4WD Multi-Plate Clutch Pre-Charge Control for Fast Transition
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Solution Overview
Problem
Current 4WD vehicle control systems experience delays in transitioning from 2WD to 4WD due to the time required to fill the clutch pack of the multi-plate clutch, affecting responsiveness and fuel efficiency.
Innovation Solution
An electronic control unit is used to initiate pre-charge control of the multi-plate clutch before the transition is determined, synchronizing the rotation speeds of the clutch members and adjusting engagement force based on hydraulic oil temperature and driving conditions to maintain the propeller shaft in a state ready for immediate rotation speed increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engagement control for the multi-plate clutch is initiated when wheel slip is detected, then the clutch engagement is controlled to synchronize rotation speeds, but the time required to fill the clutch pack with hydraulic oil delays the initiation of propeller shaft rotation speed increase
Solution Approach 1:
The control device initiates pre-charge control of the multi-plate clutch before the transition from 2WD to 4WD is determined. By activating the pre-charge pump in advance to fill the clutch pack with hydraulic oil, the system prepares the clutch for immediate engagement, eliminating the delay that would otherwise occur when waiting for hydraulic oil to fill the clutch pack after engagement control is initiated.
Solution Approach 2:
The system counteracts the potential delay caused by hydraulic oil filling time by performing the pre-charge action in advance. The pre-charge pump is activated beforehand to ensure the clutch pack is already filled with hydraulic oil, preventing the time loss that would occur if filling happened after the engagement decision was made.
2Speed
If the engagement force of the clutch is controlled to maintain the propeller shaft in a state prior to rotation speed increase, then responsiveness is improved, but energy consumption increases due to continuous engagement force application
Solution Approach 1:
The control device dynamically adjusts the engagement force of the multi-plate clutch based on the vehicle's operating conditions and the stage of transition. By varying the engagement force rather than maintaining a constant high force, the system achieves the necessary responsiveness for 4WD transition while reducing unnecessary energy consumption during intermediate states.
Solution Approach 2:
The system changes the engagement force parameter of the clutch according to the transition progress and hydraulic oil temperature. By adjusting this parameter dynamically, the control device optimizes the balance between achieving fast transition responsiveness and minimizing energy consumption, particularly by reducing engagement force when high force is not needed for the current transition stage.
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 reduces the time to initiate propeller shaft rotation speed increase, enhancing responsiveness and reducing energy consumption by optimizing engagement force, thus improving the transition to 4WD mode while maintaining fuel efficiency.
Implementation Method 1
The clutch has a first rotating member and a second rotating member configured to rotate relative to the first rotating member. The clutch is configured to control an engagement force while synchronizing the rotation speed of the first rotating member and the rotation speed of the second rotating member.
Data Source
AI summary
Control device for a 4WD vehicle is provided. The 4WD vehicle includes a driving force source, main driving wheels, auxiliary driving wheels, a driving force transmission shaft, a first disconnection mechanism, and a second disconnection mechanism. The first disconnection mechanism and the second disconnection mechanism are engaged during 4WD traveling. One of the first disconnection mechanism and the second disconnection mechanism is a clutch. The control device includes an electronic control unit. The electronic control unit is configured to execute engagement control for controlling the engagement force of the clutch so that the driving force transmission shaft is maintained in a state prior to the initiation of a continuous increase in the rotation speed of the driving force transmission shaft.