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Development of a Hydraulic Variable Valve Timing Control System with an Optimum Angular Position Locking Mechanism
Technical Paper
2012-01-0416
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
This paper describes a newly developed hydraulic variable valve timing control (VTC) system, targeting the internal combustion gasoline engine, with an optimum angular position locking mechanism to reduce tailpipe emissions (TPE).
In general, emission control catalysts are used as one measure to reduce TPE. However, there is the issue that catalysts cannot remove pollutants before reaching its light-off temperature at cold engine start. To address this issue, we have been using a method of increasing the valve overlap period between intake valve opening (IVO) and exhaust valve closing (EVC) by operating a VTC system at engine start. This brings engine-out emissions (EOE) back to the combustion chamber to be burned, thereby reducing EOE levels.
However, this method requires about 3 seconds for the sufficient hydraulic pressure to start VTC operations. Additionally, the air-to-fuel ratio at engine start is calibrated to a rich condition to maintain combustion stability, which also increases EOE. The amount of EOE at this time accounts for a substantial portion of the total emissions in an emission test.
Therefore, we have developed a new VTC system that adds a function for locking the initial phase at an optimum angular position within the control range before the engine starts. This paper explains the operating principle of the new VTC system with an optimum angular position locking mechanism and the EOE reduction obtained by increasing valve overlap and other resultant effects.
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Authors
- Takahiro Miura - Nissan Motor Company Ltd.
- Shunichi Aoyama - Nissan Motor Company Ltd.
- Kaoru Onogawa - Nissan Motor Company Ltd.
- Takaya Fujia - Nissan Motor Company Ltd.
- Tetsuro Murata - Nissan Motor Company Ltd.
- Kenji Ariga - Nissan Motor Company Ltd.
- Ken shiozawa - Nissan Motor Company Ltd.
- Kazunari Adachi - Aisin Seiki Co Ltd
- Masaki Kobayashi - Aisin Seiki Co Ltd
Citation
Miura, T., Aoyama, S., Onogawa, K., Fujia, T. et al., "Development of a Hydraulic Variable Valve Timing Control System with an Optimum Angular Position Locking Mechanism," SAE Technical Paper 2012-01-0416, 2012, https://doi.org/10.4271/2012-01-0416.Also In
References
- Suzuki, Shigemitsu, “VALVE OPENING/CLOSING TIMING CONTROL APPARATUS,” U.S. Patent 2010/0175649 A1, July 15, 2010.
- Fujiwaki, Kenji, “VARIABLE VALVE TIMING DEVICE,” U.S. Patent 5,901,674, May 11, 1999.
- Ogawa, Kazumi, “VARIABLE VALVE TIMING SYSTEM,” U.S. Patent 6,450,137 B2, Sep 17, 2002.
- Komazawa, Osamu, “VARIABLE VALVE TIMING CONTROL DEVICE,” U.S. Patent 6,976,460 B2, Dec 20, 2005.
- Tabaczynski, R., Heywood, J., and Keck, J., “Time-Resolved Measurements of Hydrocarbon Mass Flowrate in the Exhaust of a Spark-Ignition Engine,” SAE Technical Paper 720112, 1972, doi: 10.4271/720112.