Response amplitude modification for hybrid electric vehicle misfire detections

Patent metadata

Field	Value
Publication number	US-10005469-B2
Application number	US-201615176379-A
Country	US
Kind code	B2
Filing date	Jun 8, 2016
Priority date	Jun 8, 2016
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

Misfire detection techniques for a hybrid electric vehicle (HEV) including an internal combustion engine and an electric motor involve utilizing a crankshaft speed sensor configured to generate a crankshaft speed signal indicative of a rotational speed of a crankshaft of the engine that is coupled to the electric motor via a flywheel. The techniques also utilize a controller configured to control the electric motor to provide a vibrational response to dampen disturbances to the crankshaft, receive the crankshaft speed signal, selectively modify the crankshaft speed signal to obtain a modified crankshaft speed signal, and detect a misfire of the engine based on the modified crankshaft speed signal and a set of thresholds including at least one of a negative misfire threshold and a positive vibrational response threshold.

First claim

What is claimed is:

1. A misfire detection system for a hybrid electric vehicle (HEV) including an internal combustion engine and an electric motor, the system comprising:
a crankshaft speed sensor configured to generate a crankshaft speed signal indicative of a rotational speed of a crankshaft of the engine, the crankshaft being coupled to the electric motor via a flywheel; and
a controller configured to:
control the electric motor to provide a vibrational response to dampen disturbances to the crankshaft;
receive the crankshaft speed signal;
modify an amplitude of the crankshaft speed signal to obtain a modified crankshaft speed signal; and
detect a misfire of the engine based on the modified crankshaft speed signal and a set of thresholds, wherein the set of thresholds includes at least one of a negative misfire threshold and a positive vibrational response threshold.

2. The system of claim 1 , wherein the controller is further configured to selectively modify, as a product with a vibrational decay coefficient, an amplitude of each of one or more peaks of the crankshaft speed signal corresponding to firing events of the engine.

3. The system of claim 1 , wherein the controller is further configured to detect the misfire of the engine by monitoring N consecutive firing events of the engine, wherein N is an integer greater than one and is calibrated for a particular engine load and engine speed.

4. The system of claim 3 , wherein the controller is further configured to:
detect a first misfire of the engine when (i) a first negative peak of the crankshaft speed signal corresponding to a first firing event of the N consecutive firing events is less than (ii) the negative misfire threshold; and
after detecting the first misfire, detect a potential second misfire of the engine when (i) a subsequent second peak of the crankshaft speed signal corresponding to a second firing event of the N consecutive firing events is less than (ii) the positive vibrational response threshold.

5. The system of claim 4 , wherein the controller is further configured to:
after detecting the potential second misfire of the engine, detect the second misfire of the engine when (i) the second peak of the crankshaft speed signal is less than (ii) a predetermined negative misfire threshold; and
when no second misfire is detected, apply amplitude adjustments to subsequent peaks of the crankshaft speed signal corresponding to a remainder of the N consecutive firing events.

6. The system of claim 4 , wherein:
when the second peak does exceed the vibrational response threshold, the controller is configured to modify the crankshaft speed signal by reducing the second peak as a product with a vibrational decay coefficient to obtain the modified crankshaft speed signal that includes a modified second peak; and
the controller is further configured to detect the second misfire based on a magnitude of the modified second peak.

7. The system of claim 3 , wherein:
the controller is configured to detect a first misfire of the engine when (i) a magnitude of a first peak of the crankshaft speed signal corresponding to a first firing event of the N consecutive firing events exceeds (ii) the misfire threshold;
after detecting the first misfire, the controller is configured to modify the crankshaft speed signal by applying amplitude adjustments to (N−1) next peaks of the crankshaft speed signal corresponding to a remainder of the N consecutive firing events, wherein each amplitude adjustment is calculated as a minimum of an original amplitude and an absolute value of the difference between the original amplitude and a product of corresponding base and coefficient values retrieved from separate look-up tables, and wherein the base coefficient values are determined by modeling the vibrational response based on engine speed and engine load; and
the controller is configured to detect one or more additional misfires of the engine based on magnitudes of the (N−1) modified peaks.

8. The system of claim 7 , wherein the controller is further configured to continuously update at least one of amplitude, damping, and frequency of the modeled vibrational response during a deceleration fuel cutoff (DFCO) event.

9. The system of claim 3 , wherein:
the controller is configured to detect a vibrational response when (i) a magnitude of a first peak of the crankshaft speed signal corresponding to a first firing event of the N consecutive firing events exceeds (ii) the vibrational response threshold;
after detecting the vibrational response, the controller is configured to modify the crankshaft speed signal by modifying the first peak and (N−1) next peaks of the crankshaft speed signal each as a product with a corresponding vibrational decay coefficient to obtain N modified peaks of the modified crankshaft speed signal, wherein the (N−1) next peaks correspond to a remainder of the N consecutive firing events; and
the controller is configured to detect one or more misfires of the engine based on magnitudes of the N modified peaks.

10. The system of claim 1 , wherein the flywheel is a dual-mass flywheel that provides another vibrational response to dampen the disturbances to the crankshaft.

11. A misfire detection method for a hybrid electric vehicle (HEV) comprising an internal combustion engine and an electric motor, the method comprising:
controlling, by a controller of the HEV, the electric motor to provide a vibrational response to dampen disturbances to a crankshaft of the engine, the crankshaft being coupled to the electric motor via a flywheel;
receiving, by the controller and from a crankshaft sensor of the HEV, a crankshaft speed signal indicative of a rotational speed of the crankshaft;
selectively modifying, by the controller, an amplitude of the crankshaft speed signal to obtain a modified crankshaft speed signal; and
detecting, by the controller, a misfire of the engine based on the modified crankshaft speed signal and a set of thresholds, wherein the set of thresholds includes at least one of a negative misfire threshold and a positive vibrational response threshold.

12. The method of claim 11 , further comprising selectively modifying, by the controller and as a product with a vibrational decay coefficient, an amplitude of each of one or more peaks of the crankshaft speed signal corresponding to firing events of the engine.

13. The method of claim 11 , further comprising detecting, by the controller, the misfire of the engine by monitoring N consecutive firing events of the engine, wherein N is an integer greater than one and is calibrated for a particular engine load and engine speed.

14. The method of claim 13 , further comprising:
detecting, by the controller, a first misfire of the engine when (i) a first negative peak of the crankshaft speed signal corresponding to a first firing event of the N consecutive firing events is less than (ii) the negative misfire threshold; and
after detecting the first misfire, detecting, by the controller, a potential second misfire of the engine when (i) a subsequent second peak of the crankshaft speed signal corresponding to a second firing event of the N consecutive firing events is less than (ii) the positive vibrational response threshold.

15. The method of claim 14 , further comprising:
after detecting the potential second misfire of the engine, detecting, by the controller, the second misfire of the engine when (i) the second peak of the crankshaft speed signal is less than (ii) a predetermined misfire threshold; and
when no second misfire is detected, applying, by the controller, amplitude adjustment

Assignees

• Guo Yichao
• Stack Robert
• Wu Gang
• Quiles Marcio
• Fca Us Llc

Inventors

• Guo Yichao
• Stack Robert
• Wu Gang
• Quiles Marcio

Classifications

• F02D41/1498

  measuring engine roughness · CPC title

• B60W30/20 Primary

  Reducing vibrations in the driveline · CPC title

• F02D2200/1015

  Engines misfires · CPC title

• B60W2030/206

  related or induced by the engine · CPC title

• B60W2510/0638

  Engine speed · CPC title