The requirements on vehicle emission control are more and more demanding. In order to meet these emission control requirements, internal combustion engines need to be more and more efficient and so require new electronic engine management features. These innovative solutions on engine management are usually based on electrically actuated or regulated valves, pumps and turbines. We have developed Brushless DC (BLDC) actuator designs dedicated to high temperature engine environment on applications like Exhaust Gas Recirculation (EGR) valve or Variable Geometry Turbo (VGT). These actuators encompass a patented low cost design of BLDC motor, a reversible motion transformation, and a high temperature drive electronic. Additional optional features like fail-safe return spring, analog position sensor or clutch can also be added in the actuator. This presentation will show the detail of the patented BLDC structure with an integrated position encoder, the integration of all these sub-assemblies for each feature in different actuator embodiments and the benefits of such actuators in applications like electric EGR valves or VGT electrically actuated. This paper will also present the possibility to decrease the cost of the drive electronic by developing an application dedicated ASIC integrating a standard three phase BLDC drive and all the specific features necessary in an automotive application like LIN or CAN communication.

<div class="section abstract"><div class="htmlview paragraph">Expansion valves are key components of an automotive thermal management system. Recently electronic expansion valves (EXVs) have been replacing conventional thermostatic valves as they offer a finer degree of control. They are operated by a stepper motor and can be based either on a linear or a rotary motion. However, on one hand, the existing linear EXVs with a leadscrew system are not suitable to manage high-pressure and large-diameter port valves, and on the other hand, rotary EXVs have the main disadvantages of having a high mechanical hysteresis and of requiring a dynamic seal which adds cost to the system. This paper proposes then to solve those issues thanks to a new linear concept that provides a new integration on a classic leadscrew linear EXV using a specific radial flux brushless DC (BLDC) motor, a worm gear, and a sensor integration option. The idea behind this is to stop using the conventional coaxial movements of the reducers and to better use the volume of the metal body where the fluid lines are located. The main benefit is a more compact EXV that can generate more force than the standard solutions. Moreover the integration of a position sensor and a new control scheme led to an increase in the accuracy of the valve positioning and to a global efficiency improvement of the system by being able to adapt the current to the applied load. For comparison purposes, an actuator based on this new concept was then built using two existing EXVs as references. This comparison shows that to reach the same performances, the new linear design needs a much smaller motor and, has an overall height of only 55 mm compared to 80 mm and a theoretical resolution of 0.16 μm.</div></div>

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