Vehicle Transmission Clutch Touch Point Learning
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Solution Overview
Problem
Conventional methods face challenges in accurately learning the touch point of a clutch in a transmission apparatus with a three-stage capacity clutch, especially when the clutch lift characteristic is steep, leading to difficulties in determining the touch point, especially on the shift-down side.
Innovation Solution
A transmission apparatus configuration that includes a shift spindle with a clutch actuator and a shift actuator, a drum angle sensor, and a controller that rotates the shift spindle to learn the touch point by storing the driving duty at a drum angle threshold and detecting the torque required for partial clutch engagement, using ramp response to reflect torque variations accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the clutch lift characteristic relative to the rotary angle of the shift spindle is set to rise early and increase at a steep gradient on the shift-down side, then the clutch engagement response is improved, but it becomes difficult to learn the touch point with high accuracy
Solution Approach 1:
The controller rotates the shift spindle to the shift-up side before learning the touch point on the shift-down side. This preliminary action positions the clutch in a state where the drum angle sensor can accurately detect the drum angle threshold, establishing a reference point (standard duty) that enables subsequent accurate touch point detection even with steep clutch lift characteristics
Solution Approach 2:
The system uses feedback from the drum angle sensor to detect when the drum angle reaches the threshold during shift-up, stores this as standard duty, then uses this reference to compare against duty values during shift-down to learn the touch point. The feedback loop enables accurate touch point determination despite steep clutch lift gradients by referencing the known drum angle threshold position
2Ease of operation
If learning of the touch point is performed at a neutral position in a transmission apparatus with a three-stage capacity clutch, then the learning process is simplified, but the touch point cannot be learned when the clutch does not slide even upon change from fully engaged to higher intermediate clutch capacity
Solution Approach 1:
The invention extracts the touch point learning process from the neutral position context and relocates it to occur during shift-down operations. By separating the learning timing from neutral position requirements, the system can reliably learn the touch point regardless of whether the clutch slides during intermediate capacity transitions at neutral
Solution Approach 2:
The system dynamically determines the appropriate learning condition based on operational state. Instead of requiring static neutral position, the learning occurs dynamically during shift-down when the clutch is actively engaging, using the drum angle sensor and duty comparison to identify the touch point at the moment of partial clutch engagement
Data Source
AI summary
A transmission apparatus for a vehicle includes a shift spindle having a clutch actuator, and also includes a shift actuator adapted to operate a shift drum. The apparatus also includes a motor for rotating the shift spindle, and a controller for controlling the motor. In use, the clutch actuator is rotated prior to the shift actuator when the shift spindle is rotated to a shift-down side. The controller rotates the shift spindle to a shift-up side and stores, as a standard duty, a driving duty of the motor at the time when a rotary angle of the shift drum reaches a drum angle threshold. Then, the controller rotates the shift spindle to a shift-down side, and learns a rotary angle of the shift spindle at the time when the standard duty is generated, as a touch point at which the clutch is initially partially engaged.