Global demand for better fuel economy, low engine emissions, and better vehicle response speed require engines with better combustion systems. A common rail diesel engine using direct fuel injection technology led to a significant improvement in emissions, fuel consumption and power density. A key constituent of such system is a Piezoelectric fuel injectors consisting of a multi-layer piezoelectric stack actuator acting on a nozzle with a speed 4~5 times faster than the older solenoid counterpart. In this project, a direct mechanical acting piezoelectric fuel injection technology is being developed based on a novel large stroke compact multi-stack piezoelectric actuator with the injection nozzle needle directly connected to the actuator and without any amplification mechanisms. The new actuator when developed will also feature self-sensing capability and temperature compensation in order to enhance the control of the fueling process. This improved combustion control will lead to a further reduction in emissions, higher torque and improved fuel economy.
The fuel injector program at MMDL started in November 2009. MMDL is part of a large consortium of Universities and Industries that are working together on this project.
Objectives of Program
- Develop a novel compact piezo actuator suitable for integration into injectors. The actuator needs to provide a stroke of 300 μm and provide a sufficiently high stiffness while operating under high engine pressures and a fast response time.
- Develop a self-sensing mechanism and control algorithm to realize closed-loop control of the injection motion.
- Development of efficient electric driving modules for piezoceramic actuators especially designed for the automotive environment and develop temperature compensation algorithms for the piezoceramic stacks while operating in the engine.