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 – 12/31/06

Background - Forthcoming emissions 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 and 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. Southwest Research Institute is collaborating 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 their 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 entailed 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 and 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 was tested in the laboratory. Despite several modifications the hardware did not operate as intended because of the additional damping of the valve imposed by the position sensors. Basic open loop control of the hardware was demonstrated using the dSpace controller and associated electronics. The fundamental control structure for advanced algorithm development was integrated into the controller. Additional modifications to the hardware are required to enable it to operate as intended and to complete the development of the control algorithms as originally planned.

2007 Program Home