Patent Application
20070050193
1. Technical Field
The invention relates to commercial vehicle management and more particularly to using motor vehicle control electronics to document fuel usage categories and to generate detailed fuel usage reports for State and provincial highway use tax reporting.
2. Description of the Problem
A commercial vehicle's engine provides power for moving the vehicle along public roads but may also be used to support applications unrelated to operation of the vehicle on such roads. The fuel burned to support vehicle operation on a road is subject to fuel taxes. However, for exempt vehicles, fuel used for other purposes may be excluded from taxation and credit may be claimed from governmental authorities upon presentation of acceptable proof of non-taxable use. In addition, knowledge of the apportionment of taxes to particular jurisdictions based on actual fuel used within a jurisdiction may be advantageous to an operator.
A vehicle engine may provide a power source for the generation of electrical, hydraulic and pneumatic power in addition to providing power for moving the vehicle. This electrical, hydraulic and pneumatic power may in turn be variously applied. For example, hydraulic power is often employed for power take-off operations (PTO) such as wrecker winches. Fuel used to operate a winch is arguably not taxable. The vehicle may be driven off public roads in which case none of the fuel burned is taxable. In some cases it may be arguable that fuel burned during extended periods of idling is not taxable. Often non-taxable fuel usage is readily identifiable. One case would be where a vehicle has an auxiliary engine used for a specialized, non-motive function such as running a refrigerator pump. Here fuel flow to the auxiliary engine is readily tracked and excluded from tax. However, determining the proportion of fuel consumed by a primary power plant when it is used to support a function which is auxiliary to operation of the vehicle is typically more complex.
As vehicles move across State and provincial boundaries the authority to whom tax is owed changes. The determination of which jurisdiction a vehicle is in is readily supported by use of geographic positioning systems (GPS) to find the vehicle's location. Electronics based, fuel tax reporting systems adapted to determining jurisdiction for allocating fuel taxes are known.
A number of factors complicate the measurement of fuel used for taxable and non-taxable purposes. Controllers for diesel engines typically measure fuel mass flow. However, taxation of fuel is based on the volume of fuel used, not the mass used. The formula for converting mass to volume does not have fixed value parameters. For example, summer and winter blends of fuel are formulated to vary volatility of the fuel, with lighter distillates being used more in the winter, and heavier, middle distillates being used more in the summer. Engine fuel flow measurement, which is designed to determine mass of the fuel used, will produce differing results, when equated to volumetric equivalents, for equal masses depending upon the blend of the fuel used.
Worse, fuel flow measurement errors tend to be cumulative. On the other hand, fuel level sensors used in tanks can be made highly accurate, but even the best such devices have a margin of error of a sixteenth of an inch. While over a long period of operation measurement errors should cancel out, measurements taken over short periods are subject to a high degree of uncertainty. PTO operation of the vehicle may come in 10 to 20 minute bursts. The fuel level change in the fuel tank over so short a period may be less than the margin of error of the sensor, introducing a high degree of uncertainty in the volume of fuel used. A fuel flow device, allowing for the possibility of error already described, is a more reliable instrument over short periods than a fuel level sensor but can exhibit systematic, cumulative error for repeated operations.
What is desirable is the refinement, integration and extension of such systems to provide detailed fuel usage reports, both for improving vehicle and fleet management, and for assuring that accurate amounts are paid for taxes.
According to the invention there is provided a vehicle management system for categorizing fuel usage, particularly for categorizing fuel usage for purposes of taxation and documenting claims for tax exempt use. The vehicle management system comprises a first data link installed on the motor vehicle. An engine sensor group monitors engine operating variables and returns values for those variables, including fuel flow, to an engine controller. The engine controller is coupled to the engine sensor group for receiving the reported engine operating variables and is responsive to these for generating fuel rate usage messages. The engine controller is connected to the first data link and puts the fuel rate usage messages and selected engine operating values on the first data link. A body controller, which has access to the first data link, reads the fuel rate usage messages. The body computer compares vehicle location information with public right-of-way location information to categorize usage as non-taxable if the vehicle is off public right-of-ways. The body computer includes further programming responsive to the engine operating variable values reported on the first data link, and other inputs, for determining whether the engine is idling and, if so, for how long it has idled. The body computer is programmed to be further responsive to determination that the engine has idled for a first minimum period for categorizing further use of fuel as non-taxable for as long as the engine continues to idle. The body computer may also be programmed to respond to data link messages indicating power take-off operation and other accessories have been engaged for allocating a portion of fuel usage as non-taxable.
Additional effects, features and advantages will be apparent in the written description that follows.
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
Referring now to the figures and in particular to
Commercial vehicle 102 includes an electronic control system based on a controller area network (CAN) system 104. Controller area network system 104 links numerous controllers onboard commercial vehicle 102 for data communication and allows central activation and control of remote data communications services through cellular phone link 108. Controller area network 104 has a node which incorporates a global positioning system unit 106 for determining a vehicle's location from the constellation of GPS satellites 110.
Cell phone base station 112 is linked by land lines including, if advantageous, the internet, to transfer data from cell phone link 108 to a vehicle operator's server 114. The data from the vehicle 102 can include, as set forth in detail below, information relating to engine loading, fuel flow and other vehicle operating variables collected by the CAN system 104 as well as information specifying the vehicle's location. Records forwarded from vehicle 102 can be readily time, date, location and mileage stamped if required to document factors supporting a demand for the refund of payment of fuel taxes.
In a preferred embodiment of the invention, server 114 maintains databases 128 of fuel usage indicating amounts used (or in increments of predetermined volume), the character of the use and the location of use (e.g. on or off a public highway, or in which jurisdiction). Alternatively, these records may be maintained on onboard computers installed on the vehicles. The location of use determinations may be made by reference to a database package including a geographic information system (GIS) database. GIS databases are available which specify the location of public roads. Alternatively, a GIS database may be accessed over a network link. Whether a GIS database is maintained on the vehicle, on a central server, or is accessed by the central server may depend upon the licensing terms available for the particular GIS databases consulted. A data processing system 124 associated with server 114 can provide for database update and interrogation. Similar facilities may be provided on vehicle 102. In addition, the databases 128 may indicate minimum power requirements for the operation of vehicle accessories.
Referring now to
Among the other parts of the microcomputer 230 are input/output devices for handling on board communications between controllers including first and second controller area network (CAN) interfaces 250 and a SAE J1939 or J1708 interface 270 (shown connected to switch bank 271). Microprocessor 272 may also directly control features of electrical subsystems 233. Here the electrical subsystems 233 may include one or more sources of precision fuel property measurements such as taken from an ultrasonic fuel tank level sensor 273, a fuel flow and viscosity sensor 475, or a fuel temperature sensor 275. In addition, a vehicle mounted tilt/road grade sensor 375 may be provided for adjusting or preventing use of measurements from a fuel tank level sensor 273. Where an ultrasonic fuel tank level sensor 273 is employed, programming of the body computer 230 will provide for time averaging of the data to filter out variation in level due to slosh of fuel in a fuel tank (not shown). Fuel level sensors can also be conventional types or capacitive types. An engine external fuel flow and viscosity sensor 475 communicating with body computer 230 may also be used.
The engine controllers 220 used with diesel engines 263 typically provide a measurement of fuel flow based upon engine speed, injection pressures, fuel charge shaping generated by the engine controller based upon operating conditions and assumed fuel temperature under stabilized conditions. The engine sensor package 221 may include a highly accurate turbine flow meter. Accurate knowledge of system oil pressure can be used to determine more precisely and accurately the probable range of fuel volume injected by an injector and better knowledge of viscosity (as a function of fuel temperature) allows more precise determination of restriction. Generally, fuel flow is best measured under “stable conditions”. Values for engine operating variables indicating stable oil and fuel temperature are good indicators of such “stability”. The fuel rate signal is directly proportional to fuel mass flow though the parameters of the functional relationship may vary. There are accuracy problems with measuring fuel flow in this way. Precision instruments such as ultrasonic fuel tank level sensor 273 and a fuel temperature sensor 275 can provide greater accuracy in measurement of fuel flow up to the limit of economic justification. However even the best of these systems suffer from a lack of precision which makes short duration fuel usage measurement problematical. However, by allowing calibration of fuel mass flow sensors provided with engine sensor package 221 using accurate, long term fuel use measurement from level sensors, improved accuracy of flow rate can be obtained. Using the fuel temperature and viscosity measurements combined with indicated flow from a turbine flow meter can give highly accurate fuel flow measurements when calibrated.
Given a long enough operating period, the fuel rate signal may be calibrated and proportioned to fuel volume usage. Such calibration is done using a fuel level sensor 273 and takes place over an operational period long enough to produce a change in fuel level much larger than the margin of error of the fuel level sensor. As noted above, errors in fuel flow produced by engine controllers tend to accumulate. Those produced by a fuel level sensor 273, on the other hand, tend to cancel overtime. Thus, well calibrated fuel flow calculations will provide highly accurate short term measurements of fuel usage. Calibration is done under stable engine operating conditions, indicated by stable engine oil and fuel temperature readings.
The economic justification for highly accurate fuel usage determination stems largely from the potential tax savings available. Tax savings will depend in turn on the number of auxiliary tasks imposed on a vehicle prime mover, from the presence of auxiliary engines which draw fuel from the same fuel tank as the vehicle engine 263, or from frequent use of the vehicle off public roads. Consider a situation where measurements of fuel flow can be assured to be within 5% accuracy. It is probable that the amounts of fuel excluded from road use taxation will have the lowest level which is known with high assurance to have been used for non-taxed activities. Thus the greater the assured accuracy, the greater the tax savings. However, accuracy has its own price in terms of expense in equipment. For example, fuel flow turbines are frequently inaccurate at extremely low flow rates (the turbine can simply stop turning). The more expensive the turbine generally the broader its range of accurate operation. Fuel rate can be combined with other engine operating variables to determine power output and load. Multiple sources of fuel flow information (e.g. changes in fuel level averaged over time versus direct measurement) can be used for calibration. Alternatively, these systems can be calibrated by measurement against known quantities before putting the vehicle into the field. What is preferred though is to use highly accurate, but temporally low resolution, fuel level sensors periodically to calibrate fuel flow measurement under stable operating conditions. For example, once stable operating conditions are established, and under circumstances where an operator expects an extended period of uninterrupted operation, a calibration operation begins. Fuel level is sensed, and for an extended period fuel flow is sampled. At the end of the period fuel level is again sensed. Fuel usage is the integral of a fuel flow, and particular flow rates can be adjusted to reflect their proportion contributed to fuel used as measured by the level sensors. Repeated calibration is required to compensate for changes with use in the equipment and seasonal and geographic variation in fuel blends. Where fuel flow is not directly reported, engine load may be estimated as a precursor to estimating fuel flow. Systematic errors in measurement of engine load are minimized by improved accuracy in fuel flow estimation or measurement by adjusting for fuel temperature, hydraulic injector pressure and using engine external flow sensors.
Microprocessor 272 is readily programmed to monitor the proportion of the total load on engine 263 contributed by different vehicle subsystems, so long as the equipment is OEM equipment. Examples of such equipment can be PTO hydraulic pumps or climate control system 280 pumps and fans. The loads imposed on engine 263 may be stored in memory 272 in lookup tables or expressed as a function. Air conditioning compressor pumps are typically on or off, and when on, impose a fixed, and known, load on the engine. Operational status of the devices such as an A.C. pump are readily reported on a J1939 bus. The load represented by such a device is readily stored as an entry in a look up table where the input argument is simply identification of the device. In more advanced, electrically powered cab climate systems 280 or refrigeration systems, the cooling pump may run constantly but vary in output based on exogenous variables, such as the difference between a desired cab temperature and outside air temperature. This sort of varying load may be stored as a series of values in a look up table dedicated to the device and using temperature difference as an input argument.
Fuel flow to engine 263 is either allocated to particular purposes based on the loads imposed on the engine, or it is directly measured if to an auxiliary engine or other direct user of fuel other than the primary engine 263. CAN system 104 includes two distinct controller area networks based on a first bus using the public codes of the Society of Automotive Engineers (SAE) standard for J1939 networks and a second bus on which manufacturer defined codes are used. The public bus connects first CAN interface 250 to a plurality of system controllers including an instrument and switch bank 212, a gauge cluster 214, an anti-lock brake system controller 219, a transmission controller 216 and an engine controller 220. Any of these controllers may in turn be connected to one or more sensors, or to sensor packages, associated with a specific controller. For example, ABS controller 219 collects data from sensors 231 which include at least the wheel speed sensors used for determining skidding. Transmission controller 216 may track transmission fluid levels or include a drive shaft tachometer from drive train sensors 217. By far the most important collection of sensors though is the engine sensor package 221 connected to the engine controller 230 which includes an engine tachometer and an air intake temperature gauge (providing a reasonable surrogate for ambient temperature). These and other readings may be used for sophisticated assessments of engine loading and when combined with throttle position indication are used to calculate fuel flow. Fuel mass flow is then provided by engine controller 220 to a fuel injection system and back to body computer 230 which equates it volume usage.
A second CAN network provides for connections to a group of controllers not critical to direct vehicle operation, but which control auxiliary loads on engine 263 or control equipment which independently taps the vehicle's fuel reservoir, or provide information used to implement an embodiment of the invention. Shown attached to body computer 230 over CAN interface 250 are a GPS receiver unit 242, an auxiliary power unit controller 244, a cell-phone transceiver unit 240 and a power takeoff operation (PTO) controller 245. Each of these controllers include a CAN interface 250 allowing exchange of data with the microprocessor 230 as well, in theory, with each other. Transceiver unit 240 includes a microcontroller 241, a modulating unit 243 and a transceiver unit 245 connected to an antenna 247 and provides for communications with a remote server such as described in connection with
A vehicle may be equipped with an auxiliary engine or auxiliary power unit 293 which may consume fuel from the same reservoir as engine 263. Fuel flow to an auxiliary power unit 293 is easily monitored by an APU sensor package 297 and an APU controller 244, which reports fuel usage by APU 293 on the second CAN bus for receipt by body computer 230. Vehicles such as wreckers come with PTO 295 capability, typically powered by a hydraulic pump run off the vehicle's power or drive train 290. Loading the drive train 290 PTO in turn loads the engine. In the case of a wrecker, it may be called upon to generate considerable power output to load a large, disabled automobile at a location on a public highway. All fuel flow reported by an engine sensor package 221 under these circumstances should qualify as non-taxable.
The flow chart of
At this point categorization, or proportional allocation, of the latest increment to fuel used as taxable or non-taxable may be done. In this example, this begins by fetching (step 305) location from the GPS unit 242. At step 307 location is compared with data from a geographic information system database. If the vehicle's current location is on a public thoroughfare, the process continues to more particularly categorize fuel usage (the YES branch). If vehicle 102 is not on a public thoroughfare all fuel consumed may immediately be categorized as non taxable (step 309 along the NO branch from step 307) and program execution may be returned for the next sample. The GIS may be locally stored or remotely accessed through server 114.
Following the YES branch from step 307 fuel usage is categorized by its character rather than by its location to determine taxability. Where to begin such categorization is largely arbitrary, and a number of possible algorithms may be employed. Here it has been chosen to determine first if the engine 263 is idling as may be indicated by the park brake being set with the engine running. Alternatively, engine sensors 311, such as the engine tachometer are read. Vehicle speed is then obtained from a drive train tachometer 217, as indicated at step 313. Both tachometer readings are placed on the CAN 1 bus by engine controller 220. Where the vehicle is not moving, has not moved for a minimum period and the engine output is low, as determined at step 315, it may be taken that the vehicle is idling and that fuel consumed may be excluded from taxation. Total fuel expended idling is shown as allocated to non-taxable use at step 317 following the YES branch from decision step 315. The total may be tracked as a monitor of driver performance, particularly where company policy or environmental law restrict idling periods.
If the vehicle is not idling, the NO branch is followed from step 315 to step 319 to fetch PTO status. In most PTO applications the vehicle is typically stopped, and it is assumed, for purposes of example, that such is the case here. Following determination that PTO is engaged at step 321 the YES branch is taken to step 323 and all fuel usage is categorized as non-taxable.
A vehicle may operate on a public road while the engine 263 supports another load which contributes to fuel consumption. For example, the vehicle may be hauling product that is required to be kept refrigerated. Fuel expended to support such a load may not be taxable. Fuel may be expended to regenerate a catalytic converter or particulate trap. Fuel used in this way may also not be taxable. Any number of examples can be thought of. In addition, commercial vehicles may operate in more than one state, province, or other tax jurisdictions. Steps 325, 327 relate to auxiliary vehicle functions unrelated to generation of motive power. At step 325 the vehicle's auxiliary systems are “interrogated” by monitoring the appropriate messages available to body computer 230 over the CAN 1 and CAN 2 networks. Database data may be used to attribute fuel usage to functions indicated as engaged if measurement or estimation of fuel usage attributable to the function is not available. An example of a system for which fuel usage can be directly measured is considered next with processing shown as advancing to steps 329 where measurement of fuel usage by an APU is attributed to the non-taxable category. Step 331 relates to handling of the allocation of fuel used by both auxiliary systems and the APU 293. Finally, all non-taxable uses are subtracted from total incremental use at step 333. At step 335 the current jurisdiction is determined from the GPS data and the balance found at step 333 is allocated to that jurisdiction's taxable total.
While the invention is shown in only a few of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.
