METHOD AND SYSTEM FOR VARIABLE DISPLACEMENT ENGINE DIAGNOSTICS
First Claim
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1. A method for an engine, comprising:
- actuating, via a solenoid, an electric latch pin of a cylinder valve deactivation mechanism coupled to a valve of a cylinder at a first time while engine speed is less than a threshold; and
indicating degradation of the cylinder valve deactivation mechanism based on inferred latch pin movement during the actuating.
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Abstract
Methods and systems are provided for diagnosing a cylinder valve deactivation mechanism in an engine system having cam-actuated valves. Movement of a latch pin of the deactivation mechanism is inferred from an induction current generated by a solenoid coupled to the latch pin, and the inferred movement is used to diagnose operation of cylinder valve deactivation mechanism. The inferred movement and a profile of the induction current is also used to estimate camshaft and crankshaft timing for improved cylinder fuel delivery in the absence of a camshaft sensor.
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Citations
20 Claims
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1. A method for an engine, comprising:
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actuating, via a solenoid, an electric latch pin of a cylinder valve deactivation mechanism coupled to a valve of a cylinder at a first time while engine speed is less than a threshold; and indicating degradation of the cylinder valve deactivation mechanism based on inferred latch pin movement during the actuating. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for an engine, comprising:
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after starting an engine, while engine speed is at or below an idling speed and independent of engine load, diagnosing a valve deactivation mechanism coupled to a cylinder valve based on latch pin movement, the movement inferred while electrically actuating the latch pin; and after the diagnosing, electrically actuating the latch pin to selectively operate the valve deactivation mechanism based on the engine load. - View Dependent Claims (14, 15, 16, 17)
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18. An engine system, comprising:
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an engine cylinder including an intake valve; a cam mounted on a camshaft for opening and closing the intake valve; a valve deactivation mechanism coupled to the intake valve, the mechanism including a rocker arm assembly and a latch pin, an inner arm of the rocker arm assembly coupled to the cam via a cam follower and coupled to a stem of the intake valve, an outer arm of the rocker arm assembly coupled to the latch pin, the inner arm engagable to the outer arm via the latch pin; an electric solenoid coupled to the latch pin; an engine speed sensor; and a controller with computer readable instructions that when executed cause the controller to; after starting the engine, while engine speed is below a threshold, and independent of engine load over a drive cycle, energize the solenoid to actuate the latch pin from a latched position where the inner arm is engaged to the outer arm via the latch pin, and where the intake valve can lift via concerted movement of the outer arm and inner arm of the rocker arm assembly, to an unlatched position where the inner arm is disengaged from the outer arm and the intake valve cannot be lifted; measure an induction current generated by the solenoid upon energization; infer presence or absence of movement of the latch pin between the latched position and the unlatched position upon the energization based on the measured induction current; and indicate degradation of the valve deactivation mechanism responsive to the inferred presence or absence of movement of the latch pin relative to an expected movement, the expected movement based on cam timing. - View Dependent Claims (19, 20)
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Specification