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The Mitsubishi 4A9 engine is the newest family range of all-alloy inline four-cylinder engines from Mitsubishi Motors, introduced in the 2004 version of their Mitsubishi Colt supermini, and built by DaimlerChrysler-owned MDC Power in Germany (previously a joint venture).〔("Newly Developed Compact, Aluminum Gasoline Engine" ), Mitsubishi Motors technical review〕〔("Mitsubishi Motors Corporation and DaimlerChrysler AG have signed agreements concerning the production halt of the smart forfour" ), Mitsubishi Motors press release〕 The engine project was begun as a joint effort by Mitsubishi Motors and DaimlerChrysler (DCX), with Mitsubishi handling the development of the engines and MDC Power GmbH, a company previously jointly established by Mitsubishi and DCX, handling production. The 4A9 is Mitsubishi's first four-cylinder engine family to adopt a high-pressure die-cast aluminum block.〔〔("Colt Plus gets MDC Power" ), Jack Yamaguchi, ''SAE International''〕 All engines developed within this family have aluminum cylinder block and head, four valves per cylinder, double overhead camshaft layouts, and ''MIVEC'' continuous variable valve timing (intake only). ==Engine family characteristics== For high output and low fuel consumption, the MIVEC system and other measures (including optimized shaping of the intake and exhaust manifolds and cylinder head) were used to promote intake and exhaust efficiency. Optimally shaped cooling passages in the cylinder head and optimal control of the flow of coolant into the cylinder head help to suppress engine knocking. Comprehensive measures to engine components were taken to minimize friction.〔 For lightness and compactness; design optimization, material optimization, and component integration were identified as effective means of minimizing weight and bulk, so they were comprehensively effected in combination with each other. With regard to materials, the cylinder block is made of aluminum; the cylinder-head cover and intake manifold are made of plastic; the exhaust manifold has a pipe-based structure and cams driven by a timing chain. Component integration was applied in many areas of the engine. Notably, the functions of engine accessories were integrated into the cylinder block.〔 Exhaust emissions from the engine are minimized by measures including optimal design of the combustion chambers, optimal control of the intake air motion by means of the cylinder-head ports, employment of the MIVEC system, employment of an ultra-thin cylinder head gasket, and employment of micro-droplet fuel injectors. The vehicle's overall exhaust emissions are further suppressed by location of the exhaust manifold at the rear of the engine. This layout is beneficial since it minimizes the heat capacity of the exhaust system upstream of the catalytic converter and thus, together with combustion control, promotes activation of the catalytic converter.〔 4A91's DOHC camshafts are driven by a single-stage roller chain of 8.0 mm (0.3 in) pitch and 12.5 mm (0.5 in) width, instead of the previous 4G15's cogged belt drive. Camshafts act directly on bucket-type tappets. The intake camshaft is fitted with a continuously variable cam-phasing, altering timing up to 50 degrees. Valves are inclined at an included angle of 34 degrees versus the 4G15's wider 45 degrees.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mitsubishi 4A9 engine」の詳細全文を読む スポンサード リンク
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