Dog Clutch Phase Identification for Low-Wear Drivetrain Shifting
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Solution Overview
Problem
Current vehicle drivetrain systems with dog clutches face challenges in reducing mechanical noise and wear during gear engagement, and the use of synchronizers is costly due to high manufacturing precision requirements.
Innovation Solution
A method and drivetrain system with a dog clutch that operates in two modes: an initial phase shift identifying mode and a normal operating mode, using a first electrical propulsion motor and a clutch actuator to perform clutch engagement movements at different relative angles, registering feedback signals to identify the initial phase shift, and then using this information for interference-free engagement, allowing for cost-efficient manufacturing and reduced noise and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If synchronizers are used during gear shifting to reduce mechanical noise and wear, then noise and wear are reduced, but manufacturing cost increases due to high precision requirements
Solution Approach 1:
The patent removes the synchronizer component from the dog clutch system entirely. Instead of using a synchronizer to equalize rotational speeds before engagement, the invention uses a control system that detects the relative angular positions of the clutch portions and timing mechanisms to enable direct engagement without mechanical speed synchronization, thereby eliminating the need for expensive precision-manufactured synchronizers.
Solution Approach 2:
The patent replaces the mechanical synchronizer system with an electronic control system that uses sensors to detect angular positions and a control unit to timing the engagement. This substitution of mechanical speed-synchronization components with electronic detection and timing control achieves the same noise and wear reduction function without requiring high-precision mechanical synchronizing components.
2Reliability
If dog clutch teeth geometry is modified to improve gear engagement, then engagement performance improves, but manufacturing complexity and cost increase
Solution Approach 1:
The control system performs preliminary detection of the relative angular positions of the first and second clutch portions using sensors before engagement occurs. Based on this detected position information, the system pre-calculates and executes the optimal timing for actuating the dog clutch, ensuring that engagement occurs at the correct moment when teeth are properly aligned, thereby improving engagement reliability without modifying tooth geometry.
Solution Approach 2:
The patent changes the control parameter from mechanical tooth geometry design to electronic timing control. Instead of modifying the physical shape or orientation of clutch teeth to improve engagement, the system uses variable timing of the actuation based on detected angular positions, allowing optimal engagement performance with standard, simple-to-manufacture tooth geometries.
3Measurement precision
If multiple clutch engagement movements are performed at different relative angles to identify initial phase shift, then engagement accuracy improves, but time consumption increases
Solution Approach 1:
The system performs self-calibration by automatically executing multiple clutch engagement movements at different relative angles and using the detected feedback signals to autonomously identify the initial phase shift. The control unit processes the sensor data and determines the correct timing parameters without requiring external intervention or manual adjustment, enabling the system to self-optimize its engagement parameters.
Solution Approach 2:
The patent incorporates feedback mechanisms where sensors detect signals from multiple clutch engagement movements at different relative angles. The control unit analyzes this feedback information to identify patterns and determine the initial phase shift that produces optimal engagement. This feedback-driven approach allows accurate phase shift identification through systematic testing and automatic parameter adjustment.
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3B
AI summary
A method for operating a vehicle drivetrain (4) including a dog clutch (31-33) and having at least two distinct operating modes: an initial phase shift identifying mode and a normal operating mode. The method comprises a first step of providing a dog clutch (31-33) for selective torque transmission, wherein the dog clutch (31-33) has a first clutch portion with a first set of teeth (31a-33a) and a second clutch portion with a second set of teeth (31b-33b), and wherein the first clutch portion is axially moveable for enabling shifting of the dog clutch (31-33) between an engaged state, in which the first and second clutch portions are operable to transmit torque between first and second clutch portion via the first and second set of teeth, and a disengaged state, in which the first and second clutch portions are rotatable with respect to each; a first electrical propulsion motor (2a, 2b) drivingly connected with one of the first and second clutch portions; and clutch actuator (13, 34) operably connected with the first clutch portion for shifting the dog clutch (31-33) between the engaged and disengaged states by controlling an axial position of the first clutch portion. The method further comprises a second step of setting the drive train (4) in the initial phase shift identifying mode, which includes controlling the clutch actuator (13, 34) and the first electrical propulsion motor (2a, 2b) for performing a plurality of clutch engagement movements for a set of different relative angles between the first and second clutch portions, while registering for each individual clutch engagement movement a clutch actuator feedback signal associated with the clutch actuator and indicative of either successful mutual intermeshing engagement of the first and second sets of teeth, or teeth collision of the first and second sets of teeth; and identifying, based on the registered clutch actuator feedback signal, the initial phase shift between the first and second clutch portions that corresponds to successful mutual intermeshing engagement of the first and second sets of teeth. Finally, the method includes a third step of setting the drivetrain (4) in a normal operating mode, which includes obtaining angular position data associated with the first and second clutch portions; controlling engagement of the dog clutch (31-33) while taking the obtained angular position data of first and second clutch portions and said identified initial phase shift into account for enabling interference-free engagement of the of the dog clutch.