The crankcase, cylinder and cylinder head are unchanged from the previous generation engine, having managed to create a competitive base engine. For the 2017 season, thermodynamic and electronic developments came to the fore.
Among the shortcomings of the EVO4 engine, the absence of a generator played a significant role, which in the case of the EVO5 engine was eliminated by appropriate conversion of the crank mechanism and the control deck. Before designing the fifth-generation engine, the decision was made that the team would not design a completely new concept, but that the fourth-generation powerplant would be reworked. This determination played a decisive role in the selection of a marketable generator suitable for the purpose, as the number of power generation units that can be placed in the engine was thus significantly reduced. With different generators, different ideas were born, of which the most obvious was the placement of the three-phase permanent magnet generator of the Kawasaki ZX10R motorcycle produced in 2004-2005 on the crankshaft. According to the basic concept, a flywheel had to be placed on the main shaft, the inner surface of which had magnets, and the winding was fixed in the deck on the control side with a screw connection. These expectations significantly influenced the design of the fifth generation crank mechanism. Compared to the EVO4 crankshaft, the positioning of the encoder profile, which seems small but is essential for the engine’s operation, had to be changed. This year, the goal was to use a type of encoder profile (Bosch) that was wider than in the past, so it only became necessary to place it on one side of the crankshaft. During the design of the crank mechanism, the biggest challenge was the tight space and the proper fixing of the flywheel. In accordance with the purpose, a flywheel support component was designed, which transfers the torque to the flywheel through matched pins. The torque transmission between the support and the main shaft is ensured by a conical joint, which is fixed with a grooved bearing nut and a locking plate. In terms of mass balance, the crankshaft has been designed in such a way that, with the help of carbide-based (tungsten) rods, the crank mechanism can be used separately with two types of connecting rods (the titanium connecting rod of our own design and the serial production KTM connecting rod).
EVO5 crank mechanism
Formula Student regulations require a 20mm diameter restrictor to be placed in the intake system between the throttle valve and the engine, through which all air drawn in by the engine must pass. The function of the restrictor is to create a pressure drop in the intake system, which considerably worsens the engine charge exchange process. The purpose of the intake system designed for the EVO5 was to minimize this effect and to find the optimal design between the available power and keeping the gas reaction at an optimal level.
Structure of intake system
Several software were available during the design process thanks to SZEngine’s support contracts. An example of this is PTC’s Creo 3.0 Parametric module, in which the intake system is modeled and virtually placed in the car. In order to plan efficiently and quickly, the effect of the changes on the entire system must be known, so it is essential to run simulations. The process of changing the charge of the engine, as well as the effect of the new intake system on the change of charge, was investigated with the help of one-dimensional simulation. The BOOST module of the AVL software was used for this purpose. Finally, in order to analyze the flow in more detail, the intake system was examined on a three-dimensional flow science software. The CCM+ module of the STAR software was available for these studies. The part was further examined with the help of CFD simulations in order to find possible detachments.
The intake systems intended for brake pads and competition were manufactured using different production technologies. A plastic 3D printed suction system was made for the brake pad by Varinex.
3D printed suction system
However, laminated intake systems were prepared for competitions together with the Arrabona Racing Team. The carrying capacity of which is extremely high compared to its weight. The picture shows the final intake system installed in ART04.
Laminated intake system in the car
Previously, the team used a factory Akrapovic exhaust drum, which could no longer meet the required decibel level according to the new sound pressure measurement regulations. We have developed a new exhaust system for our EVO5 engine, which has the same absorption design as in previous years, but thanks to its greater length and diameter, it comes into contact with the exhaust gas over a much larger surface area, and therefore has better sound absorption properties. We checked the concept with in-car measurements, during which we used the same method used in competitions. In terms of placement in the car, we divided the drum in two, so we could use the length obtained based on the measurements. Bodis exhaust helped in the production of the exhaust.
Our EVO5 engine has undergone major changes compared to the EVO4, especially from an electronic point of view. The DTA engine controller used last season was replaced and Bosch MS4 was used instead. This controller is capable of performing much more complex tasks and plays a major role in the fine-tuning of the engine. Hopefully, with its help, we will be able to optimize the fuel consumption and performance of our engine. In addition to these, this controller is much lighter than the previous one, and the consumption of electricity is considerably less. The motor’s sensors have also changed, the types have been matched to the controller, and the aim was to use the lightest possible sensors. Another big change was made to the engine, namely a generator was placed, which was meant to serve the needs of the racing car’s electricity, as well as charging the battery. The maximum power of the generator is 500W, which fully meets the needs of these racing cars.