Shift control method for an automated range-change transmission

Patent metadata

Field	Value
Publication number	US-10508724-B2
Application number	US-201715813753-A
Country	US
Kind code	B2
Filing date	Nov 15, 2017
Priority date	Nov 22, 2016
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

A method for shift control of an automated auxiliary transmission that is mounted in a drive train of a motor vehicle between a drive motor (AM) and a final drive, and includes at least one multi-step main gearing (HG) and one two-step front-mounted group (VG) connected upstream of the main gearing (HG), and with which the main gearing (HG) can be shifted via unsynchronized clutches and the front-mounted group can be shifted via synchronized clutches. Depending on the currently existing driving or operating situation, a gear change is performed in the auxiliary transmission through a change in the transmission ratio step (G 1 , G 2 , G 3 ) of the main gearing (HG) while maintaining the currently engaged transmission ratio step (K 1 , K 2 ) in the front-mounted group (VG).

First claim

The invention claimed is:

1. A method for shift control of an automated auxiliary transmission, which is mounted in a drive train of a motor vehicle between a drive motor and a final drive and comprises at least one multi-step main gearing and one two-step front-mounted group upstream of the main gearing, and in which the main gearing is shiftable via unsynchronized clutches and the front-mounted group is shiftable via synchronized clutches, the method comprising:
determining either a current transmission fluid temperature or a current ambient temperature;
comparing the determined current transmission fluid temperature or the current ambient temperature to a defined threshold;
if the determined current transmission fluid temperature or the determined current ambient temperature is lower than the defined threshold, changing a gear in the auxiliary transmission by changing a transmission ratio step of the main gearing while maintaining a currently engaged transmission ratio step in the front-mounted group;
if the determined current transmission fluid temperature or the determined current ambient temperature is higher than the defined threshold, determining a current driving resistance of the motor vehicle;
comparing the current driving resistance to first and second set thresholds; and
if the current driving resistance does not fall below the first set threshold and does not exceed the second set threshold, performing a gear change of the auxiliary transmission by changing the transmission ratio step of the main gearing while maintaining the currently engaged transmission ratio step in the front-mounted group.

2. The method according to claim 1 , wherein the auxiliary transmission has a two-step range group connected downstream of the main gearing, and the method further comprising, depending on an assessment of a currently existing driving or operating situation, changing the gear in the auxiliary transmission either by changing the transmission ratio step of the main gearing or by changing the transmission ratio step of the main gearing and changing a transmission ratio step of the range group while maintaining the currently engaged transmission ratio step engaged in the front-mounted group.

3. The method according to claim 1 , further comprising: determining a current vehicle speed;
comparing the current vehicle speed to a predetermined speed range; and
if the current vehicle speed lies within the predetermined speed range, performing the gear change of the auxiliary transmission by changing the transmission ratio step of the main gearing while maintaining the transmission ratio step engaged in the front-mounted group.

4. The method according to claim 1 , further comprising: determining a current driver input in a form of an accelerator pedal actuation;
comparing the current driver input to a further set threshold; and
if the current driver input exceeds the further set threshold, performing the gear change of the auxiliary transmission by changing the transmission ratio step of the main gearing while maintaining the transmission ratio step engaged in the front-mounted group.

5. The method according to claim 1 , further comprising: if the determined current transmission fluid temperature or the determined current ambient temperature is lower than the defined threshold, considering projection data for a decision of whether a gear change of the auxiliary transmission is to be performed while maintaining the transmission ratio step engaged in the front-mounted group, the projection data comprising route data of a driving route in front of the motor vehicle.

6. A control device for shift control of an auxiliary transmission of a motor vehicle, the control device comprising at least one receiving interface, which is configured to receive either a transmission temperature signal or an ambient temperature signal from a temperature sensor, and to receive input signals from drive train components, an evaluation unit, which is configured for determining a current transmission temperature or a current ambient temperature and comparing the current transmission temperature or the current ambient temperature to a defined threshold, and evaluating the received input signals or information of the received input signals, and a transmitter interface, for transmitting control signals to the drive train components, the control device being configured to activate shifting elements of individual groups of the auxiliary transmission to change a gear in the auxiliary transmission by changing a transmission ratio step of a multi-step main gearing while maintaining a currently engaged transmission ratio step in a two-step front-mounted group, if the current transmission fluid temperature signal or the current ambient temperature is lower than the defined threshold, and, the control device being configured to perform a gear change in the auxiliary transmission, while maintaining the currently engaged transmission ratio step in the two-step front-mounted group if the current transmission fluid temperature signal or the current ambient temperature is higher than the defined threshold and if a current driving resistance of the motor vehicle does not fall below a first set threshold and does not exceed a second set threshold.

7. The control device according to claim 6 , wherein the automated auxiliary transmission is mounted in a drive train of the motor vehicle between a drive motor and a final drive and comprises the main gearing and the two-step front-mounted group upstream of the main gearing, and in which the main gearing is shiftable, via unsynchronized clutches, and the two-step front-mounted group is shiftable, via synchronized clutches, and depending on a currently existing driving or operating situation, a gear in the auxiliary transmission is changed by changing a transmission ratio step of the main gearing while maintaining the currently engaged transmission ratio step in the two-step front-mounted group.

8. A computer program product, stored on a computer-readable data medium, for performing a method of shift control of an automated auxiliary transmission, which is mounted in a drive train of a motor vehicle between a drive motor and a final drive and comprises at least one multi-step main gearing and one two-step front-mounted group upstream of the main gearing, and in which the main gearing is shiftable, via unsynchronized clutches, and the front-mounted group is shiftable, via synchronized clutches, the method including, determining either a current transmission fluid temperature or a current ambient temperature, comparing the determined current transmission fluid temperature or the current ambient temperature to a defined threshold, and if the determined current transmission fluid temperature or the determined current ambient temperature is lower than the defined threshold, changing a gear in the auxiliary transmission by changing a transmission ratio step of the main gearing while maintaining a currently engaged transmission ratio step in the front-mounted group, and if the determined current transmission fluid temperature or the determined current ambient temperature is higher that the defined threshold, determining a current driving resistance of the motor vehicle, comparing the current driving resistance to first and second set thresholds; and if the current driving resistance does not fall below the first set threshold and does not exceed the second set threshold, performing a gear change of the auxiliary transmission by changing the transmission ratio step of the main gearing while maintaining the currently engaged transmission ratio step in the front-mounted group,
the computer program product being executed on a control device for the shift control of the auxiliary transmis

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Steinborn Mario
• Mayerhofer Tobias

Classifications

• F16H2306/48

  Synchronising of new gear · CPC title

• F16H63/44

  Signals to the control unit of auxiliary gearing · CPC title

• F16H2061/085

  Timing of auxiliary gear shifts · CPC title

• F16H61/70

  specially adapted for change-speed gearing in group arrangement, i.e. with separate change-speed gear trains arranged in series, e.g. range or overdrive-type gearing arrangements · CPC title

• F16H61/0403

  Synchronisation before shifting · CPC title