Engine System and Method

• US 20160160776A1
• Filed: 12/08/2014
• Published: 06/09/2016
• Est. Priority Date: 12/08/2014
• Status: Abandoned Application

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: YEAGER, Mary L., Clark, Francis L., Gregory, Brandon
• Application Number:
  US14/563,337
• Publication Number:
  US 20160160776A1
• Time in Patent Office: Days
• CPC Class Codes: F02D 2041/228 Warning displays
• CPC Class Codes: F02D 2200/1015 Engines misfires
• CPC Class Codes: F02D 35/023 by determining the cylinder pressure
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02D 35/028 by determining the combustion timing or phasing
• CPC Class Codes: F02D 41/009 using means for generating position or synchronisation signals
• CPC Class Codes: F02D 41/22 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 Class Codes: F02P 5/152 dependent on pinking detecting or indicating knocks in internal-combustion engines G01L23/22

Abstract

A pressure sensor disposed to sense an engine cylinder pressure provides a pressure signal, and an engine timing sensor provides an engine timing signal to an electronic controller, which is programmed to receive and analyze the pressure and engine timing signals to determine a misfire signal, a peak pressure signal, a pressure rise rate, an actual ignition signal, and a center of combustion signal. The electronic controller is further programmed to activate a fault flag when at least one of the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, and the center of combustion signal, indicates that an abnormal combustion is present in the cylinder.

Claims

1. An engine, comprising:

a cylinder having cylinder bore formed in a cylinder block;

a piston reciprocally disposed within the cylinder bore;

a crankshaft connected to the piston such that reciprocal motion of the piston will result in rotational motion of the crankshaft;

one or more piston ring seals connected to the piston and disposed between the piston and the cylinder bore to sealably and slidingly engage the cylinder bore, and a cylinder head disposed to block an open end of the cylinder bore such that a combustion chamber is defined within the cylinder bore between the piston and the cylinder head;

a pressure sensor disposed to sense a cylinder pressure within the combustion chamber and provide a pressure signal, which is indicative of the cylinder pressure;

an engine timing sensor disposed to sense an angle of a rotating component of the engine and provide an engine timing signal, which is indicative of a position of the piston within the cylinder bore; and

an electronic controller programmed to;

receive the pressure signal from the pressure sensor;

receive the engine timing signal from the engine timing sensor;

analyze the pressure signal and the engine timing signal to determine at least one of a misfire signal, a peak pressure signal, a pressure rise rate, an actual ignition signal, and a center of combustion signal; and

activate a fault flag when the at least one of the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, and the center of combustion signal, indicates that an abnormal combustion is present in the cylinder.

2. The engine of claim 1, further comprising a fuel injector disposed to inject fuel into the cylinder in response to an injection command signal provided by the electronic controller to the fuel injector, the injection command signal being associated with a particular engine timing that is expected to produce an ignition of the fuel at an ignition time, wherein at least the center of combustion signal further depends on the injection command signal.

3. The engine of claim 1, wherein determining the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, and the center of combustion signal, further depends on an engine speed signal and an engine load signal.

4. The engine of claim 3, wherein the electronic controller further includes therein a table, which includes tabulated values of expected parameters for each of the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, and the center of combustion signal for a given engine speed and engine load, and wherein the table provides a particular expected value corresponding to each signal.

5. The engine of claim 4, wherein the electronic controller is further configured to calculate a difference between each of the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, the center of combustion signal, and a corresponding particular expected value for each, to yield a corresponding difference, and further compares the corresponding difference with a corresponding threshold value.

6. The engine of claim 5, wherein the fault flag is activated when the corresponding difference exceeds the corresponding threshold value.

7. The engine of claim 1, wherein the misfire signal is determined in a detonation determinator within the electronic controller, the detonation determinator including a comparator function that compares the pressure signal with a pressure band that comprises a lower cylinder pressurization threshold pressure and an upper pressure value such that, when the pressure signal indicates that the cylinder is pressurized, the detonation determinator may determine that a misfire is present and provide the misfire signal.

8. The engine of claim 1, wherein the peak pressure signal is determined in a peak pressure determinator, the peak pressure determinator including a comparator function that compares a maximum cylinder pressure reached in the cylinder, as indicated by the pressure signal, with a peak cylinder pressure threshold such that, when the pressure signal indicates that the maximum cylinder pressure reached in the cylinder is outside of an acceptable band of peak pressures, the peak pressure determinator provides the peak pressure signal, which indicates that the abnormal combustion may be occurring which generates peak pressures in the cylinder that are too high or too low.

9. The engine of claim 1, wherein the pressure rise rate is determined in a pressure rise determinator, which calculates a parameter related to a derivative of an increase in the pressure signal with respect to the angle, as indicated by the engine timing signal, in a form of ∂

P/∂

α

, where P indicates the cylinder pressure and α

indicates the angle.

10. The engine of claim 1, wherein the actual ignition signal is determined in a combustion initiation determinator, which receives at least the pressure signal and the engine timing signal, and wherein the combustion initiation determinator operates to continuously compare the cylinder pressure with a then-present engine timing to determine a sharp rise in the cylinder pressure, which is indicative of a burn initiation or ignition of fuel within the cylinder.

11. The engine of claim 1, wherein the center of combustion signal is determined in a center of combustion determinator, which, based on the pressure signal, the engine timing signal, and an ignition timing signal, determines a median angle of combustion over a combustion range or duration in the engine, and provides the center of combustion signal.

12. The engine of claim 1, further comprising a plurality of cylinders, each of the plurality of cylinders including a corresponding pressure sensor such that the electronic controller receives and analyzes a plurality of pressure signals, wherein the electronic controller is further configured to activate a corresponding fault flag with respect to each of the plurality of cylinders separately during normal engine operation.

13. A method for diagnosing an abnormal combustion in a cylinder of an engine, comprising:

monitoring a pressure signal from an engine pressure sensor, which is indicative of a fluid pressure within a combustion chamber of the engine;

monitoring an engine timing signal from an engine timing sensor, which is indicative of a rotation of an output shaft of the engine and also indicative of a position of a piston within the cylinder;

receiving the pressure signal from the engine pressure sensor in an electronic controller;

receiving the engine timing signal from the engine timing sensor in the electronic controller;

analyzing the pressure signal and the engine timing signal using the electronic controller during normal engine operation to determine, in real time, at least one of a misfire signal, a peak pressure signal, a pressure rise rate, an actual ignition signal, and a center of combustion signal; and

activating a fault flag in the electronic controller when at least one of the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, and the center of combustion signal, indicates that the abnormal combustion is present in the cylinder.

14. The method of claim 13, further comprising injecting fuel into the cylinder using a fuel injector and in response to an injection command signal provided by the electronic controller to the fuel injector, wherein the injection command signal is associated with a particular timing of the engine that is expected to produce an ignition of fuel at an ignition time, and wherein determining at least the center of combustion signal further depends on the injection command signal.

15. The method of claim 13, wherein determining the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, and the center of combustion signal, further depends on an engine speed signal and an engine load signal that are monitored by the electronic controller.

16. The method of claim 15, further comprising storing a table in the electronic controller, the table including tabulated values of expected parameters for each of the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, and the center of combustion signal for a given engine speed and engine load, and providing, based on the table, a particular expected value corresponding to each signal.

17. The method of claim 16, further comprising:

calculating, using the electronic controller, a difference between each of the misfire signal, the peak pressure signal, the pressure rise rate, the actual ignition signal, the center of combustion signal, and a corresponding particular expected value for each, to yield a corresponding difference; and

comparing the corresponding difference with a corresponding threshold value.

18. The method of claim 17, wherein activating the fault flag is accomplished when the corresponding difference exceeds the corresponding threshold value.

19. The method of claim 13, wherein the engine further comprises a plurality of cylinders, each of the plurality of cylinders including a corresponding pressure sensor such that the electronic controller receives and analyzes a plurality of pressure signals, wherein the electronic controller is further configured to activate a corresponding fault flag with respect to each of the plurality of cylinders separately during normal engine operation.

20. The method of claim 13, wherein, at least one of:

the misfire signal is determined in a detonation determinator within the electronic controller, the detonation determinator including a comparator function that compares the pressure signal with a pressure band that comprises a lower cylinder pressurization threshold pressure and an upper pressure value such that, when the pressure signal indicates that the cylinder is pressurized, the detonation determinator may determine that a misfire is present and provide the misfire signal;

the peak pressure signal is determined in a peak pressure determinator, the peak pressure determinator including an additional comparator function that compares a maximum cylinder pressure reached in the cylinder, as indicated by the pressure signal, with a peak cylinder pressure threshold such that, when the pressure signal indicates that the maximum cylinder pressure reached in the cylinder is outside of an acceptable band of peak pressures, the peak pressure determinator provides the peak pressure signal, which indicates that the abnormal combustion may be occurring which generates peak pressures in the cylinder that are too high or too low;

the pressure rise rate is determined in a pressure rise determinator, which calculates a parameter related to a derivative of an increase in the pressure signal with respect to crank angle, as indicated by the engine timing signal, in a form of ∂

P/∂

α

, where P indicates a cylinder pressure and α

indicates the angle;

the actual ignition signal is determined in a combustion initiation determinator, which receives at least the pressure signal and the engine timing signal, and wherein the combustion initiation determinator operates to continuously compare the cylinder pressure with a then-present engine timing to determine a sharp rise in the cylinder pressure, which is indicative of a burn initiation or ignition of fuel within the cylinder; and

the center of combustion signal is determined in a center of combustion determinator, which, based on the pressure signal, the engine timing signal, and an ignition timing signal, determines a median angle of combustion over a combustion range or duration in the engine, and provides the center of combustion signal.