may be contemplated. It is also understood that more than one fastener could be used.

As discussed above, the actuator assembly330is operable for applying the necessary forces to disassemble the crankshaft assembly200. The depicted actuator assembly330includes an outer cylinder331that remains static during actuation and an inner cylinder332, also referred to as a linearly-displacing actuating element, movably disposed within the outer cylinder332to perform the actuation movement. The outer cylinder331and inner cylinder332may be collectively referred to as a fluid driven actuator or cylinder such as a hydraulic cylinder, although other actuation means may be contemplated. The actuator assembly330is mountable or couplable to the main shaft210at the main shaft first end211to apply a pushing force against the main shaft210in a first direction along the shaft axis A. In addition, the actuator assembly330is mountable or couplable to the main tool body310to provide a reactionary pulling force against the extension shaft220, via the fastener320, in a second direction along the shaft axis A opposite the first direction, thereby overcoming the frictional force at the frustoconical linkage230and separating the extension shaft220from the main shaft210.

In the shown case, the actuator assembly330includes a reaction pad333for transferring the pushing force from the inner cylinder332to the main shaft210. The reaction pad333may have internal threading for fastening to an externally threaded portion of the main shaft first end211, thereby securing the reaction pad333to the main shaft first end211and preventing accidental dislodgement. Other fastening means may be contemplated. As shown inFIG.4B, the reaction pad333may have a diameter corresponding to a diameter of the main tool body radially inner surface312.

According to some embodiments, the actuator assembly330further includes a cylindrical adapter334for operatively coupling the outer cylinder331to the main tool body310. The depicted cylindrical adapter334includes a central bore with two sets of internal threading: a first set for engaging with external threading on the outer cylinder331, and a second set for engaging with external threading on the main tool body310. The first and second sets of threading thus correspond to thread patterns on the outer cylinder331and main tool body310, respectively. In some cases, the first and second sets of threading may be different from one another and the cylindrical adapter334may be said to be unidirectional. In other cases, the first and second sets of threading may be identical, and the cylindrical adapter334may be reversible. The internal diameter of the cylindrical adapter334may vary, for instance if the outer cylinder331and main tool body310have different external diameters. Actuation of the inner cylinder332may cause the outer cylinder331to displace along the shaft axis A, as will be discussed in further detail below, thereby allowing the main tool body310and attached extension shaft220to displace as well along the shaft axis A. Other devices for coupling the outer cylinder331to the main tool body310may be contemplated.

As discussed above, in the shown case, a protective sleeve340may be provided for protecting the various components and helping the various components react to the applied forces by helping maintain the applied forces in a linear (i.e., along shaft axis A) direction. The protective sleeve340, for instance a plastic head bushing, may be radially disposed between the extension shaft220and the main tool body310and prevent the applied forces from inadvertently applying undesirable bending moments against the crankshaft assembly200. In addition, a fastener protective element350may be used for protecting against inadvertent dislodgement of a portion of the fastener320. In the shown case, the fastener protective element350is a separate component that is mounted to the main tool body radially outer surface313(illustratively via fasteners351). In other cases, the fastener protective element350may be integrally formed with the main tool body310. The fastener protective element350may be disposed adjacent to and aligned with the installed fastener320to block or catch a dislodged portion of the fastener320(e.g., an errant head of a threaded fastener). Various sizes and shapes for the fastener protective element350may be contemplated.

Referring toFIGS.4A-4E, the present disclosure teaches an exemplary method of disassembling a crankshaft assembly200including a first shaft (e.g., main shaft210) operatively coupled to a second shaft (e.g., extension shaft220) via a frustoconical linkage230and extending along a shaft axis A. A shaft removal tool (e.g., tool assembly300) is installed to the crankshaft assembly200, including installing a fastener320to operatively couple the shaft removal tool300to the second shaft220. A pushing force is applied against the first shaft210in a first direction along the shaft axis A, the pushing force causing the shaft removal tool300to apply, in response to the pushing force, a pulling force against the second shaft220in a second direction along the shaft axis A opposite the first direction via the fastener320to overcome a frictional force at the frustoconical linkage230to separate the first shaft210from the second shaft220.

Referring toFIG.4A, the crankshaft assembly200is shown in its assembled configuration (i.e., the main shaft210is inserted in the extension shaft central bore223with the frustoconical linkage230maintaining the connection between the main shaft210and the extension shaft220via the frictional force. To begin the disassembly process, the reaction pad333may be secured to the main shaft first end211.

Referring toFIGS.4B-4C, the tool assembly300is operatively coupled or mounted to the crankshaft assembly200. In particular, the extension shaft220and reaction pad333are received within the main tool body central bore311, with the protective sleeve340radially disposed between the extension shaft220and the main tool body310. The main tool body fastener bore314is axially aligned with the extension shaft fastener slot227along the slot axis S, and the fastener320is inserted through the main tool body fastener bore314and the extension shaft fastener slot227to operatively couple the main tool body310to the extension shaft220. The fastener protective element350may then be mounted to the main tool body310and axially aligned with the inserted fastener320(i.e., along slot axis S) to block or deflect a broken projectile portion of the fastener320, for instance in a case of failure.

Referring toFIG.4D, the actuator assembly330is mounted to the tool assembly300, with both the outer cylinder331of the hydraulic actuator and the main tool body310fastened to the cylindrical adapter334. InFIG.4D, the inner cylinder332is shown in its retracted (or non-actuated) position.

Referring toFIG.4E, the hydraulic actuator is activated, for instance via an external control signal, and the inner cylinder displaces along the shaft axis A in the first direction to apply a pushing force against the reaction pad333, which concurrently transfers the pushing force to the main shaft210at the main shaft first end211. As the main shaft210is operatively coupled to the various rotary engines and is thus axially fixed in place, the pushing force is transferred to an equal-but-opposite pulling force by the main tool body310against the extension shaft220, via the fastener320, along the shaft axis A in a direction opposite the pushing force. This pulling force is sufficient to overcome the friction force at the frustoconical linkage230to separate the extension shaft220from the main shaft210, thereby disassembling the crankshaft assembly200.

In some embodiments, the tool assembly200is operable to overcome frictional forces at the frustoconical linkage230of up to 20,000 pounds, and withstand the transfer of these forces. Other force requirements may be contemplated.

According to some embodiments, there is provided a tool assembly for disassembling a crankshaft assembly including an axially fixed in place main shaft receivable within a hollow extension shaft along a shaft axis and operatively coupled to the extension shaft via a frustoconical linkage. The tool assembly comprises a main tool body having a main tool body central bore, a main tool body radially inner surface circumscribing the main tool body central bore, and a main tool body radially outer surface having a main tool body fastener bore, the extension shaft receivable within the main tool body central bore with the main tool body fastener bore axially alignable with an extension shaft fastener slot eccentrically disposed on an extension shaft radially outer surface. The tool assembly further comprises a fastener concurrently fastenable to the main tool body via the main tool body fastener bore and the extension shaft via the extension shaft fastener slot, and an actuator assembly operatively couplable to the main tool body and operable for applying a pushing force against an end of the main shaft in a first direction along the shaft axis. The main tool body, in response to the pushing force against the end of the main shaft, applies a pulling force against the extension shaft in a second direction along the shaft axis opposite the first direction, via the fastener, to overcome a frictional force at the frustoconical linkage and separate the extension shaft from the main shaft along the shaft axis.