Testing must remain central to automotive developmentBringing new concepts to market and developing new technologies, such as electrical vehicles, demands a consistent approach to data acquisition and analysis, believes Paul Beardsworth, sales manager UK and Ireland for HBM.
The automotive industry has always been driven by a strong competitive ethos and the need to develop new concepts that capture public imagination and meet the vast and varied needs of their customers. That need is as strong as ever as the decline of oil stocks leads to increased investment in other technologies as the prime mover.
The development of automotive technology starts on the test bench, and leading organisations continue to ensure that remains the case. The BMW Group, for example, recently fitted new test benches to implement more efficient test programs and extend its technological lead. The test benches utilise a pallet assembly to secure test specimens that can easily be docked and appropriate transducers fitted.
BMW required a modular, TEDS-compatible system with twice as many channels and fast data acquisition (DAQ). It selected HBM's QuantumX DAQ system for shorter setup and optimised testing. For example, BMW relies on HBM's torque transducers so that crankshaft-angle-related measurements up to 100kHz can be rapidly saved to a data logger during operation using an EtherCAT bus for parallel and real-time data transmission.
Every aspect of a new design, including individual components and sub-structures, needs to be thoroughly tested to ensure functional effectiveness. The Mercedes Benz SLS AMG, for example, was the first vehicle to be independently developed by Mercedes-AMG. Customers have high expectations when the peak performance of 420kW in a 6.3-litre engine accelerates the car from standing to 62mph in just 3.8 seconds. The model features a steering coupling and crash absorbers independently developed by DURA Automotive Systems Reiche that demanded very high standards during production and quality control. These feature corrugated tubes in which the diameter periodically changes to absorb energy through defined deformation in a frontal collision protecting the driver.
Modern measurement technology, in the form of HBM's MP85A process controller, is used to monitor the press-fit procedure. This records the force and displacement during the press-fit process. All values are recorded and monitored by a PC controlling the test bench.
While these developments remain important, it is the development and testing of hybrid and electrical vehicles that are increasingly the focus. Research into electric vehicles is constantly gaining momentum as fuel prices continue to increase dramatically and environmental awareness becomes more important. However, the efficiency of electrical-drive vehicles - currently around 50% - must be improved. This poses a number of challenges since the standard method of measuring the efficiency of electric motors is to utilize a power analyser on the motor input and torque transducers on the motor output.
The energy loss - and hence the efficiency - is determined by the difference between the electrical power input and the resulting mechanical power output. For most cases this is adequate but vehicle design engineers would benefit from being able to examine and analyse the underlying information. Important knowledge about developing greater efficiency can be gained during research by investigating the raw data.
A secondary problem is that power analysers and other measurement devices used generally need to be laboriously synchronised before testing takes place. This frequently leads to measurement errors while highly dynamic power measurements with more than 50 measurements per second are technically difficult.
There is a lot going on when a vehicle accelerates smoothly and rapidly to 60mph and this demands looking at far more data than is conventionally required. HBM believes that customers should be the master of their data so they can validate their own results. HBM recommends a combination of its Genesis HighSpeed DAQ system and T12 torque transducer. This enables data to be captured and stored for subsequent analysis. Using the Genesis HighSpeed GEN2i model ensures that capturing data at up to two million measurements per second per channel are easily achieved on continuous tests of up to an hour in duration. This in-depth approach complements the use of power analysers to gain an overview.
HBM has also launched a new six-channel board for the GEN2i enhancing its capabilities. The board has an input range of ±20 mV to ±1000V and a sample rate of 2MS/s at 18-bit resolution. The board connects directly to a 20mV shunt as well as to high voltage signals making high voltage probes and oscilloscopes defunct while giving test engineers increased accuracy of 0.1%. Another advantage of this approach is that HBM's Perception software can be used off line to analyse the signal properly and identify additional factors that may need to be considered when searching for greater efficiency.
For manufacturers the message is clear. Proper testing of new designs and technologies is invaluable in the quest to remain competitive.
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