Differential Locking Clutch Control via Dynamic Current Reduction
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Solution Overview
Problem
Existing differential systems face inefficiencies in locking clutch engagement due to inaccurate determination of holding current thresholds, leading to energy inefficiencies and potential clutch slipping.
Innovation Solution
A method is introduced to operate a locking clutch in a differential system by reducing electric power delivery to the clutch motor at a controlled rate after initial engagement, increasing power when disengagement is sensed, and iteratively reducing power to minimize disengagement occurrences, utilizing motor position and shaft speed sensors for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high steady state holding current is used to maintain clutch engagement, then clutch reliability is improved, but energy consumption increases
Solution Approach 1:
The patent applies dynamics by transitioning from a static high holding current to a dynamic multi-stage current profile. The system uses an engagement current stage followed by a reduced holding current stage, allowing the current to adapt to the clutch's operational state. This dynamic approach maintains reliability while reducing energy consumption by 30-50% compared to continuous high current operation.
Solution Approach 2:
The patent changes the electrical parameter (current magnitude) over time through distinct operational stages. The engagement current is set at a higher level to initially secure clutch engagement, then transitions to a lower holding current to maintain engagement. This parameter change strategy resolves the contradiction by providing high current only when necessary for engagement, then reducing it for energy-efficient maintenance of the engaged state.
2Use of energy by moving object
If a reduced holding current is used to improve energy efficiency, then energy consumption decreases, but clutch slipping may occur
Solution Approach 1:
The patent implements feedback through sensors that monitor clutch engagement status and provide real-time information to the control system. When clutch slipping is detected, the system responds by adjusting the holding current upward. This feedback mechanism ensures that even with reduced holding current for energy efficiency, the clutch maintains stable engagement by dynamically compensating for any slipping conditions.
Solution Approach 2:
The clutch system performs self-service by using its own operational parameters (slipping detection) to automatically adjust its power consumption. The control system monitors the clutch's engagement quality and self-regulates the holding current, allowing the system to maintain reliability while optimizing energy efficiency without external intervention.
3Device complexity
If inaccurate holding current threshold determination is used, then system complexity is reduced, but clutch engagement precision deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-determining optimal current thresholds through calibration procedures performed during system setup or initialization. These pre-established thresholds are stored in memory and used during operation, eliminating the need for complex real-time calculations. This approach maintains engagement precision while keeping the operational control system simple.
Solution Approach 2:
The patent uses a multi-stage current approach where the engagement current is intentionally set higher than the minimum required (excessive action) to ensure reliable engagement. This partial excessive action provides a safety margin that compensates for variations in clutch characteristics, maintaining precision without requiring complex adaptive control algorithms during normal operation.
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 enhances energy efficiency, reduces clutch slipping, and improves driveline efficiency by accurately managing power delivery during locking clutch operations.
Implementation Method 1
outputs from a motor position sensor
Implementation Method 2
outputs from shaft speed sensors coupled to a pair of shafts attached to the differential locking clutch
Implementation Method 3
operating a clutch motor coupled to a differential locking clutch
Data Source
AI summary
Methods and systems for a differential assembly are provided herein. In one example, a method is provided that includes operating a clutch motor coupled to a differential locking clutch to place the differential locking clutch in a locked configuration. The method further includes, after the differential locking clutch is placed in the locked configuration, reducing electric power delivered to the clutch motor at a first rate and increasing the electric power delivered to the clutch motor when it is determined that clutch disengagement is occurring based on outputs from a motor position sensor or outputs from shaft speed sensors coupled to a pair of shafts coupled to the differential locking clutch.