Method for operating a drive train of a working machine, electrified drive train, and working machine

Abstract

A method for operating a drive train of a working machine, the drivetrain having a drive motor, a service brake, and an assisting brake, wherein a drive coupling is between the drive motor of the drive train and at least one wheel of the working machine such that a braking torque of the drive motor counteracts a downhill slope force acting on the working machine. Automated actuation of the assisting brake is undertaken if the working machine is subject to an impermissible acceleration, where the assisting brake is actuated in accordance with a required braking torque and in accordance with a thermal loading of the assisting brake. The assisting brake is configured as a spring-pressurized and hydraulically or pneumatically releasable brake. An electrified drive train and a corresponding working machine are also disclosed.

1 - 13 . (canceled) 
     
     
         14 . A method for operating a drive train of a working machine, comprising:
 providing the working machine having a drive motor, a service brake, an assisting brake, and a drive coupling of the drive motor of the drive train with at least one wheel of the working machine, wherein the assisting brake is configured as a spring-applied and hydraulically or pneumatically releasable brake;   operating the drive train on a downhill slope;   counteracting, by a braking torque of the drive motor, a downhill slope force acting on the working machine;   detecting an impermissible acceleration; and   automatically actuating the assisting brake in response to detecting the impermissible acceleration, wherein actuating the assisting brake is performed in accordance with a predefined braking torque and in accordance with a thermal load on the assisting brake.   
     
     
         15 . The method of  claim 14 , wherein the drive motor is configured as an electric motor and provides the braking torque generated by the drive motor in a recuperation mode. 
     
     
         16 . The method of  claim 14 , comprising:
 determining a quantity of heat supplied to the assisting brake in a braking operation; and   increasing an accumulating counter during actuation of the assisting brake.   
     
     
         17 . The method of  claim 16 , comprising:
 reducing the accumulating counter over time during a period of no actuation of the assisting brake.   
     
     
         18 . The method of  claim 17 , wherein reducing the accumulating counter is performed only during movement of the working machine. 
     
     
         19 . The method of  claim 17 , comprising:
 continuously detecting a current travel speed of the working machine;   continuously comparing the current travel speed with a predefined limit speed;   determining that the predefined limit speed is exceeded; and   adjusting the braking torque of the assisting brake by modulating the hydraulic or pneumatic pressure in such a way that the actuation of the assisting brake reduces a travel speed of the working machine to such an extent that impermissible acceleration no longer occurs ( 106 ) solely due to the braking torque generated by the drive motor.   
     
     
         20 . The method of  claim 16 ,
 determining that the accumulating counter is above a limit value; and   limiting a maximum permissible vehicle speed of the working machine. speed threshold value is reduced as long as the counter is above a limit value.   
     
     
         21 . The method of  claim 16 ,
 determining that the accumulating counter is above a limit value; and   reducing a speed threshold value while the counter is above the limit value.   
     
     
         22 . The method of  claim 19 ,
 determining that the predefined limit speed remains exceeded;   repeating actuation of the assisting brake a first time with a first changed modulation;   determining that the accumulation counter has reached the limit value; and   specifying a first changed limit value for the accumulation counter.   
     
     
         23 . The method of  claim 22 , further comprising:
 determining that the vehicle speed still remains above the predefined limit speed;   determining that the accumulation counter has reached the first modified limit value;   repeating the brake actuation a second time with a second modified modulation; and   specifying a second modified limit value for the accumulation counter.   
     
     
         24 . The method of  claim 16 , comprising:
 determining that the accumulation counter has reached a predefined limit value;   terminating actuation of the assisting brake;   
     
     
         25 . The method of  claim 16 , comprising:
 determining that the actuation of the assisting brake has reached a predefined time period; and   terminating actuation of the assisting brake.   
     
     
         26 . The method of  claim 16 , comprising:
 determining that the speed has fallen below the limit speed; and   terminating actuation of the assisting brake.   
     
     
         27 . The method of  claim 14 , comprising:
 terminating actuation of the assisting brake without the speed falling below the limit speed; and   emitting an acoustic and/or visual and/or haptic warning to a driver.   
     
     
         28 . An electrified drive train for a working machine, the drive train comprising:
 a drive motor;   a service brake;   an assisting brake; and   a drive coupling of the drive motor of the drive train with at least one wheel of the working machine, so that a braking torque of the drive motor is configured to counteract a downhill slope force acting on the working machine;   wherein the drive train is configured to automatically actuate the assisting brake if the working machine is subject to an impermissible acceleration; and   wherein the drive train is configured to actuate the assisting brake in accordance with a required braking torque and in accordance with a thermal load on the assisting brake; and   wherein the assisting brake is configured as a spring-applied and hydraulically or pneumatically releasable brake.   
     
     
         29 . The drive train of  claim 28 , wherein the drive train is configured to carry out the method of  claim 14 . 
     
     
         30 . A working machine comprising the drive train of  claim 28 .