Electric motors are becoming increasingly important—they are not only the heart of electric cars, which now account for around 20 per cent of new vehicle registrations in Germany, but also of electric two-wheelers, ships, and aircraft. For electric motors to work well, they must be built with great precision. A narrow air gap between the rotor and stator plays a crucial role here, i.e., between the moving component that rotates (rotor) and the fixed part with a magnetic field that drives the motor (stator).
The air gap has a significant influence on the efficiency and service life of the motor. If this air gap is inhomogeneous—i.e., uneven—the motor will not run smoothly, its efficiency will suffer, and it will break down more quickly.
Air gap important for quality assurance
For this reason, the air gap of the motor must be measured for quality assurance purposes. Automating this air gap measurement is the goal of the new “MotorInspector” research project by IPH – Institute for Integrated Production Hannover and MFP Messtechnik & Fertigungstechnologie. IPH and MFP are conducting joint research into automated quality control over a period of two years. The research project is funded by the European Regional Development Fund (ERDF) and the state of Lower Saxony.
This topic is particularly exciting for the relatively new axial flow motors, also known as “disc motors.” A homogeneous air gap is particularly important for these motors, as even the smallest deviations can significantly shorten their service life.
In the project, IPH is responsible for the automation concept and MFP for the air gap measurement itself. The basis for this is a sensor developed by MFP. The so-called “gapMaster” measures the air gap resistively. A sensor scans the gap directly. According to the project partners, this measurement method is comparatively robust and fast. However, it cannot yet be fully integrated into industrial manufacturing processes.
Developing an automated measuring system
The “MotorInspector” partners therefore want to develop an automated measuring system based on this sensor. This will involve the use of a robot that is able to automatically and precisely insert the sensor into the center of the air gap with the aid of a camera or laser. In this way, IPH and MFP want to enable automated quality control directly in the production process – without the manual intermediate steps that have been common practice up to now.
A prototype of an electric motor is currently being built for “MotorInspector”. Tests will be carried out using it in the course of the research project in order to develop and iterate an automation concept for air gap measurement.
For the project, the participants are currently looking for companies that manufacture electric motors—in particular axial flux motors, but also radial flux motors. Automotive groups and suppliers as well as start-ups and research institutions working in this field can contribute their expertise. The results of the survey will be incorporated into the research project in anonymized form. The contact person is project manager Simon Pauka; his contact details can be found on the project website.
iph-hannover.de
This article was first published by Florian Treiß for Ev Authority’s German edition
