Measuring and testing – Test stand – For engine
Reexamination Certificate
1998-11-09
2001-11-20
Dombroske, George (Department: 2855)
Measuring and testing
Test stand
For engine
Reexamination Certificate
active
06318160
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to locomotives, and more specifically, to an apparatus and method for testing locomotive engines and associated systems.
During routine shop maintenance, generally every ninety-two days, the diesel engine of a locomotive is tested. For example, the diesel engine is typically operated at various predetermined horsepower levels while onboard temperature sensors and engine control parameters are recorded. The recorded data is then archived for future reference.
FIG. 1
diagrammatically illustrates a power plant system
10
of a locomotive. A diesel engine
30
is tested by operating throttle
20
, which throttle
20
is operably connected to diesel engine
30
, at each throttle position or notch. Each throttle position sets and fixes a different engine speed (i.e., rpm). A dynamic braking grid
50
(resistive heating elements used for braking the locomotive) imposes a load on an alternator
40
, which alternator
40
is operably connected to diesel engine
30
, to achieve a maximum horsepower for the set throttle position. During the test, electrical power normally provided to electric traction motors
60
for driving the wheels of the locomotive is diverted to dynamic braking grid
50
. Each throttle position is maintained for a period of 15 to 20 minutes.
Attempts to analyze the recorded data are often unsuccessful because the water cooling radiator fans
80
of radiators
70
cycle between discrete speeds (off, ¼ speed, ½ speed, full speed) while maintaining the cooling water at an operating temperature of, for example, 155 degrees F. In addition, changing of the radiator fan speed is accomplished by having radiator fans
80
brought up to full speed and then adjusted downwardly to the desired lower speed. Fluctuation in the water cooling temperature due to the cycling of radiator fans
80
ranges from 5 degrees F. to 10 degrees F. depending on the throttle position and the ambient air temperature. The transient nature of the cooling system precludes accurate diagnostics of diesel engine
30
and associated systems, for example, thermal diagnostics that are on the same order of magnitude as the fluctuation in temperature of the water for determining whether the cooling system is operating a few degrees too hot or too cold. For diesel engine
30
operating at, for example, 900 rpms and 3,300 hp,
FIG. 2
illustrates a graph of the cyclic nature of the cooling water temperature over time.
The cycling of radiator fans
80
on and off also varies the load on diesel engine
30
so that the horsepower generated by the engine (as determined by measuring the current and voltage produced by the alternator) varies over time as illustrated in FIG.
2
. In particular, radiator fans
80
have a diameter of three to four feet and draw 100 hp during operation.
While such a test may indicate whether engine
30
is operating generally at an expected horsepower level at a specific throttle position, such a test cannot be used to readily identify trends in the performance of the engine, the thermal systems, the electrical power systems, etc. For example, on a hot day, although the horsepower level of the engine may be reached, the radiator fans may be operating at ¾ speed when they should be operating on ½ speed, or the fuel system may be providing excess fuel to the engine in order to reach the desired horsepower level.
Therefore, there is a need for an apparatus and method for testing a power plant system of a locomotive in which engine and associated systems are maintained in a thermally steady state.
SUMMARY OF THE INVENTION
The above-mentioned need is met by the present invention which relates to diagnostic techniques for testing a power plant system of a locomotive. One aspect of the present invention comprises a method for testing a power plant system of a locomotive in which the method includes the steps of maintaining the power plant system at a thermally steady state, and obtaining at least one measurement of the power plant system.
The step of maintaining the engine at a substantially constant operating temperature may include the step of operating a throttle operably connected to an engine at a predetermined throttle position, operating a radiator fan of a radiator operably connected to the engine at a predetermined radiator fan speed, and operating an alternator operably connected to the engine to apply a substantially constant load to the engine. Desirably, the predetermined radiator fan speed of the radiator fan is based on ambient temperature.
In another aspect of the present invention, an apparatus for testing a power plant system of a locomotive includes a controller adapted to maintain the power plant system at a thermally steady state, and the controller being adapted to obtain at least one measurement of the power plant system.
In still another aspect of the present invention, an article of manufacture comprises at least one computer usable medium having computer readable program code means embodied therein for causing the testing of a power plant system of a locomotive. The computer readable program code means in the article of manufacture includes computer readable program code means for maintaining the power plant system at a thermally steady state, and computer readable program means for obtaining at least one measurement of the power plant system.
In yet another aspect of the invention, at least one program storage device readable by a machine, tangibly embodying at least one program of instructions executable by the machine performs a method of testing a power plant system of a locomotive. The method includes maintaining the power plant system at a thermally steady state, and obtaining at least one measurement of the power plant system.
REFERENCES:
patent: 4223654 (1980-09-01), Wessel et al.
patent: 4425878 (1984-01-01), Samuel
patent: 4549504 (1985-10-01), Gaines et al.
patent: 5564390 (1996-10-01), Houtz et al.
patent: 5806011 (1998-09-01), Azzaro et al.
patent: 6006731 (1999-12-01), Uzkan
patent: 6058904 (2000-05-01), Kruse
Dombroske George
General Electric Company
Patnode Patrick K.
Stoner Douglas E.
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