Adjusting motor torque to enable slip of torque converter clutch to be maintained when accelerator pedal released in hybrid vehicle

• US 9,744,959 B2
• Filed: 05/07/2012
• Issued: 08/29/2017
• Est. Priority Date: 05/07/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Dai, Zhengyu, Grutter, Peter John, Huffmaster, Roger Lyle, Jiang, Hong, Nedorezov, Felix
• Primary Examiner(s): Hlavka, David J
• Application Number:
  US13/465,145
• Publication Number:
  US 20130296103A1
• Time in Patent Office: 1,940 Days
• Field of Search: 477 5, 477 3, 477 6, 477166, 477174, 477175, 477176, 477 53, 477 52, 477 62
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60W 10/026 of lock-up clutches
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• 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 2030/203 related or induced by the clutch
• CPC Class Codes: B60W 2510/0657 Engine torque
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/024 of torque converter lock-up clutch
• CPC Class Codes: B60W 2710/025 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: B60W 2710/026 Slip change rate
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: F16H 2061/145 for controlling slip, e.g. approaching target slip value
• CPC Class Codes: F16H 61/143 using electric control means
• CPC Class Codes: F16H 63/50 Signals to an engine or motor
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A controller and a control strategy for a hybrid electric vehicle having a traction motor between an engine and an automatic transmission include maintaining a bypass clutch of a torque converter in an engaged position and applying a motor torque from a traction motor to the torque converter such that slip of the torque converter does not otherwise reach zero while the bypass clutch is maintained in the engaged position.

Claims

1. A method of controlling a vehicle having a motor and a transmission having a torque converter with a clutch, comprising:

engaging the clutch to a partially-engaged position providing a non-zero slip;

while the clutch in response to a decrease in driver demand torque would otherwise move to a fully-engaged position providing a zero slip, controlling torque of the motor to increase the slip to be non-zero instead of disengaging the clutch to increase the slip.

2. The method of claim 1 wherein engaging comprises modulating a clutch pressure control signal to partially engage the clutch.

3. The method of claim 1 further comprising:

disengaging the clutch when the slip exceeds an associated threshold.

4. A system for controlling a hybrid vehicle having a traction motor between an engine and a transmission having a torque converter with a bypass clutch, comprising:

a controller configured to engage the bypass clutch to a partially-engaged position providing a non-zero slip and, while the clutch in response to a decrease in driver demand torque would otherwise approach a fully-engaged position providing a zero slip, control motor torque of the traction motor to increase the slip to be non-zero in lieu of disengaging the clutch being to increase the slip.

5. A hybrid electric vehicle comprising:

an electric motor;

a torque converter having a bypass clutch;

a controller configured to engage the bypass clutch to a partially-engaged position providing a non-zero slip and, while the clutch in response to a decrease in driver demand torque would otherwise approach a fully-engaged position providing a zero slip, apply a motor torque from the electric motor to increase the slip to be non-zero in lieu of disengaging the clutch to increase the slip.