Monomotronic
The Mono-Motronic is a fully electronic engine management system for gasoline engines with central injection (SPI), which was manufactured by Robert Bosch GmbH from 1989.
The Mono-Motronic is a further development of the Mono-Jetronic ; Motronic, a freely programmable motor control from Robert Bosch GmbH, is used as the control hardware . The basic functions and control procedures were taken over by the Mono-Jetronic.
Injection process
The Mono-Motronic uses a SPI (Single Point Injection) Central point injection without air mass meter for 4 cylinders - gasoline engines with three-way catalyst (for some countries there is a version for vehicles without catalyst, for leaded fuels). So it is an indirect, central, intermittent, electronically controlled injection with one injection valve for all cylinders and external mixture formation . The fuel pressure is 1 bar. The fuel is injected into the intake manifold upstream of the throttle valve . The Mono-Motronic was the first fully electronic engine control system with lambda control for the lower compact car class .
Innovations compared to its predecessor, the Mono-Jetronic
- integrated electronic ignition control
- Ignition distributor without adjustment device
- idling stabilization on the ignition side
- extended on-board diagnosis with fast data transfer
- it recognizes changed environmental and operating conditions ( adaptive system )
- Emergency running properties
The decisive improvement over the Mono-Jetronic lies in the ignition map , which enables better and cleaner combustion .
Main control loop, α / n control
The injection time and thus the amount of fuel as well as the ignition point are calculated from the measured variables speed [n] and throttle valve angle [α], taking into account correction variables such as air temperature and exhaust gas composition (lambda control). The throttle valve is operated mechanically using the accelerator pedal . The throttle valve angle is measured using two throttle valve potentiometers, the speed is derived from the signal from the Hall sensor of the ignition distributor. This type of control is called α / n control .
Sensors / actuators
Main sensors
- Throttle potentiometer
- Open circuit
- Hall sender of the ignition distributor
- Lambda probe
- Air temperature sensor ( NTC resistor)
- Coolant temperature sensor (NTC resistor)
Main actors
- Throttle valve actuator
- Injector
- Output stage of the ignition coil / the ignition transformer
Other sensors / actuators
In addition to the main sensors, other signals such as the readiness for air conditioning or the air conditioning compressor are processed, for example to increase the speed shortly before the air conditioning compressor is switched on and thus to avoid a drop in speed. Other actuators such as the fuel pump are also activated.
Further development in 1994
In 1994 an improved version of the Mono-Motronic came onto the market. It had greater driving comfort , lower pollutant emissions and lower fuel consumption . There were minor structural changes, such as a new 45-pin connector (previously 35-pin).
- Idle stabilization by means of throttle valve actuator tappets
- Sender for throttle valve positioner
- Control unit processes speed signal
- Knock sensor
General
The Mono-Motronic failed because of the increasing demands on exhaust quality. The main disadvantage was the central injection valve. In particular, it was the poor uniform distribution of the fuel that caused two of the cylinders to run with λ> 1, i.e. lean, while two of them ran rich (λ <1). However, the incorrect setting was not a constant offset that could have been remedied by reworking the intake manifold, but changed depending on the speed and / or engine load. Even if the average air ratio was 1, that of the individual cylinders was unequal to one another, so that the generation of pollutants was unfavorable.
Even with rapidly changing operating points, as is the case with highly dynamic operation, the central injection was unfavorable. Part of the fuel forms a fuel film in the intake manifold which, in contrast to the highly dynamic air column in the intake manifold, is sluggish and is transported more slowly. The result is a brief emaciation, which is countered with an acceleration enrichment. In the event of a delay, the fuel film is the cause of a brief accumulation of the mixture. The deliberate enrichment and the sluggish film can lead to oil dilution , especially in short-distance traffic . When the engine warms up, some of the gasoline dissolved in the oil evaporates, which causes a higher proportion of unburned hydrocarbons ( HC value ) in the exhaust gas , which, however , is broken down when the exhaust gas aftertreatment works .
The Mono-Motronic has long been installed in vehicles in the lower performance class because of the low system costs. The main customers were Volkswagen, Audi, Fiat, Seat, Škoda and Volvo. One of the last vehicles with this injection system until 2000 was the Golf III / IV Cabriolet with the 1.8 liter engine (55/66 kW).
With the Multec central injection, General Motors had its own system with a similar selection of components, which was mainly installed in Opel vehicles. The Multec central injection had an intake manifold pressure sensor and was therefore superior to the simpler α / n control of the Mono-Motronic.
Web links
Mono-Motronic overall system ( Memento from September 24, 2018 in the Internet Archive )
Example: Mono-Motronic circuit diagram ( Memento from September 3, 2018 in the Internet Archive )
literature
- Karl-Heinz Dietsche, Thomas Jäger, Robert Bosch GmbH: Automotive pocket book. 25th edition, Friedr. Vieweg & Sohn Verlag, Wiesbaden 2003, ISBN 3-528-23876-3 .
Individual evidence
- ↑ Engine management gasoline injection 2008/2009
- ↑ The electronic gasoline injection from Bosch has been reducing gasoline consumption and CO2 emissions for 40 years ( Memento from August 12, 2007 in the Internet Archive )
- ↑ Examples of the use of mono-motronic at Volkswagen ( Memento of the original from December 25, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
