Apparatus and method for diagnosing variable valve timing apparatus
AssigneeUnisia Jecs Corporation
InventorsHaruhiro Iwaki, Hajime Hosoya
Life of this patent
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Abstract
In a variable valve timing apparatus for variably controlling the valve timing by changing a rotation phase of a camshaft with respect to a crankshaft, an abnormality diagnosis of the apparatus is performed on a condition that a change amount per unit time in a control target value of the rotation phase has been kept equal to or less than a predetermined limit value for a predetermined period or more.
Claims14
An apparatus for diagnosing a variable valve timing apparatus comprising:
- a variable valve timing apparatus which comprises,
- a camshaft for driving an intake valve and an exhaust valve of an internal combustion engine to be open/close,
- a valve timing adjustment mechanism for variably controlling a rotation phase of said camshaft with respect to a crankshaft, to adjust the valve timing of said intake valve and exhaust valve;
- a change amount calculation unit for calculating a change amount per unit time in a control target value of said rotation phase;
- a comparison unit for comparing said calculated change amount with a predetermined limit value;
- a diagnosis permission unit for permitting an abnormality diagnosis of said variable valve timing apparatus on a condition that said change amount has been kept equal to or less than said predetermined limit value for a predetermined period by said comparison of said comparison unit;
- and
- a diagnosis unit for diagnosing an abnormality of said variable valve timing apparatus when said diagnosis permission unit permits said abnormality diagnosis.
A method for diagnosing a variable valve timing apparatus which comprises a variable valve timing adjustment mechanism for variably controlling a rotation phase of a camshaft with respect to a crankshaft, to adjust the valve timing of an intake valve and an exhaust valve of an internal combustion engine, comprising:
- calculating a change amount per unit time in a control target value of said rotation phase;
- comparing said calculated change amount with a predetermined limit value;
- permitting an abnormality diagnosis of said variable valve timing apparatus on a condition that said change amount has been kept equal to or less than said predetermined limit value for a predetermined period by said comparison;
- and
- diagnosing an abnormality of said variable valve timing apparatus when said abnormality diagnosis is permitted.
Dependencies are inferred from the claim text.