− Our results show up to a five percent energy efficiency enhancement of internal combustion engines and, in turn, up to 5 percent reduction in carbon dioxide emissions on each internal combustion engine and if our recommendations were applied on a global scale, it could have very positive effects on the environment, says Aleks Vrcek, PhD student at Luleå University of Technology.
Resulted in lower friction
Aleks Vrcek and doctoral student colleague Tobias Hultqvist have studied the possibilities for improved energy efficiency of internal combustion engines as part of their dissertation work. In the study, which is a collaboration with Volvo Cars, they have looked at the possibilities of saving energy by replacing conventional plain bearings in crankshafts with more flexible roller bearings on a large scale.
− Today, most use plain bearings for the crankshaft in their engines, a technology with relatively poor energy efficiency due to the surfaces sliding relative to each other, which creates a lot of friction. We have therefore replaced these with roller bearings and optimized the contacts for best results. This has resulted in lower friction and thereby higher energy efficiency, says Tobias Hultqvist.
To achieve the desired result, however, it is required that all parts of the process are evaluated, analyzed and tested.
− Factors such as lubricant, surface finish, the material and heat treatments from which the rolling surfaces are made play a major role. If you change one, you must also correct the other. We have therefore done a lot of simulations and experiments to arrive at the recommendations we have now given to Volvo Cars, says Aleks Vrcek and notes that even if the industry goes towards fully electric cars, large parts of the world’s vehicles will continue to be powered by internal combustion engines under the foreseeable future.
− The global transport sector largely uses vehicles with internal combustion engines and it will take years before electric cars are fully functional on a large scale. The hope is that our research can be part of a green transition, not least by optimizing the engines in hybrid cars as a step in the right direction.
Can be applied widely
The research that Aleks and Tobias engaged in in the project revolves around crankshafts in passenger car engines, but the knowledge of how materials, lubricants, surface finish and friction interact can also be used in other applications.
− This technology can be applied very widely, for example in gearboxes for both hybrid cars and electric cars. All machinery that uses similar technology can benefit from our research, says Tobias Hultqvist. He sees the study as a small piece in the major adjustment required in the industry.
− If we get more energy-efficient mechanical systems, it will also facilitate the use of renewable forms of energy in the future. The optimization of reliable roller bearings in the machinery also improves the reliability and efficiency of the engines and then we do not need to produce as much material for broken and worn engines.
Tomas Johannesson is group manager at Volvo Cars and industrial supervisor of the project. He sees great gains with the increased knowledge base that the research provides.
− Our goal is to manufacture the best products, which means that every small part needs to be used to the maximum, no compromises are allowed. In order to be able to deliver the best products over time, we need to work to increase our knowledge base. Aleks and Tobias' research contributes to better-dimensioned tribological systems in general and rolling element bearings in the motor environment in particular. Parts of the results have already been used in our analyzes of future products.
That Volvo Cars chooses to collaborate with the university is due to the research group's recognized high competence in the field.
− Luleå University of Technology fits like a glove in this particular project. Their classic machine element philosophy with experimentally supported theory and theoretically supported experiments where you look for the biggest influencing factors means that you can quickly move forward on unbroken ground. With regard to tribology, it is generally known that Luleå University of Technology has an internationally renowned reputation.