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SYSTEM SOLUTIONS FOR MODERN DIESEL ENGINE CONCEPTS * Written by Robert Bosch GmbH in conjunction with Jack Holstein, National Service Manager, Australia - Special thanks go out to the people of the Association of Australian Diesel Specialists Inc. for sending me a copy of their Magazine (Diesel Torque) that had this article included in it...Great job with the magazine...keep up the good work. Quality and expertise in automotive equipment Since Robert Bosch introduced the low-voltage magneto for motor vehicles as it's first product in 1897, the company has been growing steadily and developed into the Bosch Group operating on an international scale. In the area of automotive equipment, the Bosch name is synonymous with quality, performance and precision. Some examples are ABS, suspension and safety systems, lighting equipment, engine management systems, electrical and electronic automotive body equipment, semiconductors and electronic control units as well as starters and alternators. Through innovative development work, precision in production and high quality standards, Bosch will continue to help make motor vehicles even safer, cleaner and more fuel efficient. Within the Bosch Automotive Equipment Sector, the K5 product division is responsible for diesel injection systems.
In 1887, after a development
time of five years, Rudolf Diesel presented his third and first
This was the beginning of a partnership-like cooperation between manufacturers of diesel engines and Bosch which repeatedly resulted in major developments. For example, after the introduction of distributor pumps on 1964, diesel engines became increasingly common in cars. Since 1983 Bosch electronics have been used to optimize diesel injection controls. Because of developments such as these, today's diesel engines are regarded as a reliable, economical and durable power plant in all types of vehicles. For a long time, diesel engines were associated with low with low power, a sacrifice in convenience and a difficult to control exhaust behavior. Typical characteristics such as surging and idle vibration were eliminated by refining the mechanical portion of the injection equipment and by utilizing electronic control systems. These measures improved the driveability and stability of the idle speed and contributed significantly to a reduction to fuel consumption and emissions. The electronically controlled Bosch injection systems assume numerous additional functions such as the control of the injected fuel quantity as a function of ambient temperature and the air quantity drawn in, the control of exhaust gas recirculation as well as cruise control.
During the first decades, diesel technology was concerned with improving performance and reducing fuel consumption. Today the focus is on stricter requirements regarding environmental compatibility. Engines - and thus also the injection equipment must meet increasingly stricter standards regarding emission levels as well as particulate and noise emissions.
The more flexibility parameters such as the start of injection, injection rate, direction of injection, injection pressure and the air-fuel ratio can be adapted to given engine requirements, the lower the pollutant emissions of diesel engines. Electronically controlled injection systems allow the flexible matching of these values by means of electronically stored maps. The control of the start of injection and the air quantity keeps emissions stable throughout the entire engine life. This is supplemented by electronically controlled exhaust-gas recirculation.
Clean exhaust from diesel engines is not only achieved through the electronic control of injection but also through the continued development of all mechanical components. Bosch developed various concepts together with engine design engineers. All concepts are suitable for high pressure and work with an electronic control: * Control sleeve in-line pump
Diesel engines have always
been regarded as fuel efficient. They have the best thermal efficiency
Having been widely used in heavy commercial vehicles for a long time, DI engines are now being installed more often in smaller delivery trucks and cars. In the past combustion noise of DI engines was inherently louder than that of pre- or swirl chamber engines. Today, DI engines have become so quiet through continued development of the injection systems that even luxury cars benefit from their typical advantages.
Bosch offers it's partners in the engine industry a wide range of injection components. Whether dealing with passenger cars, small pick-up trucks, commercial vehicles, machines, ships, agricultural machinery - there is an injection system precisely tailored to the particular requirements of each application. Modern injection systems can contain a host of functions among them the electronic control of the start of injection.
On diesel engines the injection system makes sure fuel is injected into the combustion chamber at the right moment with the required pressure and the correct amount. Systems such as the proven in-line pump or newly developed control sleeve pump meet these requirements with a high degree of reliability. The injection system precisely meters the fuel during the injection process at a high pressure and with the accuracy of a fraction of a thousandth of a second. Fuel is injected up to 250 times per second at speeds over 2,000 km/h. Today, the combination of precision and high flexibility is being achieved more often through electronic injection controls.
Diesel injection systems have achieved a high degree of technical maturity. Mechanical control systems have proven their reliability and precision for many years. The first electronic diesel control (EDC) has been a standard feature of distributor pumps since 1983. With the use of electronics it was possible to adjust the start of injection and exhaust-gas recirculation more accurately and flexibly to the engine requirements. Electronic systems improve fuel economy and reduce the amount of pollutants in the exhaust. In addition, a significant improvement of the performance characteristics was achieved with the introduction of electronic fuel quantity control in 1986. Among other things the EDC carries out the following functions: * Start quantity control The electronic diesel control is able to collect different data from the engine and operating conditions with sensors. It flexibly processes the data with characteristic curves or maps with two- or multi- dimensional representation in the control unit.
Since all data are available in uniform, digitalised form, the diesel injection system can be easily interconnected with other vehicle systems. For example: * Data exchange with the anti
lock braking system (ABS) and traction control (ASR)
In-line pumps have been used for years in car, commercial vehicle, tractor, industrial and stationary engines. Together with governors, timing devices and various add-on modules from the Bosch module system, these injection pumps offer a wide range of possible applications.
For in-line pumps Bosch offers system solutions in the form of electronic add-on modules or fully electronic controls. Idle control and driveability can be optimized with add-on modules. There are also solutions for future emission standards. The electronic start of injection control influences the mixture formation and combustion. Emissions of nitrogen oxides and unburned hydrocarbons are significantly reduced.
To meet stricter emission standards, commercial vehicle diesel engines require a high injection pressure and a precise start of injection. With the newly developed control sleeve pump, the start of injection and the delivered fuel quantity can be freely selected by means of maps on commercial vehicle diesel engines. Linear solenoids electronically control the injected fuel quantity and the start of injection. Within a predetermined range, the sleeve riding on the plunger can be adjusted to vary the start of injection. The control sleeve pump can be mounted on engines without any difficulty. The classical in-line pump can be easily replaced by the new control sleeve pump which in addition to injection pressures of up to 1400 bar at the nozzle offers precise start of injection control. This new system also opens up the possibility of integrating diesel injection into a network of electronic controls. The combination of electronically controlled control sleeve pump with traction control (ASR) - an important feature for heavy commercial vehicles - is especially useful and advisable.
The new electronically controlled VP 44 high pressure radial piston distributor pump generates pump pressures of more than 1000 bar and nozzle pressures of over 1500 bar. The high atomization energy thus produced at the nozzles, plus the variable delivery rate and pre-injection lead to a very clean burning engine with a smooth and consequently quiet combustion process. The fast-response adjustment of injection timing and high precision metering of the fuel by fast acting solenoid valves form the basis for the high power output and low fuel consumption of modern diesel engines.
Operating Principle
Features: * Radial-piston configuration
for pump pressures up to 100 bar.
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working diesel engine. However,
because of it's weight and size this engine could only be used
for stationary purposes for three decades. In particular, what
was lacking was a compact, light and at the same time efficient
injection pump. In 1922 Robert Bosch decided to develop diesel
injection systems. In 1927 the first mass-produced injection pumps
left the plant. This created the prerequisites for the high speed
diesel engine used in motor vehicles. The first diesel car went
into production in 1936. 
In addition to the continuous
improvement of existing products and systems, Bosch is constantly
working on new developments. Solenoid valve technology for distributor
pumps and single cylinder pumps (unit injector, unit pump), common
rail as well as the cross section controlled nozzles are current
examples. 
and thus the lowest fuel consumption
of all internal combustion engines. If we take advantage of the
principle of direct injection, fuel consumption can be reduced
by another 15% compared to conventional pre- and swirl chamber
engines. 
