Method and system for variable displacement engine diagnostics

Patent metadata

Field	Value
Publication number	US-10801418-B2
Application number	US-201815963893-A
Country	US
Kind code	B2
Filing date	Apr 26, 2018
Priority date	Apr 26, 2018
Publication date	Oct 13, 2020
Grant date	Oct 13, 2020

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.

First claim

The invention claimed is:

1. A method for an engine, comprising:
actuating, via a solenoid, an electronic latch pin of a cylinder valve deactivation mechanism coupled to a cam-actuated cylinder valve;
estimating camshaft timing based on inferred latch pin movement during the actuating; and
estimating a crankshaft position based on the inferred latch pin movement during the actuating, and wherein a timing of cylinder fuel injection is further adjusted based on the estimated crankshaft position.

2. The method of claim 1 , further comprising inferring latch pin movement based on an inductive current signature of the solenoid, the inductive current signature including one or more of a position of current peaks and valleys, and a slope of the inductive current signature.

3. The method of claim 1 , further comprising adjusting a timing of cylinder fuel injection based on the estimated camshaft timing.

4. The method of claim 1 , wherein the actuating includes energizing the solenoid to move the electronic latch pin from an engaged position to a disengaged position or from the disengaged position to the engaged position.

5. The method of claim 4 , wherein the cam-actuated cylinder valve is an exhaust valve of a cylinder, and wherein the solenoid is energized when a piston of the cylinder is in an upstroke.

6. The method of claim 5 , wherein the estimating camshaft timing includes:
indicating that the piston of the cylinder is in an exhaust stroke responsive to an absence of latch pin movement; and
indicating that the piston of the cylinder is in a compression stroke responsive to a presence of latch pin movement.

7. The method of claim 4 , wherein the cam-actuated cylinder valve is an intake valve of a cylinder, and wherein the solenoid is energized when a piston of the cylinder is in a downstroke.

8. The method of claim 7 , wherein the estimating includes:
indicating that the piston of the cylinder is in an intake stroke responsive to an absence of latch pin movement; and
indicating that the piston of the cylinder is in a power stroke responsive to a presence of latch pin movement.

9. The method of claim 1 , wherein the estimating the camshaft timing is further based on a crankshaft position sensed via a crankshaft position sensor.

10. A method for an engine, comprising:
energizing a solenoid of a cylinder valve deactivation mechanism coupled to a valve of a cylinder, the valve actuated by a cam;
inferring a stroke of the cylinder based on a current of the solenoid during the energizing; and
estimating a camshaft position based on the inferred stroke of the cylinder, wherein the estimating the camshaft position is further based on an engine crankshaft position retrieved from a crankshaft position sensor during a first condition, and wherein the inferred stroke of the cylinder is further used to determine the engine crankshaft position during a second condition.

11. The method of claim 10 , wherein the cylinder valve deactivation mechanism includes a latch pin, and energizing the solenoid moves the latch pin between an engaged position and a disengaged position when the cam is on base circle and not when the cam is lifted.

12. The method of claim 11 , wherein a presence of latch pin movement is inferred based on a presence of a local current minimum as the current increases to a maximum, and an absence of latch pin movement is inferred based on an absence of the local current minimum as the current increases to the maximum.

13. The method of claim 12 , wherein the valve is an exhaust valve, and inferring the stroke of the cylinder based on the current of the solenoid during the energizing includes inferring an exhaust stroke in response to an absence of latch pin movement.

14. The method of claim 12 , wherein the valve is an intake valve, and inferring the stroke of the cylinder based on the current of the solenoid during the energizing includes inferring an intake stroke in response to an absence of latch pin movement.

15. The method of claim 10 , further comprising, adjusting a timing of cylinder fuel injection based on the estimated camshaft position.

16. An engine system, comprising:
an engine cylinder including an intake valve and a fuel injector;
an intake cam mounted on an intake camshaft for opening and closing the intake valve;
a crankshaft;
an exhaust valve;
an exhaust camshaft;
a valve deactivation mechanism coupled to the intake valve, the valve deactivation mechanism including a rocker arm assembly and a latch pin, an inner arm of the rocker arm assembly coupled to the intake 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 selectively engages the outer arm via the latch pin;
an electric solenoid coupled to the latch pin; and
a controller with computer readable instructions stored in non-transitory memory that when executed cause the controller to:
energize the electric solenoid to actuate the latch pin;
measure an induction current generated by the electric solenoid upon energization;
infer movement of the latch pin upon energization based on the measured induction current;
estimate an intake camshaft position based on the inferred movement;
adjust a pulse-width commanded to the fuel injector based on the estimated intake camshaft position;
estimate a crankshaft position based on two or more of the inferred movement, output from a crankshaft position sensor coupled to the crankshaft, and output from a camshaft position sensor coupled to the intake camshaft;
update the intake camshaft position based on the estimated crankshaft position; and
estimate an exhaust camshaft position of the exhaust camshaft based on the estimated intake camshaft position.

17. The system of claim 16 , wherein the controller estimating the intake camshaft position based on the inferred movement includes:
indicating that a piston of the engine cylinder is in an intake stroke responsive to an absence of inferred latch pin movement; and
indicating that the piston of the engine cylinder is in a compression, power, or exhaust stroke responsive to a presence of inferred latch pin movement.

Assignees

• Ford Global Tech Llc

Inventors

• Mcconville Gregory
• Ulrey Joseph
• Karnik Amey

Classifications

• F01L2001/186

  Split rocking arms, e.g. rocker arms having two articulated parts and means for varying the relative position of these parts or for selectively connecting the parts to move in unison · CPC title

• F01L2800/01

  Starting · CPC title

• F02D2041/0012

  with selective deactivation of cylinders · CPC title

• F01L2305/00

  Valve arrangements comprising rollers · CPC title

• F02B77/08

  Safety, indicating, or supervising devices (thermal insulation F02B77/11; monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00) · CPC title