Tech Breakthroughs

Smart Materials

GM’s development of Smart Materials for automotive use is hailed by the company as a breakthrough event.

Actuators and sensors made from these materials have the potential to improve vehicle performance and fuel economy, and enable new comfort and convenience features. Significant benefits can be realized when smart materials are used to replace conventional motorized or hydraulic devices by reducing vehicle mass, component size and complexity and improving design flexibility, functionality and reliability.

Over the last two years, more than 140 patents have been issued or are pending on applications related to the use of shape memory alloys for automotive use. GM plans to integrate smart materials technology into its vehicles by 2010.

Shape memory alloys and polymers are examples of types of smart materials that can sense and respond to a stimulus that is introduced such as heat, stress, a magnetic field or electrical voltage. In response, they can change their shape, their dimensions, strength, transparency and stiffness. They “remember” their original shape and can return to it.

These capabilities open new possibilities for introducing movable vehicle features without mechanical, motorized or hydraulic devices that are used on vehicles today.

A few example applications include:

• Air dams, which are important to reducing aerodynamic drag at highway speeds are frequently damaged by low-speed impacts with parking bumpers, ramps and snow and ice. The “active” air dam, activated by shape memory alloy, can monitor vehicle speed, the use of 4-wheel drive and the presence of snow to intuitively lower or raise the dam to optimize aero drag.

• A grab handle that uses shape memory alloys to move into position through a combination of temperature-activated shape memory and stiffness changes. Shape memory alloys could eliminate the need for mechanical, motorized or hydraulic devices. For customer convenience, operation can be triggered by a button on the key fob, or by opening or closing the door.

• On-demand control of the airflow into the engine compartment uses a shape memory alloy-activated louver system. Reducing the cooling airflow into the engine compartment reduces aerodynamic drag. The result is improved aerodynamics and drag reduction, rapid warm-up during cold starts and noise reduction for diesel cold-starts.

Bosch Active Dynamics Control

The automotive industry is working intensively to network existing electronics systems in vehicles, as a basis for the development of new functions. One of these systems – Dynamic Wheel Torque Control by Brake (DWT-B) – is set to go into series production in the BMW X5. It was developed jointly by engineers at BMW and Bosch.

DWT-B improves a vehicle's agility by increasing engine torque and lightly braking the wheel on the inside of the bend at the back axle when the vehicle moves into a bend at speed. This increases the engine's motive force on the wheel on the outside of the bend. As a result, the vehicle is more agile and can corner more quickly with less steering effort – while maintaining the same high level of safety. The function is achieved by combining the engine management system with Bosch ESP®premium, which is also featured in the X5. All 5-series BMWs with four-wheel drive have been equipped with DWT-B since spring 2007.

DWT-B is the latest example of the kind of function that can be developed by combining ESP® with other vehicle systems that influence driving behaviour. Bosch uses the term Vehicle Dynamics Management (VDM) to describe all these functions.

Two other VDM functions – created by networking braking and steering features – contribute to improved driving safety. For example, in conjunction with the active steering made by the Bosch subsidiary ZF Lenksysteme, "Dynamic Steering Angle Control" (DSA) can stabilize the vehicle at a very early stage by correcting the steering angle independently as soon as the ESP® detects the onset of a skidding movement. "Dynamic Steering Torque Control" (DST) makes use of electrical power steering to vary the steering support provided by the system. In critical driving situations, this function guides the driver to intuitively choose the optimum steering movement by reinforcing or diminishing the steering support.

Lane Guidance System

TRW's Lane Departure Warning and Lane Guide Systems support the driver and assist in preventing unintentional lane departures.

Utilizing a forward-looking video camera that continuously monitors the vehicle's lane, the system can determine whether or not a driver is unintentionally drifting from their lane or the road. If the driver unintentionally begins to wander out of their lane, the system alerts the driver visually, audibly or by vibrating the steering wheel.

When integrated with TRW's Electrically Powered Steering, the system is also capable of providing a light steering input, helping the driver keep the vehicle within its lane.

If the driver uses the vehicle’s turn indicator, no warning is given and steering correction is not applied.

Intelligent Battery Monitoring

Strict regulations are limiting the amount of time trucks can idle to as little as three minutes in some US states and, as a result, trucks are relying more on back-up power to run heaters, air conditioners, entertainment and communication devices when drivers are at rest. Delphi Corp has developed a battery monitoring device to help manage the additional power load placed on the battery in this situation.

The Delphi Battery Monitoring Device combines an innovative IVT sensor with software that calculates the battery state of health and state of charge and will alert drivers to batteries that are in need of replacement or charging. It helps ensure optimal battery performance, making more electronics possible while ensuring sufficient power for starting the engine. When integrated into a vehicle as part of active battery management, the Delphi Battery Monitoring Device can also help improve fuel efficiency and extend battery life.

Delphi's Battery Monitoring Device features Local Interconnect Network (LIN) or Controller Area Network (CAN) interface for data and diagnostic communication. It is mounted on the negative battery post or in a pre-fuse box on the battery, and is designed for use in passenger and commercial vehicles beginning with model year 2010.

Oil Quality Sensor

Oil change intervals can be extended by around 25 percent by means of a special sensor. Researchers from Daimler AG have developed a practical system that allows them to monitor oil quality directly on board a vehicle. This helps reduce operating costs, especially in commercial vehicles.

The longer engine oil remains in use, the more it is susceptible to impurities. Its quality is impaired and it gradually loses its lubricative effect; this can even lead to engine damage. Timely oil changes are thus indispensable. However, this is offset by material costs (with up to 40 litres of oil in a truck's diesel engine) and loss of earnings due to downtime during maintenance. An oil change should therefore take place as early as necessary, but as late as possible.

Calculating the precise maximum service interval on the basis of mathematical models alone is difficult. The software must combine and assess various parameters: the engine oil temperature, the frequency with which the engine is started, mild or harsh conditions of use, and the particular circumstances of the vehicle's operation and environment.

In order to determine the ideal moment for the next servicing, the Daimler researchers therefore use a special sensor that provides clear readings. This sensor allows the engine oil to be monitored directly.

To evaluate the quality of the oil, its so-called permittivity is calculated by means of an AC potential applied between the interior and exterior pipes of the oil-filled sensor. This parameter is a measure of the extent to which the oil can transmit the applied electric field. If the engine oil is contaminated by water or soot particles, it polarizes to greater extent and its permittivity increases.

However, not all impurities can be registered with sufficient precision via the electric field. The researchers use viscosity as a further quality marker to detect any diesel fuel that may have found its way into the oil.

The Daimler researchers can also measure viscosity while the vehicle is in motion by observing the oil's side-to-side motion in the sump. The more slowly the oil moves, the higher its viscosity. This movement is registered by the oil sensor and the viscosity calculated on this basis.

One single sensor, and the intelligently processed information which is already available on board the vehicle, are sufficient to determine the various parameters of the engine oil. This onboard oil quality surveillance is currently being prepared for series application in commercial vehicles. The resulting precise calculation of due times for maintenance stops will allow oil change intervals to be extended by about one-quarter.