Yamaha Hatsudoki Kabushiki Kaisha

Yuichiro Sawada

Michiyasu Takahashi

Hitoshi Hasegawa

Hiroshi Hasegawa

Michihisa Nakamura

A vehicle with a transmission having a crankshaft and an output shaft. A clutch located between the output shaft and a drive wheel is engaged and disengaged according to a rotational speed of the output shaft. An idle speed control device performs idle speed control to adjust an idle rotational speed of an engine. An electronic control unit (ECU) suppresses or stops the idle speed control when the clutch is engaged, or when an abnormality in the transmission is detected.

Vehicle and control device and control method thereof

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

An accelerated state is detected as soon as possible at the engine start at which a crank pulse alone is insufficient to identify the stroke, and erroneous detection of the accelerated state is prevented. In a period from cranking start to stroke detection, data on suction air pressure is stored for each crank pulse in a virtual address, and during stroke detection, when the virtual address does not coincide with the normal address corresponding to the stroke, the data on the suction air pressure stored in the virtual address is transferred to the normal address, and thereafter the data on the suction air pressure is stored in the normal address, thereby making it possible to detect the accelerated state by making comparison, immediately after the stroke detection, with the suction air pressure prevailing one cycle before. Further, detection of an accelerated state is inhibited when the engine rpm variation is high wherein the suction air pressure increase state during the closure of the suction air valve does not become stable and also when the engine load is high.

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.

An atmospheric pressure is obtained from an intake pressure resulting immediately before an intake stroke, an injection fuel pressure P is calculated which is constituted by a differential pressure between a fuel pressure which is supplied to an injector from the atmospheric pressure so obtained, a pump delivery pressure and the intake pressure and the intake pressure which is an injection atmosphere, a fuel injection time coefficient Q per unit mass which is metered when a reference injection fuel pressure is P is divided by a square root P of the injection fuel pressure to calculate a fuel injection coefficient Q , and a fuel injection time required to attain a desired air-fuel ratio is calculated using the fuel injection coefficient Q so calculated, whereby it is possible to realize a highly accurate control of the fuel injection time when a regulator for regulating an upper limit value for a fuel pump delivery pressure is provided on a fuel tank side.

4-Stroke engine control device and control method

An improved fuel injection and ignition control system for an engine, wherein the fuel injectors and ignition are controlled by respective circuits mounted on a common substrate but spaced from each other. The assembly is potted in a resin for electrical and heat insulation. The resulting control box can easily be mounted in the valley of a V-type engine in the powerhead of an outboard motor.

Growing community of inventors

Shizuoka, Japan

Yuichiro Sawada