| 摘要 |
A method of controlling a transmission brake of an automated change-speed transmission, of a countershaft design provided with claw clutches, the brake being functionally connected, on its input side, to a transmission shaft and actuated hydraulically or pneumatically by way of inlet and outlet valves such that, for an upshift from a gear under load to a target gear, when the loaded gear is disengaged, in order to synchronize the target gear, first the inlet valve is opened and the outlet valve is closed, then to produce a substantially constant braking torque, the inlet valve is closed after having been open for a determinable opening duration, and to reach a synchronous rotational speed, the outlet valve is opened after having been closed for a determinable closing duration. The time during which the inlet valve is open is determined as a function of a specified characteristic parameter of the synchronization process. |
| 主权项 |
1. A method of controlling a transmission brake of an automated change-speed transmission, of a countershaft design provided with claw clutches, the transmission brake is functionally connected, on an input side thereof to a transmission shaft and is actuated either hydraulically or pneumatically by an inlet valve and an outlet valve, each of the inlet and the outlet valves is a 2/2-way magnetic switching valve, such that, for an upshift from a gear under load to a target gear, when the loaded gear has been disengaged, to synchronize the target gear, first the inlet valve is opened and the outlet valve is closed, then to produce a substantially constant braking torque (MBr) the inlet valve is closed after having been open for a determinable opening time duration (TVE), and to reach a synchronous rotational speed, the outlet valve is opened after having been closed for a determinable closing time duration (TVA), the opening time duration (TVE) for which the inlet valve is open being determined as a function of a specified characteristic parameter of the synchronization process, the method comprising the steps of:
detecting, with sensors, an initial input rotational speed (nE—0) and a corresponding initial output rotational speed (nA—0) existing at a beginning of the synchronization process (t=t0); determining, with a transmission control unit and from the initial input and the initial output rotational speeds, an input speed gradient (ngE—W) and a corresponding output speed gradient (ngA) existing before activation of the transmission brake; determining, with the transmission control unit, a necessary braking gradient (ngE—Br) of the input shaft from values of the determined input and the output speed gradients existing before activation of the transmission brake and from transmission-specific and brake-specific characteristic values, for a specified application duration (TH) of the transmission brake at a constant braking torque (MBr=const.); determining, with the transmission control unit, a needed brake pressure (pBr) to be produced in the transmission brake for obtaining the necessary braking gradient (ngE—Br); determining, with the transmission control unit, the opening time duration (TVE) of the inlet valve required in order to produce the needed brake pressure (pBr) as a function of a current brake pressure (pV) that is currently being supplied to the transmission brake; and calculating the necessary braking gradient (ngE—Br) from a synchronization duration (TS), the input and the output rotational speeds (nE—0, nA—0) and the input and the output speed gradients (ngE—W, ngA) at the beginning of the synchronization process (t=t0) using the equation:
ngE—Br=FAbs*TH−ngE—W+2ngA+{(FAbs*TH−ngE—W+2ngA)2+2FAbs[nE—0−nA—0+(T1+TH)(ngE—W −2 ngA)]}1/2 where ng E—Br is the necessary braking gradient,
FAbs is a transmission-specific and brake-specific deactivation factor of the transmission brake,TH is the specified application duration,ngE—W is the input speed gradient,ngA is the output speed gradient,nE—0 is the input rotational speed, nA—0 is the output rotational speed, andT1 is a device-specific activation lag time of the transmission brake. |
