Apparatus for computing the amount of intake air in internal combustion engine

A device for determining an amount of an air introduced to a cylinder of an engine, said cylinder communicating with an air-intake passage and an air-exhaust passage, said air-intake passage being arranged to introduce the air to the cylinder, said air-exhaust passage being arranged to exhaust gas from the cylinder, both passages respectively having an intake valve and an exhaust valve therein, both valves being respectively driven by an intake valve drive mechanism and an exhaust valve drive mechanism in accordance with a rotation of a crank shaft to alternatively and selectively open and close, and to remain open during a valve overlap period to open the passages to the cylinder, said engine including a variable valve timing mechanism, and wherein said variable valve timing mechanism controls an operational timing of at least one of the valve drive mechanisms with respect to the crank shaft in accordance with a running condition of the engine to vary a timing of the valve driven by at least one of the valve drive mechanisms, said device comprising:

• first detecting means for detecting a rotational speed of the crank shaft;
• second detecting means for detecting an intake pressure in the air-intake passage;
• third detecting means for detecting the operational timing of at least one of the valve drive mechanisms;
• calculating means for calculating a displacement of the operational timing according to the detected rotational speed of the crank shaft and the detected operational timing;
• and
• fourth detecting means for detecting an atmospheric pressure;
• fifth detecting means for detecting a coolant temperature for the engine;
• sixth detecting means for detecting a temperature of the air introduced to the air-intake passage;
• first computing means for computing an amount of the air introduced to the cylinder in response to the rotational speed of the crank shaft, the intake pressure, the displacement of the operational timing, and the atmospheric pressure, said first computing means computing a charging efficiency of the air to be charged in the cylinder in response to the rotational speed of the crank shaft, the intake pressure, and the displacement of the operational timing when computing the amount of the air, wherein said charging efficiency is represented by a ratio of a weight of the air actually introduced to the cylinder to the weight of the air to be introduced to the cylinder under a standard air condition;
• an injector for injecting a fuel to the cylinder;
• second computing means for computing an injection time of the fuel responsive to the amount of the air;
• control means for controlling the injector in response to the injection time;
• speed determining means for determining whether the rotational speed of the crank shaft reaches a predetermined value;
• third computing means for computing the injection time in response to the coolant temperature, the temperature of the air, and the atmospheric pressure when said speed determining means determines that the rotational speed of the crank shaft does not reach the predetermined value;
• and
• wherein said first computing means computes the amount of the air when said second determining means determines that the rotational speed reaches the predetermined value.

A device for determining an amount of an intake air introduced to a cylinder of an engine, said cylinder communicating with an air-intake passage and an air-exhaust passage, both passages respectively having an intake valve and an exhaust valve therein, both valves being respectively driven by valve drive mechanisms to selectively open and close, and to remain open during a valve overlap period to open the passages to the cylinder, said engine including variable valve timing means for controlling an operational timing of at least one of the valve drive mechanisms with respect to a crank shaft to vary a timing of at least one of the valves, said device comprising:

• first detecting means for sensing crank shaft rotation and detecting a rotational speed of the crank shaft;
• second detecting means for detecting an intake pressure in the air-intake passage;
• third detecting means for detecting the operational timing of at least one of the valve drive mechanisms;
• calculating means for calculating a displacement of the operational timing according to the detected rotational speed of the crank shaft and the detected operational timing;
• and
• computing means for computing an amount of the air introduced to the cylinder in response to the rotational speed of the crank shaft, the intake pressure, and the displacement of the operational timing.