Automatic Transmission Solenoid Current Control for Stable Shifts

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Solution Overview

Problem

As the number of gear positions in automatic transmissions increases, the total current consumption of shift solenoids rises, leading to an increased solenoid load on the transmission control unit, which can impair the disconnection diagnosis function and result in delays and deviations in oil pressure during gear shifts.

Innovation Solution

A control device with a solenoid management controller that supplies an offset current value to disengagement solenoids and reduces the current value to disengagement solenoids when the total current exceeds a predetermined value, separating high and low load scenes to manage current consumption effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the number of gear positions is increased, then the transmission ratio range is improved, but the total current consumption of shift solenoids increases

Engineering Contradiction:

Improvegear position rangeVSAvoidcurrent consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic current control by switching between first and second current values based on gear position. The control unit determines the current value for each shift solenoid according to the current and target gear positions, optimizing current consumption across different transmission ratios while maintaining adequate solenoid actuation performance.

Inventive Principle:

Principle #15Dynamics

2Reliability

If current is supplied to all shift solenoids for diagnosis, then the disconnection diagnosis function is improved, but the solenoid load on transmission control unit increases

Engineering Contradiction:

Improvedisconnection diagnosis functionVSAvoidsolenoid load

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent applies different current values to different shift solenoids based on their specific positions and functions. By supplying the first current value to engagement solenoids and the second current value to disengagement solenoids, the system achieves localized optimization that maintains diagnostic capability where needed while reducing overall power consumption.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The control unit changes the current parameter supplied to shift solenoids based on gear position and solenoid function. By dynamically adjusting between first and second current values, the system maintains adequate diagnostic current where necessary while reducing current consumption in other scenarios, thereby managing the trade-off between diagnosis reliability and power consumption.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11808349B2Control device and control method for automatic transmission, and non-transitory computer-readable medium

Publication Date: 2023.11.07 JATCO LTD

AI summary

The control device is configured to supply an offset current value to disengagement solenoids of disengagement-side friction engaging elements among a plurality of shift solenoids that control respective shift oil pressures applied to the plurality of friction engaging elements, and when a current gear position is a first speed position or a reverse position, decrease a current value to be supplied to at least one of the disengagement solenoids that are supplied with the offset current value to be lower than the offset current value.