Shift control device and shift control method for vehicular automatic transmission

• US 6,761,664 B2
• Filed: 07/29/2002
• Issued: 07/13/2004
• Est. Priority Date: 07/27/2001
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Watanabe, Kazuyuki, Sato, Toshimitsu, Kimura, Hiromichi, Kato, Shinji, Sakamoto, Naoyuki, Hojo, Yasuo, Ayabe, Atsushi
• Primary Examiner(s): Marmor, Charles A
• Assistant Examiner(s): ABDELNOUR, DENNIS J
• Application Number:
  US10/206,238
• Publication Number:
  US 20030022756A1
• Time in Patent Office: 715 Days
• Field of Search: 477/115, 477/116, 477/140, 477/141, 477/144, 701/58
• US Class Current: 477/144
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: F16H 2061/0087 Adaptive control, e.g. the control parameters adapted by learning
• CPC Class Codes: F16H 2061/0444 during fast shifting over two gearsteps, e.g. jumping from fourth to second gear
• CPC Class Codes: F16H 2200/0047 the gear ratios comprising five forward speeds
• CPC Class Codes: F16H 2200/201 with three sets of orbital gears
• CPC Class Codes: F16H 2306/14 Skipping gear shift
• CPC Class Codes: F16H 3/64 composed of a number of gear trains, the drive always passing through all the trains, each train having not more than one connection for driving another train
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 61/686 with orbital gears

Abstract

When a current downshift is determined to be a multiple downshift, it is determined whether or not a torque down during a first downshift is in a condition of interfering with learning performed for stabilizing the downshift operation during a second downshift is executed. If the torque down during the first downshift is determined to be in the condition of interfering with the learning, the learning is prohibited.

Claims

1. A shift control device for an automatic transmission of a vehicle, comprising:

a first downshift control portion that executes a first downshift, while performing a torque down of an input torque to the automatic transmission so as to suppress a shift shock;

a second downshift control portion that executes a second downshift from a gear position reached in the first downshift;

a learning control portion that performs a learning control for stabilizing the downshift operation when the second downshift is executed by the second downshift control portion;

a multiple downshift determination portion that determines whether or not the current downshift is a multiple downshift in which the second downshift is started before the first downshift is completed;

a learning interference determination portion that determines whether or not the torque down during the first downshift is in a condition of interfering with the learning performed by the learning control portion when the multiple downshift determination portion determines that the current downshift is the multiple downshift; and

a learning prohibition portion that prohibits the learning performed by the learning control portion if the learning interference determination portion determines that the torque down during the first downshift is in the condition of interfering with the learning performed by the learning control portion.

2. The shift control device according to claim 1, wherein the learning interference determination portion determines that the torque down during the first downshift is in the condition of interfering with the learning performed by the learning control portion based on a fact that the first downshift has not been completed even when an elapsed time after the second downshift is started exceeds a predetermined value.

3. The shift control device according to claim 1, further comprising:

a learning variation determination portion that determines whether or not variations in the learning performed by the learning control portion for the second downshift are greater than a predetermined value; and

a torque down prohibition portion that prohibits the torque down in the first downshift if the learning variation determination portion determines that the variations in the learning in the second downshift are greater than the predetermined value.

4. The shift control device according to claim 1, further comprising:

a learning completion determination portion that determines whether or not a period of the learning performed by the learning control portion for the second downshift has been completed; and

a torque down prohibition portion that prohibits the torque down in the first downshift if the learning completion determination portion determines that the period of the learning performed by the learning control portion for the second downshift has not been completed.

5. The shift control device according to claim 4, wherein the learning completion determination portion determines that the period of the learning performed by the learning control portion for the second downshift has been completed based on at least one of a number of learning operations performed by the learning control portion, a drive time of a vehicle, and a distance driven by a vehicle.

6. The shift control device according to claim 1, wherein the second downshift is a clutch-to-clutch shift executed through a release operation of a hydraulic friction engagement device on a release side and an engagement operation of a hydraulic friction engagement device on an engagement side.

7. The shift control device according to claim 6, wherein the learning control portion adjusts an engagement pressure of the hydraulic friction engagement device on the engagement side so that a period from the start of the second downshift to a time at which the hydraulic friction engagement device on the release side starts slipping coincides with a predetermined target period.

8. The shift control device according to claim 7, wherein the learning interference determination portion determines whether or not the torque down during the first downshift is in a condition of interfering with the period up to the start of slippage when the multiple downshift determination portion determines that the current downshift is the multiple downshift, and the learning prohibition portion prohibits the learning performed by the learning control portion if the learning interference determination portion determines that the torque down during the first downshift is in the condition of interfering with the period up to the start of slippage.

9. The shift control device according to claim 8, further comprising:

a learning variation determination portion that determines whether or not the period up to the start of slippage as adjusted by the learning control portion is greater than a predetermined value; and

a torque down prohibition portion that prohibits the torque down in the first downshift if the learning variation determination portion determines that the period up to the start of slippage is greater than the predetermined value.

10. The shift control device according to claim 6, wherein the automatic transmission includes:

a main shift portion having a pair of a first planetary gear drive and a second planetary gear drive, each of which is formed by mutually connecting a carrier and a ring gear; and

an underdrive portion having a third planetary gear drive that changes the speed of an output from the main shift portion.

11. The shift control device according to claim 1, wherein the first downshift is a downshift from an nth speed to an (n−

1)th speed, and the second downshift is a downshift from the (n−

1)th speed to one of an (n−

2)th speed and an (n−

3)th speed.

12. A shift control method for an automatic transmission of a vehicle, comprising the steps of:

executing a first downshift, while performing a torque down of an input torque to the automatic transmission so as to suppress a shift shock;

executing a second downshift from a gear position reached in the first downshift;

performing a learning control during the execution of the second downshift for stabilizing the downshift operation;

determining whether or not the current downshift is a multiple downshift in which the second downshift is started before the first downshift is completed;

determining whether or not the torque down during the first downshift is in a condition of interfering with the learning when it is determined that the current downshift is the multiple downshift; and

prohibiting the learning if it is determined that the torque down during the first downshift is in the condition of interfering with the learning.

13. The shift control method according to claim 12, wherein it is determined that the torque down during the first downshift is in the condition of interfering with the learning, based on a fact that the first downshift has not been completed even when an elapsed time after the second downshift is started exceeds a predetermined value.

14. The shift control method according to claim 12, further comprising the steps of:

determining whether or not variations in the learning for the second downshift are greater than a predetermined value; and

prohibiting the torque down during the first downshift if it is determined that variations in the learning for the second downshift are greater than the predetermined value.

15. The shift control method according to claim 12, further comprising the steps of:

determining whether or not a period of the learning for the second downshift has been completed; and

prohibiting the torque down during the first downshift if it is determined that the period of the learning for the second downshift has not been completed.