Patent Description:
Certain types of phonic wheels can be used to provide information regarding the phase of rotation of the propeller, usually by removing one of the markers, creating a "missing tooth" which can be detected, or by adding an additional marker which is distinguishable from the other markers. However, existing approaches can lead to inaccurate measurements.

A prior art phonic wheel having the features of the preamble of claim <NUM> is disclosed in <CIT>. <CIT> also discloses a prior art phonic wheel.

In accordance with an aspect of the present invention, there is provided a phonic wheel for use in a gas turbine engine, as claimed in claim <NUM>.

In some embodiments, the at least one second position marker having a second physical configuration different from the first physical configuration comprises the at least one second position marker having a height greater than that the first plurality of position markers.

In some embodiments, the at least one second position marker having a second physical configuration different from the first physical configuration comprises the at least one second position marker having a width greater than that of the first plurality of position markers.

In some embodiments, the at least one second position marker having a second physical configuration different from the first physical configuration comprises the at least one second position marker having a shape different from that of the first plurality of position markers.

In some embodiments, the at least one second position marker having a second physical configuration different from the first physical configuration comprises the at least one second position marker being fabricated from a material different than that from which the first plurality of position markers are fabricated.

In some embodiments, the at least one second position marker is positioned substantially equidistant between the two adjacent ones of the first plurality of position markers.

In some embodiments, the at least one second position marker is positioned closer to a particular one of the two adjacent ones of the first plurality of position markers than to a second one thereof.

In some embodiments, the circular disk has first and second opposing faces and defines a root surface that extends between and circumscribes the first and second faces, and the at least one second position marker is disposed at a <NUM>° angle relative to the first plurality of position markers.

In accordance with another aspect of the present invention, there is provided a phonic wheel system for a gas turbine engine, as claimed in claim <NUM>.

In some embodiments, the at least one second position marker having a second physical configuration different from the first physical configuration comprises the at least one second position marker having at least one of a height, a width, and a shape different than that the first plurality of projections.

In some embodiments, the at least one sensor is configured to sense passage of the first plurality of position markers and the at least one second position marker as the phonic wheel rotates. In some embodiments, the at least one sensor is configured to sense a relative passage of the first plurality of position markers and the at least one second position marker as the at least one sensor rotates.

In accordance with a still further aspect of the present invention, there is provided a method for sensing a phonic wheel in a gas turbine engine, as claimed in claim <NUM>. In some embodiments, the phonic wheel defines a root surface that extends between and circumscribes first and second faces, and the at least one second position marker is disposed on the root surface at a <NUM>° angle relative to the first plurality of position markers.

In some embodiments, the at least one second signal pulse is produced responsive to detecting the at least one second position marker having the second physical configuration comprising at least one of a second height, second width, and/or a second shape different from the first physical configuration comprising a corresponding at least one of a first height, a first width, and/or a first shape.

In some embodiments, the at least one second signal pulse is produced responsive to detecting the at least one second position marker fabricated from a second material different than a first material from which the first plurality of position markers are fabricated.

Features of the systems, devices, and methods described herein may be used in various combinations, in accordance with the embodiments described herein.

<FIG> depicts a gas turbine engine <NUM> of a type typically provided for use in subsonic flight. The engine <NUM> comprises an inlet <NUM> through which ambient air is propelled, a compressor section <NUM> for pressurizing the air, a combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section <NUM> for extracting energy from the combustion gases.

The turbine section <NUM> comprises a compressor turbine <NUM>, which drives the compressor assembly and accessories, and at least one power or free turbine <NUM>, which is independent from the compressor turbine <NUM> and rotatingly drives a rotor shaft <NUM> about a propeller shaft axis 'A' through a reduction gearbox <NUM>. Hot gases may then be evacuated through exhaust stubs <NUM>. The gas generator of the engine <NUM> comprises the compressor section <NUM>, the combustor <NUM>, and the turbine section <NUM>.

A rotor, in the form of a propeller <NUM> through which ambient air is propelled, is hosted in a propeller hub <NUM>. The rotor may, for example, comprise the propeller <NUM> of a fixed-wing aircraft, or a main (or tail) rotor of a rotary-wing aircraft such as a helicopter. The propeller <NUM> may comprise a plurality of circumferentially-arranged blades connected to a hub by any suitable means and extending radially therefrom. The blades are also each rotatable about their own radial axes through a plurality of blade angles, which can be changed to achieve modes of operation, such as feather, full reverse, and forward thrust.

With reference to <FIG>, a system <NUM> for sensing a phonic wheel <NUM> will now be described. In some embodiments, the system <NUM> provides for detection and measurement of rotational velocity of one or more rotating elements of the engine <NUM>, for example the propeller <NUM>, and of other propeller-related parameters, for instance propeller blade angle. The system <NUM> may interface to existing mechanical interfaces of typical propeller systems to provide a digital detection for electronic determination of the propeller blade angle. It should be noted that although the present disclosure focuses on the use of the system <NUM> and the phonic wheel <NUM> in gas-turbine engines, similar techniques can be applied to other types of engines, including electric engines.

The system <NUM> comprises an annular member <NUM> and one or more sensors <NUM> positioned proximate the annular member <NUM>. Annular member <NUM> (referred to herein as a phonic wheel) has a plurality of position markers <NUM> provided thereon for detection by sensor <NUM>. In some embodiments, the phonic wheel <NUM> is mounted for rotation with propeller <NUM> and to move axially with adjustment of the blade angle of the blades of the propeller <NUM>, and the sensor <NUM> is fixedly mounted to a static portion of the engine <NUM> and/or the propeller <NUM>. In other embodiments, the sensor <NUM> is mounted for rotation with propeller <NUM> and to move axially with adjustment of the blade angle of the blades of the propeller <NUM>, and the phonic wheel <NUM> is fixedly mounted to a static portion of the engine <NUM> and/or the propeller <NUM>.

The system <NUM> also includes a controller <NUM> communicatively coupled to the sensor <NUM>. The sensor <NUM> is configured for producing a signal, for instance an electrical or optical signal, which is transmitted to or otherwise received by the controller <NUM>, for example via a detection unit <NUM> thereof. In some embodiments, the sensor <NUM> produces a series of signal pulses in response to detecting the presence of a position marker <NUM> in a sensing zone of the sensor <NUM>. For example, the sensor <NUM> operates on detecting changes in magnetic flux, and has a sensing zone which encompasses a circular or rectangular area or volume in front of the sensor <NUM>. When a position marker <NUM> is present in the zone, or passes through the zone during rotation of the phonic wheel <NUM>, the magnetic flux in the sensing zone is varied by the presence of the position marker <NUM>, and the sensor <NUM> can produce a signal pulse, which forms part of the signal.

In the example illustrated in <FIG>, a side view of a portion of phonic wheel <NUM> and sensor <NUM> is shown. The sensor <NUM> is mounted to a flange <NUM> of a housing of the reduction gearbox <NUM>, so as to be positioned adjacent the plurality of position markers <NUM>. In some embodiments, the sensor <NUM> is secured to the propeller <NUM> so as to extend away from the flange <NUM> and towards the position markers <NUM> along a radial direction, identified in <FIG> as direction 'R'. Sensor <NUM> and flange <NUM> may be fixedly mounted, for example to the housing of the reduction gearbox <NUM>, or to any other static element of the engine <NUM>, as appropriate.

In some embodiments, a single sensor <NUM> is mounted in close proximity to the phonic wheel <NUM> and the position markers <NUM>. In some other embodiments, in order to provide redundancy, one or more additional sensors, which may be similar to the sensor <NUM>, are provided. For example, an additional sensor <NUM> may be mounted in a diametrically opposite relationship relative to the position markers <NUM>, which extend away from the phonic wheel <NUM> and towards the sensor(s) <NUM>. In yet another embodiment, several position markers <NUM> may be spaced equiangularly about the perimeter of the phonic wheel <NUM>. Other embodiments may apply.

With reference to <FIG>, in some embodiments the phonic wheel <NUM> is embodied as a circular disk which rotates as part of the engine <NUM>, for example with the output shaft <NUM> or with the propeller <NUM>. The phonic wheel <NUM> comprises opposing faces <NUM> and defines a root surface <NUM> which extends between the opposing faces <NUM> and circumscribes them. Put differently, the root surface <NUM> of the phonic wheel <NUM> is the outer periphery of the circular disk which spans between the two opposing faces <NUM>. In these embodiments, the position markers <NUM> can take the form of projections which extend from the root surface <NUM>, as illustrated in <FIG> and discussed in greater detail hereinbelow.

With continued reference to <FIG>, the phonic wheel <NUM> is supported for rotation with the propeller <NUM>, which rotates about the longitudinal axis 'A'. The phonic wheel <NUM> is also supported for longitudinal sliding movement along the axis A, e.g. by support members, such as a series of circumferentially spaced beta feedback rods <NUM> that extend along the longitudinal axis 'A'. A compression spring <NUM> surrounds an end portion of each rod <NUM>.

As depicted in <FIG>, the propeller <NUM> comprises a plurality of angularly arranged blades <NUM>, each of which is rotatable about a radially-extending axis 'R' through a plurality of adjustable blade angles, the blade angle being the angle between the chord line (i.e. a line drawn between the leading and trailing edges of the blade) of the propeller blade section and a plane perpendicular to the axis of propeller rotation. In some embodiments, the propeller <NUM> is a reversing propeller, capable of operating in a variety of modes of operation, including feather, full reverse, and forward thrust. Depending on the mode of operation, the blade angle may be positive or negative: the feather and forward thrust modes are associated with positive blade angles, and the full reverse mode is associated with negative blade angles.

With reference to <FIG>, different embodiments of the phonic wheel <NUM> are illustrated. As discussed hereinabove, the phonic wheel <NUM> comprises the position markers <NUM>, which can take the form of projections which extend from the root surface <NUM>. As the phonic wheel <NUM> rotates, varying portions thereof enter, pass through, and then exit the sensing zone of the sensor <NUM>. From the perspective of the sensor <NUM>, the phonic wheel moves along direction 'F' as the phonic wheel rotates.

In <FIG>, a top-view of a portion of the phonic wheel <NUM> is shown. In the illustrated embodiment, the position markers <NUM> include a plurality of projections <NUM> which are arranged along direction 'D', which is substantially transverse to the opposing faces <NUM>. Although only two projections <NUM> are illustrated in <FIG>, it should be understood that any suitable number of projections <NUM> may be present across the whole of the root surface <NUM>. The projections <NUM> can be substantially equally spaced from one another on the root surface <NUM>. In addition, the projections <NUM> are of substantially a common shape and size, for example having a common volumetric size.

The phonic wheel <NUM> also includes at least one supplementary projection <NUM> which is positioned between two adjacent ones of the projections <NUM>. In the embodiment depicted in <FIG>, the projection <NUM> is oriented along direction 'E', which is at an angle relative to direction 'D'. The angle between directions 'D' and 'E' can be any suitable value between <NUM>° and <NUM>°, for example <NUM>°, <NUM>°, <NUM>°, or any other value, as appropriate.

In some embodiments, the phonic wheel <NUM> includes only a single supplementary projection <NUM>; in other embodiments, the phonic wheel <NUM> can include two, three, four, or more supplementary projections <NUM>. In embodiments in which the phonic wheel <NUM> includes more than one supplementary projection <NUM>, the supplementary projections can be oriented along a common orientation or can be oriented along one or more different orientations. The projection <NUM> can be located at substantially a midpoint between two adjacent projections <NUM>, or can be located close to a particular one of two adjacent projections <NUM>.

The projection <NUM> is angled with respect to the projections <NUM>, and the change in magnetic flux caused by the presence of the projection <NUM> may be different than that caused by the presence of the projection <NUM>. For example, due to the shape of the sensing zone of the sensor <NUM>, the change in magnetic flux produced by the presence of the projection <NUM> may be less than the change in magnetic flux produced by the presence of one of the projections <NUM>. As a result, the signal pulse (referred to herein as a second signal pulse) produced in response to the sensor <NUM> detecting the presence of the projection <NUM> may be smaller, or less pronounced, than a corresponding signal pulse (referred to herein as a first signal pulse) produced in response to the sensor <NUM> detecting the presence of the projection <NUM>. The uneven nature of the first and second signal pulses can complicate signal processing of the signal produced by the sensor <NUM>, for example for the controller <NUM>, and can lead to inaccurate measurements.

In order to equalize the signal pulses produced by the sensor <NUM>, the projections <NUM> and the projection <NUM> are designed to have different physical configurations. That is to say, the projections <NUM> and the projection <NUM> can be of different shapes, different sizes, and/or made of different materials, so that the change in magnetic flux sensed by the sensor <NUM> and produced by the presence of the projection <NUM> in the sensing zone is substantially identical to the change in magnetic flux sensed by the sensor <NUM> and produced by the presence of any one of the projections <NUM>. In some embodiments, the projections <NUM>, <NUM> extend to form a tip, and it is a tip shape of the projections <NUM> which is shaped differently from the tip shape of the projections <NUM>.

For example, the projection <NUM> can have a dimension (e.g. a height, a width, and/or a length) that is greater than for the projections <NUM>, such that the volumetric size of the projection <NUM> is greater than that of the projections <NUM>. In some cases, the projections <NUM> can be machined to be smaller, thinner, shorter, and/or of a different shape than the projections <NUM>, and in some other cases, the projection <NUM> is formed to be taller, wider, longer, and/or of a different shape than the projections <NUM>. For example, the projection <NUM> can extend beyond a plane formed by one or both of the opposing faces <NUM>. Any other suitable differentiation in dimensions between the projections <NUM>, <NUM> is also considered.

When the projection <NUM> is angled with respect to the projections <NUM>, the sensor <NUM> may detect substantially the whole of one of the projections <NUM> when it enters the sensing zone of the sensor <NUM>, but only a portion of the projection <NUM> when it enters the sensing zone. By providing different volumetric sizes for the projections <NUM> and the projection <NUM>, whether as a result of different dimensions (e.g. heights, widths, and/or lengths), the portion of the projection <NUM> sensed by the sensor <NUM> in the sensing zone can be made comparable to that for the projections <NUM>. Thus, the second signal pulse produced by the sensor <NUM> in response to the presence of the projection <NUM> can be tuned to be substantially equal to that produced in response to the presence of one of the projections <NUM>.

It should be noted that, as used herein, the terms "equal" and "equalize" are understood to refer to substantial equivalence to within a particular tolerance or range. For example, if the projections <NUM> produce electrical signal pulses having an amplitude of approximately <NUM> Volt (V), an electrical signal pulse produced by the projection <NUM> can be considered equal if it has an amplitude within a window of <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or any other suitable tolerance, around <NUM> V. For instance, if the projection <NUM> produces an electrical signal pulse with an amplitude of <NUM> V, this can be considered equal to the electrical signal pulse produced by the projections <NUM>, and the magnetic flux response of the projections <NUM> and the projection <NUM> are said to be equalized.

Alternatively, or in addition, the shape of the projection <NUM>, or the material of which it is composed, can be different than that of the projections <NUM>. For instance, the projection <NUM> can be provided in a shape that increases the magnetic flux change observed by the sensor <NUM>, such as a different rectangular shape, a trapezoidal shape, a pyramidal shape, and the like. In another example, the projection <NUM> can be fabricated with a material which produces a greater change in magnetic flux. For instance, if the projections <NUM> and the projection <NUM> are similarly sized, but the projection <NUM> is angled <NUM>° with respect to the projections <NUM>, the projection <NUM> can be made of a material which induces twice as much change in magnetic flux as the material used for the projections <NUM>. Still other approaches are considered.

In <FIG>, the projection <NUM> is shown as being thicker than the projections <NUM>. With reference to <FIG>, the projection <NUM> is shown as being taller than the projections <NUM>. It should be noted that any combination of suitable changes to the projection <NUM>, or to the projections <NUM>, or both, can be employed in order to equalize the signal pulses produced by the sensor <NUM>. For example, the projection <NUM> can be both taller and wider than the projections <NUM>. In another example, the projection <NUM> can be wider and of a different material than the projections <NUM>. Still other combinations are considered.

In some embodiments, the dimensions of the projections <NUM> and/or the projection <NUM> is established iteratively, in order to produce projections <NUM>, <NUM> which result in substantially equal signal pulses, when sensed by the sensor <NUM>. The iterative process for determining the dimensions of the projections <NUM>, <NUM> can be performed with physical phonic wheels and/or using modelling tools. Similar techniques can be applied when the material used to make the projections <NUM> and/or the projection <NUM> is varied.

The signal pulses produced by the sensor <NUM>, which form part of the signal received by the controller <NUM>, can be used to determine various operating parameters of the engine <NUM> and/or of the propeller <NUM>. For example, the series of first signal pulses can be indicative of the speed of rotation of the engine <NUM> and/or the propeller <NUM>, and the second signal pulse can be indicative of a phase of the propeller <NUM>.

Although the preceding paragraphs focus on the use of the sensor <NUM> which detects changes in magnetic flux due to the presence of one of the projections <NUM>, <NUM> in the sensing zone of the sensor, it should be understood that other types of sensors are also considered. For instance, an optical sensor which detects reflectivity of light off of position markers <NUM> can be used, and in this case the projections <NUM> can have a physical configuration which increases the reflectivity of the projections <NUM>. In another example, an acoustic sensor which performs detection of position markers <NUM> using echoed sound waves can be used, and in this case the projections <NUM> can have a physical configuration which increases the degree to which incoming sound waves are reflected toward the acoustic sensor. Still other embodiments are considered.

In addition, the present disclosure focuses primarily on embodiments in which the position markers <NUM> are projections, it should be noted that the techniques described herein may also be applied to other types of position markers <NUM>. For instance, in some embodiments, the position markers <NUM> are embedded in the circular disk portion of the phonic wheel <NUM>, such that the phonic wheel <NUM> has a substantially smooth or uniform root surface <NUM>. For example, a position marker <NUM> can be a portion of the phonic wheel <NUM> which is made of a different material, or to which is applied a layer of a different material. The area of the different material can be varied in order to tune the pulses produced by the sensor <NUM>. Still other embodiments are considered.

With reference to <FIG>, there is illustrated a method for sensing a phonic wheel in an engine and/or of a propeller, for instance the phonic wheel <NUM>. At step <NUM>, a series of first signal pulses are produced via a sensor, for instance the sensor <NUM>, in response to detecting a first plurality of projections, for example the projections <NUM>. At step <NUM>, at least one second signal pulse is produced via the sensors <NUM> in response to detecting at least one second projection, for example the projection <NUM>, which has a physical configuration different from that of the first projections.

In embodiments where the projection <NUM> is located substantially equidistantly between adjacent projections <NUM>, the time between sensing a first projection <NUM> and sensing the projection <NUM> can be substantially equal to the time between sensing the projection <NUM> and a sensing a subsequent one of the projections <NUM>. In embodiments where the projection <NUM> is located closer to a particular one of the projections <NUM> than to a subsequent one of the projections <NUM>, the duration between detecting the particular projection <NUM> and the projection <NUM> may be shorter than the duration between detecting the projection <NUM> and the subsequent projection <NUM>.

Optionally, at steps <NUM> and <NUM>, a speed of the engine <NUM> and/or the propeller <NUM>, and/or a phase of the propeller <NUM> can be determined based on the series of first signal pulses and based on the at least one second signal pulse, respectively.

With reference to <FIG>, the method <NUM> may be implemented by a computing device <NUM>, comprising a processing unit <NUM> and a memory <NUM> which has stored therein computer-executable instructions <NUM>. For example, the controller <NUM> may be embodied as the computing device <NUM>.

The memory <NUM> may include a suitable combination of any type of computer memory that is located either internally or externally to device, for example random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like.

It should be noted that the computing device <NUM> may be implemented as part of a FADEC or other similar device, including electronic engine control (EEC), engine control unit (EUC), and the like. In addition, it should be noted that the method <NUM> and, more generally, the techniques described herein can be performed substantially in real-time, during operation of the engine <NUM>. For example, if the engine <NUM> is used as part of an aircraft, the monitoring of the engine <NUM> can be performed in real-time during a flight mission. The results of the monitoring can be reported to the operator and adjustments to the operational parameters of the engine <NUM> can also be performed in real-time.

The phonic wheel and related systems and methods described herein may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device <NUM>. Alternatively, the methods and systems described herein may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems described herein may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems described herein may also be considered to be implemented by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or more specifically the processing unit <NUM> of the computing device <NUM>, to operate in a specific and predefined manner to perform the functions described herein, for example those described in the method <NUM>.

The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the claims.

Claim 1:
A phonic wheel (<NUM>) for a gas turbine engine (<NUM>), the phonic wheel (<NUM>) comprising:
a circular disk;
a first plurality of position markers (<NUM>) disposed on the disk and oriented substantially parallel to an axis of rotation (A) of the circular disk, the first plurality of position markers (<NUM>) each having a first physical configuration and configured to produce a series of first signal pulses when detected within a sensing zone of at least one sensor (<NUM>); and
at least one second position marker (<NUM>) disposed on the disk between two adjacent first position markers (<NUM>) and oriented at an angle relative to the first plurality of position markers (<NUM>), the at least one second position marker (<NUM>) configured to produce a second signal pulse when detected within the sensing zone of the at least one sensor (<NUM>),
characterised in that:
the at least one second position marker (<NUM>) has a second physical configuration different from the first physical configuration such that the second signal pulse is substantially equalized with the first signal pulse.