Electrical Description of EGM
Status September 2003 (EvoBus-Service / AFT)
Page: 50 of 83
Hardware description:
The contact current when a button is pressed is approx. 10 mA. In addition, the inputs to the buttons are
short-circuit-proof to earth and insensitive to dirt resistances parallel to the buttons. The dirt resistances
can have values down to 10 K
Ω
.
3.4
Actuator technology
3.4.1
Gas injectors
Guide values for Bosch valves CNG 1.3A and for the supply lines
Resistance:
4.6
Ω
at
±
0.5
Ω
at 20 °C
Valve current (peak/hold):
2 A/0.5 A
Average opening time (8 bar):
approx. 2 ms
Wiring harness resistance:
< 200 m
Ω
3.4.2
Gas injector actuation
The gas injector actuation is primarily intended to ensure that the gas injectors open reliably and the fed
gas mass is transferred. In contrast to PLD, compliance with an exact start of gas injection only plays a
subordinate role. The calculated angle for start of gas delivery is therefore the start of the electrical
actuation. This takes place sequentially, both for multipoint and for single-point engines. Hardware and
software are designed so that overlapping of actuation is possible. The actuation sequence over time
takes place purely controlled, i.e. there is no feedback on the opening state of the valve. For diagnosis
purposes and for fast hardware-side output state switch-off, each valve bank is provided with its own
current measurement and interrupt triggering.