Step automatic transmission

Abstract

An automatic transmission of a motor vehicle, comprising a plurality of planetary gear units; a plurality of frictional elements, the frictional elements assuming engaged / disengaged condition upon receiving a ratio change instruction thereby to establish a desired speed of the transmission with the aid of the planetary gear units; a deceleration detecting means that detects a deceleration of the motor vehicle; a gear ratio detecting means that detects an actual gear ratio that is actually established in the transmission; and an interlock judgment means that judges whether or not the transmission is subjected to an interlock, the interlock being a condition wherein upon receiving the ratio change instruction, at least one of the frictional elements is brought into unintended engagement. The interlock judgment means is configured to carry out judgment of the interlock by analyzing a deceleration of the vehicle and a relation between a gear ratio intended by the ratio change instruction and an actual gear ratio actually established by the transmission while the transmission is not under a ratio change.

Description

technical field [0001] The present invention relates to a control for detecting the occurrence of an interlock in a stepped automatic transmission. Background technique [0002] In an automatic transmission, a plurality of friction elements are selectively engaged or released, and by combining the engaged and released states of the friction elements, a predetermined shift stage is realized. [0003] However, if the valve, which is an actuator that drives the friction elements in the coupling direction, is stuck, or if the friction elements are always coupled and stick, the friction elements that are not coupled at the same time are coupled. As a result, a so-called interlock occurs, causing rapid deceleration unintentional by the driver. [0004] Therefore, Patent Document 1 discloses a technique in which a hydraulic pressure sensor is provided in an operating hydraulic circuit of each friction element, and when hydraulic pressure is supplied without outputting a signal to ...

AI Technical Summary

Problems solved by technology

In addition, affected by the hydraulic vibration, the hydraulic switch conducts the action, which leads to frequent misjudgment of the occurrence of the interlock

[0007] On the other hand, when the interlock is detected from the variation of the vehicle's front-rear acceleration, for example, it is considered to detect the front-rear acceleration from the variation of the output shaft rotational speed per unit time. state, the output shaft speed drops sharply, therefore, it is judged on the outside that a sudden deceleration has occurred and it is mistakenly judged as interlocking

In addition, even if the sensor for detecting the front and rear acceleration is not used, when the vehicle goes uphill suddenly (especially a tractor) or enters a ditch during driving, the driving resistance of the vehicle increases sharply, resulting in sudden deceleration. interlock

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