Multec
The Multec is an electronically controlled injection system (single point injection) that injects centrally and intermittently into the intake manifold with electronic control of the ignition for gasoline engines . It belongs to the systems of external mixture formation .
"Multec" is the abbreviation for the English term "Multiple Technology" .
It is an injection system for car engines mainly used by General Motors from the mid-1980s ; the first vehicle on the German market with this injection system was the Opel Corsa-A with a 1.3i engine in September 1985.
Since the system works with an intake manifold pressure sensor , i.e. according to the p / n system (pressure / speed system), it is superior to the Monomotronic from Bosch , as it only evaluates the throttle valve angle and speed (α / n system).
Components and functionality
The main control variables are the intake manifold pressure and the engine speed (p / n system). The mixture formation system of the central injection is controlled electronically. The control unit receives information about intake manifold pressure, engine speed, throttle valve position , coolant temperature , intake air temperature and the mixture composition via the lambda probe . This information is processed into control signals for mixture formation, idling control , overrun fuel cut-off and for the ignition point. The fuel is metered with just one injection valve (Multec and Multec-SZ) at a central point. The injection valve is installed in the throttle valve injection housing directly above the throttle valve. The fuel-air mixture is distributed to the engine's cylinders via the manifold. The system pressure regulator limits the pressure upstream of the injection valve z. B. to 0.75 bar with low pressure injection. The injection valve is operated electromagnetically . The opening time is calculated by the control unit. Since the opening cross-section of the injection valve and the fuel pressure are constant, the amount of fuel injected is only determined by the opening time of the injection valve.
The bypass, English for bypass or lock-up , is a channel for bypassing the throttle valve . If the accelerator pedal is not pressed, the throttle valve is completely closed, which means that the engine no longer receives a mixture and dies. To prevent this, the bypass is opened by an electronic stepper motor (idle filling motor) or a cone valve of a motor installed in the duct, and the mixture bypasses the closed throttle valve and provides the motor with enough mixture for idling .
The idle filling motor is a stepper motor with an electromagnetic coil that moves a cone valve and thus opens or regulates the air supply through the bypass. It is a separate component that is connected to the control unit of the Multec system. It should take over the control of the idling speed in the warm-up phase and keep the idling speed of the warm engine constant under every load, for example when switching on the air conditioning . In addition, when the overrun fuel cut-off is activated, it briefly supplies air via the bypass to reduce exhaust emissions and act as a linkage damper on the throttle valve. By activating the stepper motor, the control unit adjusts the cone valve in the bypass channel that bypasses the throttle valve at up to 160 steps per second. As the load on the motor increases, the valve cone opens the bypass. A fully retracted valve cone results in the largest opening of the bypass and thus increased mixture volume - the idle speed increases.
Multec-M
The Multec-M has four injection valves, which are installed in the intake manifold just before the inlet valves, the pressure in front of the injection valves is 3 bar here. This variant is therefore a multipoint injection, which is comparable to the Bosch D-Motronic (p / n control) used mainly by French manufacturers today. Innovations at the Multec-M include: a. DIS module, knock control, camshaft sensor, intake air temperature sensor, secondary air injection.
swell
- Europa-Lehrmittel, Fachkunde Automotive Engineering , Edition 2001, page 302, ISBN 3-8085-2067-1
Individual evidence
- ↑ A mechanical, absorbing element to protect the component from vibrations and thus damage and malfunctions, which in this case increases the reliability and service life of the throttle valve.