santorta
Automotive
- May 3, 2003
- 24
Hi,
I have a single cylinder air-cooled 4 stroke motorcycle engine. I need to model the ECT/CHT (Engine coolant temp sensor or Cylinder head sensor, acronym really doesn't matter since the temperature sensor is mounted in the cylinder block, machining a small area in fins).
I had a thought about this, and it is not easy to just infer or model CHT based on time since start of engine, RPM & load.
Since CHT depends on two things,
1. Heat transferred from Combusted gas to cylinder walls,
2. Heat taken away by air flowing over the cylinder(since the engine is air cooled).
Estimation of the heat generated in the combustion requires inputs like A/F ratio, spark timing, combustion efficiency, and thermal properties of the cylinder block(aluminium) to estimate the heat generated and transfered to the wall. This heat in the block, is carried away by the air flowing over it. Air flow velocity changes depends on vehicle speed, and we need to infer the vehicle speed by some means of RPM, load (since we don't have neither VSS input nor gear input (to infer VSPD)). Again the CHT values can't be validated during run time or at start of the engine (considering hot start)
if my analysis has loop holes or if u have better ideas do shoot-in.
Thanks,
Santo RTA
I have a single cylinder air-cooled 4 stroke motorcycle engine. I need to model the ECT/CHT (Engine coolant temp sensor or Cylinder head sensor, acronym really doesn't matter since the temperature sensor is mounted in the cylinder block, machining a small area in fins).
I had a thought about this, and it is not easy to just infer or model CHT based on time since start of engine, RPM & load.
Since CHT depends on two things,
1. Heat transferred from Combusted gas to cylinder walls,
2. Heat taken away by air flowing over the cylinder(since the engine is air cooled).
Estimation of the heat generated in the combustion requires inputs like A/F ratio, spark timing, combustion efficiency, and thermal properties of the cylinder block(aluminium) to estimate the heat generated and transfered to the wall. This heat in the block, is carried away by the air flowing over it. Air flow velocity changes depends on vehicle speed, and we need to infer the vehicle speed by some means of RPM, load (since we don't have neither VSS input nor gear input (to infer VSPD)). Again the CHT values can't be validated during run time or at start of the engine (considering hot start)
if my analysis has loop holes or if u have better ideas do shoot-in.
Thanks,
Santo RTA