Shift Range Control Device Rattle Compensation
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Solution Overview
Problem
Existing shift range control devices face challenges in accurately controlling motor position due to cogging torque and rattle width, leading to improper engagement of shift ranges, especially in DC brushless motors with contactless sensors.
Innovation Solution
A shift range control device that uses a magnetic type rotary encoder and a magnetic output shaft sensor with dual MR sensor units to detect the motor and output shaft positions, learning the rattle width and adjusting the motor angle to ensure precise engagement by calculating correction values based on change point values during shift range changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic type rotary encoder and magnetic output shaft sensor are used to detect motor and output shaft positions, then measurement precision is improved, but device complexity increases due to the need for dual sensor systems and learning mechanisms
Solution Approach 1:
The system implements feedback by continuously monitoring the output shaft position via the output shaft sensor and comparing it with the motor position from the rotary encoder. The learning unit processes this feedback information to calculate correction values that compensate for rattle width and cogging torque effects, thereby maintaining high measurement precision while managing system complexity through intelligent control algorithms.
Solution Approach 2:
The learning unit acts as an intermediary that processes data from both sensors and generates correction values. This intermediary component bridges the gap between the dual sensor system and the motor control, enabling the system to utilize the additional measurement capability without directly increasing control complexity through complex hardware modifications.
2Manufacturing precision
If correction values are calculated based on change point values during shift range changes to compensate for rattle width and cogging torque, then manufacturing precision is improved, but loss of time increases due to the learning process requirement
Solution Approach 1:
The learning unit performs preliminary action by calculating and storing correction values during a learning process that occurs during vehicle operation. Once these correction values are established, they are reused for subsequent shift range engagements, thereby amortizing the initial time investment across multiple operations and reducing the effective time loss per engagement.
Solution Approach 2:
The system implements self-service through the learning mechanism that automatically adjusts correction values based on actual operational data. The learning unit continuously refines the correction values using feedback from the output shaft sensor and rotary encoder, enabling the system to self-optimize without external intervention and maintain high engagement precision over time.
3Reliability
If the engagement member is engageable with the valley section corresponding to the shift range, then reliability is improved, but object-generated harmful factors worsen due to cogging torque causing improper engagement
Solution Approach 1:
The control unit applies preliminary anti-action by calculating correction values that preemptively compensate for cogging torque effects before the engagement occurs. The learning unit analyzes the relationship between motor position and output shaft position to determine correction values that counteract the anticipated cogging torque, thereby ensuring reliable engagement despite the presence of this harmful factor.
Solution Approach 2:
The system converts the harmful effect of cogging torque into a beneficial factor by using the learning unit to characterize and compensate for it. The correction values derived from learning the cogging torque pattern transform this previously harmful phenomenon into a predictable, compensatable effect that actually improves engagement reliability when properly accounted for.
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
The solution enables accurate positioning of the motor to match the target shift range, even with cogging torque, ensuring proper engagement of shift ranges and enhancing control accuracy.
Implementation Method 1
The motor rotation angle sensor outputs a motor rotation angle signal corresponding to a rotation position of the motor
Implementation Method 2
The output shaft sensor outputs an output shaft signal corresponding to a rotation position of the output shaft
Data Source
AI summary
A shift range control device includes an angle calculation unit, a target angle setting unit, a learning unit and a drive control unit. The learning unit learns a correction value to be used in calculating a motor angle target value based on a motor angle and an output shaft signal. The learning unit learns the correction value based on at least a first change point value, which is the motor angle at a timing at which the output shaft signal changes when a rotation member rotates in a first direction from a state in which an engagement member is in the center of valley section, and/or a second change point value, which is the motor angle at a timing at which the output shaft signal changes when the rotation member rotates in a second direction from a state in which the engagement member is in the center of the valley section.