Control apparatus for engine

A control system for an engine, comprising:

• a valve configured to adjust an intake air filling amount for a cylinder according to an operation amount of an accelerator pedal;
• a sensor configured to output a measurement signal related to a temperature of an upper end of a cylinder head having an intake port and an exhaust port communicating with the cylinder;
• and
• a control circuit configured to
• set an upper limit value of the intake air filling amount to decrease as the temperature of the upper end of the cylinder head decreases based on the measurement signal of the sensor at a start of an engine, and
• output, to the valve, a control signal corresponding to the operation amount of the accelerator pedal within a range where the intake air filling amount does not exceed the upper limit value, wherein
• the cylinder head has a lubricating oil passage at the upper end of the cylinder head,
• the sensor is attached to the engine and outputs a measurement signal related to a temperature of lubricating oil to the control circuit,
• the control circuit is configured to set an upper limit value qa_limit of the intake air filling amount according to the following relational expression,
• qa
• ⁢
• limit
• =
• A
• ×
• Toil
• +
• B
• ×
• ε
• ⁢
• a
• +
• C
• where Toil is the temperature of lubricating oil, ε_a is a predetermined value of distortion of the cylinder head, and A, B, and C are constants, and
• the predetermined value of distortion is set as a value of distortion of the cylinder head in a range where no crack occurs to the cylinder head.

A control apparatus for an engine comprising:

• a control circuit configured to
• set an upper limit value of an intake air filling amount to decrease as a temperature of an upper end of a cylinder head decreases based on a measurement signal received from a sensor a start of an engine, the cylinder head having a lubricating oil passage at the upper end of the cylinder head and having an intake port and an exhaust port communicating with a cylinder, the sensor being attached to the engine, the measurement signal being related to a temperature of lubricating oil in the lubricating oil passage;
• output, to a valve configured to adjust an intake air filling amount for the cylinder according to an operation amount of an accelerator pedal, a control signal corresponding to the operation amount of the accelerator pedal within a range where the intake air filling amount does not exceed the upper limit value;
• set an upper limit value of the intake air filling amount for a cylinder according to an operation amount of an accelerator pedal to decrease as the temperature of the upper end of the cylinder head decreases based on the measurement signal at a start of an engine;
• and
• set an upper limit value ga limit of the intake air filling amount according to the following relational expression,
• qa
• ⁢
• limit
• =
• A
• ×
• Toil
• +
• B
• ×
• ε
• ⁢
• a
• +
• C
• where Toil is the temperature of lubricating oil, ε_a is a predetermined value of distortion of the cylinder head, and A, B, and C are constants, wherein
• the cylinder head has a lubricating oil passage at the upper end of the cylinder head,
• the sensor is attached to the engine and outputs a measurement signal related to a temperature of lubricating oil to the control circuit, and
• the predetermined value of distortion is set as a value of distortion of the cylinder head in a range where no crack occurs to the cylinder head.

A method of controlling an engine comprising, the method comprising:

• setting an upper limit value of an intake air filling amount to decrease as a temperature of an upper end of a cylinder head decreases based on a measurement signal received from a sensor at a start of an engine, the cylinder head having a lubricating oil passage at the upper end of the cylinder head and having an intake port and an exhaust port communicating with a cylinder, the sensor is attached to the engine, the measurement signal being related to a temperature of lubricating oil in the lubricating oil passage;
• and
• outputting, to a valve configured to adjust an intake air filling amount for the cylinder according to an operation amount of an accelerator pedal, a control signal corresponding to the operation amount of the accelerator pedal within a range where the intake air filling amount does not exceed the upper limit value
• setting an upper limit value ga limit of the intake air filling amount according to the following relational expression,
• qa
• ⁢
• limit
• =
• A
• ×
• Toil
• +
• B
• ×
• ε
• ⁢
• a
• +
• C
• where Toil is the temperature of lubricating oil, ε_a is a predetermined value of distortion of the cylinder head, and A, B, and C are constants,
• retrieving a relationship between the temperature of the upper end of the cylinder head at the start of the engine and the upper limit value of the intake air filling amount,
• setting a first upper limit value of the intake air filling amount based on the measurement signal of the sensor by using the relationship at the start of the engine,
• outputting a first control signal corresponding to the operation amount of the accelerator pedal within a range where the intake air filling amount does not exceed the first upper limit value,
• calculating a second upper limit value of the intake air filling amount by using the relational expression after the start of the engine,
• comparing the second upper limit value and the first upper limit value, and
• in response to the second upper limit value exceeding the first upper limit value, outputting, to the valve, a second control signal corresponding to the operation amount of the accelerator pedal within a range where the intake air filling amount does not exceed the second upper limit value.