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Misunderstandings of EFI and Direct Injection Diesel Engines.


The difference between direct injection and electric injection engine Misunderstanding of electronic control and direct injection diesel engine

Recently, many car owners have inquired about the difference between direct injection and Shenji, which is basically an intuitive feeling, but professional experts disdain to make a sound. Therefore, Li Xia of Merit maintenance department will simply talk about "direct" based on his years of maintenance experience. The difference between injection and EFI, the misunderstanding of electronic control and direct injection diesel engine”

Simply put, the direct injection machine is a direct injection prison burning chamber: an electronic injection machine is a direct injection machine with an electronic computer controlled fuel system.

The so-called direct injection engine is the direct injection combustion structure, which means that the combustion structure of the engine is a direct injection type, and the corresponding non-direct injection type - such as: pre-chamber type, swirl type, etc.: non-direct injection engine is The popular colors of the last century, many, hundreds of horsepower diesel engines are non-straight
Injecting the combustion chamber, which is only occasionally seen on some low-power machines, such as the Mitsubishi 4M40 engine of the CAT small excavation [305.5], and on the 307D, the combustion chamber has been changed to direct injection;

The combustion chamber structure of the direct injection and non-direct injection engines is different, and the injector structure is also different. The biggest difference is: the direct injection combustion chamber structure machine does not have a T combustion chamber on the cylinder head. Formed at the top of the live cold with the cylinder head plane, rather than a direct indirect junction
The cylinder head of the machine is equipped with a combustion chamber, that is, a pre-combustion or swirl [auxiliary combustion chamber], which also forms a combustion chamber together with the combustion chamber [main combustion chamber] at the top of the cylinder head.

Another feature is that the indirect fuel burners are all single, the injection pressure is low and the burning speed is slow, so the combustion is more thorough. Lower: The oiler of the direct injection engine is
The so-called multi-hole injector has high injection pressure, high fuel efficiency, low fuel consumption, but high T-adding precision and high manufacturing cost. Currently, high-speed diesel engines used in construction machinery [corresponding to low-speed and medium-speed diesel engines, not in this case. ] Basically this structure, referred to as direct injection machine:

The indirect injection type was a popular variety before the 1980s. Even the famous Isuzu TD70 is a combustion chamber truck engine with this structure. , at the injector installation part
There is a corresponding combustion chamber pre-combustion chamber or swirl chamber for the fuel to be burned in advance so that the main combustion final chamber can carry out good continuous combustion. It is characterized by soft burning and low noise. The fuel injector is a single hole. It is easier to add, and it is more suitable for low-quality oil. In the last century, there were many fuels.
Diesel engines [especially military engines], gasoline and diesel can even drink alcohol without getting drunk! [Older colleagues can still remember that there was a 2125 diesel engine, which was a gasoline engine when it was started, and then switched to diesel engine operation. ], a typical example is the original Dongfanghong
The 4125 diesel engine is a non-direct injection machine: but the fuel efficiency is low and the fuel consumption rate is high. For example, the 195 series single-cylinder diesel engine that everyone has seen is a vortex non-direct injection engine, and its fuel consumption rate is 225a/hp per Small
If anyone can remember China's first industrial tractor, the Honghongqi 100 produced in Anshan, it is a diesel engine with a pre-combustion chamber structure; while the direct-injection 6100 diesel engine in the same period is a direct-injection diesel engine, and its fuel consumption rate is 185g/ per horsepower.hour;

Electric engine is the abbreviation of dry electronically controlled engine. It is divided into two types of internal combustion engines, namely gasoline engine and gasoline engine [passenger cars are now all electronically controlled gasoline engines] Construction machinery basically uses diesel engines, it should be described In order to electronically control some oil generators, that is, according to the operating conditions, use the on-board calculation
The engine controls the diesel engine to implement the operation of the diesel engine, you can understand it? The direct injection and the electronic injection machine are actually not the same concept:

However, the electronically controlled diesel engine is originally a direct injection prison combustion chamber, which is what everyone calls a direct injection machine!

The first generation of electronically controlled direct injection machines is based on the traditional diesel engine fuel system, with some modifications, many just use stepper motors to replace the mechanical governor for fuel injection control, which is far from perfect, but some have begun to be adopted. The signal of the machine running to feedback the working condition information, I do not have
The body says the model anyway, as long as you see a thick wire harness on the fuel injection pump governor that is introduced into the interior, that's it

The second-generation electronically controlled diesel engine has already completed the high-pressure common rail machine that everyone knows, that is: on larger models of diesel engines, instead of common rail technology, electronically controlled pump-nozzle technology is used, that is, mechanical drive, electric The control nozzle technology is used by many diesel engine manufacturers, such as: Volvo, Detroit
Lil Cummins CAT, etc.: The engine C-C9 of CAT330CD discussed by everyone is another electronic control method. It is not a high-pressure common rail system or a mechanical drive form, but a unique wave pressure drive, an electronically controlled oil finisher. , belongs to the dry low pressure common rail [there is only

Pressure around 500Kna] High-pressure injection technology, which is relatively load-free, should be considered the most advanced, but it also brings about the problem that the more sophisticated and complex, the more difficult to maintain.