CVT Shift Line Control for Automatic Braking Energy Management

Solution Overview

Problem

During automatic braking in vehicles with continuously variable transmissions, rapid deceleration leads to insufficient downshifting due to limited maximum instantaneous energy, resulting in inadequate driving force for restarting or reacceleration, causing discomfort for the driver.

Innovation Solution

A control device that changes the shift line of the continuously variable transmission to the high rotation side during automatic braking, allowing partial downshift before rapid deceleration, and reduces downshift amount and speed during deceleration to suppress maximum energy requirements, ensuring sufficient downshifting and driving force upon restarting or reacceleration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If automatic brake is executed during sailing stop, then brake system energy is prioritized for safety, but transmission instantaneous energy is limited causing insufficient downshift

Engineering Contradiction:

Improvebrake system reliabilityVSAvoidtransmission downshift performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The control device performs preliminary downshift action before automatic brake execution by changing the shift line to the high rotation side when deceleration is detected. This allows the transmission to be partially downshifted in advance, reducing the downshift amount required during brake execution and thereby limiting instantaneous energy consumption during the critical braking period while maintaining brake system priority.

Inventive Principle:

Principle #10Preliminary action

2Speed

If transmission downshifts at high shift speed during rapid deceleration, then downshift is performed quickly, but instantaneous energy requirement exceeds maximum available energy

Engineering Contradiction:

Improveshift speedVSAvoidinstantaneous energy consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The control device performs preliminary downshift action before automatic brake execution by changing the shift line to the high rotation side when deceleration is detected. This allows the transmission to be partially downshifted in advance, reducing the downshift amount required during brake execution and thereby limiting instantaneous energy consumption during the critical braking period while maintaining brake system priority.

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If downshift amount during rapid deceleration is reduced, then instantaneous energy is suppressed, but downshift may be insufficient for restarting driving force

Engineering Contradiction:

Improveinstantaneous energy consumptionVSAvoiddriving force

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The control device performs preliminary downshift action before automatic brake execution by changing the shift line to the high rotation side when deceleration is detected. This allows the transmission to be partially downshifted in advance, reducing the downshift amount required during brake execution and thereby limiting instantaneous energy consumption during the critical braking period while maintaining brake system priority.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device dynamically adjusts the shift line based on driving conditions. When deceleration is detected, the shift line is changed to the high rotation side to enable preliminary downshift. After automatic brake release, the shift line returns to the normal position, allowing the transmission to achieve sufficient downshift for restarting driving force while maintaining low instantaneous energy consumption during braking.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10962111B2Control device and control method for vehicle including continuously variable transmission

Publication Date: 2021.03.30 JATCO LTD

AI summary

A controller changes a shift line of the continuously variable transmission to a high rotation side when execution of automatic brake is detected during sailing stop which stops the engine while driving the vehicle.