Development of Algorithms for the Control of the Camless Valvetrains of a Single-Cylinder, Four-Valve Engine, 03-R9488

Principal Investigator
Glenn R. Wendel

Inclusive Dates:  07/01/04 – Current

Background - Forthcoming emission legislation and the demands for improved vehicle performance and fuel economy are pushing designers to increase the technology content of modern engines and to investigate novel engine operating modes. A key factor in this development is to be able to arbitrarily adjust timing, lift, and phasing of intake/exhaust valves so that the gas exchange process can be managed. Independent and fully flexible control of all engine valves is possible with “camless” valve actuation. Camless actuation is an enabling technology that offers a variety of improvements to include increase in fuel economy, reduction in exhaust emissions, complete engine redesign with improved packaging, synergy with hybrid vehicles, power increase, and greater flexibility in terms of torque shaping. The Institute has the opportunity to collaborate with a major automotive supplier in developing a unique regenerative hydraulic camless valvetrain that has low energy consumption and represents a significant improvement in the state-of-the-art.

Approach - The automotive supplier has developed and demonstrated its camless valvetrain hardware in open-loop bench testing. However, an advanced control system is a recognized need for reliable, accurate, and predictable operation before it can be applied to a development engine. This project would entail detailed modeling and simulation of the camless valvetrain, the development of control algorithms using the models, fabrication of a set of test hardware with appropriate sensors, and the performance of laboratory tests on a simulated engine setup to fine tune the algorithms. The technical challenge is to develop a control system and sophisticated algorithm that will ensure accurate timing of the valve opening/closing events as well as accurate valve lift and soft controlled valve seating. This algorithm must compensate for manufacturing tolerances, temperatures, and quality of hydraulic fluid.

Accomplishments - Camless valvetrain hardware was designed and procured to actuate the two exhaust valves of a spark ignition engine. The hardware included position sensors and pressure sensors to monitor parameters to aid in developing the algorithms. The hardware is currently being prepared for laboratory testing, connecting the hydraulic supply and the dSpace controller associated electronics. The fundamental control structure has been integrated into the controller. Advanced algorithms will be applied and developed to improve the control to meet the project objectives through the remainder of the project.

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