Moving Closer to By-Wire Braking

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    As the automotive industry continues the migration from mechanical to electric components and systems, the transformation in vehicle braking systems has rapidly advanced during the past few years beginning with ABS to traction control systems to electro-hydraulic brake systems (EHB).

    Delphi Corporation is now developing an advanced, lower cost alternative to EHB with its new hybrid braking system. This type of braking system utilizes a “smart” rear electric caliper with integral brake control function to control the braking force at the rear wheels. The conventional hydraulic front brakes, apply system and ABS front modulator are combined with the rear electric brake calipers. As a driver brakes, intensity is measured by a set of sensors, converted to a rear caliper apply command and communicated to the electric calipers. The front-to-rear brake balance is under software control and can be optimized for most effective braking force distribution.

    The hybrid braking system also includes the use of an integrated electric park brake that eliminates components and allows automakers to “plug-and-bolt” the rear brake corner during the assembly process without having to connect hydraulic pipes, hoses and parking brake cables. This also frees up space in the vehicle with the elimination of the parking brake lever or pedal in the passenger compartment.

    The benefits of hybrid braking include improved base brake response (calipers react more quickly); reduced brake pad drag; the ability to tune and independently control the rear calipers to improve front-to-rear brake balance. There will also be a reduction in overall mass because of the simplified rear rotor on some vehicles and the use of a single park brake system for different vehicle models. In terms of assembly, a number of components will be eliminated, reducing complexity and expediting assembly.

    Hybrid braking will also bring new functionality, eg a pushbutton parking brake as well as a dynamic parking brake function with ABS functionality. This is designed to help prevent the rear brakes from locking up if the parking brake is applied when the vehicle is moving. It will also be possible to have brake pad wear detection through the use of an integrated sensor in the electric calipers.

    As a major global supplier to leading automakers, Delphi will certainly be promoting this innovation to its customers and before long, motorists should be able to enjoy even better braking capabilities with hybrid braking.

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