Shift Range Switching Apparatus Backlash Correction
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Solution Overview
Problem
The existing electric actuator-based shift range switching apparatus for automatic transmissions faces accuracy issues due to deviations between the rotor angle and actual shift range position, caused by manufacturing errors and mechanical backlash, leading to inconsistent control and potential oscillations in the detent mechanism.
Innovation Solution
The apparatus incorporates a recognized position correcting mechanism that adjusts the electric motor's rotation angle based on variations in rotor and output shaft angles, utilizing mechanical backlash to self-correct and align the recognized position with the actual shift range position, ensuring precise control and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an electric actuator with reduction gear is used to switch shift range, then the shift range can be controlled electrically without mechanical connection to the shift range set means, but manufacturing errors and mechanical backlash cause deviation between the rotor angle and actual shift range position
Solution Approach 1:
The patent employs feedback control by detecting the actual shift range position and comparing it with the target position, then adjusting the motor rotation angle accordingly. The feedback control unit modifies the commanded rotation angle based on the detected position difference, ensuring accurate positioning despite manufacturing errors and mechanical backlash in the reduction gear.
Solution Approach 2:
The patent changes the control parameter from directly controlling motor rotation angle to controlling the difference between target and actual positions. By calculating the position difference and adjusting the motor rotation based on this difference, the system compensates for mechanical errors and achieves precise shift range positioning.
2Device complexity
If the rotor angle is directly used as the recognized shift range position, then the control system is simple, but the recognized position deviates from the actual shift range position due to mechanical errors
Solution Approach 1:
Instead of directly using the rotor angle as the recognized position, the system implements feedback by detecting the actual shift range position and using this information to correct the recognized position. The feedback control unit calculates the difference between target and actual positions and adjusts the motor control accordingly, maintaining simplicity while improving accuracy.
Solution Approach 2:
The patent replaces direct mechanical coupling between the shift range set means and the switching mechanism with an electrical control system. The motor controller electrically adjusts the motor rotation angle based on detected position differences, substituting mechanical precision requirements with electrical control and feedback mechanisms.
3Ease of manufacture
If mechanical portions are used in the electric actuator and shift range switching mechanism, then the structure is practical and manufacturable, but manufacturing errors cause inconsistency between rotor angle and actual shift range position
Solution Approach 1:
The patent accepts the inevitability of manufacturing errors in mechanical components and compensates for them through feedback control. The system detects the actual shift range position and uses this feedback to adjust the motor rotation angle, eliminating the need for extremely high manufacturing precision while maintaining practical manufacturability.
Solution Approach 2:
The system performs self-correction by automatically detecting position deviations and adjusting the motor rotation accordingly. The feedback control unit continuously monitors the shift range position and makes real-time adjustments, allowing the system to self-compensate for manufacturing errors without requiring external calibration or adjustment.
Data Source
AI summary
By utilizing a mechanical backlash generated between an electric actuator and a shift range switching mechanism, a specific region is obtained, in which a variation in the output shaft angle is relatively small with respect to a variation in rotor angle. In this specific range, an actual shift range position is calculated, whereby the rotor angle that the motor controller recognizes is corrected so as to relate the actual shift range position. A deviation between the rotor angle and the actual shift range is corrected, so that the shift range switching is precisely performed.