Interrelated power delivery controls – including engine control – Transmission control – With clutch control
Patent
1999-07-08
2000-06-27
Ta, Khoi Q.
Interrelated power delivery controls, including engine control
Transmission control
With clutch control
477 80, 74 1586, 180 531, B60K 1728
Patent
active
06080081&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a control of power take-offs in transmissions having available an automated or partially automated shifting device.
BACKGROUND OF THE INVENTION
In modern commercial vehicles shifting devices are being offered for partial automatic shifting of multi-step, especially multi-step change speed gears of motor vehicles having a clutch situated between the prime mover and the transmission and an electronic control unit for determining admissible shifting recommendations.
For the driver's assistance and to improve the economy when driving with commercial vehicles, especially those equipped with multi-ratio transmissions, several partially automatic shifting devices have been proposed and also developed for dealing with different problems and strategies.
Multi-step transmissions of that kind have as a rule a plurality of power take-off possibilities. Said power take-offs are not only synchronized but claw-clutch engaged. To engage the power take-off, there must be no great difference in the number of revolutions of the claw, since otherwise an undesirable grating noise appears. On the other hand, in case of a difference in the number of revolutions of almost zero, there is great probability of a tooth-on-tooth position of the claws resulting in the power take-off being unable to mesh.
SUMMARY OF THE INVENTION
The problem on which the invention is based is to develop further an automated or partially automated transmission having an automated clutch so as to obtain a reliable engagement of the claws.
In order to make possible in an automated transmission of a commercial vehicle the engagement of a power take-off, it is proposed according to the invention that the driver delivers his wish to switch on the power take-off in the form of a signal, for example, via a switch or push-button. The signal is converted in a control device to a signal for opening an automatic separating clutch between the prime mover and the transmission of the commercial vehicle. The number of revolutions of the input shaft is monitored by means of sensors. After reaching a predetermined minimum number of revolutions of the input shaft of the transmission, a shifting device is controlled for connecting the power take-off with a transmission shaft in order to close said shifting device. In the transmission this is the transmission shaft which is provided for driving the power take-off. Depending on the type of transmission these can be different transmission shafts. Here it is preferably a countershaft provided parallel to a main shaft disposed coaxially relative to the input shaft of the transmission. In a transmission having two countershafts disposed in parallel, to one of the two countershafts the power take-off is preferably attached for distribution of load to said two countershafts. The clutch is then closed again. Hereby a torsional torque is again applied to the driving transmission shaft whereby the teeth of the opposite structural parts of the shifting device can revolve relative to each other to avoid or eliminate the possibility of the teeth remaining in front of each other.
Another advantageous development has sensors which ensure that the power take-off will be switched on only when the conditions have been fulfilled that the prime mover of the vehicle works, that the vehicle is stopped, that the transmission is in a neutral position and that no shifting of the transmission is active or has been initiated.
In another advantageous development reaching the minimum number of revolutions is accelerated by a braking device in the transmission. It is possible, for example, to place on the countershafts or one of the countershafts an inertia brake in the form of a multi-disc brake. Braking devices are also possible on the input shaft.
One other advantageous development has one sensor on the shifting device with which it is determined whether a difference in the number of revolutions exists between the transmission's shaft and the shaft connected with the power take-off or whether a d
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Hensinger Klaus
Sauermann Gerd
Ta Khoi Q.
ZF Friedrichshafen AG
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