Patent Publication Number: US-8972149-B2

Title: Control system implementing derate based on air characteristics

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to a control system and, more particularly, to a control system for a mobile machine that implements engine derate based on an environmental air characteristic. 
     BACKGROUND 
     Machines such as, for example, haul trucks, drills, loaders, conveyors, and other types of heavy equipment are commonly used in underground mining applications to perform a variety of tasks. Some of these tasks involve carrying or pushing material through long tunnels that have environmental conditions that vary along their lengths. These environmental conditions can include, among other things, a low quality or low supply rate of air found at mid-portions of the tunnels. When passing through these tunnels, care should be taken such that the conditions at the mid-portions do not cause machine malfunctions or create situations unsuitable for prolonged human occupation. One precaution currently implemented includes manually reducing machine performance in certain tunnel sections such that the environmental conditions in those sections do not degrade below acceptable levels. Another precaution includes banning certain machines from particular tunnel sections. Both of these precautions are undesirable, however, as they tend to increase operator responsibility, generate opportunities for error, and lower productivity. Accordingly, another way to account for varying environmental conditions in particular work zones is desired. 
     U.S. Patent Publication No. 2009/0160604 (the &#39;604 publication) of Nguyen that published on Jun. 25, 2009 describes a vehicle speed control system that automatically affects vehicle operation based on a vehicle location relative to a designated speed control zone. Specifically, the &#39;604 publication describes a system that includes a computer for controlling operating functions of a vehicle when RFID tags onboard the vehicle are sensed by an offboard station positioned adjacent the designated speed control zone. The offboard station is capable of sending a speed control command to the vehicle as the vehicle passes through the speed control zone, thereby causing components of the vehicle to automatically reduce the speed of the vehicle. The components reduce the speed of the vehicle by reducing vehicle fueling. 
     Although the system of the &#39;604 publication may automatically reduce vehicle speed in a designated control zone, the speed reduction may have an insignificant effect on air consumption or quality within the zone. In addition, by controlling only vehicle fueling, inefficiencies may be realized. Further, the system of the &#39;604 publication may only function in zones equipped with the offboard station, which can be limiting and expensive. 
     The disclosed control system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art. 
     SUMMARY 
     In one aspect, the present disclosure is directed to a control system for a machine. The control system may include an engine configured to combust a mixture of fuel and air and generate a mechanical power output and a flow of exhaust, and a sensor configured to generate a signal indicative of the machine moving between zones having different air characteristics. The control system may also include a controller in communication with the engine and the sensor. The controller may be configured to selectively adjust operation of the engine based on the signal in an amount related to the air characteristics. 
     In another aspect, the present disclosure is directed to another control system for a machine. This control system may include an engine configured to combust a mixture of fuel and air and generate a mechanical power output and a flow of exhaust, and a sensor configured to generate a signal indicative of the machine moving between zones having different air characteristics. The control system may also include a controller in communication with the engine and the sensor. The controller may be configured to determine a number of other machines currently in at least one of the zones, and to selectively adjust operation of the engine based on the signal and based on the number of other machines currently in at least one of the zones. 
     In yet another aspect, the present disclosure is directed to a method of controlling a machine. The method may include making a first determination that the machine has moved between zones having different air characteristics, and making a second determination of a number of other machines currently in at least one of the zones. The method may further include selectively derating the machine based on the first and second determinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a pictorial illustration of an exemplary disclosed machine control system. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a worksite  10  and an exemplary machine  12  performing a task at worksite  10 . Worksite  10  may include, for example, a mine site, a landfill, a quarry, a construction site, or another type of worksite having a roadway  14  traversable by machine  12 . In some applications, roadway  14  may be bordered on at least one side by a wall  16 , for example a wall of an underground tunnel. Although shown in  FIG. 1  as a single lane roadway, it is contemplated that roadway  14  may alternatively include multiple lanes, if desired. 
     The task being performed by machine  12  may be associated with altering the geography at worksite  10  and include, for example, a hauling operation, a grading operation, a leveling operation, or a bulk material removal operation. As such, machine  12  may embody a mobile machine, for example a haul truck, a motor grader, or a loader. Machine  12  may include, among other things, a body  18 , one or more traction devices  20  that support body  18  and propel machine  12 , and a control system  22  that produces and controls a power output used to drive traction devices  20 . 
     Control system  22  may include a collection of components that cooperate to produce the power output directed to traction devices  20 . Specifically, control system  22  may include a power source  24 , a transmission  26 , and a controller  28  in communication with power source  24  and transmission  26 . Controller  28  may be configured to selectively regulate operation of power source  24  and transmission  26  in response to various input to drive traction devices  20  and propel machine  12  in a desired manner. 
     Power source  24  may include an internal combustion engine having multiple subsystems that cooperate to produce the power output discussed above. Although power source  24  is depicted and described as a four-stroke diesel engine, one skilled in the art will recognize that power source  24  may be any other type of internal combustion engine such as, for example, a gasoline or a gaseous fuel-powered engine. The subsystems included within power source  24  may include, for example, a fuel system, an air induction system, an exhaust system, a lubrication system, a cooling system, and/or any other appropriate system. Any or all of these subsystems may be controlled by controller  28  to adjust an amount of or manner in which air and/or fuel is directed into and combusted within power source  24  and thereby the mechanical power output produced by power source  24 . 
     Power source  24  may be configured to operate at one or more rated conditions. For the purposes of this disclosure, the rated conditions may be considered the conditions under which power source  24  produces advertised power (e.g., operates at optimum performance along an advertised lug curve). Power source  24  may be derated by reducing an amount of fuel and/or air combusted within power source  24  and/or by adjusting a manner in which the fuel and air is combusted (e.g., by adjusting a timing of power source  24 ). When derated, power source  24  may produce power at a level less than advertised. 
     A speed sensor  30  may be associated with power source  24  to sense an output speed thereof. In one example, speed sensor  30  may embody a magnetic pickup type of sensor associated with a magnet embedded within a rotational component of power source  24  such as a crankshaft or a flywheel. During operation of power source  24 , speed sensor  30  may sense the rotating field produced by the magnet and generate a signal corresponding to the rotational speed of power source  24 . 
     Transmission  26  may embody a hydrostatic transmission, an electric transmission, a mechanical transmission, or any other type of transmission known in the art. Transmission  26  may be configured to receive a rotational input from power source  24  and produce a rotational output having a different speed and torque directed to traction devices  20 . Transmission  26  may be selectively shifted by controller  28  to adjust the ratio between the input and output speeds and torques. It is contemplated that transmission  26  may be capable of any number of different ratios in a forward and a reverse travel direction. The structure of transmission gears, input members, output members, coupling members, and the connections therebetween can be achieved using components known in the art. 
     Controller  28  may embody a single or multiple microprocessors, field programmable gate arrays (FPGAs), digital signal processors (DSPs), etc., that include a means for controlling operations of power source  24  and transmission  26  in response to signals received from speed sensor  30  and from one or more environmental sensors  32  mounted, for example, on an external surface of machine  12 . Numerous commercially available microprocessors can be configured to perform the functions of controller  28 . It should be appreciated that controller  28  could readily embody a microprocessor separate from that controlling other machine-related functions, or that controller  28  could be integral with an machine microprocessor and be capable of controlling numerous machine functions and modes of operation. If separate from the general machine microprocessor, controller  28  may communicate with the general machine microprocessor via datalinks or other methods. Various other known circuits may be associated with controller  28 , including power supply circuitry, signal-conditioning circuitry, actuator driver circuitry (i.e., circuitry powering solenoids, motors, or piezo actuators), and communication circuitry. 
     Environmental sensor  32  may be attached, for example, to a side of machine  12  and configured to generate a signal indicative of movement of machine  12  between zones  36  having different environmental air characteristics. In one embodiment, environmental sensor  32  may embody a radio frequency identification (RFID) receiver configured to detect radio waves generated by one or more RFID tags  34  and generate a corresponding signal. In the disclosed embodiment, pairs of RFID tags  34 , including a first RFID tag  34   a  and a second RFID tag  34   b , may be placed at boundaries between zones  36  having substantially different air characteristics. It should be noted that zones  36  may have zone-wide average air characteristics that are substantially different from each other, even though air characteristics at the boundaries of zones  36  may, in some situations, be nearly identical. In the disclosed example, first and second RFID tags  34   a, b  are placed at spaced apart locations alongside roadway  14 , for example in wall  16 , in a tunnel ceiling, in roadway  14  itself, or in another location. In this manner, as machine  12  traverses roadway  14 , environmental sensor  32  may detect RFID tags  34   a, b  and alert controller  28  when machine  12  crosses the corresponding boundary between zones  36 . It is contemplated that information about a particular zone  36  (e.g., the air characteristics of that zone  36  or air use limitations associated with the characteristics) may also be transmitted from RFID tags  34   a, b  to environmental sensor  32  as machine  12  passes by, if desired. It is also contemplated that any number of RFID tags  34  may be utilized to demarcate each zone  36 . 
     It is contemplated that, instead of RFID tags  34  only demarcating a boundary of zone  36 , RFID tags  34  may alternatively be placed at consistent intervals within zone  36 . As long as environmental sensor  32  regularly detects RFID tags  34 , machine  12  may be considered to be operating within zone  36  or outside of zone  36 , as desired. When sensor  32  fails to detect an RFID tag  34 , machine  12  may be considered to have left or entered zone  36 . In some embodiments, a time or distance buffer may be utilized to account for a missing or faulty RFID tag  34 , if desired. Additionally or alternatively, RFID tags  34  may be regularly placed along an entire length of roadway  14 , with some RFID tags  34  providing different information regarding the location of or air characteristics of zone  36 . 
     The air characteristics of each zone  36  may be include at least one of a known air quality and a known air supply rate. In particular, as described above, some locations within long mining tunnels may be poorly ventilated. As a result, the quality of air at these locations may make the locations unsuitable for prolonged human occupation. Additionally or alternatively, the supply rate of air to these locations may be less than machine  12  or a group of co-located machines  12  together is capable of consuming at rated conditions. For this reason, these locations may be periodically tested for the air characteristics and separated into zones  36  identified by RFID tags  34  according to specific levels of air quality and supply rate and/or according to corresponding use limitations. RFID tags  34  may then be used to alert machine  12  of zone boundaries or locations and, in some embodiments, also inform machine  12  of the corresponding air characteristics and/or use limitations. 
     It is contemplated that environmental sensor  32  may embody a sensor other than an RFID receiver, if desired. For example, environmental sensor  32  could be associated with a locating device such as a GPS receiver, an odometer, an optical scanner, a camera, etc. that provides machine positional information to controller  28 . Based on this information and a stored map of zones  36 , controller  28  may then be configured to determine when machine  12  crosses boundaries between zones  36  and thereby the corresponding associated are characteristics and/or use limitations. In yet another example, environmental sensor  32  could be configured to directly detect the quality and/or quantity of available air at locations along roadway  14 , if desired, and according to one or more preprogrammed algorithms determine when machine  12  crosses between zones  36  (i.e., when machine  12  moves between locations having significantly different air characteristics) and the corresponding use limitations. 
     Controller  28  may be configured to adjust performance of machine  12  based on signals from environmental sensor  32 . Specifically, controller  28  may be configured to derate machine  12  when machine  12  is determined to be operating within a zone  36  having less desirable air characteristic. For example, when controller  28  detects the presence of first RFID tag  34   a  and machine  12  crosses the corresponding boundary into a zone  36  having a low quality or supply rate of air and associated use limitations, controller  28  may communicate with the subsystems of power source  24  to reduce an amount of torque in the mechanical output provided to transmission  26  (i.e., to reduce a power output of power source  24 ). In one example, controller  28  may communicate with the fuel system of power source  24  to reduce fueling and thereby reduce the output of power source  24 . It is contemplated, however, that controller  28  may also or alternatively communicate with other subsystems of power source  24 , for example the air induction system, if desired, to accomplish the torque reduction of power source  24 . When controller  28  detects the presence of second RFID tag  34   b  and machine  12  crosses the boundary out of the zone  36  having the less desirable air characteristic, controller  28  may stop or reduce the torque reduction of power source  24  (i.e., controller  28  may return operation to rated conditions). Controller  28  may derate machine  12  by a desired amount such that emissions from machine  12  do not further reduce the air quality in zone  36  below an acceptable level and/or such that an air consumption rate of machine  12  does not exceed an acceptable threshold amount of the air supply rate within zone  36 . 
     The amount of torque reduction affected by controller  28  when machine  12  is operating in zone  36  may be variable and based on several different factors. In one example, controller  28  may reference the air characteristic of a particular zone  36  with a lookup map stored in memory and determine a desired torque reduction for the particular host machine  12 . Controller  28  may then reference the signal from speed sensor  30  with the same or another lookup map and determine a reduction in fueling corresponding with the current engine speed of power source  24  and the desired torque reduction. Controller  28  may also be configured to determine a number and/or type of other machines  12  currently operating within zone  36 , and determine the desired torque reduction and corresponding fueling reduction such that the combined operation of all machines  12  in zone  36  complies with restrictions associated with the air characteristics. 
     Controller  28  may also be configured to control transmission  26  based on signals from environmental sensor  32 . Specifically, controller  28  may include stored in memory two or more different shift maps relating engine speed and transmission shift points. When it is determined that machine  12  is operating within a zone  36  having a less desirable air characteristic, controller  28  may utilize a first of the shift maps to control the gear ratio of transmission  26  and, when it is determined that machine  12  is operating outside of that particular zone  36 , controller  28  may use a second of the shift maps. The two shift maps may include different engine speed settings for use as shift points between gear ratios. In one example, the first shift map may have shift points that occur at relatively lower engine speeds compared to the second shift map. By controlling transmission  26  differently based on zones  36 , travel speeds of machine  12  may be maintained more consistently with operator expectations and transmission shifting may be relatively smooth even with reduced engine output. 
     Controller  28  may further be configured to generate an alert of operation within a zone  36  having a less desirable air characteristic. Specifically, controller  28  may be configured to illuminate a warning lamp  38  or activate another similar device informing an operator of machine  12  that RFID tag  34   a  has been detected and/or that machine derating has begun. Similarly, controller  28  may stop illuminating warning lamp  38  when RFID tag  34   b  has been detected and/or when machine derating has been stopped. It is contemplated that an operator, when alerted by controller  28 , may have the opportunity to override or otherwise adjust the machine derating, if desired. 
     INDUSTRIAL APPLICABILITY 
     The disclosed control system may be applicable to any mobile machine where a quality and/or supply rate of air in an environment of the machine is a concern. The disclosed control system may be particularly applicable to underground mining applications, where the machine operates in long tunnels with compromised ventilation. Operation of control system  22  will now be described. 
     During travel of machine  12  along roadway  14 , machine  12  may pass by RFID tags  34  placed, for example, in walls  16  of an underground tunnel. As described above, RFID tags  34  may demarcate the boundaries between and/or locations of zones  36  having different air characteristics. For example, a first zone  36  may have a lower air quality and/or a lower supply rate of air than an adjoining second zone  36 . If unaccounted for, normal machine operation within first zone  36  could degrade the quality of air below an acceptable level, consume all or too much of the available air, or result in malfunction because of insufficient air. 
     Accordingly, as machine  12  passes first RFID tag  34   a , environmental sensor  32  may detect the presence of first RFID tag  34   a  and generate a corresponding signal directed to controller  28 . In some embodiments, first RFID tag  34   a  may provide information regarding the air characteristic of first zone  36 , for example the current air quality, the current air supply rate, an emission limit, an air consumption limit, and/or a desired machine operating level. Controller  28 , upon receiving the signal from environmental sensor  32 , may make a determination that machine  12  has entered first zone  36  and derate machine  12  by a corresponding amount. That is, controller  28  may reduce a fueling of power source  24 , reduce a charge air supply of power source  24 , and/or adjust a timing (e.g., fuel injection or valve timing) of power source  24 , and affect transmission shifting between gear ratios according to the air characteristics of first zone  36  and a number and/or type of other co-located machines  12  such that operation of machine  12  remains within desired limits. Controller  28  may also illuminate warning lamp  38  at this time. 
     As machine  12  passes second RFID tag  34   b , environmental sensor  32  may detect the presence thereof and generate a corresponding signal directed to controller  28 . In some embodiments, second RFID tags  34   b , in addition to signaling an end boundary of zone  36 , may also provide an indication as to the air characteristic of the adjoining zone  36 . That is, it is contemplated that different areas having varying levels of low air quality and/or supply may exist near each other. In this situation, RFID tags  34  may be placed between these areas providing information as to the different air quality and supply levels and/or to the desired machine operation within the different areas. Controller  28 , upon receiving the signal from environmental sensor  32 , may make a determination that machine  12  is leaving first zone  36  and either return machine operation to rated conditions or adjust machine operation (i.e., increase or decrease the derating of machine  12  by a desired amount) according to the air characteristic in the new area that machine  12  is entering. If entering a new area of sufficient air quality and supply, controller  38  may stop illuminating warning lamp  38  at this time. 
     Several benefits may be associated with the disclosed control system. For example, because controller  28  may affect machine operation based on the air characteristic of a particular zone  36 , an air quality and/or machine operation within zone  36  may be maintained at a desired level. Further, by controlling transmission operation also based on the air characteristic and on derated power source operation, machine performance, efficiency, and productivity may remain high. Further, by locating environmental sensor  32  onboard machine  12  and RFID tags  34  offboard, any number of relatively inexpensive RFID tags  34  may be located along roadway  14  without significant additional cost, thereby allowing machine operation to be adjusted as many times as necessary during a single trip of machine  10  along roadway  14 . 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the control system of the present disclosure. Other embodiments of the method and system will be apparent to those skilled in the art from consideration of the specification and practice of the control system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.