High-Performance and Fuel-Efficient Common Rail Systems by Liebherr Common Rail Systems by Liebherr 2 Common Rail Systems by Liebherr The operational spectrum of Liebherr Common Rail systems covers inroad and onroad machines as well as stationary applications and includes the medium and heavy duty ranges. The highly flexible system is equally reliable for series inline and V-engines and supports compliance with applicable and future emissions stand- ards. These include the offroad standards USA EPA CARB Tier 4, 97 / 68 EC Stage IIIA, Stage IV and Stage V, as well as the onroad standards Euro V and Euro VI. The injection technology developed in-house has already demonstrated its success in nearly 400 engine variants, in diesel engines made by the Liebherr Group as well as in units from other manufacturers. Advantages Liebherr's great engineering and sys- the harshest environmental conditions tem expertise as well as its high de- ensure the ultimate high-performance gree of vertical integration provide high and reliability of injection systems over flexibility in integration of Common Rail a long service life. Precision multiple systems in various engine variants. Dec- injection at pressures up to 2,200 bar ades of experience in the development guarantees low emissions and low fuel and production of diesel engines for consumption. Ultimate Comprehensive quality high-performance assurance Optimal fuel efficiency for your engine For lifetime reliability Engineering System expertise solutions State-of-the art methods for stable Your partner for complete integration power and high load capacity Precision parts from in-house production Flexibility for every customer requirement Common Rail Systems by Liebherr 3 Ultimate high-performance Liebherr Common Rail systems not only deliver a high injec- soot particles and NOx emissions already inside the engine. tion pressure of 2,200 bar, but also stable multiple injection The most complete fuel combustion possible ensures maxi- per combustion cycle. Therefore, it is possible to minimise mum energy use, which thereby reduces fuel use. 4 Common Rail Systems by Liebherr Optimal fuel efficiency for your engines High degree of efficiency Minimum switching leakage Efficient energy conversion from the high pressure generation Liebherr injectors are set apart by their very small amount up to the injection pressure is decisive for a high degree of of switching leakage. In the case of system injectors for en- efficiency of the injection system. Liebherr uses many design gines with a capacity of up to 2 litres per cylinder, at full load measures to connect the injector nozzles throttle-free, if pos- it is a maximum of 30 ml / min. This provides the following sible, to the high pressure pipe system, for example hole filters. advantages: • higher degree of efficiency and therefore lower Stable multi-point injection fuel consumption With multiple injection, pre-injection is very important for quiet • lower leakage temperatures, therefore lower cooling engine operation, the main injection is important for optimal requirements power development and maximum torque, and post-injection • good tolerance of various fuel qualities is important for reduction of emissions. • optimal preconditions for start-stop operation – as the system pressure is still maintained when the engine is The 3-way servo valve ensures that the injection spray is shut off, restarting is accelerated established moderately. Finally, the injection process is com- pleted by closing the nozzle needle very quickly. This results in a very clear boundary for the individual injections and a precisely measured fuel amount – both of which are deci- sive factors for an optimal combustion process, low fuel con- sumption and minimum raw emissions. 3-way servo valve Quantity engine characteristic map Injection rates The injector has an additional hydraulic At pressures from 200 to 2,200 bar, the The chart shows the fuel supply during the intermediate valve with which the nozzle quantity characteristic curves of the Liebherr injection process at various opening speeds needle can be closed very quickly and, injectors excel by very high linearity, i.e. of the servo valve depending on a set pres- independently of that, can be opened with uniform injection amounts. sure of between 200 and 2,200 bar. Closing adjustable speed. takes place independently. Injection rate Injection Quantity per stroke Time of current Time Common Rail Systems by Liebherr 5 Engineering expertise Simultaneous engineering concepts are used in development stant optimisation of the system and its modules. This en- of the Liebherr injection system. Modern development tools ables Liebherr to provide its customers with a reliable state- such as the Finite Element Method (FEM) and Computational of-the-art complete system. Fluid Dynamics analysis (CFD) contribute towards the con- 6 Common Rail Systems by Liebherr State-of-the art methods for stable power and high load capacity Product validation Engineering methods All components in Liebherr Common Rail systems are sub- Many components of a fuel injection system are subjected to ject to a thorough and comprehensive validation program. cyclic loads. When testing with FEM, particular emphasis is This is oriented on excellent system reliability and availability placed on determining and then optimising fatigue resistance. under demanding environmental conditions, as well as to- wards a long product service life. All Common Rail system components are also inspected It contains advanced models for damage modelling that use intensively by calculation engineers with CFD analyses to accelerated testing in endurance tests, mechanical strength model flow effects inside components and incorporate the tests, temperature tests and environmental tests to repro- findings in the design. duce the ageing process of components. Sophisticated statistical data analyses are used to ensure that the selected samples are representative for all components. Field trials are also a key element of the validation process. They are primarily used for verifying simulations of the under- lying data and accordingly modifying the validation tests. Development test bench Finite Element Method (FEM) CFD simulation Liebherr Common Rail systems are subject The FEM design not only determines fatigue CFD analyses made minimisation of the effect to comprehensive endurance tests on special resistance, but stress and deformation are also of cavitation erosion on nozzle needles and test benches during development. Acceler- inspected under operating and peak loads, nozzles possible; cavitation erosion results ated testing examines the ageing process of and component geometries are adapted from the very high flow speeds. the system and single components. accordingly. Common Rail Systems by Liebherr 7 Precision parts from in-house production Liebherr Common Rail and engine management systems are Lindau, Deggendorf is the competence centre for production developed and manufactured at three sites in Switzerland of micro-precision parts. The assembly lines for injectors and and Germany. Whilst engine control units are produced in high pressure pumps are in Bulle, Switzerland. 8 Common Rail Systems by Liebherr Flexibility for every customer requirement Micro-precision manufacturing Assembly monitoring The geometry of the nozzle hole and its process-reliable On the assembly line, which is configured for series produc- manufacturing are especially important for the required fine tion and largely automated, all manual process steps are fuel nebulisation. Therefore Liebherr has introduced Electri- monitored by the system technology. Operating errors are cal Discharge Machining (EDM) and Hydro Erosive Grinding practically eliminated by the intelligent quality management (HEG) manufacturing processes at a dedicated micro-preci- system (Poka Yoke). sion manufacturing site. High parts availability Assembly in a clean room Large investments in modern production and test facilities Extreme care is necessary during assembly to ensure the enable fast start-up times for series production. For maxi- functional capability of the high-precision parts in the Com- mum flexibility, the latest knowledge about material flow and mon Rail system. The parts must be absolutely dust and other process sequences were taken into account when oil-free, therefore they are cleaned in four separate washing constructing the facilities. High parts availability provides the cycles. High pressure pump, high pressure connector and foundation for optimum customer support. injector components are assembled in a class 7 clean room after acclimatisation to ensure absolute precision during assembly. Electrical Discharge Machining Hydro Erosive Grinding Injector assembly To ensure it can reliably maintain tolerances At its Deggendorf site, Liebherr has many The injectors assembled in the clean room of a few µm, Liebherr uses the electrical years of experience with hydro erosive grind- are subjected to various tests as early as discharge machining process based on spark ing. It is used primarily to round injector nozzle during assembly, for checking fitted O-rings erosion in the production of injector holes and exactly set the flow rate. for example. components. Common Rail Systems by Liebherr 9 Comprehensive quality assurance Uncompromising quality assurance is indispensable for as the production creation process and covers the entire the high reliability and availability of fuel injection systems. product life cycle. Efficient