GreenMot Develops Custom Systems for Engine Testing

When GreenMot started its activities in October 2010, it chose neither a “comfortable” market nor a simple path. The market for the testing of engines has a large number of actors with well-established leaders. At the time, this market had experienced several crises, particularly in the automotive sector. And GreenMot didn’t take the easy way in order to break into this market; it decided to start from scratch, without taking over an existing company, and hence having to develop its complete client portfolio. But its founder and president, Stéphane Londos, has vast experience and he chose an approach that would quickly enable the company to hold its own: he focused on precision tests, and if the necessary sensor did not exist, he developed a custom sensor in order to adapt it to the structure to be tested, and not vice versa.

That is how GreenMot uses its in-situ sensor directly integrated into the engine to measure the torque of the tested engine. This sensor has been specifically developed in order to be adapted to the mechanical and environmental stress of the engine. HBM is at the heart of this strategy. As a technological partner from the very beginning, HBM supplies the complete instrumentation chain, for the majority of GreenMot’s applications. Both companies benefit from this privileged partnership: GreenMot is able to distinguish itself from its competitors while HBM consolidates its know-how in engine applications and uses its experience and knowledge to develop new products. 

Problem

GreenMot started from scratch as a new company in the market for the testing of engines in 2010. This market has a large number of actors with well-established leaders and – at the time – had experienced several crises. Without taking over an existing company, GreenMot had to develop its complete client portfolio.

Solution

GreenMot focused on precision tests, and if the necessary sensor did not exist, developed a custom sensor for measuring the torque of the engine to be tested in order to adapt it to the structure to be tested, and not vice versa. As a GreenMot partner from the very beginning, HBM supplies the complete instrumentation chain for the majority of the applications.

Result

With a focus on precision and repeatability, GreenMot helps its customers to further improve the performance of their products. The benefits to be gained are sometimes marginal – but still essential in a very competitive environment. Thanks to this strategy, GreenMot has enjoyed rapid growth.

Tests in all forms

GreenMot’s strategy paid off, the company is growing rapidly. Today, 8 years after the company’s foundation, 37 engineers and technicians are working together to offer customized solutions to their clients. Over the years, the company has gradually expanded its geographic coverage and now export to Germany, Italy, Austria and Switzerland (and indirectly everywhere in the world). Due to the space limitations of its original facilities, the company moved into a 3500 m2 premises in Villefranche-sur-Saône, close to Lyon, in 2014. This geographic positioning also distinguishes GreenMot from its competitors most of which are located around Paris.

GreenMot’s mission hasn’t changed since the beginning: testing of propulsion systems (thermal and electrical) and energy systems, in particular for automotive, heavy-duty vehicles, railways and industrial equipment (cooling systems, power generation systems, etc.). Over the years, this strategy has been proved correct, extending the boundaries and powers of the analyzed equipment. That is why GreenMot has acquired a high-power testing cell for applications far beyond the automotive sector (military vehicles, bus, heavy goods vehicles, agricultural equipment, construction machinery, etc.).

“This test equipment is unique in Europe,”

comments Sébastien Ferragne, an engineer specialized in test engineering, sensors, instrumentation and methodology, as it combines climatic test equipment (from -46°C to +55°C) and high-power mechanical equipment (600 kW). 

Example of a custom-developed torque sensor. This has been physically modified for integration into the engine output shaft. It is equipped with strain gauges developed and attached by HBM.

The company’s strategy has evolved accordingly over the years. That is why there are now two distinct fields of activity: testing based on the clients’ specifications on the one hand, and the construction of testing equipment on the other.GreenMot offers turnkey tests for its testing operations. This approach starts with the specification of the sensors, followed by the planning of the test campaign and post-treatment according to the client’s needs. Test duration can range from one day to several months, starting from the validation of the conditioning, adjustment of the pollutant system, through the complete vehicle benchmark analysis. Tests are generally performed at GreenMot facilities, but in some cases, they can be provided on the client’s site.

The second field of activity involves the development and supply of testing machines and allows GreenMot to use its experience gained in the first field to offer testing machines of a higher quality. These machines are specifically developed based on customer specifications, the R&D department works directly with them. The common denominator of these two activities remains the specific measurement, but the convergence goes much further, says Sébastien Ferragne: “There are very strong synergies between these two activities. Testing operations help us design new testing equipment, just as the development of testing machines helps us to carry out the tests. These synergies give us high dynamics and enable us to create an added value compared with our major competitors who do not have this double activity of testing and testing machines production.”

Research into precision

The majority of GreenMot’s clients operate in a very competitive environment. If they want to improve their products’ performance, the expected benefits are marginal – yet essential. GreenMot supports them in this quest.

“We focus on precision tests, and one of our great strengths is the repeatability of our tests. When we measure consumption, for example, we can achieve a 0.1% accuracy, putting us ahead of our competitors and allowing us to distinguish between very small-amplitude phenomena. Starting from there, it is possible to redefine tests, or to use new types of test in order to investigate potential areas of improvement,”

continues Sébastien Ferragne. To achieve this, GreenMot has developed a robot driver.

Beyond the control and command, there is the complete measurement equipment that is essential here and elsewhere. The classic method of measuring the torque generated by a vehicle is to use roller dynamometers and to measure the torque at the rollers driven by the vehicle’s wheels. This is an indirect measurement method, however, with intermediate elements that impair precision and repeatability. In order to improve measurement accuracy, GreenMot measures directly the torque at the wheels using HBM torque transducers. To go even further, GreenMot offers to use specific torque transducers directly at the engine output shaft in the vehicle. It also has to have sensors capable of being integrated into this environment. In order to overcome the mechanical stresses (dimensional and environmental), the company uses custom torque transducers developed in partnership with HBM. In the beginning, HBM had been chosen for its capability for carrying out precision measurements and developing special sensors. Representing only a small business volume at that time, GreenMot was surprised by the interest shown by the German engineering company. This immediately created a climate of trust, and the relations have not ceased to deepen during the course of the developments.

To define these sensors, GreenMot draws on its own competencies in mechanical engineering used for designing its test benches. The engineers use the CAD models of the vehicles to be tested (these models are either provided by the manufacturer or are created by digitization of parts by a partner). The actual sensors consist of a sensor body on which HBM strain gauges and the transmitter for the measured values are mounted. The development methodology for these torque transducers follows the classic V model with all the project definition steps on the downward line of the V and different manufacturing and validation steps on the upward line of the V. Process development can take between 18 and 20 weeks. Here HBM provides its know-how in the field of sensors, in particular regarding the positioning of the strain gauges, and ensures their adhesion to the test body and the use of the associated process to guarantee the quality of the results. Classic strain gauges are used, but within the context of these co-developments with GreenMot, specific geometries or temperature compensations had to be evolved. Precisions obtained are better than 0.1% in the laboratory and 0.2% in real environments. The measurement frequency is 1 kHz.

V-model development of a custom torque sensor. While GreenMot concentrates its know-how on the test body, HBM focuses its know-how on the positioning of the gauges and their adhesion.

The cooperation is not going to stop

GreenMot uses the standard QuantumX systems from HBM for the actual data acquisition. Since GreenMot is also involved in the development of electric vehicles, the company also acquired Genesis HighSpeed data acquisition systems from HBM. They are capable of analyzing high-frequency voltages and currents (controlled by multi-level pulse width modulation) generated by the control inverters of the electric motors. GreenMot is at the heart of the development of HBM’s eDrive concept, a modern measuring system designed for tests on electric motors and power inverters.

And tomorrow? The cooperation is not going to stop when it’s heading in such a positive direction! Several developments are currently underway to try to win a major order for the measurement of power and torque. Precision, now and always...

About GreenMot

GreenMot is a young French company located near Lyon specializing in the testing of internal combustion engines, propulsion systems, and energy systems, in particular in the field of automotive, heavy goods vehicles, railways, and industrial equipment (cooling systems, power generation systems, etc.).

Do you want to know more about GreenMot’s projects? Please visit their website: www.greenmot.com

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