VE Mechatronic Brake: Development and Investigations of a Simple Electro Mechanical Brake 2010-01-1682
Scientists at the Austrian Institute of Technology (AIT), formerly Austrian Research Center, focused on investigating electro mechanical brakes (EMB) for automobiles. Research showed that EMBs can address brake distribution with regenerative and friction braking ("blending") at hybrid and electric cars due to the ability of the EMBs to be actuated as required (and do not
automatically produce brake force at pedal activation).
The target was to develop an EMB with low actuation force and energy that is simple and reliable, rolls back to disengage when power is off and acts as a parking brake. Several solutions were considered (with and without self-amplification). A pivotal mechanism with very high transmission ratio using eccentricity emerged as a favorable solution.
Vienna Engineering (VE) took over and assumed the research during 2010. VE revealed that non-linear behavior facilitated low actuation forces at high braking torque and can use a controlled amount of self-amplification. Unwanted actuation friction was minimized with roller bearings in the pivotal mechanism. Due to this very low friction and that no screws are used for actuation, it can roll back to disengaged at power off. Since self-amplification is not dominating the behavior the brake cannot seize and the drive direction need not be adjusted.
A test-rig with reduced rpm proved that the brake can produce real-world torque of a mid-size passenger car. Mathematical behavior of the offset mechanism including non-linearity, self-amplification and unwanted actuation friction was tested in a comprehensive simulation which was compared for consistency with the test-rig. It simulated one brake in three conditions: normal friction, high friction (e.g., to simulate rust or dust on the disc) and with much reduced friction with softened brake pads (to simulate overheating). Simulations showed that all cases can be
managed with actuation peak powers of about 180 W for full braking in 1/10th second.
Full dynamic testing at AIT has been undertaken with a dynamometer (315 kW, 3,000 min-₁ and 1,000 Nm continuous torque). The tests included comparison of reality and simulation, overheating and NVH tests.