Dog Clutch Actuation for Tooth Alignment in EV Gearboxes
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Solution Overview
Problem
Existing unsynchronized dog clutches in electrically powered vehicles experience tooth-on-tooth misalignment during gear shifts, leading to load shocks, increased wear, and inefficiencies due to the need for frictional synchronization, which increases manufacturing costs and energy consumption.
Innovation Solution
A method and device for actuating a dog clutch in an electric vehicle transmission that determines the relative rotational speeds and angular positions of the sliding sleeve and clutch body to prevent tooth-on-tooth misalignment by electronically controlling the electric drive motor and actuator, ensuring precise alignment before engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If unsynchronized dog clutches are used to shift between gear ratios, then manufacturing costs are reduced and energy consumption is lowered by avoiding synchronization devices, but tooth-on-tooth misalignment occurs during engagement causing load shocks and increased wear
Solution Approach 1:
The control unit determines the angular positions of both the sliding sleeve and clutch body before engagement occurs. Based on these predetermined angular positions, the control unit calculates the optimal actuation timing to ensure that when the sliding sleeve engages the clutch body, the jaw teeth are properly aligned rather than colliding. This preliminary determination of angular positions and timing prevents tooth-on-tooth misalignment while maintaining the simplicity of unsynchronized clutches.
Solution Approach 2:
The system continuously monitors the actual angular positions of the sliding sleeve and clutch body during operation. Based on this feedback, the control unit dynamically adjusts the actuation timing and duration to ensure proper tooth alignment during engagement. This closed-loop control compensates for variations in rotational speeds and positions, preventing misalignment while maintaining the cost-effective unsynchronized clutch design.
2Device complexity
If unsynchronized dog clutches are used, then the structure is simplified and costs are reduced, but load shocks and mechanical stress increase due to tooth-on-tooth misalignment
Solution Approach 1:
The control unit determines the angular positions of both the sliding sleeve and clutch body before engagement occurs. Based on these predetermined angular positions, the control unit calculates the optimal actuation timing to ensure that when the sliding sleeve engages the clutch body, the jaw teeth are properly aligned rather than colliding. This preliminary determination of angular positions and timing prevents tooth-on-tooth misalignment while maintaining the simplicity of unsynchronized clutches.
Solution Approach 2:
The system continuously monitors the actual angular positions of the sliding sleeve and clutch body during operation. Based on this feedback, the control unit dynamically adjusts the actuation timing and duration to ensure proper tooth alignment during engagement. This closed-loop control compensates for variations in rotational speeds and positions, preventing misalignment while maintaining the cost-effective unsynchronized clutch design.
3Reliability
If frictional synchronization is implemented to prevent misalignment, then engagement reliability is improved, but manufacturing costs increase due to additional synchronization devices
Solution Approach 1:
The invention replaces the mechanical synchronization devices with an electronic control system. Instead of using frictional synchronization mechanisms to align the jaw teeth, the control unit electronically determines the angular positions of the sliding sleeve and clutch body and calculates the optimal actuation timing. This substitution of mechanical synchronization with electronic control achieves reliable tooth alignment while avoiding the additional manufacturing costs and structural complexity of synchronization devices.
4Manufacturing precision
If precise angular position control is implemented, then tooth-on-tooth misalignment is avoided, but control complexity and measurement requirements increase
Solution Approach 1:
The control unit performs multiple functions: it determines angular positions, calculates optimal actuation timing, and controls the actuator. By consolidating these functions into a single control unit rather than requiring separate specialized components for each function, the system achieves precise alignment control without proportionally increasing overall control complexity. The control unit leverages existing sensors and actuators in the transmission system, making the precision control achievable with minimal additional complexity.
Data Source
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AI summary
The invention relates to a method and a device for actuating a jaw clutch (6) of a transmission (2) of an electrically powered vehicle (1), in which at least relative rotational speeds and/or angular positions of a sliding sleeve (7) and a clutch body (12) are determined relative to each other, and in which at least one electric drive motor (5) of the vehicle (1) and/or an electric actuator (16) of a switching element (15) are electronically controlled as a function of the determined rotational speeds and/or angular positions in order to avoid a possible tooth-on-tooth position when switching a positive locking connection between the clutch body (12) and the sliding sleeve (7).In the case of a predicted tooth-to-tooth alignment, control measures are carried out on the at least one electric drive motor (5) and/or on the electric actuator (16) of the switching element (15), which change the relative rotational angle position of the sliding sleeve (7) and the coupling body (12) to each other and/or the movement duration of the sliding sleeve (7) in such a way that, upon reaching an engagement position, a delay-free positive engagement of associated jaw teeth (10, 13) takes place.