Methods and systems for diagnosing non-deactivated valves of disabled engine cylinders

Patent metadata

Field	Value
Publication number	US-11560859-B1
Application number	US-202217648908-A
Country	US
Kind code	B1
Filing date	Jan 25, 2022
Priority date	Jan 25, 2022
Publication date	Jan 24, 2023
Grant date	Jan 24, 2023

Abstract

Methods and systems are provided for a diagnostic routine of a variable displacement engine (VDE) of a vehicle to detect non-deactivated valves of deactivated cylinders due to a degraded valve deactivation mechanism. In one example, a method comprises, during operation of the VDE with one or more cylinders of the VDE deactivated, calculating a variation in a fast-sampled signal outputted by one or more exhaust gas oxygen (EGO) sensors of the VDE over a plurality of engine cycles; determining that the variation is greater than the threshold variation; and in response, indicating that valves of the one or more cylinders are not deactivated. A second method comprises estimating a throttle air flow rate and an engine air flow rate of the VDE; and indicating non-deactivated valves of one or more deactivated cylinders if the throttle air flow rate exceeds the engine air flow rate by a threshold.

First claim

The invention claimed is:

1. A method for a controller of a variable displacement engine (VDE), comprising:
during operation of the VDE with one or more cylinders of the VDE deactivated:
calculating a variation in a fast-sampled signal outputted by one or more exhaust gas oxygen (EGO) sensors of the VDE over a plurality of engine cycles;
determining that the variation is greater than the threshold variation, and in response, indicating that at least one intake valve and at least one exhaust valve of the one or more cylinders are not deactivated,
wherein calculating the variation in the fast-sampled signal includes:
sampling a signal of an EGO sensor of the one or more EGO sensors at a rate at least twice a firing rate of activated cylinders sharing the EGO sensor;
collecting signal samples spanning one engine cycle in a first-in-first-out (FIFO) buffer, and at least one of:
performing a statistical operation on the samples to generate a de-trended signal, and rectifying the de-trended signal by one of averaging and summing an absolute value of the de-trended signal over a predetermined number of engine cycles to generate a measurement of the variation;
calculating a standard deviation of the samples;
calculating an amplitude or a peak-to-peak amplitude of the samples;
taking an absolute value of a derivative of the samples; and
calculating a magnitude of frequency components of the samples at engine-cycle frequency or an integer multiple of engine-cycle frequency.

2. The method of claim 1 , wherein performing the statistical operation on the samples includes one of:
subtracting a median signal of the samples from the middle buffer element;
subtracting a mean signal of the samples from the middle buffer element.

3. The method of claim 1 , wherein the threshold variation is calculated by:
estimating a baseline variation, based on a nominal expected AFR imbalance in a VDE where all intake and exhaust valves of all deactivated cylinders are deactivated, averaged over a plurality of engine cycles;
estimating a highest probable air fuel ratio (AFR) imbalance variation, the highest probable AFR imbalance variation an average of the variations in the signals outputted by the one or more EGO sensors of the VDE under a highest probable rich AFR imbalance condition and/or a highest probable lean AFR imbalance condition, over a plurality of engine cycles;
estimating a non-deactivated valve variation, the non-deactivated valve variation an average of the variations in the signals outputted by the one or more EGO sensors of the VDE under a condition where at least one intake valve and at least one exhaust valve of the one or more deactivated cylinders are not deactivated, over a plurality of engine cycles; and
establishing the threshold variation higher than the baseline variation and higher than the highest probable AFR imbalance variation, but lower than the non-deactivated valve variation.

4. The method of claim 3 , wherein the highest probable rich AFR imbalance condition is a 35% rich imbalance, and the highest probable lean AFR imbalance condition is a 35% lean imbalance.

5. The method of claim 1 , wherein the one or more EGO sensors include a universal exhaust gas oxygen (UEGO) sensor.

6. The method of claim 1 , further comprising:
in response to the variation being greater than a threshold variation, adjusting an operation of the VDE to selectively activate all or different cylinders of the VDE.

7. The method of claim 1 , further comprising:
in a first condition, where the variation in the signal outputted by the one or more EGO sensors is greater than a threshold variation, indicating that valves of one or more cylinders of the VDE are not deactivated; and
in a second condition, where the variation in the signal outputted by the one or more EGO sensors is not greater than a threshold variation, not indicating that valves of the one or more cylinders of the VDE are not deactivated.

8. A method for a controller of a variable displacement engine (VDE), comprising:
during a steady-state or quasi-steady operation of the VDE with one or more cylinders of the VDE deactivated, where the one or more cylinders of the VDE being deactivated includes the intake valve and the exhaust valve being commanded to be held in a closed position, estimating a throttle air flow rate and an engine air flow rate of the VDE; and
in response to the estimated throttle air flow rate exceeding the estimated engine air flow rate by a threshold, indicating that an intake valve and an exhaust valve of at least one of the one or more deactivated cylinders is not being held in a closed position.

9. The method of claim 8 , wherein the threshold is a threshold percentage.

10. The method of claim 8 , further comprising estimating the throttle flow rate based on at least one of an opening of a throttle of the VDE, a throttle inlet pressure (TIP), a throttle inlet temperature, and a pressure drop across the throttle.

11. The method of claim 10 , wherein the pressure drop across the throttle is measured using a differential pressure sensor.

12. The method of claim 10 , wherein the pressure drop across the throttle is calculated by subtracting an intake manifold absolute pressure (MAP) from the TIP.

13. The method of claim 8 , further comprising estimating the throttle flow rate based on an output of a mass air flow (MAF) sensor of the VDE.

14. The method of claim 8 , wherein estimating the engine flow rate includes multiplying an individual cylinder flow rate by a number of inducting cylinders of the VDE corresponding to a condition with no VDE malfunction, the individual cylinder flow rate estimated based on at least one of the intake MAP, an intake manifold charge temperature (MCT), an engine speed, an intake valve timing, and an exhaust valve timing.

15. The method of claim 8 , wherein indicating non-deactivated valves of one or more deactivated cylinders if the throttle air flow rate exceeds the engine air flow rate by a threshold further comprises indicating non-deactivated valves of a plurality of deactivated cylinders based on whether the throttle air flow rate exceeds the engine air flow rate by a respective plurality of thresholds.

16. A system for controlling a variable displacement engine (VDE) of a vehicle, comprising:
a controller with computer readable instructions stored on non-transitory memory that when executed during operation of the VDE, cause the controller to:
during operation of the VDE with one or more cylinders of the VDE deactivated:
execute a diagnostic routine to determine whether valves of one or more deactivated cylinders have not been deactivated, the diagnostic routine comprising at least one of:
calculating a variation in a fast-sampled signal outputted by the one or more EGO sensors over a plurality of engine cycles, and in response to the variation being greater than a threshold variation, indicating non-deactivated valves of the one or more deactivated cylinders; and
estimating a throttle air flow rate and an engine air flow rate of the VDE, and indicating non-deactivated valves of the one or more deactivated cylinders if the throttle air flow rate exceeds the engine air flow rate by a threshold; and

in response to an indication of non-deactivated valves of the one or more deactivated cylinders, activate the one or more deactivated cylinders, set a malfunction indicator light (MIL), and/or adjust the operation of the VDE.

17. The system of claim 16 , wherein calculating the variation in the fast-sampled signal further comprises:
collecting signal sa

Assignees

• Ford Global Tech Llc

Inventors

• Kiwan Rani
• Krach Adam
• Hughes Scott Richard
• Shimon Richard
• Grant Kathleen
• Wyman David

Classifications

• F02D2200/0406

  Intake manifold pressure · CPC title

• F02D2200/0414

  Air temperature · CPC title

• F02D41/008 Primary

  Controlling each cylinder individually · CPC title

• F02D13/06 Primary

  Cutting-out cylinders · CPC title

• F02D41/0087

  Selective cylinder activation, i.e. partial cylinder operation (deceleration cut-off F02D41/123) · CPC title