Four-Wheel-Drive Torque Control via Rotational Speed Feedback
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Solution Overview
Problem
Four-wheel-drive vehicles face challenges in accurately controlling transmission torque due to changes in electronic control couplings over time, especially when lifted or on a chassis dynamometer, leading to inaccuracies in torque control during vehicle usage.
Innovation Solution
A control device with a storage portion for the relationship between drive current and transmission torque, a control portion to adjust the drive current, and a learning portion that corrects this relationship by applying braking torque using an electromagnetic actuator, ensuring synchronization of rotational speeds between input and output sides to achieve precise torque control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a learning correction is performed for the relationship between drive current and transmission torque while the vehicle is lifted or on a chassis dynamometer, then the relationship can be calibrated, but the transmission torque cannot be accurately controlled during actual vehicle operation due to component variations and aging
Solution Approach 1:
The system performs feedback learning during actual vehicle operation by detecting rotational speeds of both input and output rotating members. The learning control unit compares these speeds to determine when transmission torque balances braking torque, then uses this feedback to correct the drive current-transmission torque relationship stored in memory, ensuring accurate torque control adapts to component variations and aging during real usage conditions
Solution Approach 2:
The system performs self-calibration during normal vehicle operation without requiring external equipment like chassis dynamometers or vehicle lifting. The learning control unit automatically detects torque balance conditions through rotational speed comparison and autonomously corrects the stored relationship, allowing the system to self-adjust to component variations and aging while the vehicle is in service
2Adaptability or versatility
If the electronic control coupling is used to control transmission torque, then torque can be adjusted, but the control accuracy deteriorates over time due to component variations and aging
Solution Approach 1:
The system performs preliminary calibration by storing the drive current-transmission torque relationship in memory before actual operation. During vehicle usage, the learning control unit continuously refines this pre-stored relationship through feedback learning, correcting deviations caused by component variations and aging, thereby maintaining accurate torque control capability over time
Solution Approach 2:
The system changes the parameters of the drive current-transmission torque relationship through learning correction. The learning control unit updates the stored relationship values in memory based on actual operational feedback, adapting the torque control parameters to account for component variations and aging, thus maintaining precision despite parameter drift over time
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
The solution enables highly accurate control of transmission torque with respect to changes in electronic control couplings over time, allowing for precise torque management during vehicle operation by learning and adjusting the drive current and braking torque based on rotational speed synchronization.
Implementation Method 1
a connecting/disconnecting mechanism connecting/disconnecting the input-side rotating member of the electronic control coupling to transmit/interrupt an input of power through an operation of an electromagnetic actuator applying a braking torque to the input-side rotating member of the electronic control coupling
Data Source
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AI summary
A control device of a four-wheel-drive vehicle having an electronic control coupling (92L, 92R) changing a transmission torque, and a connecting/disconnecting mechanism (32) connecting/disconnecting an input to the input-side rotating member of the coupling, the control device (78) comprises: a storage portion (180a, 182a) storing a relationship between the drive current to the coupling and the transmission torque of the coupling; a control portion (180, 182) controlling the drive current based on the relationship; and a learning portion (180b, 182b) performing correction for the relationship through learning by applying a braking torque to the input-side rotating member by an electromagnetic actuator (128). The learning portion performs the correction for the relationship by using the drive current supplied to the coupling and the braking torque at the time of determination that the transmission torque is balanced with the braking torque based on rotational speeds of the input-side rotating member and the output-side rotating member while the rotational speed of the input-side rotating member is increased.