For over 15 years, JVS Engineering has been making Variable Valve Actuation (VVA) systems with a sophisticated electronic controller—the Valve Control Unit (VCU). Engine OEMs use VVA technology to optimize engine performance, fuel economy, and engine emissions. Final production systems are highly customized for cost based on each engine maker’s specific requirements, but for quickly introducing VVA technology into a development program, a more configurable VCU was required.
The challenge facing JVS Engineering was to design a single, highly configurable VCU that could be used by all OEM’s designing VVA technology.
VVA requires accurate control of engine intake and exhaust valves, which in turn requires an electronic controller with the capability to drive high-speed, high-current solenoids. Environmental issues such as electromagnetic interference, or the high temperature, humidity, and vibration in an engine compartment, also drove some of the VCU requirements.
The VCU was designed concurrently with the mechanical system to provide significant valve control flexibility. Using a state-of-the-art microprocessor with a dedicated interface for engine timing signals, JVS software engineers developed algorithms that achieve a high level of valve-control accuracy by dynamically calculating timing offsets based on cycle-to-cycle engine conditions.
The VCU can produce valve timings in response to data from the Engine Control Unit (ECU) via the industry-standard CAN bus and is reconfigurable in real time. It can also function autonomously (without signals from the ECU) such as when performing system functional testing to confirm the operation of a complete cylinder head on a test rig.
Supporting the valve control algorithms, JVS electronics engineers designed a flexible, rugged solenoid-valve driver that can be configured by the microprocessor to virtually any imaginable drive scheme so that the highest speed valve operation can be achieved. Configurable also to a wide range of current outputs, this driver is highly fault-tolerant. With six high-speed valve drivers, each VCU can be configured for 4- and 6-valve applications; up to four VCUs can be used in an engine to control up to 24 valves.
Delivered to a variety of customers, VVA development is now worldwide. In each new application, the flexibility and robustness of the system is again demonstrated. Meanwhile, JVS engineers are using this configurable VCU plus newer technologies as the baseline for optimized VCUs for production applications.
Leveraging our knowledge base with advances in technology to achieve simultaneously lower cost and high quality for high-reliability production applications is just another thing that JVS engineers know how to do.