The ball bearing motor mystery 2022
Contents
Project team
Honours students
- Xinyao Feng
Supervisors
General project description
The ball bearing motor is a mystery because to this day as no engineer knows how it works! No one understands the physical principle at all. Your job is to do some experiments to investigate this motor and why it is that it rotates. Understanding the principle is important. It may not be useful for large motors, but it may be interesting for micromotors and micropumps that have numerous applications.
Abstract
The mystery of the ball-bearing motor is based on the Huber effect, a theory named in memory of J. Huber [1]. There’s been no conclusive experimental evidence to support this effect since then. In 1959, J. Huber found additional rotational force on the conductive wheel pair when the current was supplied and pass through the track [1]. Whether direct current (DC) or alternating current (AC) is used, additional forces that accelerate the wheels can be observed. Milroy first described the ball bearing motor based on the Huber effect [2]. It is composed of a metal shaft with one ball bearing is installed at both ends, as shown in Figure 1.1 [3]. Give an initial beginning torque to the shaft when AC or DC power is applied to the system, and the system will continue to rotate in the starting direction. The motor can rotate in any direction freely.
Aim
According to previous research, many theories have been put forward, but no conclusive experimental evidence exists. Therefore, this project aims to study the physical mechanism behind the ball-bearing motor. This project will build physical models using relatively small size ball bearings. The small sizing can reduce the working current. Then, distilled water will be applied to the system to reduce the overheating and self-destruction effect. In addition, the liquid metal will be used in a modified system to reduce the system friction force. The Arduino board, LCD scream, speed encoder module and load cell will be used to collect data, which will be used to establish the relationship between angular velocity and torque. Meanwhile, simulation experiments using the software COMSOL will be performed in parallel with the physical experiments. It is used to perform the experiment in ideal cases and support the physical experiment results through software calculations.
Background
None of the existing hypotheses about the physical mechanism behind the Huber effect can contradict other hypotheses or summarize conclusions. Three representative assumptions are the electromagnetic effect, thermal expansion, and plasma discharge.
Electromagnetic effect
Grunberg initially hypothesized that the Milroy motor phenomena were caused by an electromagnetic effect. [3]. Each ball in the bearing has the properties of magnetic field B0 and volume current density J0. Because current passes between the contacts on the inner and outer rings, it is assumed that the ball’s angular velocity is ω. The primary magnetic field B0 will be generated, and the secondary volume current density J1 will be generated according to the movement of B0. The process repeats as the ball rotates, which leads to the redistribution of associated magnetic field B1 and electric field E1 and charge. The primary torque source results from the interaction between B1, J0 and B0, J1. Grunberg’s research shows that torque and vector ω. The direction is consistent, so the motor will produce rotating torque only when running, and there is no starting torque. At the same time, he proposed that the speed is directly proportional to the current square based on the analysis of static Maxwell equations. T = k * ω* I2 (1) where I = sqrt (a + b * ω)(2)
