Yamaha Hatsudoki Kabushiki Kaisha

Michiyasu Takahashi

Yuichiro Sawada

Hitoshi Hasegawa

Michihisa Nakamura

Daisuke Nonaka

Yuuichirou Sawada

Startability of an internal combustion engine using a mixed fuel of gasoline and alcohol is improved. An intake passage of the engine has a main flow channel provided with a throttle valve and a bypass flow channel for bypassing the throttle valve. A bypass quantity adjusting mechanism adjusts the bypass quantity in the bypass flow channel. A control device detects or estimates the mixing ratio of alcohol of the fuel and controls the bypass quantity adjusting mechanism so that a bypass quantity before a first explosion is smaller than a bypass quantity after the first explosion when the mixing ratio of alcohol is equal to or more than a predetermined value.

Control device for internal combustion engine and straddle type vehicle provided with the same

An unstable idling state immediately after engine start is stabilized. The difference between a target idling engine speed corresponding to the cooling water temperature and an actual engine speed is integrated. The ignition timing is changed toward advance or retard while using a value obtained by multiplying the integration value of the engine speed difference with a gain, as an ignition timing changing amount. Immediately after engine start, the gain is made relatively large to rapidly increase engine speed. When the engine speed approaches the target engine speed, the gain is set to a smaller usual gain, and, in a change to the same advancing or retarding side, a change to an ignition timing in the same side is suppressed using a smaller advancing or retarding gain. In a throttle-off state, an ignition timing corresponding to the cooling water temperature is set to rapidly reduce engine speed.

Engine controller

The atmospheric pressure is detected accurately without using an atmospheric pressure sensor. The atmospheric pressure is obtained from an intake air pressure just before an inlet valve opens by detecting an intake air pressure. Since the intake air pressure just before the inlet valve opens becomes unstable when the engine load is large, the atmospheric pressure is calculated from an intake air pressure just before the inlet valve opens when the engine load is small. In addition, since the intake air pressure just before the inlet valve opens depending upon engine rotational speeds, the atmospheric pressure is calculated from an intake air pressure just before the inlet valve opens when the engine rotational speed resides in a predetermined rotational speed area.

Atmospheric pressure detection device of four-stroke engine and method of detecting atmospheric pressure

To permit reliable occurrence of initial combustion at the start of an engine during which a stroke is not determined by only a crank pulse and to increase an engine speed. During a period from when cranking is started until a stroke is detected, fuel is injected once every rotation of a crankshaft before an intake stroke (or an expansion stroke), and ignition is effected once every rotation of the crankshaft in the vicinity of the top dead center, thereby enabling initial combustion without involvement of reverse rotation of the engine. If a stroke is detected, fuel injection and ignition are effected once per cycle. When the engine speed fails to become equal to or higher than a predetermined speed, the ignition timing is set to a point before the compression dead center and in the vicinity of 10&#xb0; toward advance, thereby immediately increasing the engine speed. Stroke detection is permitted when the engine speed has become equal to or higher than the predetermined speed, so that the engine speed becomes stable.

Engine control device

There is provided an engine start control method and an engine start control apparatus which can judge cell starting and kick starting with a simple constitution to perform optimum engine start according the respective starting. The engine start control method and the engine start control apparatus have a cell starting program at the time when an engine is started by a cell motor and a human power starting program at the time when the engine is started by a human power, detect a difference between a battery voltage at the time of engine stop and a battery voltage at the time of commencement of engine start, and starts the engine in accordance with the cell starting program if this difference is larger than a predetermined value and starts the engine in accordance with the human power starting program if the difference is smaller than the predetermined value.

Engine start control method and device

To accurately detect occurrence of erroneous detection of a crank pulse associated with dropout of a crank pulse or occurrence of noise. A cogless section is provided in cogs provided on an outer periphery of a crankshaft for transmitting a crank pulse. Occurrence of erroneous detection of a crank pulse is detected through use of an instantaneous rotational speed of the crankshaft computed from a crank pulse assigned to the cogless section and crank pulses assigned to cogs before and after the cogless section. When too few crank pulses are detected, a rapid increases arises in the instantaneous rotational speed of the crankshaft computed from the crank pulses after occurrence of a rapid decrease. The number of detected cramp pulses&#x2014;which are fewer than the original crank pulses&#x2014;is detected from the number of crank pulses existing between occurrence of a rapid decrease and occurrence of a rapid increase. When a too many crank pulses are detected, a rapid decrease arises in the instantaneous rotational speed of the crankshaft after occurrence of a rapid increase. The number of detected crank pulses&#x2014;which are greater in number than the original crank pulses&#x2014;is detected from the number of crank pulses existing between occurrence of a rapid increase and occurrence of a rapid decrease.

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Shizuoka, Japan

Michiyasu Takahashi