Method for carrying out a load shift in a parallel hybrid vehicle during hybrid operation

• US 8,251,865 B2
• Filed: 08/08/2008
• Issued: 08/28/2012
• Est. Priority Date: 08/16/2007
• Status: Expired due to Fees

• Current Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Kaltenbach, Johannes, Wallner, Stefan
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US12/671,129
• Publication Number:
  US 20100210410A1
• Time in Patent Office: 1,481 Days
• Field of Search: None
• US Class Current: 477/5
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/113 with two input flow paths, e.g. double clutch transmission selection of one of the torque flow paths by the corresponding input clutch
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: B60Y 2400/428 Double clutch arrangements; Dual clutches
• CPC Class Codes: F16H 2061/0422 by an electric machine, e.g. by accelerating or braking the input shaft
• CPC Class Codes: F16H 2306/54 Synchronizing engine speed to transmission input speed
• CPC Class Codes: F16H 61/0403 Synchronisation before shifting
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method of carrying out a shift under load during hybrid operation in a parallel hybrid vehicle in which the speed adaptation of the electric machine and the internal combustion engine, required for synchronization to the new gear, is carried out by adapting the speed of the electric machine in a speed regulation mode.

Claims

1. A method of carrying out a shift under load during hybrid operation in a parallel hybrid vehicle, the method comprising the steps of:

adjusting a transmission capacity of a new clutch (K_neu) to be engaged to take up the load and, at the same time, adjusting a transmission capacity of an old clutch (K_alt) to be disengaged;

carrying out speed adaptation of an electric machine (2) and an internal combustion engine (1), required for synchronization to a new gear, by adapting a speed of the electric machine (2) in a speed regulation mode; and

only acting upon the internal combustion engine (1) if the electric machine (2) cannot supply sufficient torque to comply with the desired speed adaptation or nominal speed variation.

2. The method of carrying out a load shift according to claim 1, further comprising the step of designing the speed variation such that the speed (n_EM) of the electric machine (2) approaches a target speed (n_Gang_neu) with a low gradient.

3. The method of carrying out a load shift according to claim 2, further comprising the step of having torques of shift elements (K_alt, K_neu) and a torque of the internal combustion engine (1), acting on the electric machine (2), serve as a pre-control for the speed regulation of the electric machine (2).

4. The method of carrying out a load shift according to claim 3, further comprising the step of returning the electric machine (2) to a torque-controlled mode and completely engaging a shift element (K_neu) when the speed (n_EM) of the electric machine (2) reaches either the target speed or a synchronous speed (n_Gang_neu) of the gear to be engaged.

5. The method of carrying out a load shift according to claim 1, further comprising the steps of

increasing, in a traction upshift, the transmission capacity of a new clutch (K_neu) to be engaged to take up the load and, at the same time, reducing the transmission capacity of an old clutch (K_alt) to be disengaged;

and

changing the electric machine (2) to a speed regulation mode, when the load has been taken up by the new clutch (K_neu) being engaged;

adapting the speed of the electric machine (2) so as to reach the synchronous speed of the gear to be engaged, such that under speed regulation, the electric machine (2) is adjusted to either a target speed or a synchronous speed of the new gear and, at the same time, the old clutch (K_alt) being disengaged is disengaged completely.

6. The method of carrying out a load shift according to claim 1, further comprising the steps of

reducing, in a traction downshift, the transmission capacity of the shift element (K_alt) to be disengaged;

changing the electric machine (2) from a torque-controlled mode to a speed regulation mode as soon as slip is detected in the shift element (K_alt) being disengaged, in which the speed of the electric machine (2) is increased to a speed higher than a synchronous speed of the shift element (K_neu) to be engaged; and

increasing the transmission capacity of the shift element (K_neu) to be engaged and reducing further the transmission capacity of the shift element (K_alt) being disengaged, such that a continuous load uptake by the shift element (K_neu) being engaged takes place; and

on completion of load uptake by the shift element (K_neu) being engaged, completely disengaging the shift element (K_alt) being disengaged and adjusting the speed of the electric machine (2) to the synchronous speed of the shift element (K_neu) being engaged.

7. The method of carrying out a load shift according to claim 1, further comprising the step of:

increasing, in a thrust downshift, the transmission capacity of the shift element (K_neu) to be engaged and, at the same time, reducing the transmission capacity of the clutch (K_alt) to be disengaged;

changing the electric machine (2) from the torque-controlled mode to a speed regulation mode after load uptake by the shift element (K_neu) being engaged and substantially disengaging the shift element (K_alt) being disengaged; and

adjusting the electric machine (2) under the speed regulation mode to a synchronous speed and, at the same time, completely disengaging the shift element (K_alt) being disengaged.

8. The method of carrying out a load shift according to claim 1, further comprising the steps of:

continuously reducing, in a thrust upshift, the transmission capacity of the shift element (K_alt) to be disengaged;

changing the electric machine (2) from a torque-controlled mode to a speed regulation mode as soon as slip is detected at the shift element (K_alt) being disengaged, in which the of the electric machine (2) speed is reduced to a value lower than a synchronous speed at the shift element (K_neu) to be engaged;

increasing the transmission capacity of the shift element (K_neu) to be engaged and reducing the transmission capacity of the shift element (K_alt) being disengaged so that a continuous load uptake by the shift element (K_neu) to be engaged takes place; and

completely disengaging the shift element (K_alt) being disengaged, on completion of the load uptake by the shift element (K_neu) being engaged, and adjusting the speed of the electric machine (2) in the speed regulation mode to the synchronous speed of the shift element (K_neu) being engaged.

9. A method of carrying out at least one of a thrust upshift and a traction downshift under load during hybrid operation in a parallel hybrid vehicle, the method comprising the steps of:

initiating at least one of the thrust upshift and the traction downshift

adjusting a transmission capacity of a new clutch (K_neu) to be engaged to take up the load, the new clutch corresponding to a new gear to be engaged and, at the same time, adjusting a transmission capacity of an old clutch (K_alt) to be disengaged, the old clutch corresponding to an old gear to be disengaged;

carrying out speed adaptation of an electric machine (2) and an internal combustion engine (1), required for synchronization to the new gear, by adapting a speed of the electric machine (2) in a speed regulation mode; and

only acting upon the internal combustion engine (1) if the electric machine (2) cannot supply sufficient torque to comply with the desired speed adaptation or nominal speed variation.