Material wear indication system

A material wear indication system is provided that includes a friction plate capable of engaging a moving surface and a wear indicator. The friction plate includes a wearable portion and a non-wearable portion. In one embodiment the wear indicator is embedded in the non-wearable portion and is prevented from contacting the moving surface until the wearable surface has been sufficiently eroded. When the wear indicator contacts the moving surface it emits a particulate matter that can be detected by a sensor. The sensor is operable to generate an electrical signal that is transmitted to a control unit when the wearable surface has eroded thereby exposing the wear indicator to the moving surface.

FIELD OF THE INVENTION

The present invention generally relates to friction plates, and more particularly, but not exclusively, to a method and system of detecting wear in friction plates.

BACKGROUND

Detecting when friction plates, such as brake pads and clutches, have become sufficiently worn remains an area of interest. Unfortunately, some existing systems have various shortcomings relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology.

SUMMARY

One embodiment of the present invention is a unique friction plate and system. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for detecting wear in friction plates. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

One aspect of the present application includes a friction plate, such as a clutch, operable to engage a moving surface and having a wearable portion and a non-wearable portion. A wear indicator is embedded in the non-wearable portion and is protected from the moving surface by the wearable portion of the friction plate. When, however, the wearable portion has sufficiently eroded, the wear indicator becomes exposed and releases a particulate matter. The particulate matter is detected by a sensor to indicate when the friction plate may be replaced or other maintenance is otherwise needed.

Referring toFIGS. 1 and 2, a material wear indication system10is disclosed that is operable to notify maintenance personnel when maintenance may be required on a multiple plate clutch assembly12. The material wear indication system10includes at least one sensor14that is coupled with the multiple plate clutch assembly12and a vehicle control unit16. The multiple plate clutch assembly12includes an input plate30and an output plate32.

While the illustrative embodiment has been disclosed as a multiple plate clutch assembly12, those skilled in the art should recognize that the present invention may be utilized in single clutch plate systems as well. Further, the present invention may be utilized in brake systems and any other type of system that utilizes friction plates or discs. In addition, while the preferred discs or plates are disclosed as two-sided friction plates, one-sided friction plates utilizing the present invention are also envisioned and incorporated herein.

Each of the input plates30and output plates32have a wearable surface33and may include at least one wear indicator40. In some embodiments, however, less than all of the input plates30and/or output plates32may have a wear indicator40. To set forth just one nonlimiting example, in some embodiments only the output plates32may include wear indicators40, or perhaps every other output plate32. Each of the input plates30and output plates32may have wearable surfaces33that are made of different substances or materials such that the amount of wear caused by relative movement may vary between the input plates30and output plates32. In some embodiments it is also possible that a wearable surface33on one side of an input plate30may be made of a different material or substance than a wearable surface33disposed on the other side of the input plate30. The same is true of different wearable surfaces of the output plates32.

In one embodiment, the wear indicators40are shown disposed within the input plates30and output plates32and are configured to wear and/or erode when there is relative movement between mating surfaces of input plates30and output plates32. The wear indicators40are exposed to a neighboring plate or to the ambient environment surrounding the plates when a sufficient amount of wearable surface33has been removed by relative movement between the plates. The wear indicators are configured to emit a particulate matter when exposed, either instantaneously or upon further relative movement of the input plates30and output plates32. The particulate matter is different than any particulate matter emitted by the wearable surface33.

The wear indicators40disposed within each of the plates30,32may be configured to release particulate matter at varying levels of wear or erosion of the wearable surfaces33. For example, a greater amount of wear and/or erosion of the input plates may be required, relative to the output plates32, before the particulate matter is released from the wear indicators40. In this way it may be possible to detect when the input plates have reached a particular erosion level. Likewise, some input plates30may require greater wear and/or erosion, relative to other input plates30, before particulate matter is released from the wear indicators40. In this way it may be possible to detect when a particular input plate has reached a particular erosion level.

Some wear indicators may be disposed in varying locations or numbers. Though the wear indicators40are shown disposed generally along a common line, some embodiments may have the wear indicators40distributed along another arrangement, or may be random. In some embodiments, the wear indicators40may be disposed at a periphery of the plates30,32. In addition, though each of plates30,32are shown having a single wear indicator40, some plates may have more than one wear indicator40.

The multiple plate clutch assembly12includes a cover or housing70that encompasses or houses the components of the multiple plate clutch assembly12. In this embodiment, the housing70defines a cavity72in which the components of the multiple plate clutch assembly12may be housed. A clutch exhaust aperture74is included in the housing70that allows the multiple plate clutch assembly12to vent particulates that are shed by the wear indicators40. In some embodiments, however, the housing70may not include an exhaust aperture74such that any particulate matter released by the wear indicators40is contained within the housing70. The speeds at which the plates30,32rotate creates an airflow in the cavity72that directs the particulates that come off of the wearable surfaces54,56and exit the cavity72.

Sensors14are provided internal to the housing70and within the aperture74and are used to detect the particulate material released by the wear indicator40. In some embodiments, the sensors14may be used to detect particulate matter emitted from the wearable surface33. The sensors may reside solely within housing70, solely in the aperture74, or solely downstream of aperture74in other embodiments, depending upon the needs of any given application. Though the illustrated embodiment discloses multiple sensors, in some embodiments a single sensor may be appropriate.

The sensors14generate a signal upon detection of particulate matter, which signal is then transmitted to the vehicle control unit16discussed further hereinbelow. In some embodiments the sensors only transmit a signal upon request, either from a vehicle control unit16or other device. In other embodiments a light, alarm, or other type of device may be activated directly by the sensor as opposed to being routed through a vehicle control unit16.

The sensors14may generate a signal upon detecting a sole particle of the particulate matter, or may generate a signal upon detecting a threshold number of particles. In some embodiments the strength, magnitude, frequency, or other characteristic of the signal may vary depending upon the number of particles, rate of detected particles, or concentration of particles. In other embodiments the sensor signal may merely be binary as a function of a single particle or multiple particles.

Different types of sensors14may be used depending on the application. The sensors14may be selected from a group of sensors consisting of a magnetic plug, a sensor operable to detect electromagnetic radiation, and/or a gas sensor, among others. In some embodiments, all sensors14may be of the same type. In other embodiments, however, different types of sensors may be simultaneously used in the material wear indication system10. For example, in some embodiments, a gas sensor may be used in conjunction with a magnetic plug, or any other type of sensor.

In one embodiment, the wear indicators40may comprise a ferrous material/magnetically attractable material and the sensors14may comprise a magnetic plug. As the ferrous particulates are shed, they are picked up by the air flow and pass by the magnetic plugs, which capture the particulates due to the magnetic characteristics of the particulates. Once the sensor14senses that ferrous particulates have been captured, a signal is generated that is sent to the control unit16indicating that a respective plate30,32has reached an erosion level that requires maintenance.

In another embodiment, the wear indicators40may comprise a colored material and the sensors14may comprise an optical sensor. As colored particulates are shed, they are detected by the optical sensor and, as previously set forth, the sensor14generates a signal that is sent to the control unit14. The plates30,32of the multiple plate clutch assembly12may have different colored materials embedded in the apertures60such that different colored particulates are shed to indicate a specific plate30,32that requires maintenance.

In yet another embodiment, the wear indicator40may comprise a gaseous material and the sensors14may comprise a gas sensor. As gas particulates are released, they are detected by the gas sensor as they exit the clutch exhaust aperture74. Different types of gas material may be used in each respective plate30,32to indicate a specific plate30,32that requires maintenance. As in the previous embodiments, detection of gas particulates causes the sensors14to generate a predetermined electric signal that is sent to the control unit16.

The vehicle control unit16includes a communication port18that is operable to allow the vehicle control unit16to report the existence of a maintenance issue related to friction disc wear in the multiple plate clutch assembly12. The communication port18may comprise a wireless communication port or a traditional connector-type communication port. The vehicle control unit16is connected with a maintenance control unit20via the communication port18. This allows the vehicle control unit16to communicate the existence of maintenance issues to the maintenance control unit20, which may reside on a vehicle or external to the vehicle. The vehicle control unit16is connected with a display device22that is operable to display a maintenance warning or message.

If the multiple plate clutch assembly12was installed in an aircraft, for example, a wear indication signal may be generated and sent to the vehicle control unit16when the sensor14detects particulate matter from one or more wear indicators40. Once the vehicle control unit16is in communication range of the maintenance control unit20, a plate maintenance indication may be transmitted to the maintenance control unit20to alert ground maintenance personnel of the issue. This may occur, for illustrative purposes only, when an aircraft that includes the multiple plate clutch assembly12lands and is checked by ground maintenance personnel or when the aircraft comes within range of the wireless communication port.

Various embodiments of the material wear indication system10disclosed herein are capable of notifying maintenance crews when one of the respective plates30,32wears out or is worn out to a predefined level, without the need to periodically disassemble and visually inspect the system. It will be understood that the maintenance crews, or other personnel, can be notified whether or not a vehicle control unit16is provided. For example, a handheld device may be used to interface directly with sensor14to query whether one or more of plates30,32have worn out. In this way sensor14may be configured to delay sending a signal representative of the particulate matter until requested.

As used herein, the term aircraft includes, but is not limited to, helicopters, airplanes, unmanned space vehicles, fixed wing vehicles, variable wing vehicles, rotary wing vehicles, hover crafts, vehicles, and others. Further, the present inventions are contemplated for utilization in other applications that may not be coupled with an aircraft such as, for example, industrial applications, power generation, pumping sets, naval propulsion and other applications known to one of ordinary skill in the art.

Referring more closely toFIG. 2, a partial cross-section of the multiple plate clutch assembly12is illustrated. The input plates30and output plates32are annular in shape and are mounted for rotation about a horizontal axis (H). The input plates30are connected with a clutch power transmission input shaft38, and the output plates32are connected with a clutch power transmission output shaft36. A clutch plate clamp shaft34is used to engage the input plates30to the output plates32.

During one phase of operation of the multiple plate clutch assembly12, the output plates32are relatively motionless while the input plates30are rotated about horizontal axis (H) through rotation of the clutch power transmission input shaft38. As the clutch plate clamp shaft34is operated to bring the rotating input plates30into contact with the relatively motionless output plates34, the wearable surfaces33of the plates wear and/or erode some amount while the output plates32respond to and are brought up to the same rotational speed as the input plates30, thus causing identical rotational motion in the clutch power transmission output shaft36. During this operation the load on the clutch power transmission input shaft38may increase thus causing a slowdown, which may be offset by the addition of power to the shaft.

Referring toFIG. 3, one embodiment of the wear indicator40is shown having a cylindrical shape; however, other shapes and various sizes are contemplated. The wear indicator40may comprise any device or substance capable of emitting particulate matter, such as a ferrous material, a colored material, or a gas emitting material. As used herein the term colored denotes a wavelength in the electromagnetic spectrum, whether in the visible band or another, such as the infrared. For example, the wear indicator40may include a variety of materials that provide different heat signatures when released as particulates that can be detected by infrared sensors. In other embodiments, the wear indicator may include a liquid substance covered by a membrane such that when the membrane is breached the liquid is released. The liquid may be evaporated to create a gaseous particulate matter such as a gas molecule.

The various input plates30and output plates32may utilize different wear indicators40. For example, in some embodiments the input plates30may collectively utilize one type of wear indicator40while the output plates32utilize another. In other embodiments, some input plates30may utilize different wear indicators40than other input plates30. Varying the types of wear indicators40used in the multiple plate clutch assembly12may allow for precise detection of the wear of a particular plate. For example, if a first input plate30used a colored material and a second input plate used a gas emitting material, then it may be determined that the first input plate30needs to be replaced when colored material is detected by a sensor.

Referring toFIG. 4, an end view of one embodiment of a friction plate assembly94is depicted. The friction plate assembly94is shown having a generally circular shape and includes a plurality of outside diameter lugs42aand a plurality of inside diameter lugs42b. The assembly94includes plates30,32and may be manufactured in varying sizes to suit a particular application. The outside diameter lugs42aare used to engage, in a male/female arrangement or fashion, similar lugs on the clutch power transmission output shaft36. Similarly, the inside diameter lugs42bare used to engage the clutch power transmission input shaft38. The clutch power transmission input shaft38resides in interior90of the friction plate assembly94, and the power transmission output shaft36resides in the exterior92.

Referring toFIG. 5, a partial cross sectional view of a respective friction plate assembly94is illustrated along line A-A inFIG. 4. Shown inFIG. 5is one embodiment of the single output plate32discussed above. The output plate32includes a first non-wearable surface50, a second non-wearable surface52, a first wearable surface54, and a second wearable surface56. The various surfaces50,52,54, and56are connected together using a plurality of rivets58, but various other types of connection mechanisms or devices may also be utilized in the present invention (e.g.—bolts, screws, and so forth). Additionally and/or alternatively, the various surfaces50,52,54, and56may be bonded together.

The non-wearable surfaces50,52may be manufactured from a metal alloy, steel, or any other material commonly known and used in the industry. The wearable surfaces54,56may be manufactured from a carbon/carbon composite material or any other material commonly utilized in friction plate or brake technology. The wearable surfaces54,56wear out after some amount of repeated frictional engagements with a surface that moves relative to the wearable surfaces, such as an input plate30. As the input and output plates30,32are repeatedly engaged, the wearable surfaces54,56begin to erode or wear out, as commonly known in the art and as described hereinabove.

The non-wearable surfaces50,52include a plurality of apertures60that may be spaced evenly, or randomly, around the non-wearable surfaces50,52. The apertures60may extend through the width of the non-wearable surfaces50,52. The wear indicators40are embedded in the apertures60of the non-wearable surfaces50,52by way of a friction fit, gluing, epoxy, or any other similar manner of embedding objects in place. In some embodiments, however, the wear indicators40may be interwoven or otherwise integrally formed with the non-wearable surfaces50,52.

In one embodiment, the wear indicators40may be embedded in the wearable surfaces54,56such that a portion of the wear indicators40protrude into the wearable surfaces54,56a predetermined distance as illustrated inFIG. 5. In addition, similar to the non-wearable surfaces50,52, the wear indicator40may be interwoven or otherwise integrally formed with the wearable surfaces54,56. In one embodiment, the wear indicators46may lie adjacent to an outward edge62of the wearable surfaces54,56. In either embodiment, the wear indicators40are positioned such that they designate or indicate a particular erosion level, which is indicated by the dashed line64inFIG. 5. The particular erosion level64may be set based on a number of considerations. For example, the erosion level64may be set to provide sufficient margin in the remaining useful life of the input and output plates, to set forth just one nonlimiting example.