Clutch Position Control via Torque Sensitivity Mapping
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Solution Overview
Problem
Existing methods for controlling clutch position in heavy trucks during low-speed operations, such as creeping, fail to consider torque sensitivity variations across different clutch positions, leading to non-linear and unstable vehicle speed control.
Innovation Solution
A target clutch position control method based on a clutch torque transmission curve, which includes a target torque calculation module, a change rate limitation module, and enhanced communication between the engine control unit and transmission control unit, allowing for dynamic adjustment of clutch torque and position based on accelerator pedal position and engine speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed clutch engagement speed limitation is used for all clutch strokes, then the control system is simple to implement, but the vehicle speed control becomes non-linear and unstable due to varying torque sensitivity at different clutch positions
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed clutch engagement speed limitation to a dynamic one that varies with clutch position. The control system divides the clutch stroke into multiple stages (0-50%, 50-70%, 70-100%) and assigns different speed limitations to each stage, allowing the limitation to adapt to the changing torque sensitivity characteristics at different positions, thereby achieving linear and stable vehicle speed control
Solution Approach 2:
The patent changes the parameter of clutch engagement speed limitation from a constant value to a variable value that depends on clutch position. By adjusting the speed limitation parameter according to the current clutch stroke stage, the system optimizes the engagement process for each phase, improving overall control stability while maintaining ease of operation through predefined stage-based parameters
2Stability of the object's composition
If a small clutch engagement speed limitation is used, then the clutch-transmitted torque is not sensitive to stroke increase in early stage, but the driver cannot sense vehicle reaction in a short period of time
Solution Approach 1:
The patent segments the clutch engagement stroke into distinct stages (0-50%, 50-70%, 70-100%) with different speed limitations. In the early stage (0-50%), a relatively larger speed limitation is applied to allow faster torque build-up and quicker driver perception, while in later stages (50-100%), smaller limitations are used to maintain stability during the sensitive torque transmission phase
Solution Approach 2:
The system dynamically adjusts the clutch engagement speed limitation based on the current stroke stage. During early engagement when torque sensitivity is low, the system permits higher engagement speeds to reduce perception time, while automatically reducing the limitation as the clutch approaches the sensitive torque transmission zone, thus balancing driver perception needs with transmission stability
3Productivity
If a large clutch engagement speed limitation is used, then the clutch-transmitted torque is extremely sensitive to stroke increase in later stage, but the system cannot provide the function of reducing clutch torque increasing speed to gain engine reaction time
Solution Approach 1:
The system dynamically reduces the clutch engagement speed limitation as the clutch stroke progresses into the sensitive later stages (50-100%). This dynamic adjustment allows the system to maintain high engagement speeds during less sensitive phases for productivity, while automatically slowing down the torque increase rate during sensitive phases to preserve engine reaction time
Solution Approach 2:
The control system preliminarily identifies the sensitive torque transmission zone (50-70% and 70-100% stages) and pre-adjusts the engagement speed limitation accordingly. By anticipating the upcoming sensitivity increase, the system proactively reduces the speed limitation before the sensitive phase fully engages, ensuring engine reaction time is preserved while maintaining overall engagement efficiency
Data Source
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AI summary
The present invention discloses a target clutch position control method based on a clutch torque transmission curve, the method comprising the following steps: a target torque calculation module calculates a driver target clutch torque according to an accelerator pedal position; an engine speed controller calculates a corresponding target engine speed according to the driver target clutch torque; a change rate limitation module calculates an allowable clutch torque change rate according to a difference between the calculated target engine speed and a current engine speed, and limits the currently calculated driver target clutch torque, wherein a target clutch torque obtained after the limitation; and a transmission control unit calculates a target clutch position according to the limited target clutch torque by means of performing interpolation on a clutch torque transmission curve. In the control method defined by the present invention, the target clutch position is estimated according to the torque required by the driver. The method takes a difference in torque transmission sensitivity of the clutch in different positions into consideration, so as to ensure that the driver feels that vehicle control is linear and stable.