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Adaptive Cruise Control system utilising a Downhill Cruise Control System Disclosure Number: IPCOM000018994D
Publication Date: 2003-Aug-25
Document File: 9 page(s) / 116K

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US-6233515-B1: PATENT [+5]


An adaptive cruise control system for a vehicle comrising an adaptive cruise control computer program (distance regulation computer program) for calculating a desired speed for the vehicle and generate a speed request, which is used as an input parameter in a downhill cruise control system adapted to affect at least one auxiliary brake of the vehicle.

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Adaptive Cruise Control system utilising a Downhill Cruise Control System

The present invention relates to an ACC (Adaptive cruise control) system for a vehicle. The ACC system utilises a DCC (Downhill Cruise Control) system.

Background of the invention

Many road vehicles are today equipped with a CC (Cruise Control) system for keeping a substantially constant speed by automatically affecting an engine of the vehicle. The use of CC may reduce driver fatigue and improve comfort. However such a conventional CC system

is not suitable in dense traffic, since the speed of the vehicle must be manually affected when another vehicle, hereinafter called a target vehicle, having a lower speed appears in front of the vehicle with the CC system. Therefore ACC systems have been developed, which adapt the speed to the target vehicle.

An ACC system comprises a distance sensor arrangement equipped with e.g. a radar, a camera or infra-red distance measuring device. The ACC system also comprises a speed affecting part, which through the knowledge of inter alia the distance to the target vehicle affects the vehicle in such a way that the distance is not below a predetermined minimum distance to the target vehicle. When there is no target vehicle in front of the vehicle

comprising the ACC system, the vehicle is allowed to accelerate to the CC speed.

When a vehicle's speed is being maintained at a constant level by the CC system, the occurrence of a downhill slope may cause the vehicle to undesirably accelerate above the CC speed set by the driver even if the CC system stops the fuel supply to the engine. A speed in

excess of the desired CC speed in a downhill slope is particularly dangerous for heavy vehicles, such as trucks, due to a generally relatively longer braking distance compared to a lighter vehicle. The driver of the vehicle therefore has to deactivate the CC system (and the ACC system if activated), e.g. by applying wheel brakes and/or auxiliary brakes, such as a retarder. The deactivation of the CC system and if present, the ACC system, is of course

inconvenient for the driver. Therefore DCC (Downhill Cruise Control) systems have been developed, which when activated automatically applies at least an auxiliary brake when the vehicle speed exceeds a set speed by a certain amount, such as exceeding the CC speed with more than 3 km/h, in order to keep the CC speed also when driving downhill.







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Although ACC systems, such as an ACC system disclosed in US-6,076,622-A, are able to cause activation of the auxiliary brakes when regulating the distance between the vehicle and the target vehicle, they are not adapted to utilise a DCC system, which already may be present in the vehicle.

Therefore it is an object of the present invention to provide an ACC system that is able to utilise a DCC system, which can be used also as a stand-alone system without activation of the ACC system.

Through the invention described below,...