Work machine with a differential protection system and method

A work machine with a differential protection system includes an electronic differential lock, a controller, and a knock sensor to convert sensed vibrations into electric signals. The controller is programmed to receive and process the electrical signals generated by the knock sensor, determine a risk of differential lock wear based on the processed signals. The program instructions include responding to the processed signals indicative of a risk of differential lock wear by inhibiting locking of the differential lock for a defined time period, and command locking the differential lock as a response to expiration of the defined period. The controller may further be programmed to command locking the differential lock as a response to a request to lock the differential lock and engagement conditions being met. The presence of a risk of differential wear is derived from a frequency and an amplitude of the processed signals.

TECHNICAL FIELD

The present disclosure relates generally to a work machine with a differential protection system for controlling the locking and unlocking of the differential depending on a risk to the health of the differential to prevent hardware damage to the differential.

BACKGROUND

The health of differentials can significantly impact the performance of a work machine. For example, an articulating dump truck relies on its differential locks to distribute power evenly between the wheels and maintain traction in various terrains and under varying payloads. Worn differentials can impact the degree of engagement and can thereby result in a power imbalance and reduced traction if the locking mechanism is improperly engaged. This can be especially challenging in navigating uneven and slippery surfaces, especially during uphill or downhill operations. Differential wear can also affect the stability and maneuverability of the work machine, especially with large payloads. This engagement of automatic differential locks is typically based on pre-defined conditions, including slip detection. However, disengagement of the differential lock(s) post engagement can be sub-optimal because once the differential is mechanically locked, slip is no longer detectable and therefore can no longer be reliably disengaged consistently to avoid premature wear. The industry standard is to include a preset timer to automatically disengage the differential locks.

However, the variability of ground conditions, surface materials and route paths can cause scenarios where the differentials can be damaged or prematurely worn by turning (even slightly) with the differentials locked. Turning the vehicle in non-slippery ground conditions with the differentials locked can cause damage even if the system functions as designed. That is, a preset timer may result in periods when the differential is locked during no slip conditions resulting in both wheels rotating at the same speed, regardless of the traction or resistance encountered, or the turning angle. Therein lies an opportunity to improve how and when the differential locks engage and disengage.

SUMMARY

According to an aspect of the present disclosure, a work machine with a differential protection system and method is disclosed. The work machine includes a knock sensor, an electronic locking differential, and a controller. The knock sensor is configured to convert sensed vibrations into electric signals. The controller is programmed to receive and process the electrical signals generated by the knock sensor, determine a presence or a severity of a risk of differential wear based on the processed signals indicative of a risk of differential wear. The program instructions also include responding to the processed signals indicative of a risk of differential wear by inhibiting locking of the differential for a defined period. The controller may further be programmed to command locking of the differential as a response to expiration of the defined period. The controller may further be programmed to command locking the differential as a response to a request to lock the differential and engagement conditions being met. The controller may further be programmed to command locking of the differential responsive to a request to lock the differential, engagement conditions being met, and expiration of the defined period. Engagement conditions can include the steering angle and the speed of the work machine being less than a steering angle threshold and a speed threshold. The risk of differential wear is derived from a frequency and an amplitude of the processed signals. The controller may further be programmed to store information of the processed signals indicating detected vibration abnormalities and provide an alert when the processed signals indicating detected abnormalities exceed a threshold. The risk of differential wear is derived from a frequency and an amplitude of the processed signals. The controller may further store information of the processed signals indicating detected vibration abnormalities and provide an alert when the processed signals indicate detected abnormalities exceed a threshold.

In another embodiment, an articulating work machine comprises a front chassis, a front knock sensor coupled to the front chassis wherein the front knock sensor is configured to convert a sensed vibration into electrical signals, and a front electronic differential lock. The articulating work machine also includes a rear chassis, a rear knock sensor coupled to the rear chassis wherein the rear knock sensor is configured to convert a sensed vibration into electrical signals, and a rear electronic differential lock(s). An articulation joint is disposed between the front chassis and the rear chassis wherein the articulation joint enables relative pivotal movement between the front chassis and the rear chassis along a vertical axis wherein the articulation joint facilitates the steering of the work machine. The controller is programmed to energize a locker to lock one of the front electronic differential lock and the rear electronic differential lock in response to a work machine speed and a steering angle being less than a threshold. The controller then receives and processes the electrical signals generated by the front knock sensor and the rear knock sensor. The controller is then programmed to determine a risk of differential wear based on the processed signals, deenergize the locker to unlock one of the front differential and the rear differential in response to signals indicative of worn differential locks. In response to the processed signals indicative of a risk of differential wear, the controller is programmed to inhibit locking of the differential for a defined period.

The controller may further be programmed to command locking of the differential in response to expiration of the defined period.

The controller may further be programmed to, in response to a request to lock the differential and engagement conditions being met, command locking the differential.

The controller may further be programmed to command the differential as a response to a request to lock the differential, engagement conditions being met, and an expiration of the defined period. The engagement condition includes one of a work machine speed and a steering angle being less than a threshold.

A method for performing predictive differential control on a work machine comprises, in a first step, receiving and processing a historical electrical signal data generated by a knock sensor associated with the presence or a severity of a sensed vibration of a differential lock. Then the method includes extracting one or more features from the processed historical electrical signal data wherein the one or more features associated with the wear of the differential track. In a next step, the method includes training a predictive model using the one or more features and a labeled dataset regarding a health information of the differential lock. Next the method includes applying the predictive model to the one or more features to generate a prediction of the health information of the differential lock. In a next step, the method includes unlocking the differential in response to a processed electrical signal indicative of a risk of differential wear, and inhibiting locking of the differential for a defined period that starts in response to the unlocking of the differential. The defined period is based on the health information of the differential lock. A feature from the historical electrical signal data comprises one or more of a steering angle, and a speed of the work machine. The method further includes storing information of the processed signals indicating detected vibration abnormalities and providing an alert when the processed signals indicating detected abnormalities exceed a threshold. The method further comprises commanding locking the differential in response to expiration of the defined period. The method applies to one or more of a front electronic differential coupled to a front chassis and a rear electronic differential coupled to a rear chassis. The feature from the historpical electrical signal data comprises one or more of a frequency of the processed signals, and an amplitude of the processed signals.

Other features and aspects will become apparent by consideration of the detailed description, claims, and accompanying drawings.

Like reference numerals are used to indicate like elements throughout the several figures.

DETAILED DESCRIPTION

FIG.1illustrates an exemplary embodiment of an articulating work machine100shown as an articulating dump truck, that includes a cab portion106and a trailer portion104. Cab portion106includes a first frame107, and trailer portion104includes a second frame105. First frame107is connected to second frame105through a coupling assembly110. In the illustrated embodiment, coupling assembly110includes a pivot frame coupling112and a rotational frame coupling114. Pivot frame coupling112provides for articulating movement or pivoting, of second frame105relative to first frame107about a vertical axis116. Rotational frame114coupling provides for rotation movement of second frame105relative to first frame107about a longitudinal axis118. In one embodiment, work machine100may include one or more hydraulic actuators to control the angle between the first frame107and second 105 frames for steering the work machine100.

First frame107illustratively supports a cab portion106and an engine or battery power source for propelling the work machine100. A first or front wheel assembly122includes a pair of wheels for providing rolling support to cab portion106. A dump body or bin126for containing a load is supported by second frame105. An actuator, such as a hydraulic cylinder, may be coupled to bin for angularly elevating bin relative to the second frame105.

A second or rear wheel assembly128is operably coupled to second frame105for supporting the trailer portion104. Referring toFIG.2with continued reference toFIG.1, the rear wheel assembly128illustratively includes a first rear wheel assembly124and a second rear wheel assembly130. First and second rear wheel assemblies each illustratively include a left wheel and a right wheel. In the illustrated embodiment, each of first rear wheel assemblies124, and the second rear wheel assemblies are rotatably coupled to a tandem or walking beam. Work machine100may include alternative wheel assembly configurations. For example, fewer or more wheels and/or axles may support trailer portion104, and/or cab portion106.

Now turning toFIG.2with continued reference toFIG.1, the front wheel assembly122includes a front axle132coupled between wheels, and a differential134coupled to the front axle132. Alternatively, the first rear wheel assembly124and the second rear wheel assembly may function like a bogie axle wherein the first rear axle138includes a first differential142, and the second rear axle140includes a second differential144.

The differential locks (146a,146b,146c, collectively referred to as146) selectively disengage or lock the differential (134,142,144). When engaged, a differential lock146essentially turns the differential into a solid shaft, forcing both wheels on an axle to rotate at the same speed. In one exemplary embodiment, the differential locks (146a,146b,146c) may include a clutch assembly. In particular, when the lock146is engaged or closed, the differential (134,142,144) is in a locked state, and a first portion (not shown) of the drive shaft is locked to a second portion (not shown) to rotate therewith. One or more than each of the differentials (134,142,144) may be locked. When the lock146is disengaged or opened, the differential is in an unlocked and operational state, thereby allowing the first portion (not shown) and second portion (not shown) to rotate at different speeds. The differential lock146may be configured to completely lock the differential or to partially lock the differential. For example, lock146may limit rotation of front portion or drive shaft relative to second portion of drive shaft without completely locking front portion to second portion. Furthermore, not every differential lock (146a,146b, and146c) needs to be engaged simultaneously because the lock disposition will rely on the individual state of each respective differential (132,142,144) and slip conditions.

In one embodiment, the differential lock (146a,146b, and146c) includes an electronic differential lock150that is in communication with the controller148. The differential lock (146a,146b, and146c) includes an electronically actuated locker configured to lock the left and right half shafts relative to each other when engaged and permit relative rotation between the half shafts when disengaged. The differential locks146are in communication with the controller148and locks the differential150in response to a command from their respective controller (148a,148b) through an electronically actuated mechanism such as a differential lock solenoid.

The electronic differential lock150has an unlocked state (disengaged) in which the half shafts are permitted to rotate independent of each other, and a locked state (engaged) in which the half shafts are rotationally fixed to each other. The differential150may be placed in the locked state by coupling the half shafts via an electronically actuated mechanism such as a differential lock solenoid.

Work machines equipped with electronic differential locks150may include controls for monitoring the work machine speed178and steering angle176so that the lock150of the differential is not commanded when the work machine speed178or the torque of the powertrain exceeds a threshold. That is, a differential lock (146a,146b, and146c) should generally not engage at high speeds and sharp turns. However, the monitoring of work machine speed178, and steering angle176alone may be insufficient to prevent ratcheting and thereby creates a risk of differential wear in all operating conditions with no slip by the work machine100.

In the present embodiment, the work machine100includes a differential protection system500and a knock sensor160adapted to convert sensed vibrations167into electrical signals169. The knock sensor can advantageously anticipate an unwanted and potentially damaging phenomenon caused by worn differential locks146by detecting ratcheting type sounds. Each respective knock sensor (146a,146b,146c) is typically mounted in proximity to its respective differential lock (134,142,144) and is designed to detect the vibrations and noise associated with sudden changes caused by a worn differential lock.

The threshold at which a knock sensor senses engine knock can vary depending on the specific design and calibration of the sensor. Generally, knock sensors are sensitive to small vibrations and noise levels that are characteristic of engine knock. They are designed to detect these abnormal combustion events and send a signal to the engine control unit (ECU) to adjust the ignition timing or fuel mixture to prevent further knock and protect the engine from damage.

The differential protection system500controls the locking and unlocking of the differential lock (146a,146b, and146c) depending on the health of components (i.e. wear) to prevent hardware damage to the differential134.

As seen in the differential protection system flow diagram ofFIG.3, in a first step310a detected slip event will automatically initiate an application of a differential lock (146a,146b, and146c) provided certain engagement conditions174are met. This initiation results in step320when the automatic differential lock146is applied. Once this occurs, three features (steps332,334, and330) are simultaneously monitored wherein in one or more of these features (332,334,330) may result in disengagement of the automatic differential lock (146a,146b, and146c) (i.e. unlocking of the electronic differential lock150) at step350in response to the electrical signals169received and processed from the knock sensor160indicating a risk of differential wear. In step355, the controller148further has instructions to continue inhibiting locking of the electronic differential lock150for a defined period in response to the risk of differential wear. For example, the differential lock150remains locked so long as ratcheting is not sensed. Now returning to step330, the controller148is programmed to receive the electrical signals169generated by the knock sensor160that are derived from sensed vibrations167and determine a risk of differential wear based on these processed signals170. A processor87in the controller148may use a filtering mechanism adapted to filter out noise and irrelevant vibrations to further process the electrical signals169generated by the knock sensor160. The signal processor87may further determine the frequency and amplitude of knocking vibrations, allowing the controller148to respond to indications of the risk of differential wear based on the severity and characteristics of the detected knocking events as derived from the processed signals170.

The controller148is further programmed to include unlocking the differential134in step350in response to detected processed signals170indicative of worn differential locks from step340. Differential wear may exhibit a grinding, clanking, or whining type sound. These sounds can be caused by a lack of lubrication, worn differentials, or simply locking the differential in conditions with slip. The identification of processed signals170indicative of a risk of differential wear may include electrical signals169from a range either a machine-learned data with use and analyzation of historical data, or simply a predetermined threshold. This diagnostic mechanism integrated into the controller148is adapted to store information about the detected knocking events, and to provide alerts or notifications to the work machine operator or maintenance personnel for further investigation when knocking events exceed a determined threshold and/or disengage the differential lock (146a,146b, and146c). Another means of determining when to disengage a differential lock (146a,146b, and146c) include monitoring of engagement conditions174as in step334wherein the disengagement condition174may include steering angle176or a work machine speed178. Current industry standards typically include usage of a timer as seen in step332, wherein the respective differential lock146disengages after a timed period as seen in step342. For automatic differential lock146engagement and disengagement, each axle (122,124,128) may act independently of one another. In the present embodiment of the articulating dump truck, the front differential lock146acoupled to the front axle132may respond to a front frame controller148aand a front knock sensor160a. The mid differential lock146bcouple to a first rear axle138and the rear differential lock146ccoupled to a second rear axle140may respond to a rear frame controller148b.

Finally, the program instructions responsive to the processed signals170indicative of worn differential locks, disengage the differential134for a defined period or until the processed signals170indicative of a risk of differential wear ends (i.e. returns to normal operating conditions). The disengagement of the automatic differential locks (146a,146b, and146c) as shown in step350may be countered by a servicing event where the system is reset or the processed signals170from the knock sensor(s) fall below a threshold or within a predetermined range. This threshold may vary depending on the machine type, placement of the knock sensor160, worksite attributes, and the type of differential lock, to name a few.

Preemptively disengaging the differential locks146using the input from the knock sensor160, rather than solely relying on the expiration of the disengagement timer, advantageously reduces instances where due to changing ground conditions and terrain the differential(s) being damaged or prematurely worn are further worn by turning (even slightly) with the differentials locked up and thereby extends the life use of the differential. Removing the conditional state of disengaging the automatic differential lock may also occur if the automatic differential lock conditions are no longer satisfied. The condition may include, but are not limited to, changing the steering angle176from turning to a straightforward direction, or a reduction in speed.

The controller148may further be programmed to command enable locking of the differential134as shown in step350responsive to a request to lock the differential (i.e. overriding the status of the differential lock based on the processed signals170from the knock sensor(s), and engagement conditions174being met).

The controller148may further be programmed to command enable locking of the differential responsive to a request to lock the differentials, engagement conditions174being met, and an expiration of the defined period as shown in step342.

The engagement conditions174include one or more a steering angle176and a speed178being less than a threshold.

The risk of differential wear is derived from a frequency182and an amplitude 184 of the processed signals170.

The controller148may further be programmed to store information190of the processed signals170indicating detected vibration abnormalities186and provide an alert188when the processed signals170indicating detected vibration abnormalities186exceed a threshold.

In an articulating work machine100, the front chassis102includes a front knock sensor160ato convert a sensed vibration167into electrical signals169for the front electronic differential lock146a, and a rear knock sensor160bcoupled to the trailer portion104wherein the rear knock sensor160bis configured to convert the sensed vibrations167into electrical signals169. A controller148is programmed to energize a locker to lock one of the front differential lock and the rear differential lock in response to a work machine speed178and steering angle176being less than a threshold.

The controller148is then programmed to receive and process the electrical signals169generated by the front knock sensor and the rear knock sensor, determine a risk of differential wear based on the processed signals170, and determine a risk of differential wear based on the processed signals170. The controller148is further programmed to deenergize the locker to unlock one of the front differential and the rear differential in response to signals indicative of worn differential locks, and inhibit locking of the differential for a defined period. The inhibition of locking may occur from inhibiting energizing of the differential lock.

The controller148may be further programmed to, responsive to an expiration of the defined period, command locking of the differential.

The controller148is further programmed to command locking of the differential responsive to a request to lock the differential, engagement conditions174being met, and expiration of the defined period.

The engagement condition174includes one of a work machine speed178and a steering angle176being less than a threshold. Work machine speed178and turning angle may have an impact on locking a differential. At higher speeds, the differential is more likely to remain unlocked to allow for smooth turning and maneuverability. Lock differentials may contribute to tire scrubbing and binding. When the work machine is moving slowly or when there is a high demand for traction, such as when driving off-road or on slippery surfaces, the differential may automatically lock to provide better traction to both wheels. The turning angle can also affect the engagement of the differential lock. In some work machines, the differential lock may disengage during sharp turns to allow for better macuverabiltiy. Overall, the engagement of the differential lock is included by work machine's speed178and turning angle to balance between traction and maneuverability.

The presence and severity of a risk of differential wear is derived from a frequency and an amplitude of the processed signals170. The control will analyze the processed signals170with defined thresholds and patterns to identify a racheting, jarring, or other vibration for preventing wear on a differential. The controller148continuously monitors the processed signals170. If an abnormal vibration persists, a trigger warning light may notify the operator, and the differential may lock before the time period initiated by the timer.

The controller148further stores information of the processed signals170indicating detected vibration abnormalities and provide an alert when the processed signals170indicating detected abnormalities exceed a frequency threshold.

In another embodiment, a method400of performing a predictive differential control on a work machine100is shown inFIG.4and comprises of the following steps. In step410, the method400includes receiving and processing historical electrical signal data196generated by the sensor (e.g. a knock sensor) associated with a presence or a severity of a sensed vibration167when the differential134is locked.

In step420, the method400includes extracting one or more features from the processed historical electrical signal data196wherein the one or more features is associated with the wear of the differential134.

In step430, the method includes training a predictive model using the one or more features and a labeled dataset regarding a health information of the differential lock.

In step440, the method includes applying the predictive model to the one or more features to generate a prediction of the health information of the differential lock.

In step450, the method includes unlocking the differential in response to a processed electrical signal170indicative of a risk of differential wear, and in step460inhibiting locking of the differential for a defined period that starts in response to the unlocking of the differential, wherein the defined period is based on the health information. A feature from the historical electrical signal data196comprises one or more of a steering angle176, and a speed178of the work machine100. In step470, the method400may further comprise storing information of the processed signals170indicating detected vibration abnormalities and providing an alert when the processed signals170indicating detected abnormalities exceeding a threshold. The controller148is further programmed to, responsive to expiration of the defined period, command locking the differential. The method400applies to one of a front electronic differential coupled to a front chassis and a rear electronic differential coupled to a rear chassis. The historical electrical signal data196comprises one or more of a frequency of the processed signals170, and an amplitude of the processed signals170. As such, a method400may be embodied as a program or algorithm operable on a controller148. It should be appreciated that the controller148may include any device capable of analyzing data from various sensors, comparing data, making decisions, and executing the required tasks.

By continuously monitoring and adjusting the differential lock conditions, the sensor advantageously helps maintain optimal performance and fuel efficiency while preventing damage due to ratcheting.

As used herein, “controller” is intended to be used consistent with how the term is used by a person of skill in the art, and refers to a computing component with processing, memory, and communication capabilities, which is utilized to execute instructions (i.e., stored on the memory or received via the communication capabilities) to control or communicate with one or more other components. In certain embodiments, the controller148may be configured to receive input signals in various formats (e.g., hydraulic signals, voltage signals, current signals, CAN messages, optical signals, radio signals), and to output command or communication signals in various formats (e.g., hydraulic signals, voltage signals, current signals, CAN messages, optical signals, radio signals).

The controller148may be in communication with other components on the work machine, such as hydraulic components, electrical components, and operator inputs within an operator station of an associated work machine. The controller148may be electrically connected to these other components by a wiring harness such that messages, commands, and electrical power may be transmitted between the controller148and the other components or wirelessly. Although the controller148is referenced in the singular, in alternative embodiments the configuration and functionality described herein can be split across multiple devices using techniques known to a person of ordinary skill in the art. The controller148includes the tangible, non-transitory memory on which are recorded computer-executable instructions, including a predictive maintenance for a track chain undercarriage algorithm. The processor of the controller148is configured for executing the predictive differential control algorithm.

The controller148may be embodied as one or multiple digital computers or host machines each having one or more processors, read only memory (ROM), random access memory (RAM), electrically-programmable read only memory (EPROM), optical drives, magnetic drives, etc., a high-speed clock, analog-to-digital (A/D) circuitry, digital-to-analog (D/A) circuitry, and any required input/output (I/O) circuitry, I/O devices, and communication interfaces, as well as signal conditioning and buffer electronics.

The one or more processors87train a predictive model420using the one or more features410, the historical inspection data430, and a labeled dataset480stored in memory85regarding an actual maintenance need or health information of the tracked undercarriage20. The features410, labeled datasets480, also referred herein collectively as training data420, may be received from, for example, multiple secondary users401. In some embodiments, the processors87generate the models using machine learning functions. Machine learning functions are generally functions that allow a computer application to learn without being explicitly programmed. In particular, a computer application performing machine learning functions is configured to develop an algorithm based on training data420. For example, to perform a supervised learning, training a predictive model420includes example inputs and corresponding desired outputs, and the processor progressively develops a model that maps input to the outputs470included in the training data420. Machine learning may be performed using various types of methods and mechanism including but not limited to decision tree learning, association rule learning, artificial neural networks, inductive logic programming, support vector machines, clustering, Bayesian networks, reinforcement learning, representation learning, similarity and metric learning, sparse dictionary learning, and generic algorithms.

Accordingly, the processor87in this example performs machine learning using the received training data (420,480) to train and develop a predictive model420that outputs a prediction or health information. Additionally, maintenance scheduling suggestions may shift depending on the after-market component type used, and the maintenance habits of the operator. The predictive model(s)420generated by the processor(s)87may be stored in a model database485in memory85. In some embodiments, the model database485is stored and transmitted from a cloud via a communication network, or external server. The model database485may be stored on a separate device specific to a worksite, an operator, a work machine, to name a few. Alternatively, or in addition to, the models generated by the processor87may be copied to one more separate devices such as databases external to the server. Secondary sources401of data from other machines may also serve as a predictive model420.

As used herein, “e.g.” is utilized to non-exhaustively list examples and carries the same meaning as alternative illustrative phrases such as “including,” “including, but not limited to,” and “including without limitation.” Unless otherwise limited or modified, lists with elements that are separated by conjunctive terms (e.g., “and”) and that are also preceded by the phrase “one or more of” or “at least one of” indicate configurations or arrangements that potentially include individual elements of the list, or any combination thereof. For example, “at least one of A, B, and C” or “one or more of A, B, and C” indicates the possibilities of only A, only B, only C, or any combination of two or more of A, B, and C (e.g., A and B; B and C; A and C; or A, B, and C).

Terms of degree, such as “generally”, “substantially” or “approximately” are understood by those of ordinary skill to refer to reasonable ranges outside of a given value or orientation, for example, general tolerances or positional relationships associated with manufacturing, assembly, and use of the described embodiments.

While the above describes example embodiments of the present disclosure, these descriptions should not be viewed in a limiting sense. Rather, other variations and modifications may be made without departing from the scope and spirit of the present disclosure as defined in the appended claims.