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Seo, Takehiko
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The Influence of Connecting-Rod Specifications on the Combustion-Noise Generation from a Diesel Engine

Yamaguchi University-Hitoshi Oguchi, Koki Minato, Takehiko Seo, Masato Mikami
Published 2019-06-05 by SAE International in United States
We experimentally investigated the influence of shifting natural frequencies of the internal transmission system depending on the connecting-rod specifications on the characteristics of noise radiated from a single-cylinder diesel engine. We used FFT analysis to investigate the influence of shifting natural frequencies of the internal transmission system on the radiated noise characteristics. By changing the thinned portion of the connecting-rod, we confirmed that the natural frequency of the piston-connecting-rod-coupled vibration differed from another natural frequency of the engine structure, and thus the engine noise was reduced. This research studied the time-frequency characteristics of combustion impact and engine noise by wavelet analysis of in-cylinder pressure and sound pressure. We examined the vibration-transmission characteristics through the relationship between the maximum engine noise power and the maximum combustion energy in the same cycle for the main frequencies of combustion noise. Two types of connecting-rods were used: the original connecting-rod and a connecting rod that has a short-thinned portion (STP). By shortening the thinned portion of the connecting-rod, the natural frequency of the piston-connecting-rod-coupled vibration became around 2800 Hz…
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Combustion and Noise Characteristics in a Diesel Engine with Hydrogen Addition and Pilot Injection

Yamaguchi University-Ryota Sakane, Toshiki Fujimura, Takehiko Seo, Masato Mikami
Published 2015-09-01 by SAE International in United States
We experimentally investigated effects of pilot diesel-fuel injection on ignition timing variation and noise reduction in a diesel engine with hydrogen addition to the intake pipe. The pilot diesel-fuel injection suppressed ignition timing variation which was significant under hydrogen addition conditions. The heat release by the pilot diesel-fuel injection stably acted as an ignition source of the hydrogen-air mixture. The maximum in-cylinder pressure rise rate increased with the hydrogen fraction. However, the sound pressure level attained minimum around a specific hydrogen fraction.
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Effects of Hydrogen Addition to Intake Mixture on Cyclic Variation of Diesel Engine

Honda R&D Co., Ltd.-Hajime Kabashima, Tomoyuki Hashimoto
Yamaguchi Univ.-Toru Miyamoto, Hirokazu Hasegawa, Takashi Yagenji, Takehiko Seo, Masato Mikami
Published 2011-08-30 by SAE International in United States
The present study experimentally investigated cyclic variation of combustion characteristics of a diesel engine with hydrogen added to the intake air in detail. As the result, there were three ignition modes: (1) hydrogen ignition mode, (2) hydrogen-assisted ignition mode, and (3) diesel-fuel ignition mode. Ignition timing fluctuated from cycle to cycle in each ignition mode and between one ignition mode and another mode. As the coolant temperature was increased, the number of cycles in diesel-fuel ignition mode decreased, and indicated thermal efficiency and cyclic variation was improved. In the case with the blow-by gas introduced to intake port, preflame reaction of blow-by gas first occurred, ignited hydrogen, and then diesel-fuel was ignited by hydrogen combustion in hydrogen ignition mode and hydrogen-assisted ignition mode.
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