PSIG wrote: ↑Sun Sep 18, 2022 12:57 am
I would think you would want to look at both the trailing edge timing from #8 to #1, and the same timing from #1 to #2, for comparison as signature tooth. By eyeball it is about 25-30% difference, if you're comparing those, and not just a ±10% difference in the tooth width. In a way, it would be like missing-tooth, but in-reverse, and tighter tolerances (<30% instead of >50%) This will make sensed edge selection very important.
Of course, comparing both rising and falling edges would be nice. What approach are you thinking for this?
TFI_signature.jpg
Hey PSIG.
I've started my working out the expected crank angle for each rising and falling edge.
This calculation is based on the OEM Ford setup where the rising edge of the narrow tooth is 10 Deg BTDC.
What I'm planning to do is have the narrow signature tooth/gap be the second tooth in my series.
So in theory full sync is possible with less than 1 full revolution, this remains to be tested.
Also, as the sensor in this situation can only be hall effect, I can trigger on change of tooth edge.
So all 16 edges will update the internal calculation.
Giving a theoretical maximum of 55 Deg (Large tooth gap) without a reference signal, which is much better than 90, if using just one edge.
For now, I'm working on it being a hall sensor with nothing inline to invert it.
So the user can not change the edge.
Code: Select all // 7 even teeth & gaps, 1 narrow tooth & longer gap
// narrow tooth starts 10 deg BTDC
// Runs at cam speed, so 720 degrees and sequential
// Normal tooth length = 48 Deg
// Normal tooth gap = 42 Deg
// Narrow tooth length = 35 Deg
// Narrow tooth gap = 55
toothAngles[0] = 620; // Tooth before Narrow Tooth Falling edge
toothAngles[1] = 668; // Tooth before Narrow Tooth Falling edge
toothAngles[2] = 710; // (Narrow) Tooth Rising edge
toothAngles[3] = 25; // (Narrow) Tooth Falling edge
toothAngles[4] = 80; // N+1 Tooth Rising edge
toothAngles[5] = 128; // N+1 Tooth Falling edge
toothAngles[6] = 170; // N+2 Tooth Rising edge
toothAngles[7] = 218; // N+2 Tooth Falling edge
toothAngles[8] = 260; // N+3 Tooth Rising edge
toothAngles[9] = 308; // N+3 Tooth Falling edge
toothAngles[10] = 350; // N+4 Tooth Rising edge
toothAngles[11] = 398; // N+4 Tooth Falling edge
toothAngles[12] = 440; // N+5 Tooth Rising edge
toothAngles[13] = 488; // N+5 Tooth Falling edge
toothAngles[14] = 530; // N+6 Tooth Rising edge
toothAngles[15] = 578; // N+6 Tooth Falling edge
triggerActualTeeth = 16; //Both sides of all teeth over 720 degrees
This is all theory at the moment, but hopefully should be possible to implement.
James