Interrelated power delivery controls – including engine control – Transmission control – With clutch control
Reexamination Certificate
2002-07-18
2004-12-28
Estremsky, Sherry (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
With clutch control
C477S084000
Reexamination Certificate
active
06835161
ABSTRACT:
This application claims the priority of German Patent Document No. DE 101 35 327.8, filed Jul. 19, 2001, the disclosure of which is expressly incorporated by reference herein.
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to methods for changing gear in an automated change-speed gearbox of a motor vehicle and to an automated change-speed gearbox.
EP 0 695 665 B1 describes a control system for a gearbox with a servo device, which is assigned to an engine of a motor vehicle. The control system has an actuating device, which can be actuated to select and disengage a gear, perform a gear selection, and engage and disengage a clutch. The engine has a first processing unit, which regulates the torque provided by the engine and the rotational speed of engine.
A second processing unit of the control system is suitable, in the case of a gear change from an original gear to a target gear, in particular during a downshift, for supplying control information to the first processing unit of the engine before the disengagement of the original gear to bring about a controlled reduction of the torque provided by the engine. Before the target gear is selected, the first processing unit supplies the second processing unit with further control information in order to bring a rotational speed of the engine to a given target value. During this process, the clutch is either closed for the entire time or it is opened before the original gear is disengaged and is completely closed after the original gear is disengaged.
DE 198 59 458 A1 discloses a gearbox in the form of a change-speed gearbox. The gearbox has a shiftable drive-away clutch arranged on the input side and additional clutches, in particular power-shift clutches, which engage gearwheels with a shaft. It also describes a method for changing from an original gear to a target gear, in particular for downshifting. The gear change is carried out without control of engine torque. After the start of shifting, a power-shift clutch is closed. When the power-shift clutch is transmitting the full torque, the original gear can be deselected. A gearbox input shaft is then brought to a higher target rotational speed. As soon as the target rotational speed has been reached, the target gear is selected. The drive-away clutch remains closed during the entire shift operation or is opened during the deselection of the original gear and the selection of the target gear.
In view of the prior art, it is an object of the present invention to provide an automated change-speed gearbox and methods for changing gear in such a gearbox, to provide smooth operation of the automated change-speed gearbox and particularly short shifting times for downshifts.
This object is achieved by the embodiments of the present invention described hereinafter.
In the case of a method according to the invention for shifting down from an original gear to a target gear, an automated clutch arranged between the engine and the change-speed gearbox is engaged up to, at most, a slip limit to increase the rotational speed of an input shaft of the change-speed gearbox.
During a downshift, the input shaft of the change-speed gearbox must be brought to a synchronization speed of the target gear, which is greater than the rotational speed of the input shaft in the original gear. The synchronization speed is achieved when a selector element of the target gear and a gearwheel of the target gear are at the same rotational speed. The input shaft is accelerated by a torque provided by the driving engine. For this purpose, the clutch arranged between the driving engine and the change-speed gearbox must transmit a torque. The clutch is engaged up to, at most, the slip limit by an actuator. The slip limit is reached when the clutch cannot transmit more than the torque applied and would thus slip if there were a very slight increase in the torque. It is particularly advantageous if the clutch is operated precisely at the slip limit. In this case, the rotational speed of the driving engine and that of the input shaft of the change-speed gearbox are identical.
This allows particularly smooth operation of the change-speed gearbox since torque peaks of the engine which occur are not transmitted to the change-speed gearbox. Moreover, torque surges, which are introduced from the road via driven wheels, are not taken by the driving engine but lead to slipping of the clutch.
In the method according to the invention for shifting down in an automated change-speed gearbox with just one automated clutch arranged between the engine and the change-speed gearbox, the clutch is at least partially disengaged to deselect the original gear. The change-speed gearbox does not have any other clutches, in particular power-shift clutches. To deselect the original gear and hence release a selector element of the original gear from a gearwheel of the original gear, only a very low torque must be transmitted from the selector element to the gearwheel or vice versa. The clutch can, for example, be opened only until the absolute value of the torque at the selector element of the original gear has undershot a threshold value. The torque at the selector element can be calculated by a control device that carries out the method according to the invention. Calculation can, for example, take place on the basis of the torque provided by the engine, the rotational speeds and the rotational-speed time derivative of the individual shafts in the change-speed gearbox and physical parameters, e.g. the mass moment of inertia, of individual components or subassemblies of the change-speed gearbox. The clutch can be disengaged by a ramp or by a predetermined characteristic or abruptly, for example.
The rotational speed of the engine is adjusted in the direction of the synchronization speed of the target gear simultaneously with the opening of the clutch. Adjustment can be accomplished by control and/or regulation of the rotational speed and/or of the torque provided by the engine. After the deselection of the original gear, the clutch is at least partially reengaged in order to match the rotational speed of the input shaft of the change-speed gearbox to the rotational speed of the engine and hence increase it.
This leads to particularly short shifting times for a downshift since the input shaft of the change-speed gearbox reaches the synchronization speed of the target gear particularly quickly, and the target gear can thus be selected particularly quickly. Any interruption in the tractive effort at the vehicle wheels during the shift is thus particularly short.
In addition, a considerable reduction in the cost of the change-speed gearbox is achieved by the elimination of power-shift clutches.
In another method according to the invention, the clutch is disengaged to deselect the original gear, ensuring torque can no longer be transmitted by the clutch. For the deselection of the original gear and hence for the release of a sector element of the original gear from a gearwheel of the original gear, only a very low torque must be transmitted from the selector element to the gearwheel or vice versa. If this is achieved by disengaging the clutch, the original gear can be deselected without the possibility that torque surges will be introduced into the motor vehicle. This allows smooth operation of the motor vehicle.
In yet another method according to the invention, the clutch is partially disengaged to deselect the original gear. The clutch is disengaged only until a selector element of the original gear can be disengaged.
In still yet another method according to the invention, the rotational speed of the engine is adjusted in the direction of the synchronization speed of the target gear simultaneously with the disengagement of the clutch. This allows particularly short shifting times since the engine and, after the partial engagement of the clutch, the input shaft of the change-speed gearbox, reach the synchronization speed in as short a time as possible. The target gear can thus be selected after a particularly short time.
In a further
Grillenberger Martin
Heinzel Markus
Salecker Michael
Tinschert Friedo
Wieland Dittmar
Crowell & Moring LLP
Daimler-Chrysler AG
Estremsky Sherry
LandOfFree
Automated change-speed gearbox and methods for changing gear... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automated change-speed gearbox and methods for changing gear..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automated change-speed gearbox and methods for changing gear... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3333389