Idle Air Control Systems: Fill & Download for Free

You all have observed many times that diesel locomotives are kept idle in the yards and also when waiting for too long in the yards or station especially for goods train. Loco pilots can switch off the diesel engine and save fuel instead of running in IDLE conditionBut they don't do becauseThe brake pipe pressure reduces due to the leakages and it takes longer time to build up working pressure again. It is very curcial when waiting for the signal on the grade.A proper checklist have to followed to recrank the engine . It takes 10-15 min to do so when starting after a long shutdown.To keep the compressor running , engine must not be switched off as it is coupled with the engine.As the diesel engine contains usually 16 cylinders and are also big in size , so it is quite difficult to achieve ignition temperature.There are many auxiliary components running so if one fails or some technical parameter changes may cause problem in starting.During idling a lot of fuel get wasted only to charge the batteries and to kept the air compressor running. By using APU, main engine shuts down and small 25hp engine starts, and charges batteries and air brake pipes, when the train is idle for more than 10 minutes. The diesel engine of APU consumes only three litres of diesel per hour in comparison to 25 litres by the main engine. Expected savings per locomotives fitted with APU is Rs 20 lakh per year on account of saving in fuel oil.APU is a self-contained unit containing a small diesel engine coupled to a compressor and alternator for battery charging. It has its own set of controls, accessories and is integrated to the existing microprocessor control system of locomotive.APU is located in the nose compartment under dynamic brake grid resistors and after the air brake panel.This is an Add on unit to Microprocessor based loco control system.It is called as AESS with APU.It starts automatically and stops automatically as per the drivers request.The Tier 4 locomotive is designed for a typical lifespan of 25 to 30 years.Please up-vote and share if you like.

Not knowing your year, model and engine I can only tell you some general items that pertain to most cars.There electrical relays and switch's ,about 2 dozen on average. When you shut the car down the radiator fans can be active until the engine temp cools to specs. Evaporative emissions systems do some of their work at shutdown. Fuel systems depressurize in many engine in order to prevent wear that constant pressure can induce. Many of today's cars have automatic parking brakes and many cars have done away with cables and use electronics to change gears and engage park. Some ABS brake system cycle at shutdown and idle air control can be active at shutdown. I can go on and on but I think this should help you to understand that electrical relays and fluid pressure systems all can make clicking noises after shutdown.I assume that the louder more random ticks with a metallic sound you know are metal parts cooling down after shutdown.Most of the relay sounds are done with in 2 mins and the metal cool down noises are done with in 5–10 mins depending on temp.As a bonus I will bring to your attention a fairly new item not quite under the hood but behind the grill and that is electrically operated “grill flappers” or “blinds per se” that help your car control temp and help aerodynamic performance at higher speeds. My wife's car opens them up after shutdown if they were closed at that point.Hope this helps!

Idle air control is the method some fuel injected vehicles utilize to maintain a proper idle speed during a wide variety of conditions. It also has the secondary function of controlling emissions upon sudden throttle closure. The basics of the system involves using a solenoid ,valve, or stepper motor to regulate the amount of air bypassing the throttle plate at closed throttle. This “idle air bypass valve” or “idle air controll valve” is operated by the Powertrain Control Module. It is used for the simple reason that it is not possible to set the throttle plate at one permanent location and maintain proper idle speed under all conditions. Many later model vehicles have done away with idle air control systems. These vehicles utilize a throttle plate directly controlled by the PCM at all times. There is no direct link from the accelerator pedal to the engine's throttle plate. The driver inputs from the accelerator pedal position sensor are used by the PCM to open or close the throttle. In such a system the PCM, through use of a throttle actuator, will make slight adjustments to throttle opening to maintain a proper idle speed under all conditions. This throttle control system has also allowed for the elimination of extra servos and cables that were previously required for cruise control operation.