· Signal processing in the system control unit

· Variable design provides wide scope of applications

Bosch has extended its steering-angle sensor offering to include a new cost-effective model. The LWS6 meets all standard requirements of today's safety and comfort systems, and is therefore especially suitable for ESP® applications in compact class vehicles and classes further down the scale. The signals from the LWS6 can also be used, however, for systems such as electro-hydraulic power steering or ACC adaptive cruise control. The sensor recently went into series production.

Steering-angle sensors measure the steering wheel's actual position, the value which an increasing number of systems use to determine the direction the driver wants the vehicle to take. The new LWS6 measures relatively over an unlimited measuring range. Its typical steering-angle signal resolution is 1.5 degrees. The LWS5 steering-angle sensor, which is based on GMR (giant magneto resistance) technology, measures absolutely. The LWS6 steering-angle sensor, by contrast, uses the Hall effect. For this purpose, a multipole magnet is fixed to the steering column. Hall elements detect changes in the sensor's magnetic field without contacts and without gear wheels. As two or more Hall elements are used, any rotary motion generates square-wave signals, which show a certain phase shift relative to each other. These square-wave signals are transmitted directly to the control unit, thus ruling out any need for evaluation logic in the LWS6. Processing of the sensor signals is done by the system control unit, which calculates the position, rotation direction, and rotation speed of the steering wheel.

The control unit also validates the sensor output signals and detects short-circuits, for example. Moreover, due to the incremental measuring principle of the LWS6, it no longer has to be calibrated by the automakers. Thanks to the new concept used in the LWS6, Bosch has reduced the cost, not only of the sensor, but also of the system as a whole – and has therefore also made a further contribution to achieving the goal of “safety for everyone”.

As there is no mechanical link between the Hall measuring elements and the magnetic hub, the sensor is wear-free. Unlike optical sensors, the magnetic measuring principle makes the LWS6 resistant to contaminants, such as dust, which find their way into the housing over the course of the device's service life. As with the LWS5, the LWS6 does not require stand-by current when the vehicle is parked. Customer-specific designs offer extensive adaptation options for a variable steering column installation or integration into the switch unit. The new Bosch sensor has been developed in accordance with current environmental requirements and is made of lead-free components.

The Bosch Group is a leading global supplier of technology and services. In the areas of automotive and industrial technology, consumer goods, and building technology, some 275,000 associates generated sales of 38.2 billion euros in fiscal 2009. The Bosch Group comprises Robert Bosch GmbH and its more than 300 subsidiaries and regional companies in over 60 countries. If its sales and service partners are included, then Bosch is represented in roughly 150 countries. This worldwide development, manufacturing, and sales network is the foundation for growth. Each year, Bosch spends more than 3.5 billion euros for research and development, and applies for some 3,800 patents worldwide. With all its products and services, Bosch enhances the quality of life by providing solutions which are both innovative and beneficial. The company was set up in Stuttgart in 1886 by Robert Bosch (1861-1942) as “Workshop for Precision Mechanics and Electrical Engineering.” The special ownership structure of Robert Bosch GmbH guarantees the entrepreneurial freedom of the Bosch Group, making it possible for the company to plan over the long term and to undertake significant up-front investments in the safeguarding of its future. Ninety-two percent of the share capital of Robert Bosch GmbH is held by Robert Bosch Stiftung GmbH, a charitable foundation. The majority of voting rights are held by Robert Bosch Industrietreuhand KG, an industrial trust. The entrepreneurial ownership functions are carried out by the trust. The remaining shares are held by the Bosch family and by Robert Bosch GmbH. Additional information can be accessed at www.bosch.com.

PI6933 - May 2010