State-of-the-art methods for stable power and high load capacity
Modern development tools such as the Finite Element Method (FEM) or Computational Fluid Dynamics (CFD) analysis contribute towards the constant optimization of the injection system and its modules.
Many components of a fuel injection system are subjected to cyclic loads. When testing with FEM, particular emphasis is placed on determining and then optimization fatigue resistance.
All components are also inspected intensively by calculation engineers with CFD analyses. Flow effects inside the components are modeled and the findings are incorporated in the design.
All components in Liebherr Common Rail systems are subjected to thorough and comprehensive validation program. This is oriented on excellent system reliability and availability under demanding environmental conditions, as well as towards a long product service life. Accelerated test procedures are used to investigate the ageing process of system and components. Field trials are also a key element of the validation process.
Stable multiple injections
In the case of multiple injections, the pilot injection is crucial for the engine to run silently, the main injection ensures optimal power delivery and maximum torque, and the post-injection reduces emissions.
The 3-way servo valve ensures that the injection spray is established moderately. The injection process ends with very fast closure of the nozzle needle. This results in a very clear boundary for the individual injections and a precisely measured amount of fuel - both of which are decisive factors for an optimal combustion process, low fuel consumption and minimal raw emissions.
Minimal control leakage
Liebherr injectors are set apart by their very small amount of control leakage. In the case of system injectors for engines with a capacity of up to 2.7 liters per cylinder, at full load it is a maximum of 15 ml/min. This provides the following advantages:
- higher degree of efficiency and therefore lower fuel consumption
- lower leakage temperatures, therefore less cooling requirements
- good tolerance of various fuel qualities
Injection timing control function
With the help of the injection timing control (ITC) function, even small quantities of fuel can be dosed more precisely. Each injector has the necessary hardware to determine the start and end of injection. Additional information gained from the start and end of the injection provides relevant condition monitoring data and the software regulates the amount of fuel to be delivered individually for each subsequent injection. This compensates for drift and keeps the injection quantity from the injector constant over the entire service life. The software-controlled Injection Timing Control (ITC) function works without an additional connector interface.
Liebherr uses an up-to-date computer-assisted quality management system that is implemented as early as the production process and covers the entire product life cycle. Efficient test benches, often specially developed for Liebherr, are used in testing the high precision components.
Extensive entry inspections
All purchased parts of the Common Rail fuel injection system are checked for their highest quality with the aid of highly modern measurement instruments.
These include for example, 3D coordinate measuring devices roughness and contour measuring systems as well as an optical surface scanner.
Before delivering the fuel injection systems, the high-pressure pumps, injectors and high pressure connectors are tested 100% for functional and service life-relevant quality features such as flow, torque or leakage. The Data Matrix Code (DMC) is used to track the assembled parts and assign them to the corresponding system components.
Measurements and testing for injection systems
Leakage test of the injector
A camera system is used to test the nozzle or nozzle needle to ensure that there is no leakage. In the process, the camera records any drop formation on the nozzle which is subjected to high pressure.
Spray pattern test bench
With the aid of a camera, the test bench measures the geometry of the spray pattern of the injector. Due to the very high speed of the injection process this places high demands on the measurement system as well as on the synchronization of the measurement and control loop.
Modern measurement instruments are used to measure the geometry of the Liebherr Common Rail system parts. The photo shows the evaluation of the round surface of the control valve.
Highest quality standards
Quality assurance is certified according to DIN EN ISO 9001:2015 and complies with VDA standards (reliability control circuit). Statistical evaluations and FMEA (Failure Mode and Effects Analyses) are an integral part of the process, as well as the effectiveness testing of changes. In all our processes and operations, we follow the principle of PDCA and integrate Continuous Improvement (CI) in our daily work.