Abstract:
A method for timing performance of a maintenance function, in particular the timing of regeneration of a diesel particulate filter ( 22 ) to conserve fuel as a motor vehicle ( 10 ) travels along a projected travel route. Certain road data about roads in a roadway system is processed to develop data for anticipating certain modes of vehicle operation during travel of the vehicle along the projected travel route. The data for anticipating certain modes of vehicle operation along the anticipated route of travel and data geographically tracking vehicle travel along the projected route are interactively used to control timing of performance of the maintenance function as the vehicle travels along the projected route.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    This disclosure relates generally to systems and strategies for controlling tailpipe emissions from motor vehicles, such as trucks, that are powered by internal combustion engines, especially diesel engines whose exhaust systems have certain exhaust gas treatment devices, such as diesel particulate filters (DPF&#39;s), that from time to time are regenerated. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    A known after-treatment system for exhaust gas passing through an exhaust system of a diesel engine comprises a diesel oxidation catalyst (DOC) associated with a diesel particulate filter (DPF). The combination of these two exhaust gas treatment devices promotes chemical reactions in exhaust gas and traps diesel particulate matter (DPM) as exhaust flows through the exhaust system, thereby preventing significant amounts of pollutants such as hydrocarbons, carbon monoxide, soot, SOF (soluble organic fraction), and ash, from entering the atmosphere. 
         [0003]    A DPF is regenerated from time to time in order to maintain particulate trapping efficiency. Regeneration involves creating conditions that will burn off trapped particulates whose unchecked accumulation would otherwise impair DPF effectiveness and/or engine performance. 
         [0004]    At times a vehicle may be operating in a way that inherently burns off trapped materials in a DPF. This naturally occurring regeneration is sometimes called “passive” regeneration. Passive regeneration generally has little or no significant effect on either fuel economy or vehicle driveability. 
         [0005]    When trapped materials accumulate in a DPF faster than they are passively removed, they eventually reach a level, often expressed as a percentage, that calls for the DPF to be regenerated. A regeneration initiation and control strategy in the engine controller forces regeneration. Such a forced regeneration is sometimes referred to as “active” regeneration. 
         [0006]    A typical regeneration initiation and control strategy controls air and fuel management systems in a manner that elevates engine exhaust gas temperature to one that is high enough to burn off trapped DPM. One way to elevate exhaust gas temperature is by post-injection of fuel. 
         [0007]    Active regeneration is less efficient than passive regeneration because extra fuel is used to elevate the exhaust gas temperature. Apart from causing some reduction in vehicle fuel economy, active regeneration may also have an effect on vehicle drivability that if significant enough, should be addressed to assure customer satisfaction. 
       SUMMARY OF THE DISCLOSURE 
       [0008]    The present disclosure describes a regeneration initiation and control system and strategy for a DPF that interactively processes certain data, including telemetric data that enables the geographical location of the vehicle to be determined and data about certain characteristics of either a planned, or projected, travel route along roads of a roadway system for timing the initiation of active regeneration to coincide with vehicle travel along a segment of the route that would be expected to result in the use of less extra fuel for regeneration than would be expected to be used when the vehicle is traveling along a different segment of the route. 
         [0009]    The disclosed system and strategy can postpone the time at which active regeneration would otherwise commence, or advance the time at which active regeneration would otherwise commence, or do neither. 
         [0010]    If, upon issuance of a regeneration request occurring when soot accumulation in the DPF has increased to some given percentage, a more distant ensuing segment of a travel route contains roads along which regeneration of the DPF would be expected to use less extra fuel than along a less distant ensuing segment because of diversity between certain physical characteristics of the respective road segments and/or because of certain restrictions on how vehicles can lawfully operate on the respective road segments, then regeneration can be postponed. The intent of such a postponement is to allow the vehicle to reach and begin traveling along the more distant segment with the expectation that a net savings in the extra fuel that would be used for regeneration can be realized, or the possibility that passive regeneration might occur and delay active regeneration even more. However, the consequence of any delay that could potentially impact compliance with applicable tailpipe emission requirements or potentially damage equipment in the vehicle should be considered before permitting the delay, and if the soot accumulation in the DPF increases by some amount beyond the aforementioned percentage, then regeneration is initiated. 
         [0011]    If, upon issuance of a regeneration request occurring when soot accumulation in the DPF has increased to some given percentage, a more distant ensuing segment of a travel route contains roads along which regeneration of the DPF is expected to use more extra fuel than along a less distant ensuing segment because of diversity between certain physical characteristics of the respective segments and/or because of certain restrictions on how vehicles can lawfully operate on the respective segments, then regeneration can be allowed to commence without delay, the intent still being the expectation of realizing a net savings in the extra fuel that would be used for active regeneration. 
         [0012]    If the level of trapped DPM in the DPF is insufficient to request active regeneration while the vehicle is traveling along a segment of a travel route before intending to stop, but if the distance to the stopping point and road conditions along the way are expected to initiate active regeneration before the vehicle arrives at the stopping point and the resulting regeneration may not be complete by the time the vehicle arrives there, then the disclosed system and strategy can initiate active regeneration early enough to expect complete regeneration by the time the vehicle does stop. 
         [0013]    One general aspect of this disclosure relates to a vehicle comprising an engine for propelling the vehicle comprising an exhaust system through which exhaust gases created by combustion in engine cylinders pass to atmosphere and which comprises an after-treatment device that treats the exhaust gases before leaving the exhaust system but that at times is regenerated by elevation of temperature of the exhaust gases to a regeneration temperature range, a telematic system providing geographical data tracking travel of the vehicle along roads in a roadway system, a database containing an electronic map of the roadway system that includes road data about roads in the roadway system useful in anticipating certain modes of engine operation during travel of the vehicle along roads in the roadway system, and an engine controller for initiating, controlling, and terminating regeneration of the after-treatment device. 
         [0014]    The after-treatment device comprises an operating strategy that interactively uses both road data from the database to anticipate modes of engine operation along an anticipated route of travel of the vehicle over roads in the roadway system and geographic tracking data from the telematic system to time initiation of regeneration of the after-treatment device. 
         [0015]    Another general aspect relates to a strategy for timing regeneration of an after-treatment device in an exhaust system of an engine in a motor vehicle for propelling the vehicle along a projected route of travel over roads in a roadway system. 
         [0016]    The strategy comprises geographically tracking the location of the vehicle as it travels along roads in the roadway system, processing certain road data about roads along the projected route of travel useful in anticipating certain engine operating data along the projected route to develop certain anticipated engine operating data along the projected route, and using the anticipated engine operating data to time initiation of regeneration of the after-treatment device as the vehicle travels along the projected route. 
         [0017]    The disclosure in perhaps more general aspects relates both to a motor vehicle comprising a telematic system providing geographical data tracking travel of the vehicle along roads in a roadway system, and a controller for controlling timing of performance of a maintenance function for a device in the vehicle and comprising an operating strategy for interactively using certain road data about roads in the roadway system to anticipate certain modes of vehicle operation during travel of the vehicle along a projected route of travel along the roadway system and geographical tracking data tracking vehicle travel along the projected route to time performance of the maintenance function as the vehicle travels along the projected route, and also to a method for timing performance of such a maintenance function. 
         [0018]    The method comprises processing certain road data about roads in the roadway system to develop data for anticipating certain modes of vehicle operation during travel of the vehicle along the projected travel route, and interactively using the data for anticipating certain modes of vehicle operation along the anticipated route of travel and data geographically tracking vehicle travel along the projected route to control timing of performance of the maintenance function as the vehicle travels along the projected route. 
         [0019]    The foregoing summary, accompanied by further detail of the disclosure, will be presented in the Detailed Description below with reference to the following drawings that are part of this disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  shows portions of a truck relevant to the present disclosure. 
           [0021]      FIG. 2  is a geographical map useful in explaining some aspects of the disclosure. 
           [0022]      FIGS. 3  is a strategy diagram useful in explaining the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]      FIG. 1  shows a truck  10  that is propelled by a diesel engine  12  that is coupled by a drivetrain  14  to driven wheels  16 . The example shown represents a highway tractor for hauling a trailer, or tandem trailers, coupled to the tractor&#39;s fifth wheel. 
         [0024]    Truck  10  has an electronic data system that includes various electronic modules for processing various data to control various systems and devices. One such module is an engine controller  18  that has one or more processors processing data from various sources to develop various data that is used for informational and/or control purposes. The data that is processed may originate at external sources and/or be generated internally. 
         [0025]    Engine  12  also has an exhaust system  20  through which exhaust gases created by combustion of combustible mixtures in combustion chambers of engine  12  are exhausted to the surrounding atmosphere. Exhaust system  20  comprises one or more after-treatment devices, one of which is a diesel particulate filter (DPF)  22  that traps diesel particulate matter (DPM) so that such matter does not pass through to tail pipe  24  and into the surrounding atmosphere. 
         [0026]    The combustion chambers of engine  12  comprise cylinders into which fuel is injected by fuel injectors of a fueling system  26  to combust with charge air that has entered through an intake system. Energy released by combustion powers the engine via pistons connected to a crankshaft leading to drivetrain  14  for propelling the vehicle. 
         [0027]    The fuel injectors are under the control of controller  18 , typically through injector drivers, to force fuel out of the injector tips into the combustion chambers. Intake valves control the admission of charge air into the cylinders, and exhaust valves control the outflow of combustion gases through exhaust system  20  and ultimately to atmosphere. 
         [0028]    As explained earlier, DPF  22  is regenerated from time to time in order to burn off trapped DPM. When a regeneration request issues because of disclosure that the percentage of trapped soot has reached a level at which regeneration would be appropriate, engine controller  18  can initiate and control regeneration, such as by changing fueling and/or air management, to suitably condition the exhaust gases so that they can become effective to burn off the trapped DPM. 
         [0029]    The percentage of trapped soot in DPF  22  can be determined in any suitably appropriate way, such as by measuring the pressure/flow characteristic of the DPF. Actual initiation of regeneration may also be conditioned on certain other conditions being favorable. 
         [0030]    Truck  10  is equipped with a telematic system  28  embodying wireless technology and GPS tracking technology for enabling data to be exchanged between the truck and a location remote from the truck and for enabling the truck&#39;s geographical location to be determined using the Global Positioning System. 
         [0031]    Telematic system  28  communicates wirelessly through an antenna system  30  with one or more satellites of the Global Positioning System and bi-directionally with a nearby tower of a cellular communications system. The cellular communications system has bi-directional communication with a land-based station remote from the truck. Module  28  can also communicate with other devices and modules in the truck&#39;s electronic data system via a data bus or busses in the truck. 
         [0032]    As truck  10  travels along roads of a roadway system, its ability to receive and process data from the Global Positioning System provides the truck&#39;s data system with geographical data tracking its location. That data can also be transmitted to the land-based station. 
         [0033]    The execution of the disclosed strategy is performed by engine controller  18  with the interactive use of telemetric system  28 . An electronic map of a roadway system on which vehicles can travel and certain data about roads in the roadway system are contained in telematic system  28 . The map and road data can be permanently stored in system  28  or alternately loaded into the system via wireless communication from a remote station having a database containing the data. The data about roads in the roadway system provides information useful in anticipating how engine  12  would be expected to operate as it propels truck  10  along roads in the roadway system. 
         [0034]    An example of a map  40  is portrayed visually in  FIG. 2 . Map  40  contains various roads along which vehicles can travel. One is a multi-lane expressway  42  having entrance and exit ramps to and from a highway  44  having a bridge that crosses over the expressway. Other roads  46 ,  48  intersect road  44 . 
         [0035]    The data about the roads may comprise, for example, legal speed limit data, traffic control device data, road intersection data, and/or road grade data. 
         [0036]    A projected route of travel for truck  10  can be established either at the land-based station or on-board the truck. The projected route can be mapped either by a person using certain available information about a roadway system or by a route-planning algorithm having access to a database having a map of the roads and certain information about them. 
         [0037]    Once a route has been projected, data about roads along the route is processed by an algorithm that analyzes the data to anticipate how a vehicle may be operated as it travels along various sections of the route. The analysis yields anticipated vehicle operating data, including engine speed and load data anticipated to occur along those various sections. That data can then be used to distinguish sections of the route along which the truck would use less extra fuel for active regeneration of the DPF from sections along which the truck would use more extra fuel for active regeneration. For example a section that is free of traffic control devices and intersections and/or has a high legal speed limit (expressway  42  for example) can be distinguished from a section that has frequent traffic control devices, frequent intersections, and a low legal speed limit. Data about the presence or absence of significant uphill and/or downhill grades is also useful. The work used in climbing a significant uphill grade will elevate exhaust temperature, promoting regeneration, while descending a downhill grade reduces engine load, and consequently exhaust temperature as well. 
         [0038]    As truck  10  travels along the projected route, the GPS tracking that enables the truck&#39;s location along the route to be determined and anticipated engine speed/load data resulting the analysis of the route explained above are processed to allow a regeneration request to initiate an active regeneration, or to postpone an active regeneration that has been requested, or to initiate an active regeneration earlier that it would otherwise likely occur. 
         [0039]    Data that discloses trapped DPM present in DPF  22  is available on a data bus or busses in truck  10 , as is data that represents the truck&#39;s geographical location determined by telematic system  28 . Data for trapped DPM, data for truck location, and data about expected engine speeds/loads along different sections of the travel route are processed by engine controller  18 . An example of a flow diagram  60  of the processing is disclosed in  FIG. 3 . 
         [0040]    Trapped DPM data, i.e. % DPF soot accumulation  62 , is evaluated by a step  64  for the purpose of determining whether or not the accumulated soot exceeds some amount, x %, above which an active regeneration request will issue. If x % is not exceeded, then regeneration is not initiated (reference numeral  66 ). If x % is exceeded, then a step  68  is performed. 
         [0041]    Step  68  evaluates current engine speed/load data to ascertain whether or not the data lies in a zone of a speed/load plot within which the regeneration request should be allowed to initiate active regeneration, provided that other applicable conditions, if any, are also satisfied. 
         [0042]    If the data is disclosed not to lie in such a zone, then a step  70  is performed for the purpose of determining whether or not the accumulated soot exceeds some amount y % which exceeds x % by some amount. If y % is exceeded, then active regeneration is initiated as shown by a step  72 . A value for x % represents a particular amount of accumulated soot at which it is considered worthwhile to perform regeneration, as distinguished from the greater value for y % that has been determined to represent an amount of accumulated soot at which regeneration will be forced. 
         [0043]    If step  68  instead discloses that the current engine speed/load data does lie in such a zone, then active regeneration is initiated (step  69 ), subject to other conditions, if any, that also have to be satisfied. 
         [0044]    If step  70  determines that the accumulated soot doesn&#39;t exceed y %, the engine load/speed data projected to occur during vehicle travel along an ensuing segment of the route as a result of the analysis described earlier and the current location of the truck along the projected route, as determined by telemetric system  28 , are processed (step  72 ) to determine if future travel along a more distant segment would or would not use more extra fuel for active regeneration than would be used during future travel along a less distant segment of the route. 
         [0045]    If the processing discloses that less extra fuel would be used, then active regeneration is postponed (step  66 ) with the expectation that a net savings in the extra fuel that would be used can be realized by the postponement, or that passive regeneration might occur once travel along the more distant segment commences further delaying active regeneration. If the processing discloses that more extra fuel would be used, then a step  74  is performed. 
         [0046]    Step  74  determines whether or not truck  10  is expected to stop at some point along the projected route before reaching the ensuing more distant segment of the route. 
         [0047]    If it is not, then regeneration is delayed (step  66 ) in the expectation of affording the truck the opportunity to begin travel along the ensuing more distant segment of the route that may be more favorable for conserving extra fuel used for regeneration. 
         [0048]    If the truck is expected to stop, then active regeneration is initiated (step  69 ). 
         [0049]    In this way, if a period of low engine speed/load driving is expected, controller  18  will either preemptively regenerate DPF  22  or else delay regeneration depending on whether or not a stop is anticipated. A reason for performing regeneration before a stop is because it would be expected that the engine and exhaust would have warmed to typical operating temperatures as the truck was being driven along the prior portion of the route, whereas if regeneration is initiated after the truck has stopped and the engine and exhaust system have cooled, extra fuel is used to perform regeneration during the time that the engine and exhaust have not yet reached typical operating temperatures. 
         [0050]    While processing has been described as occurring in truck  10 , some processing could be performed remotely. For example, the database of road information could be at a remote site. The geographical location of the truck and its projected route could be wirelessly transmitted to the remote site for processing in conjunction with data from the database to develop data for projected engine speeds/loads during future travel of the truck along the projected route. That data could then be wirelessly transmitted to the truck for processing in conjunction with the on-board regeneration initiation and control strategy to make an appropriate determination as to whether timing of active regeneration should be postponed or allowed to proceed in response to a regeneration request or whether regeneration should neither be advanced nor postponed.