Engine control device and engine control method

1. An engine control device, comprising:

a throttle valve provided in an intake pipe of an engine;

an intake pressure sensor which detects an intake pressure inside the intake pipe on a downstream side of the throttle valve;

a crank angle sensor which detects a crank angle of a crankshaft of the engine; and

a microcomputer comprising a fuel injection control unit which controls an amount of fuel injected to a cylinder of the engine, based on the intake pressure detected by the intake pressure sensor,

wherein the fuel injection control unit includes:

a first transience determination unit which calculates, as a first intake pressure differential integration value, an integrated value of an amount of change in the intake pressure in a first section that consists of a compression stroke, an expansion stroke and a former part of an exhaust stroke, of a combustion cycle of the engine, and which determines an accelerating state of the engine when the first intake pressure differential integration value is greater than a first acceleration determination threshold value;

a first transient fuel injection amount calculation unit which calculates a first transient fuel injection amount based on the first intake pressure differential integration value;

a second transience determination unit which calculates, as a second intake pressure differential integration value, an integrated value of an amount of change in the intake pressure in a second section that consists of a latter part of the exhaust stroke and an intake stroke subsequent to the exhaust stroke, of the combustion cycle of the engine, and which determines an accelerating state of the engine when the second intake pressure differential integration value is greater than a second acceleration determination threshold value which is smaller than the first acceleration determination threshold value; and

a second transient fuel injection amount calculation unit which calculates a second transient fuel injection amount based on the second intake pressure differential integration value.

2. The engine control device according to claim 1 ,

wherein, in the first section, the first transience determination unit calculates the first intake pressure differential integration value by integrating, in the first section, a differential between a current intake pressure and an intake pressure for one period previously; and

in the second section, the second transience determination unit calculates the second intake pressure differential integration value by integrating, in the second section, a differential between a current intake pressure and an intake pressure for one period previously.

3. The engine control device according to claim 1 , wherein the second transient fuel injection amount calculation unit is capable of determining the second transient fuel injection amount which is larger than the first transient fuel injection amount determined by the first transient fuel injection amount calculation unit, in relation to the same intake pressure differential integration value as the intake pressure differential integration value calculated by the first transient fuel injection amount calculation unit.

4. The engine control device according to claim 2 , wherein the second transient fuel injection amount calculation unit is capable of determining the second transient fuel injection amount which is larger than the first transient fuel injection amount determined by the first transient fuel injection amount calculation unit, in relation to the same intake pressure differential integration value as the intake pressure differential integration value calculated by the first transient fuel injection amount calculation unit.

5. The engine control device according to claim 1 , wherein the second transient fuel injection amount calculation unit reduces the second transient fuel injection amount in a case where the accelerating state of the engine is determined by the first transience determination unit, compared to a case where the accelerating state of the engine is not determined by the first transience determination unit.

6. The engine control device according to claim 2 , wherein the second transient fuel injection amount calculation unit reduces the second transient fuel injection amount in a case where the accelerating state of the engine is determined by the first transience determination unit, compared to a case where the accelerating state of the engine is not determined by the first transience determination unit.

7. The engine control device according to claim 3 , wherein the second transient fuel injection amount calculation unit reduces the second transient fuel injection amount in a case where the accelerating state of the engine is determined by the first transience determination unit, compared to a case where the accelerating state of the engine is not determined by the first transience determination unit.

8. The engine control device according to claim 4 , wherein the second transient fuel injection amount calculation unit reduces the second transient fuel injection amount in a case where the accelerating state of the engine is determined by the first transience determination unit, compared to a case where the accelerating state of the engine is not determined by the first transience determination unit.

9. An engine control method performed in an engine control device that includes:

a throttle valve provided in an intake pipe of an engine;

an intake pressure sensor which detects an intake pressure inside the intake pipe on a downstream side of the throttle valve;

a crank angle sensor which detects a crank angle of a crankshaft of the engine; and

a fuel injection control unit which controls an amount of fuel injected to a cylinder of the engine, based on the intake pressure detected by the intake pressure sensor,

the method comprising:

a first transience determination step of calculating, as a first intake pressure differential integration value, an integrated value of an amount of change in the intake pressure in a first section that consists of a compression stroke, an expansion stroke and a former part of an exhaust stroke, of a combustion cycle of the engine, and determining an accelerating state of the engine when the first intake pressure differential integration value is greater than a first acceleration determination threshold value;

a first transient fuel injection amount calculation step of calculating a first transient fuel injection amount based on the first intake pressure differential integration value;

a second transience determination step of calculating, as a second intake pressure differential integration value, an integrated value of an amount of change in the intake pressure in a second section that consists of a latter part of the exhaust stroke and an intake stroke, of the combustion cycle of the engine, and determining an accelerating state of the engine when the second intake pressure differential integration value is greater than a second acceleration determination threshold value which is smaller than the first acceleration determination threshold value; and

a second transient fuel injection amount calculation step of calculating a second transient fuel injection amount based on the second intake pressure differential integration value.