Speed change control method and apparatus for an automatic transmission for vehicles traveling under various road conditions
First Claim
1. A speed change control method for an automatic transmission which is provided on a vehicle and which has a plurality of gear positions including a lowest-speed gearshift position, comprising the steps of:
- (a) detecting a value of a parameter related to frictional resistance of a road surface on which the vehicle is traveling;
(b) detecting a start of the vehicle from a stop position; and
(c) prohibiting gearshift to said lowest-speed gearshift position if the frictional resistance of the road surface is judged to be low based on the value of the detected said related parameter at the time of detecting a start.
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Accused Products
Abstract
In a speed change control method for an automatic transmission for vehicles with a plurality of gearshift positions, the frictional resistance of a road surface is detected, gearshifting to at least a lowest-speed gearshift position is prohibited if the frictional resistance of the road surface is judged to be low. Preferably, gearshifting to at least the lowest-speed gearshift position is prohibited when starting the vehicle from a stopped position if the frictional resistance of the road surface is judged to be low. The frictional resistance of the road surface is determined to be low when an occurrence frequency (%) of the detected frictional resistance value, being less than or equal to a first predetermined value, is more than or equal to a second predetermined value.
29 Citations
11 Claims
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1. A speed change control method for an automatic transmission which is provided on a vehicle and which has a plurality of gear positions including a lowest-speed gearshift position, comprising the steps of:
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(a) detecting a value of a parameter related to frictional resistance of a road surface on which the vehicle is traveling; (b) detecting a start of the vehicle from a stop position; and (c) prohibiting gearshift to said lowest-speed gearshift position if the frictional resistance of the road surface is judged to be low based on the value of the detected said related parameter at the time of detecting a start. - View Dependent Claims (2, 3, 4, 5)
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6. A speed change control apparatus for an automatic transmission which is provided on a vehicle and which has a plurality of gear positions including a lowest-speed gearshift position, comprising:
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frictional resistance detecting means for detecting a value of a parameter related to frictional resistance of a road surface on which a vehicle is travelling; vehicle start detecting means for detecting a start of the vehicle from a stop position; and prohibiting means for prohibiting gearshift to said lowest-speed gear position if the frictional resistance of the road surface is judged to be low based on the detected value when the start of the vehicle is detected. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification