Mazda Motor Corporation

Shuji Oba

Masahisa Yamakawa

Kouhei Iwai

Kazuhiro Nagatsu

Noriyuki Ota

Naoya Watanabe

Hiroyuki Kurita

Takashi Youso

Takaaki Nagano

Kazutoyo Watanabe

Kenji Uchida

Yoshihisa Nou

Tatsuya Fujikawa

Tatsuya Koga

Daisuke Asaji

A control device of a spark-ignition gasoline engine is provided. The control device includes a controller for operating the engine body by controlling at least a fuel injection valve, an ignition plug, and a fuel pressure variable mechanism. Depending on the engine load range, the controller sets the combustion mode to a compression-ignition mode or a spark-ignition mode. In each mode, the controller also controls the fuel pressure, and the timing of fuel injection and ignition. The controller may also performs external EGR control in each mode.

Control device of spark-ignition gasoline engine

An engine is designed to allow a compression self-ignition combustion under an air-fuel ratio leaner than a stoichiometric air-fuel ratio to be performed at least in a partial-load range of the engine. Under a condition that an engine speed varies at a same load in an engine operating region of the compression self-ignition combustion, a compression end temperature Tx, which is an in-cylinder temperature just before an air-fuel mixture self-ignites, is controlled to be raised higher in a higher engine speed side than in a lower engine speed side. As one example of control for the compression end temperature Tx, an internal EGR amount is controlled to be increased larger in the higher engine speed side than in the lower engine speed side, to raise a compression initial temperature Twhich is an in-cylinder temperature at a start timing of a compression stroke. This makes it possible to perform the compression self-ignition combustion under a lean air-fuel ratio in a wider engine speed range to effectively enhance engine thermal efficiency.

Engine control method and apparatus

The disclosure provides a control device of a spark-ignition gasoline engine. When an operating state of an engine body is within a low engine speed range, a controller controls a fuel pressure variable mechanism so that a fuel pressure is higher within a high engine load range compared to a low engine load range, the controller operates, within the high engine load range, a fuel injection valve to perform a fuel injection at least at a timing that is more retarded than an injection timing of a fuel within the low engine load range and is within a retard period from a late stage of a compression stroke to an early stage of an expansion stroke, and the controller operates, within the high engine load range, an ignition plug to ignite at a timing within the retard period and further after the fuel injection.

The disclosure provides a control device of a spark-ignition gasoline engine. When an operating state of an engine body is within a low engine speed range, a controller operates a fuel pressure variable mechanism so that a fuel pressure is higher within a high engine load range compared to a low engine load range, the controller operates, within the high engine load range, a fuel injection mechanism to perform at least a fuel injection into the cylinder by a cylinder internal injection valve at a timing during a retard period from a late stage of a compression stroke to an early stage of an expansion stroke, and the controller operates, within the high engine load range, an ignition plug to ignite at a timing during the retard period and after the fuel injection.

A supercharged engine has a geometric compression ratio ser to 16 or more and is designed to perform a compression self-ignition combustion under an air-fuel ratio leaner than a stoichiometric air-fuel ratio at least in a low engine speed range. On a lower engine load side than a given engine load within an engine operating region at which the compression self-ignition combustion is performed, a fresh air amount is reduced and an effective compression ratio (&#x3b5;') is increased, as compared with a higher engine load side than the given engine load within the engine operating region, and, on the higher engine load side than the given engine load, a supercharging pressure based on a supercharger () is increased to increase the fresh air amount, and the effective compression ratio (&#x3b5;&#x2032;) is reduced, as compared with the lower engine load side than the given engine load. This makes it possible to perform the compression self-ignition combustion under a lean air-fuel ratio in a wider engine load range to effectively enhance engine thermal efficiency, while eliminating a need for an operation of forcedly raising/lowering a temperature of fresh air.

Method and apparatus for controlling supercharged engine

In a specified operating area including a low engine-speed and low engine-load area, an excess air ratio &#x3bb; is set at a specified ratio which is two or greater and three or smaller and an ignition timing &#x3b8;ig of a spark plug is set at a timing of MBT to provide the maximum torque as a normal combustion control (S). In case a catalyst temperature Tc is lower than a predetermined first temperature Tin this area, a control of retarding the ignition timing from the MBT timing and/or a control of decreasing the excess air ratio &#x3bb; to a ration below the above-described ratio are executed (S, S, S). Accordingly, the temperature of the catalyst can be prevented simply and effectively from decreasing excessively, maintaining combustion conditions to provide a properly high thermal efficiency.

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Kariya, Japan

Shuji Oba