Jetronic is a trade name for a type of automobile fuel injection technology for petrol engines, developed and marketed by the German technology company Robert Bosch GmbH (commonly referred to as Bosch), from the 1960s onwards. Bosch licensed the concept to many automobile manufacturers. There are several variations of the technology, which represent technological developments and refinements as time passed.
D-Jetronic (1967–1976)
Analog fuel injection. The 'D' is an abbreviation from German: "Druck", which means pressure. The depression (vacuum) is measured using a pressure sensor located in the intake manifold, in order to calculate the duration of the fuel injection pulses. Originally, this system was just called Jetronic, but the name D-Jetronic was later used to distinguish it from the newer versions.
K-Jetronic (1974–1988)
Mechanical fuel injection. The 'K' stands for German: "Kontinuierlich", meaning continuous. This is different from pulsed injection systems, in that the fuel flows continuously from all injectors, whilst the fuel pump pressurises the fuel up to approximately 5 bar (72.5 psi). The air that is taken in is also weighed - to determine the amount of fuel to inject. Commonly called 'Continuous Injection System' (CIS) in the USA. This system has no lambda loop or lambda control. K-Jetronic was installed into a number of Mercedes-Benz, Volkswagen Group, Ferrari, BMW, Volvo, Saab and Ford automobiles.
K-Jetronic (Lambda)
A variant of K-Jetronic with closed-loop lambda control, also named Ku-jetronic, the letter u denominates The USA. The system was developed to comply with Californian exhaust emission regulations, and later replaced by KE-Jetronic. First introduced in the Volvo 265 in 1976.
KE-Jetronic (1985–1993)
Electronically controlled mechanical fuel injection. The engine control unit (ECU) may be either analog or digital, and the system may or may not have closed-loop lambda control. Commonly known as 'CIS-E' in the USA. The later KE3 (CIS-E III) variant features knock sensing capabilities.
L-Jetronic (1974–1989)
Analog fuel injection. The 'L' in its name is derived from German: "Luft", meaning air. This system uses a vane-type air flow meter (AFM), which is taken from the German: LuftMassenMesser (LMM) in all Bosch documentation. Due to the use of custom-designed integrated circuits, its engine control unit (ECU) was much simpler and more reliable than that used by D-Jetronic. It was used heavily in 1980s-era European cars.[1] Licensing some of Bosch's L-Jetronic concepts and technologies, Lucas, Hitachi Automotive Products, NipponDenso, and others produced similar fuel injection systems for Asian car manufacturers. Despite any physical similarity between L-Jetronic components and those produced under license by other manufacturers, the non-Bosch systems should not be called L-Jetronic, and the parts are usually incompatible.
LE1-Jetronic, LE2-Jetronic, LE3-Jetronic (1981–1991)
This is a simplified and more modern variant of L-Jetronic. The ECU was much cheaper to produce due to more modern components, and was more standardised than the L-Jetronic ECUs. The connections between AFM and ECU are simplified. Three variants of LE-Jetronic exist: LE1, the initial version. LE2 (1984–), featured cold start functionality integrated in the ECU, which does not require the cold start injector and thermo time switch used by older systems. LE3 (1989–), featuring miniaturised ECU with hybrid technology, integrated into the junction box of the AFM.
LU-Jetronic (1983–1991)
The same as LE2-Jetronic, but with closed-loop lambda control. Initially designed for the US market.
LH-Jetronic (1982–1998)
Digital fuel injection, introduced for California bound 1982 Volvo 240 models. The 'LH' stands for German: "Luftmasse-Hitzdraht" - the hotwire anemometer technology used to determine the mass of air into the engine. This air mass meter is called HLM2 (Hitzdraht-LuftMassenmesser 2) by Bosch. The LH-Jetronic was mostly used by Scandinavian car manufacturers, and by sports and luxury cars produced in small quantities, such as Porsche 928. The most common variants are LH 2.2, which uses an Intel 8049 (MCS-48) microcontroller, and usually a 4 kB programme memory, and LH 2.4, which uses a Siemens 80535 microcontroller (a variant of Intel's 8051/MCS-51 architecture) and 16 or 32 kB programme memory. LH-Jetronic 2.4 has adaptive lambda control, and support for a variety of advanced features; including electronic boost control and fuel enrichment based on exhaust gas temperature (ex. Volvo B204GT/B204FT engines). Some later (post-1995) versions contain hardware support for advanced diagnostics according to ISO 9141 (a.k.a. OBD-II) and immobiliser functions. The 1995 and newer Volvo 940 vehicles are one such example.
Mono-Jetronic (1988–1995)
Digital fuel injection. This system features one centrally positioned fuel injection nozzle. In the US, this kind of single-point injection was marketed as 'throttle body injection' (TBI, by GM), or 'central fuel injection' (CFI, by Ford). Mono-Jetronic is different from all other known single-point systems, in that it only relies on a throttle position sensor for judging the engine load. There are no sensors for air flow, or intake manifold vacuum. Mono-Jetronic always had adaptive closed-loop lambda control, and due to the simple engine load sensing, it is heavily dependent on the lambda sensor for correct functioning. The ECU uses an Intel 8051 microcontroller, and usually 16 kB of programme memory. Usually no advanced diagnostics.
See also
References
- ^ "L-Jetronic" (archived usenet message). 22 June 1993. http://yarchive.net/car/l-jetronic.html. Retrieved 17 November 2009.
External links
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