Track adjust monitor

A work machine includes a frame assembly supporting an idler and a drive sprocket. A track is looped around the idler and the drive sprocket. A track-adjust mechanism is configured to extend and to retract the frame assembly to adjust a tension of the track. A position sensor is configured to measure an extension of the track-adjust mechanism. A controller is configured to receive an extension measurement from the position sensor, determine a track tension based on the extension measurement, and output a track tension signal.

TECHNICAL FIELD

The present disclosure generally relates to track work machines having a drive track, and more particularly, relates to a track adjustment monitor for a drive track of a work machine.

BACKGROUND

Work machines often include an undercarriage assembly having a track to propel the work machine about a work site. The track includes a plurality of interconnected linkages that form a continuous loop. The track extends around a plurality of rollers and idlers and is driven by a drive sprocket to rotate the track. The work machines may include a plurality of tracks, for example a left-side track and a right-side track, each capable of receiving drive inputs from separate drive sprockets to maneuver the work machine about the work site.

The undercarriage assembly further serves as a suspension system to provide for proper absorption of shocks to the remainder of the work machine, and may further include a track-adjust mechanism to extend and retract a frame assembly and a recoil assembly. The operation of the track-adjust mechanism and the recoil assembly affects the tension of the track on the work machine.

Maintaining a proper track tension is one factor to extending an operational life of the work machine and to ensure proper operation of the work machine. Varying factors can affect the track tension, from wear of components to debris being stuck within the track and roller assemblies.

Typically, monitoring the track tension is a manual procedure, performed by an operator. However, the operators require training in order to properly assess the track tension. Further, periodic assessment of the track tension may not occur as regularly as desired.

U.S. Pat. No. 6,276,768 describes a track tensioning assembly for adjusting tension on a drive track chain on the undercarriage assembly of a work machine. The undercarriage assembly also includes a first hydraulic actuator mechanically coupled to the first drive track chain to adjust tension on the first drive track chain and a second hydraulic actuator mechanically coupled to the second drive track chain to adjust tension on the second drive track chain. The undercarriage assembly further includes a slack adjuster assembly. The slack adjuster assembly has (i) an adjuster housing defining (a) a main chamber, (b) a fluid inlet, (c) a first fluid outlet which is fluidly coupled to the first hydraulic actuator, and (d) a second fluid outlet which is fluidly coupled to the second hydraulic actuator, (ii) a first piston positioned in the main chamber, the first piston selectively couples the fluid inlet to the first fluid outlet, and (iii) a second piston positioned in the main chamber, the second piston selectively couples the fluid inlet to the second fluid outlet.

While effective, there is still a need for improved or alternative strategies for monitoring track tension of a work machine.

SUMMARY

In accordance with one aspect of the present disclosure, a work machine includes a frame assembly to support an idler and a drive sprocket. A track is looped around the idler and the drive sprocket. A track-adjust mechanism is configured to extend and to retract the frame assembly to adjust a tension of the track. A position sensor is configured to measure an extension of the track-adjust mechanism. A controller is configured to receive an extension measurement from the position sensor, determine a track tension based on the extension measurement, and output a track tension signal.

In another embodiment, a work machine includes a frame assembly supporting an idler and a drive sprocket, a track looped around the idler and the drive sprocket, and a track-adjust mechanism configured to extend and to retract the frame assembly to adjust a tension of the track. A recoil system, or a recoil assembly, having a recoil spring is included to bias against the track-adjust mechanism. A spring tension sensor is configured to measure a spring tension of the recoil spring. Further, a controller is configured to receive a spring tension measurement from the spring tension sensor, determine a track tension based on the spring tension measurement, and output a track tension signal.

In yet another embodiment a track monitoring system for a work machine having a track is provided for. The track monitoring system includes a controller configured to receive a position measurement indicative of an extension of a track-adjust mechanism that extends and retracts a frame assembly to adjust a tension of the track, determine a track tension of the track based on the received extension measurement, and output a track tension signal.

These and other aspects and features of the present disclosure will be more readily understood when read in conjunction with the accompanying drawings.

DETAILED DESCRIPTION

Referring now to the drawings, and with specific reference toFIG.1of a work machine in accordance with an embodiment of the present disclosure, is generally referred to by reference numeral102. While the work machine102depicted is a track type tractor, it is be understood any number of types of track driven work machines, including but not limited to, excavators, cold planers, loaders, dozers, forestry machines, mining machines, and the like can include the teachings of the present disclosure with equal efficacy.

In particular,FIG.1depicts the side elevation view100of the work machine102. The work machine102may be employed to perform a variety of functions such as earth moving and ripping. The work machine102includes a plurality of work implements120, depicted as an exemplary hydraulically-powered ripper on the rear of the work machine102and a blade assembly on the front of the work machine102. However, various other work implements120may be utilized without deviating from the scope of the present disclosure.

The work machine102may include an engine124, which may be realized as a diesel engine, a spark ignition engine, a liquid natural gas engine, an electric engine, or the like. The engine124serves as a source of power for the various systems (e.g., hydraulic, auxiliary electric) of the work machine and also provide for propulsion.

The work machine102further includes an undercarriage assembly118. The undercarriage assembly118includes a frame assembly104, a drive sprocket110, a front idler wheel106, a rear idler wheel108, and a plurality of roller assemblies122. A track112is looped around the idlers106,108and the drive sprocket110. The drive sprocket110drives the track112around the front idler wheel106, the rear idler wheel108, and the plurality of roller assemblies122to provide a motive power for the work machine102. In particular, the mechanical output of the engine124is transmitted to the drive sprocket110via a transmission assembly (not shown) thereby driving the drive sprocket110to advance the track112. The work machine102is depicted on a ground surface126and for reference, the work machine102may be propelled in a forward direction128or a reverse direction130by selective rotation of the drive sprocket110. It should be noted that the right-side of the work machine102is depicted in the view100, and that a work machine102may include a similar undercarriage assembly118on the left-side of the work machine102.

The work machine102further includes an operator station114. The operator station114is provided to enclose or otherwise house the devices associated with the work machine102, although certainly a non-enclosed operator station114may be utilized. The operator station114may include a seat for an operator, controls to operate the work machine102, displays and indications to inform the operator of the status of the work machine, and the like. In other embodiments, the work machine102is a remotely operated or autonomous work machine. In such embodiments, the work machine102may not include an operator station on the work machine, but a remote operator station or control station. The remote operator station may be communicatively coupled to the work machine via a wired or wireless network and be able to receive status updates regarding operations of the work machine102.

FIG.2is an enlarged side elevation view of the undercarriage assembly of the work machine ofFIG.1, in accordance with an embodiment of the present disclosure. In particular,FIG.2depicts the side elevation view200of the undercarriage assembly118of the work machine102fromFIG.1. The frame assembly104includes a front member202and a rear member204. The front member202is able to move relative to the rear member204, in directions parallel to the forward direction128and the reverse direction130, based on operations of a track-adjust mechanism322and the recoil assembly302, discussed more in detail below. The track-adjust mechanism322may set a nominal tension of the track112, but under operation of the work machine102, the track-adjust mechanism322and the recoil assembly302may work in tandem to adjust the tension of the track112. Various operational conditions, such as dirt packing, mode of the drive train, slope of the ground surface, and the like, may cause the track tension to vary. In brief, extension and retraction of the track-adjust mechanism322, as well as extension and retraction of the recoil assembly302, causes the frame assembly104to extend and to retract to adjust the tension of the track112.

In some embodiments, the track-adjust mechanism322is realized by a hydraulic cylinder, and may be referred to as a track-adjust cylinder. In other embodiments, the track-adjust mechanism is either one of an electric or a mechanical linear actuator configured to extend and retract to adjust the track tension.

The front idler wheel106is supported by the front member202and the rear idler wheel108is similarly supported by the rear member204. The drive sprocket110may be similarly fixed to either one of the front member202or the rear member204. As it is depicted inFIG.2, the drive sprocket110is fixed and supported by the rear member204. The track112is looped around the front idler wheel106, the rear idler wheel108, and the drive sprocket110, as well as the roller assemblies122.

The view200includes reference points206and208, and a reference line210that extends between these reference points. At area214, it is visible that the track112sags, as indicated by the distance212between the track112and the reference line210. With an increased track tension (e.g., by extending the track-adjust mechanism322and moving the front member202apart from the rear member204) the distance212will become smaller. Conversely, with a decreased track tension (e.g., by retracting the track-adjust mechanism322and moving the front member202closer to the rear member204), the distance212will become larger.

FIG.3is an internal view of a portion of the frame assembly ofFIG.2, in accordance with an embodiment of the present disclosure. In particular,FIG.3depicts the internal view300of a portion of the frame assembly104. The portion of the frame assembly104is oriented the same as depicted in the views100and200ofFIGS.1and2, respectively, with the front member202being located on the right side and the rear member204being located on the left side of the view300. The track-adjust mechanism322is configured to extend and retract to change an extension308between a fixed portion of the front member202and a fixed portion of the rear member204. A position sensor310may be configured to measure the extension308of the track-adjust mechanism322. Although various position sensors310are described herein, the position sensor310measures a distance between a fixed portion of the front member202and a fixed portion of the rear member204. For example, the track-adjust mechanism322may include a front flange318and a rear flange320that move relative to each other upon extension and retraction of the track-adjust mechanism322. Thus, measuring a distance between the front flange318and the rear flange320provides an indication of the extension308.

In some embodiments, the track-adjust mechanism322is a hydraulically operated cylinder. In such embodiments, a working pressure of the track-adjust mechanism322may be obtained. For example, a pressure sensor314may be affixed to an access port316that is fluidly connected to the hydraulic fluid within the track-adjust mechanism322.

In some embodiments, the frame assembly104includes a recoil assembly302. The recoil assembly302includes a recoil spring304is under tension and is positioned to bias a portion of the track-adjust mechanism322away from the rear member204. The recoil spring304is positioned such that it exerts a force against the rear member204and a portion of the track-adjust mechanism322, such as the rear flange320. The recoil spring304may thus be under a compression force and exert opposing forces towards the rear member204and the rear flange320. In some embodiments, a recoil assembly tension sensor312is configured to measure a recoil assembly tension. The recoil assembly tension sensor312may be realized as a strain gage disposed on the recoil spring. In other embodiments, the recoil assembly tension sensor312may be realized as a load sensor324that is disposed between the recoil spring304, or similar component, and the frame assembly104such that the load sensor is able to measure the force exerted by the recoil spring304. As depicted in the view300, the load sensor324is disposed between the rear member204and the recoil spring304. Further, strain gages on the recoil spring304or on the track-adjust mechanism322may further be configured to serve as the load sensor324. Such strain gages are calibrated to determine an axial load on either one of the recoil spring304or the track-adjust mechanism322to determine a load.

In other embodiments, the recoil assembly302may be a gas-compressed cylinder, or it may include a compressed gas cylinder operating in parallel or series with a recoil spring to adjust the track tension. The recoil assembly302may act similar to the recoil spring304and may further include a recoil assembly tension sensor that is configure to measure a recoil assembly tension, similar to the recoil spring tension.

The recoil assembly302may further include a twist resistor306to adjust a tension of the recoil spring304. The front member202of the frame assembly104is able to move relative to the rear member204of the frame assembly104. The twist resistor306serves to constrain a rotational degree of freedom so that either the front member202or the rear member204does not rotate relative to each other. The twist resistor306may include a key and rail system that a portion of the front member202slides along relative to the rear member204. In some embodiments, overextension of the track-adjust mechanism322may cause increased wear or damage to the twist resistor306by preventing the key and rail system from properly engaging.

FIG.4is a block diagram of a track monitoring system, in accordance with an embodiment of the present disclosure. In particular,FIG.4depicts components of the track monitoring system400and includes a controller402. The controller402is configured to receive, from the position sensor310, an extension measurement; from the recoil assembly tension sensor312a recoil assembly tension measurement406; and from the pressure sensor314a track-adjust mechanism pressure measurement408. The controller402may further receive a drive signal410. The drive signal410is indicative of the drive sprocket110being rotated to cause the work machine102to proceed in a forward or a reverse direction.

The controller402is programmed to determine a track tension based in part on the received measurements. For example, the track tension may be based on any one of the extension measurement404, the recoil assembly tension measurement406, and the track-adjust mechanism pressure measurement408. In some embodiments, the track tension is based on a one or more of the measurements. For a given circumferential measurement of the track112, an extension308of a track-adjust mechanism may be related to a track tension. Further, the track-adjust mechanism pressure measurement408and the recoil assembly tension measurement406may also both be related to the track tension as they both indicate the relative force being applied to the frame assembly104to separate the front member202from the rear member204.

The controller402may be realized by electrical components commonly found in other work machine controllers and may include a microprocessor424, a memory device426, and an interface circuit428. The interface circuit428is configured to receive the various signals (e.g., measurements404-408, and drive signals410), and is further configured to output signals (e.g., a track tension signal412) to various devices. As depicted inFIG.4, the various output devices may include an operator display414, a wireless communication device416, a diagnostic code reader418, a warning light420, and a Short Message Service (SMS) interface422, and the like. For example, the interface circuit428may output the track tension signal412to the operator display414to display a track tension indication. In another example, the track tension signal may be output via the wireless communication device416to a remote user. In some embodiments, the determined track tension is compared to an allowable track tension range. In such an embodiment, the track tension may only be output (e.g., as an alert) responsive to the determined track tension being outside of the allowable track tension range.

In some embodiments, the controller402may be configured to compare the extension measurement404to a predetermined extension threshold to determine if the track-adjust mechanism is in an204overextension condition. In embodiments with a twist resistor306, the frame assembly104may experience increased wear or potential for damage when operated in an overextension condition. Responsive to determining that the extension measurement404exceeds the predetermined extension threshold, the controller402may output an overextension signal, similar to the track tension signal412. The overextension signal may cause a warning light to display at the operator station, cause an audible alarm to sound at a location of the track-adjust mechanism322adjustment point, or send an alert to a remote party to indicate that the track-adjust mechanism322is in an overextension condition.

In some embodiments, the controller402is configured to detect a measurement sequence that is based in part on the drive signal410. The tension of the track is dependent upon many different variables, including the mode of propulsion of the work machine102(operating forwards or backwards, power train loads as determined by an engine output or loads measured at drive shaft or in the transmission, and the like), and the slope of the ground surface126. The controller402may detect the desired conditions to perform a track tension determination. In some embodiments, the work machine102further includes an inclinometer to determine the slope of the ground surface126. The measurement sequence may further define a maximum slope of the ground surface126to satisfy the conditions to be a successful track tension determination. Responsive to detecting the measurement sequence, the controller402determines the track tension. In other embodiments, the controller402is configured to receive a slope measurement from the inclinometer and adjust a determined track tension based on the received slope measurement. In such an embodiment, the controller402is able to factor out the effect on track tension caused by the slope of the ground surface to determine a nominal (e.g., track tension when work machine102is on a level ground surface) track tension measurement.

FIGS.5-7depict a plurality of different position sensors310installed onto a track-adjust mechanism322. In each of theFIGS.5-7, the front member202is positioned on the right side of the figure and the rear member204is positioned on the left side of the figure. For reference, the distance506is measured between the front flange318and the rear flange320and this distance506may serve as the extension308as depicted in the view300ofFIG.3.

FIG.5is perspective view of a portion of a track-adjust mechanism having a first position sensor, in accordance with an embodiment of the present disclosure. In particular,FIG.5depicts the view500of the optical sensor502serving as the position sensor310within the track-adjust mechanism322. The optical sensor502is affixed to the front flange318and is oriented to determine a distance506between the front flange318and the rear flange320. This extension measurement504, obtained by the optical sensor502, may be provided to the controller402to determine the track tension.

FIG.6is perspective view of a portion of a track-adjust mechanism having a second position sensor, in accordance with an embodiment of the present disclosure. In particular,FIG.6depicts the view600of the position sensor310being a magnetic position measurement system602. The magnetic position measurement system602includes an attachment point604that is configured to attach to a portion of the frame assembly that is fixed relative to the front member202. An extension arm608extends from the attachment point604and includes a magnetic sensor606on the distal end of the extension arm608. The magnetic sensor606is configured to detect a position of a portion of the frame assembly104that is fixed relative to the rear member204. Here, the attachment point604is attached to the front flange318and the magnetic sensor606is positioned to detect the position of the rear flange320relative to the front flange318. This measurement obtained by the magnetic position measurement system602may be provided to the controller402to determine the track tension.

FIG.7is perspective view of a portion of a track-adjust mechanism having a third position sensor, in accordance with an embodiment of the present disclosure. In particular,FIG.7depicts the view700of the position sensor310being a string measurement system702. The string measurement system702includes a string706that is affixed to the rear flange320at the attachment point708. The string retractor704is affixed to the front flange318and is configured to exert a tension on the string706to retract the string706into the string retractor704. The string retractor704is configured to determine the extension measurement based on the length of the string706that is outside of the string retractor704. This measurement obtained by the string measurement system702may be provided to the controller402to determine the track tension.

INDUSTRIAL APPLICABILITY

In general, the teachings of the present disclosure may find applicability in many industries including, but not limited to, construction, agricultural, mining, industrial, commercial, transportation, or marine applications. More specifically, the teachings of the present disclosure may find applicability in any industry relying on track-type propelled machines. Example work machines102may include bulldozers, cranes, cold planer machines, and the like. Further, the track-type work machines may operate in a variety of ground terrain conditions that may affect the track tension in varying ways throughout the operational life of the work machine.

FIG.8is a flowchart of a series of steps that may be involved in determining a track tension, in accordance with an embodiment of the present disclosure. In particular,FIG.8depicts the method800that includes detecting a measurement sequence at block802, receiving measurements at block804, determining a track tension at block806, and outputting a track tension signal at block808. Although presented in sequence, it is expected that one with skill in the art may perform the limitations of the various blocks in a different sequence than that depicted inFIG.8.

The method800is used in conjunction with the track monitoring system400ofFIG.4by way of an example. The track monitoring system400may be included on the work machine102ofFIG.1, although any similar track-type machine may be used. The work machine102may be equipped with any of the varying sensors disclosed herein. For example, the work machine102may include any one of or a combination of the position sensor310, the recoil assembly tension sensor312, and the pressure sensor314to determine the track tension. Further, the work machine may include any one of the various ways to output the track tension signal412. Selection of the various sensors and methods of outputting the track tension signal may be based in part on the expected operating characteristics of the work machine102. For example, an optical sensor502serving as the position sensor310may provide an accurate extension measurement404. However, the optical sensor502may not operate as effectively in dusty work site environments, and a string measurement system702or a magnetic position measurement system602may be preferred systems for obtaining the extension measurements404.

In an example embodiment, the work machine102is operating on a work site. At block802, the controller402receives the drive signals410indicative of the operation of the drive sprocket110. Upon detecting that the work machine102is in a measurement sequence, the controller402may then determine the track tension. In some embodiments, the prerequisite that the work machine102be on a level surface is included in detecting the measurement sequence.

At block804, the controller402receives the measurements. For example, it may receive any one of or all of the extension measurement404from the position sensor310, the recoil assembly tension measurement406from the recoil assembly tension sensor312, and the track-adjust mechanism pressure measurement408from the pressure sensor314. Based on any one of or a combination of these measurements, the controller402determines the track tension. In some embodiments, the track tension is output at all times. In other embodiments, the track tension is output only if certain conditions are met (e.g., the track tension being out of a defined range).

At block808, the controller402outputs the track tension signal412. Outputting the track tension signal412may cause an indication to display on an operator display414, be transmitted via a wireless communication device416, output a diagnostic code to418to a diagnostic code reader, illuminate a warning light420, or cause the transmission of a SMS text message422.

In some embodiments, the track tension signal may be aggregated over time to perform a longevity analysis of the undercarriage assembly118. The aggregated track tension data may be further combined with geographic and terrain data to develop manufacturer-recommend track tension settings to improve the longevity of the undercarriage assembly118when operating in particular geographic areas or areas with known terrain types.

In yet other embodiments, the aggregated track tension data may be analyzed by machine learning to detect operating trends of the work machine102that affect the performance of the work machine102. Updated track-tension ranges may be developed responsive to the machine learning analysis.