BMW EfficientDynamics in Detail

Page 1: Overview
Page 2: World first direct gasoline injection
Page 3: EfficientDynamics in a new dimension
Page 4: The highest standard

Innovation in detail for EfficientDynamics of the highest standard:

Reduction of fuel consumption and emissions in BMW’s new four-cylinder models.

The new four-cylinder power units now being introduced by BMW offer a supreme standard of EfficientDynamics in particularly compact dimensions. This applies both to the latest generation of diesel engines and to the new petrol engines, each with four cylinders. In both categories BMW’s latest power units set the standard in terms of power and performance combined with superior economy.

Regardless of whether petrol or diesel as well as the category of power and performance chosen, all drivers of a four-cylinder BMW thus benefit from BMW’s significant progress in engine development defining the strategy of EfficientDynamics. In comparison with their respective predecessors, all new-generation four-cylinders offer lower weight, more power, greater fuel economy, and optimised emissions.

In addition to the various improvements and modifications within the engine – ranging from the reduction of internal friction and the redesigned combustion chambers through the optimisation of the combustion process, air flow and turbocharging all the way to High Precision Injection as a lean burn direct injection concept with the petrol engines and, respectively, the latest-generation common rail fuel injection on the diesel engines – innovations specific to the vehicle ensure further enhancement of all-round economy in every respect.

These innovations thus help in various ways to convert the power developed by the engines even more efficiently into genuine driving dynamics.
The engines develop their superior qualities under all kinds of loads and operating conditions, ensuring that the higher standard of efficiency offered in all BMW cars powered by these new four-cylinders is reflected in everyday motoring by a measurable reduction of fuel consumption.

Auto Start Stop function: zero fuel consumption while idling.

To avoid the consumption of fuel during long idling periods at road junctions or in traffic jams, BMW’s new four-cylinder petrol and diesel engines with a manual gearbox feature an Auto Start Stop function. This function is activated as soon as the car comes to a standstill, the driver shifts to neutral and takes his foot off the clutch pedal. Then, to go on driving, all the driver has to do is press down the clutch to start the engine without delay. Both the electric starter and the starter battery are specifically laid out for the extra burden of such additional starting processes.

The Auto Start Stop function is activated automatically every time the driver starts the engine and is switched off automatically once the engine oil has reached the operating temperature required. For reasons of safety and motoring comfort, there is no automatic deactivation under certain conditions, for example when the battery is almost flat or at very high (more than 30° Celsius) or very low (less than 3° Celsius) outside temperatures. When coming to a brief halt, the engine will also go on running as long as the temperature inside the car has not yet reached the level preselected on the air conditioning or if heater power is required to remove ice or surface mist from the windscreen. And last but not least, the driver has the option to de-activate the Auto Start Stop function at any time simply by pressing a button.

With this function being very comfortable and convenient, the driver will get used to such automatic engine control very quickly indeed. The engine restarts very smoothly and spontaneously as soon as required, since the control unit “remembers” the position of the crankshaft at precisely the point when the engine was switched off, activating the ignition and fuel injection without the slightest delay. Building up pressure in the fuel injection system does not take any extra time, either, since the pressure already generated in the fuel pipe is kept unchanged while the vehicle is at a halt.

To optimise the efficiency of the system also while driving, the Auto Start Stop function is combined with a gearshift point indicator, the engine’s electronic “brain” calculating the optimum point for shifting up gears in the interest of maximum fuel economy, as a function of driving conditions. So the gearshift indicator – an arrow symbol lighting up and specifying the optimum gear – in the instrument cluster “tells” the driver to shift gears at exactly the right time.

Brake Energy Regeneration for efficient electric power supply.

Intelligent management of the flow of energy in generating, storing and using electric power on board the car makes a further contribution to the reduction of fuel consumption and CO2 emissions. Brake Energy Regeneration moves the process of converting primary energy to electric power to the overrun and brake application phases. This reduces the load acting on the alternator while the car is accelerating and driving under power, with the on-board electric network being supplied with electricity exclusively by the battery under such conditions. Clearly, this means more engine power for accelerating and driving dynamically. The alternator will only be reactivated when the engine enters the overrun mode.

Electric power is therefore generated primarily when the driver applies the brakes, intelligent alternator control also considering the current charge level of the battery. So once battery capacity drops below a defined minimum level, the alternator will generate and supply electric current regardless of driving conditions.

With such intelligent control also increasing the number of charge cycles, the alternator control system is combined with modern AGM (absorbent glass mat) batteries able to withstand far higher loads than conventional lead acid batteries. In an AGM battery, acid is kept in micro-glass-fibre mats between the layers of lead, maintaining its energy storage capacity for a long time even when recharged and discharged frequently.

Saving energy: steering assistance only when really required.

BMW models driven by the new four-cylinder power units also come with BMW’s new EPS Electrical Power Steering. EPS provides electrohydraulic steering assistance, with the hydraulic steering assistance pump being driven by a small electric motor.

While on hydraulic power steering the pump driven by the combustion engine generates pressure permanently and therefore consumes energy all the time even when no power assistance is required, EPS operates independently of the engine and is therefore very efficient, the pump building up pressure only when steering assistance is actually needed. Compared with a conventional steering system, this means a significant reduction of fuel consumption.

Operation of the air conditioning in BMW’s new four-cylinder models is also tailored more precisely to the actual needs and requirements of the occupants, serving again to reduce the consumption of energy. For as long as there is no need to cool the interior, the system is able to save energy in the interest of enhanced economy. A conventional climate compressor, through its operating principle alone, is subject to a permanent loss of power even when the air conditioning is not in use. The compressor on BMW’s new four-cylinder power unit, in turn, may be separated completely from the belt drive by a magnetic clutch, thus continuing to minimise the loss of power as soon as the air conditioning has been deactivated.

Ancillary units controlled and operated on demand.

BMW’s engineers save additional energy on the new four-cylinder petrol engines by activating ancillary units such as the coolant, fuel and oil pumps only when really required. Controlled as a function of temperature, the electric coolant pump operates only when really needed, thus helping the engine achieve a higher level of all-round efficiency. The electric water pump, in turn, adjusts the amount and flow of water to the engine’s actual cooling requirements, regardless of engine speed, reducing the drive power required for the pump by up to 90 per cent or approximately 200 Watt.

A further point is that there is no flow of coolant when starting the engine cold, enabling the engine to reach its operating temperature more quickly. And last but not least, this technology offers additional customer benefits through the option to use the residual heat in the coolant even when the engine is at a standstill in order to warm up the interior.

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