Load Control Using Late Intake Valve Closing in a Cross Flow Cylinder Head

Fredrik Söderberg; Bengt Johansson

doi:10.4271/2001-01-3554

2001-09-24

Load Control Using Late Intake Valve Closing in a Cross Flow Cylinder Head 2001-01-3554

A newly developed cross flow cylinder head has been used for comparison between throttled and unthrottled operation using late intake valve closing. Pressure measurements have been used for calculations of indicated load and heat-release. Emission measurements has also been made. A model was used for estimating the amount of residual gases resulting from the different load strategies.

Unthrottled operation using late intake valve closing resulted in lower pumping losses, but also in increased amounts of residual gases, using this cylinder head. This is due to the special design, with one intake valve and one exhaust valve per camshaft. Late intake valve closing was achieved by phasing one of the camshafts, resulting in late exhaust valve closing as well. With very late phasing - i.e. low load - the effective compression ratio was reduced. This, in combination with high amount of residual gases, resulted in a very unstable combustion.

The main combustion, 10-90% heat-release, was quite fast for all load control strategies, indicating high turbulence. This could not be seen in the early combustion, however.

An increase in fuel conversion efficiency could be achieved with up to 9%. The emissions of NO_x were reduced by 4-5 g/kWh with LIVC for loads between 4-8 bar IMEP_net.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Digital $37.00 Print $37.00

Preview Document

We also recommend:

Standards

SAE Mobilus®

Publications

News

Events

Professional Development

A World in Motion (PreK-12)

Participate with SAE

SAE Membership

Donate

Load Control Using Late Intake Valve Closing in a Cross Flow Cylinder Head 2001-01-3554

SAE MOBILUS