Lock-up clutch slip engagement timing control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle start control systems face challenges in maintaining driving performance under heavy loads, as slip control for the lock-up clutch can lead to excessive torque capacity, reduced engine speed, and decreased fuel efficiency, while starting in a disengaged clutch state can result in rapid engine speed increase and poor fuel efficiency.
Innovation Solution
A device and method that control the start of a vehicle by detecting a start request and waiting for a predetermined time period and output rotation speed increase before engaging the lock-up clutch in slip engagement, allowing torque transmission only when the turbine rotation speed reaches a predetermined level, thereby stabilizing torque transmission timing regardless of vehicle load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If slip control for the lock-up clutch is performed whenever the vehicle starts, then torque transmission efficiency is improved, but the lock-up clutch is subjected to excessive load when the vehicle is subjected to a large load
Solution Approach 1:
The control device waits for a predetermined time period to elapse since detection of the start request before placing the lock-up clutch in slip engagement. This preliminary waiting action ensures that the turbine rotation speed has increased to a predetermined rotation speed or higher, preventing excessive load on the lock-up clutch during high-load vehicle starts while still enabling torque transmission efficiency improvement under normal conditions
2Strength
If the lock-up clutch is disengaged to avoid excessive load, then lock-up clutch durability is protected, but engine speed rapidly increases and fuel efficiency decreases
Solution Approach 1:
The control device dynamically determines the engagement timing of the lock-up clutch based on the elapse of a predetermined time period since start request detection and the turbine rotation speed reaching a predetermined level. This dynamic control allows the lock-up clutch to be engaged in slip control state when appropriate, improving fuel efficiency, while avoiding engagement under high-load conditions to protect durability
3Power
If the lock-up clutch is engaged earlier to improve driving performance, then torque transmission is enhanced, but the torque capacity becomes overabundant and engine speed does not rapidly increase
Solution Approach 1:
The control device uses feedback from the turbine rotation speed detection to determine the optimal engagement timing of the lock-up clutch. By monitoring whether the turbine rotation speed has increased to a predetermined rotation speed or higher after a predetermined time period, the control device ensures that slip control is only applied when it will improve driving performance without causing overabundant torque capacity that would suppress engine speed response
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures sufficient torque transmission and improved driving performance by controlling the lock-up clutch engagement based on predetermined conditions, preventing excessive torque capacity and maintaining stable engine speed, thus enhancing fuel efficiency and reducing driver discomfort.
Implementation Method 1
a hydraulic pressure control circuit that controls torque transmitted by the lock-up clutch by controlling an engagement force of the lock-up clutch
Implementation Method 2
an output of a driving force source is output from a transmission via a torque converter including a lock-up clutch
Data Source
AI summary
A start request detection unit detects a start request for a vehicle. A hydraulic pressure control circuit controls torque transmitted by a lock-up clutch by controlling an engagement force of the lock-up clutch. A rotation speed detection unit detects an output rotation speed of a torque converter. An engagement control unit issues an instruction to the hydraulic pressure control circuit such that the lock-up clutch is placed in slip engagement and is able to transmit the torque when the following conditions are both satisfied: a predetermined time period has elapsed since detection of the start request by the start request detection unit; and the output rotation speed has increased to a predetermined rotation speed or higher.