Internal-combustion engines – Starting device – Condition responsive control of starting device
Reexamination Certificate
1999-10-07
2001-01-09
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Starting device
Condition responsive control of starting device
C123S1960CP
Reexamination Certificate
active
06170452
ABSTRACT:
This invention relates generally to the field of the operation of internal combustion engines, and more particularly to a method and apparatus for restarting an engine prior to it cooling beyond a predetermined temperature.
BACKGROUND OF THE INVENTION
It is well known that it can be difficult to start an internal combustion engine from a cold condition, particularly during cold weather conditions. When an engine is out of service, the engine lubricating oil will achieve a temperature consistent with the ambient air temperature, and it will become highly viscous. Upon starting the engine from the cold condition, the lubricating oil will gradually warm to its normal operating temperature. However, during the warm-up period, the operation of the lubricating system is degraded due to the high viscosity of the oil. Cold starting of an internal combustion engine is made more difficult due to the increased friction caused by the high oil viscosity, and engine parts may experience accelerated wear rates during the warm-up period due to the degraded lubricating system performance.
Self-propelled vehicles commonly utilize an internal combustion engine as a prime mover. The assignee of the present invention is a supplier of locomotives powered by turbo-charged diesel engines, such as the General Electric model GE7FDL16 diesel engine. Such engines are subject to the disadvantages discussed above during cold starting conditions. Furthermore, the operating instructions for a locomotive may include limitations on the engine throttle settings prior to the engine achieving full operating temperature. In cold weather conditions, there may be a delay of more than one hour after starting the locomotive engine from cold conditions until the engine is capable of operating at full throttle. U.S. Pat. No. 4,592,323 issued to Vest on Jun. 3, 1986, and assigned to the assignee of the present invention, discloses a system for limiting the maximum speed of the diesel engine of a locomotive when the lubricating oil is relatively cool and hence highly viscous. The Vest patent describes the design and operation of a diesel locomotive engine system in some detail and is incorporated by reference herein. For some applications, such as when operating in a switch yard, a locomotive is used for only short periods followed by periods of inactivity. In order to avoid delays in the availability of such engines, particularly in cold weather conditions, it is common for the engine of the locomotive to be placed in the idle position during periods of inactivity. Although this approach is effective in maintaining the engine at operating temperature, it also results In the wasting of fuel during the idling periods. Alternatively, the engine may be shut down between periods of operation in order to conserve fuel, however, this increases the risk the temperature of the lubricating oil will drop below the desired operating level.
FIG. 1
illustrates the lubricating oil system of a prior art diesel locomotive engine
10
. An oil pump
12
draws oil from the engine
10
and delivers it to an oil cooler
14
. The oil cooler
14
functions to transfer heat from the engine oil to a cooling water supply (not shown). The oil is then pumped through a filter
16
and returned to engine
10
. For many applications, such as the GE7FDL16 diesel engine, the temperature of the oil is measured at a point in the lubricating oil system that is remote from the engine
10
. As illustrated in
FIG. 1
, it is common for the temperature of the oil to be measured by a temperature sensor
18
located downstream of pump
12
near the inlet of cooler
14
. Such a location is convenient for the design of the lubricating oil system, and it provides an accurate measurement of the lubricating oil temperature during the operation of the engine. However, during periods of engine shutdown, the oil becomes stagnate within the lubricating oil system and/or drains completely out of the filter
16
and cooler
14
and returns to the engine
10
. Therefore, during engine shutdown conditions, temperature measuring device
18
is ineffective for providing an indication of the lubricating oil temperature within engine
10
. Therefore, the operator of the locomotive will have no reliable indication of the actual lubricating oil temperature within engine
10
and will be unable to predict whether the operation of the engine
10
will be delayed upon startup due to lubricating oil temperature limitations. As a result, in order to assure that the locomotive will always be available for full power service, it is common practice to allow the engine to operate at idle conditions during periods of inactivity.
BRIEF SUMMARY OF THE INVENTION
Thus, there is a particular need for a method and apparatus for operating an engine in a manner that prevents cold starts and that improves the fuel efficiency of the engine. A method of operating a locomotive engine is provided comprising the steps of: obtaining an average cool down rate of the engine oil after shutdown of the engine; shutting down the engine; obtaining the oil temperature at the time of engine shutdown; calculating a maximum shutdown time for the engine by subtracting a predetermined minimum oil temperature from the oil temperature at the time of engine shutdown and dividing that difference by the average cool down rate; and restarting the engine before exceeding the maximum shutdown time. In addition, an apparatus for operating a locomotive engine is provided comprising: a means for storing an average engine cool down rate; a means for measuring the ambient temperature at the time of engine shutdown; a means for measuring the oil temperature at the time of engine shutdown; a controller connected to the means for storing, means for measuring the ambient temperature, and means for measuring the oil temperature, the controller comprising a means for calculating a maximum shutdown time as a function of the average oil cool down rate, the ambient temperature at the time of engine shutdown, and oil temperature at the time of engine shutdown; a means for measuring time elapsed after engine shutdown connected to the controller; and a means for starting the engine connected to the controller and operable to start the engine when the time elapsed after engine shutdown equals or exceeds the maximum shutdown time.
REFERENCES:
patent: 4413595 (1983-11-01), Potts, Jr.
patent: 4592323 (1986-06-01), Vest
patent: 4847768 (1989-07-01), Schwartz et al.
patent: 5072703 (1991-12-01), Sutton
patent: 5159313 (1992-10-01), Kawai et al.
patent: 5317998 (1994-06-01), Hanson et al.
Dolinar Andrew M.
General Electric Company
Holland & Knight LLP
Huynh Hai
Maire David G.
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