METHOD AND APPARATUS TO CONTROL LAUNCH OF A VEHICLE HAVING AN ELECTRO-MECHANICAL TRANSMISSION

• US 20090118917A1
• Filed: 11/07/2007
• Published: 05/07/2009
• Est. Priority Date: 11/07/2007
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Heap, Anthony H., Hubbard, Gregory A., Sah, Jy-Jen F.
• Granted Patent: US 8,224,544 B2
• Time in Patent Office: Days
• US Class Current: 701/54
• 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 the first electrical machine to the driveline; and

,

selectively increasing an operating speed of the internal combustion engine and selectively actuating a clutch to transmit motive torque generated by the second electrical machine to the driveline when an operator torque request exceeds a predetermined threshold.

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 greater than predetermined thresholds.

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 selectively actuating the clutch to transmit motive torque generated by the second electrical machine to the driveline when an operator torque request exceeds a predetermined threshold comprises permitting slippage of the actuated clutch.

6. The method of claim 5, wherein permitting slippage of the actuated clutch comprises limiting the clutch slippage based upon thermal operating characteristics of the clutch.

7. The method of claim 6, further comprising selectively controlling oncoming clutch torque of the actuated clutch.

8. The method of claim 1, further comprising operating the electro-mechanical transmission in a fixed gear mode when engine speed substantially matches output speed of the transmission factored by a gear ratio of the fixed gear.

9. 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 the first electrical machine to the driveline; and

,

code to selectively increase an operating speed of the internal combustion engine and selectively actuate a clutch to transmit motive torque generated by the second electrical machine to the driveline when an operator torque request exceeds a predetermined threshold.

10. 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;

i) code to monitor an operator torque request during launch, and,

ii) code to operate the electro-mechanical transmission in a continuously variable mode transmitting motive torque from the first electrical machine; and

,

iii) code to selectively increase an operating speed of the internal combustion engine and selectively actuate a clutch to transmit motive torque generated by the second electrical machine to the driveline when an operator torque request exceeds a predetermined threshold.

11. The apparatus of claim 10, wherein the code to selectively actuate the clutch to transmit motive torque generated by the second electrical machine to the driveline when an operator torque request exceeds a predetermined threshold comprises code to permit slippage of the actuated clutch.

12. The apparatus of claim 11, wherein the code to permit slippage of the actuated clutch comprises code to limit the clutch slippage based upon thermal operating characteristics of the clutch.

13. The apparatus of claim 12, further comprising selectively controlling the flow control devices of the electro-hydraulic control circuit to selectively control oncoming clutch torque of the actuated clutch.