Suspension dampers in an autonomous racing car

• What was needed: dryspin® high helix lead screw in left-hand thread and stainless steel with matching dryspin® injection moulded threaded nut
• Requirements: Small installation space, high load, high efficiency, 100 % lubrication and maintenance-free, low weight
• Industry: Automotive industry
• Success for the customer: By using the lubrication-free dryspin® lead screw technology, High-Octane was able to save €1,093 in costs and reduce the consumption of lubricant and hydraulic oil CO2 by 1.1 kg

As part of the Formula Student program, the team developed an active damper for the chassis. Formula Student is an international student design competition in which university teams compete against each other in various disciplines, creating and producing their own racing car every year. The chassis is of particular relevance as it is the interface between the vehicle and the tarmac. The targeted adjustment of the spring/damper units to transfer power from the ground via the tyres to the chassis is essential for a successful race. The system converts the linear movement originating from the vertical wheel movements into a rotary one. Based on a BLDC electric motor as a damper, it is possible to actively influence the driving characteristics (e.g. rolling and pitching behaviour) of the autonomous electric racing car while driving. Due to the given regulations of the "Formula Student Germany", ±25mm spring length of the wheel assemblies must be maintained. As lightweight and aerodynamics are two important goals of the team, it was also necessary to find the lightest and smallest possible solution (1.2kg incl. steel springs per unit) so as to install these in the carbon monocoque. The high forces acting on the racing car and the damper while driving also play an important role.

To accomplish this task, a dryspin® high helix lead screw was used in combination with an injection moulded threaded nut. These components were specially designed for a small installation space with a diameter of less than 11 mm. The selection of a suitable pitch of 25 mm also played a decisive role. A particular challenge was to avoid jamming due to insufficient pitches, while at the same time taking into account the required transmission ratio. Despite a high load of around 4.2 kN, this poses no problem for the dryspin® screw drive. The high efficiency of the dryspin® screw proved to be advantageous as it leads to improved damping efficiency and reduces energy loss in the system. This enables more efficient control by the damping motor.

By using this solution, it is easily possible to influence the aerodynamic position of the vehicle, for example to optimise drag and thus significantly reduce fuel consumption. What is particularly remarkable is that this solution was developed entirely independently by the student organisation. This makes it a unique innovation in the world of Formula Student.