RPM ringing "boioioing" on low RPM tip in
04-30-2013, 11:12 AM
#25
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Below is a model of the driveline oscillation.
Looking at the top traces, the step input is the torque input, and the ringing waveform, is the reaction.
The bottom traces, is a scheme for reducing the oscillation. The torque pauses halfway up, for exactly half the oscillation period (85 ms), before stepping up again to the final value. See the ringing is greatly reduced. This is a trick I learned when I did motion control programming in a former life.
How do we do this in an ECU? One place it can be done is when you come out of injector decel shutoff, where said ringing is usually worst. When you commence firing the injectors, you only fire half of them for the period necessary, before firing all of them. In order to preserve response when rev-matching, disable this feature when in neutral or the clutch is depressed.
I know the OEs do something like this. My 540i has something like this, and I remember reading an old paper by Mazda of a strategy like this for the Mazda6, to improve comfort.
Looking at the top traces, the step input is the torque input, and the ringing waveform, is the reaction.
The bottom traces, is a scheme for reducing the oscillation. The torque pauses halfway up, for exactly half the oscillation period (85 ms), before stepping up again to the final value. See the ringing is greatly reduced. This is a trick I learned when I did motion control programming in a former life.
How do we do this in an ECU? One place it can be done is when you come out of injector decel shutoff, where said ringing is usually worst. When you commence firing the injectors, you only fire half of them for the period necessary, before firing all of them. In order to preserve response when rev-matching, disable this feature when in neutral or the clutch is depressed.
I know the OEs do something like this. My 540i has something like this, and I remember reading an old paper by Mazda of a strategy like this for the Mazda6, to improve comfort.
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05-07-2013, 09:59 AM
#28
How do we do this in an ECU? One place it can be done is when you come out of injector decel shutoff, where said ringing is usually worst. When you commence firing the injectors, you only fire half of them for the period necessary, before firing all of them. In order to preserve response when rev-matching, disable this feature when in neutral or the clutch is depressed.
I know the OEs do something like this. My 540i has something like this, and I remember reading an old paper by Mazda of a strategy like this for the Mazda6, to improve comfort.
I know the OEs do something like this. My 540i has something like this, and I remember reading an old paper by Mazda of a strategy like this for the Mazda6, to improve comfort.
-Raj
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