Common Rail Technical Paper
20Pages

Common Rail Design & Field Experience Engineering the Future - since 1758

Introduction MAN Diesel & Turbo Common Rail MAN Diesel & Turbo is the world’s leading designer and manufacturer of low and medium speed engines – engines from MAN Diesel & Turbo cover an estimated 50% of the power needed for all world trade. We develop two-stroke and four-stroke engines, auxiliary engines, turbochargers and propulsion packages that are manufactured both within the MAN Diesel & Turbo Group and at our licensees. The coming years will see a sharp in- increasingly important success factor continuous and load-independ­ nt cone for marine and power diesel engines. trol of...

System Description General considerations Control valve Rail unit High-pressure pump Injection valve Non-return valve Valve block with pressure-limiting valve and flushing valve Throttle valve The MAN Diesel & Turbo CR system Using just one pressure accumulator by these drillings are unavoidable. (common rail) for large bore diesel tion with HFO in accordance with spec­ engines, extended over the entire counter-measures therefore increase engine length, is problematic for the proportionally with the increased following reasons: inner diameter of the rail in larger ­ of up to 150°C (to...

Injection valve Control valve Rail unit High-pressure pump Throttle valve Valve block with pressure-limiting valve and flushing valve Non-return valve excessive length by connecting it to more compact design of the CR units ensures improved uti­ lization of avail- the high-pressure pump at one point able space in the engine, which is ben- only will result in deviations in eficial for assembly. It also has advan- ­injection quality. handling of spare parts. It is therefore reasonable to separate the accumulator into several rail units of Based on the concept of segmented rails, MAN Diesel &...

Layout and Functionality Well thought-out and proven Injection timing Fig. 3: CR injection system – general layout and functionality MAN Diesel & Turbo Common Rail – Design & Field Experience Formation of injection press

Fig. 3 shows the hydraulic layout of This design means the tube itself requires will then suitably meter the fuel quantity the patented heavy fuel oil CR injec- no drilling and is therefore highly pres- supplied to the high-pressure pumps. sure-resistant. To guarantee uniform fuel injection, pressure fluctuations in the system must remain at a very low level. nents for fuel supply and injection tim- From the fuel system, the fuel supply is This is achieved by using rail units of ing control. The fuel flow leads from the fed through electromagnetically activat- optimum volume, several (two...

The non-return valve 13 (Fig.  also 3) system is flushed by circulating pre- In the event of an emergency stop, main- heated HFO from the low-pressure fuel tenance, or a regular engine stop, the pressure system into the cylinder, e.g. system. For this purpose, the flushing flushing valve 11 provides pressure relief in case of nozzle needle seizure. A valve 11 , located on the valve block 10 for the whole high-pressure rail system. arranged pressure-limiting valve on the valve block 10 protects the at the end of the rail units will be opened pneumatically. Any residual high pres- The...

Advantages Decisive criteria for operators Fig. 8: Common rail system MAN V32/44CR The principal advantage of CR injec- that the injection valves are only pres- tion is the flexibility gained by sepa- surized during injection. This avoids un- nology, and thus an optimized com- rating pressure generation and injec- controlled injection, even if a control bustion process, have the best poten- tion control. valve or injection valve is leaking. tial to meet more stringent emission Engines equipped with this CR tech- regulations that may be imposed in fuMAN Diesel & Turbo has kept its CR The CR...

Safety Concept Established method, smart features Safety in design and operation is one of the most important considerations, especially for marine engines. To ensure that all possible failures are covered by the CR safety concept, MAN Diesel & Turbo has carried out an extensive failure mode and effects analysis (FMEA) process. On the basis of the FMEA, measures for failure detection and error prevention have been developed and integrated into the system, but only after the successful completion of extensive validation tests on the test rig, which are vital for any new technology concept....

Electronics Fully embedded into The challenge for electronics was to design a simple and redundant CR system for singleengine main-propulsion applications. The result of this research was a flexible and reliable CR solution, which has meanwhile been extensively proven in practice. duration. After each engine stop, the systems, classification organizations control function changes between the ­ chine interface (HMI). For multiple en- require a fully redundant system lay- two connected injection modules while gine installations, a non-redundant de- out. The injection electronics is there-...

Development Process Design, simulation, and testing The complete development process ensures the market launch of a new Concept, Design, FMEA product with a high level of maturity, so a well-proven product with low technical risk will be available from start of series production. With con- Design loop tinuous development after series reEngine test bed (> 1000 rhrs) lease, experience from the field is taken into account. Type approval (classification) Fig. 10 gives a general impression of the Field test (> ~ 12000 rhrs) development process which the new MAN Diesel & Turbo product needs to...

Hydraulic optimization and endurance testing on injection test rigs Fig.  illustrates the comparison be12 Fig. 14 shows the measured pressure tween the simulation and the test ahead of the injection valve for three As mentioned above, heavy-fuel opera- results to demonstrate the solid cor­ different versions of the control valve, tion is a major challenge for all electron- relation between simulation and mea- compared to the injection pressure ically controlled injection systems. MAN surement. However, the simulation was curve of the conventional injection Diesel & Turbo therefore uses test...