Method and apparatus to control launch of a vehicle having an electro-mechanical transmission

• US 8,224,544 B2
• Filed: 11/07/2007
• Issued: 07/17/2012
• Est. Priority Date: 11/07/2007
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Sah, Jy-Jen F., Heap, Anthony H., Hubbard, Gregory A.
• Primary Examiner(s): Elchanti, Hussein
• Assistant Examiner(s): Khatib, Rami
• Application Number:
  US11/936,083
• Publication Number:
  US 20090118917A1
• Time in Patent Office: 1,714 Days
• Field of Search: 180 6521- 6529, 903/918, 701/22, 701 51- 69, 701/99
• US Class Current: 701/68
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 2240/507 Operating parameters
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• 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 10/115 with planetary gears
• 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 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 2050/0006 Digital architecture hierarchy
• CPC Class Codes: B60W 2510/0241 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: B60W 2510/0291 Clutch temperature
• CPC Class Codes: B60W 2555/20 Ambient conditions, e.g. wind or rain
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: B60W 30/1846 Preventing of breakage of drive line components, e.g. parts of the gearing
• CPC Class Codes: B60W 30/186 excessive wear or burn out of friction elements, e.g. clutches
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/918 : Continuously variable

Abstract

A method and apparatus to control an electro-mechanical transmission is provided, selectively operative in a plurality of fixed gear modes and continuously variable modes, and comprising first and second electrical machines and hydraulically-actuated clutches. Included is launching a vehicle so equipped, comprising operating the electro-mechanical transmission in a continuously variable mode to transmit motive torque from the first electrical machine to the driveline, and, selectively increasing an operating speed of the engine and selectively actuating a second clutch to transmit motive torque generated by the second electrical machine when an operator torque request exceeds a predetermined threshold.

Claims

1. Method to launch a vehicle including a powertrain comprising an internal combustion engine and first and second electrical machines and an electro-mechanical transmission selectively operative to transmit torque to a driveline, comprising:

operating the electro-mechanical transmission in a continuously variable mode to transmit motive torque from a first electrical machine to the driveline, the first electrical machine mechanically independent and decoupled from the internal combustion engine and the internal combustion engine mechanically independent and decoupled from the driveline when a clutch is selectively released;

selectively increasing an operating speed of the internal combustion engine independently from the driveline speed when an operator torque request exceeds a predetermined threshold, the increased operating speed of the internal combustion engine providing increased power input to the second electrical machine to generate electrical energy transmitted to the first electrical machine to facilitate increased motive torque from the first electrical machine to the driveline and pressurizing the clutch for a subsequent actuation; and

subsequent to selectively increasing the operating speed of the internal combustion engine and pressurizing the clutch, partially actuating the clutch providing partial coupling of the second electrical machine and the internal combustion engine to the driveline to transmit motive torque generated by the second electrical machine and the internal combustion engine to the driveline through a controlled clutch torque wherein the clutch is slipping, the clutch slippage increasing the driveline speed towards the increased engine operating speed to meet the operator torque request.

2. The method of claim 1, wherein the operator torque request exceeding a predetermined threshold comprises the operator depressing an accelerator pedal to a substantially wide open throttle position.

3. The method of claim 1, wherein the operator torque request exceeding a predetermined threshold comprises the operator simultaneously depressing an accelerator pedal and a brake pedal at a vehicle speed of zero.

4. The method of claim 1, wherein selectively increasing the operating speed of the internal combustion engine comprises operating the engine at an engine speed substantially greater than an optimum engine speed based upon torque and power demands.

5. The method of claim 1, wherein permitting slippage of the controlled clutch torque wherein the clutch is slipping comprises limiting the clutch slippage based upon thermal operating characteristics of the clutch.

6. The method of claim 1, further comprising fully actuating the clutch wherein the clutch is not slipping when engine speed substantially matches an output speed of the transmission factored by a gear ratio of a fixed gear to operate the electro-mechanical transmission in a fixed gear mode.

7. Article of manufacture, comprising a storage medium having a computer program encoded therein for effecting a launch of a vehicle having a powertrain comprising an internal combustion engine and first and second electrical machines and an electro-mechanical transmission selectively operative to transmit torque to a driveline, the computer program comprising:

code to operate the electro-mechanical transmission in a continuously variable mode to transmit motive torque from a first electrical machine to the driveline, the first electric machine mechanically independent and decoupled from the internal combustion engine and the internal combustion engine mechanically independent and decoupled from the driveline when a clutch is selectively released;

code to selectively increase an operating speed of the internal combustion engine independently from the driveline speed when an operator torque request exceeds a predetermined threshold, the increased operation speed of the internal combustion engine pressurizing the clutch for a subsequent actuation; and

code to partially actuate the clutch providing partial coupling of the second electrical machine and the internal combustion engine to the driveline to transmit motive torque generated by the second electrical machine and the internal combustion engine to the driveline through a controlled clutch torque wherein the clutch is slipping subsequent to selectively increasing the operating speed of the internal combustion engine, the clutch slippage increasing the driveline speed towards the increased engine operating speed to meet the operator torque request.

8. Apparatus, comprising:

an internal combustion engine and first and second electrical machines and an electro-mechanical transmission selectively operative to transmit torque therebetween and to a driveline;

the transmission comprising;

an electro-hydraulic control circuit comprising a plurality of pressure monitoring devices and a plurality of selectively controllable flow control devices, and, a plurality of torque-transfer clutches;

the transmission selectively operative in one of a plurality of operating modes comprising fixed gear ratio modes and two continuously variable modes; and

,

a control system;

adapted to control the flow control devices of the electro-hydraulic control circuit; and

,

adapted to execute a computer program to selectively control the flow control devices of the electro-hydraulic control circuit during vehicle launch, the program comprising;

code to monitor an operator torque request during launch;

code to operate the electro-mechanical transmission in a continuously variable mode transmitting motive torque from a first electrical machine to the driveline, the first electric machine mechanically independent and decoupled from the internal combustion engine and the internal combustion engine mechanically independent and decoupled from the driveline when a clutch is selectively released;

code to selectively increase an operating speed of the internal combustion engine independently from the driveline speed when an operator torque request exceeds a predetermined threshold, the increased operating speed of the internal combustion engine pressurizing the clutch for a subsequent actuation;

code to partially actuate a clutch providing partial coupling of the second electrical machine and the internal combustion engine to the driveline to transmit motive torque generated by the second electrical machine and the internal combustion engine to the driveline through a controlled clutch torque wherein the clutch is slipping subsequent to selectively increasing the operating speed of the internal combustion engine, the increased operating speed of the internal combustion engine pressurizing the clutch for a subsequent actuation; and

code to fully actuate the clutch wherein the clutch is not slipping when engine speed substantially matches an output speed of the transmission factored by a gear ratio of a fixed gear to operate the electro-mechanical transmission in a fixed gear mode.

9. The apparatus of claim 8, wherein the code to partially actuate the clutch comprises code to limit the clutch slippage based upon thermal operating characteristics of the clutch.