Diesel Engine Injector Pump: Device and Operation Principle

The requirements that are imposed on modern diesel engines in terms of power, economy and environmental friendliness are getting higher. In order to satisfy these requirements, a good mixture formation must be ensured. For this, the engines are equipped with modern and efficient fuel injection systems. They are able not only to ensure the smallest spray at the expense of higher pressure, but also precisely adjust the injection timing and the amount of fuel supplied to the cylinders. Such a system exists and fully meets all those high requirements. This is a diesel engine injector pump . It is a separate injection element for each cylinder in the engine. The part is controlled by an electronic unit.

Diesel Ideas

About the creation of a node in which the injector and the fuel pump would unite, the very creator of these engines, Rudolf Diesel, was thinking.

This would allow us to avoid fuel lines and high-pressure pipelines, thereby increasing the injection pressure. But in the days of Diesel, there were still no such opportunities that exist today.

Description of the system

The diesel engine injector pump is a fuel pump and an injector that is integrated into one unit. As in the injection pump with injectors, injection based on these elements can perform certain tasks. The system creates sufficient pressure, delivers a certain portion of the fuel mixture at the right time. A separate pump is provided for each combustion chamber. That is why now you can find engines where there are no high-pressure fuel lines, that is, on power units with injection pump.

Historical facts

This injection system is not a new development. The diesel engine injector pump was installed on cars in the late 30s. For the first time, the design was tested on diesel engines for rail, sea, and cargo vehicles. All this technique was united by one - a small speed. The features of these engines are in the presence of a separate pump for each cylinder and in the short pressure lines that go to the injector. The actuator for the elements is the pushers and buffers.

Serially began to apply such systems on trucks since 1944. On passenger cars - since 1988. In 1938, the company Detroit-Diesel, which then belonged to the concern General Motors, was created the first such unit, which used the power system of a diesel engine with pump injectors. Despite the fact that the device was developed in the US, designs of this type were also developed in the USSR.

The first YAAZ-204 engines were equipped with such nozzles as early as 1947. But these sites were produced under the license of Detroit-Diesel. This power unit, and then a modified six-cylinder engine was produced before 1992.

In 1994, the device and operation of the diesel engine injectors were noticed by Volvo engineers. The company produces the first truck FH12 with injectors of this type. Then the same units will begin to equip their trucks "Scania" and "Iveco."

Among passenger cars for the first time this system was used on "Volkswagen". The pump-injector of the diesel engine "Volkswagen" appeared in 1998. In the late 90's, engines with such a system occupied 20% of the automotive market.

Device

So, let's see what a diesel injector pump is. The device is extremely simple. In the body of the unit there is directly a nozzle, a dispensing unit, and also a power unit. Due to this power drive, the injector pump has certain advantages over traditional systems. Thus, the time of motion of a combustible liquid under high pressure is significantly reduced. Hydraulic efficiency also increases and weight decreases.

The nozzles of the latest generation are equipped with pumps capable of producing a sufficiently high pressure (up to 2,500 bar). They can respond instantly to the commands of the ECU, which collects and analyzes the current information from external sensors. According to these data, the required amount of mixture and the injection time are determined. This makes it possible to obtain optimal power values for given operating conditions. In addition, the nodes help to save diesel fuel, which helps to minimize harmful emissions into the atmosphere and contribute to reducing noise from the running engine. Finally, the device is very compact and can be placed in the cylinder head. There you can also install other parts and components.

The nozzle is designed in such a way as to ensure the most efficient mixture formation. To do this, the engineers have envisaged phases - this is a preliminary, basic and additional injection. Preliminary gives a smooth combustion at the moment of the main phase, when a qualitative formation of the working mixture is provided in different operating modes of the engine. An additional one is necessary for the regeneration processes in the particulate filter.

Principle of operation of a mechanical injector

The diesel engine injector pump is installed directly into the cylinder head. There are four special cams on the camshaft. They serve to start the injector drive. With the help of the rocker arm, the force is transferred to the injector pump by means of plungers.

The drive cam has a special profile that provides a sharp upward lift, and then a slow lowering of the rocker arm. When the last one rises, the plunger is quickly pressed down. This creates the right pressure. When the rocker is lowered slowly, the plunger goes up. Due to this, the fuel enters the cells with high pressure without air bubbles.

The process of injection is carried out when the control voltage from the computer to the solenoid valve is applied.

Injection phases

Let's consider in more detail the principle of the pump-injector of a diesel engine. When, under the action of the rocker, the plunger moves downward, the combustible mixture flows through the channels into the nozzles. When the valve closes, the diesel flow is cut off. The pressure starts to grow. When it reaches a level of 13 mPa, the spray needle overcomes the spring force. After that the preliminary phase of injection will begin.

Once the valve starts to open, the pre-phase ends and the fuel mixture is routed through the supply line. The pressure begins to fall. Depending on the mode of operation of the engine, one or two preliminary phases can be performed.

When the plunger moves down, the cycle of the main injection starts. The valve closes again, the fuel pressure rises again. When the level reaches 30 mPa, the spray needle overcomes the pressure and rises, thereby triggering the injection process. The higher the pressure rises, the more fuel will be compressed. The amount of diesel and air that can get into the cylinder increases.

Maximum feed (and it is performed when the motor is running in peak power mode) is performed at a pressure of 220 mPa. The valve opens the main injection stage. The pressure drops, the needle closes.

The additional injection phase is executed when the plunger further moves downward. The principle of operation of the device at this stage is the same as the main injection. More often the algorithm is performed in two stages.

If you consider the device injector pump TDI diesel engine, it can be equipped with a sensor that monitors the lifting of the needle. The needle position is required by the control unit, where the fuel pumps are also electronically controlled.

Benefits

Whereas in the Common Rail system a battery injection is used, the injector pump supplies the fuel mixture at a higher pressure due to the absence of long lines.

They can often collapse during the operation of the car. This is a weak link in classical food systems. The injector pump allows more fuel to flow into the combustion chamber. In this case, spraying will be more effective. Motors equipped with such units are more powerful.

In addition, engines with such an injection work less noisily than their analogs. But with the "Common Rail" or injection pump injection pump will still be more compact.

disadvantages

But there are also disadvantages. The most serious minus is the high demand for quality fuel. The slightest clog is enough to stop the system from working. The second minus is the price.

It is almost impossible to repair this exact node outside the factory conditions. Another disadvantage is that under the influence of high pressure these nodes often break the landing nests in the engine block.

How to service the injector pump?

Apparently, these nodes are very demanding for the quality of the diesel, and it is far from high in our country and in the CIS. In order not to often change this expensive element, it is recommended to regularly change fuel, air and all other filters, purchase original consumables.

About washes

Often, car owners are interested in how to rinse the injector pump on a diesel engine. Experts do not recommend rinsing - this is not good for any injectors. It is better to replace the filters and refuel at proven gas stations.

Washing on the stand will do, if there is a poor-quality spraying - an unstable idling and similar problems. Rinse in an ultrasonic bath is allowed when the needle is completely stuck. If the nozzle pours, then nothing will help here. For washing you can use the currently popular means "LAVR" and "VINS".

In general, if the injector does not work, it is better to carry out maintenance and replace parts that are out of order. Washing helps only if the site is at least somehow, but works.

Conclusion

So, we found out what the injector pump of a diesel engine is and what its device is. элемент системы питания дизельных ДВС. As you can see, this is an integral element of the diesel engine power system. It has a more technological design, but it is very demanding on the quality of fuel.