New generation of lambda sensors by Bosch

With the emission limits in exhaust legislation becoming ever stricter, exhaust sensors are becoming increasingly important. At the same time, manufacturers are becoming increasingly demanding with respect to sensors’ installation space, measurement accuracy, and robustness.



For this reason, Bosch is continuously driving the development of lambda sensors forward. It is now launching the LSF Xfour, the successor generation of the tried and tested LSF4.2 switching-type sensor. The new lambda sensor is smaller and more robust, and its measurement accuracy has been improved. In addition, it responds faster following a cold start.





Faster and more accurate, smaller and more robust

Compared with the LSF4.2, it takes half as much time to reach control mode following engine start. This significantly reduces the amount of time in which the engine’s emissions are uncontrolled. Combined with greater measurement accuracy, this will make it easier to comply with future exhaust standards. In addition, environmental impact is reduced. As overall length is shorter, the installation space needed for the entire sensor assembly has been significantly reduced, while increasing temperature resistance at the same time. As a result, there is greater choice when deciding where to install it in a passenger car’s exhaust tract. All variants of the sensor element can be equipped with a thermal shock protective coating as an option. This improves the sensor’s resistance to condensation in the exhaust tract following a cold start.



Multifunctional exhaust sensor, simple principle

Upstream of the catalytic converter, and occasionally downstream of it, the lambda sensor measures the oxygen content in the exhaust. This is an indicator of combustion quality. For one kilogramme of gasoline to be burned completely, roughly 14.7 kilogrammes of air are needed. The ratio of the mixture in the combustion chamber to the optimum mixture is known as lambda. Conventional gasoline combustion processes ideally operate at a setting of ‘lambda equals one.’ If lambda is smaller than one, the mixture is rich, with too little oxygen. If the ratio is greater than one, combustion is lean, with an excess of oxygen. This is the case with diesel engines, for example, or lean-burn gasoline engines. The switching-type sensor, which delivers an abrupt sensor signal when it detects a transition from a lean to a rich mixture, allows the optimum stoichiometric air-fuel mixture (? = 1) to be set precisely.



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Advanced Bosch technology for the efficient mobility of the future

“The internal-combustion engine will continue to play a major role in the future of personal mobility, and will contribute to the protection of the world’s climate and the conservation of our limited fossil-fuel reserves,” says Dr. Marcus Heyn, Executive Vice President Passenger Cars in the Bosch Diesel Systems division. The global market for new vehicles will grow from its present level of 71 million to 103 million in 2020. Of this figure, some 100 million vehicles will have an internal-combustion engine, according to external experts and market researchers at the automotive supplier. Automotive technology that helps to reduce the fuel consumption and CO2 emissions of gasoline and diesel engines will therefore gain special significance. Although highly efficient, by 2020 electric motors will play only a minor role in this reduction.



These days, many countries around the world have either agreed targets or legally binding limits for CO2 emissions, some of them ambitious. In 2009, the average new passenger car in Europe emitted 146 grams of CO2 per kilometer. The EU Commission has set its member states a target of 130 grams by 2013, and 95 grams by 2020. For 2025, experts are discussing a value of 70 grams of CO2 per kilometer for an average new vehicle. Under standard conditions, this would then mean consumption of roughly 3 liters of gasoline or 2.6 liters of diesel per 100 kilometers.





“However ambitious these targets may appear to be, they can be reached,” Heyn says. A major role here will be played by technology packages for more energy efficiency in the powertrain – packages that Bosch already has in its portfolio: hybrid concepts for the combination of internal-combustion engines and electric motors, downsizing concepts for eco­nomical gasoline and diesel engines, and energy-saving auxiliary units in the powertrain. In all, these Bosch packages allow a fuel saving of a good 30 percent to be achieved, with a corresponding reduction in CO2 – and this in both gasoline and diesel engines. Compared with the standard automotive technology in use today, consumption and CO2 emissions can be halved in total if additional measures taken by automakers are included. Even today, a number of especially economical vehicles already come close to the targets being discussed for 2020.



Downsizing, the key to saving fuel

In terms of the engine itself, the most effective measure is downsizing. Reducing displacement and the number of cylinders reduces friction losses and means less moving mass. An engine of this kind also has fewer thermal losses. Nonetheless, the aim is to achieve the same or higher engine per­formance.



An engine's performance can be maintained as long as more air is directed to it per combustion cycle than it is able to draw for itself. This is made possible by turbocharging, which provides the engine with the volume of air needed to ensure clean combustion. From the end of 2011, the joint venture Bosch Mahle Turbo Systems will produce modern turbocharger systems which are designed specifically for these new gasoline and diesel engine concepts for passenger cars and commercial vehicles. Bosch expects its joint venture to produce more than two million of these performance-optimized turbochargers in 2015.



In a gasoline engine, the condition for downsizing is direct injection. Engineers can use gasoline direct injection to cool the combustion cham­ber and at the same time achieve good scavenging without fuel losses in the gas-exchange cycle. The result is impressively high torque values even at low engine speed, something that was only possible with diesel engines before.



In diesel engines too, the potential of downsizing has still not been ex­hausted. As charge-air pressure through the turbocharger rises, Bosch engineers need to increase the injection pressure of the common-rail system as well. This makes sense in many ways. It means more diesel fuel can be injected in the same amount of time, which allows a better power yield. Alternatively, engine developers can reduce the diameter of the nozzle holes in the injectors while maintaining engine power. When com­bined with multiple pre- and post-injections, this improves mixture forma­tion in the combustion chamber, saves fuel, and leads to cleaner exhaust emissions. This is a particularly effective way of reducing nitrogen-oxide emissions.



Making auxiliary units more efficient and demand-driven

Increasingly, Bosch engineers are complementing all the technical meas­ures being applied directly to gasoline and diesel engines with more effi­cient auxiliary systems such as alternators or radiator fans. Additional CO2 improvements can be achieved by making systems demand-driven – so that they are only operated or used when they are really needed. Electric water pumps, electric power steering, and generators that recharge the battery primarily when coasting serve to improve the vehicle’s overall efficiency. One particularly effective example is the Bosch start-stop system. It stops the engine at a red light and restarts it reliably when the lights turn green. In the New European Driving Cycle, this achieves fuel savings of up to 5 percent, and as much as 8 percent in urban driving.



New technologies for more energy efficiency

Looking beyond the range of technologies that already exist for reducing fuel consumption and CO2 emissions, Bosch engineers are busy looking for ways to tap further savings potential – both in gasoline and in diesel en­gines. Here, they are studying measures such as combustion control using combustion-chamber pressure sensors. Or they are looking at variable valve control for diesel engines, not just for gasoline engines as is the case today. Work could also be done on transmissions to increase the efficiency of the automotive system, on energy recovery from exhaust heat, or on reducing the need for cooling.



Alternative fuels improve carbon footprint

Depending on regional circumstances, markets vary in the technical focus of their efforts to reduce CO2 emissions. In Brazil, for example, an impor­tant role is played by Bosch flex-fuel technology for gasoline engines. Sugar cane grown in the country is converted into ethanol, which serves as an alternative to fuels derived from crude oil. The fact that this fuel is made from renewable raw materials means it has a notable positive impact on carbon footprint. In the United States, more and more flex-fuel vehicles are being registered that can run on various gasoline-ethanol blends. Other countries and regions also take advantage of this eco-friendly effect by blending biogenic and fossil fuels – with blending levels of between five and 20 percent for both gasoline and diesel. In future, synthetic fuels based on organic waste materials will also gain in significance.



Fuel-saving technology pays off

Based on typical annual mileages for Europe and today's fuel prices there, a comparison of the fuel costs of the average car in 2010 with a car built in 2020 shows fuel cost savings over three years of operation of between 1,000 and 1,500 euros.



In other words, drivers’ operating costs are likely to be reduced by more than enough to cover the cost of all the extra technology they will have to buy in 2020 to make their cars more economical. If we consider a normal vehicle service life of some 12 years, this amounts to fuel savings of 4,000 to 6,000 euros and a reduction in CO2 emissions of between 6 and 11 metric tons.



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Bosch opening up new business areas in electromobility segment

An innovative supplier with a 125year history, Bosch is playing a decisive role in paving the way to electromobility. Technologies, components, and systems for electrical drives are now being developed under the double-armature brand, and in some cases already being manufactured. At the Bosch location in Hildesheim, for example, efficient electric motors are being made – for hybrid vehicles and, in a joint venture with Daimler, for electric vehicles. Series production of power electronics components has started in Reutlingen, and SB LiMotive, our joint venture with Samsung SDI, has been producing lithium-ion cells for electric vehicle batteries in Ulsan, South Korea, since 2010.



Some 400 million euros goes into the electrification of automotive drives each year, with 800 Bosch associates around the world working on this issue that is so crucial for the future of mobility. Out of a global total of some 103 million newly produced vehicles in 2020, Bosch expects to see some three million electric vehicles and plug-in hybrids, as well as roughly six million hybrid cars. From 2025, electrically driven vehicles will become an increasingly common sight on the world’s roads.





Bosch systems competence as a success factor

As we move toward the all-electric car, hybrid technology in its various forms is an important transitional technology. Bosch is currently focusing on two full hybrid designs that make it possible to travel short distances using purely electrical power: the parallel full hybrid and the axle-split hybrid. Both designs support internal-combustion engines in certain driving situations by way of a boost function. This enables the downsizing of spark-ignition and diesel engines. On the basis of present technology, this means that consumption and CO2 emissions can be reduced by between 25 and 30 percent, without any further changes to the engine itself. In the parallel full hybrid, the electric motor is integrated into the powertrain between the internal-combustion engine and the transmission. The axle-split hybrid features an internal-combustion engine on the front axle and an electrical drive for the rear axle. The positive side-effect of this configuration is four-wheel drive.



Bosch’s systems competence is the basis for controlling the complex interplay of internal-combustion engine, electric motor, and clutch, which results in additional benefits such as coasting and boosting. Coasting means that the internal-combustion engine is stopped and the vehicle coasts along without burning fuel. All safety and comfort systems continue to be fully operational. Boosting is when the internal-combustion engine is briefly supported by the electric motor when there is a need for extra power – when overtaking, for example. Bosch has been supplying the parallel full hybrid technology for the Porsche Cayenne and the Volkswagen Touareg since 2010, and now also for the Porsche Panamera. This year PSA will launch the Peugeot 3008 HYbrid4, the world’s first diesel hybrid, which features Bosch’s innovative axle-split hybrid technology. By 2013, Bosch will have started series production of core components such as electric motors, power electronics, and battery technology for 12 automakers in 20 different projects. Daimler AG and Robert Bosch GmbH are also working to set up a joint venture that will develop and manufacture electric motors. Called EM-motive GmbH, it will supply traction machines for Mercedes-Benz and smart electric vehicles from 2012. Bosch will be responsible for sales of these motors to other automakers.



Plug-in hybrid as a promising solution

The plug-in hybrid is an especially interesting approach. While its design is basically the same as the systems named above, a battery charger allows it to be recharged at any household power socket. In addition, its battery has a greater capacity. As a result, the distance the hybrid vehicle can travel all-electrically increases to some 40 kilometers per battery charge. In conurbations, this means that eco-friendly, all-electric, and locally zero-emission driving is possible for weeks on end. But at the same time, plug-in hybrids can cover long distances too with their internal-combustion engine – for instance when going on vacation.



Cost reduction as the key to success

Technically speaking, it is not a big step from the hybrid to the electric car. Cost-wise, however, there are still some major challenges to overcome. Bosch expects electric vehicles to cost around 45 percent more than comparable vehicles with internal-combustion engines in 2020. One of the most important questions in the further development and production of components for electrical drives is therefore how to reduce their system costs. Moreover, as volumes grow, prices drop, and as prices drop, acceptance grows. This is true of all projects in the field of electromobility: from e-bikes to hybrids and plug-in hybrids to the all-electric vehicle. This is why cost reduction is at the top of Bosch's to-do list.



SB LiMotive: development of the lithium-ion battery is progressing

Battery cost is a decisive factor for the success of electrical drives. SB LiMotive, the Bosch and Samsung SDI joint venture, has set itself the target of 350 euros per kilowatt-hour by 2015, and hopes to bring this down to 250 euros by 2020. Technically as well, lithium-ion cells are becoming increasingly mature. The key parameters, such as energy and power density, are being gradually improved, as are service life and cycle durability. By 2015, a 35 kWh battery made by SB LiMotive will have a range of 200 kilometers and a service life of at least 12 years, as demanded by the automotive industry. In the three years since it was founded, SB LiMotive has succeeded in gaining several major customers, and now has some 850 associates. For example, the company will supply lithium-ion cells for BMW’s i3 and 1 Series ActiveE. Fiat’s all-electric 500 EV will feature a complete SB LiMotive battery system. In addition, a U.S. consortium of Chrysler, GM, and Ford has awarded SB LiMotive a contract worth 8.4 million dollars to develop lithium-ion battery cells and systems. By 2015, SB LiMotive intends to boost annual cell production capacity in Ulsan, South Korea, to a good four gigawatt-hours – enough for some 180,000 electric vehicles. Since more and more European automakers are planning to work with SB LiMotive, a manufacturing facility is likely to be set up in Europe after 2013.



New business areas in the electromobility age

Electromobility holds out great potential for Bosch – not only for its traditional systems and components business, but also when it comes to opening up new business areas. One example is the establishment of charging infrastructure. Bosch Software Innovations GmbH is developing a software platform for charging electric vehicles as well as for reserving charge spots and billing for the energy used. Bosch Software Innovations charge spots interface both with the electricity provider’s grid and with the end user. Since June 2011, the software and charge spots have been in use in a pilot project in Singapore. Bosch Car Service repair shops and the Automotive Aftermarket division are also preparing for the coming market. Bosch supports car repair shops with diagnosis systems for hybrid vehicles and practical training. No other supplier in the field of electromobility has such a broad range of components, systems expertise, and services to offer. As electromobility only makes sense if the energy for it comes from renewable sources, Bosch has made energy conversion its task as well. The Bosch Solar Energy division is one of the major manufacturers of cells and modules for solar arrays. Its other activities in this market of the future include gearboxes for wind turbines and projects for marine power stations.



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New mid-range radar sensors for emergency braking in the middle and compact vehicle classes

In the coming years, driving will become even safer and more comfortable. Bosch is working toward this aim by improving existing assistance and safety systems while at the same time developing new features and improved sensors. "The high number of traffic accidents worldwide demonstrates the need for the best possible safety technology in the car," says Dr. Werner Struth, President of the Bosch Chassis Systems Control division, pointing to the results of a United Nations study. According to the United Nations, each year 1.3 million people die in road accidents worldwide, and some 50 million are injured. The annual number of road deaths could rise to 1.9 million in the next ten years - this increase will mainly be driven by growing traffic density in the emerging countries.



At Bosch, the findings of international accident research form the basis of the company's efforts to develop highly effective assistance and safety features. Skidding is often one of the causes of deadly accidents. ESP® provides a technical solution to this problem. Developed by Bosch, this electronic stability program helps prevent skidding. It went into series production for the first time in 1995, and has since become a mandatory standard feature in a growing number of countries.





Sensors that monitor a vehicle's surroundings and the networking of existing systems already form the basis for high-performing vehicle safety features. The current range of crash-avoidance products is rounded off by radar- ultrasound- and video-based functions such as the predictive emergency braking system, the side view assist, lane departure warning systems, and the night vision system.



In its efforts to develop new safety and assistance features, Bosch has a number of aims. On the one hand, the company is developing innovative products that offer tangible benefits and make driving even safer and more comfortable. In other words, these functions will make drivers’ lives easier. On the other hand, existing systems must become less expensive, as their cost will determine whether they can be employed in low-cost vehicles and in emerging countries. Only if safety technology is widely available can it make the contribution that is needed to injury-free and, ultimately, accident-free driving. Radar technology is one such development.



Smaller radar sensors with improved performance

Radar sensors have an especially long range, and allow distance and speed to be measured exactly. The first generation made by Bosch started off as part of ACC adaptive cruise control in 2000. Compared with this first generation, the current third generation of the long-range radar sensor (LLR3) is an improvement in every respect. Despite being about 60 percent smaller, its performance has been significantly improved. Moreover, the first-ever use of silicon-germanium technology in such a sensor reduces costs significantly. With a range of up to 250 meters and an aperture angle of up to 30 degrees, the LRR3 is the optimum sensor for high-performance ACC systems and predictive emergency braking systems in premium vehicles.



The radar sensor and the ESP® system form the basis of the emergency braking system. If the system detects an impending rear-end collision, it warns drivers and helps them brake. If the collision cannot be prevented, it automatically triggers full braking shortly before impact, making the accident considerably less severe. For dense inner-city traffic, Bosch has expanded the functional scope of the technology – the emergency braking system also supports drivers at speeds under 30 kilometers per hour. This technical solution will go into series production before the end of 2011.



In future, the new Bosch mid-range radar sensor will make such systems even more affordable. The sensor’s maximum range is 160 meters and its maximum aperture angle is 45 degrees. This means that emergency braking systems and ACC solutions can be used at speeds of around 150 kilo­meters per hour – which makes them feasible for use in the middle and compact classes. Installed in the rear, these features make it possible to fully monitor the blind spot. MRR will be launched at the end of 2012.



This new mid-range radar sensor operates like its long-range cousin in the 77 gigahertz frequency bandwidth. It is far superior to the 24 gigahertz variants available in the market, while costing roughly the same. It uses the frequency bandwidth that has been permanently allocated to automotive applications worldwide and is only roughly one-third the size of a typical 24 gigahertz sensor. Moreover, the 77 gigahertz version’s object separation is up to three times more accurate, and can measure speed and distance three to five times more accurately.



Video systems: an ideal supplement for radars

Used with radars, video sensors can provide a range of supplementary information. Merging the two types of sensor data gives rise to a very detailed “image” as an interpretation of the situation ahead of the vehicle. However, doing this calls for comprehensive expertise in all the relevant fields of sensor technology and image processing. The data can be used as the basis for powerful software algorithms.



The video sensor “understands” what is happening around the car. So the data can be used to detect not only vehicles and pedestrians, but also the direction in which they are moving. Moreover, the video data improve the ACC function. Movements across the line of travel can be detected sooner, so the system reacts more quickly, for example, when other vehicles overtake and cut into the driver’s lane ahead. The lane departure warning and lane keeping support features are fully based on video data analyses. Moreover, the video signals can also be used for adaptive light control as well as to detect traffic signals.



Accident prevention: drowsiness detection and motorcycle ABS

The dangerous phenomenon micro-sleep is usually preceded by a typical steering behavior. Bosch drowsiness detection continuously monitors the signals from the steering-angle sensor. If this behavior is detected, the system can warn drivers and urge them to take a break. Drowsiness detection can be produced at a low cost as a software function.



Apart from cars, motorcycles are frequently also involved in accidents. In many cases, the antilock braking system offers an effective remedy. Bosch launched a new, more compact generation in 2010. The basic version of the new ABS generation 9 for motorcycles weighs just 700 grams, which makes it the smallest system available. Its small size and reduced cost allow it to be used even in smaller motorcycles and scooters.



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New Bosch ABS for all motorcycle types

The old argument that antilock braking systems are too big and too heavy for motorbikes is no longer valid. “At 0.4 litres in size and 700 grams in weight, the current Bosch generation 9 is just over half the size and weight of the predecessor generation. This currently makes it the world's smallest motorcycle ABS,” says Tobias Fluck, a Bosch expert for motorcycle ABS. The company offers this modular system in various builds, ranging from a basic version to a premium version featuring an integrated electronic combined brake system. This means that the perfect solution is available for every motorbike, from the reasonably priced entry-level machine to the super-sports model. Generation 9 has been in series production since 2010, and currently features in models made by Kawasaki, BMW, Ducati, and KTM.

At present, if motorcyclists have to brake as quickly as possible in a critical situation, they face a difficult task. On most motorbikes, they have to first of all use the hand and foot brakes separately to control the braking pressure for front and rear wheels. Then they have to prevent the wheels locking up at all costs. The findings of a Bosch study based on GIDAS, the German database of accident statistics, therefore come as no surprise: 47 percent of motorcycle accidents are caused by wrong and hesitant braking. The antilock braking system solves this problem, allowing safe braking by preventing the wheels from locking up. This can both prevent a fall and significantly reduce braking distance. Up to now, however, ABS systems are a rare sight on motorcycles. Where cars have been rolling off the production lines in Europe with ABS as a standard feature since 2004, only 16 percent of newly manufactured motorbikes featured ABS in 2010.



The compact Bosch system is available in three versions
The previous ABS systems of all suppliers were based on passenger-car technology, and were thus comparatively large. While they could be installed in larger machines, this was often not possible in small motorcycles. So while the new generation of Bosch brake control systems was being developed for passenger cars, the engineers at the Bosch Engineering Centre in Japan came up with an ABS series especially for motorbikes. The result of their work was the ABS generation 9, only half the size of its predecessor. It is also modular, allowing variants to be produced for different ranges of functions, and its design is cost-effective, which is important if it is to be used widely in all motorcycles with hydraulic brake systems.

Despite its compact construction, the ABS 9 base offers full antilock protection. Moreover, sudden changes in road surface, caused for example by grit or patches of oil, no longer present cause for alarm. ABS allows even inexperienced riders to brake safely. The ABS 9 plus variant is especially suitable for powerful machines. Because it uses an additional pressure sensor, it takes effect even when pressure is being built up during emergency braking This specifically prevents the rear wheel rising, and thus heads off the risk of flipping over.

ABS 9 enhanced, the most powerful version, offers the additional eCBS function. eCBS stands for electronic combined brake system. What this means is a novel combination of front and rear brake. In this integrated version, it is enough for the rider to operate just one of the two brakes – front or rear: ABS 9 enhanced automatically applies the second brake without the rider having to apply more pressure and without changing braking strength. The motorbike can thus brake safely both on wet surfaces and on dry surfaces with a good grip.

Even now, ABS 9 enhanced can help to a moderate degree to stabilize righting moment and banking when braking in an inclined riding position. Moreover, even more functions can be added to the Bosch ABS with eCBS. Successful trials are currently being performed with versions that modulate braking pressure so effectively, even in curves, that the typical motorcycle accident as a result of over-braking the front or rear wheel can be largely ruled out even here. And a controlled intervention in the engine management system is also possible. This opens up the possibility of new functions such as traction control and hill-hold control.


ABS for all motorized two-wheelers from 2017
In 2009, more than 5,000 motorcyclists were killed on Europe's roads alone. According to the European Transport Safety Council (ETSC), the danger of a fatal accident, for the same distance travelled, is 18 times higher for motorcyclists than for car drivers. And according to many scientific studies, ABS is the system with the greatest safety gain for motorcycles. For example, a study presented by Vägverket, the Swedish highways authority, in 2009 confirms that 38 percent of all accidents involving personal injury and 48 percent of all serious and fatal accidents could be prevented with the help of ABS. A Bosch study based on data from GIDAS, the major German accident statistics database, concludes that a quarter of all accidents with injuries and fatalities could be prevented if ABS was standard equipment. A further one-third of all accidents with injuries and fatalities could at least be mitigated by the antilock system. In 2010, findings such as these were enough to persuade the EU Commission to propose making ABS mandatory for motorized two-wheelers from 2017.

A study of the benefits of ABS conducted by the European Commission shows that more than 5,000 lives could be saved over the next ten years alone if ABS were made mandatory. A decision is expected to be taken this year. But for the emerging markets in Asia and South America as well, ABS promises a significant improvement in road safety. The condition for its use on a wide scale is a hydraulic brake system. In all markets, this standard is becoming more and more established.

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