Data processing: measuring – calibrating – or testing – Measurement system – Performance or efficiency evaluation
Reexamination Certificate
2000-10-24
2003-05-13
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Performance or efficiency evaluation
C702S145000, C702S189000, C702S176000, C700S281000, C700S282000, C701S029000, C701S030000, C701S069000, C701S100000, C123S204000, C123S206000
Reexamination Certificate
active
06564172
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to locomotive fuel usage, and more specifically, to a method and apparatus for evaluating locomotive fuel efficiency and usage as determined by the locomotive operator's handling of the train during a given train run.
Large self-propelled traction vehicles, such as locomotives, commonly use a diesel engine to drive an electrical transmission system comprising a generator for supplying electric current to a plurality of direct current traction motors, whose rotors are driving coupled, through speed-reducing gearing, to the respective axle-wheel sets of the vehicle. The generator typically comprises a 3-phase traction alternator whose rotor is mechanically coupled to the output shaft of the engine, typically a 16-cylinder turbo-charged diesel engine. When excitation current is supplied to field windings of the rotating rotor, alternating voltages are generated in the 3-phase stator windings. The output voltage is rectified and applied to the armature windings of the traction motors. The diesel engine may also be driving coupled to an auxiliary alternator for supplying alternating current at a constant frequency to the various auxiliary systems on the locomotive or on the cars pulled by the locomotive.
During the “motoring” or propulsion mode of operation, a locomotive diesel engine delivers constant power from the traction alternator to the traction motors, depending on the throttle setting and ambient conditions, regardless of the locomotive speed. For maximum performance, the electrical power output of the traction alternator must be suitably controlled so that the locomotive utilizes full engine power. For proper train handling, intermediate power output levels are provided to permit graduation from minimum to full output. But the traction alternator load on the engine must not exceed the level of power the engine is designed to develop for a given speed. Overloads can cause premature wear, engine stalling or “bogging,” or other undesirable effects. Historically, locomotive control systems have been designed so that the operator can select the desired level of traction power, in discrete steps between zero and maximum, so that the traction and auxiliary alternator, driven by the engine, can supply the power demanded by the traction load and the auxiliary loads, respectively.
In the prior art locomotives, when the throttle is advanced from one position to the next (commonly referred to as notches) the diesel engine speed and/or the load (or excitation) applied to the traction motors are simultaneously increased to the speed and horsepower point established for the new notch position. Some notch position changes may involve only a speed change, others only a horsepower change and still others a change in both the engine speed and delivered horsepower. The engine acceleration to the new speed point is controlled by the electronic fuel injection controller that adjusts the quantity of pressurized diesel fuel (i.e., fuel oil) injected into each of the engine cylinders so that the actual speed (in rpm) of the crankshaft corresponds to the desired speed. If the new notch position also commands a new horsepower value, the locomotive control system applies more excitation to the main alternator, which in turn supplies more current to the traction motors, increasing the motor horsepower.
The engine electronic fuel injection controller controls the engine speed in response to speed changes requested by the locomotive control system by way of a notch position change made by the locomotive operator. Generally, the fuel injection controller does not receive any signals from the throttle when it is changed from one notch position to another and therefore does not know when a notch change has occurred. Instead, the speed governor knows only the speed demand as requested by the locomotive control system. In fact, there may be multiple notch settings that vary the horsepower delivered by the traction motors without changing the engine speed.
For each of its eight different notch settings, the engine is capable of developing a corresponding constant amount of horsepower (assuming maximum output torque). When the throttle notch 8 is selected, maximum speed (e.g., 1,050 rpm) and maximum rated gross horsepower (e.g., 4,500) are realized. The engine power at each notch equals the power demanded by the electric propulsion system, which is supplied by the engine-driven traction alternator, plus the power consumed by the electrically driven auxiliary equipment.
The locomotive fuel system includes a tank, a low pressure subsystem, and a high pressure subsystem. A typical diesel locomotive tank has a capacity of 5,000 gallons. A low pressure pump provides approximately seven gallons per minute (at 40 pounds per square inch (psi)) from the tank to a fuel header which supplies fuel to the high pressure pumps. Each cylinder has its own high pressure pump. In turn, the high pressure pump injects the fuel into a fuel injector at each diesel engine cylinder at a pressure of between 18,000 and 20,000 psi. At idle, approximately only 10% of the fuel drawn for the fuel tank by the low pressure pump is used for combustion. At notch 8, the percentage rises to approximately 60% to 70%. A pressure regulator interposed between the low pressure pump and high pressure pump bleeds off the unburned excess fuel not used for engine combustion and returns it to the fuel tank via a drain line. Also, the high pressure delivered by the high pressure pumps, causes some fuel to leak from the fuel injectors. This unused fuel is collected from the injectors and also drained back to the fuel tank. Typically, a 16-cylinder diesel engine has one fuel injector drain for each 8-cylinder block.
An electronic fuel injection controller provides a pulse input to high pressure pump solenoids that drive high pressure pumps and thereby control the injection of fuel into each cylinder. The leading edge of the pulse sets the start of fuel injection, and the pulse length determines the duration of fuel injection into the cylinder. The pulse duration determines the fuel mass that is injected into each cylinder, as measured in mm
3
/injection. Look-up tables provide the required start of injection timing as a function of engine speed and fuel value, which is a measure of the volume of fuel being injected into each cylinder.
The efficient functioning of diesel locomotive engines, especially as it relates to fuel usage, is an important factor in the operational costs of the railroad. Periodically, diesel locomotive engines are tested for output to determine whether a repair or overhaul is necessary. Various testing methods are used, with one common test employing a dynamo meter for measuring the mechanical output power of the engine. Another method utilized in the prior art simply considers the total miles run or diesel engine operational horsepower-hours. It is recognized, however, that these methods do not allow for precise analysis of the engine condition due to variations between engines, especially engine combustion conditions.
The most efficient method of determining engine condition is to measure the actual amount of fuel consumed by the engine per unit of work. In accord with the dual pump system discussed above, the measurement of fuel consumption requires four flow meters, with one flow meter on each of the three return lines and a fourth flow meter on the supply line. The four flow meter readings must be summed to calculate the amount of fuel used by the diesel engine. This is not accomplished without difficulty, due to inherent inaccuracies in the system and measuring devices and further the expense associated with installing such a system. But, given the high fuel costs, generally the highest cost element associated with operation of a railroad, it is especially important to ensure the locomotives are in excellent operating condition and further that the locomotive operators employ efficient operational techniques to contain the fuel costs.
In addition to budget matters,
Beusse Brownlee Bowdoin & Wolter P.A.
DeAngelis Jr. John L.
Desta Elias
Hoff Marc S.
Rowold Carl A.
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