Patent Description:
Preventative maintenance in actuation systemis becoming increasingly important in various fields, including, for example, aircraft technologies as airlines strive to increase operational efficiency. One way to achieve this goal is to have a predictive system available to anticipate failures before they occur. Currently, on-condition service results in unscheduled repairs with potential delays due to parts and maintenance crews being unavailable right away. On the other hand, predictive systems allow operators to make arrangements for repair (e.g., by obtaining parts and ensuring availabilities of maintenance crews) in advance and thus reduce time required to return an aircraft to service. Advanced planning can also reduce inventories for operator or service centers as parts can be ordered ahead of repair times. <CIT> relates to a method of monitoring a flap system, and a flap system. <CIT> relates to an integrated torque limiter/no-back device.

According to an aspect of the disclosure, a predictive system is provided in claim <NUM> and includes a torque-limiter comprising a ball-ramp mechanism, a sensor disposed to sense a condition of the torque-limiter, the condition comprising a distance between plates of the ball-ramp mechanism, and a processing system. The processing system is coupled to the sensor and configured to process readings of the sensor, to calculate whether the condition of the torque-limiter is indicative of degradation or failure incidents based on the readings being processed and to determine whether an action should be taken based on a calculation result. The processing system calculates that the condition of the torque-limiter is indicative of the degradation or failure incidents based on the condition exceeding a first threshold or reaching a second threshold, respectively.

In accordance with additional or alternative embodiments, the torque-limiter and the sensor are mounted in a housing.

In accordance with additional or alternative embodiments, the sensor includes at least one or more proximity sensors.

In accordance with additional or alternative embodiments, the at least one or more proximity sensors include at least one or more of an optical sensor, an electromagnetic sensor, a Hall Effect sensor, a linear variable differential transformer (LVDT) sensor and a capacitive sensor.

In accordance with additional or alternative embodiments, the processing system includes at least one or more of a controller and a prognostic maintenance computer.

In accordance with additional or alternative embodiments, the action includes arranging maintenance.

According to another example of the disclosure, a predictive system is provided for use with a ball-ramp mechanism. The ball-ramp mechanism includes a first plate to which an input shaft is coupled, a second plate to which an output shaft is coupled and a ball element which is disposable within complementary recesses in the first and second plates. The predictive system includes a sensor disposed to sense a distance between the first and second plates in a dimension defined along a longitudinal axis of the input and output shafts and a processing system. The processing system is coupled to the sensor and configured to process readings of the sensor, to calculate whether the distance between the first and second plates is indicative of degradation or failure incidents based on the readings being processed and to determine whether an action should be taken based on a calculation result.

As will be described below, a predictive system is provided and may be used with a torque-limiter or another suitable similar mechanism. In the case of the predictive system being used with a torque-limiter and in the case of the torque-limiter being provided as a ball-ramp mechanism, the predictive system includes a sensor that monitors changes in the available system torque over time using a springloaded ball-ramp mechanism. The sensor can be located at various points along a driveline, in a power drive unit or in an actuator. Under normal conditions, the ball-ramp mechanism allows torque to be passed from one shaft to another shaft without its plates moving relative to one another. However, if torque exceeds a predefined value, the balls of the ball-ramp mechanism will rise in the pockets of the plates and push the plates apart. In conventional applications, the ball-ramp mechanism will provide for a visual indication after an incident of the plates being pushed apart. This visual indication must be observed manually requiring time and, in some cases, the removal of surrounding paneling. In the predictive system, however, the sensor can continuously monitor relative plate movement and send signals that are indicative of relative plate movement to a processing system. The processing system can then determine whether the relative plate movement is greater than a predetermined threshold without exceeding overload limits while taking into consideration component wear over time and other similar issues. In addition, the processing system can take an action based on its determination so as to avoid or prevent overload conditions.

With reference to <FIG>, <FIG>, <FIG>, a predictive system <NUM> (see <FIG>) is provided for use with a torque-limiter, such as a ball-ramp mechanism or another similar mechanism of an aircraft <NUM>, for example.

In the exemplary cases of <FIG> and <FIG>, the aircraft <NUM> includes a fuselage <NUM> and a wing <NUM> extending outwardly from the fuselage <NUM>. The wing <NUM> includes one or more flight control surfaces <NUM>, such as slats or flaps, that are arranged along a trailing edge of the wing <NUM> and which are pivotable relative to a major plane of the wing <NUM> for executing various flight maneuvers. The pivoting of the flight control surfaces <NUM> is driven by a control unit <NUM> which is coupled to the flight control surfaces <NUM> by way of a drivetrain <NUM> and a series of linear or rotary actuators <NUM>. Torque for powering the pivoting is generated in the control unit <NUM> and transmitted along the drivetrain <NUM> through one or more torque-limiters <NUM> that may be separate from (see <FIG>) or integrated within (see <FIG>) the actuators <NUM>.

Each of the torque-limiters <NUM> operate by preventing application of excessive load to aircraft structures in the case of an external issue. Often, the actuators <NUM> fail as a result of internal tare losses that exceed design parameters due to water ingress or faulty maintenance leading to corrosion or gear wear. The failure in turn leads to high input torque being required to make the actuator <NUM> move or respond. Eventually, the problem decays until the required torque exceeds a threshold of the torque-limiters <NUM>.

Conventional torque-limiter systems include tripped spring indicators that provide a visual indication of a trip incident. This trip indication needs to be observed, however, and such observation is typically preceded by removal of one or more aircraft panels. As will be described herein, a sensor is provided to sense conditions of the torque-limiters <NUM> which do not necessarily rise to the level of a full tripping incident. Such conditions, once sensed or detected, may be compared against prior flight data and other information to aid in a determination that maintenance is or is not required.

As shown in <FIG>, a torque-limiter <NUM> is provided as a ball-ramp mechanism <NUM>. The ball-ramp mechanism <NUM> includes an input shaft <NUM> and an output shaft <NUM> which may be components of the drivetrain <NUM> of <FIG> and <FIG>. The ball-ramp mechanism <NUM> further includes a first plate <NUM> to which the input shaft <NUM> is coupled, a second plate <NUM> to which the output shaft <NUM> is coupled, a ball element <NUM> which is disposable within complementary recesses <NUM> and <NUM> in the first and second plates <NUM> and <NUM>, respectively, and a spring-loading assembly <NUM> that biases the first plate <NUM> toward the second plate <NUM> on either side of the ball element <NUM>.

During normal operations, the ball element <NUM> is secured within the complementary recesses <NUM> and <NUM> so that torque can be transmitted from the input shaft <NUM>, to the first plate <NUM>, to the ball element <NUM>, to the second plate <NUM> and finally to the output shaft <NUM>. However, in a case in which elevated torque is applied to the ball-ramp mechanism <NUM> as a result of, for example, the corresponding actuator <NUM> being corroded but not excessively corroded, the ball element <NUM> may translate slightly outwardly from the recesses <NUM> and <NUM> without actually leaving the recesses <NUM> and <NUM>. This will have the effect of pushing the first and second plates <NUM> and <NUM> slightly apart but will still permit torque transmission from the input shaft <NUM> to the output shaft <NUM>. In a case in which excessive torque is applied to the ball-ramp mechanism <NUM> as a result of, for example, the corresponding actuator <NUM> being excessively corroded, exhibiting degraded lubrication, exhibiting excessive gear or bearing wear or experiencing an introduction of foreign material (e.g., sand, dust, etc.) or in the case of degradation of another related or unrelated component, the ball element <NUM> may translate completely out from the recesses <NUM> and <NUM>. This will have the effect of pushing the first and second plates <NUM> and <NUM> apart and will prevent torque transmission from the input shaft <NUM> to the output shaft <NUM>.

The predictive system <NUM> includes at least one or more sensors (hereinafter referred to as "a sensor") <NUM>, a processing system <NUM> and a housing <NUM> in which the torque-limiter <NUM>/ball-ramp mechanism <NUM> and the sensor <NUM> are mounted so as to be normally fixed relative to one another. The sensor <NUM> may be provided as at least one or more of an optical sensor, an electromagnetic sensor, a Hall Effect sensor, a linear variable differential transformer (LVDT) sensor and a capacitive sensor. In any case, the sensor <NUM> is disposed to sense a condition of the torque-limiter <NUM> or, more particularly, the ball-ramp mechanism <NUM>. In accordance with embodiments, sensor <NUM> may sense a first distance D1 (see <FIG>) between the first plate <NUM> and the sensor <NUM> such that the sensor <NUM> effectively senses a second distance D2 (see <FIG>) between the first and second plates <NUM> and <NUM>. Here, the first and second distances D1 and D2 may but are not required to extend along a dimension that is defined along a longitudinal axis of the input and output shafts <NUM> and <NUM>.

With continued reference to <FIG> and with additional reference to <FIG>, the processing system <NUM> is coupled to the sensor <NUM> and, in some cases, to at least one or more of the control unit <NUM> and a flight control computer (FCC) <NUM> of the aircraft <NUM>. The processing system is configured to process readings of the sensor <NUM>, to calculate whether the second distance D2 between the first and second plates <NUM> and <NUM> is indicative of degradation or failure incidents in at least any one or more of the drivetrain <NUM> (see <FIG> and <FIG>), the actuators <NUM> (see <FIG> and <FIG>) and the ball-ramp mechanism <NUM> based on the readings being processed and to determine whether an action should be taken based on a calculation result. To this end, the processing system <NUM> may include or be provided as at least one or more of a controller <NUM> and a prognostic maintenance computer <NUM>. In any case, the processing system <NUM> may include a processor <NUM>, such as a central processing unit (CPU), a memory unit <NUM> and a networking unit <NUM> by which the processor <NUM> is communicative with the sensor <NUM> and, where applicable, the control unit <NUM> and the FCC <NUM>. The memory unit <NUM> has data stored thereon which is reflective of at least historical sensor readings <NUM> from the ball-ramp mechanism <NUM> or from other ball-ramp mechanisms and executable instructions. When executed by the processor <NUM>, the executable instructions cause the processor <NUM> and the processing system <NUM> as a whole to operate as described herein.

Exemplary operations of the processing system <NUM> will now be described with reference to <FIG>.

As shown in <FIG>, the ball-ramp mechanism <NUM> is operating normally with the ball element <NUM> secured in the recesses <NUM> and <NUM>. As such, the sensor <NUM> senses that the first distance D1 between the sensor <NUM> and the first plate <NUM> is large enough to infer that the second distance D2 is short due to the ball element <NUM> being secured in the recesses <NUM> and <NUM>.

As shown in <FIG>, the ball-ramp mechanism <NUM> is able to transmit torque but is not operating normally due to the ball element <NUM> translating slightly outwardly from the recesses <NUM> and <NUM>. As such, the sensor <NUM> senses that the first distance D <NUM> between the sensor <NUM> and the first plate <NUM> is reduced as compared to the first distance D1 of <FIG> and thus it can be inferred that the second distance D2 is correspondingly elevated due to the ball element <NUM> being unsecured in but not completely removed from the recesses <NUM> and <NUM>.

As shown in <FIG>, the ball-ramp mechanism <NUM> is incapable of transmitting torque due to the ball element <NUM> being completely removed from the recesses <NUM> and <NUM>. As such, the sensor <NUM> senses that the first distance D1 between the sensor <NUM> and the first plate <NUM> is reduced as compared to the first distance D1 of <FIG> and thus it can be inferred that the second distance D2 is correspondingly elevated as compared to the second distance D2 in <FIG> due to the ball element <NUM> being completely removed from the recesses <NUM> and <NUM>.

For the case illustrated in <FIG>, the condition of the torque-limiter <NUM> is indicative of an increased torque but not necessarily a torque overload due to the second distance D2 between the first and second plates <NUM> and <NUM> of the ball-ramp mechanism <NUM> exceeding a first threshold but not reaching a second threshold. In this case, the processing system <NUM> may predefine the first threshold in accordance with at least the structural features of the ball-ramp mechanism <NUM> and the historical data of the memory unit <NUM> and take an action which is consistent with a conclusion that the condition is indicative of some degradative incident in the drivetrain <NUM>, the actuator <NUM> or the torque-limiter <NUM>/ball-ramp mechanism <NUM>. Such action may include identifying a location of the torque-limiter <NUM> in question so that remote panel removal and inspection is not needed and at least one of instructing the control unit <NUM> to reduce applied torque by way of the controller <NUM> and arranging for maintenance by way of the prognostic maintenance computer <NUM> (e.g., scheduling an inspection or repair, ordering parts, etc.).

For the case illustrated in <FIG>, the condition of the torque-limiter <NUM> is indicative of a torque overload due to the second distance D2 between the first and second plates <NUM> and <NUM> of the ball-ramp mechanism <NUM> reaching or substantially reaching the second threshold (the second threshold may not be able to be exceeded). In this case, the processing system <NUM> may take an action which is consistent with a conclusion that the condition is indicative of some failure incident in the drivetrain <NUM>, the actuator <NUM>, the torque-limiter <NUM> or the ball-ramp mechanism <NUM>. Such action may include identifying a location of the torque-limiter <NUM> in question so that remote panel removal and inspection is not needed, instructing the control unit <NUM> to reduce or cease applied torque by way of the controller <NUM> and arranging for maintenance by way of the prognostic maintenance computer <NUM> (e.g., scheduling an inspection or repair, ordering parts, etc.).

With reference to <FIG>, a method of operating a predictive system for a torque-limiter as described above is provided. As shown in <FIG>, the method includes sensing a condition of the torque-limiter, such as a distance between plates of a ball-ramp mechanism (block <NUM>), calculating whether the condition of the torque-limiter is indicative of a degradation or failure incident (block <NUM>), determining whether an action should be taken based on a calculation result (block <NUM>) and taking the action based on a result of the determining of block <NUM> (block <NUM>).

In accordance with embodiments, the calculating of block <NUM> may include calculating that the distance exceeds a first threshold without reaching a second threshold (block <NUM>), determining that the condition is indicative of the degradation incident based on the distance exceeding the first threshold without reaching the second threshold (block <NUM>), calculating that the distance reaches the second threshold (block <NUM>) and determining that the condition is indicative of the failure incident based on the distance reaching the second threshold (block <NUM>).

Claim 1:
A predictive system (<NUM>), comprising:
a torque-limiter (<NUM>) comprising a ball-ramp mechanism (<NUM>);
a sensor (<NUM>) disposed to sense a condition of the torque-limiter , the condition comprising a distance between plates of the ball-ramp mechanism; and characterized by:
a processing system (<NUM>) coupled to the sensor and configured to process readings of the sensor, to calculate whether the condition of the torque-limiter is indicative of degradation or failure incidents based on the readings being processed and to determine whether an action should be taken based on a calculation result;
wherein the processing system (<NUM>) is configured to calculate that the condition of the torque-limiter is indicative of the degradation or failure incidents based on the condition exceeding a first threshold or reaching a second threshold, respectively.