Transmission control method

Patent metadata

Field	Value
Publication number	US-10173665-B2
Application number	US-201615147432-A
Country	US
Kind code	B2
Filing date	May 5, 2016
Priority date	May 6, 2015
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A method for operating a drive train of a motor vehicle is provided, the drive train featuring a first drive assembly formed as an internal combustion engine a second drive assembly formed as an electric motor, a start-up element and a transmission). The start-up element features a converter and a lock-up clutch and is connected between the electric motor and the transmission. The electric motor is connected between the internal combustion engine and the start-up element. If a decoupling of the lock-up clutch is requested, the lock-up clutch of the start-up element is initially brought into slip. If the slip at the lock-up clutch of the start-up element reaches a threshold or is greater than the threshold, a target rotational speed is subsequently predetermined for the electric motor and the rotational speed of the electric motor is adjusted to such target rotational speed.

First claim

The invention claimed is:

1. A method for operating a drive train of a motor vehicle, the drive train including an internal combustion engine, an electric motor, a start-up element and a transmission, the start-up element including a converter and a lock-up clutch, the start-up element connected between the electric motor and the transmission, the electric motor connected between the internal combustion engine and the start-up element, the method comprising:
bringing the lock-up clutch into slip when a decoupling of the lock-up clutch is requested;
determining a target rotational speed for the electric motor; and
adjusting a rotational speed of the electric motor to the target rotational speed in response to the slip at the lock-up clutch reaching a threshold or being greater than the threshold.

2. The method of claim 1 , wherein a first target differential rotational speed level for the lock-up clutch of the start-up element is determined on a control side when the decoupling of the lock-up clutch is requested, a magnitude of the first target differential rotational speed level being greater than zero.

3. The method of claim 2 , wherein a motor controller on the control side determines the first target differential rotational speed level for the lock-up clutch of the start-up element when the decoupling of the lock-up clutch is requested, the method further comprising determining a target differential rotational speed curve at the first target differential rotational speed level with a start-up element controller.

4. The method of claim 3 , wherein the start-up element controller determines a ramp-like curve of the target differential rotational speed at the first target differential rotational speed level.

5. The method of claim 2 , further comprising determining a second target differential rotational speed level for the lock-up clutch of the start-up element on the control side when the decoupling of the lock-up clutch is no longer requested, the second target differential rotational speed level being less than the first target differential rotational speed level, a magnitude of the second target differential rotational speed level being greater than or equal to zero.

6. The method of claim 5 , wherein the start-up element controller determines a ramp-like curve of the target differential rotational speed from the first target differential rotational speed level to the second target differential rotational speed level.

7. The method of claim 5 , wherein,
when the slip at the lock-up clutch reaches the threshold or is greater than the threshold, a curve of the target rotational speed is determined for the electric motor such that the target rotational speed is increased in a ramp-like manner from a current rotational speed of the electric motor to a rotational speed dependent on the first target differential rotational speed level of the lock-up clutch, which remains constant as long as the decoupling of the lock-up clutch is requested, and
when the decoupling of the lock-up clutch is no longer requested, the target rotational speed for the electric motor is reduced in a ramp-like manner from the current rotational speed to a rotational speed dependent on the second target differential rotational speed level of the lock-up clutch.

8. The method of claim 1 , wherein a torque transferred by the lock-up clutch is controlled to a driver requested torque when the driver requested torque changes during the requested decoupling of the lock-up clutch.

9. The method of claim 8 , wherein a target transmission input torque is calculated depending on the driver requested torque during the requested decoupling of the lock-up clutch, the torque transferred by the lock-up clutch adjusted such that an increase in a torque transferred by the converter caused by the slip of the lock-up clutch is compensated.

10. A control device for operating a drive train, the control device programmed to implement the method of claim 1 .

11. The method of claim 1 , wherein the decoupling of the lock-up clutch is requested during a startup of the internal combustion engine, and the electric motor is not rotationally speed controlled until the slip at the lock-up clutch reaches the threshold or is greater than the threshold during the startup of the internal combustion engine.

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Lemp Thomas
• Hess Christoph
• Platzer Falko

Classifications

• B60W2710/081

  Speed · CPC title

• B60W10/08

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

• B60K6/387

  Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means · CPC title

• B60K6/547

  the transmission being a stepped gearing · CPC title

• B60W10/026

  of lock-up clutches · CPC title