HYBRID POWERTRAIN WITH TORQUE-MULTIPLYING ENGINE STARTING MECHANISM AND METHOD OF CONTROLLING A HYBRID POWERTRAIN

• US 20100304924A1
• Filed: 05/26/2009
• Published: 12/02/2010
• Est. Priority Date: 05/26/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Bucknor, Norman K., Smith, Anthony L.
• Granted Patent: US 8,087,483 B2
• Time in Patent Office: Days
• US Class Current: 477/5
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 2006/4833 Step up or reduction gearing driving generator, e.g. to operate generator in most efficient speed range
• CPC Class Codes: B60K 6/36 characterised by the transmission gearings
• CPC Class Codes: B60K 6/387 Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 2240/423 Torque
• 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 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 2510/0604 Throttle position
• CPC Class Codes: B60W 2520/28 Wheel speed
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y10S 903/909 Gearing

Abstract

A hybrid powertrain is provided that provides engine starting from an electric-only mode with a reduced torque load on the motor/generator. The powertrain includes an engine and a motor/generator, which may be a single motor/generator in a strong or full hybrid, but is not limited to such. The motor provides propulsion torque in an electric-only operating mode, and is configured to apply torque to a transmission input member. A first clutch is selectively engagable to connect the engine output member for common rotation with the transmission input member. An engine starting mechanism is provided that multiplies motor torque used to start the engine so that less is diverted from propelling the vehicle, enabling a smaller motor/generator to be used. A method of controlling such a powertrain is also provided.

Claims

1. A hybrid powertrain comprising:

an engine with an engine output member;

a transmission with a transmission input member;

a motor/generator configured to apply torque to the transmission input member;

a first clutch selectively engagable to connect the engine output member for common rotation with the transmission input member; and

an engine starting mechanism including;

a first and a second gear train; and

a second clutch having a first portion connected with the transmission input member via the first gear train and a second portion connected with the engine output member via the second gear train, and selectively engagable to transfer torque from the transmission input member to the engine output member with torque multiplication.

2. The powertrain of claim 1, wherein the first gear train includes a first gear connected for rotation with the transmission input member and a second gear meshing with the first gear and connected for rotation with the first portion of the second clutch.

3. The powertrain of claim 1, wherein the second gear train includes a third gear connected for rotation with the second portion of the second clutch and a fourth gear meshing with the third gear and connected for rotation with the engine output member;

and wherein the fourth gear is larger than the third gear to cause the torque multiplication.

4. The powertrain of claim 1, wherein the second clutch is an active material clutch.

5. The powertrain of claim 4, wherein the second clutch is a magnetorheological clutch.

6. The powertrain of claim 1, wherein the first clutch is a hydraulic clutch.

7. The powertrain of claim 1, wherein the powertrain is operable in an electric-only operating mode, and wherein the first clutch is engagable during the electric only operating mode to establish a hybrid operating mode.

8. A method of controlling a hybrid powertrain having an engine with an engine output member, a transmission with a transmission input member, a motor/generator configured to apply torque to the transmission input member, and a first clutch selectively engagable to connect the engine output member for common rotation with the transmission input member;

the method comprising;

engaging a second clutch to transfer torque from the motor/generator to the engine to start the engine during an electric-only operating mode;

wherein the second clutch connects the motor/generator to the engine via gear trains configured to multiply motor torque.

9. The method of claim 8, further comprising:

releasing the second clutch after the engine is started.

10. The method of claim 8, further comprising:

synchronizing speed of the engine output member with speed of the transmission input member; and

engaging the first clutch after the synchronizing to thereby transfer engine torque to the transmission input member.

11. The method of claim 8, wherein engaging the second clutch includes applying an electric or magnetic field to the second clutch.

12. A hybrid powertrain comprising:

an engine with an engine output member;

a transmission with a transmission input member;

a motor/generator configured to apply torque to the transmission input member;

a hydraulically-actuated friction plate clutch selectively engagable to connect the engine output member for common rotation with the transmission input member;

an active material clutch having a first portion connected with the transmission input member via a first gear train and a second portion connected with the engine output member via a second gear train, and selectively engagable to transfer torque from the transmission input member to the engine output member with torque multiplication;

wherein the first gear train includes a first gear connected for rotation the transmission input member and a second gear connected for rotation with the first portion of the active material clutch;

wherein the second gear train includes a spur gear connected for rotation with the second portion of the second clutch and meshing with a ring gear connected for rotation with the engine output member;

wherein the gear ratio of the ring gear to the spur gear is greater than the gear ratio of the second gear to the first gear.