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Activation of Brake Lights in Case of an Ignition Failure

IP.com Disclosure Number: IPCOM000027224D
Publication Date: 2004-Apr-07
Document File: 4 page(s) / 88K

Publishing Venue

The IP.com Prior Art Database

Abstract

To ensure that the brake lights are lit up also in case of an ignition failure (e.g. X15/15), an engine control unit produces engine-run messages as long as the engine’s rotation speed exceeds a threshold value representing particular number of revolutions per minute. The engine-run messages are sent to a central control unit, which in response thereto transmits activation messages to relevant control units for the service brakes, and any other brake or retardation systems, as well as to a control unit for the brake lights. Thereby, the control units for the brakes, the retardation systems and the brake lights remain activated as long as the engine’s rotation speed exceeds the threshold value.

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Activation of Brake Lights in Case of an Ignition Failure

It is common that modern vehicles have a communication bus or a network for controlling various kinds of units and processes in the vehicles. For example, the Con­troller Area Network (CAN) standard specifies a widely used means of accomplishing such a network in trucks, busses and other ve­hicles. In general, these bus- or network solutions increase the flexibility and the overall efficiency of the vehicle. Typically, any control units that are connected to a network, such as CAN, receive a supply voltage from a common energy source, and are activated by means of an ignition key, a switch, or equivalent. This ignition controlled input represents a wake-up signal and is normally de­noted X15/15 in the vehicular industry.

Thus, in case of an interruption of or a disconnection from the ignition controlled input, the control units which are activated thereby run the risk of malfunctioning. Normally, the most critical functions, e.g. the brakes and other retardation systems, are provided with back-up resources, such that they may continue to be operable also in case of an ignition failure. However, it is important that not only the vehicle sub­jected to the failure may be brought safely to a stop, but also that other road-users are warned about the situation. There­fore it is desirable that at least the brake lights should continue to function even if the supply voltage to the control unit for the brake lights is inter­rupted/ broken, for instance because the ignition drops out.

In order to solve this problem, it is proposed that in case of an ignition failure (e.g. X15/15), an engine control unit produces engine-run messages as long as the engine’s rotation speed exceeds a threshold value representing particular number of revolu­tions per minute. I.e., the ignition has dropped out and the engine does not propel the vehicle, however the engine still rotates because of the force provided via the wheels and the transmission as a result of the vehicle’s kinetic energy.

The engine-run messages are sent to a central control unit, which in response thereto generates activa­tion mes­sa­ges. The activa­tion mes­sages, in turn, are sent to rele­vant control units for the service brakes, and any other brake or retardation sys­tems, as well as to a control unit for the brake lights. Thereby, the activation mes­sages ensure that the control units for the brakes, the retar­dation systems and the brake lights remain activated as long as the engine’s rota­tion speed exceeds the threshold value. Con­sequently, provided that the engine has a sufficient rota­tion speed, it is possible to reduce the vehicle’s speed by activating the brakes and/or any alternative retardation system (e.g. by using the vehicle’s brake pedal), even if the vehicle suffers from an ignition...