US 2003/0119631 A1 · CONTROL DEVICE OF AUTOMATIC TRANSMISSION

Abstract

In a process wherein a before-shifting gear ratio Gx changes to a gear ratio of the target gear position, an actual shift time is measured by regarding as a shift starting point an earlier one between a time point when the present gear ratio G has repeated decreasing by a value equal to or larger than a predetermined unit gear ratio ΔG a predetermined number of times N and a time point when the present gear ratio reaches a first gear ratio G1 that is set to a value smaller than the gear ratio Gx by a predetermined value. If the gear ratio changes rapidly, the start of shifting can be detected at a time ts1 when the present gear ratio G reaches the gear ratio G1, and if the gear ratio changes slowly, the start of shifting can be detected at a time ts4 when the gear ratio has repeated decreasing by a value equal to or larger than a predetermined unit gear ratio a predetermined number of times N. In either case, the start of shifting can be detected early at a point in proximity to a shift starting point ts. Further, a time point when the present gear ratio G reaches a second gear ratio, which is set to a value larger than the gear ratio Gx by a predetermined value, is also regarded as the shift starting point, so that the start of shifting can be detected early even in the case where an engine races. This enables accurate calculation of a shift time in shift time learning control for controlling working fluid pressure in an automatic transmission.

Claims6

Dependent claims

A control device of an automatic transmission, which selectively supplies hydraulic oil pressure to a plurality of friction engagement elements to change a plurality of gear positions by engaging and disengaging the friction engagement elements in combinations, said control device comprising:

an oil pressure regulating actuator for regulating the oil fluid pressure;
shift time learning control means for performing shift time learning control by comparing a target shift time and an actual shift time to thereby control said oil pressure regulating actuator;
and
wherein said shift time learning control means comprises gear ratio calculating means for finding a present gear ratio, and shift time measuring means for measuring the actual shift time by determining that shifting is started if the present gear ratio has repeated decreasing by a value equal to or larger than a predetermined unit gear ratio a predetermined number of times.

1 more element

Dependencies are inferred from the claim text.

Control device of automatic transmission

Life of this patent

Control device of automatic transmission

Life of this patent

Abstract

Claims6