Last year our team decided to develop unique telemetry system for the ECU, Bosch MS4. The development process of the system followed our idea and had very low development cost. In the first generation we managed to transfer wireless the data of engine speed, ignition, injection, battery voltage, temperature and pressure data). More functions can be implemented with the help of the hardware, because it contains more circuit units, so in the future we would like to expand the software capabilities of the telemetry system. On the figure the operation can be seen:
The system has two separate units: Telemetry circuit (transmitter) and Bridge (transceiver). The transmitter communicates with the ECU through CAN bus, and saves the engine parameters from the datastream. Then orders them into packages and transmits to the transceiver. The radio transfer process is now one-way. The transceiver sends the gotten data to ethernet network, so it can be reached on all nodes. Now our team develops a software to log and display data in real time.
Based on pre – measurements the range can reach 1000 metres on open ground.
The most important part of the cooling circuit is the water pump, which is a Davies Craig EWP 80 type electronics model. Because of this solution the pump gets the performance from the battery, not the crankshaft. For optimizing the cooling, the electronical control unit drives the pump after the engine condition. The cooling radiator is self – designed, cooling surface is 200×300 mm, thickness is 40 mm.
The oil circuit of EVO 2 is same to EVO 1, it is dry – sump. We used the oil tank of EVO 1, but instead of stock oil pump, we mount a self – designed, 4 stage pump. In case of EVO 1 there was a problem with oil foaming due to the failure of oil system. The custom designed oil pump prevents the oil foaming, and has a larger sumping capacity ratio than stock ones, so it prevents gathering of oil in the crankcase. The oil pump has one pressure way, which drives the oil to the crankshaft, the drive and the piston cooling nozzles. The task of the other 3 sections is to evacuate the oil from the rotating space and the covers
The goals was laid early at the development process of EVO 2. These were mass reduction, easier assemble process, compactness and cost efficiency. The geometry was changed, the most significant difference is the placing ribs at bearing spaces. This solution is a result of FEM and topology analysis. We have reached 30 % of mass reduction.
We tried to use different materials in case of EVO 2. The side cover was changed to fiber reinforced plastic instead of metal. The density of this material is smaller than aluminium, so high mass reduction could be reached. The strength of polyamid is smaller than aluminium, but it was not subjected to load.
There were many of small changes to develop assemble process, safety and the efficiency of lubrication system. We looked after the cost efficiency and manufacturing challenges during the design process of the new crankcase, so many consultations were carried on. To summarise, the EVO 2 engine is more compact, lighter and the assemble process is easier than EVO 1, which are very important things in Formula Student.
In case of EVO 2, we kept the dealt, 3 part crankshaft design. The most important task was to further reduce the rotating masses. The most effective result was in case of crankpin. On the counterweights conical geometry was designed to reduce ventilating losses and because of assemble and strength process 2 ’ears’ were mounted on both sides. To mass equalization we used wolfram pins, but on both sides there are 1 bigger and 4 smaller pins instead of 3 same pins. Bearings are stock cylindrical roller bearings. We used different simulation softwares to determine loads, such as AVL Excite Designer and AVL Power Unit, with the help of our sponsors. The main advantages of the EVO 2 crankshaft are mass, stress and size reduction.
The air intake system of EVO 2 is 50 % lighter than EVO 1, and serves the charge exchange process more efficiently. On the beginning of the system there is an AT Power – developed for Formula Student – inlet throat, which includes a 19/20 mm restrictor and the throttle valve as well. The next part is the airbox, which is optimized for the engine, the volume is 3,5 litres, which is half of the EVO 1. Most of the mass reduction can be reached with the repairing of this part.
The intake pipe is also made of carbon instead of Aluminium, so we could reach huge mass reduction. We tried to gain advantage comes from gas dynamic processes, so several simulations were run in AVL Boost software. The most important task of injector mount is the optimal injection. The exhaust system is also light and we tried to use the positive effects of gas flowing. We use electronic AC pump to get fuel into the engine, with pressure limiter fuelbridge.