In recent years, diesel engine technology has come a long way. Almost half of all passenger cars that are sold in European countries are cars with modified powertrain for diesel. Today, such motors no longer create clubs of thick black smoke, and the noise during the operation of such an internal combustion engine has long been in the past. Solar fuel power units today are not only economical, but also more environmentally friendly compared to gasoline units. These cars have higher performance in power, and the dynamic performance is ten times better. Modern motor in diesel oil is quieter. Let's look at how it turned out that such ICEs are better suited to emission standards and significantly gain traction and cost-effective parameters.
Principle of operation and layout
The power supply system of a diesel engine has a different design. Although at first glance it may seem that the internal combustion engine on a solarium does not have at least some differences from the engine on the usual gasoline.After all, there is nothing special, but the device and the internal components of the unit are the same. And in fact, the diesel engine power supply system, the purpose of which is to feed the combustible mixture into the combustion chambers, has practically no differences. Here are the same pistons, cylinders, connecting rods. But this is only at first glance.
In fact, the main and fundamental difference is the power supply system of a diesel engine. Here you can see a significant difference in the methods of formation and ignition of a mixture of fuel and air. What is in the carburetor, that in an ordinary injection unit, the mixture is not created in the cylinders, but in the intake tract of the system. The ignition of the mixture in such motors does not come from a spark, but from temperatures in the cylinder.
The diesel engine's air supply system delivers purified air to the cylinders, which is subsequently strongly compressed and then heated to 900 degrees. Fuel under high pressure with the injection system falls into the combustion chambers at the moment when the piston approaches its top dead center. The air is already quite hot, and when the fuel is mixed with air, ignition occurs.The mixture is ignited, creating an increase in pressure. This entails the noise and rigidity of such motors. So, it is possible to use cheaper combustible substances, and the motor can work even on very poor mixtures. From here and higher profitability. This scheme of the diesel engine power supply system has a higher efficiency and, accordingly, torque. The disadvantages are noise, vibration, reduced power per liter and some difficulties when trying to start cold, as well as possible malfunctions (the power supply system of a diesel engine of older models is more susceptible to poor quality fuel). However, in the new versions of cars, designed for this type of fuel, these problems are no longer there.
Device fuel systems
The diesel engine power system is a particularly important part. It should provide the supply of the required amount of fuel directly into the combustion chambers.
Diesel engine power system: device
The fuel supply process begins with a high pressure pump. It takes diesel from the tank, which is fed by a pump for low pressure.Then the necessary portions of diesel fuel are injected into the fuel line of nozzles of hydromechanical type for each of the cylinders. These nozzles under the influence of high pressure in the highways open and close when the pressure decreases.
Types of fuel pump
In nature, there are only two types of high pressure pumps. This is an in-line pump with a multi-plunger system and a distribution pump.
This pump is represented in several sections by the number of cylinders. Each section has a separate sleeve and plunger. Plunger drive - cam shaft, which rotates from the power unit. Such mechanisms are arranged in a row, and therefore have a corresponding name. They are currently not actually used in constructions. These devices do not cope with modern requirements for noise and environmental friendliness. Also, the level of pressure that such pumps can create depends on the number of revolutions of the crankshaft. The power supply system of the Kamaz diesel engine has a pump of this type.
Distribution type device
A more modern power supply system for a diesel engine and injection pump of a distribution type allows you to create higher pressure values for the injection system.In addition, such pumps fully comply with all current standards for toxicity and noise. This diesel engine power supply system is capable of maintaining the required pressure in the highways and power systems under different operating conditions of the engine.
Distribution pump of high pressure is equipped with one plunger, which performs translational motion for forcing the fuel mixture, and also rotates in order to improve the distribution of fuel in the injectors. These devices are compact, uniform supply, excellent performance. However, in order for these devices to work more efficiently, you need to monitor the cleanliness of diesel fuel. Diesel oil works as a lubricant, and the gaps in the parts of the parts are very small.
The main purpose of the injectors is to spray the mixture into the combustion chamber. How much combustible mixture will be sprayed is estimated by the fineness and uniformity of spraying, uniformity, cut-off, and support of the necessary pressure.
The nozzles are divided into two groups according to the design features. There are open and closed parts. The most important element of this site is the sprayer.This part is selected depending on the type of combustion chamber and how a mixture of diesel and air is created.
In the nozzle of a closed version, the pressure that is necessary for spraying the mixture directly depends on the ratio of the areas of the plunger cross-sections and the nozzles in the nozzle. The pressure, which will be enough to open the nozzle, is determined by the force needed to tighten the spring, which creates a load on the locking needle.
In the past, nozzles with hydraulic control were widely used. Diesel fuel is supplied to the nozzle via a pipeline under high pressure. The pipeline, in turn, is connected to the choke. Inside the fitting has a filter in the form of a grid. When the fuel has passed the filter, then it passes into the internal channels of the nozzle and the sprayer. The power supply system of the Kamaz 740 diesel engine is equipped with just such nozzles.
Directly injection begins when the pressure that the high pressure pump creates increases, causing the spring to compress and the mixture to the nozzles open. When the pressure drops, the needle drops and closes the nozzle. Here the injection ends.
Spray nozzles of this type have several holes. The total number of holes depends on how the blending is performed. Closed nozzles have an advantage. Here is better spraying, especially at lower speeds. Less diesel flows, they are much easier to adjust.
For passenger cars, these nodes were mostly undivided. The injection process is not in the cavity above the piston, but in a special chamber in the cylinder head. In this case, there were two types of process of mixing. It is antechamber (or prechamber) and vortex chamber.
When using the latter type of process, combustion begins in a separate chamber, which has the shape of a ball. At the time of the start of the stroke, the pump delivers the air mixture to the prechamber and a vortex forms in it. Then the injection takes place and is mixed with air.
So, the combustion process consists of two stages. This has significantly reduced the load on the pistons, and the sound of the engine has become much softer. The lack of such motors is an increased consumption due to losses on the surface of the combustion chamber, huge losses due to the flow of air into a separate chamber, as well as the mixture getting into the cylinder. Also, the starting quality of the power unit is much worse.
In motors with an undivided chamber, fuel is injected directly into the cylinder cavity, in turn, the combustion chamber is located at the bottom of the piston. A similar scheme has recently been used on units with large volumes, but low revolutions. These motors turned out to be much more economical than units equipped with a divided camera system. But using them on small engines was fraught with difficulties in organizing the process, as well as high levels of noise and vibrations during acceleration.
Today, the diesel engine power supply system, the device of which we examined, is electronically controlled, so the dosing process is significantly optimized in units with an unseparated chamber, as well as decreased noise during operation.
Common rail system
Due to some tightening of environmental standards and the emission of toxic substances, which were imposed on the power units on diesel, the diesel engine power supply system has undergone some changes. Let's talk about this in more detail.
What it is?
Common Rail is an injection system that can be described as the injection of a mixture of air and diesel under fairly high, but atmospheric pressure. As a result, with this scheme, you can reduce the flow, and the power will increase.
Of course, this is not all that this scheme is capable of. Managed to reduce noise and increase torque. The new system has become particularly popular. Today, every second machine is equipped with this very scheme.
The disadvantages of the system are the high requirements that are imposed on the quality of diesel fuel. If even the smallest particles penetrate the power system, then the nozzles with control from the ECU may fail.
The power supply system of a diesel engine tends to wear out and sometimes fails. Often this may be due to the failure of the electronics and fuel lines.
The main faults are blockages and depressurization. Also sometimes there are malfunctions in the operation of the low pressure pump.
So, we found out what device the diesel engine fuel supply system has. There are many more standard faults, but this is a topic for another article.