Bosch has started selling a new version of its ESP brake control system which integrates sensors for yaw-rate measurement and lateral acceleration in the electronic control unit, a claimed world first.
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In the past, these sensors were installed separately in the interior of the vehicle, within a common housing and connected via the wiring harness to the electronic control unit.
“Integration significantly reduces both the space requirement in the vehicle and assembly work of car makers for the complete ESP system,” said Klaus Meder, head of Bosch’s chassis systems control division.
The first series application of the new technology is in the redesigned Seat Ibiza.
The electronic control unit is located in the engine compartment and is connected directly to the brake control system’s hydraulic modulator.
In order to integrate the sensors in the control unit, engineers had to overcome several technical challenges. They had to adapt them to cope with considerably higher ambient temperatures and also had to control the vibrations that occur when the brake control system intervenes from distorting the sensor output signals. The result was a vibration-reduced and balance-optimised, three-point installation of the hydraulic unit. This installation also ensures that driving on very poor roads will have no influence at all on the ESP function.
Another challenge was the orientation of the lateral-acceleration sensor. The sensor module, to date installed separately in the interior, must be placed precisely at right angles to the direction of travel. Due to the restricted space available, such a requirement for the installation of the unit in the engine compartment makes installation difficult.
Engineers have therefore integrated two acceleration sensors in the sensor element which measure precisely at right angles to each other. As a result, the hydraulic modulator, which must still be installed horizontally, can be positioned around its vertical axis as desired. The vehicle’s lateral acceleration can be calculated precisely, based on the known installation location and the signals from both acceleration sensors.
The sensor information now also enables measurement of the vehicle’s longitudinal acceleration and this value can be used for hill hold control and, when employed in vehicles with automatic transmissions, losses can be reduced in the torque converter, thus saving fuel.
