Shift Range Switching Device Cogging Torque Compensation
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Solution Overview
Problem
Conventional shift range switching devices face challenges in accurately switching shift ranges when using motors that generate cogging torque, as the engaging portion may not be held at the center of the valley portion due to the influence of cogging torque, leading to improper hydraulic pressure control.
Innovation Solution
A shift range switching device configuration that includes a motor, an output shaft, a valley forming member, and an engaging member, where the motor control unit determines the motor target position to shift the engaging member before the center of the target valley portion, and performs reverse control to ensure the engaging member is fitted to the center using the resilience of a biasing member, even when a motor with cogging torque is used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a motor that generates cogging torque is employed, then the motor can be used instead of an SR motor, but the engaging portion cannot be held at the center of the valley portion due to cogging torque influence
Solution Approach 1:
The motor control unit performs preliminary positioning by determining a motor target position that accounts for cogging torque effects, then executes a reverse control operation after the motor stops to ensure the engaging member reaches the precise center of the target valley portion. This two-stage control approach (initial positioning followed by correction) resolves the positioning inaccuracy caused by cogging torque.
Solution Approach 2:
The system uses feedback control where the motor control unit monitors the motor stopping position and executes reverse control based on the determined motor target position. This closed-loop control mechanism compensates for cogging torque effects and ensures the engaging member is accurately positioned at the center of the valley portion, maintaining positioning precision despite using motors with cogging torque.
2Reliability
If the engaging portion is not held at the center of the valley portion, then shift range switching may be improper, but increasing control complexity to achieve precise positioning is not desirable
Solution Approach 1:
The motor control unit changes the control parameter by determining a specific motor target position that compensates for cogging torque effects. By adjusting the target position parameter and executing reverse control, the system achieves reliable engaging member positioning without requiring complex mechanical structures or additional hardware, thus maintaining control system simplicity while improving switching reliability.
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
This configuration allows for appropriate shift range switching and reliable hydraulic pressure control by ensuring the engaging member is correctly positioned at the center of the target valley portion, even with motors that generate cogging torque, thereby maintaining proper shift range manipulation.
Implementation Method 1
the engaging member is biased with a biasing member in a direction to be fitted to the valley portion
Data Source
AI summary
An output shaft receives transmission of a driving force of a motor. A valley forming member has valley portions correspondingly to shift ranges and rotates integrally with the output shaft. An engaging member is biased with a biasing member in a direction to be fitted to a valley portion and is configured to be fitted to a target valley portion, which is a valley portion corresponding to a target shift range. The motor control unit performs a control to drive the motor. The motor shaft, which is a rotary shaft of the motor, and the output shaft have a play therebetween. The motor control unit determines a motor target position to locate the engaging member at a position shifted by a predetermined amount before the center of the target valley portion in the driving direction.