Engine And Powertrain Testing
Indian Automotive industry is leapfrogging to BS 6 regime with little time to put pieces in place. This has created a big challenge in engine testing domain and a technical void which needs to be filled in less than a year's time i.e. by April 2020. Most of the OEMs are ready with concepts, technologies and after treatment options. But time available for engine testing still remains very short.
Even though the engine testing methodology remains the same for most of the powertrain with the exception of after treatment options, there are new challenges for engineering aspects of BS 6 implementation.
1- Engine and part development - This is the core area of development where most technologies are already existing. Most of the OEMs are entering engine testing and powertrain calibration phase.
2- Design and Packaging requirement- To understand the impact of BS 6 emission norms on designer, lets understand the problem from vehicle integration point of view. After treatment systems are needed to be fitted in existing models and this creates challenge in packaging. Each OEM today has multiple models, take an example of Maruti which has to convert more than 15 models and make them ready by 2020. Similarly, commercial industry leaders like Tata Motors and Ashok Leyland too have multiple models to make ready.
3- Engine testing and validation for vehicle performance and durability - Most of the OEMs are in prototype phase and will be entering this (engine testing & validation) phase in 2019.
- Since many models of every OEM need to be validated, it has created a shortage of time and resources. Thus, OEMs are working round the clock to achieve efficient engine testing.
- Second challenge is huge amount of data that is been created during this engine testing in short time period. This we have answered using the BS 6 Edition of ASI Datalab. Click here.
Following diagram shows the major areas that need to be studied for BS 6 implementation
Most OEMs are now ready with proto vehicles. Now biggest challenge is now performing engine testing in the Indian climate with hot temperatures of up to 50-degree Celsius, cold temperatures of -20 degree Celsius and the coastal regions.
Components/Parameters to be studied for Powertrain testing
1. ECU remapping
Stringent BS 6 requirements need to be validated both at component level as well as vehicle level. Once System is fitted in the vehicle, ECU maps the data from various sensors and checks vehicle for emission. This data is logged for various load cycles to validate vehicle emission performance and check compliance. Challenge here is to cover mileage and optimize the ECU settings to come to the best suited calibration value for the field requirement. ECU also provides other sensor data which helps in understanding vehicle behavior during test runs. This study is used to map various engine parameters like- engine load, fuel consumption, engine torque, engine rpm, gearbox torque, thermal characteristics, Emissions level.
Some of the general outcomes of this study are in below graphs which are used to assess vehicle performance based on ECU remapping.
Graph 1- Various ECU mapped parameters in usage run.
Graph 2- Engine Torque vs RPM graph
2. Duty Cycle Mapping
Since vehicle is used in different climates, this type of testing is done to understand engine performance. Inlet, outlet pressure and temperature are mapped with turbocharger performance and engine performance de-rate is evaluated. You can refer below example data graph for Duty cycle.
3. Engine and Powertrain Noise testing
Powertrain components are one of the highest contributors of noise in a vehicle. Noise is created by-
b. Turbocharger- rev noise, blade passing frequency noise - compressor side and turbine side.
c. Gearbox, axle, timing gear assembly- Gear meshing noise, timing assembly, gear chattering, gear whining noise, resonance, torsional vibrations, etc.
d. Sound quality of powertrain is very critical and is studied for tonality, boom, loudness, etc.
Tools like near source noise measurement, in-cabin noise measurement and modal analysis are used to understand the noise characteristic and its impact on passenger as well as passer-by.
4. Engine and Powertrain mounts
Mounts play a critical role in understanding the vibration transfer to vehicle body. Mounts are studied for transmissibility and their critical frequencies.
Following is a transmissibility curve for engine mount –
5. Torsional Vibration Analysis
Powertrain components are highly prone to vibration. Complete powertrain experiences linear vibration and torsional vibration. Torsional Vibration analysis of automotive powertrain is very important to reduce the fatigue load on casing/components and to reduce vibration and noise originating from powertrain components. Powertrain testing procedures and methods used to assess torsional vibration are mentioned here (Torsional Vibration blog) Components specially checked for this are- Engine, clutch and gearbox.
Below graph gives an example of torsional vibration resonance-
Powertrain is studied for its durability using real life cycle runs for actual vehicle as well as rig testing. In this test various parameters of powertrain are mapped with overall vehicle like- oil condition, oil usage, engine performance degradation, wear of clutch, gear box issues, etc.
Powertrain forms a critical input for driver and passenger experience as based on this it is studied how vehicle will respond to different city and highway driving requirements. For this various gears are used
These are some of the examples of parameters that are generally used. We have tried to summarise main areas of engine and powertrain testing for vehicle validation point of view.