System and method for detecting stochastic pre-ignition
View Patent ↗A system according to the principles of the present disclosure includes a vibration intensity module and a stochastic pre-ignition (SPI) detection module. The vibration intensity module determines a vibration intensity of an engine over a first engine cycle and a second engine cycle. The first engine cycle and the second engine cycle each correspond to a predetermined amount of crankshaft rotation. The SPI detection module selectively detects stochastic pre-ignition when the vibration intensity of the first engine cycle is less than a first threshold and the vibration intensity of the second engine cycle is greater than a second threshold.
1. A system comprising:
a vibration intensity module that determines a vibration intensity of an engine over a first engine cycle and a second engine cycle, wherein the first engine cycle and the second engine cycle each correspond to a predetermined amount of crankshaft rotation; and
a stochastic pre-ignition (SPI) detection module that selectively detects stochastic pre-ignition when the vibration intensity of the first engine cycle is less than a first threshold and the vibration intensity of the second engine cycle is greater than a second threshold.
2. The system of claim 1 wherein:
the vibration intensity module determines the vibration intensity of the engine over a third engine cycle and a fourth engine cycle, wherein the third engine cycle and the fourth engine cycle each correspond to the predetermined amount of crankshaft rotation; and
the SPI detection module detects stochastic pre-ignition when the vibration intensity of the third engine cycle is less than the first threshold and the vibration intensity of the fourth engine cycle is greater than the second threshold.
3. The system of claim 2 wherein the first engine cycle, the second engine cycle, the third engine cycle, and the fourth engine cycle are consecutive engine cycles.
4. The system of claim 2 wherein the second threshold is greater than the first threshold.
5. The system of claim 4 wherein:
the SPI detection module detects stochastic pre-ignition when the vibration intensity is greater than a third threshold; and
the third threshold is greater than the second threshold.
6. The system of claim 5 wherein the SPI detection module determines the first threshold, the second threshold, and the third threshold based on engine speed and engine knock.
7. The system of claim 1 wherein the vibration intensity module determines the vibration intensity based on input received from a vibration sensor.
8. The system of claim 7 wherein the vibration intensity module:
generates a spectral density for each cylinder of the engine;
sums the spectral densities of each cylinder in the engine to yield a spectral density for the engine cycle; and
determines the vibration intensity based on the spectral density for the engine cycle.
9. The system of claim 8 wherein the vibration intensity module generates a spectral density for each cylinder of the engine based on the vibration sensor input during a predetermined range of crankshaft rotation.
10. The system of claim 1 further comprising a boost control module that reduces boost in the engine when stochastic pre-ignition is detected.
11. A method comprising:
determining a vibration intensity of an engine over a first engine cycle and a second engine cycle, wherein the first engine cycle and the second engine cycle each correspond to a predetermined amount of crankshaft rotation; and
selectively detecting stochastic pre-ignition when the vibration intensity of the first engine cycle is less than a first threshold and the vibration intensity of the second engine cycle is greater than a second threshold.
12. The method of claim 11 further comprising:
determining the vibration intensity of the engine over a third engine cycle and a fourth engine cycle, wherein the third engine cycle and the fourth engine cycle each correspond to the predetermined amount of crankshaft rotation; and
detecting stochastic pre-ignition when the vibration intensity of the third engine cycle is less than the first threshold and the vibration intensity of the fourth engine cycle is greater than the second threshold.
13. The method of claim 12 wherein the first engine cycle, the second engine cycle, the third engine cycle, and the fourth engine cycle are consecutive engine cycles.
14. The method of claim 12 wherein the second threshold is greater than the first threshold.
15. The method of claim 14 further comprising detecting stochastic pre-ignition when the vibration intensity is greater than a third threshold, wherein the third threshold is greater than the second threshold.
16. The method of claim 15 further comprising determining the first threshold, the second threshold, and the third threshold based on engine speed and engine knock.
17. The method of claim 11 further comprising determining the vibration intensity based on input received from a vibration sensor.
18. The method of claim 17 further comprising:
generating a spectral density for each cylinder of the engine;
summing the spectral densities of each cylinder in the engine to yield a spectral density for the engine cycle; and
determining the vibration intensity based on the spectral density for the engine cycle.
19. The method of claim 18 further comprising generating a spectral density for each cylinder of the engine based on the vibration sensor input during a predetermined range of crankshaft rotation.
20. The method of claim 11 further comprising reducing boost in the engine when stochastic pre-ignition is detected.