Synerject Port Injection System

Port Injection (PI) System	Home Products Engine Management Systems Port Injection

Emissions regulations for all vehicles in all countries are being implemented, or made more stringent if already existing, to reduce smog and pollution, especially in large cities. This process started in the automotive area but has now extended to motorcycle, marine and recreational vehicles. This is leading to the adoption of Engine Management Systems (EMS) and fuel injection technologies to better control the combustion and after-treatment processes to reduce pollutants. As shown in graph 1, as the regulations become more stringent different technologies will be required for both two and four-stroke engines.

Graph 1

Synerject provides its customers with Port Injection (PI) EMS on a range of engine types and applications. Figure 1 shows a single-cylinder Motorcycle EMS system in a reasonably complex form; however simple system implementations are also available. The Engine Control Unit (ECU) monitors engine sensors and driver demand from the Throttle Position Sensor (TPS) and using complex strategies controls the injection and ignition timing to provide good starting and drivability while retaining low emissions and fuel consumption. The TPS signal is used to determine the demand the rider is requesting and in conjunction with the inlet air pressure and temperature from the TMAP (Temperature Manifold Absolute Pressure) sensor and/or engine speed from the CPS (Crank Position Sensor) sensor calculate the engine combustion airflow. This calculation can be done by the simple alpha-n method or the more accurate speed-density method with air temperature and pressure compensation. Altitude compensation is done by measuring the pressure in the manifold from the TMAP when the manifold pressure is at ambient barometric pressure.

Figure 1
To control engine speed at idle and to improve cold-starting the engine cylinder head temp (air-cooled engine) or coolant temperature is measured and supplementary air bypass flow to the engine is controlled by the ABV (Air Bypass Valve). Once demand and airflow are measured and calculated then injection duration is calculated to obtain the correct air/fuel ratio for proper combustion. With the addition of an optional O2 sensor, the system is enhanced by feedback which determines the actual combustion air/fuel ratio achieved. In such a “Closed Loop System” air/fuel ratio scatter due to variance in engine and EMS components at production and infield can be compensated for. However, it should be remembered “Open Loop Systems” (without an optional O2 sensor) can still meet at least stage 1 emissions at a lower cost than a Closed Loop System. Injection and Ignition timings are calculated by the ECU and timed to occur by engine angle information read from the CPS. Engine operating cycle determination is done by the addition of a Cam Position Sensor (CAM) or in the case of a simple single-cylinder application, by calculation at engine start by monitoring the crankshaft rotational speed difference between the firing and non-firing engine strokes. Simple instrument clusters and immobilisers can be operated by pulse signals; more complex units can communicate to the ECU via the automotive bus technology CAN. EMS diagnostics can be carried out using simple tools via either CAM or RS232 signal interfaces to the ECU. Optional vehicle inputs and outputs can be added to improved vehicle functionality. Synerject’s Motorcycle PI EMS systems, with their range of ECU families and functionalities, can provide solutions for the low-cost entry-level single-cylinder through to the multi-cylinder high-end performance vehicle.