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Fuel Cells

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 Cell

Others.. 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.          

Vehicle Safety


  A high-speed camera is used to capture visual information during crash tests.

Image courtesy & © Volvo Car Corporation




Safety is an increasingly significant element of vehicle design. The earliest automotive legislation related to safety and still accounts for the bulk of all vehicle regulation. Today, there are two main forces driving improvements in vehicle safety. The first is the consumer, the car buyer who wants a vehicle that will protect them and their family in the event of an accident. The second is the legislature, the organisation responsible for laws and regulations; they not only want improvements in safety for occupants but also for third parties such as pedestrians and other road users. With sales of premium brands increasing as value brands decline, safety is often a large part of the premium product. In addition to Volvo, most brands now market their safety credentials to the consumer; not least Renault who have invested substantial resources in achieving high EuroNCAP ratings for the reasons outlined above. Safety is a core component of vehicle design. Volvo how their technology has helped in the EuroNCAP tests Principles Some basic concepts in safety design for vehicles.


Passenger Safety For decades, vehicle safety has centred around the occupant(s). This section takes a look at the significant aspects of passenger safety.


Pedestrian Safety A relatively new field, with much yet to be discovered. This section covers the new design approaches to dealing with pedestrian-vehicle impacts.   Technologies Simple and complex products and systems work together to make up the full portfolio of safety elements on a car. In this section we explore the technologies that are key to safety improvements from crash



Resources SAVE-U – Sensors and system Architecture for VulnerablE road Users      

Vehicle Safety


  A high-speed camera is used to capture visual information during crash tests.

Image courtesy & © Volvo Car Corporation




Safety is an increasingly significant element of vehicle design. The earliest automotive legislation related to safety and still accounts for the bulk of all vehicle regulation. Today, there are two main forces driving improvements in vehicle safety. The first is the consumer, the car buyer who wants a vehicle that will protect them and their family in the event of an accident. The second is the legislature, the organisation responsible for laws and regulations; they not only want improvements in safety for occupants but also for third parties such as pedestrians and other road users. With sales of premium brands increasing as value brands decline, safety is often a large part of the premium product. In addition to Volvo, most brands now market their safety credentials to the consumer; not least Renault who have invested substantial resources in achieving high EuroNCAP ratings for the reasons outlined above. Safety is a core component of vehicle design. Volvo how their technology has helped in the EuroNCAP tests Principles Some basic concepts in safety design for vehicles.


Passenger Safety For decades, vehicle safety has centred around the occupant(s). This section takes a look at the significant aspects of passenger safety.


Pedestrian Safety A relatively new field, with much yet to be discovered. This section covers the new design approaches to dealing with pedestrian-vehicle impacts.   Technologies Simple and complex products and systems work together to make up the full portfolio of safety elements on a car. In this section we explore the technologies that are key to safety improvements from crash



Resources SAVE-U – Sensors and system Architecture for VulnerablE road Users      

Recycling

  Recycling vehicles and their components is a serious concern to manufacturers. (More information on the European End-of-Life Vehicle Directive.) The core materials used in most vehicles today are quite straight-forward to recycle. This page takes a look at recycling considerations within the automotive industry.   Steel Steel is the most common material in vehicle production. It is relatively easy to reclaim and recycle. Two-thirds of steel used in US car manufacturing is recycled (source: Steel Recycling Institute); the remainder is new. Aside from environmental considerations, it is economically preferable to recycle due the large costs in obtaining steel from ore. New steel is generally used when recycled supply cannot meet demand.


Aluminium Aluminium is still a small material by volume in car production. Obtaining Aluminium from Bauxite (ore) is an expensive process that requires considerable electric current; it is for this reason that Aluminium was once a semi-precious metal and has only (relatively) recently entered mainstream use. Recycling is quite straightforward with aluminium and, like steel, is economically preferable.   Plastics Plastics come in two types – Thermosets and Thermoplastics. Thermosets are made up of strong bonds that are created with heat and subsequently do not melt with heat. This means that they cannot be reused and are either scrapped when finished with or ground down to make a filler material for something else. Thermosets are being phased out from car production as and when possible. Thermoplastics, on the other hand, become fluid (plastic) with heat. This means they can be melted down and remoulded or added to new material. This characteristic makes them ideal for recycling on cars; it is necessary however, to match the properties of Thermoplastics carefully to their role on a vehicle; polypropylene and nylon are often used for the demanding conditions of the engine bay.   Precious Metals Electronic components and circuitry are often made up of thousands of complex elements which are almost impossible to seprate and recycle. Within this componentry there is a variety of toxic metals such as lead and cadmium in circuit boards, mercury in switches and flat screens and brominated flame retardants on printed circuit boards, cables and plastic casing.

When dumped, these metals contribute to a range of types of pollution with serious consequences to human health and the environment. As increasing amounts of electronics feature in cars, this will become of greater concern. Currently,            

Mercedes Necar Hydrogen Fuel Cell Car

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.

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.
Images courtesy & © DaimlerChrysler

Pedal Box Design / Drive-by-Wire



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.





   

Automotive Design

Welcome to the design section of Car Design Online. This area includes information on most of the pre-production elements of automotive design. These include the creative elements of vehicle development, such as sketching and modelling, as well as other important considerations, namely aerodynamics and ergonomics.

Aerodynamics

In this section we take a look at the science of aerodynamics and how manufacturers use CAD and wind-tunnel testing to perfect new vehicles.

Ergonomics

An increasingly important aspect of automotive design, this section on ergonomics and anthropometrics looks at design for human form and behaviour.

Modelling

Whether virtual or actual, realising a design in 3D has always been a critical element of vehicle development. From clay to CAD, we look at the different methods and practices.

Sketching

From a designer’s initial idea to fully resolved renderings; we take a look at how ideas are realised in 2D.

Aerodynamics

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.

Pressure Sensitive PaintAerodynamic work on the 1960s Ford GT programmeWind tunnel testing for modern vehicles

Automotive Production



Welcome to the automotive section of Car Design Online. This area addresses the demands and requirements of design for manufacture and covers key considerations such as materials, processes and production feasibility.




 


Materials A look at some of the key materials used in automotive production including staples such as steel and more advanced composites such as carbon fibre. Manufacturing Processes From body-in-white to road-going vehicle, this section looks at the processes used in automotive manufacturing.

Global Production Figures

Car sales/production figures by manufacturer




The Mercedes SLR McLaren uses the latest carbon fibre technology Resources Siemens Automotive Production Portal

The Welding Institute