Office Action 1: Notice of Allowance (2025-04-15)

CLAIMS:
WHAT IS CLAIMED IS:
1.A method, comprising: measuring a first rotational speed of a first element of a sprag clutch of a rotorcraft; measuring a second rotational speed of a second element of the sprag clutch; determining if the sprag clutch is in an overrunning condition, wherein the determining is based on the first rotational speed and the second rotational speed; generating an estimation of an instantaneous wear rate of the sprag clutch, wherein the estimation of the instantaneous wear rate is generated based on the first rotational speed and the second rotational speed; and displaying an indication of the estimation of the instantaneous wear rate of the sprag clutch.
2.The method of claim 1 further comprising: generating an estimation of an accumulated wear of the sprag clutch, wherein the estimation of the accumulated wear is based on the estimation of the instantaneous wear rate; and displaying an indication of the estimation of the accumulated wear of the sprag clutch.
3\. The method of claim 2, wherein the indication of the estimation of the accumulated wear of the sprag clutch comprises an indication of the used life of the sprag clutch, wherein the indication of the used life of the sprag clutch is based on the estimation of the accumulated wear of the sprag clutch.
4\. The method of claim 1 further comprising determining a wear range of a plurality of wear ranges that corresponds to the estimation of the instantaneous wear rate, wherein the indication of the estimation of the instantaneous wear rate is based on the determined wear range.
5\. The method of claim 1, wherein generating an estimation of the instantaneous wear rate of the sprag clutch is based on a pressure-velocity factor, in which the pressure-velocity factor is a non-linear function of the first rotational speed and the second rotational speed.
6\. The method of claim 1, wherein generating an estimation of the instantaneous wear rate of the sprag clutch is based on a ratio between lubricant film thickness and surface roughness within the sprag clutch.
7\. The method of claim 6, wherein the surface roughness is based on a previously generated estimation of the instantaneous wear rate of the sprag clutch.
8\. The method of claim 1, wherein the sprag clutch mechanically couples two engines of the rotorcraft.
9.A clutch wear monitoring system, comprising: a first sensor operable to measure a first rotational speed of a first element of a clutch and generate a first sensor signal associated with the first rotational speed; a second sensor operable to measure a second rotational speed of a second element of the clutch and generate a second sensor signal associated with the second rotational speed; a controller configured to: receive the first sensor signal from the first sensor; receive the second sensor signal from the second sensor; determine an overrunning condition of the clutch based on the first sensor signal and the second sensor signal; determine a surface wear rate for the clutch based on the overrunning condition, the first sensor signal, and the second sensor signal; and generate a wear signal, wherein the wear signal is associated with the surface wear rate; and a display panel configured to receive the wear signal from the controller and display an indication of the surface wear rate based on the wear signal.
10\. The clutch wear monitoring system of claim 9, wherein the clutch is a sprag clutch.
11\. The clutch wear monitoring system of claim 9, wherein the controller is further configured to determine a total amount of surface wear and generate a total wear signal associated with the total amount of surface wear.
12\. The clutch wear monitoring system of claim 11, wherein the display panel is further configured to receive the wear total signal from the controller and display an indication of the total amount of surface wear based on the total wear signal.
13\. The clutch wear monitoring system of claim 12, wherein the display panel is configured to provide an alert when the total amount of surface wear reaches a threshold value.
14\. The clutch wear monitoring system of claim 9, wherein the display panel is configured to display a first indication when the surface wear rate is within a first range of values and is configured to display a second indication when the surface wear rate is within a second range of values, wherein the first indication is visually distinguished from the second indication.
15\. The clutch wear monitoring system of claim 14, wherein the display panel is configured to provide an alert when the surface wear rate is within a third range of values.
16.A device, comprising: a processor; and a non-transitory computer-readable storage medium storing a program to be executed by the processor, the program comprising instructions for: monitoring an inner element speed of an inner element of a sprag clutch; monitoring an outer element speed of an outer element of the sprag clutch; determining a pressure-velocity parameter for the sprag clutch, wherein the pressure-velocity parameter is based on the inner element speed and the outer element speed; determining a wear rate for the inner element of the sprag clutch, wherein the wear rate is based on the pressure-velocity parameter; and providing an indication of the wear rate on an instrument panel.
17\. The device of claim 16, wherein the pressure-velocity parameter depends on a difference between the inner element speed and the outer element speed.
18\. The device of claim 16, wherein the program comprises instructions for integrating the wear rate to determine an accumulated wear.
19\. The device of claim 16, wherein the processor is a flight control computer (FCC) of a fly-by-wire (FBW) system of a rotorcraft.
20\. The device of claim 19, wherein the program comprises instructions for controlling the flight of the rotorcraft based on the wear rate.

OFFICE ACTION:
DETAILED ACTION
Notice of Pre-AIA  or AIA  Status
1.	The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Information Disclosure Statement
2.	The information disclosure statement (IDS) submitted on 7/12/2024 is in compliance with the provisions of 37 CFR 1.97.  Accordingly, the information disclosure statement is being considered by the examiner.
Allowable Subject Matter
3.	Claims 1-20 are allowed.
The following is an examiner’s statement of reasons for allowance:
Jensen et al (US 20030183473 A1) teaches An RPM-responsive sprag overrunning clutch which includes a hub adapted to be attached to a drive shaft, a ring gear surrounding said hub and spaced therefrom, and a plurality of sprags positioned between said hub and ring gear. An actuator mechanism secured to the hub which includes a pair of movable segments and a pair of rollers which are free to move radially of said ring gear under the influence of centrifugal force as the clutch is rotated. Said movable segments being connected to an annular plate which is pinned to each of said sprags such that circumferential movement of the movable segments is transmitted to said sprags to shift them into or out of wedging relationship between the hub and ring gear. (Abstract)
Belhabib et al (EP 3913348 A1) teaches a method for detecting wear before failure of a freewheel of a mechanical system of a rotary wing aircraft i.e. helicopter, in a power plant by determining an oscillation measurement of a monitoring parameter within an upstream or downstream mechanical power transmission chain, determining a value of at least one parameter dynamic characteristic of the oscillation measurement or of a transform of the oscillation measurement in a frequency reference, and the generation of an alarm when said value of said dynamic parameter reaches at least one wear threshold.
Hale e al (US 10259572 B2) teaches A method and apparatus for determining failure diagnosis of drive systems of rotorcrafts through measuring the spectral characteristics of rotational oscillations and torsional oscillations and steady windup of a drive shaft. Mechanical anomalies of the drive system will alter the spectral characteristics of rotational oscillations and torsional oscillations and steady windup as detected by a pair of variable reluctance sensors in conjunction with a radial grating mounted on the drive shaft.
Regarding claims 1 & 9 the cited pertinent art does not anticipate nor render obvious  receiving a first sensor (rotational speed) signal from the first sensor; receiving a second sensor (rotational speed)  signal from the second sensor; determine an overrunning condition of a clutch based on the first sensor signal and the second sensor signal; determine a surface wear rate for the clutch based on the overrunning condition, the first sensor signal, and the second sensor signal; and generate a wear signal, wherein the wear signal is associated with the surface wear rate; and a display panel configured to receive the wear signal from the controller and display an indication of the surface wear rate based on the wear signal.
Regarding claim 16, the cited pertinent art does not anticipate nor render obvious a clutch wear monitoring system comprising determining a pressure-velocity parameter for a sprag clutch, wherein the pressure-velocity parameter is based on an inner element speed and an outer element speed; determining a wear rate for the inner element of the sprag clutch, wherein the wear rate is based on the pressure-velocity parameter; and providing an indication of the wear rate on an instrument panel.
Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee.  Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.”
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 11731779 B2 Drivetrain for an aircraft including gearbox with coaxial input and output shafts
KR 102205546 B1 real time monitoring apparatus and method for manual clutch of vehicle
US 10793284 B2 Multimode clutch assemblies for rotorcraft
US 10173787 B1 Rotor speed indication systems for rotorcraft



CITED REFERENCE SUMMARIES: Ref US11731779B2: Claims:
A drivetrain for an aircraft, the drivetrain comprising: an input shaft; a first electric motor coupled to the input shaft via a first sprag clutch; a planetary gear set coupled to the input shaft; a mast coupled to the planetary gear set, wherein the input shaft and the mast are coaxially aligned; rotor blades coupled to the mast to rotate with the mast; and a control tube coupled to the rotor blades and extending inside of the input shaft, the first electric motor, the planetary gear set, and the mast, wherein axial movement of the control tube changes a pitch of the rotor blades.
a first electric motor coupled to the input shaft via a first sprag clutch;
a planetary gear set coupled to the input shaft;
a mast coupled to the planetary gear set, wherein the input shaft and the mast are coaxially aligned;
rotor blades coupled to the mast to rotate with the mast; and
a control tube coupled to the rotor blades and extending inside of the input shaft, the first electric motor, the planetary gear set, and the mast, wherein axial movement of the control tube changes a pitch of the rotor blades.
The drivetrain of claim 1 , further comprising a second electric motor coupled to the input shaft via a second sprag clutch.
The drivetrain of claim 1 , wherein the planetary gear set comprises a gear ratio that reduces a rotational speed of the mast relative to the input shaft.
The drivetrain of claim 1 , wherein the first sprag clutch is a packed-grease sprag clutch.
A drivetrain for an aircraft, the drivetrain comprising: a gearbox having an input shaft and a mast coaxially aligned with the input shaft; a plurality of electric motors coupled to the input shaft, wherein each electric motor of the plurality of electric motors is coupled to the input shaft via a sprag clutch, rotor blades coupled to the mast to rotate with the mast; and a control tube coupled to the rotor blades and extending inside of the input shaft, the plurality of electric motors, the gearbox, and the mast, wherein axial movement of the control tube changes a pitch of the rotor blades.
a gearbox having an input shaft and a mast coaxially aligned with the input shaft;
a plurality of electric motors coupled to the input shaft, wherein each electric motor of the plurality of electric motors is coupled to the input shaft via a sprag clutch,
a control tube coupled to the rotor blades and extending inside of the input shaft, the plurality of electric motors, the gearbox, and the mast, wherein axial movement of the control tube changes a pitch of the rotor blades.
The drivetrain of claim 5 , wherein the input shaft is coupled to the mast via a planetary gear set.
The drivetrain of claim 6 , wherein the planetary gear set comprises a gear ratio that reduces a rotational speed of the mast relative to the input shaft.
The drivetrain of claim 5 , wherein each sprag clutch is a packed-grease sprag clutch.
A rotorcraft comprising: a plurality of fan assemblies, each fan assembly of the plurality of fan assemblies comprising a drivetrain, the drivetrain comprising: a gearbox having an input shaft and a mast coaxially aligned with the input shaft; a plurality of electric motors coupled to the input shaft, wherein each electric motor of the plurality of electric motors is coupled to the input shaft via a sprag clutch; rotor blades coupled to the mast to rotate with the mast; and a control tube coupled to the rotor blades and extending inside the input shaft, the first electric motor, the gearbox, and the mast, wherein axial movement of the control tube changes a pitch of the rotor blades.
a plurality of fan assemblies, each fan assembly of the plurality of fan assemblies comprising a drivetrain, the drivetrain comprising:
a plurality of electric motors coupled to the input shaft, wherein each electric motor of the plurality of electric motors is coupled to the input shaft via a sprag clutch;
a control tube coupled to the rotor blades and extending inside the input shaft, the first electric motor, the gearbox, and the mast, wherein axial movement of the control tube changes a pitch of the rotor blades.
The rotorcraft of claim 9 , wherein the input shaft is coupled to the mast via a planetary gear set.
The rotorcraft of claim 10 , wherein the planetary gear set comprises a gear ratio that reduces a rotational speed of the mast relative to the input shaft.
The rotorcraft of claim 9 , wherein the sprag clutches are packed-grease sprag clutches.
The rotorcraft of claim 9 , wherein one or more of the plurality of fan assemblies are ducted fan assemblies.
The rotorcraft of claim 9 , wherein the rotorcraft is a tiltrotor aircraft and the plurality fan assemblies rotate between an airplane mode and a helicopter mode.
The rotorcraft of claim 9 , wherein the plurality of electric motors are axial flux motors.
The rotorcraft of claim 9 , wherein the each fan assembly is a ducted fan comprising: a duct surrounding the rotor blades; a housing centrally located with the duct, wherein the housing contains the plurality of electric motors.
a duct surrounding the rotor blades;
a housing centrally located with the duct, wherein the housing contains the plurality of electric motors.
The rotorcraft of claim 16 , wherein the plurality of electric motors are axial flux motors.
The rotorcraft of claim 16 , wherein the drive train does not comprise an engine.
The rotorcraft of claim 16 , wherein the ducted fan is mounted on a spindle and is rotatable relative to a fuselage of the rotorcraft between an airplane mode and a helicopter mode.
The rotorcraft of claim 19 , wherein the plurality of electric motors are axial flux motors.
Ref US10793284B2: Claims:
A multimode clutch assembly for a rotorcraft, the multimode clutch assembly comprising: a freewheeling unit having an input race and an output race, the freewheeling unit having a driving mode in which torque applied to the input race is transferred to the output race and an overrunning mode in which torque applied to the output race is not transferred to the input race; a bypass assembly having an engaged position in which the bypass assembly couples the input and output races of the freewheeling unit and a disengaged position in which the bypass assembly does not couple the input and output races of the freewheeling unit; and a four port, three position hydraulic control valve having an engagement configuration supplying an engagement pressure signal to shift the bypass assembly from the disengaged position to the engaged position and a disengagement configuration supplying a disengagement pressure signal to shift the bypass assembly from the engaged position to the disengaged position; wherein, in the disengaged position of the bypass assembly, the overrunning mode of the freewheeling unit is enabled such that the multimode clutch assembly is configured for unidirectional torque transfer from the input race to the output race; and wherein, in the engaged position of the bypass assembly, the overrunning mode of the freewheeling unit is disabled such that the multimode clutch assembly is configured for bidirectional torque transfer between the input and output races.
a freewheeling unit having an input race and an output race, the freewheeling unit having a driving mode in which torque applied to the input race is transferred to the output race and an overrunning mode in which torque applied to the output race is not transferred to the input race;
a bypass assembly having an engaged position in which the bypass assembly couples the input and output races of the freewheeling unit and a disengaged position in which the bypass assembly does not couple the input and output races of the freewheeling unit; and
a four port, three position hydraulic control valve having an engagement configuration supplying an engagement pressure signal to shift the bypass assembly from the disengaged position to the engaged position and a disengagement configuration supplying a disengagement pressure signal to shift the bypass assembly from the engaged position to the disengaged position;
wherein, in the disengaged position of the bypass assembly, the overrunning mode of the freewheeling unit is enabled such that the multimode clutch assembly is configured for unidirectional torque transfer from the input race to the output race; and
wherein, in the engaged position of the bypass assembly, the overrunning mode of the freewheeling unit is disabled such that the multimode clutch assembly is configured for bidirectional torque transfer between the input and output races.
The multimode clutch assembly as recited in claim 1 wherein, in the engaged position of the bypass assembly, the hydraulic control valve maintains the engagement pressure signal on the bypass assembly in an unenergized state of the hydraulic control valve.
The multimode clutch assembly as recited in claim 1 wherein, in the engaged position of the bypass assembly, the hydraulic control valve maintains the engagement pressure signal on the bypass assembly in a loss of supply pressure state of the hydraulic control valve.
The multimode clutch assembly as recited in claim 1 wherein, in the engaged position of the bypass assembly, the hydraulic control valve maintains the engagement pressure signal on the bypass assembly in a default configuration of the hydraulic control valve.
The multimode clutch assembly as recited in claim 4 wherein the hydraulic control valve is operated from the default configuration to the engagement configuration or the disengagement configuration responsive to an electric signal.
The multimode clutch assembly as recited in claim 4 wherein the hydraulic control valve is operated from the engagement configuration or the disengagement configuration to the default configuration responsive to a mechanical signal.
The multimode clutch assembly as recited in claim 1 further comprising a lubrication oil circuit in fluid communication with the hydraulic control valve, the lubrication oil circuit providing pressurized lubrication oil to the hydraulic control valve.
A powertrain for a rotorcraft, the powertrain comprising: a main drive system including a main engine coupled to a main rotor gearbox; a secondary engine; and a multimode clutch assembly positioned between the main drive system and the secondary engine, the multimode clutch assembly including: a freewheeling unit having an input race coupled to the main drive system and an output race coupled to the secondary engine, the freewheeling unit having a driving mode in which torque applied to the input race is transferred to the output race and an overrunning mode in which torque applied to the output race is not transferred to the input race; a bypass assembly having an engaged position in which the bypass assembly couples the input and output races of the freewheeling unit and a disengaged position in which the bypass assembly does not couple the input and output races of the freewheeling unit; and a hydraulic actuator having an engagement configuration supplying an engagement pressure signal to shift the bypass assembly from the disengaged position to the engaged position and a disengagement configuration supplying a disengagement pressure signal to shift the bypass assembly from the engaged position to the disengaged position; wherein, in the disengaged position of the bypass assembly, the overrunning mode of the freewheeling unit is enabled such that the multimode clutch assembly is configured for unidirectional torque transfer from the input race to the output race; and wherein, in the engaged position of the bypass assembly, the overrunning mode of the freewheeling unit is disabled such that the multimode clutch assembly is configured for bidirectional torque transfer between the input and output races.
a main drive system including a main engine coupled to a main rotor gearbox;
a secondary engine; and
a multimode clutch assembly positioned between the main drive system and the secondary engine, the multimode clutch assembly including:
a freewheeling unit having an input race coupled to the main drive system and an output race coupled to the secondary engine, the freewheeling unit having a driving mode in which torque applied to the input race is transferred to the output race and an overrunning mode in which torque applied to the output race is not transferred to the input race;
a hydraulic actuator having an engagement configuration supplying an engagement pressure signal to shift the bypass assembly from the disengaged position to the engaged position and a disengagement configuration supplying a disengagement pressure signal to shift the bypass assembly from the engaged position to the disengaged position;
The powertrain as recited in claim 8 wherein the main engine further comprises a first gas turbine engine and wherein the secondary engine further comprises a second gas turbine engine.
The powertrain as recited in claim 8 wherein the main engine further comprises a gas turbine engine and wherein the secondary engine further comprises an electric motor.
The powertrain as recited in claim 8 wherein the hydraulic actuator further comprises a hydraulic control valve.
The powertrain as recited in claim 11 wherein the hydraulic control valve further comprises a four port, three position hydraulic control valve.
The powertrain as recited in claim 11 wherein, in the engaged position of the bypass assembly, the hydraulic control valve maintains the engagement pressure signal on the bypass assembly in an unenergized state of the hydraulic control valve, in a loss of supply pressure state of the hydraulic control valve and in a default configuration of the hydraulic control valve.
A rotorcraft comprising: a main drive system including a main engine coupled to a main rotor gearbox; a main rotor coupled to the main rotor gearbox and rotatable thereby; a secondary engine; and a multimode clutch assembly positioned between the main drive system and the secondary engine, the multimode clutch assembly including: a freewheeling unit having an input race coupled to the main drive system and an output race coupled to the secondary engine, the freewheeling unit having a driving mode in which torque applied to the input race is transferred to the output race and an overrunning mode in which torque applied to the output race is not transferred to the input race; a bypass assembly having an engaged position in which the bypass assembly couples the input and output races of the freewheeling unit and a disengaged position in which the bypass assembly does not couple the input and output races of the freewheeling unit; and a hydraulic actuator having an engagement configuration supplying an engagement pressure signal to shift the bypass assembly from the disengaged position to the engaged position and a disengagement configuration supplying a disengagement pressure signal to shift the bypass assembly from the engaged position to the disengaged position; wherein, in the disengaged position of the bypass assembly, the overrunning mode of the freewheeling unit is enabled such that the multimode clutch assembly is configured for unidirectional torque transfer from the input race to the output race; and wherein, in the engaged position of the bypass assembly, the overrunning mode of the freewheeling unit is disabled such that the multimode clutch assembly is configured for bidirectional torque transfer between the input and output races.
a main rotor coupled to the main rotor gearbox and rotatable thereby;
The rotorcraft as recited in claim 14 wherein, in a preflight configuration, the bypass assembly is in the disengaged position, the main engine is not operating and the secondary engine provides power to at least one rotorcraft accessory.
The rotorcraft as recited in claim 14 wherein, in an enhanced power configuration, the bypass assembly is in the engaged position, the main engine provides power to the main rotor gearbox and the secondary engine provides power to at least one rotorcraft accessory and to the main drive system through the multimode clutch assembly.
The rotorcraft as recited in claim 14 wherein, in a high efficiency configuration, the bypass assembly is in the engaged position, the secondary engine is in standby mode, the main engine provides power to the main rotor gearbox and to at least one rotorcraft accessory through the multimode clutch assembly.
The rotorcraft as recited in claim 14 wherein, in an enhanced autorotation configuration, the bypass assembly is in the engaged position, the main engine is not operating and the secondary engine provides power to the main drive system through the multimode clutch assembly.
Ref US10259572B2: Claims:
A system for detecting torsional anomalies of an aircraft during a failure, the aircraft having a first drive shaft and a second drive shaft, the system comprising: a grating, having; a plurality of teeth extending from the grating, the grating coupled to a first interconnection between the first drive shaft and the second drive shaft; a support bracket in close proximity to the first interconnection and positioned about the grating; a first sensor mounted on the support bracket; a second sensor mounted on the support bracket; and a processor comprising; a lookup table comprising; a plurality of spectral data of predetermined faults; the processor for comparing a spectral analysis of an output of the first sensor and second sensor to the lookup table; wherein the first sensor and second sensor are configured to detect the teeth of the grating.
a grating, having; a plurality of teeth extending from the grating, the grating coupled to a first interconnection between the first drive shaft and the second drive shaft;
a plurality of teeth extending from the grating, the grating coupled to a first interconnection between the first drive shaft and the second drive shaft;
a support bracket in close proximity to the first interconnection and positioned about the grating;
a first sensor mounted on the support bracket;
a second sensor mounted on the support bracket; and
a processor comprising; a lookup table comprising; a plurality of spectral data of predetermined faults;
a lookup table comprising; a plurality of spectral data of predetermined faults;
a plurality of spectral data of predetermined faults;
the processor for comparing a spectral analysis of an output of the first sensor and second sensor to the lookup table;
wherein the first sensor and second sensor are configured to detect the teeth of the grating.
The system according to claim 1 , wherein the second sensor is rotated 180 degrees relative to the first sensor.
The system according to claim 1 , wherein the first sensor is a variable reluctance sensor.
The system according to claim 1 , wherein the grating comprises: a center aperture; wherein the center aperture is configured to allow the first interconnection to pass through the grating.
a center aperture;
wherein the center aperture is configured to allow the first interconnection to pass through the grating.
The system according to claim 1 , further comprising: a display; wherein the processor provides a real-time indication of torque values of the first drive shaft on the display.
wherein the processor provides a real-time indication of torque values of the first drive shaft on the display.
The system according to claim 1 , wherein the plurality of teeth around the grating are equally spaced around the grating.
A system for detecting torsional anomalies of an aircraft during a failure, the aircraft having a first drive shaft and a second drive shaft, the system comprising: a first sensor assembly having; a forward support bracket; a first forward sensor; a second forward sensor; and a first grating, having; a plurality of teeth radially extending from the first grating; the first and second forward sensors being mounted on the forward support bracket and position
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