Shift control method of automatic transmission

• US 20070118267A1
• Filed: 12/26/2006
• Published: 05/24/2007
• Est. Priority Date: 04/07/2006
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Inventors: Yu, Pyung
• Granted Patent: US 7,765,047 B2
• Time in Patent Office: Days
• US Class Current: 701/57
• CPC Class Codes: F16H 2059/663 Road slope
• CPC Class Codes: F16H 2061/0081 Fuzzy logic
• CPC Class Codes: F16H 59/66 Road conditions, e.g. slope, slippery
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals

Abstract

A shift control method of an automatic transmission includes the steps of: determining whether a road has a gradient; calculating road gradient in real time; filtering the gradient; controlling shifting according to the greater of calculated and filtered gradients if the calculated gradient is negative; and controlling shifting according to the calculated gradient if the calculated gradient is positive.

Claims

1. A shift control method of an automatic transmission comprising:

a gradient determining step comprising determining whether a road has a gradient;

a gradient calculating step comprising, if the road is determined to have the gradient, calculating the gradient of the road in real time, and outputting a calculated gradient;

a gradient filtering step comprising filtering the calculated gradient and outputting a filtered gradient; and

a first shift controlling step comprising comparing the calculated gradient to the filtered gradient, outputting a greater gradient, and controlling shifting according to the greater gradient.

2. The method of claim 1, wherein the first shift controlling step is performed only if the calculated gradient is negative.

3. The method of claim 2, further comprising a second shifting controlling step comprising controlling shifting according to the calculated gradient if the calculated gradient is positive.

4. The method of claim 3, wherein the first shift controlling step is performed when the calculated gradient changes to negative after the second shift controlling step is performed.

5. The method of claim 1, wherein the gradient filtering step further comprises averaging a plurality of calculated gradients calculated during a predetermined time period.

6. The method of claim 1, wherein the gradient calculating step further comprises calculation of the gradient based on a difference between acceleration on a flat road and that on the road.

7. The method of claim 1, wherein the first shift controlling step further comprises inputting a throttle opening and a vehicle speed.

8. The method of claim 7, wherein the first shift controlling step further comprises fuzzy logic that determines a shift pattern based on the greater gradient, the throttle opening, and the vehicle speed.

9. The method of claim 3, wherein the second shift controlling step further comprises inputting a throttle opening and a vehicle speed.

10. The method of claim 9, wherein the second shift controlling step further comprises fuzzy logic that determines a shift pattern based on the calculated gradient, the throttle opening, and the vehicle speed.