Patent ID: 8718882

Claim:
A method of controlling a transmission brake in an automated variable-speed transmission of countershaft design and comprising claw clutches, the transmission brake being functionally connected to a transmission shaft ( 2 ) on an input side and being either hydraulically or pneumatically actuated by an inlet valve ( 13 ) and an outlet valve ( 15 ), each of the inlet valve ( 13 ) and the outlet valve ( 15 ) being a 2/2-way magnetic switching valve such that, for an upshift from a gear under load to a target gear, once a loaded gear is disengaged, for synchronizing the target gear, the inlet valve ( 13 ) being first opened and the outlet valve ( 15 ) being closed, and after a braking torque (M Br0 ) is applied, the inlet valve ( 13 ) is closed, and during the braking of the input-side transmission shaft ( 2 ), a time interval until the emission of a disengagement signal (T SA ), for opening the outlet valve ( 15 ), is determined as a function of an input speed (n E ) and a gradient (Δn E /Δt) of the input speed and an output speed (n A ) and a gradient (Δn A /Δt) of the output speed, in such manner that when the transmission brake ( 1 ) is disengaged, the input speed (n E ) corresponds to a specified synchronous speed (n E ≈n A ), the method comprising the steps of: determining, with sensors, a current actual input speed (n E — akt ) and a current actual output speed (n A — akt ) and calculating the gradients of the input speed (Δn E /Δt) and the output speed (Δn A /Δt) from the current actual input speed (n E — akt ) and the current actual output speed (n A — akt ); determining a speed variation of the input speed (n E (t)), during an imminent disengagement process of the transmission brake ( 1 ), by a quadratic time function as a function of the gradient of the input speed (Δn E /Δt); determining an optimum time (t Sync ) for reaching a synchronous speed (n Sync ), during the disengagement process of the transmission brake ( 1 ), from a speed variation of the input speed (n E (t)) as a function of the gradient of the output speed (Δn A /Δt); determining the time interval (T SA ) until emission of the disengagement signal as a function of the current actual input speed (n E — akt ) and the gradient (Δn E /Δt) of the current actual input speed and the current actual output speed (n A — akt ) and the gradient (Δn A /Δt) of the current actual output speed, by a back-calculation from the time (t Sync ) when the synchronous speed (n Sync ) is reached, taking a disengagement dead time (T TA ) of the transmission brake ( 1 ), between the emission of the disengagement signal (t SA ) and the beginning of the disengagement process (t Abs0 ), into account.