Continental is exploiting further potential for
efficiency by using on-demand fuel pumps. Unlike the standard pumps currently used, they only feed the engine with just the amount of fuel it really needs. This intelligent principle saves between 60 and 70 per cent of electrical energy compared with traditional constant fuel supply systems. "The savings potential of two-thirds of the pump's electrical energy shows what a difference a modern on demand fuel feed system can make," says Dr Markus Distelhoff, Head of Continentals's Fuel Supply Business unit. "At the same time, the control electronics open up further potential benefits for OEMs and drivers." For example control electronics not only make it possible to convert to low-wear brushless motors, they also offer other ways of increasing efficiency. Integrating the electronics into the flange results in a module with commercial and technical benefits; contact-free sensors for measuring fuel levels in the tank, self-diagnosis by the pump and economical solution for detecting leaks can also be integrated into the electronics.
Helping to reduce CO2
Using a pump control system can, as a rule of thumb, reduce CO2 emission from a classical 1.8 litre engine by 1.5 to 2 g of CO2 per kilometer. But that's not all. Once the Control electronics are installed, a little extra expenditure will open up further benefits and can even lower the costs at system level. In addition to economic efficiency and comfort, the electronics can improve the reliability of the fuel feed system still further.
Continental has effected on-demand fuel pump control in different ways depending on the customer's requirements. For example, a sensor can measure the fuel pressure before the pump feeds it into the engine. The control electronics constantly adjust the pump's feed rate so that the ideal pressure is permanently maintained by means of a closed-loop system. But this also works without a sensor. Using the master-slave principle for example the engine management system can specify the ideal volume for the pump electronics to feed in.
The optimum solutions is to integrate the electronics into the flange itself because first, this shorten still further the length of cable required and second, it reduces the OEM's assembly effort since it only requires a ingle device to be installed on the production line. In addition to saving on assembly and logistics, less has to be spent on copper, plug connectors and housings.
Modularity facilitates their introduction
Essential, all pump motors can benefit from on-demand control because Continental has opted for graduate modularity. Pulse-width modulation makes on-demand control a possibility even for conventional DC motors. However, brushless motors (EC Motors) whose electrical rotational field is generated in the control electronics are more efficient. These motors alone can further reduce CO2 emissions by approximately 0.3g/km from petrol engines and 0.5g/km from diesel engines, respectively.
EC motors do not only exhibit dramatically reduced mechanical wear, they are also more impervious to variations in fuel grades. Contaminated fuel, colloquially referred to as 'bad fuel' can cause carbon brushes to burn out rapidly. Consequently, brushless motors are ideal for aggressive fuel up to and including E 100, i.e. pure alcohol. As a result of consistent modularity, Continental's family of EC motors can be exchanged one for one for traditional motors. Here, too, the production part approval process and series production have begun.
Speed is the trump Card
For cost reasons, when installed in vehicles, EC motors do not include speed sensors. Because of this, when the engine is started up, there is a brief pause until the engine speed can be calculated from the engine's electrical counter-pulses. However, since the precise fuel feed pressure needs to be attained as quickly as possible, Continental also incorporates an ASIC module in the control electronics. This reduces the time before speed synchronisation is reached to just 100ms. Other designs without ASICs need longer synchronisation times- up to 500ms, considerably in excess of what the OEMs specify. Combined with pressure relied valves, the inclusion of an ASIC produces as a fuel feed system which helps to meet even the most stringent emission requirements despite frequent engine starts.
Modularised fuel feed units
Modularised plays a similarity major role in integrate fuel feed units. Since today's fuel tanks come in the widest possible variety of shapes, some of them complex, every feed units needs to be an advantage. Continental's detailed knowledge allows the company to assume total responsibility for fuel feed, including all the feed unit sub-system interfaces to the tank.
'Continental has brought its entire electronics, engine sensor, valve and filter know-how, under a single roof. This means than we can cater for the complete range, from a 'best cost' system for the Tata Nano to a twin pump system for 'high power engines," said Distelhoff. "With over 90 million pumps sold already, we are not only the market leader in Europe but one of the world's two leading specialists in this area."
Exploiting the potential of electronics
Systematic exploitation of the pump's control electronics is paving the way for additional benefits. One example is the option of moving to wear-free sensors for measuring the fuel level in tank. Current system are generally based on level sensors for sliding contacts. In contrast, analysis by whole-life sensors, such as ultrasound sensors or capacitive gauges, can be very easily integrated into the pump electronics In order to be able to supply a solution for every requirement, Continental's frictionless MAPPS fuel level sensor provides a wear-free solution for applications in which no control electronics are yet available. However, as efficiency becomes a significant factor, ever more vehicles will be equipped with control electronics. This advance can be used, for example, to monitor pump wear. If the fed ratio drops due to ageing the electronics can adjust it and compensate for any drift. Diagnostics programs can proactive detect wear at the pump state or identify a locked fuel filter and issue a service alert. A further important possibility is for the on-board diagnostic (OBD II) to detect fuel tank leaks. At preset, this functions has to be realised separate whereas, in future, it could be more simply integrated into the fuel pump control electronics.(AF)