Why should diesel engines not run at low speed for a long time?

The diesel engine runs at low speed for a long time, which has the following disadvantages:

Affect the quality of diesel atomization. The quality of diesel atomization is mainly related to the injection pressure, the diameter of the injection hole and the speed of the camshaft. For a certain diesel engine, the diameter of the fuel injection hole is fixed, so the quality of diesel atomization depends on the injection pressure and camshaft speed, the higher the injection pressure and the faster the camshaft speed, the better the diesel atomization, and the speed of the camshaft changes with the speed of the crankshaft, when the speed of the diesel engine crankshaft is lower than the rated speed, the diesel atomization will become bad, and the longer time will cause the engine to run abnormally, so it is not suitable to run at low speed for a long time.

By: Netizen.

The interval between low-rev operations of diesel generators varies mainly by the type of generator and the environment in which they are used. Under normal circumstances, the interval between low-rev operation of diesel engines should not be less than 200 hours. If it is a special environment, such as a construction generator or a special purpose generator, the interval between low-rev operations will be shorter, and may not be less than 150 hours.

In addition, when meeting the requirements of the low-speed operation interval of the power generation jujube land cultivation machine, it is also necessary to carry out maintenance work such as maintenance according to the operation condition of the generator and the stool to ensure the normal operation of the generator.

Dear, we are glad to answer for you that diesel generators can not run at low speed for a long time, and it is generally recommended that the rated load should not be less than 50%. For example, if the dust fruit runs at low speed for a long time, the engine will not be able to completely burn the fuel, which will cause the oil to dilute, increase carbon deposition, and aggravate the wear of the piston ring, which will seriously affect the life and performance of the motor. Therefore, care should be taken to maintain a proper load when using diesel generators and avoid long-term low-rev operation. 

1. This is the embodiment of the instability of the diesel engine, mainly due to the following reasons:

2. When idling, the cylinder leaks a large amount of air, and the cylinder spike or energy loss is more, which makes the compression temperature and pressure low, the fuel atomization is not good, and the combustion fluctuation is large; The oil supply is small at idling, and the slight change in the oil supply of each cylinder will lead to the difference in the working state of each cylinder. The uneven oil supply of each cylinder during this idle speed will lead to the idle travel phenomenon of the diesel engine; The direct injection of diesel engine makes the injection pressure develop to high pressure, especially the use of porous fuel injector, so that the nozzle is not high in accuracy when providing a small amount of oil, and it is easy to fluctuate, and the unstable fuel supply of diesel engine is an important reason for the instability of idle speed; The increase in the service time of the fuel injection system and the aging of the fuel injection system make the fuel injector nozzles, oil outlet valves and other components of each attitude lift cylinder different, resulting in further uneven oil volume and aggravating the fluctuation of idle speed.

3. There is only one solution, go to a professional repair point for repair.

The following is a list of common fault causes: 1. Fuel pipeline: The air inlet of the fuel pipeline leads to poor and unstable oil supply.

2. Oil supply: the unevenness of oil supply of each cylinder exceeds the standard. Under the idle condition, the unevenness of the oil supply of each cylinder shall not exceed the specified range (generally 12).

Otherwise, the diesel engine may fuel the vehicle when it is running at idle. If necessary, the unevenness of oil supply should be adjusted on the oil pump test bench. 3. Fuel injection pressure difference:

The difference in fuel injection pressure between each cylinder is too large, and the atomization quality is uneven, which also makes the speed of the diesel engine unstable. At this time, the injection pressure should be adjusted to improve the atomization quality and ensure that the pressure deviation of each cylinder is within the allowable range. 4. Governor:

The governor flight maneuver is not flexible. The inflexible opening and closing of the flying hammer leads to the decrease of the sensitivity of the governor and makes the speed of the diesel engine unstable.

Fuel consumption increases.

Idling for long periods of time can affect the engine, and frequent idling in place can also cause engine failure. If the vehicle idles in place for a long time, the fuel will not be burned sufficiently, and these unburned substances will remain in the engine, and carbon deposits will be formed over time. The impact of carbon deposits on the engine, such as engine shaking, louder noise, higher fuel consumption, weak acceleration, difficult starting, etc.

Some models will also have data on the dashboard showing fuel consumption per hour at idle, indicating that the vehicle's fuel consumption at idle will be affected by different displacements or whether the air conditioning is turned on or not.

Take an ordinary displacement of a family car as an example, the normal idle fuel consumption is about about liters per hour, and the air conditioning can reach about an hour, according to the average fuel consumption of 7 liters per 100 kilometers, it is equivalent to driving 35 kilometers of fuel consumption, the more natural the displacement of the vehicle, the higher the natural fuel consumption.

Diesel engine idling for a long time, and too little oil pressure will increase wear.

When idling, the pressure of the oil pump is relatively low, and the amount of fuel injected is small, so the grease nozzle is easy to deposit carbon and cause the needle valve to get stuck.

Supplement: Because diesel vehicles are ignited by pressure, ignition at idle speed for a long time can lead to excessive wear and tear on crankshaft pads, seat pads, and even pistons.

Agree with the upstairs: the pressure of the oil pump is relatively low when idling, and the amount of fuel injected is small, so the grease nozzle is easy to deposit carbon and cause the needle valve to get stuck.

The supplement is as follows: low fuel injection pressure directly leads to poor atomization, insufficient combustion, and waste of fuel injection to maintain the operation of the governor, in addition, the low temperature in the cylinder is easy to cause carbon deposits in the door and nozzle.

If the diesel engine runs at low idle speed for a long time, the working temperature of the engine will be relatively low, the fuel combustion will be incomplete, and the fuel that is easy to form carbon deposits and incomplete combustion will wash the cylinder wall, dilute the lubricating oil, cause wear of the piston ring, and seriously cause serious failures such as pulling the cylinder; The diesel engine with turbocharger runs at low idle speed for a long time, and the turbocharger cannot exert due power at low idle speed, consuming part of the engine's work, so that the oil and gas seeping out of the intake end of the turbine will cause the intake volute end to be oily; In addition, the low idle speed for a long time and the relatively low oil pressure will cause accelerated wear and tear of moving parts. The internal combustion engine is a heat engine, and only under the influence of coolant temperature, lubricating oil temperature, fuel combustion temperature, etc., according to the principle of thermal expansion and cold contraction, the engine will work optimally!

The idle state is the idling state of the diesel generator without any load, that is to say, in this working state, the generator set does not need to carry the load, as long as it maintains the low speed required for smooth operation.

Diesel generator manufacturers remind everyone that when running a diesel generator set, do not let it idle for too long. This is because if the diesel generator leader idles for a long time, it will reduce the quality of the fuel injection atomization and accelerate the early wear of the cylinder wall.

Because the quality of atomization is mainly related to the injection pressure, injector bore diameter and camshaft speed of the diesel generator set.

Since the injector bore size is constant, the quality of the fuel atomization depends on the injection pressure and camshaft speed.

The slower the camshaft speed, the longer the injection pressure rises, the worse the fuel atomization quality, and the camshaft speed changes with the change of diesel engine speed.

Prolonged idling can cause the diesel engine to burn too low and incomplete, which can cause carbon deposits to clog the injector holes, piston rings or lock the valves.

When the diesel engine is idling, the lubricating oil pressure is low, and the oil injection cooling effect on the top of the piston is poor, resulting in a sharp increase in wear and tear, and it is easy to pull the cylinder; It can also cause poor atomization, incomplete combustion, serious carbon deposit, and sometimes even lead to valve and piston ring jamming, cylinder liner cavitation. For this reason, some diesel engine instruction manuals clearly stipulate that the idle time of diesel engine shall not exceed 15 20min.

1. The diesel generator runs at low idle speed for a long time, and the working temperature of the engine will be relatively low and the fuel injection pressure will be low, resulting in poor diesel atomization, incomplete fuel combustion, easy carbon deposition in the nozzle, resulting in needle valve jamming, and serious carbon deposition in the exhaust tailpipe.

2. The incomplete combustion of fuel will wash the cylinder wall, dilute the lubricating oil, cause the wear of the piston ring, and cause serious failures such as pulling the cylinder.

3. Low idle speed for a long time, the oil pressure is relatively low, which will cause accelerated wear and tear of moving parts. The internal combustion engine is a heat engine, and the engine can only maintain good working condition under the influence of coolant temperature, lubricating oil temperature, fuel combustion temperature, etc.

Diesel generators generally have a permissible idle time.