2005-2006
The
major change in design of the piggyback from last year is the input of
the Throttle Position Sensor into the stamp. This gives us an
additional way to control the A/F ratio inside of the engine.
Particularly when the sled is at idle, this is where emissions
could be improved the most from the previous year. The design of the
micro controller can be seen below in Figure 1.
Figure 1: Micro controller design
The stamp used last year will need to be slightly altered to be able to
take the Throttle Position Sensor as an input. The Analog to Digital
converter used in the circuit can control two inputs. Last year the
converter took the O2 sensor input and used a ground wire, which we
have determined, was not used in the circuit. So we have both the
Throttle Position Sensor and the O2 sensor input into the same Analog
to Digital converter. The bench tested version of this can be
seen below in Figure 2.
Figure 2: Bench version of stamp with dummy inputs
The
bench tested stamp only contains the A/D converter and the Digital
Potentiometer on it. The basic stamp is built into the green circuit
board that is used. A further schematic of the piggyback micro
controller can be seen below in Figure 3.
Figure 3: Micro Controller Schematic
