Vehicle transmission control apparatus

• US 6,497,635 B2
• Filed: 02/26/2001
• Issued: 12/24/2002
• Est. Priority Date: 03/23/2000
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Suzuki, Naoto
• Primary Examiner(s): Estremsky, Sherry
• Assistant Examiner(s): Lewis, Tisha D.
• Application Number:
  US09/791,581
• Publication Number:
  US 20010023666A1
• Time in Patent Office: 666 Days
• Field of Search: 477/3, 477/4, 477/15, 477/20, 477/29, 180/65.2, 180/65.3
• US Class Current: 477/3
• CPC Class Codes: B60K 6/36 characterised by the transmission gearings
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2260/22 Standstill, e.g. zero speed
• CPC Class Codes: B60L 2260/26 Transition between different drive modes
• 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 10/10 including control of change-speed gearings
• 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 2510/0638 Engine speed
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/065 Idle condition
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 30/18054 at stand still, e.g. engine in idling state hill holding B60W30/18118
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/919 : Stepped shift
• CPC Class Codes: Y10S 903/945 : Characterized by control of gearing, e.g. control of transmission ratio
• CPC Class Codes: Y10S 903/946 : Characterized by control of driveline clutch

Abstract

A transmission control apparatus is used with a vehicle having an internal combustion engine, a transmission connected to the engine and having a plurality of gear positions, and a generator which is disposed between the transmission and drive wheels and which is capable of generating electric power through regenerative braking during deceleration of the vehicle. The control apparatus operates to detect a revolution speed of the internal combustion engine, and to place the transmission in a highest gear position selected from one or more gear positions that enable the engine revolution speed to be maintained at a level not lower than a predetermined lower limit above which the engine can operate by itself (i.e., re-start), when the generator generates electric power through regenerative braking.

Claims

1. A transmission control apparatus of a vehicle that includes an internal combustion engine, a transmission connected to the internal combustion engine and having a plurality of gear positions with respective gear ratios, and a generator disposed between the transmission and drive wheels, the generator being capable of generating electric power through regenerative braking during deceleration of the vehicle, the transmission control apparatus comprising:

a detector that detects a revolution speed of the internal combustion engine; and

a shift controller that places the transmission in a highest gear position selected from one or more gear positions that enable the engine revolution speed to be maintained at a level not lower than a predetermined lower limit above which the engine can be re-started, when the generator generates electric power through regenerative braking.

2. A transmission control apparatus according to claim 1, wherein the shift controller determines whether the revolution speed of the engine is higher than the predetermined lower limit, and shifts down the transmission by one gear position when the revolution speed of the engine is not higher than the predetermined lower limit.

3. A transmission control apparatus according to claim 1, wherein the vehicle further includes a clutch disposed between the transmission and the engine, and wherein the shift controller operates to release the clutch so as to disconnect the internal combustion engine and the transmission from each other, when the selected highest gear position is the lowest one of said plurality of gear positions of the transmission.

4. A transmission control apparatus according to claim 1, wherein the vehicle further includes a clutch disposed between the transmission and the engine, and wherein the shift controller operates to release the clutch so as to disconnect the internal combustion engine and the transmission from each other, when there are no gear positions that enable the engine revolution speed to be maintained at a level not lower than the predetermined lower limit.

5. A method of controlling a transmission of a vehicle that includes an internal combustion engine, a transmission connected to the internal combustion engine and having a plurality of gear positions with respective gear ratios, and a generator disposed between the transmission and drive wheels, the generator being capable of generating electric power through regenerative braking during deceleration of the vehicle, the method comprising:

detecting a revolution speed of the internal combustion engine; and

placing the transmission in a highest gear position selected from one or more gear positions that enable the engine revolution speed to be maintained at a level not lower than a predetermined lower limit above which the engine can be re-started, when the generator generates electric power through regenerative braking.

6. A method according to claim 5, wherein said step of placing the transmission in a highest gear position comprises sub-steps of determining whether the revolution speed of the engine is higher than the predetermined lower limit, and shifting down the transmission by one gear position when the revolution speed of the engine is not higher than the predetermined lower limit.

7. A method according to claim 5, wherein the vehicle further includes a clutch disposed between the transmission and the engine, and further comprising:

disconnecting the internal combustion engine and the transmission from each other by releasing the clutch when the selected highest gear position is the lowest one of said plurality of gear positions of the transmission.

8. A method according to claim 5, wherein the vehicle further includes a clutch disposed between the transmission and the engine, and further comprising:

disconnecting the internal combustion engine and the transmission from each other by releasing the clutch when there are no gear positions that enable the engine revolution speed to be maintained at a level not lower than the predetermined lower limit.

9. In a hybrid vehicle that includes an internal combustion engine, a detector that detects a revolution speed of the internal combustion engine, a transmission connected to the internal combustion engine and having a plurality of gear positions with respective gear ratios, and a generator disposed between the transmission and drive wheels, the generator being capable of generating electric power through regenerative braking during deceleration of the vehicle, a transmission control apparatus comprising:

a shift controller that;

(i) determines a highest gear position, selected from one or more gear positions of the transmission, that enable the engine revolution speed to be maintained at a level not lower than a predetermined lower limit, and (ii) places the transmission in the determined highest gear position when the generator generates electric power through regenerative braking.

10. In a hybrid vehicle according to claim 9, wherein the shift controller determines whether the revolution speed of the engine is higher than the predetermined lower limit, and shifts down the transmission by one gear position when the revolution speed of the engine is not higher than the predetermined lower limit.

11. In a hybrid vehicle according to claim 9, wherein the vehicle further includes a clutch disposed between the transmission and the engine, and wherein the shift controller operates to release the clutch so as to disconnect the internal combustion engine and the transmission from each other, when the determined highest gear position is the lowest one of said plurality of gear positions of the transmission.

12. In a hybrid vehicle according to claim 9, wherein the vehicle further includes a clutch disposed between the transmission and the engine, and wherein the shift controller operates to release the clutch so as to disconnect the internal combustion engine and the transmission from each other, when there are no gear positions that enable the engine revolution speed to be maintained at a level not lower than the predetermined lower limit.