Hybrid drive of a motor vehicle and method for operating same

Patent metadata

Field	Value
Publication number	US-9731588-B2
Application number	US-201214364470-A
Country	US
Kind code	B2
Filing date	Nov 5, 2012
Priority date	Dec 21, 2011
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A hybrid drive of a motor vehicle has an internal combustion engine, an electric machine, and a transmission. The transmission is a multi-stage shifting transmission including two subtransmissions, each of which has a separate input shaft and a common output shaft. The first input shaft of a first subtransmission can be coupled to the internal combustion engine via a friction-locking clutch in such a way that when the clutch is engaged the internal combustion engine is coupled to the first input shaft and thus to the first subtransmission, and when the clutch is disengaged the internal combustion engine is decoupled from the first input shaft and thus decoupled from the first subtransmission. A second input shaft of a second subtransmission is rigidly coupled to the electric machine, and both input shafts can be coupled selectively to the common output shaft via form-locking shift elements of the subtransmissions.

First claim

The invention claimed is:

1. A hybrid drive of a motor vehicle comprising an internal combustion engine, an electric machine and a transmission, wherein the transmission is a multi-stage shifting transmission comprising:
a first subtransmission comprising a first input shaft; and
a second subtransmission comprising a second input shaft, said first and second subtransmissions sharing a common output shaft, said output shaft extending through said first and second subtransmissions, and said output shaft sharing a common axis with at least one of the first input shaft and the second input shaft,
wherein the first input shaft of the first subtransmission is coupled to the internal combustion engine via a friction-locking clutch in such a way that when the friction-locking clutch is engaged the internal combustion engine is coupled to the first input shaft and thus to the first subtransmission, and when the friction-locking clutch is disengaged the internal combustion engine is decoupled from the first input shaft and thus decoupled from the first subtransmission,
wherein the second input shaft of the second subtransmission is rigidly coupled to the electric machine and both the first and second input shafts are coupled selectively to the common output shaft via form-locking shift elements of the first and second subtransmissions, and
wherein the second input shaft of the second subtransmission is attached to first and second form-locking shift elements (A, B) in such a way that when the first form-locking shift element (A) is engaged the electric machine is coupled to the internal combustion engine and thus the internal combustion engine together with the electric machine is coupled to the second subtransmission, and when the second form-locking shift element (B) is engaged the electric machine is coupled to both the first and second input shafts of the first and second subtransmissions and thus the first subtransmission is coupled to the second subtransmission.

2. The hybrid drive according to claim 1 , wherein the first form-locking shift element (A) and the second form-locking shift element (B) are combined in one shifting group with a common actuator in such a way that only the first form-locking shift element is engaged or only the second form-locking (B) is engaged or both shift elements (A, B) are disengaged.

3. The hybrid drive according to claim 1 , wherein the first and second input shafts are disposed coaxially to one another.

4. A method for operating a hybrid drive for a motor vehicle, the hybrid drive having an internal combustion engine, an electric machine, and a multi-stage shifting transmission with a first subtransmission having a first input shaft and a second subtransmission having a second input shaft, the second input shaft and the first input shaft sharing a common output shaft that is concentric with the first input shaft and the second input shaft, the method comprising:
engaging a first form-locking shift element (A) when the electric machine is in a generator mode and when a speed of the motor vehicle is lower than a limit value; and
disengaging the first form-locking shift element (A) when the speed of the motor vehicle is higher than the limit value
wherein the first input shaft of the first subtransmission is coupled to the internal combustion engine via a friction-locking clutch in such a way that when the friction-locking clutch is engaged the internal combustion engine is coupled to the first input shaft and thus to the first subtransmission, and when the friction-locking clutch is disengaged the internal combustion engine is decoupled from the first input shaft and thus decoupled from the first subtransmission,
wherein the second input shaft of the second subtransmission is rigidly coupled to the electric machine and both the first and second input shafts are coupled selectively to the common output shaft via form-locking shift elements of the first and second subtransmissions, and
wherein the second input shaft of the second subtransmission is attached to first and second form-locking shift elements (A, B) in such a way that when the first form-locking shift element (A) is engaged the electric machine is coupled to the internal combustion engine and thus the internal combustion engine together with the electric machine is coupled to the second subtransmission, and when the second form-locking shift element (B) is engaged the electric machine is coupled to both the first and second input shafts of the first and second subtransmissions and thus the first subtransmission is coupled to the second subtransmission.

5. The method of claim 4 , further comprising: when the motor vehicle is at a standstill in a generator mode of the electric machine, engaging the first form-locking shift element (A);
engaging a starting gear in the first subtransmission and engaging a neutral setting in the second subtransmission; and
engaging the friction-locking clutch maximally as far as a point of contact of the friction-locking clutch,
wherein for a subsequent start-up or creep drive, the friction-locking clutch is engaged beyond the point of contact, and the start-up or creep drive is terminated when the friction-locking clutch is adhering.

6. The method of claim 4 , further comprising:
starting with an internal combustion engine drive of the motor vehicle when friction-locking clutch is engaged and the first and second form-locking shift elements (A, B) are disengaged, in order to execute a gear change from a first gear of the first subtransmission to a target gear of the second subtransmission;
synchronizing first the target gear;
building up a load at the electric machine and decreasing a load at the internal combustion engine in order to provide a load transference from the internal combustion engine to the electric machine;
subsequently disengaging the first gear and synchronizing the second shift element (B); and
in order to provide a load transference from the electric machine back to the internal combustion engine, decreasing a load at the electric machine and building up a load at the internal combustion engine.

7. The method of claim 6 , further comprising disengaging the friction-locking clutch while the load transfers from the internal combustion engine to the electric machine.

8. The method of claim 6 , further comprising engaging the friction-locking clutch while the load transfers from the electric machine to the internal combustion engine.

9. The method of claim 4 , wherein the friction-locking clutch is engaged, the first form-locking shift element (A) is disengaged and the second form-locking shift element (B) is engaged, the method further comprising:
for executing a gear change from a first gear of the second subtransmission to a target gear of the first subtransmission, first building up a load at the electric machine and decreasing a load at the internal combustion engine;
disengaging the second form-locking shift element (B) in order to provide a load transference from the internal combustion engine to the electric machine, thereafter the target gear being synchronized; and
subsequently, decreasing a load at the electric machine and building up a load at the internal combustion engine to ensure a load transference from the electric machine back to the internal combustion engine.

10. The method of claim 9 , further comprising disengaging the friction-locking clutch in order to provide the load transference from the internal combustion engine to the electric machine.

11. The method of claim 9 , further comprising engaging the friction-locking clutch to provide the load transference from the electric machine back to the internal combustion engine.

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Kaltenbach Johannes
• Griesmeier Uwe

Classifications

• B60W10/08

  including control of electric propulsion units, e.g. motors or generators · CPC title

• F16H3/097

  the input and output shafts being aligned on the same axis · CPC title

• B60K6/36 Primary

  characterised by the transmission gearings · CPC title

• B60K2006/4825

  Electric machine connected or connectable to gearbox input shaft · CPC title

• F16H2312/06

  Creeping · CPC title