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Magna’s multifunctional roller dynamometer for advanced powertrain and vehicle testing

Introduction

Magna has a multifunctional roller dynamometer suited for vehicle, powertrain and engine testing at its site in St. Valentin. The roller dynamometer is equipped with four individually controlled rollers which enables testing of motorcycles as well as two- and four-wheel-drive vehicles and is suited for the following testing scenarios:

  • Noise, Vibration and harshness (NVH) testing
  • Performance and emission testing

The dyno test cell fulfills free-field requirements for NVH testing and allows for NVH testing of standalone engines. For performance and emission testing the dyno facility is equipped with a constant volume sampling (CVS) system and several exhaust gas analyzers to calibrate and adapt all kind of emission systems for diesel and gasoline engines. All tests on the dyno can be performed in a temperature range between -20 and +50 °C.

Figure 1: Emission, calibration and NVH benchmark

Figure 1: Emission, calibration and NVH benchmark

 

Acoustic testing features

The test cell around the roller dyno is equipped with a reflecting plane as specified in ISO 3745 to provide free-field conditions. The walls and the ceiling are covered with specially designed multi-layer flat surface absorbers while the floor reflects acoustic waves. The valid frequencies for free-field conditions range from 40 Hz to >10 kHz. The lower threshold of 40 Hz represents the 2nd order (engine speed based) for a 4-cylinder engine at 1200 rpm. Low engine speeds are typical for customer cycles, e.g., slow acceleration pattern or typical city driving in higher gears at low speeds.

Measurement equipment typically used for NVH evaluations features precision microphones, three-axial accelerometers, high-resolution speed sensors suited for torsional vibration applications, and torque sensors (mounted on shafts or plates).

Accelerometers are typically placed on mounting or interface points on engines, bodies, or chassis (active/passive side comparison) as well as comfort points like seat rails and steering wheels. Microphones are usually placed inside the car at the height of the driver’s ear or other passenger seats. Due to the acoustic performance of the test cell, measurements outside of the car can be performed at various locations (for example, an exhaust system evaluation or investigations regarding cylinder deactivation).

There are several acoustic testing scenarios that can be conducted on the dyno including:

  • Full vehicle evaluation (Figure 1)
  • Full vehicle with engine inside the vehicle connected to powertrain but mechanically decoupled from the vehicle and fixed to test stand
  • Engine standalone on acoustic engine rig within the dyno test cell (Figure 2)

Figure 2: Acoustic engine test rig (benchmark vehicle)

Figure 2: Acoustic engine test rig (benchmark vehicle)


These exemplary testing scenarios make it possible to segregate the various noise and vibration sources and transmission paths.

Standard load cases that are used for NVH evaluations on the dyno:

  • Full-load (WOT) or part load (POT) acceleration
  • Coasting
  • Slow acceleration ramps
  • Road simulation (real driving load)
  • Customer specific cycles

A typical approach during an NVH project involves a variant study on a component level and validation of the resulting configuration on a vehicle level.

 

Performance and Emission testing features

For performance and emission testing (Figure 3/4) the typical measurement parameters are temperatures, pressures, flow rates, crank angle indication (pressure, injection, etc.), torque (mounted on shafts or plates), and ECU/CAN signals.

Figure 3: Standard clearance for software upgrade (Emission)

Figure 3: Standard clearance for software upgrade (emission)

 

Figure 4: Standard clearance for a software upgrade (emission)

Figure 4: Standard clearance for a software upgrade (emission)

According to the characteristics of standard test cycles the exhaust gas emissions measurement can be split up into four testing phases (bag sample and modal). To analyze different exhaust gas concentrations, four exhaust gas analyzers are available - three for undiluted inline measurement to evaluate exhaust after-treatment systems (e.g., DOC, DPF, NSC, and SCR) and one CVS system for diluted exhaust measurements.

The basic measurement instrumentation is vehicle based (Figure 5), making a combination of chassis tests and on-road testing easy to implement. Misfire detection or OBD calibration, especially for driving under heavy loads, are likely done on a chassis dyno.

 

Figure 5: Measurement Instrumentation Acoustic Engine test rig (benchmark vehicle)

Figure 5: Measurement Instrumentation Engine (benchmark vehicle)


Driving cycles are not simply standard time-based speed driving cycles. Another approach is to use a driving distance slope-based cycle. Typical driving cycles for dyno tests are NEDC, WLTC, FTP75, and ADAC eco, as well as customer-defined cycles.

Depending on the measurement instrumentation in use, the efficiency of single components like wheels, differential, gearbox, engine and measures like cylinder deactivation can be determined (Figure 6).

Figure 6: Emission, Efficiency and Application Benchmark

Figure 6: Emission, efficiency and calibration Benchmark

Supervised by highly qualified employees, Magna’s multifunctional roller dynamometer can perform comprehensive NVH, performance and emission tests using modern measurement equipment.

 

Detailed Specification (PDF)

 

 

 

 

 



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