The Formula Student E-Stall team improves the performance of its electric race car with 3D-printed heat exchangers

3D printed cooling jacket

E-Stall Racing Team from Esslingen University of Applied Sciences designs and builds an electric race car to compete in the Formula Student competition.

If you are not familiar with formula racing for students, be aware that in each competition, a team of students must build a formula race car with a single seat, with which they compete with other teams around the world. The competition is won not only by the team whose car is the fastest, but rather by the team that exhibits the best combination of design, performance and financial and business planning.

Formula Student challenges team members to go the extra mile in their training by incorporating intensive design and manufacturing experience as well as considering the automotive industry’s finances. The teams assume they are a developer developing a prototype that will be evaluated for production. The target group is the non-professional weekend runner. The race car must have really good driving characteristics such as acceleration, braking and driving characteristics. It must be offered at a very reasonable price and be reliable and secure. The car’s market value also increases through other factors such as aesthetics, comfort and the use of standard components that are readily available for purchase.

The challenge facing teams is to put together a complete package that includes a well-built race car and a sales plan that best meets these criteria. The decision is made by a jury composed of experts from motorsport, the automotive industry and suppliers. The judging panel will evaluate each team’s car and sales plan based on construction, cost planning and sales presentation. The rest of the assessment will take place on the track, where the students in a series of performance tests will demonstrate how their self-built race cars perform in their real environment.

The engineering perspective …

For many years, E.Stall is an integral part of Formula 1 and has proven itself as a competitor. Based on the results from recent racing seasons, they have wanted to improve the cooling system of their electric race car in terms of reliability. The former cooling jacket used by the E.Stall team was made of a temperature-resistant polymer, which was mounted directly around the electric drive, consisting of two shells. The purpose of the cooling jacket is to regulate the engine temperature and prevent overheating. Without adequate cooling, the risk of engine damage is quite high. During the season of using the Polymer Cooling Jacket, a two-component solution has been shown to be prone to leaks and hence problems.

In a four-wheel drive electric race car, the high-performance electric motors must be cooled. Since these motors have a high power density of 10kW / kg, they would overheat under full load without cooling. There are two cooling circuits, one on each side. The four motors are cooled, as well as the corresponding inverters. Using EPlus3D’s expertise in additive manufacturing design and its entirety Latest Metal Powder Bed Fusion Solution EP-M260 Dual-Laserthe cooling component leakage problem could be solved and the performance could be significantly increased.

Invert cooling
Simulation of cooling jacket flow
Heat transfer

Thanks to the versatility of metal 3D printing technology, the E.Stall team was able to test new shapes, which until now had not been possible with traditional methods. At the same time, the entire surface of the cooling jacket can be used for heat dissipation due to the nature of the aluminum material.

The 3D-printed cooling jacket will be an efficient and reliable product. We were able to create complex structures, which is unthinkable in a conventional way. Using EPlus3D and the latest additive manufacturing technologies, we were able to reduce the wall thickness thanks to the high precision of the 3D printer and therefore reduce the overall size of the parts.. »

In addition to the cooling jacket, EPlus3D helped E-Stall with one heat sink for its inverters and a control component. Both have also inherited the multi-component functional integration, lightweight design and improved overall performance.

Thanks to the functional integration of the cooling system, plugs and mounting, mounting steps are saved and the fail-safe design is no longer exposed to leaks. The minimal wall thickness of the part helps to reduce the overall diameter and therefore creates more space for the other suspension components that are based around the electric motor.

The high quality of the prints is crucial to their function. A close-fitting, deep-drawn cooling jacket was just as important as the straightness of the cooling plate to the inverters. Both performed well and kept the motors and inverters below 65 ° C, which the team says is an “incredibly good result.” Compared to the previous season, when the engines regularly reached 120 ° C, the advantage of the manufacturing process of EPlus3D, which enables the integration of the design, is clearly demonstrated.

The design of the cooling jacket made it possible to simulate a cooling capacity of 3.8 kW. Due to the low temperature of the components, they can work more efficiently, which helps to increase the car’s range and improve acceleration.

Thanks to the excellent construction of the components and all the parts, as well as the dedication of the entire E-stall team, they achieved a 4th place in the technical design competitions of FS Czech and FS Alpe Adria. According to Felix WenzelburgerProject Manager Powertrain & Vehicle Dynamics, “this discipline is the most important of all the static disciplines and assesses the team’s technical knowledge and the processes they use to design the car.. »

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