of allowing the engine to automatically stop and restart, second condition of automatically stopping the engine after the function is set and third condition of automati- cally restarting the engine after the function is set are fulfilled ornot,respectively,ismadeby"and"ofaplurality of signals including at least two or more signals out of a signal indicating an engine rotational speed, a signal in- dicating the generating condition of an alternator and a third signalindicating readiness or unreadiness for start- ing of the vehicle. 

[0010] There is a need for improvement in engine idle shutdown apparatus and thermalmanagementmethods which integrate with the vehicle’sexisting systems,mon- itor various vehicle parameters, and safely and rapidly shut down the engine when prescribed idle conditions exist. These idle shutdown mechanisms need to accom- plish the prescribed shutdowns without risk of damage to the engine or associated components, and within a consistent time frame, even when being affected under widely varying vehicle and ambient conditions. 

[0011] The need for improvement may be illustrated by way of the example of a typical conventional vehicle idle shutdown routine. The idle shutdown procedure be- gins at t=0, at which point a shutdown timer is activated to time a controlled idle period. After the timer expires, the engine is shutdown. In this example, the vehicle en- gine coolanttemperature is209°degreesFahrenheit(ap- proximately 98 °C) when the initial idle shutdown condi- tions are metand the shutdown system isturned on.The vehicle engine cooling fan is off. Because the initial tem- perature is above 200° degrees Fahrenheit (approxi- mately93 °C),however,idle shutdown timingissuspend- ed (made inactive) until the engine coolant temperature decreases below athreshold temperature (topreventen- gine damage). In this example, the ambient air temper- ature is above 80° degrees Fahrenheit (approximately 27 °C),which resultsinslowheattransferfromthe engine to the environment,with the temperature decreasing only two degrees Fahrenheit (approximately 1.1 °C) over the first 330 seconds. At this time the engine cooling fan ac- tivates, resulting in the vehicle engine coolant tempera- ture decreasing six degrees Fahrenheit (approximately 3.3 °C) in the next 80 seconds. At t=550 seconds, the idle shutdown timer 1 switches from inactive to active status, turning offthe engine automatically aftera period of 300 seconds has elapsed. Engine load has changed during thisprocess,remaining atapproximately ten percent. 

[0012] This situation is undesirable since the operator activated the idle shutdown device at t=0, but because the enginecoolanttemperature was above 200°degrees (approximately 93 °C)att=0,the idle shutdown timerwas on hold,or inactive, until the engine coolant temperature decreased to 200° degrees Fahrenheit (approximately 93 °C), at t=550. The idle shutdown timer then switched to active, and shuts the engine down 300 seconds (five minutes) later. Thus, the operator believed that the en- gine would shutdown 540 seconds (nine minutes)sooner 

than it did, which could result in violation of laws or reg- ulations, wastes fuel, and adds wear and tear to the en- gine and its components. As a result, the operator loses faith in the typical idle shutdown device. 

[0013] In at least one embodiment, the presently dis- closed solution ofthe invention according toclaim1takes the form of a method for controlling an automatic shut- down process that promotes cooling down an internal combustion engine of a vehicle to a predetermined safe shutdown temperature when vehicle-idle conditions are detected. The method includes initially determining that vehicle-idle conditions exist. At a minimum, these condi- tions include making a determination that the engine of the vehicle isrunning atidlespeed.An engine-associated temperature is then measured and it is determined whether the measured temperature is above a first tem- perature value, said first value being defined according to the risk of engine damage if shutdown at that temper- ature, as explained in greater detail hereinbelow. In this regard,theengine-associated temperature may relateto any numberofengine systems orcomponents,however, for the purposes of clarity of description, the present dis- closure primarily focuses on engine coolant tempera- tures. 

[0014] Responsive to determining that the measured temperature is above the first threshold, a cooling fan directly driven by the engine is operated. The engine- associated temperature ismonitored and coolingfan op- eration is reduced when the engine-associated temper- ature is determined to have decreased below the first threshold temperature value. Typically, the reduction in fan operation will be to zero speed, or stopped, but it is contemplated that the fan may be merely slowed below the operationalspeed previouslyaffected.Ultimately,en- gine shutdown is completed when predetermined shut- down conditions are determined to exist, and which may include thevehicle notmoving(i.e.,stationary),the trans- missioninneutraloroutofgear,the engine atidlespeed, and the engine-associated temperature being below the first threshold temperature value. 

[0015] The invention furthercomprises additionalcool- ing action if the engine-associated temperature is above a second threshold value higher than the first threshold temperature. Responsive to this condition, the fan is op- erated and engine speed is increased above idle speed to increase fan speed to more rapidly cool the engine. When the engine-associated temperature decreases to below the second threshold temperature, engine speed is returned to the idle speed, and the fan continues to operate while the temperature isabovethe firstthreshold temperature. A programmed control system is utilized to control the occurrence, level, and time period during which increased engine speed is affectedwhile the cool- ing fan is engaged, the control managing these param- eters so todecrease the engine-associated temperature. 

[0016] The invention contemplates that a time delay period can be initiated after the engine-associated tem- perature is determinedto have decreased below the first 

