Injection diesel engine: what it is and how it works
1. HOW A DIESEL ENGINE WORKS
2. DIRECT AND INDIRECT INJECTION DIESEL ENGINE
• What is direct injection?
• What is indirect injection?
3. HOW COMMON RAIL DIESEL INJECTORS WORK
4. THE BENEFITS OF COMMON RAIL DIESEL INJECTION
5. COMMON RAIL INJECTORS: MODELS AND FEATURES
• What are solenoid injectors?
• What are PIEZOELECTRIC injectors?
6. THE IMPORTANCE OF CLEANING AND MAINTAINING DIESEL INJECTORS
7. REDAT: QUALITY SPARE PARTS FOR DIESEL INJECTORS
No matter how much the diesel engine has evolved over time, diesel injection remains key to the engine’s operation and to the basic principle of its operation. Most research, in terms of innovation and optimisation, has been carried out specifically on diesel injection. Following these studies, the injection system that fuels the combustion of diesel, on a technical level, is the area which has changed the most over the years.
1. HOW A DIESEL ENGINE WORKS
Diesel-powered engines are generally defined as “spontaneous combustion” engines. This is because the fuel, i.e. the diesel, does not need any external intervention to ignite, unlike petrol.
The operation of a diesel-powered engine follows precise stages:
1) Suction: the air is drawn in from the outside, filtered to remove impurities and introduced into the compression cylinder
2) Compression: the air is compressed by a piston which moves inside the cylinder thus significantly increasing the temperature of the air
3) Combustion: the fuel is then injected into the cylinder via the input system (the injector) which is operated by injectors and once the diesel comes into contact with the heated air, it ignites spontaneously
4) Exhaust: as the piston moves up, it pushes the exhaust gas towards another system which disposes of and expels it.
2. DIRECT AND INDIRECT INJECTION DIESEL ENGINE
What is direct injection?
To date, direct injection is the most widely used system on cars on the road. It involves spraying diesel fuel directly into the combustion chamber inside the compression cylinder.
This mechanism guarantees outstanding overall efficiency and optimised performance for the entire engine. Over the years, there have been many technical innovations that have improved this system, the latest being the Common Rail, the key evolution for this type of engine.
Unlike the injector-pump system, which pre-charges the diesel pressure inside it, the Common Rail consists of a single pipe from which all the injectors branch. Inside this “rail”, the fuel reaches very high pressure levels and guarantees greater efficiency thanks to multiple fuel nozzles.
What is indirect injection?
This system, which is now obsolete, involved spraying fuel into a combustion pre-chamber, artificially heated by dedicated spark plugs on which an electrical heating element was installed. The main disadvantage of the indirect injection system was that the combustion was much less efficient compared to the one obtained by direct injection.
3. HOW COMMON RAIL DIESEL INJECTORS WORK
The Common Rail is now the most commonly used fuel injection system in diesel engines. This system gives the engine more control over the fuel (the diesel) injection pressure, thus guaranteeing a more efficient, safer and reliable combustion process which optimises engine performance.
Once the fuel has been pressurised in the injection pump, it is stored in the Common Rail system (or accumulator) and then sprayed into the combustion chamber through multiple injectors which branch out of one pipe.
Diesel injectors must be adjusted within the set limits based on the fuel pressure and the time required to deliver the fuel. A Common Rail diesel engine is not, therefore, affected by the engine speed, has multiple injectors to deliver fuel to the engine at different pressures and times, thus resulting in greater flexibility in terms of power level, fuel consumption and engine emissions.
4. THE BENEFITS OF COMMON RAIL DIESEL INJECTION
- High fuel pressure inside the engine
- High injection precision via the diesel injectors
- Total control of the diesel injection pressure, timing, speed and quantity of the fuel
- Reduction of engine polluting emissions
- Performance optimisation and fuel economy
- Greater power and reduced noise level
By succeeding in measuring the fuel injection pressure more accurately, the Common Rail injector is able to regulate the performance of the entire engine according to the required level of combustion.
The right fuel, at the right time: this is the key to the high efficiency of diesel engines with Common Rail injectors. The performance of these engines is optimised by the Common Rail injectors which provide only enough fuel and injection pressure when required for combustion.
5. COMMON RAIL INJECTORS: MODELS AND FEATURES
In Common Rail diesel engines, there are different types of injectors with specific structural characteristics, suitable for different applications and types of vehicles.
What are solenoid injectors?
Solenoid injectors regulate the fuel injection by means of a control valve which opens and closes by magnetic force, using a solenoid valve located on the actuator.
What are piezoelectric injectors?
Piezoelectric injectors have a higher reactivity compared to solenoid versions because they use piezoelectric elements located on the actuators. The piezoelectric components work by converting the changes in applied voltage into expansion and contraction (i.e. movement). These injectors feature a built-in piezo stack which covers all the piezoelectric elements.
6. THE IMPORTANCE OF CLEANING AND MAINTAINING DIESEL INJECTORS
impurities are deposited over time in all fuels, including diesel, that can cause malfunctions or impair injector performance and vehicle fuel consumption.
It is, therefore, necessary to recognise the signs that can indicate when it is time to clean the injectors. Here are some signs:
- difficulty starting the engine;
- increase in fuel consumption;
- drop in performance;
- engine stalling when idling;
- black exhaust fumes.
Cleaning diesel injectors is a delicate matter that should not be underestimated, and we should all make sure we have the right tools at hand to maintain or replace them.
This is why REDAT has produced a comprehensive guide to cleaning diesel injectors, which you can find here https://www.redat.com/news/news/cleaning-of-diesel-injectors, but you can, however, contact us at +39 011 979 1111 or via email at [email protected] or [email protected] for all your professional Common Rail injector needs.
Injector maintenance can sometimes require more than just cleaning. There comes a time when the injector components need replacing - due to wear and tear or damage - and it is, therefore, always advisable to know who to turn to for high-quality spare parts.
7. REDAT: QUALITY SPARE PARTS FOR DIESEL INJECTORS
REDAT is a leading manufacturer of diesel injection systems both in Italy and abroad and specialises in the manufacture and sale of high-quality spare parts for diesel injectors. We offer an enviable quality-price ratio and the guarantee of an excellent result in terms of the performance of the part and the injector as a whole reconditioned with our products.
Thanks to our many years of experience in the production of spare parts for injectors, injection pumps, reconditioned injectors and equipment for repairing diesel injectors, we can fulfil customer requests by providing a standard of quality that is comparable to original parts at competitive prices.
Our products cover most of the injection systems on the market for all industries, including the automotive, industrial, marine and agricultural sectors. You can find all the spare parts for the main brands in our aftermarket catalogues: Caterpillar-Perkins, Denso, Bosch, Delphi, L’Orange-MTU, Cummins, Unit Injector, Siemens.
From our e-commerce you can know the availability and price of each product, as well as view the interactive explosions and the product sheet of each injector. If you do not have an Account enabled to view prices, you can send a quotation request, or contact our offices to request a Reserved Account directly on the REDAT website.