Bosch launched the first common rail system in 1997. the system is named after shared high-pressure reservoir (common rail) that supplies all the cylinders with fuel. With conventional diesel injection systems, the fuel pressure has to be generated individually for each injection. With the common rail system, however, pressure generation and injection are seperate, meaning that the fuel is constantly available at the required pressure for injection.
We at Diesel Works offer quality repairs to the common rail system in a financially efficient method. the work we perform carries a 1 year warranty which is the same as if you were to purchase a new injector from the agents, however the cost of a repair usually comes in at a fraction of the cost to replace maling it an attractive option.
Common Rail System for Commercial Vehicles
The CRS consists of:
- High pressure Pump
- High-pressure accumulator (rail)
- Electronic Control Unit
- Injector
Types
The Common Rail System (CRS) is an accumulator-type injection system. In contrast to other injection systems though, high-pressure generation and fuel injection are completely independent of each other. The Common Rail System therefore provides more freedom in the adaptation of the injection process. This makes it possible to develop quiet-running, economic engines featuring outstanding dynamic response.
Injectors
The injectors are installed in the engine's cylinder head, and have the same function as nozzles and nozzle holders on the previous injection systems. The main injector components are:
- Hole-type nozzle
- Hydraulic servo-system
- Solenoid valve
Injector functions
The forces required to open and close the nozzle needle cannot be generated by the solenoid valve on its own. The nozzle needle is therefore indirectly triggered via a hydraulic force-amplification system.
With the solenoid valve closed, the complete chamber volume and the rail are at the same pressure. The nozzle needle is forced against its seat by a spring.
When the solenoid valve opens, fuel flows from the valve control cavity and into the fuel return. The feed throttle prevents complete pressure equalization, and the pressure in the cavity drops. The excess pressure in the chamber volume overcomes the spring force and lifts the needle so that injection can start.
The solenoid valve is no longer energized and closes the opening to the fuel return. The force applied to the control plunger increases along with the increasing pressure in the valve control cavity. The needle closes and injection stops.
Common Rail System (CRS) for passenger cars
Applications: Passenger cars, light-duty commercial vehicles
Power output: 30 kW/cylinder
No. of cylinders: 3...8
Control: Electronic, electrical, solenoid valve, or piezo actors
Injection pressure: 1350 bar (1st gen.), 1600 bar (2nd gen.), 1800 bar (3rd generation with piezo injectors)
Injected fuel quantity: up to 90 mm3 per stroke
Injectors
The injectors are installed in the engine's cylinder head, and have the same function as nozzles and nozzle holders on the previous injection systems. The main injector components are:
Hole-type nozzle, hydraulic servo-system, solenoid valve or actuator.
Injector functions
The forces required to open and close the nozzle needle cannot be generated by the solenoid valve on its own. The nozzle needle is therefore indirectly triggered via a hydraulic force-amplification system.
With the solenoid valve closed, the complete chamber volume and the rail are at the same pressure. The nozzle needle is forced against its seat by a spring.
When the solenoid valve opens, fuel flows from the valve control cavity and into the fuel return.The feed throttle prevents complete pressure equalization, and the pressure in the cavity drops. The excess pressure in the chamber volume overcomes the spring force and lifts the needle so that injection can start.
The solenoid valve is no longer energized and closes the opening to the fuel return. The force applied to the control plunger increases along with the increasing pressure in the valve control cavity. The needle closes and injection stops.