Method and apparatus for controlling a powertrain system during deceleration

Patent metadata

Field	Value
Publication number	US-9669835-B2
Application number	US-201514923593-A
Country	US
Kind code	B2
Filing date	Oct 27, 2015
Priority date	Oct 27, 2015
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

A method for controlling a powertrain includes, in response to an output torque request that includes deceleration, operating an internal combustion engine in a fuel cutoff state and in a cylinder deactivation state, controlling a clutch of a torque converter in an activated state, and operating an electric machine in a regenerative braking state. A state of the powertrain related to engine speed is monitored. The internal combustion engine is commanded to transition from the cylinder deactivation state to an all-cylinder state and the electric machine operates in the regenerative braking state including ramping down magnitude of regenerative braking torque when the engine speed is less than a first threshold speed. The torque converter clutch is commanded to a released state when the engine speed is less than a second threshold speed, with the first threshold speed being greater than the second threshold speed.

First claim

The invention claimed is:

1. A method for controlling a powertrain including an internal combustion engine and an electric machine rotatably coupled via a torque converter to a transmission, wherein an output member of the transmission is rotatably coupled to a driveline, the method comprising:
in response to an output torque request that includes deceleration:
operating the internal combustion engine in a fuel cutoff state and in a cylinder deactivation state, controlling a clutch of the torque converter in an activated state, and operating the electric machine in a regenerative braking state;
monitoring a state of the powertrain related to engine speed; commanding the internal combustion engine to transition from the cylinder deactivation state to an all-cylinder state and operating the electric machine in the regenerative braking state including ramping down magnitude of regenerative braking torque when the engine speed is less than a first threshold speed; and
commanding the torque converter clutch to a released state when the engine speed is less than a second threshold speed;
wherein the first threshold speed is greater than the second threshold speed.

2. The method of claim 1 , wherein the first threshold speed and the second threshold speed are determined based upon a rate of change in the engine speed.

3. The method of claim 1 , wherein the first threshold speed is determined based upon a minimum permissible speed for operating the engine in the cylinder deactivation state.

4. The method of claim 1 , wherein the second threshold speed is determined based upon a minimum permissible speed for operating the engine in the all-cylinder state in conjunction with the fuel cutoff state.

5. The method of claim 1 , further comprising ramping down the magnitude of regenerative braking torque such that the regenerative braking torque achieves zero torque coincident with the commanding the torque converter clutch to the released state.

6. The method of claim 1 , wherein monitoring a state of the powertrain related to engine speed comprises monitoring an input speed to the transmission.

7. The method of claim 1 , wherein commanding the internal combustion engine to transition from the cylinder deactivation state to the all-cylinder state comprises commanding the internal combustion engine to transition from the cylinder deactivation state to the all-cylinder state while operating the engine in the fuel cutoff state.

8. A method for controlling an internal combustion engine, an electric machine and a clutch of a torque converter, wherein the engine and electric machine rotatably couple via the torque converter to a transmission having an output member rotatably coupled to a vehicle driveline, the method comprising:
commanding operation of the internal combustion engine in a fuel cutoff state and in a cylinder deactivation state, controlling a clutch of the torque converter in an activated state, and operating the electric machine in a regenerative braking state in response to an output torque request that includes deceleration;
commanding the internal combustion engine to transition from the cylinder deactivation state to an all-cylinder state when engine speed is less than a first threshold speed, and ramping down regenerative braking torque when engine speed is less than a first threshold speed; and
commanding release of the torque converter clutch when the engine speed is less than a second threshold speed that is less than the first threshold speed.

9. The method of claim 8 , wherein the first threshold speed and the second threshold speed are determined based upon a rate of change in the engine speed.

10. The method of claim 8 , wherein the first threshold speed is determined based upon a minimum permissible speed for operating the engine in the cylinder deactivation state.

11. The method of claim 8 , wherein the second threshold speed is determined based upon a minimum permissible speed for operating the engine in the all-cylinder state in conjunction with the fuel cutoff state.

12. The method of claim 8 , further comprising ramping down the magnitude of regenerative braking torque such that the regenerative braking torque achieves zero torque coincident with a release of the torque converter clutch.

13. The method of claim 8 , wherein commanding the internal combustion engine to transition from the cylinder deactivation state to the all-cylinder state comprises commanding the internal combustion engine to transition from the cylinder deactivation state to the all-cylinder state while operating the engine in the fuel cutoff state.

14. A powertrain system, comprising:
an internal combustion engine;
an electric machine rotatably coupled to the internal combustion engine;
a torque converter including a controllable clutch;
a transmission having an output member rotatably coupled to a driveline; and
a controller, operatively connected to the internal combustion engine, the torque converter, and the electric machine, the controller including an instruction set, the instruction set executable to:
monitor an output torque request,
determine engine speed,
command the internal combustion engine to operate in a fuel cutoff state and in a cylinder deactivation state, control the torque converter clutch in an activated state, and operate the electric machine in a regenerative braking state when the output torque request includes deceleration,
command the internal combustion engine to transition from the cylinder deactivation state to an all-cylinder state when the engine speed is less than a first threshold speed,
ramp down regenerative braking torque when the engine speed is less than a first threshold speed, and
command the torque converter clutch to a released state when the engine speed is less than a second threshold speed that is less than the first threshold speed.

15. The powertrain system of claim 14 , wherein the command to the internal combustion engine to transition from the cylinder deactivation state to the all-cylinder state comprises a command to the internal combustion engine to transition from the cylinder deactivation state to the all-cylinder state while operating the engine in the fuel cutoff state.

16. The powertrain system of claim 14 , wherein the first threshold speed and the second threshold speed are determined based upon a rate of change in the engine speed.

17. The powertrain system of claim 14 , wherein the first threshold speed is determined based upon a minimum permissible speed for operating the engine in the cylinder deactivation state.

18. The powertrain system of claim 14 , wherein the second threshold speed is determined based upon a minimum permissible speed for operating the engine in the all-cylinder state in conjunction with the fuel cutoff state.

19. The powertrain system of claim 14 , further comprising the instruction set executable to ramp down the magnitude of regenerative braking torque such that the regenerative braking torque achieves zero torque coincident with the command to the torque converter clutch to the released state.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Kim Kee Yong
• Heap Anthony H
• Miller Michael Andrew
• Shepley Luke D
• Woon Michael Vincent

Classifications

• B60K6/20

  the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs · CPC title

• B60Y2300/91

  Battery charging · CPC title

• Y10T477/735

  Cross-Sectional Technologies · mapped topic

• B60T1/10

  by utilising wheel movement for accumulating energy, e.g. driving air compressors · CPC title

• Y10T477/6422

  Cross-Sectional Technologies · mapped topic