With the ever increasing significance of performance in impact, car manufacturers are looking carefully at traditional elements of vehicles and their specific behaviour under crash conditions. One very significant element is the pedal box. Where the pedals are held and pivoted, a rigid structure is typically required; in impact, the pedal box can be forced in on a driver’s lower leg and feet leading to significant injury. Several ways to resolve this have been tried or are under consideration including alternative pivot points, collapsible pedal boxes, breakable pedal connections and more complex arrangements that bypass direct mechanical connections. In an article for MIRA New Technology, Fernando Burguera of Batz, S. Coop, explains how designing for EuroNCAP is becoming a practicable industry standard and how manufacturers are looking to suppliers to help them tackle crash performance component by component. Drawing upon the current EuroNCAP testing procedures and anticipating ongoing raising of the bar, Batz, S. Coop. built a list of specifications in order to design new pedal box systems: Zero forward movement (possibly some backward movement) after collision No entrapment of the foot Immediate activation No accidental activation Functionality after impact; it may still be necessary to brake even after impact Vehicle independent; the system should be self-contained The full article can be found here. Drive-by-Wire A more costly and complex solution to the issue of pedal box crash performance is to attempt to remove significant mechanical components and supporting structure. This is done by replacing direct mechanical connections with electronics which act as a proxy between the driver’s input and the actuation of driving controls, namely accelerator, brakes and clutch. Any such system involves the sensing of user input and consequently relaying that to servos and actuators. The benefits include the simplification of structure in the pedal area and the possibility of computer correction for control errors. Detrimental factors include a substantial increase in component cost and complexity including increased manufacturing and maintenence cost. An example of a proxy control is the Valeo Clutch-by-Wire. The unit replaces the mechanical link between clutch and pedal with an electrical clutch actuator, an electric clutch pedal and an electronic control unit (ECU). A pedal sensor measures the position of the clutch pedal and transmits this information to the ECU which also receives information about car behavior. The ECU in turn controls the clutch actuator and depending upon the driver’s wishes, the system can not only correct driver mis-operations but offer complete clutch automation. The system is designed to require lower stroke and effort to the pedal and improves pedal feel with “virtual” resistance to foot pressure. More compact than a conventional clutch actuation, the Clutch-by-Wire system improves driver crash protection since it enables an optimized, less intrusive, pedal box design. |
Archives for : Technology
| Basic computer systems have been used in cars for several years. Most recently, they have been used to offer more advanced on-board information systems. Central processors have for some time been used to control engine management – ensuring smooth running, good fuel efficiency and performance. They have, however, performed relatively simple tasks and are not safety critical. More advanced use of information technology in cars will lead to an increase in user-orientated systems. Systems will continue to be developed to control and manage the mechanical elements of a vehicle – such as engine, suspension and braking – but the most noticeable changes will take place inside. Displays & Interfaces One area of vehicle intelligence that has already raised its head above the parapet is that of user interfaces. It is now possible to display all the information a driver or occupant may want without the use of three-dimensional analogue displays. Above and beyond that, it is now possible to cater the information that is displayed to the particular preferences of a user and to further vary that according to changing conditions – such as traffic, weather, time of day etc. It is envisaged that information relating to specific traffic conditions could be relayed to a driver in motion. Such systems would not only indicate congestion problems but perhaps warn of large numbers of pedestrians, accident black spots, approaching emergency vehicles – even opportunities for refuelling should the tank be empty. Importantly for designers, the manipulation of displays and interfaces will allow the use of new aesthetic concepts, the simplification of dashboard forms and the ability to incorporate a large number of controls into small areas. Design considerations Controls can take the form of touch sensitive displays, allowing greater use of smooth surfaces. Using multi-mode and menu systems, digital displays can eliminate the need for dashboard space for every control. Using technologies such as E-Ink, it will be possible to place displays and controls over entire surfaces; this offers opportunities for 2D graphic aesthetics (like computer screensavers) to be developed as well as the creation of large interactive work surfaces. Environmental Interaction Many location based information systems are already available and use satellite positioning coupled with pre-stored data about certain locations as well as live traffic information. With the increase of wireless technology, and ultimately its ubiquitous presence, it will be possible for a vehicle to simply collect (and pass on) information as it moves through different areas. Recognition & Flexibility |
Fuel cells are largely envisaged as the most likely successor to the internal combusion engine (ICE) and are at advanced stages of development for use in motor vehicles. Fuel cells are not restricted solely to transport and can be used for power generation in a range of contexts. It is however, transport that is believed to hold some of the greatest possibilities for the technology.  Mercedes-Benz A-Class NeCAR Fuel Cell Vehicle Background and History The fuel cell was invented by Welshman Sir William Grove in 1839. It was his ‘gas voltaic battery’ that laid out the principles for modern fuel cells. Grove new that passing a current through water caused the separation of water into hydrogen and oxygen and hypothesised that the reaction could be reversed – thus creating an electric current. From his experiments, he created the first fuel cell. The term ‘fuel cell’ only came later in 1889 with Charles Langer and Ludwig Mond’s attempts to produce a working device. In the 1960s, NASA used fuel cell technology to create electricity for spacecraft. Further development took place in the ’70s but it wasn’t until the 1980s that testing began in the automotive industry. In the mid ’90s, automotive prototypes were finally coming closer to practical use but the size of componentry was still a serious problem. Now, the size of fuel cell components has become manageable and testing is in advance stages. Ballard Fuel Cell Timeline The Principles of Fuel Cells In the most basic sense, a fuel cell works in a similar way to a battery, changing chemicals from one form to another, generating an electric current as a by-product. The key difference is that whilst batteries hold energy to be released, fuel cells can generate energy only whilst they are supplied with fuel and air. The fuel used is typically hydrogen but can take other forms. Unlike the combustion engine, a fuel cell has no moving parts making it far more efficient. Power is output as electric current which is passed to electric motors which in turn drive the vehicle. A combustion engine can actually only ever transfer a fraction of its input energy into motion; with substantial losses due to converting heat into mechanical energy. Toyota have stated that their conventional petrol engine offers a ‘tank-to-wheel’ ratio of 16% compared to their fuel cell vehicle which offers 48%. In terms of vehicle design, fuel cells can now be packaged within relatively standard proportions. The following components must be incorporated: Fuel cell stack Battery Electric motor(s) – depending upon your choice of drive configuration Hydrogen tank Electronic contol unit. The Main Types of Fuel Cell Proton Exchange Membrane (PEM)PEM fuel cells are relatively small with a good power generation ratio for their size. These systems use a solid polymer membrane as the electrolyte and operate at low temperatures. The solid electrolyte means simpler production and longer life whilst low operating temperatures allow faster start-up and power increase responses. Proton exchange membrane fuel cells are the choice for automotive applications due to the favourable performance they offer in a small package. All current automotive fuel cells use the PEM system. More details on the PEM Fuel CellOthers.. Alkaline Alkaline systems need pure oxygen and hydrogen to work which makes them less versatile than other types of fuel cell. Phosphoric Acid Common for use in industrial power generation, they are typically used in static applications. With their high operating temperature, corrosive electrolyte and complex system, they are not appropriate for automotive roles. Molten Carbonate These systems are highly complex and use a molten electrolyte. This means the system operates at very high temperatures; this allows the process to take place without a fuel processor but it is only used in wholesale energy production applications. Solid Oxide These systems run at extremely high temperatures and can operate with far less pure fuels than other systems; their overall operation is relatively simple. Planned use as very large static power stations. |
Mercedes-Benz (DaimlerChrysler) believe that fuel cell vehicles offer the best options for sustainable vehicle propulsion. Since the 1990s, DaimlerChrysler and its affiliated companies have developed and demonstrated hydrogen and fuel cell technology for automotive applications. Researchers and engineers have been working toward practical implementations of this technology since the early nineties. DaimlerChrysler presented its first fuel cell concept study for the NECAR series in 1994. Since then, 20 different vehicle prototypes with fuel cell drives have been developed and tested. The vehicles range from the Mercedes-Benz A-Class and the Jeep Commander to the NEBUS.
In 2001, DaimlerChrysler presented the “Natrium†(the Latin word for sodium), which demonstrated an innovative and unconventional method for storing hydrogen: on board a minivan, hydrogen was generated directly from a white salt – sodium borohydride.
In May 2002, the NECAR 5, running on methanol travelled 3000 miles across the US to prove the technology to the World at large. Practical use came in 2004 when the first F-cell, based on the Mercedes-Benz A-Class began use under normal conditions around the world. Additionally, bus and commercial vehicle fuel cell vehicles are in operation in many countries.
The A-Class lent itself well to use as a fuel cell vehicle. It is believed that the A-Class was originally intended to house electric propulsion and was hence designed with space below the passengers. This space is utilised in the NECAR for the fuel cell system components – especially energy storage in the form of hydrogen tanks and batteries.
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| Battery technology continues to develop and improve leading to increasing efficiencies and space savings. Future generations of fuel cell vehicles are likely to use smaller battery packs, making packaging simpler. However, hydrogen is already stored in compressed form and offers very little room for space saving in the future. Instead, improvements in the fuel cell process will be the key to reducing the need for fuel and hence the need for fuel storage. |
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| Images courtesy & © DaimlerChrysler |
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| Image courtesy & © Ford Motor Company |
Aerodynamics is a highly refined science that vies for position with other key vehicle design considerations such as styling and ergonomics. It’s importance with respect to the operating efficiencies of a vehicle is undisputed but manufacturers must steer a balanced path between the push an pull of the many other aspects of a car necessary to sell it to the consumer.
Aerodynamics started life as much as an art as a science. Early experiments used fish as the inspiration. Their sleek form was considered important to facilitate fast movement, but the precise details were not yet understood and developments were largely based on trial and error. It was as a result of this approach that the ‘teardrop’ form was conceived.
Aerodynamic Considerations
A summary of key principles and basic rules to follow in order to improve aerodynamic efficiency when designing a vehicle.