Denso Corporation

Wakichi Kondo

Yukihiro Yamashita

Jun Hasegawa

Daiji Isobe

Hisashi Iida

Yasuo Sagisaka

Masahiko Yamaguchi

Johan Blom

A system and method cleans a fuel pump pressure control function valve having (i) an orifice linking a first region (e.g., a high pressure region) and a second region (e.g., a low pressure region) and (ii) a closing member biased to close the orifice when fuel pressure in the first region is below a threshold pressure. Cleaning the valve may include increasing the pressure in the first region to an overpressure condition, thereby causing the closing member to be moved to open the orifice such that a rapid flow of fuel occurs from the first region to the second region. A pressure control function valve can therefore be conveniently cleaned without requiring engine disassembly or adding additional physical elements. The fuel pump pressure control function valve may be part of safety or check valve of a fuel pump.

Cleaning a pressure control function valve

An engine has variable-valve mechanisms. An engine control system has an engine control unit for executing automatic stop and start control. At an automatic-stop, the variable-valve mechanisms are controlled to obtain a valve operation characteristic suitable for a restart of the engine. When a catalyst is in an inactivated state, the variable-valve mechanisms are controlled to reduce the amount of residual gas leaking out from cylinders. At an automatic-start, the control of the variable-valve mechanism is prohibited and an intake air is adjusted by using a throttle valve. At an automatic-stop, the engine speed is abruptly reduced so that the engine speed passes through a resonant revolution speed area in a short period of time. When the voltage of a battery is low, the control of the variable-valve mechanism may be prohibited.

Apparatus for controlling engine

A rate of cylinder-to-cylinder variations in an intake air quantity is calculated, and learned as a learning value based on an output from an airflow meter when a predetermined condition is met. The predetermined condition is set at a preferable condition for learning the rate of cylinder-to-cylinder variations. Subsequently, the rate of cylinder-to-cylinder variations is estimated based on the learning value when the predetermined condition is not met. Thus, cylinder-to-cylinder variations of an engine are accurately obtained in almost all the operating ranges, so that the measurement of the cylinder-by-cylinder intake air quantity with high degree of accuracy is achieved.

Cylinder-by-cylinder intake air quantity detecting apparatus for internal combustion engine

An apparatus for controlling an engine responds to the switching of combustion mode from stoichiometric combustion to lean-fuel combustion to vary the target throttle opening in step-wise fashion, causing the quantity of intake air to increase in a fashion of first-order delay. The base fuel injection quantity and base ignition timing are computed based on the response of intake air quantity. Consequently, the torque shock can be reduced and the quick combustion mode switching can be performed. Based on the quick passage of the air-fuel ratio zone in which a large amount of NOx arises, the amount of NOx emission can be reduced.

An apparatus for controlling an internal combustion engine controls an air amount bypassing a throttle valve of the engine. The air amount is decreased according to a difference between an actual rotational speed and a target rotational speed after a completion of a fuel-cut. Therefore, the rotational speed is quickly lowered. The decrease control is finished when the actual rotational speed reaches near a target rotational speed, simultaneously a feedback control is started. The feedback control accurately maintains the actual rotational speed at the target rotational speed. As a result, it is possible to improve fuel consumption and to prevent a stall and a vibration of the engine.

Apparatus for controlling internal combustion engine at decelerating state

In a fuel injection control system for an internal combustion engine, a fuel atomization device is provided to atomize fuel injected at the time of engine starting. The fuel atomization device may be a type which increases fuel pressure to a higher value at the time of engine starting than after the engine starting. Alternatively, the fuel atomization device may be a type which supplies assist air to the injected fuel. An intake valve is opened for a longer period at the time of engine starting than after the engine starting, so that more fuel may be supplied to an engine cylinder. A fuel leakage which may occur during engine stop is estimated, and the amount of fuel to be injected at the time of next engine starting after the engine stop is corrected by the estimated amount of fuel leakage. Fuel injection timing at the time of engine starting is retarded relative to that of post-engine starting. The amount of injected fuel adhered to an intake port and not supplied into an engine cylinder after the closing of the intake valve is estimated, and the amount of fuel to be injected next is corrected thereby.

Fuel injection control system of internal combustion engine

In a fuel injection control for engines, a basic transient correction coefficient is calculated to be used for correcting a basic fuel injection amount calculated based on intake air pressure. This transient correction coefficient is itself corrected by a further correction coefficient which corresponds to a fuel injection timing variable so as to overlap with the opening of an intake valve. The basic fuel injection amount is then corrected by the corrected transient correction coefficient to determine a final fuel injection amount. Thus, air-fuel mixture is controlled to a desired air-fuel ratio even when the engine is in a transient condition, thereby improving drivability and exhaust emissions.

Fuel injection control for engines responsive to fuel injection timing

An air/fuel ratio control system controls the supply of fuel to an internal combustion engine to achieve a target air/fuel ratio, based on the output of an air/fuel ratio sensor. The system may determine whether there is an abnormality in the air/fuel ratio sensor based on a comparison between a change of an air/fuel ratio correction coefficient, used to drive the air/fuel ratio to the target value, and a change of the target air/fuel ratio if the target air/fuel ratio has sharply changed. Alternatively, the diagnosis operation may be performed based on a comparison between a total air/fuel ratio correction amount and a change of the air/fuel ratio detected by the air/fuel ratio sensor, a phase difference calculation between peaks of the air/fuel ratio or the air/fuel ratio correction coefficient, or by accumulating the differences between the air/fuel ratio and the target air/fuel ratio, and the differences between the air/fuel ratio correction coefficient and a reference value, and comparing the accumulated values. In addition, the system may detect a sensor abnormality based on the deviation in phase of the air/fuel ratio from the air/fuel ratio correction coefficient. These diagnosis operations can precisely and easily detect the occurrence of an abnormality in the air/fuel ratio sensor. As a result, the air/fuel ratio control system will not use an imprecise output from the sensor for air/fuel ratio control, thus achieving highly precise and highly reliable air/fuel ratio control.

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Kariya, Japan

Wakichi Kondo