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Warning system for a reduced braking torque from an auxiliary brake in a vehicle

IP.com Disclosure Number: IPCOM000019727D
Publication Date: 2003-Sep-26
Document File: 9 page(s) / 104K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention relates to a method for showing a driver of a vehicle that at least one auxiliary brake is activated and warning the driver when the at least one auxiliary brake is not able to produce a predetermined braking effect/torque. The method comprises the steps of: determining a braking torque provided by the at least one auxiliary brake, determining if a maximum allowed braking torque has to be reduced in order to avoid damage on the vehicle, activating a first kind of light in an indicator visible to the driver of the vehicle if the braking torque is applied and the maximum braking torque is not reduced, and activating a second kind of light in the indicator if the braking torque is applied and the maximum allowed braking torque is reduced.

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Warning system for a reduced braking torque from an auxiliary brake in a vehicle

Technical Field of the Invention

The present invention relates to a method for showing a driver of a vehicle that at least one

auxiliary brake is activated and warning the driver when the at least one auxiliary brake is not able to produce a predetermined braking effect/torque.

Heavy commercial vehicles are today in addition to wheel brakes normally equipped with auxiliary brakes, such as an exhaust brake and a fluid brake, hereinafter called a retarder. The auxiliary brakes dramatically decreases wear on disc- and drum brakes and may be activated manually through a lever in a cab of the vehicle and also automatically through an electronic brake system distributing a requested braking action among the different brakes.

The retarder typically comprises a stator and a rotor driven by an output shaft of a gearbox or an engine in the vehicle. A fluid medium, such as hydraulic oil may be inserted into the retarder, and the retarder brakes by letting the oil brake a rotor shaft. Kinetic energy of the vehicle is thereby converted into heat, which must be transferred from the retarder oil in order

for the retarder to be able to brake without a reduced braking torque. If a retarder control unit determines that e.g. the temperature of the oil or a coolant in a cooling system for the retarder is too high, the oil supply to the retarder is reduced. Thereby the braking torque of the retarder is reduced.

The company Allison Transmission provides a warning system for a driver of the vehicle. The warning system comprises two warning lights. When the retarder is activated one of the warning lights is turned on in order to give the driver a sign that the retarder is activated and provides a braking torque according to a brake request. But if the retarder is forced to reduce its braking torque the second warning light is turned on in order to warn the driver that a

reduced braking torque is supplied from the retarder. Hence the driver is made observant of the reduced braking torque.

Summary of the invention

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The object of the present invention is to provide an auxiliary brake warning system for the same purpose as the warning system described above, but which is cheaper to manufacture and install, more space saving and draws the attention of the driver in a better way than the above mentioned warning system.

The invention relates to a method for showing a driver of a vehicle that at least one auxiliary brake is activated and warning the driver when the at least one auxiliary brake is not able to produce a predetermined braking effect/torque. The method comprises the steps of:

determining a braking torque provided by the at least one auxiliary brake,

determining if a maximum allowed braking torque has to be reduced in order to avoid damage on the vehicle,

activating a first kind of light in an indicator visible to the driver of the vehicle...