Drive unit for a hybrid vehicle and method for operating the same

Patent metadata

Field	Value
Publication number	US-9738149-B2
Application number	US-201314443211-A
Country	US
Kind code	B2
Filing date	Oct 10, 2013
Priority date	Nov 15, 2012
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A drive unit for a hybrid vehicle includes a drive assembly with an internal combustion engine and an electric motor, and a transmission featuring several sub-transmissions shifting between the drive assembly and an output. Through a planetary transmission, the electric motor is coupled to an input shaft of a first sub-transmission and an input shaft of a second sub-transmission. Through a separating clutch, the internal combustion engine is to the input shaft of the first sub-transmission and, if the separating clutch is locked, is coupled to the same element of the planetary transmission as the input shaft of the first sub-transmission. A bypass shift element works with the planetary transmission such that, with a locked bypass shift element, a torque-proof connection between the electric motor, the input shaft of the first sub-transmission and the input shaft of the second sub-transmission exist, while, with an open bypass shift element, this torque-proof connection between the electric motor and the two input shafts of the two sub-transmissions does not exist. The separating clutch is formed as a frictional-locking or positive-locking separating clutch, and the bypass shift element is formed as a frictional-locking bypass shift element.

First claim

The invention claimed is:

1. A drive unit for a hybrid vehicle, comprising:
a drive assembly with an internal combustion engine, an electric motor, and a transmission with at least a first sub-transmission parallel to a second sub-transmission between the drive assembly and an output;
the electric motor coupled to an input shaft of the first sub-transmission and an input shaft of the second sub-transmission through a planetary transmission;
the internal combustion engine able to couple to the input shaft of the first sub-transmission through a clutch and, when the clutch is locked, is coupled to a same element of the planetary transmission as the input shaft of the first sub-transmission;
a bypass shift element configured in such a manner that: (a) when the bypass shift element is locked, a torque-proof connection between the electric motor, the input shaft of the first sub-transmission and the input shaft of the second sub-transmission exists, and (b) with the bypass shift element open, the torque-proof connection between the electric motor and the two input shafts of the two sub-transmission does not exist;
wherein the clutch is a frictional-locking or positive-locking separating clutch, and the bypass shift element is a frictional-locking bypass shift element; and
the frictional-locking bypass shift element is interactively configured with the transmission as a power-shifting element for execution of a power shift in an all-electric driving mode, wherein:
upon execution of a drive upshift and upon execution of a coast downshift, the power-shifting element is switched on or locked; and
upon the execution of a drive downshift and upon the execution of a coast upshift, the power-shifting element is switched off or opened.

2. A method for operating the drive unit for a hybrid vehicle, wherein the drive unit comprises:
a drive assembly with an internal combustion engine, an electric motor, and a transmission with at least a first sub-transmission parallel to a second sub-transmission between the drive assembly and an output;
the electric motor coupled to an input shaft of the first sub-transmission and an input shaft of the second sub-transmission through a planetary transmission;
the internal combustion engine able to couple to the input shaft of the first sub-transmission through a clutch and, when the clutch is locked, is coupled to a same element of the planetary transmission as the input shaft of the first sub-transmission;
a bypass shift element configured with the planetary transmission in such a manner that: (a) when the bypass shift element is locked, a torque-proof connection between the electric motor, the input shaft of the first sub-transmission and the input shaft of the second sub-transmission exists, and (b) with the bypass shift element open, the torque-proof connection between the electric motor and the two input shafts of the two sub-transmission does not exist;
the method comprising:
using the frictional-locking bypass shift element as a power-shifting element for execution of a power shift in all-electric driving mode, wherein,
upon the execution of a drive upshift and upon the execution of a coast downshift, the power-shifting element is closed; and
upon the execution of a drive downshift and upon the execution of a coast upshift, the power-shifting element is opened.

3. The method according to claim 2 , wherein for the execution of a drive upshift or a coast downshift in all-electric driving mode, when the frictional-locking bypass shift element and the separating clutch are both open and one gear is engaged in both sub-transmissions:
initially, bringing the frictional-locking bypass shift element into engagement to unload the first sub-transmission;
subsequently, the engaged gear in the first sub-transmission is disengaged;
thereupon, the frictional-locking bypass shift element is synchronized; and
subsequently, the frictional-locking bypass shift element is locked.

4. The method according to claim 2 , wherein for the execution of a drive downshift or a coast upshift in all-electric driving mode, when the frictional-locking bypass shift element is locked, the separating clutch is open, one gear is engaged in the second sub-transmission, and the first sub-transmission is in neutral:
initially, reducing a torque-transfer capacity of the frictional-locking bypass shift element by bringing the frictional-locking bypass shift element into slip;
whereas, through adjustment of rotational speed of the electric motor, the first sub-transmission is synchronized to a target gear of the power shift to be executed;
thereupon, the target gear is engaged in the first sub-transmission; and
subsequently, the frictional-locking bypass shift element is opened.

5. The method according to claim 2 , wherein for coupling of the internal combustion engine to the transmission through the positive-locking separating clutch with assistance of the frictional-locking bypass shift element:
synchronizing rotational speed of the input shaft of the first sub-transmission to rotational speed of the internal combustion engine while maintaining pulling force at the output.

6. The method according to claim 5 , wherein for coupling of the internal combustion engine in all-electric driving mode when the frictional-locking bypass shift element is locked, the separating clutch is open, one gear is engaged in the second sub-transmission, and the first sub-transmission is in neutral:
initially, reducing torque-transfer capacity of the frictional-locking bypass shift element by bringing the frictional-locking bypass element into slip;
whereas, through an adjustment of rotational speed of the electric motor, the positive-locking separating clutch is synchronized;
thereupon, the positive-locking separating clutch is locked;
subsequently, through a load transfer to the internal combustion engine, the frictional-locking bypass shift element is unloaded;
thereupon, the first sub-transmission is synchronized to a suitable gear and this gear is engaged in the first sub-transmission; and
subsequently, through a further load transfer to the internal combustion engine, the electric motor is unloaded.

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Kaltenbach Johannes
• Griesmeier Uwe

Classifications

• Y10S903/91

  Orbital, e.g. planetary gears · CPC title

• B60W2710/1011

  Input shaft speed, e.g. turbine speed · CPC title

• F16H3/006

  power being selectively transmitted by parallel flow paths, e.g. dual clutch transmissions · CPC title

• B60W20/40

  Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers {(power-up or power-down of the driveline B60W30/192)} · CPC title

• F16H2200/0056

  the gear ratios comprising seven forward speeds · CPC title