Air flow detector. Related Books Free with a 30 day trial from Scribd. Related Audiobooks Free with a 30 day trial from Scribd. Elizabeth Howell. Editor-in-Chief: Dipl. FH Horst Bauer. Editorial staff: Dipl. Karl-Heinz Dietsche, Dipl. Presentation: Dipl. Translation: Peter Girling. Reproduction, copying, or translation of this publication, including excerpts therefrom, is only to ensue with our previous written consent and with source credit.
Illustrations, descriptions, schematic diagrams, and other data only serve for explanatory purposes and for presentation of the text.
They cannot be used as the basis for design, installation, or scope of delivery. We assume no liability for conformity of the contents with national or local legal regulations. We are exempt from liability. We reserve the right to make changes at any time. Printed in Germany. English translation of the German edition dated: September K-Jetronic Since its introduction, the K-Jetronic Combustion in the gasoline engine gasoline-injection system has pro- The spark-ignition or ved itself in millions of vehicles.
Otto-cycle engine 2 This development was a direct result Gasoline-engine management of the advantages which are inherent Technical requirements 4 in the injection of gasoline with Cylinder charge 5 regard to demands for economy of Mixture formation 7 operation, high output power, and Gasoline-injection systems last but not least improvements to Overview 10 the quality of the exhaust gases K-Jetronic emitted by the vehicle. Whereas the System overview 13 call for higher engine output was the Fuel supply 14 foremost consideration at the start of Fuel metering 18 the development work on gasoline Adapting to operating conditions 24 injection, today the target is to Supplementary functions 30 achieve higher fuel economy and Exhaust-gas treatment 32 lower toxic emissions.
Electrical circuitry 36 Between the years and , Workshop testing techniques 38 the highly reliable, mechanical multi- point injection system K-Jetronic was installed as Original Equipment in series-production vehicles. Today, it has been superseded by gasoline injection systems which thanks to electronics have been vastly im- proved and expanded in their func- tions. Since this point, the K-Jetronic has now become particularly impor- tant with regard to maintenance and repair.
Combustion in the gasoline engine Combustion in the gasoline engine combustion process pressurizes the The spark-ignition cylinder, propelling the piston back down, or Otto-cycle engine exerting force against the crankshaft and performing work. The powerplant is an internal-combustion IC primary design concept used to govern engine that relies on an externally- this gas transfer in powerplants for generated ignition spark to transform the automotive applications is the four-stroke chemical energy contained in fuel into principle, with two crankshaft revolutions kinetic energy.
These valves open and then drawn into the engine by the suction close the intake and exhaust tracts generated as the pistons descend. The leading to and from the cylinder: future will see increasing application of systems that inject the fuel directly into the 1st stroke: Induction, combustion chamber as an alternate 2nd stroke: Compression and ignition, concept.
As the piston rises, it compresses 3rd stroke: Combustion and work, the mixture in preparation for the timed 4th stroke: Exhaust. The heat released in the Intake valve: open, Fig. Just before thus initiating combustion and the the piston reaches top dead center TDC attendant temperature rise.
As an curves to the demands of automotive example, increasing the compression ratio operation under real-world conditions. The latitude Exhaust stroke for increasing compression ratio is Intake valve: closed, restricted by knock.
This term refers to Exhaust valve: open, uncontrolled mixture inflammation charac- Piston travel: upward, terized by radical pressure peaks.
Combustion: none. Combustion knock leads to engine damage. Suitable fuels and favorable As the piston travels upward it forces the combustion-chamber configurations can spent gases exhaust out through the be applied to shift the knock threshold into passage exposed by the open exhaust higher compression ranges.
The entire cycle then recommences with a new intake stroke. The intake and Power stroke exhaust valves are open simultaneously Intake valve: closed, during part of the cycle. The driver exercises during the power stroke and is defined by direct control over throttle-valve opening the following factors: on conventional injection systems via the — The mass of the air available for physical link with the accelerator pedal. Ignition emissions control system Figure 2.
In consequence, modifications to same time satisfying strict criteria in the enhance maximum engine power and areas of torque almost always entail increasing — Exhaust emissions, the maximum possible cylinder charge.
Residual gases The portion of the charge consisting of residual gases is composed of — The exhaust-gas mass that is not Cylinder charge discharged while the exhaust valve is open and thus remains in the cylinder, Elements and The gas mixture found in the cylinder — The mass of recirculated exhaust gas once the intake valve closes is referred to on systems with exhaust-gas recircu- as the cylinder charge, and consists of lation, Figure 2.
Although the residual gas does not Fresh gas participate directly in combustion, it does The fresh mixture drawn into the cylinder influence ignition patterns and the actual is a combination of fresh air and the fuel combustion sequence. The effects of this entrained with it. While most of the fresh residual-gas component may be thoroughly air enters through the throttle valve, desirable under part-throttle operation. Gasoline- are needed to meet higher torque on a supplementary EGR valve linking engine demand.
These higher angles reduce the the intake and exhaust manifolds. Precisely reg- exhaust gas when this valve is open. Throttle valve Dynamic pressure charging The power produced by the spark- A supercharging or boost effect can be ignition engine is directly proportional to obtained by exploiting dynamics within the mass airflow entering it.
Control of the intake manifold. Mechanical supercharging Figure 3 illustrates the conceptual Further increases in air mass are correlation between fresh-air charge available through the agency of density and engine speed as a function Fig. Throttle-valve map for spark-ignition engine Throttle valve at intermediate aperture Gas exchange The intake and exhaust valves open and close at specific points to control the transfer of fresh and residual gases.
The Throttle valve ramps on the camshaft lobes determine completely open both the points and the rates at which the valves open and close valve timing to define the gas-exchange process, and Fresh gas charge with it the amount of fresh gas available for combustion.
Valve overlap defines the phase in which the intake and exhaust valves are open simultaneously, and is the prime factor in determining the amount of residual gas remaining in the cylinder. The mass of residual gas completely closed can also be increased using "external" min. Clutches are often used to control compressor activation. Parameters Exhaust-gas turbochargers Air-fuel mixture Here the energy employed to power the Operation of the spark-ignition engine is compressor is extracted from the exhaust contingent upon availability of a mixture gas.
The naturally-aspirated engines cannot theoretical ideal for complete combustion exploit directly owing to the inherent is a mass ratio of In concrete terms pansion characteristics resulting from the this translates into a mass relationship of crankshaft concept. One disadvantage is This back- roughly 9, litres of air for complete pressure stems from the force needed to combustion of 1 litre of fuel.
The turbocharger is thus a absolutely minimal fuel consumption combination of the turbine in the exhaust- would be possible only with excess air, fas flow and the impeller that compresses but here limits are imposed by such the intake air. The air-fuel mixture is also vital in determining the efficiency of exhaust-gas Fig.
As this implies, the mixture-formation system must be capable of responding to UMME 1 1 3 1 4 2 4 1 a range of variable requirements.
Engine rpm nn 7 Gasoline- Excess-air factor deficiencies of As can be seen, there is no requirement for stoichiometric com- single excess-air factor which can bustion. Air to the theoretical requirement.
Beyond the Optimal combustion from current en- lean-burn limit the mixture ceases to be gines equipped with manifold injection ignitable and combustion miss sets in, relies on formation of a homogenous accompanied by substantial degener- mixture as well as precise metering of the ation of operating smoothness.
This makes In engines featuring systems to inject fuel effective atomization essential. These droplets laws. Adapting to specific Idle and part-load Mixture operating conditions Idle is defined as the operating status in formation which the torque generated by the engine Certain operating states cause fuel is just sufficient to compensate for friction requirements to deviate substantially from losses.
The engine does not provide the steady-state requirements of an engine power to the flywheel at idle. Part-load or warmed to its normal temperature, thus part-throttle operation refers to the necessitating corrective adaptations in the range of running conditions between idle mixture-formation apparatus.
The follow- and generation of maximum possible ing descriptions apply to the conditions torque. Sudden variations in Post-start phase manifold pressure of the kind encountered Following low-temperature starts, in response to rapid changes in throttle- supplementary fuel is required for a brief valve aperture cause fluctuations in the period, until the combustion chamber fuel layer on the walls of the intake tract.
This richer mixture manifold pressures. The fuel responds also increases torque to furnish a with lower vaporization rates and the fuel smoother transition to the desired idle layer within the manifold runners expands.
A portion of the injected fuel is thus lost in wall condensation, and the engine goes Warm-up phase lean for a brief period, until the fuel layer The warm-up phase follows on the heels restabilizes. In an analogous, but inverted, of the starting and immediate post-start response pattern, sudden deceleration phases.
At this point the engine still leads to rich mixtures. A temperature- requires an enriched mixture to offset the sensitive correction function transition fuel condensation on the intake-manifold compensation adapts the mixture to walls.
This promotes fuel precip- itation within the intake manifold, with Trailing throttle overrun the formation of condensate fuel that will Fuel metering is interrupted during trailing only vaporize later, once temperatures throttle. Although this expedient saves have increased. These factors make it fuel on downhill stretches, its primary necessary to provide progressive mixture purpose is to guard the catalytic converter enrichment in response to decreasing against overheating stemming from poor temperatures.
Gasoline- injection systems Gasoline-injection systems Carburetors and gasoline-injection sys- Representative examples are the various tems are designed for a single purpose: versions of the KE and L-Jetronic systems To supply the engine with the optimal air- Figure 1. Gasoline injection systems, Mechanical injection systems and electronic systems in particular, are The K-Jetronic system operates by better at maintaining air-fuel mixtures injecting continually, without an exter- within precisely defined limits, which nal drive being necessary.
Instead of translates into superior performance in being determined by the injection valve, the areas of fuel economy, comfort and fuel mass is regulated by the fuel convenience, and power. Increasingly distributor.
As conditions. In this UMKY type of system each cylinder has its own injector discharging fuel into the area 6 10 directly in front of the intake valve. The combination of air and fuel common to Overview actual injected fuel quantity is regulated conventional injection systems. This is one by controlling the injector's opening time of the new system's prime advantages: It with the pressure-loss gradient through banishes all potential for fuel condensation the valve being taken into account in within the runners of the intake manifold.
External mixture formation usually Examples: L-Jetronic, LH-Jetronic, and provides a homogenous, stoichiometric air- Motronic as an integrated engine-manage- fuel mixture throughout the entire ment system. In contrast, shifting the mixture-preparation process into the Single-point fuel injection combustion chamber provides for two Single-point throttle-body injection TBI distinctive operating modes: fuel injection is the concept behind this With stratified-charge operation, only the electronically-controlled injection system mixture directly adjacent to the spark plug in which a centrally located solenoid- needs to be ignitable.
The remainder of the operated injection valve mounted air-fuel charge in the combustion chamber upstream from the throttle valve sprays can consist solely of fresh and residual fuel intermittently into the manifold. Mono- gases, without unburned fuel. This strategy Jetronic and Mono-Motronic are the furnishes an extremely lean overall mixture Bosch systems in this category Figure 2. Systems for internal Homogenous operation reflects the mixture formation conditions encountered in external mixture Direct-injection DI systems rely on formation by employing uniform solenoid-operated injection valves to spray consistency for the entire air-fuel charge fuel directly into the combustion chamber; throughout the combustion chamber.
Perfect combustion process. This operational atomization of the fuel emerging from the mode is employed for WOT operation. The story of fuel injection The story of fuel injection injection system: the intake-pressure- The story of fuel injection extends controlled D-Jetronic!
In , the K-Jetronic was the first A short time later the uses of the ven- automotive system to incorporate a turi-effect for carburetor design were Lambda closed-loop control.
This system combined L-Jetro- injection pumps in The first nic with electronic program-map con- aircraft engine featuring Bosch fuel in- trol for the ignition. The first automo- jection, a 1,hp unit, entered series tive microprocessor! Sev- By the end of , around 64 million eral years later a unit was installed in Bosch engine-management systems the SL, the legendary production had been installed in countless types of sports car from Daimler-Benz.
In alone, the ment on mechanical injection pumps figure was 4. Bosch gasoline fuel injection from the year 12 K-Jetronic Fuel supply An electrically driven fuel pump delivers K-Jetronic the fuel to the fuel distributor via a fuel System overview accumulator and a filter.
The fuel distribu- tor allocates this fuel to the injection The K-Jetronic is a mechanically and valves of the individual cylinders. Specific operating conditions of the engine require corrective intervention in Fuel metering mixture formation and this is carried out The amount of air, corresponding to the by the K-Jetronic in order to optimize position of the throttle plate, drawn in by starting and driving performance, power the engine serves as the criterion for output and exhaust composition.
Owing metering of the fuel to the individual to the direct air-flow sensing, the K-Je- cylinders. The amount of air drawn in by tronic system also allows for engine the engine is measured by the air-flow variations and permits the use of facilities sensor which, in turn, controls the fuel for exhaust-gas aftertreatment for which distributor. The air-flow sensor and the precise metering of the intake air quantity fuel distributor are assemblies which is a prerequisite. The K-Jetronic was originally designed Injection occurs continuously, i.
Mixture enrichment is lambda closed-loop control. In addition, supple- — Fuel supply, mentary functions such as overrun fuel — Air-flow measurement and cutoff, engine-speed limiting and closed- — Fuel metering. Gasoline- Fuel supply available. This avoids the formation of injection fuel-vapor bubbles and achieves good systems The fuel supply system comprises hot starting behavior.
An electrically driven roller-cell pump The rotor plate which is eccentrically pumps the fuel from the fuel tank at a mounted in the pump housing is fitted pressure of over 5 bar to a fuel accu- with metal rollers in notches around its mulator and through a filter to the fuel circumference which are pressed against distributor. From the fuel distributor the the pump housing by centrifugal force fuel flows to the injection valves.
Category: Automotive download. Tags: robert bosch cylinders chamber pressure basic injection quantity comparison electric fuel piston travels specific fuel. Editor-in-Chief: Dipl. FH Horst Bauer. Editorial staff: Dipl.
Karl-Heinz Dietsche, Dipl. BA Jrgen Crepin. Presentation: Dipl. Translation: Peter Girling. Reproduction, copying, or translation of this publication, including excerpts therefrom, is only to ensue with our previous written consent and with source credit.
Illustrations, descriptions, schematic diagrams, and other data only serve for explanatory purposes and for presentation of the text. They cannot be used as the basis for design, installation, or scope of delivery. We assume no liability for conformity of the contents with national or local legal regulations. We are exempt from liability. We reserve the right to make changes at any time. Printed in Germany. Imprim en Allemagne. English translation of the German edition dated: September K-Jetronic Since its introduction, the K-Jetronic Combustion in the gasoline engine gasoline-injection system has pro- The spark-ignition or ved itself in millions of vehicles.
Otto-cycle engine 2 This development was a direct result Gasoline-engine management of the advantages which are inherent Technical requirements 4 in the injection of gasoline with Cylinder charge 5 regard to demands for economy of Mixture formation 7 operation, high output power, and Gasoline-injection systems last but not least improvements to Overview 10 the quality of the exhaust gases K-Jetronic emitted by the vehicle.
Whereas the System overview 13 call for higher engine output was the Fuel supply 14 foremost consideration at the start of Fuel metering 18 the development work on gasoline Adapting to operating conditions 24 injection, today the target is to Supplementary functions 30 achieve higher fuel economy and Exhaust-gas treatment 32 lower toxic emissions. Electrical circuitry 36 Between the years and , Workshop testing techniques 38 the highly reliable, mechanical multi- point injection system K-Jetronic was installed as Original Equipment in series-production vehicles.
Today, it has been superseded by gasoline injection systems which thanks to electronics have been vastly im- proved and expanded in their func- tions.
Since this point, the K-Jetronic has now become particularly impor- tant with regard to maintenance and repair. This manual will describe the K-Jetronics function and its particu- lar features.
Combustion in the gasoline engine Combustion in the gasoline engine combustion process pressurizes the The spark-ignition cylinder, propelling the piston back down, or Otto-cycle engine exerting force against the crankshaft and performing work.
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