Mazda Motor Corporation

Yoshiteru Nakayama

Masahisa Yamakawa

Keiji Araki

Junichi Taga

Toshiaki Nishimoto

Masayuki Tetsuno

Tomomi Watanabe

Tatsuya Fujikawa

Hideki Hosoya

Takanori Sugiyama

Disclosed is a direct-injection spark-ignition engine designed to promote catalyst activation during cold engine operation. A fuel injection timing for a fuel injection period in an compression stroke (second fuel injection period F2) is set to allow a first fuel spray Ga injected from a first spray holeto enter a cavityin a piston crown surface, and allow a second fuel spray Gb to impinge against a region of the piston crown surfacelocated closer to an injector than the cavity, so as to cause the second fuel spray Gb having a lowered penetration force due to the impingement to be pulled toward the cavityby a negative pressure generated in the cavityas a result of passing of the first fuel spray Ga therethrough. The direct-injection spark-ignition engine can maximally hold an injected fuel spray around a spark plug to reliably stabilize a combustion state in a combustion mode for promoting catalyst activation during cold engine operation, while enhancing combustion efficiency in a homogenous combustion mode during normal engine operation.

Direct-injection spark-ignition engine

When an engine restart request is given in an engine stopping period which begins at a point of fuel supply interruption and ends at a point of complete engine stop, an engine starting system judges whether TDC engine speed detected immediately before is equal to or lower than a specific value 'A', the counted number of reverse running motions of the engine is 0, and a piston in an expansion stroke cylinder is relatively close to TDC. If the judgment result is in the affirmative with all these conditions satisfied, the engine starting system injects fuel into the expansion stroke cylinder and then ignites and combusts a mixture produced therein. The engine starting system also injects the fuel into a compression stroke cylinder and then ignites and combusts a mixture produced therein when a piston in the compression stroke cylinder has gone beyond TDC.

Engine starting system

Growing community of inventors

Hiroshima, Japan

Yoshiteru Nakayama