Valve fault detection

Patent metadata

Field	Value
Publication number	US-9562470-B2
Application number	US-201514700494-A
Country	US
Kind code	B2
Filing date	Apr 30, 2015
Priority date	Mar 15, 2013
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

Methods and systems are described for detecting valve actuation faults in internal combustion engines operating in a skip fire operational mode. In one aspect, a torque model is used to estimate an expected net torque during a selected operating window. The torque model considers an expected torque contribution from each of the cylinders and accounts for the effects of specific skip fire firing decisions that affect the expected torque contribution from each cylinder. A parameter indicative of the actual engine torque is also measured. Valve actuation faults can then be identified based at least in part on a comparison of the measured parameter to an expected parameter value that is based at least in part on the expected net torque. With the described approaches, the occurrence of the valve actuation fault can be made within one engine cycle of the initial occurrence of the fault.

First claim

What is claimed is:

1. A method comprising:
operating an engine having a plurality of cylinders in a skip fire mode, the engine including at least one cylinder, each cylinder having at least one associated intake valve and one associated exhaust valve;
estimating an expected net torque during a selected operating window utilizing a torque model, wherein the torque model considers an expected torque contribution from each of the cylinders and accounts for the effects of specific skip fire firing decisions that affect the expected torque contribution from each cylinder during the selected operating window;
directly or indirectly measuring a parameter indicative of actual engine torque during the selected operating window;
determining whether a valve actuation fault has occurred based at least in part on a comparison of the measured parameter to an expected parameter value that is based at least in part on the expected net torque, wherein the determination is made within one engine cycle of the occurrence of the valve actuation fault; and
when it is determined that a valve actuation fault has occurred, performing at least one of (a) altering an aspect of control of the engine while the engine is operating in the skip fire mode in response to said determination; and (b) recording the detection of the valve actuation fault in a diagnostics system.

2. A method as recited in claim 1 wherein:
the valve actuation fault is determined to have occurred when the measured parameter exceeds the expected parameter by at least a threshold amount; and
the threshold varies based at least in part on a fire/skip status of one or more cylinders not associated with a valve being evaluated for the valve actuation fault.

3. A method as recited in claim 1 wherein:
the valve actuation fault is determined to have occurred when the measured parameter exceeds the expected parameter by at least a threshold amount; and
the threshold varies based at least in part on one or more selected engine operating conditions.

4. A method as recited in claim 3 wherein the engine operating conditions are selected from the group consisting of engine speed, intake manifold pressure, mass air charge, spark timing, cam advance and accessory load.

5. A method as recited in claim 1 wherein the torque model is based on a cylinder pressure model that predicts the pressure in each fired cylinder and the pressure in each skipped cylinder.

6. A method as recited in claim 5 wherein the pressure model accounts for the pressure in selected skipped cylinders dropping below intake manifold pressure.

7. A method as recited in claim 1 wherein the expected net torque estimation and the parameter measurements are repeatedly updated as the selected operating window moves and the event determination is made at least on a firing opportunity by firing opportunity basis.

8. A method as recited in claim 1 wherein the measured parameter is crankshaft acceleration and the expected parameter is a model crankshaft acceleration.

9. A method as recited in claim 8 further comprising applying a high pass filter to both the measured and model accelerations and wherein the event determination is made based on a comparison of the filtered measured and model accelerations.

10. A method as recited in claim 1 wherein the detected event is an intake valve actuation fault.

11. A method as recited in claim 1 wherein the detected event is an exhaust valve fault selected from the group consisting of an exhaust valve actuation timing fault and an exhaust valve lift error.

12. A method as recited in claim 1 wherein the determination of whether a valve actuation fault has occurred in based at least in part on an analysis of at least two selected operating windows, wherein a first one of the selected operating windows occurs during an exhaust stroke portion of a first working cycle and a second one of the operating windows occurs during an intake stroke portion of a skipped second working cycle that immediately follows the first working cycle.

13. A method as recited in claim 12 wherein the first selected operating window includes the portion of an exhaust stroke in which a piston reciprocating within the selected cylinder is in the range of 30 to 50 degrees prior to top dead center of the exhaust stroke.

14. A method as recited in claim 1 wherein the selected operating window includes a portion of an exhaust stroke in which a piston reciprocating within the selected cylinder is in the range of 30 to 50 degrees prior to top dead center of the exhaust stroke and the determination is made before the exhaust stroke is completed.

15. A method as recited in claim 1 wherein the parameter indicative of actual engine torque is a parameter indicative of crankshaft motion selected from the group consisting of crankshaft acceleration, crankshaft velocity and crankshaft jerk.

16. A method as recited in claim 1 wherein the parameter indicative of actual engine torque is a parameter indicative of crankshaft motion selected from the group consisting of:
differential crankshaft velocity; and
differential crankshaft acceleration.

17. A method comprising:
operating an engine having a plurality of cylinders in a skip fire mode;
estimating an expected net torque during a selected operating window utilizing a torque model, wherein the torque model considers an expected torque contribution from each of the cylinders and accounts for the effects of specific skip fire firing decisions that affect the expected torque contribution from each cylinder during the selected operating window;
directly or indirectly measuring a parameter indicative of actual engine torque during the selected operating window;
determining whether an exhaust valve actuation fault has occurred that caused an unexpected high pressure exhaust spring to occur in a selected cylinder based at least in part on a comparison of the measured parameter to an expected parameter value that is based at least in part on the expected net torque, wherein the determination is made within one engine cycle of the occurrence of the valve actuation fault; and
when it is determined that an unexpected high pressure exhaust spring has occurred, preventing an intake valve associated with the selected cylinder from opening into the unexpected high pressure exhaust spring.

18. A method as recited in claim 17 further comprising altering a skip fire firing sequence when it is determined that the high pressure exhaust spring is present in the selected cylinder, wherein the skip fire firing sequence is altered in response to the determination before a second working cycle that is the second following working cycle after the first working cycle begins.

19. A method as recited in claim 17 wherein the determination of whether a high pressure exhaust spring exists is further based at least in part on an analysis of an auxiliary monitor selected from the group consisting of:
a cylinder gas monitor arranged to detect an electrical property of gases within the selected cylinder using a spark plug;
a proximity sensor arranged to monitor movement of an exhaust valve associated with the selected cylinder;
an intake gas monitor;
an exhaust gas monitor; and
an engine block acceleration monitor.

20. A system for detecting the existence of a high pressure exhaust spring in an engine cylinder of an engine having at least one cylinder, the system comprising:
a processor and a computer readable media having programmed instructions for execution on the processor;
a torque

Assignees

• Tula Technology Inc

Inventors

• Younkins Matthew A
• Chen Shikui Kevin
• Chien Li-Chun
• Nagashima Masaki
• Parsels John W
• Routledge Geoff

Classifications

• G01P15/00

  Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration · CPC title

• F02D13/06

  Cutting-out cylinders · CPC title

• F02D35/023

  by determining the cylinder pressure · CPC title

• Y02T10/40

  Engine management systems · CPC title

• F02D41/22

  Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)} · CPC title