Braking intensity display

A display for a machine having a hydraulic brake is provided. The display includes a first display and a second display. The first display indicates a rate of heat accumulation within the hydraulic brake. The second display indicates a current temperature of the hydraulic brake.

TECHNICAL FIELD

The present disclosure relates to a temperature monitoring system for a brake on a machine, and more particularly to notifying an operator of an overheat condition of the brake.

BACKGROUND

Most construction machines while travelling downhill experience brake overheating while controlling the speed of the machine by resisting gravitational force. As a result of overheating of the brakes, the operator may have to pull over the machine to allow the brakes to cool down before reaching a desired destination. This results in a loss of productivity due to the time allowed for cooling of the overheated brakes.

The speed at which the machine is running downhill and the extent of brake usage and heating are interrelated factors. In order to allow the machine to run relatively fast downhill, heat accumulated within the brakes needs to be dissipated quickly. On the other hand, when operated slowly downhill, heat dissipation of the brakes may be stretched over a period of time. Typically, there exists a direct relationship between the downhill speed of the machine and the amount of heat accumulation within the brakes. However, although the machine's brakes may never overheat when operated too slowly, machine productivity may also be reduced to undesirable levels.

For example, U.S. Published Application Number 2003/0110849 discloses a method for monitoring the temperature of a friction brake to prevent overheating of the brake. The vehicle speed and brake activation time are monitored for braking event conditions known to add heat to the brake or brakes, and the frequency or rate of occurrence of these conditions is monitored. When the frequency of brake event conditions approaches a threshold value known to be approaching an over-temperature condition, the speed of the vehicle is limited in order to limit the amount of kinetic energy which can be absorbed by the brakes, thereby preventing the brakes from overheating.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a display for a machine having a hydraulic brake is provided. The display includes a first display and a second display. The first display indicates a rate of heat accumulation within the hydraulic brake. The second display indicates a current temperature of the hydraulic brake.

In another aspect, a method for indicating a rate of heat accumulation within a hydraulic brake of a machine is provided. The method receives a signal indicative of a current temperature of a hydraulic brake of the machine. The method also receives a signal associated with a brake command. The method determines a rate of heat accumulation within the hydraulic brake based, at least in part, on the received signals and a pre-determined allowable maximum temperature. The method displays the current temperature of the hydraulic brake and the determined rate of heat accumulation within the hydraulic brake.

DETAILED DESCRIPTION

FIG. 1illustrates an exemplary machine100, according to one embodiment of the present disclosure. More specifically, as shown in the accompanied figures, the machine100may embody a large mining truck102. It should be understood that the machine100may alternatively include an off-highway truck, a quarry truck, an articulated truck, a wheel tractor scraper, or any other suitable construction work machine.

Referring toFIG. 1, the large mining truck102may include a frame104. A material carrying dump body106may be pivotably mounted to the frame104. Further, an operator cab108may be mounted to the frame104, such as, e.g., above an engine enclosure110and on a front part of the frame104. The large mining truck102may be supported on the ground by a plurality of wheels112.

A person of ordinary skill in the art will appreciate that one or more engines (not shown) may be housed within the engine enclosure110. The engine may provide power to the wheels112and a final drive assembly, via a mechanical or electric drive train. In one embodiment, the large mining truck102may be configured to carry heavy loads downhill.

Speed of the machine100may be controlled by using a hydraulic brake and/or by applying resistive torque to the wheels112through the drive train. In one embodiment, the machine100may embody a mechanical drive machine. In this situation, there can be a physical connection between the engine, a transmission, a differential, and the wheels112. Hence, in the mechanical drive machine, retarding can be made possible by creating back-pressure in an exhaust manifold of the engine. This type of mechanical retarding applies resistive torque to the mechanical drive train.

In another embodiment, the machine100may also embody an electric drive machine. In this situation, the wheels112may be driven by an electric motor, such that the speed of the wheels112is controlled by the electric motor to either increase or decrease the wheel speed, as the case maybe. A person of ordinary skill in the art will appreciate that applying negative torque to the wheels112for decreasing the speed of the machine100may be referred to as dynamic braking or electrical retarding.

A variety of operator controls within the operator cab108and systems within the electronics of the machine100can be used to interface with the mechanical or electrical retarding system, and the hydraulic brake of the machine100. For example, one or more brake pedals, a governor/throttle pedal, a cruise control system, a throttle hold system, a backup throttle system, “retarder” levers, automatic retarder control software, and the like, can be used. It should be noted that any or all of these aforementioned controls may be used to input commands into the hydraulic brake and/or the mechanical or electrical retarding system.

Moreover, in case of both mechanical and electric drive machines, the mechanical or the electrical retarding, the hydraulic braking, or any combination thereof, can be controlled or actuated by electronics of the machine100. The machine100may include a retarding system201(either mechanical or electrical) and a hydraulic brake202as shown inFIG. 2. It should be understood that there may not necessarily be a direct physical linkage, between the operator controls provided within the operator cab108, such as, the brake pedal(s), and the retarding system201or the hydraulic brake202. For example, the brake pedal may communicate with the machine electronics, and the machine electronics may accordingly activate the retarding system201, the hydraulic brake202, or both as appropriate.

Activation and usage of the hydraulic brake202can influence the temperature of the fluid used within the hydraulic brake202. Overheating of the hydraulic brake202may result in a significant machine down time and may result in less efficient working operations. To this end, a controller208may be provided within the machine100and can be configured to determine a rate of heat accumulation within the hydraulic brake202. In one embodiment, the controller208can be coupled to a display210to indicate, to an operator, the rate of heat accumulation within the hydraulic brake202.

As shown inFIG. 2, a braking sensor204may be communicably coupled to the brake pedal associated with the hydraulic brake202. The braking sensor204may be configured to generate a signal indicative of a brake command. In one embodiment, the brake command may be indicative of the actuating force exerted by the operator or relative pedal position, thereby defining a degree of engagement of the brake pedal.

When the hydraulic brake202is used, kinetic energy is converted into heat. This heat may then be dissipated into the environment. A quantity of the heat may be stored within the hydraulic brake202, based on physical size and shape of the hydraulic brake202, quantity of fluid in the hydraulic brake202, and physical properties of materials used in the hydraulic brake202. As shown inFIG. 2, a first temperature sensor206may also be communicably coupled to the hydraulic brake202. The first temperature sensor206may be configured to generate a signal indicative of a current temperature of the hydraulic brake202. In one embodiment, as shown in the accompanied figures, the controller208may be communicatively coupled to the braking sensor204and the first temperature sensor206.

It should be understood that if the temperature of the hydraulic brake202exceeds a certain failure temperature, the hydraulic brake202may fail. This failure of the hydraulic brake202may include physical breakage of components of the hydraulic brake202, or a reduction in an amount of resistive force that the hydraulic brake202is capable of producing. The failure temperature can be pre-determined and a pre-determined allowable maximum temperature can therefore be calculated. The pre-determined allowable maximum temperature may generally include a safety factor and can therefore be lesser than the pre-determine failure temperature of the hydraulic brake202.

When the current temperature of the hydraulic brake202rises above the pre-determined allowable maximum temperature, the hydraulic brake202is said to overheat. In one embodiment, the controller208may be configured to determine the rate of heat accumulation within the hydraulic brake202, based on the current temperature of the hydraulic brake202, the pre-determined allowable maximum temperature, and the brake command.

The rate of heat accumulation within the hydraulic brake202may be indicative of a rate at which heat is added to the hydraulic brake202. Moreover, it should be noted that the current temperature of the hydraulic brake202is indicative of the temperature of the hydraulic brake202at a particular instant of time. However, the rate of heat accumulation may depict the change in temperature of the hydraulic brake202over a certain interval of time.

It should be understood that since some heat is stored within the hydraulic brake202, the change in temperature over time within the hydraulic brake202is not instantaneous. Rather, the temperature may build slowly or quickly depending on the rate at which heat is added or dissipated into the environment. The rate of heat accumulation within the hydraulic brake202may vary depending on a number of factors such as, but not limited to, the amount of resistive torque produced by the hydraulic brake202, the current temperature of the hydraulic brake202, the current environmental temperature, and the like.

Moreover in case of the electric drive machine, different braking zones may be defined based on the degree of engagement of the brake pedal, for example, a retard-only zone, a continuous zone, an intermittent zone, and the like. In one embodiment, the rate of increase in temperature within the hydraulic brake202may be based on the braking zone. For example, when the braking operation remains in the continuous zone, the rate of heat accumulation may be relatively negligible when compared to the braking operation reaches the intermittent zone. It should be understood that the rate of heat accumulation within the hydraulic brake202across the braking zone may vary non-linearly based on the degree to which the hydraulic brake202is applied, current temperature of the hydraulic brake202, and the like.

Referring toFIG. 2, the controller208may be communicably coupled to the display210. The display210may include an indicator light, a display gauge, a monitor, or any combination thereof, to alpha-numerically, graphically or otherwise visually and/or audibly notify the operator of information. Further, based on the rate of heat accumulation within the hydraulic brake202determined by the controller208, visual feedback may be provided to the operator via the display210. In one embodiment, the display210may include at least a first display and a second display as will be explained with reference to the remaining figures.

The first display may provide visual feedback to the operator to indicate the rate of heat accumulation within the hydraulic brake202in a variety of ways. For example, in case of the electric drive machine, the first display may include one or more zones corresponding to the different braking zones, such as, the retard-only zone, the continuous zone, the intermittent zone, and the like. The first display may be indicative of the build-up of heat within the hydraulic brake202in the currently activated zone.

Further, the second display may indicate the current temperature of the hydraulic brake202. The second display may include, for example, a dial, a temperature gauge, an alpha-numeric display panel, and the like. Based on a combined feedback provided by the first and second displays, the operator can be made aware of how much heat is being added to the hydraulic brake202and/or when an overheat condition of the hydraulic brake202may be reached. Accordingly, based on the combined feedback, the operator may be able to better utilize the hydraulic brake202. Better utilization of the hydraulic brake202may allow the operator to drive the machine100at an optimum speed at which control over the machine100is maintained and overheating of the hydraulic brake202is avoided.

In another embodiment, the display210may also include a third display to indicate an approximation of time remaining prior to overheating of the hydraulic brake202. The approximation of time remaining prior to overheating of the hydraulic brake202may allow the operator to ascertain how much time is left before the fluid in the hydraulic brake202increases in heat beyond the allowable maximum temperature. Also, the display210may include a fourth display for providing a warning indicative of an overheat condition of the hydraulic brake202. The warning may be provided by means of any suitable visual or auditory feedback. This warning may indicate to the operator that the hydraulic brake202will reach the overheat condition very soon.

In another embodiment, the display210may also indicate a maximum allowable speed of the machine100. The maximum allowable speed of the machine100may be indicative of the speed at which the machine100needs to be driven in order to reach the destination without causing the hydraulic brake202to overheat and thereby increasing machine productivity. Also, the display210may indicate a maximum braking force that can be applied by the operator without causing the hydraulic brake202to overheat. Various exemplary displays will be explained in connection withFIGS. 3-6.

Since the weight of the load carried by the machine100may change for each cycle, it may be difficult to predict a fixed speed of the machine100for avoiding overheating the hydraulic brake202. Hence, in one embodiment, the controller208may include a mapping module209configured to record a travel history of the machine100. The mapping module209may either be intrinsic or extrinsic to the controller208. The mapping module209may be coupled to other sensors, such as, for example, a tire pressure sensor, a second temperature sensor, an inclinometer, and the like.

In one embodiment, the tire pressure sensor may generate a signal indicative of a current pressure of the wheels112of the machine100based on the weight of the load being carried by the machine100. Further, the second temperature sensor may be configured to generate a signal indicative of an ambient temperature. The inclinometer may generate a signal indicative of a degree of inclination of the machine100. The mapping module209may receive and monitor one or more signals received from any of the above-mentioned sensors.

In another embodiment, the controller208and/or the mapping module209may be coupled to a database or data storage and retrieval structure. The database may be intrinsic or extrinsic to the controller208and/or the mapping module209. The database may be configured to store travel history of the machine100based on the received one or more signals, such as, e.g., during load and unload cycles of the machine100. In another embodiment, the controller208and/or the mapping module209may be configured to retrieve and to plot as a map the one or more received signals. A person of ordinary skill in the art will appreciate that the monitored one or signals may provide a predictive analysis of overheating of the hydraulic brake202over time based on load carried by the machine100, position of the machine100, and the like.

Further, in one embodiment, the controller208may adjust a braking response of the machine100based on the mapped travel history. For example, the controller208may adjust the braking response by issuing control signals to the hydraulic brake202, and modulating the braking force. In another example, the controller208may determine the maximum allowable speed of the machine100based on the travel history recorded by the mapping module209. A person of ordinary skill in the art will appreciate that other sensors not mentioned herein may also be utilized to determine and plot as a map the travel history of the machine100.

FIG. 3depicts one exemplary visual feedback provided to the operator of the electric drive machine. As shown inFIG. 3, a second display302can include a braking temperature gauge303to indicate the current temperature of the hydraulic brake202. The first display304may provide an indication of the rate of heat accumulation within the hydraulic brake202.

In one embodiment, the first display304may include one or more zones. In this case, the one or more zones of the first display304may correspond to the retard-only zone306, the continuous zone308, the intermittent zone310, and the maximum (‘max’) zone312respectively. The retard-only zone306is associated with the activation of the retarding system201. On the other hand, the continuous and intermittent zone308,310are associated with the activation of the hydraulic brake202. The ‘max’ zone312is indicative of a maximum braking force applied when the operator engages the brake pedal to the maximum extent possible. It should be noted that other zones may also be included to indicate various combinations of braking operations.

The rate of heat accumulation may be associated with the activation of the hydraulic brake202, and may be independent of the braking activated by the retarding system201. For example, in case the braking is occurring in the retard-only zone306, then the hydraulic brake202is inactive and hence the time remaining prior to overheating of the hydraulic brake202may be infinite in this case.

In one embodiment, a third display314indicative of the approximation of time remaining prior to overheating of the hydraulic brake202may be provided. As can be seen inFIG. 3, a first time period, such as, e.g., 5 minutes, is remaining prior to the overheating of the hydraulic brake202of the machine100. Other time periods may be included. Also, in this case, the first display304indicates that the hydraulic brake202is currently in the intermittent zone308. Based on the feedback provided by the display210, the operator may be notified that the current temperature of the hydraulic brake202is within a suitable range. Also, the operator may be notified that the hydraulic brake202is activated and that based on the rate at which heat is being added within the hydraulic brake202, about 5 minutes is remaining prior to the hydraulic brake reaching the overheat condition. Accordingly, the operator may manually alter the braking force applied in a suitable manner in order to allow the machine100to reach the destination without overheating the hydraulic brake202.

FIGS. 4A,4B,4C depict another set of exemplary displays at different instants of time. Three zones on a dial can be indicative of the retard-only zone306, the continuous zone308, and the intermittent zone310, respectively. Less or more zones may be displayed. Referring toFIG. 4A, the operator is notified by a braking force display402of the braking force currently being applied, such as about 73 kN as shown. In one embodiment, one example of the second display may include a temperature display404. In this case, the temperature display404indicates to the operator of the current temperature of the hydraulic brake202, such as, e.g., about 94° C. as shown.

The visual feedback provided to the operator may indicate that the braking is currently occurring in one of the zones, such as, e.g., the retard-only zone306. Based on the rate of heat accumulation within the hydraulic brake202determined by the controller208, the operator may be notified of the time remaining prior to overheating of the hydraulic brake202at a time display406. In this case, the operator is notified that about a period of 6 minutes and 23 seconds is remaining prior to overheating of the hydraulic brake202.

FIG. 4Bdepicts the display provided to the operator at another instant of time. In this exemplary case, the operator is notified by the braking force display402that the braking force being applied is about 262 kN. The current temperature of the hydraulic brake202is shown to be about 170° C., as indicated at the temperature display404. The current braking operation is shown in the continuous zone308. Also, the operator is notified by the time display406that the time remaining prior to overheating of the hydraulic brake202is about 9 seconds. In yet another exemplary case depicted inFIG. 4C, the operator is notified that the current temperature of the hydraulic brake202is about 49° C. by the temperature display404, and that the braking force is about 11 kN by the braking force display402. As shown in the visual feedback, infinite time is remaining prior to overheating of the hydraulic brake202, as indicated by the time display406.

The exemplary visual feedbacks shown inFIGS. 5A,5B,5C notify the operator of the degree of activation of the hydraulic brake202of the machine100by a brake activation display502, and the time remaining prior to overheating of the hydraulic brake202by a time display504. InFIG. 5A, the operator is notified at the brake activation display502that the braking force is about 80 kN. Also, a period of about 3 minutes and 27 seconds is remaining prior to the overheating of the hydraulic brake202, as indicated at the time display504.

InFIG. 5B, the braking force is about 220 kN, as indicated at the brake activation display502. Also, the operator is notified that about 17 seconds is remaining prior to the overheating of the hydraulic brake202, as indicated at the time display504.FIG. 5Cdepicts that infinite time is remaining prior to overheating of the hydraulic brake202, as indicated at the time display502. This can be due to the low hydraulic braking force of about 21 kN, as indicated at the brake activation display502.

FIGS. 6A,6B,6C depict yet another exemplary set of visual feedback provided to the operator. In this case, the fourth display including a warning light602is provided. InFIG. 6A, the operator is notified by a brake display604that a current braking load of the hydraulic brake is about 78%. The operator is also notified that a period of about 2 minutes and 17 seconds is remaining prior to overheating of the hydraulic brake, as indicated at a time display606. InFIG. 6B, due to the low braking load of about 11%, as indicated at the braking display604, an infinite time is remaining prior to overheating of the hydraulic brake202. Hence, the warning light602is deactivated. However, inFIG. 6C, only about 12 seconds is remaining prior to the overheating of the hydraulic brake202, as indicated at the time display606and hence the warning light602is activated in order to alert the operator.

The visual feedbacks described herein are merely examples and do not limit the scope of this disclosure. It should be noted that the values shown on the displays are exemplary. Also, other such similar visual and/or auditory feedback to notify the operator of the rate of heat accumulation within the hydraulic brake202and/or time remaining prior to overheating of the hydraulic brake202may be utilized without deviating from the scope of this disclosure.

The controller208may embody a single microprocessor or multiple microprocessors that include a receiver for receiving signals from the one or more sensors and providing output to the display210. Numerous commercially available microprocessors may be configured to perform the functions of the controller208. It should be appreciated that the controller208may readily embody a general machine microprocessor capable of controlling numerous machine functions. The controller208may include memory and may access the memory in order to retrieve stored data. Moreover, the controller208may be capable of performing mathematical operations required for the computation of the rate of heat accumulation within the hydraulic brake202, time remaining prior to overheating of the hydraulic brake202and/or maximum allowable speed of the machine100, as well as other machine data.

A method700for notifying the operator of the rate of heat accumulation within the hydraulic brake202of the machine100will be explained in connection withFIG. 7.

INDUSTRIAL APPLICABILITY

Overheating of the hydraulic brake202during downhill travel of the machine100may cause the hydraulic brake202to become markedly ineffective. As a result, the operator is signaled to pull over the machine100so that the hydraulic brake202can cool down. There is an increased risk for time wasted while waiting for the hydraulic brake202to cool down, thereby causing a loss of machine productivity.

A theoretical best case for carrying a large load down a decline is to operate the machine100at as high of a speed as possible without overheating the hydraulic brake202at any time during the downhill cycle. In the case of a steep grade, the machine100should be operated such that the pre-determined allowable maximum temperature of the hydraulic brake202is reached just as the machine100reaches the base or bottom of the decline.

On reaching the bottom of the decline the hydraulic brake202may no longer be needed to control speed of the machine100. This method of operation may produce a relatively low cost/ton to a customer. However factors like grade of a downward cycle, length of a downward slope, environmental temperature, load carried by the machine100, may vary. Therefore, the desired speed at which the machine100may be safely operated can vary widely from site to site, from day to day, and from one load to the next.

Based on the feedback of the currently used displays, the operator may determine if the current temperature of the hydraulic brake202lies outside of a determined safe range. Further, with the feedback provided by the currently used braking displays, the operator may be unable to judge the speed at which machine100needs to be driven in order to reach the destination without overheating the hydraulic brake202. Also, the operator may be unaware of the time remaining prior to overheating of the hydraulic brake202, since the rate of heat accumulation within the hydraulic brake202may be unknown. Hence, in order to avoid reaching the overheat condition of the hydraulic brake202, the operator may run the machine100at a much slower speed than the machine100can withstand, causing an increased cycle time and affecting the overall productivity.

The present disclosure, as described above, can directly provide feedback of the rate of heat accumulation within the hydraulic brake202which can be beneficial to the operator of the machine100. The visual feedback provided to the operator by the display210may allow the operator to better utilize the hydraulic brake202based on the rate of heat accumulation within the hydraulic brake202. This may allow the operator to judge the maximum allowable speed for running the machine100so that the destination can be reached without overheating the hydraulic brake202. This in turn will decrease cycle time of the machine100and therefore increase productivity (tons/hr) and decrease operating costs (cost/ton).

FIG. 7illustrates the method700for notifying the operator of the rate of heat accumulation within the hydraulic brake202in the machine100. At step702, the signal indicative of the current temperature of the hydraulic brake202may be received by the controller208. The signal associated with the brake command may be received from the braking sensor204at step704. Subsequently, at step706, the controller208may determine the rate of heat accumulation within the hydraulic brake202based on the received signals and the pre-determined allowable maximum temperature of the hydraulic brake202.

For example, the controller208may determine the rate of heat accumulation within the hydraulic brake202based on the change in the temperature of the hydraulic brake202over a fixed period of time, by computing a difference in temperature readings of the hydraulic brake202. In another example, the determined rate of heat accumulation within the hydraulic brake202may also be based on a pre-determined increase in temperature associated with the braking zone. Moreover, in another embodiment, the controller208may compute the approximate time remaining prior to overheating of the hydraulic brake202based on the rate of heat accumulation within the hydraulic brake202and the time it will take to reach to the allowable maximum temperature of the hydraulic brake202if heat is added to the hydraulic brake202at the determined rate.

At step708, the current temperature of the hydraulic brake202and the determined rate of heat accumulation within the hydraulic brake202may be displayed. As described above, the display210coupled to the controller208may provide the notification to the operator. In one embodiment, the display210may indicate the time remaining prior to overheating of the hydraulic brake202. Also, the display210may indicate the maximum allowable speed at which the machine100needs to be driven to reach the destination without causing the hydraulic brake202to overheat. The determination of the maximum allowable speed of machine100may be based on the rate of heat accumulation within the hydraulic brake202. Exemplary visual feedbacks are shown inFIGS. 3-6.

In one embodiment, the mapping module209may receive one or more signals from at least one of a tire pressure sensor, a second temperature sensor and an inclinometer. The mapping module209may monitor the one or more received signals. Moreover, the mapping module209may be configured to map the travel history of the machine100based on the monitored one or more signals. In another embodiment, the controller208may adjust the braking response of the machine100based on the mapped travel history of the machine100.

A person of ordinary skill in the art will appreciate that based on the feedback provided by the display210the operator is made aware of the current temperature of the hydraulic brake202and also the rate of heat accumulation within the hydraulic brake202. Hence, the operator may accordingly determine whether or not to apply the braking force such that slightly prior to overheating of the hydraulic brake202, the machine100completes its descent or reaches the bottom of the hill. In one embodiment, the mapping module209may map the travel history of the machine100on a regular basis, such as a daily basis. In another embodiment, based on the mapped travel history, the controller208may begin to predict where the machine100is, and modulate the speed and/or braking accordingly to allow the machine100to reach the destination without overheating the hydraulic brake202.

It should be noted that the disclosure may be utilized on the mechanical drive machines and/or the electric drive machines. More specifically, the disclosure may be utilized in relatively large construction machines which are capable of moving rapidly downhill. For example, the display210may be used in the large mining truck102that is capable of carrying loads of up to about 400 tons. It will apparent to one of ordinary skill in the art that the visual feedback provided to the operator by the controller208may be most beneficial in this case. In one embodiment, the display210may also be utilized on other machines such as, for example, quarry and other similar construction trucks that are capable of carrying loads of up to about 100 tons, and also on machines like the articulated truck which can carry loads of up to about 40 tons.