Hybrid Powertrain with Efficient Electric-Only Mode

• US 20090036246A1
• Filed: 08/01/2007
• Published: 02/05/2009
• Est. Priority Date: 08/01/2007
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Holmes, Alan G., Bucknor, Norman K.
• Granted Patent: US 7,727,100 B2
• Time in Patent Office: Days
• US Class Current: 475/5
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: F16H 2037/0866 Power split variators with distributing differentials, with the output of the CVT connected or connectable to the output shaft
• CPC Class Codes: F16H 2200/2007 with two sets of orbital gears
• CPC Class Codes: F16H 2200/2035 with two engaging means
• CPC Class Codes: F16H 3/728 with means to change ratio in the mechanical gearing
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/907 Electricity storage, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/91 Orbital, e.g. planetary gears
• CPC Class Codes: Y10S 903/913 One way
• CPC Class Codes: Y10S 903/951 Assembly or relative location of components

Abstract

A hybrid powertrain includes a hybrid electromechanical transmission and a power source. A planetary gear set having a first, a second, and a third member connects the power source with a first and a second motor/generator. A battery is operatively connected to the motor/generators for receiving power therefrom and delivering power thereto. An input member rotates with the first member, the first motor/generator rotates with the second member, and the second motor/generator rotates with the output member. A first torque-transmitting mechanism is engagable to connect the second motor/generator for rotation with the third member. The battery and the second motor/generator provide an electric-only operating mode to power the output member when the first torque-transmitting mechanism is not engaged; the power source, planetary gear set and first motor/generator thereby being disconnected from the output member during the electric-only operating mode to prevent parasitic drag.

Claims

1. A hybrid electromechanical transmission connectable with a power source, comprising:

an input member connected with the power source;

an output member;

a planetary gear set having a first, a second, and a third member;

first and second motor/generators;

a battery operatively connected to the motor/generators for receiving power therefrom and delivering power thereto;

wherein the input member is operatively connected with the first member;

wherein the first motor/generator is operatively connected for rotation with the second member;

wherein the second motor/generator is operatively connected for rotation with the output member;

a first torque-transmitting mechanism engagable to connect the second motor/generator for rotation with the third member; and

wherein the battery and second motor/generator provide an electric-only operating mode to power the output member when the first torque-transmitting mechanism is not engaged;

the power source, planetary gear set and first motor/generator thereby being disconnected from the output member during the electric-only operating mode to prevent parasitic drag.

2. The hybrid electromechanical transmission of claim 1, wherein the first torque-transmitting mechanism is a one-way clutch that is automatically in a disengaged, overrunning state during the electric-only operating mode.

3. The hybrid electromechanical transmission of claim 1, wherein the first torque-transmitting mechanism is a selectively engagable clutch capable of transmitting torque in two directions.

4. The hybrid electromechanical transmission of claim 1, wherein the battery, the second motor/generator, and the power source provide an input-split operating mode in which the second motor/generator and the power source power the output member and the first torque-transmitting mechanism is engaged.

5. The hybrid electromechanical transmission of claim 1, further comprising:

a stationary member;

a second torque-transmitting mechanism engagable to ground the third member of the planetary gear set to a stationary member; and

wherein the power source, first motor/generator, and second motor/generator provide a series hybrid operating mode in which the second torque-transmitting mechanism is engaged and the power source is providing power, with the first motor/generator powered by the power source to operate as a generator to send electrical power to the second motor/generator via the battery, and with the second motor/generator operating as a motor.

6. The hybrid electromechanical transmission of claim 5, wherein the power source is an engine;

and wherein the second torque-transmitting mechanism brake capable of transmitting torque in two directions that selectively grounds the third member to the stationary member when the first motor/generator is operated as a motor to start the engine.

7. The hybrid electromechanical transmission of claim 5, wherein the second torque-transmitting mechanism is a one-way clutch.

8. The hybrid electromechanical transmission of claim 1, wherein the battery is configured to be connectable to an off-board power supply for recharging the battery.

9. A hybrid powertrain comprising:

an engine;

an electrically-variable transmission having;

an input member connected for rotation with the engine;

an output member;

a stationary member;

a planetary gear set having a ring gear member, a sun gear member, and a carrier member rotatably supporting a plurality of pinion gears that intermesh with both the ring gear member and the sun gear member;

first and second motor/generators;

wherein the first motor/generator is operatively connected for rotation with the sun gear member;

wherein the second motor/generator is operatively connected for rotation with the output member;

a battery operatively connected to the first and second motor/generators for receiving power therefrom and delivering power thereto;

wherein the battery is configured to be operatively connectable to an offboard power supply for recharging the battery;

a one-way clutch engagable to interconnect the ring gear member and the output member;

wherein the one-way clutch automatically engages when the ring gear member rotates in a forward direction and overruns when the ring gear member does not rotate;

a torque-transmitting mechanism engagable to ground the ring gear member to the stationary housing;

wherein the battery and the second motor/generator provide an electric-only operating mode when the one-way clutch is not engaged and the engine is off, the one-way clutch thus disconnecting the planetary gear set, the engine, and the first motor/generator from the output member during the electric-only operating mode;

wherein the engine, the battery, and the second/motor/generator provide an input-split operating mode when the engine is on, the one-way clutch is engaged, and the second torque-transmitting mechanism in not engaged; and

wherein the engine, the first motor/generator, the battery, and the second motor/generator provide a series hybrid operating mode when the engine is on, the one-way clutch is not engaged, and the second torque-transmitting mechanism is engaged.

10. A method of operating a hybrid electromechanical powertrain having an engine, a transmission with a first motor/generator, a second motor/generator, and a planetary gear set;

wherein the engine and the motor/generators are each connectable to different members of the planetary gear set, the method comprising;

providing a first engagable and disengagable torque-transmitting mechanism between the second motor/generator and the member of the planetary gear set connected with the second motor/generator;

directing stored electrical power to the second motor/generator to drive a transmission output member to thereby establish an electric-only operating mode; and

wherein the first torque-transmitting mechanism is disengaged during said directing such that the second motor/generator and output member are isolated from the engine, the planetary gear set, and the first motor/generator, thereby eliminating parasitic drag.

11. The method of claim 10, wherein the first torque-transmitting mechanism is a first one-way clutch such that the second motor/generator and output member are automatically isolated from the engine, the planetary gear set, and the first motor/generator during the electric-only operating mode due to overrunning of the one-way clutch.

12. The method of claim 10, further comprising:

powering the engine during said directing stored electrical power to the second motor/generator;

wherein the first torque-transmitting mechanism is engaged during said powering the engine to thereby establish an input-split operating mode.

13. The method of claim 12, wherein the first torque transmitting mechanism is a one-way clutch that automatically overruns during the electric-only operating mode and that automatically engages during the input-split operating mode.

14. The method of claim 12, further comprising:

selectively engaging a second torque-transmitting mechanism to ground the member of the planetary gear set connectable to the second motor/generator;

powering the engine; and

controlling the first motor/generator to act as a generator that provides the electric power to the battery, thereby establishing a series hybrid operating mode.

15. The method of claim 14, further comprising:

switching from the electric-only operating mode to the input-split operating mode by controlling the first motor/generator to operate as a motor, thereby synchronizing rotational speed of the member of the planetary gear set connectable with the second motor/generator with the rotational speed of the second motor/generator.