MOTOR LOCK PREVENTION CONTROL FOR HYBRID VEHICLE

• US 20080006457A1
• Filed: 07/03/2007
• Published: 01/10/2008
• Est. Priority Date: 07/05/2006
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Fujimoto, Satoru, Ashizawa, Hiroyuki, Adachi, Kazutaka
• Granted Patent: US 8,132,635 B2
• Time in Patent Office: Days
• US Class Current: 180/65.1
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• 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 2510/0275 Clutch torque
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 30/1843 Overheating of driveline components B60W30/186 takes precedence

Abstract

There is provided a motor lock prevention control device for a hybrid vehicle that has a motor-generator and a clutch capable of changing a transmission torque capacity between the motor-generator and driving wheels. The motor lock prevention control device is configured to, when the motor-generator is in a motor locked state to cause heat generation under drive load operating condition, perform motor prevention control to induce rotation of the motor-generator by adjusting at least one of the transmission torque capacity of the clutch and torque of the motor-generator in such a manner that the torque of the motor-generator exceeds the transmission torque capacity of the clutch.

Claims

1. A motor lock prevention control device for a hybrid vehicle, the hybrid vehicle having an engine and a motor-generator as a driving power source, a first clutch capable of changing a transmission torque capacity between the engine and the motor-generator and a second clutch capable of changing a transmission torque capacity between the motor-generator and driving wheels so as to establish an electric drive mode in which the vehicle is powered by the motor-generator, with the engine stopped, upon disengagement of the first clutch and engagement of the second clutch and to establish a hybrid drive mode in which the vehicle is powered by the engine and the motor-generator upon engagement of the first and second clutches,

the motor lock prevention control device being configured to:

when the motor-generator is in a motor locked state to cause heat generation under drive load operating condition, perform motor lock prevention control to induce rotation of the motor-generator by adjusting at least one of the transmission torque capacity of the second clutch and torque of the motor-generator in such a manner that the torque of the motor-generator exceeds the transmission torque capacity of the second clutch.

2. A motor lock prevention control device according to claim 1, wherein the motor lock prevention control device initiates the motor lock prevention control at a sufficient time to accomplish said rotation of the motor-generator before the heat generation reaches a maximum allowable level.

3. A motor lock prevention control device according to claim 1, wherein the motor lock prevention control device induces said rotation of the motor-generator by gradually decreasing the transmission torque capacity of the second clutch on the time series.

4. A motor lock prevention control device according to claim 1, wherein the motor lock prevention control device induces said rotation of the motor-generator by decreasing the transmission torque capacity of the second clutch to a certain level in an instant and then gradually decreasing the transmission torque capacity of the second clutch on the time series when a difference the transmission torque capacity of the second clutch and the torque of the motor-generator is larger than or equal to a given degree.

5. A motor lock prevention control device according to claim 1, wherein the motor lock prevention control device, after inducing said rotation of the motor-generator, increases a rotational speed of the motor-generator to a level corresponding to a motor unlocked state of the motor-generator.

6. A motor lock prevention control device according to claim 1, wherein motor lock prevention control device starts the engine upon engagement of the first clutch when the torque of the motor-generator exceeds a difference between a maximum motor torque and an engine starting torque.

7. A motor lock prevention control device according to claim 1, wherein the hybrid vehicle has a motor-generator energization control circuit to control energization of the motor-generator so that said heat generation is caused by continuous energization of the motor-generator in a specific phase of the motor-generator control circuit.

8. A motor lock prevention control device for a hybrid vehicle, the hybrid vehicle having a motor-generator and a start clutch capable of changing a transmission torque capacity between the motor-generator and driving wheels,

the motor lock prevention control device being configured to:

when the motor-generator is in a motor locked state to cause heat generation under drive load operating condition, perform motor prevention control to induce rotation of the motor-generator by adjusting at least one of the transmission torque capacity of the start clutch and torque of the motor-generator in such a manner that the torque of the motor-generator exceeds the transmission torque capacity of the start clutch.

9. A motor lock prevention control method for a hybrid vehicle, the hybrid vehicle having a motor-generator and a clutch capable of changing a transmission torque capacity between the motor-generator and driving wheels, the motor lock prevention control method comprising:

judging whether the motor-generator is in a motor locked state to cause heat generation under drive load operating condition; and

when the motor-generator is judged as being in the motor locked state to cause heat generation under drive load operating condition, performing motor prevention control to induce rotation of the motor-generator by adjusting at least one of the transmission torque capacity of the clutch and torque of the motor-generator in such a manner that the torque of the motor-generator exceeds the transmission torque capacity of the clutch.