The Effect of a Longer Stroke on Improving Fuel Economy of a Multiple-Link VCR Engine

Tsuchida, Hirofumi; Hiraya, Koji; Tanaka, Daisuke; Shigemoto, Shunsuke; Aoyama, Shunichi; Tomita, Masayuki; Sugiyama, Takanobu; Hiyoshi, Ryosuke

doi:10.4271/2007-01-4004

Cited by 14 publications

(5 citation statements)

References 8 publications

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“…The link mechanism adopted by the VC-Turbo engine, has in addition to enabling variable compression ratio functionality the effect of changing the motion of piston link [3,4]. Because of this effect the physical obstacle on the path to high compression ratio can be overcome and long stroke implemented geometrically and reasonable (Fig.…”

Section: Evolution Of Compression Ratio Of Gasoline Internal Combusmentioning

confidence: 99%

Nissan gasoline engine strategy for higher thermal efficiency

Mizuno

2017

Combustion Engines

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Rising highly concern about the environment has led to demands for the improvement of the efficiency of gasoline engines. Engine thermal efficiency will reach about 40% by technologies as boosted EGR, miller cycle and so on. This evolution trend will be continuously required to survive engines for the future. In this background, further improvement based on theoretical thermal efficiency of high compression ratio and specific heat capacity should be promoted. In addition, energy loss reduction such as represented by cooling loss and friction is also very important for the efficient and effective improvement. NISSAN’s challenges will be introduced to solve these propositions.

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Section: Evolution Of Compression Ratio Of Gasoline Internal Combusmentioning

confidence: 99%

Nissan gasoline engine strategy for higher thermal efficiency

Mizuno

2017

Combustion Engines

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“…A compromise between a dedicated and flex-fuel engine could be realized by using a variable compression ratio (VCR) to exploit the benefit of a high compression ratio for knock-resistant fuels and a reduced compression ratio for conventional gasoline and high loads. 19,20 However, its complexity makes the technology expensive. Naturally, the best performance is achieved with dedicated methanol engines.…”

Section: Introductionmentioning

confidence: 99%

Limits of compression ratio in spark-ignition combustion with methanol

Wouters

Burkardt

Pischinger

2021

International Journal of Engine Research

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A shift toward a circular and [Formula: see text]-neutral world is required, in which rapid defossilization and lower emissions are realized. A promising alternative fuel that has gained traction is methanol, thanks to its favorable and clean-burning fuel properties as well as its ability to be produced in a carbon-neutral process. Especially methanol’s high knock resistance and its combustion stability offer the opportunity to operate an engine at both a high compression ratio and a high excess air dilution. Although methanol has been investigated in series-production engines for passenger car applications, there is a lack of investigations on a dedicated engine that can operate at methanol’s knock limit. In this paper, methanol’s knock limitation is experimentally assessed by applying high compression ratios to a direct injection spark-ignition single-cylinder research engine. To that end, four compression ratios were investigated: 10.8, 15.0, 17.7, and 20.6. With compression ratios of 15.0 and 17.7, the lean-limit was increased to excess air ratios of 2.0 and 2.1, respectively, compared to 1.7 at a compression ratio of 10.8. For the highest compression ratio of 20.6, the maximum lean burn limit was increased to an excess air ratio of 1.9 due to achieving the maximum cylinder pressure limit. Despite the minor increase in lean-limit, a maximum indicated efficiency of 48.7% was achieved with the highest compression ratio of 20.6. However, even at this high compression ratio, methanol did not show a knock limitation. The investigations in this work provide profound knowledge for future engine investigations with methanol.

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“…As a result, a small B/S ratio design usually shows higher combustion efficiency and thermal efficiency. 8,9,11,[16][17][18][19][20] However, as the engine speed increases, the advantage of long stroke would be gradually lost as the friction loss significantly increases. 8 It is also reported that the reduced convection heat losses at part load could compensate the unfavorable surface/volume ratio for a ''square'' design with B/S ratio of 1, resulting in fuel consumption benefits by improving the reciprocating and rotating components stress and friction at high speed.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the effect of bore/stroke ratio and scavenge port angles on the scavenging process in a two-stroke boosted uniflow scavenged direct injection gasoline engine

Wang

Zhao

2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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In this study, a two-stroke boosted uniflow scavenged direct injection gasoline (BUSDIG) engine was proposed and researched to achieve aggressive engine downsizing and downspeeding. Compared to loop or cross scavenged twostroke engines, the BUSDIG engine can achieve excellent scavenging performance and be operated with higher boost pressure as well as the absence of air and fuel short-circuiting. As a fundamental engine geometric parameter, the bore/ stroke (B/S) ratio would directly affect the scavenging process in the uniflow scavenged two-stroke engine. Three-dimensional computational fluid dynamics simulations were used to investigate the scavenging process in the BUSDIG engine with different B/S ratios. Four B/S ratios of 0.66, 0.8, 1, and 1.3 were analyzed. The results indicate that a bigger B/S ratio leads to deteriorated swirl flow motion but better delivery ratio, scavenging efficiency, and charging efficiency. In order to fulfil the potential of the BUSDIG engine with different B/S ratios, two key scavenge port angles, i.e. axis inclination angle (AIA) and swirl orientation angle (SOA), were varied from the baseline design (AIA = 90°, SOA = 20°) to study their effects on the scavenging process for each B/S ratio design. Overall, a larger AIA leads to lower swirl ratio (SR) but achieves better scavenge performance, which is crucial for a large B/S ratio design. A small SOA design leads to noticeably lower SR but superior scavenging performances for a small B/S ratio design. An intermediate SOA, e.g. 10 and 20°, is preferred to improve the scavenging for a large B/S ratio design.

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The Effect of a Longer Stroke on Improving Fuel Economy of a Multiple-Link VCR Engine

Cited by 14 publications

References 8 publications

Nissan gasoline engine strategy for higher thermal efficiency

Nissan gasoline engine strategy for higher thermal efficiency

Limits of compression ratio in spark-ignition combustion with methanol

Analysis of the effect of bore/stroke ratio and scavenge port angles on the scavenging process in a two-stroke boosted uniflow scavenged direct injection gasoline engine

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