Internal surface treatment device for hollow engine shaft and the like

A surface treatment device for applying a surface treatment to an inner surface of a hollow engine shaft includes a supply of a surface treatment agent and an elongated rod extending from a proximal end to a distal end. The rod has an inner passage extending from the proximal end to the distal end. The proximal end has an inlet fluidly coupled to the supply. The inner passage terminates at an outlet at the distal end. The rod is insertable inside the shaft. An input device is operable for controlling a delivery of a predetermined quantity of the surface treatment agent from the supply. An applicator disposed at the distal end of the rod adjacent the outlet is engageable with the inner surface of the shaft for applying, upon activation of the input device, the predetermined quantity of the surface treatment agent to the inner surface of the shaft.

TECHNICAL FIELD

The disclosure relates to a device and a method for applying a surface treatment, such as paint, to the inner surface of hollow engine shafts and the like.

BACKGROUND

Hollow shafts used for aircraft engines and the like may be coated. For instance, these shafts may be painted to prevent corrosion. Due to their size, access to the inner surface of these shafts may be limited, and known techniques for protecting the outer shaft surfaces, for instance via paint guns, may not be suitable.

SUMMARY

In one aspect, there is provided a surface treatment device for applying a surface treatment to an inner surface of a hollow engine shaft, comprising a supply of a surface treatment agent, an elongated rod extending from a proximal end to a distal end, the elongated rod having an inner passage extending from the proximal end to the distal end, the proximal end having an inlet fluidly coupled to the supply of the surface treatment agent, the inner passage terminating at an outlet at the distal end, the elongated rod insertable inside the hollow engine shaft, an input device operable for controlling a delivery of a predetermined quantity of the surface treatment agent from the supply of the surface treatment agent, and an applicator disposed at the distal end of the elongated rod adjacent the outlet, the applicator engageable with the inner surface of the hollow engine shaft for applying, upon activation of the input device, the predetermined quantity of the surface treatment agent from the supply of the surface treatment agent to the inner surface of the hollow engine shaft.

In another aspect, there is provided a coating rod for applying a predetermined quantity of a coating liquid to an inner surface of a hollow engine shaft, comprising an elongated body extending longitudinally from a first end to a second end, the elongated body sized and configured for axial insertion inside the hollow engine shaft, an inner passage extending longitudinally through the elongated body, the inner passage having a coating inlet at the first end and a coating outlet at the second end, an input device for activating a delivery of the predetermined quantity of the coating liquid, and a coating applicator disposed at the second end adjacent the coating outlet.

In a further aspect, there is provided a method for treating an inner surface of a hollow engine shaft, comprising engaging an elongated rod inside the hollow engine shaft, the elongated rod having a distal end carrying an applicator, directing a predetermined quantity of a surface treatment agent through an inner passage of the elongated rod towards the distal end, releasing the predetermined quantity of the surface treatment agent from an outlet of the inner passage of the elongated rod inside the hollow engine shaft, and spreading the predetermined quantity of the surface treatment agent along the inner surface of the hollow engine shaft with the applicator.

DETAILED DESCRIPTION

FIG.1illustrates a gas turbine engine10of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication, along central longitudinal axis11, a fan12through which ambient air is propelled, a compressor section14for pressurizing the air, a combustor16in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section18for extracting energy from the combustion gases. While the depicted engine10is a turbofan engine, the present disclosure is applicable to other types of engines, such as turbojet, turboprop, and turboshaft engines, as well as hybrid-electric engines.

Referring toFIG.2, an exemplary hollow shaft20used in the engine10is shown. Shaft20may be, for instance, a main shaft for the engine10, a power turbine shaft for the turbine section18, or a low pressure shaft drivingly coupling a low pressure compressor of the compressor section14to a low pressure turbine of the turbine section18. Other hollow shafts of the engine10may be contemplated. The shaft20may be made from steel or other like materials. Other materials may be contemplated as well. The shaft20extends along a shaft longitudinal axis A from a first end22to a second end24. The shaft20has a hollow cylindrical body with an outer surface26and an inner surface28radially disposed within the outer surface26.

In the shown case, the shaft20is made up of two sections having inner surfaces28with different inner diameters: a first section30of axial length L1having a first inner diameter D1, and a second section32of axial length L2having a second inner diameter D2for its inner surface28. A transition portion34of axial length L3, for instance a tapered or frustoconical portion, joins the first section30to the second section32. An overall axial length L of the shaft20may include the first section axial length L1, the second section axial length L2, and the transition portion axial length L3. In the shown case, the second inner diameter D2is greater in magnitude than the first inner diameter D1, although the opposite arrangement may be contemplated. Similarly, in the shown case, the second section axial length L2is greater in magnitude than the first section axial length L1, although the opposite may be contemplated.

Various combinations of diameters and lengths for each section30,32may be contemplated. While the shown shaft20includes two main sections30,32, the present disclosure is applicable to shafts20with other numbers of sections having different inner diameters, for instance three or more sections of different axial lengths and inner diameters. Similarly, the present disclosure is applicable to a shaft20having a constant inner diameter along its axial length (i.e., a single section shaft). In some cases, the shaft20may have an axial length L ranging from 20 to 80 inches long, with an inner diameter ranging from 0.360 to 1.400 inches. Other shaft lengths and diameters may be contemplated.

Referring additionally toFIG.3, a surface treatment device40is shown for applying a surface treatment agent42(e.g., paint/liquid coating) stored in a surface treatment supply44to an inner surface28of a shaft20, for instance the shaft20ofFIG.2, according to one or more embodiments of the present disclosure. Still according to one or more embodiments, the surface treatment agent42may be paint, with the surface treatment device40operable to apply a uniform layer or coating of paint to the inner surface28of the shaft20to protect the inner surface28of the shaft from corrosion. Other surface treatment agents42may be contemplated, for instance protective liquid coatings, such as a rust-proofing coating.

The surface treatment device40depicted inFIG.3includes an elongated rod46, also referred to as a coating rod, having an elongated body of diameter D3extending longitudinally from a proximal end48(also referred to as a first end) to a distal end50(also referred to as a second end), with an inner passage52extending longitudinally centrally through the elongated rod46from the proximal end48to the distal end50. At the proximal end48, there is an inlet54(also referred to as a coating inlet) to the inner passage52fluidly coupled to the surface treatment supply44, illustratively via a flexible conduit or hose56. At the distal end50, the inner passage52terminates at an outlet58(also referred to as a coating outlet). Various outlet types may be contemplated, as will be discussed in further detail below. The surface treatment agent42(e.g., the paint or liquid coating substance) is shown as flowing through the inner passage52, defining a general surface treatment flow direction from the proximal end48to the distal end50.

An applicator60(also referred to as a coating applicator) is disposed at the distal end50adjacent the outlet58. In the embodiment shown inFIG.3, the applicator is directly fluidly coupled to the outlet58and is thus configured for receiving the surface treatment agent42directly therefrom. Stated differently, the inner passage52terminates, at the distal end50, directly at the applicator60such that the surface treatment42from the surface treatment supply44is supplied, via the inner passage52, directly to the applicator60. As such, the surface treatment device40is operable for coating the inner surface28of the exemplified engine shaft20by supplying the surface treatment agent42, from the supply44, through the inner passage52of the elongated rod46to the applicator60at the distal end50thereof, via the outlet58, to apply the surface treatment agent42to the inner surface28. The rod diameter D3may be sized to be smaller in magnitude than the smallest of the hollow shaft20interior diameters, illustratively D1in the shaft20shown inFIG.2, so that the elongated rod46may be easily inserted into the hollow shaft20along shaft axis A.

The elongated rod46may be made from, for instance, steel, aluminum, or a hard plastic. Other materials may be contemplated as well. In the shown case, the device40includes a handle62at the proximal end48with an input device64such as one or more control buttons64(e.g., push-button or trigger) for controlling the delivery of the surface treatment agent42from the surface treatment supply44to the applicator60. Various delivery means from the supply44to the elongated rod46may be contemplated, as will be discussed in further detail below. A visual indicator66, for instance a light or a screen, may provide or present a status of the provision of surface treatment agent42, as will be discussed in further detail below.

As will be discussed in further detail below, the surface treatment device40is operable to deliver a predetermined quantity or volume of the surface treatment agent42from the surface treatment supply44to the inner surface28of the hollow engine shaft20. The applicator60may thus apply a consistent layer of surface treatment agent42(e.g., a consistent paint or coating thickness) along the axial length L of the shaft20, as the quantity of surface treatment agent42required for this application may be predetermined and metered. Various predetermination and metering means may be contemplated, as will be discussed in further detail below. As such, the uniformity of a painting/coating process for a given shaft20, as well as the repeatability of a painting/coating process for different shaft sections30,32or for multiple shafts20, may be improved. For instance, a thickness of the coating liquid, for instance paint, may be consistent along the axial length L of the shaft20(i.e., minimal variation of the thickness along the axial length L). In some cases, the desired coating thickness may range from 0.015 to 0025 inches. Other coating thicknesses may be contemplated, for instance based on the material of the shaft20and the type of liquid coating applied as the surface treatment agent42.

In the embodiment shown inFIG.3, the surface treatment device40includes a single applicator60mounted to the distal end50of the elongated rod46, although the number of applicators60may vary. In the shown case, the applicator60is a sponge, i.e., an applicator60able to expand and contract based on its surroundings. Other applicators60may be contemplated, for instance a brush. The porosity of the sponge may vary, for instance based on a desired final paint texture on the inner surface28. The sponge may be sized to span a greater diameter than the greatest inner diameter of the hollow shaft20(illustratively D2of the hollow shaft20ofFIG.2) and be compressible to easily slide within the section of the hollow shaft20having the smallest inner diameter (illustratively D1of the hollow shaft20ofFIG.2). As such, the wet or saturated sponge may apply the surface treatment agent42in all directions to the inner surface28, providing a consistent application of the surface treatment agent42. Such application may be accomplished, for instance, via a reciprocating motion of the elongated rod46along the shaft axis A, with metered quantities surface treatment agent42being provided to the applicator60(e.g., to the compressed sponge) for a specific inner surface28(or section of an inner surface28), with the provision of additional surface treatment agent42available as needed.

Referring toFIG.4, another embodiment of a surface treatment device40for applying a surface treatment agent42stored in a surface treatment supply44to the inner surface28of the shaft20is shown, with like reference numerals referring to like elements. In this embodiment, the outlet58includes a plurality of nozzles58. In the shown case, two applicators60are disposed at the distal end50of the elongated rod46, one in front of the other, with an axial gap G disposed therebetween. Nozzles58, illustratively four nozzles58, are disposed in the axial gap G and are aimed towards the applicators60. Other numbers of applicators60and nozzles58may be contemplated. In the shown case, the nozzles58are aimed directly at the applicators60. The nozzles58are therefore operable to deliver a metered quantity of surface treatment agent42, such as paint and liquid coating, directly to the applicator60(i.e., to wet or saturate the applicator60) so that the applicator60may be used to coat the inner surface28of the shaft20. In other cases, the nozzle(s)58may be aimed radially outwardly, i.e. towards the inner surface28of the shaft20directly. In such cases, the applicators60may be used to spread the surface treatment agent42that is sprayed onto the inner surface28by the nozzle(s)58. Other numbers and directions of nozzles58may be contemplated, for instance nozzles58operable to spray coating liquid in both upstream and downstream directions. As such, an axial width of the gap G may vary.

The coating device40ofFIG.4is therefore operable to coat/paint the inner surface28of the shaft20via two distinct applicators60. This may increase the surface area of the inner surface28that may be coated in each stroke of the elongated rod46. Other numbers of applicators60and nozzles58may be contemplated. For instance, one larger (i.e., occupying a larger axial length along the elongated rod46) applicator60may be disposed towards the distal end50of the elongated rod46, with one or more nozzles58disposed on the elongated rod46on both upstream and downstream sides of the applicator60. In other cases, the one or more nozzles58may be aimed radially outwardly, i.e. towards the inner surface28of the shaft20directly. In such cases, the applicators60may be used to spread the surface treatment agent42that is sprayed onto the inner surface28by the nozzle(s)58. Various nozzle types may be contemplated, for instance a flat fan distribution nozzle, a conical distribution nozzle, or a single point distribution nozzle.

Various combinations of the surface treatment devices40shown inFIGS.3and4may be contemplated. For instance, the number of applicators60and the outlet58type may vary. For instance, whileFIG.3shows a surface treatment device40having a single applicator60directly fluidly coupled to the outlet58, in other cases the surface treatment device40may include two applicators60axially spaced apart at the distal end50and each directly fluidly coupled to outlets58of the inner passage52. Likewise, whileFIG.4shows a surface treatment device40having two applicators60axially spaced apart with a plurality of nozzles58disposed in an axial gap G therebetween, in other cases the surface treatment device40may include a single applicator60disposed at the distal end50with one or more nozzles58disposed upstream or downstream of the applicator60. Other such combinations may be contemplated.

Referring toFIG.5, an exemplary block diagram for the surface treatment supply44is shown. The surface treatment agent42may be stored in a receptacle68. Various filling means (represented inFIG.5by “Fluid in”) may be contemplated, for instance manually filling the receptacle68as needed or an automatic delivery system of surface treatment agent42by another source (not shown). Surface treatment agent42may exit the receptacle68(represented inFIG.5by “Fluid out”) via the conduit56ofFIGS.3and4. As discussed above, various tubes or conduits may be contemplated. A timer70and flow meter72may be provided for controlling or metering the quantity or volume of surface treatment agent42to be delivered to the applicator60. A fluid pump74may be provided to deliver the surface treatment agent42to the applicator60, as will be discussed in further detail below. A power supply76may provide power for the timer70, flow meter72and/or fluid pump74. The power supply76may be an on-board power supply (e.g., a battery) or may be the main electric grid. In some cases, different components of the surface treatment supply44may receive power from different sources. While the timer70is illustratively shown to be included in the surface treatment supply44, in other cases it may be integrated directly in the handle62.

As discussed above, the surface treatment supply44is operable to deliver a predetermined or metered quantity of surface treatment agent42to the applicator60. Various means for this predetermination and metering may be contemplated. For instance, a correlation between a desired or required thickness of the surface treatment agent42applied to the inner surface28and a quantity or volume of surface treatment agent42may be determined by taking into account the above-mentioned desired or required thickness, an axial length of the section of the shaft20to which the surface treatment agent42is to be applied, and an inner diameter of this section of the shaft20. This predetermined quantity may be referred to as a minimum or baseline quantity of surface treatment agent42required, as multiple iterations of surface treatment processes may be required to determine an actual required quantity, which may be higher than the predetermined quantity.

To deliver the predetermined quantity of surface treatment agent42to the applicator, a user may engage the input device64to begin a delivery procedure, the input device64operatively coupled to the surface treatment supply44. Upon engaging the input device (e.g., pressing a button64on the handle62), the fluid pump74may engage and operate until a signal is received from the timer70and/or the flow meter72indicative of the predetermined quantity of surface treatment agent42being evacuated from receptacle68. For instance, the flow meter72may be disposed between the receptacle68and the elongated rod46and make this determination based on the flow rate of the surface treatment agent42exiting the receptacle68and an elapsed period of time (e.g., based on the timer70). In other cases, if a flow rate of the fluid pump74is known, a period of time required to deliver the predetermined quantity of surface treatment agent42may be similarly predetermined, and the timer70may thus send a signal to cease delivery of surface treatment agent once this period of time has elapsed. Other metering and predetermining means may be contemplated.

Various numbers and types of input devices64may be contemplated. The surface treatment devices40shown inFIGS.3and4illustratively include two buttons64mounted to the handle62. Each button64may, for instance, be operable to control a metered quantity of surface treatment agent42to a specific section of the hollow engine shaft20. Stated differently, each button64may engage a new countdown from one or more timers70. For instance, as discussed above, the exemplary hollow engine shaft20as shown inFIG.2includes two sections30,32, with the first section having an inner diameter D1and axial length L1that are each inferior to an inner diameter D2and axial length L2of the second section32. An inner surface area of the second section32, and thus an area to be treated with surface treatment agent42, is therefore of greater magnitude than an similar area to be treated of the first section30. As such, if the inner surface28is to have a same thickness of surface treatment agent42applied thereto, a greater quantity (or portion) of surface treatment agent42is to be delivered to the applicator60for spreading the surface treatment agent42to the second section32than the portion or quantity of surface treatment agent42delivered to the first section30. More generally, each button64may be operable to deliver a predetermined quantity of surface treatment to the applicator60corresponding to a particular section of the hollow engine shaft20to have its inner surface28treated. These same buttons64, or additional buttons, may have additional functions for manual override of the delivery of surface treatment agent42, for instance to cease a delivery procedure midway, or to provide additional surface treatment agent42when required. The buttons64may be, for instance, switches, toggles, levers, or capacitive buttons, among others. Other input devices may be contemplated. The buttons64may thus be programmable based on the dimensions and intended surface treatment agent thickness for a given shaft20.

A visual indicator66may also be provided. The visual indicator66may be one or more lights or a display screen. The visual indicator66may be operable to display a status of a delivery procedure of surface treatment agent42, for instance by displaying different message or light patterns/sequences based on an ongoing procedure, a “ready” status for a next procedure, or an “error” status indicative of an inability for the surface treatment agent42to be delivered. In the case of a display screen, text may be displayed to indicate, for instance, a type of error (e.g., a lack of surface treatment agent42in the receptacle). In some cases, an auditory indicator may additionally or alternatively be provided and be operable to signal various events of a delivery procedure of surface treatment agent42. The visual indicator66and/or auditory indicator may be operatively coupled to the timer70, for instance to alert a user of a remaining time period for a given delivery procedure of surface treatment agent42. In some cases, the timer70(or an additional timer) may be integrated into the handle62.

Various fluid pumps74may be contemplated. For instance, an electric fluid pump74, receiving power from the power supply76. may be operable to displace the surface treatment agent42from the receptacle68to the applicator60, with its activation controlled by the input device64, timer70and/or flow meter72. In other cases, the receptacle68may include a main receptacle storing a main supply of surface treatment agent42and a smaller receptacle that may be filled with the predetermined quantity of surface treatment agent42to be displaced towards the applicator60. In such cases, the fluid pump74, when activated, may displace the entire quantity of surface treatment agent42from the smaller receptacle68in order to deliver the predetermined quantity of surface treatment agent42to the applicator60. In such cases, an automatic fluid pump74may be used (e.g., an electric fluid pump74). Alternatively, a manual fluid pump74may be used, for instance a syringe-like device or a foot-activated pump for evacuating the surface treatment agent42from the smaller receptacle. Other fluid pump types and delivery means may be contemplated.

According to the present disclosure, there is taught an exemplary method for treating an inner surface28of a hollow engine shaft20of an aircraft engine10. An elongated rod46is engaged inside the hollow engine shaft20, the elongated rod46having a distal end50carrying an applicator60. A predetermined quantity of a surface treatment agent42is directed through an inner passage52of the elongated rod46towards the distal end50. The predetermined quantity of the surface treatment agent42is released from an outlet58of the inner passage52of the elongated rod46inside the hollow engine shaft20. The predetermined quantity of the surface treatment agent42is spread along the inner surface28of the hollow engine shaft20with the applicator60.

It can be appreciated that at least some embodiments have a surface treatment device with an elongated rod having an inner passage passing therethrough to deliver a predetermined quantity of a coating liquid to an applicator at a distal end thereof, thereby allowing for improved uniformity and repeatability in applying coating liquids/paint to the inner surfaces of hollow engine shafts.

In the present disclosure, when a specific numerical value is provided (e.g. as a maximum, minimum or range of values), it is to be understood that this value or these ranges of values may be varied, for example due to applicable manufacturing tolerances, material selection, etc. As such, any maximum value, minimum value and/or ranges of values provided herein (such as, for example only, the shaft having an axial length ranging from 20 to 80 inches), include(s) all values falling within the applicable manufacturing tolerances. Accordingly, in certain instances, these values may be varied by ±5%. In other implementations, these values may vary by as much as ±10%. A person of ordinary skill in the art will understand that such variances in the values provided herein may be possible without departing from the intended scope of the present disclosure, and will appreciate for example that the values may be influenced by the particular manufacturing methods and materials used to implement the claimed technology.