Patent ID: 12202379

DETAILED DESCRIPTION

FIG.1shows a combination10on a roadway11. The combination10includes a towing vehicle12and a trailer vehicle14with a braking system15. A brake pedal16is arranged in the towing vehicle12, via which brake pedal a braking request20can be generated by a driver. The braking request20is sent to a brake control unit (EBS)18of the towing vehicle12. The braking request20is then forwarded unchanged or adapted from the brake control unit18to a trailer brake control unit (TEBS)22. The trailer brake control unit22has an anti-lock braking system23in order to reduce the period of time during which the wheels30of the trailer vehicle14lock in the event of heavy braking.

Accordingly, the braking request20is converted by the brake control unit18of the towing vehicle12into a brake pressure34for actuating friction brakes, not shown, of the towing vehicle12and, depending on the type of braking request20, the braking request20itself or a braking request20which is generated by the brake control unit18of the towing vehicle12for the trailer brake control unit22is transmitted to the trailer brake control unit22of the trailer vehicle14. The trailer brake control unit22controls an electric drive24depending on the braking request20, in that the braking request20is also transmitted to a control unit26of the electric drive24. In a further embodiment not shown here, but which is also covered by the disclosure, the control unit26of the electric drive24is a component of the trailer brake control unit22. Depending on the braking request20, friction brakes28are also actuated, which are arranged on each wheel30of the axles32of the trailer vehicle14. This is done by forwarding a brake pressure34to actuate the friction brakes28.

In order to generate a suitable braking force in the form of the brake pressure34by the trailer brake control unit22depending on the braking request20, a control unit37of an air suspension system, shown here as an electronic air suspension system (ECAS)38, supplies the trailer brake control unit22with data corresponding to partial masses42a,42b,42cwhich act on the individual axles32or the individual wheels30of the trailer vehicle14. According to an alternative embodiment of the disclosure, not shown in the figures, all the features ofFIG.1are included, although, in deviation fromFIG.1, the air suspension system38is integrated into the trailer brake control unit22. Thus, alternatively, the brake pressure34is also measured directly in the trailer brake control unit22and the partial masses42a,42b,42care determined accordingly in the trailer brake control unit22without an independent control unit37of the air suspension system38.

In the trailer brake control unit22, a total mass of the trailer vehicle14can be determined from these partial masses42a,42b,42c. The partial masses42a,42b,42care determined in the control unit37of the electronic air suspension system38by measuring pressure values of air bellows40arranged on each of the wheels30and deriving the partial masses42a,42b,42cof the trailer vehicle14from this. According to an alternative embodiment not shown in the figures, substantially all the features ofFIG.1are included, with the exception that, in contrast toFIG.1, only one sensor is provided in one of the air bellows for measuring a total mass.

In addition to the control unit26for the electric drive24, the electric drive24has an inverter44which, depending on the control with the control unit26, supplies an electric motor46, which is here a central axle motor, with energy from a battery48in order to drive the wheels30of the axle32, which are connected to the electric motor46. For braking, the inverter44is controlled so that electrical energy flows into the battery48in a regenerative operation of the electric motor46. According to this embodiment, the control unit26of the electric drive receives actuation signals from the trailer brake control unit22in order to operate the electric drive24. Information49from the trailer brake control unit22is fed to the control unit26of the electric drive24to control the inverter44. The control unit26of the electric drive24or the trailer brake control unit22also determine a wheel speed of the wheels30of the electrically driven axle32depending on the speed of the electric motor46or depending on wheel speed sensors50, which are shown here only on the non-driven wheels30. From this, a slip can be determined with the control unit26or the trailer brake control unit22, so that locking wheels can be detected. In addition, the trailer brake control unit22can be used to determine a deceleration torque54in order to operate the electric drive24during the braking and/or pressure-holding phases in regenerative mode, also known as recuperation mode, during braking performed by the anti-lock braking system23.

FIG.2shows steps of an embodiment of the method68. In a step70, a first mass69of a driven axle32and a second mass71of a non-driven axle32of the trailer vehicle14are determined by the trailer brake control unit22, for example retrieved from a memory. Based on the first mass69and the second mass71, a differential mass72is determined in step74. The differential mass72corresponds to the mass which acts more on the wheels30of the central axle32shown inFIG.1than on the wheels30of the other axles32due to the weight of the electric drive24, in particular the electric motor46. In step75, further values, such as the acceleration due to gravity76and the dynamic tire radius78as well as an inclination80exhibited by the trailer vehicle, are retrieved in order to also determine the deceleration torque54in this step75.

If locking of one of the wheels30is now detected in step84during a braking request20, ABS braking is triggered in step86. For this purpose, the pressures34at the friction brakes28are reduced in step88. In step90, as soon as the wheels30start up again, the electric drive24is used to generate braking with the deceleration torque54. At the same time, the friction brakes28are activated in step92. As soon as a new locking of the wheels30is detected in step94, a propulsion torque97is generated with the electric drive24in step96and the friction brakes28are simultaneously released again in step98. Step90then follows again and the subsequent steps are repeated until the braking request20has been canceled by the driver or the towing vehicle and trailer combination10has come to a standstill.

It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

List of Reference Signs [Part of the Description]

10combination11roadway12towing vehicle14trailer vehicle15braking system16brake pedal18brake control unit (EBS)20braking request22trailer brake control unit (TEBS)23anti-lock braking system24electric drive26control unit28friction brakes30wheels32axles34brake pressure37control unit38electronic air suspension system (ECAS)40air bellows42apartial mass42bpartial mass42cpartial mass44inverter46electric motor48battery49information50wheel speed sensor54deceleration torque68method69first mass70receipt of partial masses71second mass72differential mass74determination of differential mass75retrieval of further values and determination of deceleration torque76acceleration due to gravity78dynamic tire radius80inclination of the trailer vehicle84detection of wheel locking86triggering of ABS braking88reduction of friction brake pressures89bleeding phase90generation of braking92activation of friction brakes93braking and/or pressure-holding phase94further detection of wheel locking96generation of propulsion torque97propulsion torque98release of friction brakes