Range Switchover Apparatus Encoder Reference Position Learning
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Solution Overview
Problem
Existing range switchover apparatuses in motor-driven systems face challenges in accurately learning the reference position due to play in the power transfer path, affecting the precision of encoder count values for motor control.
Innovation Solution
A range switchover apparatus with a detent mechanism and a control unit that includes a resting check, range check, and reference position check parts, allowing for accurate calculation of the encoder count value at a reference position by determining when the range switchover mechanism is at rest and matching the encoder count value with the actual rotation position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a position sensor is used to learn the reference position by utilizing play in the power transfer path, then the system is simpler to implement, but the reference position cannot be learned accurately
Solution Approach 1:
The patent introduces a detent mechanism as an intermediary component between the motor and the position sensor. This mechanism includes engagement members that fit into range holding recesses at specific positions, providing physical reference points that allow accurate determination of the reference position despite the presence of play in the power transfer path. The detent mechanism acts as a mediator that translates the motor's rotation into discrete, accurately knowable position states.
2Measurement precision
If an encoder is used to output pulse signals in synchronism with motor rotation, then the measurement precision is improved, but the reference position still cannot be learned accurately due to play in the power transfer path
Solution Approach 1:
The patent replaces the purely mechanical reference position learning method (based on position sensor detection) with a hybrid approach that uses the detent mechanism's mechanical engagement to establish reference points, then uses the encoder's electrical pulse signals to precisely count and record the reference position. The encoder count value at the moment of detent engagement is stored as the reference, combining mechanical reliability with electrical precision.
3Manufacturing precision
If the range switchover mechanism is held at each range position by a detent mechanism, then the positioning accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent segments the continuous rotation of the motor into discrete, controlled positions using the detent mechanism. The range holding recesses are positioned at specific intervals corresponding to different shift ranges (P, R, N, D), and the engagement members selectively engage with these recesses to hold the mechanism at each desired position. This segmentation allows accurate positioning without requiring complex continuous control systems.
Data Source
AI summary
In a range switchover control apparatus, a microcomputer checks, under a state that driving force of a motor is released, whether a range switchover mechanism is at rest and whether the range switchover mechanism is at rest in a bottom position, that is, whether an engagement member is fitted deep into a bottom of a range holding recess. If the range switchover mechanism is at rest in the bottom position, an encoder count value at a reference position (bottom position of a P-range) is calculated based on a present range and an encoder count value. By using the present range and the calculated encoder count value, an encoder count value of the bottom position of the present range can be determined. Based on this encoder count value, the encoder count value at the reference position can be calculated.